JP2018119470A - Injection control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection control device for an engine that can supply fuel by port injection and inhibit emission from deteriorating due to blow-by phenomenon.SOLUTION: When intake pressure is higher than or equal to a predetermined intake pressure threshold, an injection control device executes injection adjustment control by increasing a ratio of a fuel injection amount in an intake stroke relative to a total fuel injection amount in one cycle, compared to that when intake pressure is lower than the intake pressure threshold.SELECTED DRAWING: Figure 6

Description

  The present disclosure relates to an injection control device.

  Conventionally, in an engine using port injection, it is known that a valve overlap period in which the open state of the intake valve and the open state of the exhaust valve overlap is provided to improve the scavenging efficiency of combustion gas and the volumetric efficiency of intake air. It has been. However, as the valve overlap period is set larger, there is a risk that so-called blow-through in which the intake air flowing in from the intake passage passes directly to the exhaust passage side may occur.

  Therefore, the control device described in Patent Document 1 below is used for an engine that uses both in-cylinder injection and port injection, and aims to suppress the occurrence of blow-through. As described above, in an engine capable of adjusting the valve timing, by providing a valve overlap period in which the open state of the intake valve overlaps the open state of the exhaust valve, the intake efficiency is improved and the internal EGR is increased. Adjust the amount. In particular, in an engine equipped with a supercharger in the intake / exhaust system, scavenging of exhaust gas is promoted by a high intake pressure by providing a valve overlap period in a supercharging region where the intake pressure is greater than atmospheric pressure, Volume efficiency can be improved, and engine output is increased.

  However, if the valve overlap period is set to be large, there is a risk that the air-fuel mixture flowing in from the intake passage will not burn but directly pass through the exhaust passage as described above. When the blow-through phenomenon occurs, a part of the air-fuel mixture does not burn, so that the engine output decreases and the emission deteriorates.

  In the following Patent Document 1, the fuel injection from the in-cylinder injection valve and the fuel injection from the port injection valve are adjusted according to the engine rotation speed, and the valve opening / closing timing is adjusted according to the engine rotation speed. It is supposed to suppress the phenomenon.

Japanese Patent Laying-Open No. 2015-10546

  In Patent Document 1, it is assumed that the engine to be controlled is a combination of in-cylinder injection and port injection. Therefore, it is not possible to suppress the blow-through phenomenon of the engine using only port injection. Further, even in an engine that uses both in-cylinder injection and port injection, if the blow-through phenomenon can be suppressed by adjusting the elements other than the port injection side or other in-cylinder injection, for example, in-cylinder injection is performed. It is possible to cope with cases where it cannot be performed.

  An object of the present disclosure is to provide an injection control apparatus for an engine capable of supplying fuel by port injection, and capable of suppressing deterioration of emission due to a blow-through phenomenon.

  The present disclosure is an injection control device, which is capable of supplying fuel by port injection, and based on intake pressure of an engine provided with a supercharger, an amount of fuel injection from a fuel injection valve to an intake port The necessity determination unit (101) for determining whether or not the injection adjustment control for adjusting the timing is necessary, and the injection adjustment unit (102, 103, 102) that executes the injection adjustment control based on the determination result of the necessity determination unit. 104), and when the intake pressure is equal to or higher than a predetermined threshold intake pressure, the injection adjustment unit performs the entire fuel injection in one cycle as compared with the case where the intake pressure is less than the threshold intake pressure. The injection adjustment control is executed by increasing the ratio of the fuel injection amount during the intake stroke to the amount.

  When the intake pressure is low, the blow-through phenomenon hardly occurs, and when the intake pressure is high, the blow-through phenomenon easily occurs. Therefore, in the present disclosure, the injection adjustment control is executed when the intake pressure becomes equal to or higher than the threshold intake pressure. As the injection adjustment control, by increasing the ratio of the fuel injection amount during the intake stroke to the total fuel injection amount during one cycle, the fuel injection amount during the valve overlap period is reduced as much as possible, and the air-fuel mixture flows out as it is. Occurrence of blow-through phenomenon is suppressed.

  According to the present disclosure, it is possible to provide an injection control device for an engine capable of supplying fuel by port injection and capable of suppressing deterioration of emissions due to a blow-through phenomenon.

