JP7180571B2 - Internal combustion engine and its control method - Google Patents

Description

The present disclosure relates to an internal combustion engine including a first fuel injection valve connected to a high pressure pump and a second fuel injection valve connected to a low pressure pump, and a control method thereof.

Conventionally, an exhaust purification unit that purifies the exhaust gas passing through the exhaust pipe of an internal combustion engine, an addition valve that injects (adds) fuel to the exhaust gas to regenerate the exhaust purification unit, and the fuel from the addition valve is introduced into the exhaust pipe. an introduction passage forming member that forms an introduction passage for the internal combustion engine; an addition control unit that controls the amount of fuel injected from the addition valve according to the operating conditions of the internal combustion engine; an air compression pump; An exhaust of an internal combustion engine, including a compression mechanism that takes in air from the exhaust port and supplies it into the introduction passage, and an air amount control unit that adjusts the amount of air supplied into the introduction passage from the compression mechanism according to the operating conditions of the internal combustion engine. Purifiers are known (see, for example, Patent Document 1). The air amount control unit of this exhaust purification device controls the compression mechanism so as to supply pressurized air into the introduction passage when the temperature of the introduction passage reaches a predetermined high temperature. Further, the addition control unit substantially synchronizes with the supply period of air in a state where the temperature of the introduction passage reaches a predetermined high temperature and reaches a regenerative temperature, and during a predetermined injection period shorter than the supply period, The addition valve is opened so as to inject fuel into the exhaust gas. As a result, the introduction passage forming member and the addition valve are cooled by the air taken in from the outside, and the adhering fuel is removed, and deposits that may accumulate as deposits on the opening side of the introduction passage into the exhaust pipe are removed from the exhaust pipe. blown away by

JP 2018-080705 A

According to the above-described conventional exhaust purification system for an internal combustion engine, the reliability of the exhaust purification system is improved by suppressing the change in the fuel injection amount from the addition valve over time, and the addition valve for preventing clogging of the injection hole Fuel consumption can be improved by suppressing the frequency of fuel injection. However, adding a compression mechanism including an air compression pump and a flow control valve to the internal combustion engine causes an increase in cost and weight of the internal combustion engine.

Therefore, the present disclosure is an internal combustion engine including a first fuel injection valve connected to a high-pressure pump and a second fuel injection valve connected to a low-pressure pump. The main purpose is to suppress the formation of deposits inside and outside the nozzle hole of the valve.

An internal combustion engine of the present disclosure includes a first fuel injection valve connected to a high-pressure pump and a second fuel injection valve connected to a low-pressure pump, wherein fuel injection from the second fuel injection valve is stopped. If the remaining amount of fuel in the sack portion and the injection hole of the second fuel injection valve after the injection is less than a predetermined threshold value, the pressure of the fuel supplied from the low pressure pump to the second fuel injection valve is reduced to the above A control device is provided for increasing the remaining amount as compared with the case