FIG. 1 is a diagram for explaining a configuration of an ECU as an embodiment and an engine as a control target thereof. FIG. 2 is a diagram for explaining a part of the functional configuration of the ECU. FIG. 3 is a flowchart for explaining processing in the ECU. FIG. 4 is a flowchart for explaining an example of the injection correction process in FIG. FIG. 5 is a flowchart for explaining an example of the injection correction process in FIG. FIG. 6 is a diagram for explaining adjustment of fuel injection timing in the processing of the ECU. FIG. 7 is a diagram for explaining an example of injection end timing adjustment. FIG. 8 is a diagram for explaining an example of adjusting the injection end timing.

  Hereinafter, the present embodiment 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.

  As shown in FIG. 1, an ECU (Electronic Control Unit) 10 controls fuel injection, valve timing, ignition timing, and intake pressure of the engine 20. The engine 20 is provided with an intake passage 40 and an exhaust passage 50.

  A supercharger 30 is provided across the intake passage 40 and the exhaust passage 50. The supercharger 30 includes a turbine 301, a compressor 302, and a waste gate valve 303. The turbine 301 is provided in the exhaust passage 50. The compressor 302 is provided in the intake passage 40.

  The intake passage 40 has an intake port 40a. The intake port 40 a is connected to a combustion chamber formed by the piston 201 of the engine 20. The piston 201 is provided so as to freely slide in the cylinder. The reciprocating motion of the piston 201 is converted into the rotational motion of the crankshaft via the connecting rod.

  An intake valve 203 is provided at an opening connected to the combustion chamber of the intake port 40a. A fuel injection valve 205 is provided in the intake port 40a. In order to supply fuel to the fuel injection valve 205, a fuel pump 60 and a fuel pump control device 61 are provided. The fuel pump control device 61 drives the fuel pump 60 based on a control signal from the ECU 10. A throttle 208 is provided in the intake passage 40 upstream of the intake port 40a.

  The exhaust passage 50 has an exhaust port 50a. The exhaust port 50 a is connected to a combustion chamber formed by the piston 201 of the engine 20. An exhaust valve 204 is provided at the opening connected to the combustion chamber of the exhaust port 50a.

  A spark plug 202 is provided to ignite the air-fuel mixture that is compressed as the piston 201 rises. An intake side valve mechanism 206 is provided to adjust the operation timing of the intake valve 203 to the retard side or the advance side. An exhaust side valve mechanism 207 is provided to adjust the operation timing of the exhaust valve 204 to the retard side or the advance side. The intake side valve mechanism 206 and the exhaust side valve mechanism 207 may be configured to vary the valve lift amount and the operating angle of the intake valve 203 and the exhaust valve 204 instead of the valve timing.

An air flow meter 401 and an intake pressure sensor 403 are provided in the intake passage 40. In the exhaust passage 50, an A / F sensor 402 and an O ₂ sensor 407 are provided. The engine 20 is provided with a water temperature sensor 404, oil temperature sensors 405 and 408, and a crank angle sensor 406.

  The output signal of each sensor is input to the ECU 10. An accelerator opening signal output from the throttle 208 is also input to the ECU 10. The ECU 10 is configured as an LSI device in which a microprocessor, ROM, RAM and the like are integrated, and is connected to a communication line of an in-vehicle network provided in the vehicle.

  Next, some functional components of the ECU 10 will be described with reference to FIG. The functions of the ECU 10 are diverse in order to control the operation of the engine 20, and include functional components in addition to the functional components illustrated in FIG. The ECU 10 includes a necessity determination unit 101, an injection calculation unit 102, an injection control unit 103, a correction unit 104, a limit calculation unit 105, and a limit control unit 106 as functional components. .

  The necessity determination unit 101 is a part that determines whether or not injection adjustment control for adjusting the amount and timing of fuel injection from the fuel injection valve 205 to the intake port 40a is necessary based on the intake pressure of the engine 20. Adjusting the amount and timing of fuel injection refers to adjusting the amount and timing of fuel injection calculated based on the load and air-fuel ratio to suppress the blow-through phenomenon. The blow-through phenomenon is a phenomenon in which the air-fuel mixture flowing in from the intake port 40a passes directly to the exhaust port 50a.

  The necessity determination unit 101 determines that the injection adjustment control for adjusting the amount and timing of fuel injection from the fuel injection valve 205 to the intake port 40a is necessary when the intake pressure becomes equal to or higher than a predetermined threshold intake pressure.

  The necessity determination unit 101 can also determine whether or not injection adjustment control is necessary based on the temperature of the engine 20. The necessity determination unit determines that the injection adjustment control is necessary when the temperature is lower than a predetermined threshold temperature.

  The injection calculation unit 102 is a part that calculates the amount and timing of fuel injection from the fuel injection valve 205 to the intake port 40a. The injection calculation unit 102 calculates the amount and timing of fuel injection based on normal requirements such as load and air-fuel ratio. When the correction unit 104 outputs the fuel injection amount and timing correction amount, the injection calculation unit 102 reflects the correction amount and calculates the fuel injection amount and timing.

  The injection control unit 103 is a part that controls the fuel injection valve 205 based on the amount and timing of fuel injection output from the injection calculation unit 102.

  The correction unit 104 is a part that calculates the amount of fuel injection from the fuel injection valve 205 to the intake port 40a and the correction amount of timing based on the determination result of the necessity determination unit 101. If the determination result of the necessity determination unit 101 indicates that the injection adjustment control is not necessary, the correction unit 104 calculates the correction amount as zero. The injection calculation unit 102 calculates the amount and timing of fuel injection based on normal requirements such as load and air-fuel ratio based on the calculation result.

  On the other hand, if the determination result of the necessity determination unit 101 indicates that the injection adjustment control is necessary, the correction unit 104 calculates the ratio of the fuel injection amount during the intake stroke to the total fuel injection amount during one cycle. The fuel injection amount and the timing correction amount are calculated so as to increase. In the injection adjustment control, the correction unit 104 calculates the correction amount so that the fuel injection amount in the first half during the intake stroke is larger than the fuel injection amount in the second half during the intake stroke. The injection calculation unit 102 calculates the fuel injection amount and timing based on the correction amount calculated by the correction unit 104 and normal requirements such as load and air-fuel ratio.

  In the fuel injection period, the correction unit 104 makes the sum of the opening areas of the intake valve 203 and the exhaust valve 204 smaller than the threshold area during the valve overlap period in which both the intake valve 203 and the exhaust valve 204 of the engine 20 are open. Then, a correction amount for adjusting the fuel injection timing is determined. The sum of opening areas is obtained by integrating the opening area through which the air-fuel mixture and exhaust gas can pass through the intake valve 203 and the exhaust valve 204 over a predetermined period of time.

  The correction unit 104 determines the correction amount so as to increase the fuel injection amount within a predetermined time. Various means are used as means for increasing the fuel injection amount within a predetermined time. As an example, the correction unit 104 increases the fuel injection amount within a predetermined time by increasing the fuel pressure. If a plurality of fuel injection valves 205 are provided per cylinder, the correction unit 104 can increase the fuel injection amount within a predetermined time by increasing the number of drive of the fuel injection valves 205.

  The restriction calculation unit 105 is a part that executes blow-through adjustment control that restricts the intake air amount in parallel with the injection adjustment control, and is a part that calculates the control amount of the blow-through adjustment control. The limit calculation unit 105 calculates a limit amount so as to reduce a valve overlap period in which both the intake valve 203 and the exhaust valve 204 are open and to reduce the blow-through amount. The restriction calculation unit 105 calculates the restriction amount so that the operation amount is reduced so that the opening area of the intake valve 203 and / or the exhaust valve 204 is reduced, and the blow-through amount is reduced. The limit calculation unit 105 calculates a limit amount for driving the waste gate valve 303 so as to suppress the intake pressure by the supercharger 30. The limit calculation unit 105 outputs the calculated limit amount to the limit control unit 106.

  The restriction control unit 106 restricts and drives the intake side valve mechanism 206, the exhaust side valve mechanism 207, and the waste gate valve 303 of the supercharger 30 based on the restriction amount output from the restriction control unit 106, thereby adjusting the blow-through. This is the part that executes control.

  Next, specific control contents of the ECU 10 will be described with reference to FIG. In step S101, the necessity determination unit 101 determines whether the temperature of the engine 20 is less than a threshold temperature. The temperature of the engine 20 is grasped by the water temperature detected by the water temperature sensor 404.

  The necessity determination unit 101 determines whether or not the water temperature Tw is lower than the threshold water temperature Tth. An example of the threshold water temperature Tth is 60 ° C. If the water temperature Tw is lower than the threshold water temperature Tth, the process proceeds to step S102. If the water temperature Tw is not lower than the threshold water temperature Tth, the process proceeds to step S110. Note that the process of step S101 may be omitted, and the process of step S102 may be started regardless of the temperature of the engine 20.

  In step S102, the necessity determination unit 101 determines whether the intake pressure is greater than or equal to a threshold intake pressure. The intake pressure is grasped by the pressure detected by the intake pressure sensor 403. When the intake pressure sensor 403 is not provided, the intake pressure may be estimated from the operating state of the air flow meter 401 and the engine 20. The necessity determination unit 101 determines whether or not the intake pressure Pa is equal to or higher than the threshold intake pressure Pth. An example of the threshold intake pressure Pth is 130 kPa. If the intake pressure Pa is greater than or equal to the threshold intake pressure Pth, the process proceeds to step S103. If the intake pressure Pa is not equal to or higher than the threshold intake pressure Pth, the process proceeds to step S110.

  In step S <b> 110, the injection calculation unit 102 performs injection control setting without correction, and outputs a control value to the injection control unit 103. In the case of the injection control setting without correction, the fuel is injected during the exhaust stroke, which is the period during which the intake valve 203 is closed. Therefore, the fuel injection ratio in the intake stroke is 0%.

  In step S103, the injection calculation unit 102 calculates the fuel injection amount. In step S104 following step S103, the correction unit 104 sets the injection end timing.

  The injection end timing will be described with reference to FIG. In order to suppress the blow-through phenomenon, the entire period from the start to the end of fuel injection falls within the first half of the intake stroke period, and the sum of the opening areas of the intake valve 203 and the exhaust valve 204 during the valve overlap period is less than a predetermined value. It is preferable that The reason why the injection timing is preferably the intake stroke is that the ratio of the fuel injected while the intake valve 203 is closed increases as the ratio of the injection period before the intake stroke to the entire injection period increases. This is because it becomes wet and causes worsening of emissions. Further, the intake stroke is a period in which the piston 201 is descending from TDC toward BDC, so that the pressure in the combustion chamber becomes lower than the pressure in the intake port 40a and the exhaust port 50a, and there is an effect of suppressing blow-through.

  The reason why it is preferable that the injection end timing is the first half of the intake stroke is that the time from the injection to the ignition becomes shorter as the second half of the intake stroke is reached, the time for the fuel to evaporate and the time for mixing the air and the fuel become shorter. This is because it becomes sufficient and the emission deteriorates. In an operating condition where it is difficult to perform the entire injection period in the intake stroke period, it is preferable to set the injection timing so that the amount of fuel injected in the first half of the intake stroke in the entire fuel injection amount increases. The reason why the sum of the opening areas of the intake valve 203 and the exhaust valve 204 during the valve overlap period is preferably within a predetermined value is that there is a positive correlation between the blow-through amount and the sum of the opening areas. This is because the blow-through phenomenon can be suppressed.

  From this viewpoint, an “ideal injection period” as shown in FIG. 6 can be obtained. In FIG. 6, the intake stroke, the compression stroke, the combustion stroke, and the exhaust stroke are shown in time series. The intake TDC is a top dead center in the intake stroke. The intake BDC is a bottom dead center in the intake stroke. In the exhaust stroke, the exhaust valve 204 is mainly opened, and in the intake stroke, the intake valve 203 is mainly opened. However, a valve overlap period in which both the intake valve 203 and the exhaust valve 204 are opened is provided. The injection end timing is set to the retarded side in a range where the mixed state of fuel and air does not deteriorate and the emission does not increase so that the ratio of the injection amount in the first half of the intake stroke to the entire fuel injection amount increases. For example, in an engine in which the emission worsens significantly when injection is performed on the retard side from 120 ° after intake TDC, the 120 ° after intake TDC is set as the retard limit of the injection end timing, and the injection is performed within a range not exceeding the retard limit. Set the end time to the retard side. In the present embodiment, the injection end timing is set to the retard limit at which fuel can be injected during the “ideal injection period” under many operating conditions.

  In step S105 following step S104, the correction unit 104 calculates the injection start timing. The injection start timing is obtained by reflecting the time required for fuel injection in the injection end timing calculated in step S104.

  In step S106 following step S105, the correction unit 104 determines whether or not the injection can be completed. More specifically, it is determined whether or not the fuel injection period falls within the “ideal injection period” shown in FIG. If it is determined that fuel injection is possible, the process proceeds to step S108. If it is determined that fuel injection is not possible, the process proceeds to step S107.

  An example of the injection correction process in step S107 will be described with reference to FIGS. In the example illustrated in FIG. 4, the correction unit 104 performs an injection rate improvement calculation. The correction unit 104 increases the fuel pressure as an example of improving the injection rate. For example, the fuel pressure is increased from 300 kPa to 600 kPa, and the fuel injection amount within a predetermined time is increased. The fuel pressure increase control is executed by outputting a control signal for increasing the fuel pressure from the ECU 10 to the fuel pump control device 61. Moreover, the correction | amendment part 104 increases the drive number of the fuel injection valve 205, when the some fuel injection valve 205 is provided per cylinder as an example of injection rate improvement.

  In step S202 following step S201, the correction unit 104 reflects whether or not the fuel injection period falls within the “ideal injection period” shown in FIG. 6 by reflecting the improvement in the injection rate selected in step S201. If it is determined that fuel injection is possible, the injection correction process is terminated, and the process proceeds to step S108 in FIG. If it is determined that fuel injection is not possible, the process proceeds to step S204.

  In step S204, the limit calculation unit 105 executes a limit calculation for setting a limit amount for limiting the valve overlap amount. As an example, the limit amount is calculated so as to limit the valve overlap amount from 20 ° CA to less than 10 ° CA. As another example, the limit calculation may be executed so as to limit the valve lift amount or the working angle.

  In step S205 following step S204, the limit control unit 106 determines the advance amount and / or the intake side valve mechanism 206 and / or the exhaust side valve mechanism 207 based on the limit amount output from the limit control unit 106. Control is performed so as to limit the amount of retardation. When a mechanism capable of adjusting the valve lift amount or the working angle is provided, the restriction control unit 106 performs control so as to restrict them. When the process of step S205 is completed, the process proceeds to step S108 of FIG.

  Next, another example of the injection correction process will be described with reference to FIG. Steps S201 to S203 are the same as those described with reference to FIG. If it is determined in step S203 that fuel injection is not possible, the process proceeds to step S304.

  In step S304, the limit calculation unit 105 executes a limit calculation for limiting the intake pressure. As an example, in order to limit the intake pressure, a limit calculation that sets a limit amount so that the waste gate valve 303 opens at a lower back pressure is executed. As an example, the limit amount is calculated so that the waste gate valve 303 opens at less than 120 kPa.

  If the intake pressure can be limited, the limit amount may be set so as to limit the opening of the throttle 208. Note that limiting the intake pressure has the effect of shortening the injection period itself by suppressing the required injection amount in addition to the effect of directly suppressing the blow-through, and as a result, the “ideal” shown in FIG. The fuel injection period is likely to be within the “injection period”.

  In step S305 subsequent to step S304, the limit control unit 106 performs control so that the waste gate valve 303 opens with a lower back pressure based on the limit amount output from the limit control unit 106. When the opening degree of the throttle 208 is limited, control for limiting the opening degree of the throttle 208 is executed. When the process of step S305 is completed, the process proceeds to step S108 of FIG.

  Returning to FIG. 3, the description will be continued. In step S108, the injection control unit 103 performs fuel control based on the injection control setting without correction calculated by the injection calculation unit 102 or the injection control setting with correction reflecting the injection rate improvement calculated by the correction unit 104. Perform injection.

  As described above, in the present embodiment, the fuel injection valve 205 is based on the intake pressure of the engine 20 in which the ECU 10 that is the injection control device can supply fuel by port injection and the supercharger is provided. The necessity determination unit 101 for determining whether or not the injection adjustment control for adjusting the amount and timing of fuel injection to the intake port 40a is necessary, and the injection adjustment control is executed based on the determination result of the necessity determination unit 101 An injection calculation unit 102 as an injection adjustment unit, an injection control unit 103, and a correction unit 104 are provided. When the intake pressure is greater than or equal to a predetermined threshold intake pressure, the injection calculation unit 102, the injection control unit 103, and the correction unit 104 are in one cycle compared to when the intake pressure is less than the threshold intake pressure. Injection adjustment control is executed by increasing the ratio of the fuel injection amount during the intake stroke to the total fuel injection amount.

  When the intake pressure is low, the blow-through phenomenon hardly occurs, and when the intake pressure is high, the blow-through phenomenon easily occurs. Therefore, in the present embodiment, the injection adjustment control is executed when the intake pressure exceeds the threshold intake pressure. As the injection adjustment control, by increasing the ratio of the fuel injection amount during the intake stroke to the total fuel injection amount during one cycle, the fuel injection amount during the valve overlap period is reduced as much as possible, and the fuel-air mixture remains as it is in the exhaust port. Generation | occurrence | production of the blow-through phenomenon which flows into 50a is suppressed.

  In the present embodiment, the injection calculation unit 102, the injection control unit 103, and the correction unit 104 increase the fuel injection amount in the first half during the intake stroke more than the fuel injection amount in the second half during the intake stroke in the injection adjustment control. This is because if fuel injection is executed in the latter half of the intake stroke, the mixture of fuel and air tends to be insufficient, resulting in worse emission.

  Further, in the present embodiment, the injection calculation unit 102, the injection control unit 103, and the correction unit 104 include the intake valve 203 and the intake valve 203 in the valve overlap period in which both the intake valve 203 and the exhaust valve 204 of the engine 20 are open during the fuel injection period. The injection adjustment control is executed so that the sum of the opening areas of the exhaust valve 204 is smaller than the threshold area. This is in order to suppress the blow-through phenomenon while utilizing the merit of providing the valve overlap period.

  In the present embodiment, the necessity determination unit 101 determines whether or not the injection adjustment control is necessary based on the temperature of the engine 20, and the injection calculation unit 102, the injection control unit 103, and the correction unit 104 When the temperature is lower than a predetermined threshold temperature, the injection adjustment control is executed. This is because if the temperature of the engine 20 is low, the fuel is difficult to vaporize, the amount of fuel that blows into the exhaust port 50a in a liquid state increases, and the emission deterioration becomes more remarkable.

  Moreover, in this embodiment, the injection calculating part 102, the injection control part 103, and the correction | amendment part 104 perform injection adjustment control by increasing the fuel injection amount in predetermined time. Since the fuel injection period can be shortened by increasing the fuel injection amount within the predetermined time, the fuel injection can be completed in an ideal injection period in which deterioration of emissions can be suppressed.

  Moreover, in this embodiment, the injection calculating part 102, the injection control part 103, and the correction | amendment part 104 perform injection adjustment control by raising a fuel pressure. By increasing the fuel pressure, the fuel injection amount within a predetermined time can be increased.

  In the present embodiment, the engine 20 may be provided with a plurality of fuel injection valves 205 per cylinder. In this case, the injection calculation unit 102, the injection control unit 103, and the correction unit 104 are driven fuel injection valves. The injection adjustment control is executed by increasing the number 205. By increasing the number of fuel injection valves 205 to be driven, the fuel injection amount within a predetermined time can be increased.

  Further, in the present embodiment, a limit calculation unit 105 and a limit control unit 106 are provided as a limit unit that limits the intake air amount to the cylinder of the engine 20, and the limit calculation unit 105 and the limit control unit 106 are in parallel with the injection adjustment control. The blow-through adjustment control for limiting the intake air amount is executed.

  Ideally, the fuel injection timing is adjusted only by the injection adjustment control, and the blow-through phenomenon can be suppressed so as not to deteriorate the emission. However, when the engine speed is high or when the required fuel injection amount is large, it may be assumed that the injection adjustment control alone cannot cope with it. Therefore, in this embodiment, the blow-through phenomenon is suppressed by using the adjustment of the intake air amount together.

In the present embodiment, the engine 20 is configured so that the operation timing and / or the operation lift amount of the intake valve 203 and / or the exhaust valve 204 can be changed. The blow-through adjustment control is executed by reducing the valve overlap period in which both the intake valve 203 and the exhaust valve 204 are open and / or the opening area of the intake valve 203 and / or the exhaust valve 204.
In the present embodiment, the limit calculation unit 105 and the limit control unit 106 execute the blow-by adjustment control by suppressing the intake pressure by the supercharger 30.

  Further, in the present embodiment, the injection calculation unit 102 sets the fuel injection timing during the exhaust stroke, and the injection control unit 103 that is an injection adjustment unit retards the fuel injection end timing set by the injection calculation unit 102. Thus, the ratio of the fuel injection amount during the intake stroke to the total fuel injection amount during one cycle is increased.

  The correspondence between the present disclosure and each specific example is as follows. An example of the injection control device in the present disclosure is the ECU 10. An example of the injection adjustment unit in the present disclosure is the injection calculation unit 102, the injection control unit 103, and the correction unit 104. An example of the restriction unit in the present disclosure is the restriction calculation unit 105 and the restriction control unit 106.

  The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Those in which those skilled in the art appropriately modify the design of these specific examples are also included in the scope of the present disclosure as long as they have the features of the present disclosure. Each element included in each of the specific examples described above and their arrangement, conditions, shape, and the like are not limited to those illustrated, and can be changed as appropriate. Each element included in each of the specific examples described above can be appropriately combined as long as no technical contradiction occurs.

  When a plurality of limiting means are provided, it is preferable to preferentially perform a limiting method in which the engine output is less likely to change. The reason why the injection rate improvement is preferentially executed in the present embodiment is that the influence of the change in the injection rate on the engine output is smaller than other restrictions. For example, when both the overlap limiting mechanism and the intake pressure limiting mechanism are provided in addition to the injection rate changing mechanism, the injection rate is first improved. If the fuel injection cannot be performed within the “ideal injection period”, the overlap limit is selected that is less likely to cause a decrease in engine output than the intake pressure limit. Further, if the intake pressure restriction is not used together, the intake pressure restriction should be performed only when the fuel injection cannot be performed within the “ideal injection period”.

  In the present embodiment, the correction unit 104 calculates the correction amount, but the injection end timing may be calculated. An example of the injection end timing calculation will be described with reference to FIG.

  In a port injection engine, as an emission countermeasure, the injection end timing is usually set before the intake stroke within a range that does not affect the air-fuel ratio controllability during transient operation, in order to ensure the time for fuel to evaporate before ignition. Set. An example of this injection end timing is BTDC 30 °.

  However, if an overlap state occurs in which the intake valve 203 and the exhaust valve 204 are both open in the supercharged state and near the TDC, the intake port fuel is blown through the exhaust port as it is pushed by the high intake pressure. On the contrary, the emission gets worse.

  Therefore, in the supercharging state, the injection end timing is set to be the intake stroke. During the intake stroke, the pressure in the cylinder decreases due to the lowering of the piston, so that the fuel sucked into the cylinder can be prevented from escaping to the exhaust port. However, it is not always preferable during the intake stroke, and it is preferable that the fuel injection is completed in the first half of the intake stroke in order to secure the vaporization time as much as possible.

  In the example shown in FIG. 7, the injection end timing is ta until the intake pressure is Pa. As described above, ta is BTDC 30 ° as an example. When the intake pressure reaches Pb, the injection end timing is set to tb. In an engine in which the emission deteriorates when the injection end timing is retarded from ATDC 120 °, tb and ATDC 120 ° are set. An example of the intake pressure Pb is 130 kPa. While the intake pressure changes from Pa to Pb, the injection end timing is set to change linearly from ta to tb.

  Next, another example of the injection end timing calculation will be described with reference to FIG. The blow-through phenomenon itself can occur regardless of the temperature in a supercharged state. However, since the fuel is less likely to vaporize as the temperature is lower, the fuel in the droplet state easily escapes to the exhaust port, increasing the risk of emission deterioration.

  Therefore, the injection end timing can be set based on the intake pressure and the temperature condition. In the example shown in FIG. 8, until the intake pressure is Pa, the injection end timing is ta regardless of the engine coolant temperature, and fuel injection is performed in the exhaust stroke. When the intake pressure is equal to or higher than Pb and the engine coolant temperature is lower than Tb, the injection end timing is set to tb, and fuel injection is performed in the intake stroke. As an example, fuel injection is performed in the intake stroke when the engine coolant temperature is 60 ° C. or lower and the intake pressure is 130 kPa or higher. In the case of the condition between the two boundary lines in FIG. 8, that is, when the intake air pressure is between Pa and Pb and the engine coolant temperature is Ta or less, and when the intake pressure is Pa or more and the engine coolant temperature is from Tb. In the case of Ta, the injection end timing is set to change linearly from ta to tb.

  In place of the intake pressure, a parameter having a correlation with the intake pressure, for example, an intake intake amount may be used. Further, the differential pressure between the intake pressure and the exhaust pressure (exhaust port pressure) may be measured or estimated. Further, the intake air temperature or the temperature of the lubricating oil may be used instead of the engine coolant temperature.

101: Necessity determination unit 102: Injection calculation unit (injection adjustment unit)
103: Injection control unit (injection adjustment unit)
104: Correction unit (injection adjustment unit)

Claims (11)

An injection control device,
Is it necessary to perform injection adjustment control that adjusts the amount and timing of fuel injection from the fuel injection valve to the intake port based on the intake pressure of the engine that can supply fuel by port injection and is equipped with a supercharger A necessity determination unit (101) for determining whether or not,
An injection adjustment unit (102, 103, 104) that executes the injection adjustment control based on the determination result of the necessity determination unit;
When the intake pressure is greater than or equal to a predetermined threshold intake pressure, the injection adjusting unit performs intake for the total fuel injection amount in one cycle compared to when the intake pressure is less than the threshold intake pressure. An injection control device that executes the injection adjustment control by increasing a ratio of a fuel injection amount during a stroke. The injection control device according to claim 1,
In the injection adjustment control, the injection adjustment unit is configured to increase a fuel injection amount in the first half during the intake stroke more than a fuel injection amount in the second half during the intake stroke. The injection control device according to claim 2,
In the fuel injection period, the injection adjustment unit is configured so that a sum of opening areas of the intake valve and the exhaust valve in a valve overlap period in which both the intake valve and the exhaust valve of the engine are both smaller than a threshold area. An injection control device that executes the injection adjustment control. The injection control device according to any one of claims 1 to 3,
The necessity determination unit determines whether the injection adjustment control is necessary based on the temperature of the engine,
The injection control unit is configured to perform the injection adjustment control when the temperature of the engine is lower than a predetermined threshold temperature. The injection control device according to any one of claims 1 to 4,
The injection control unit performs the injection adjustment control by increasing a fuel injection amount within a predetermined time. The injection control device according to claim 5,
The said injection adjustment part is an injection control apparatus which performs the said injection adjustment control by raising a fuel pressure. The injection control device according to claim 5,
The engine is provided with a plurality of fuel injection valves per cylinder,
The said injection adjustment part is an injection control apparatus which performs the said injection adjustment control by increasing the number of the said fuel injection valves to drive. The injection control device according to any one of claims 1 to 4,
Furthermore, a limiting unit (105, 106) for limiting the amount of intake air into the cylinder of the engine is provided,
The said restriction | limiting part is an injection control apparatus which performs the blow-off adjustment control which restrict | limits an intake air amount in parallel with the said injection adjustment control. The injection control device according to claim 8,
The engine is configured such that the operation timing and / or operation amount of the intake valve and / or the exhaust valve can be changed,
The restriction unit performs the blow-out adjustment control by reducing a valve overlap period in which both the intake valve and the exhaust valve are open and / or reducing an opening area of the intake valve and / or the exhaust valve. apparatus. The injection control device according to claim 8,
The said restriction | limiting part is an injection control apparatus which performs the said blow-by adjustment control by suppressing the intake pressure by the said supercharger. The injection control device according to any one of claims 1 to 10,
And an injection calculation unit (102) for calculating an injection end timing for ending the fuel injection from the fuel injection valve,
The injection calculation unit sets the fuel injection timing during the exhaust stroke,
The injection control device, wherein the injection adjustment unit increases the ratio of the fuel injection amount during the intake stroke to the total fuel injection amount during one cycle by retarding the fuel injection end time set by the injection calculation unit.

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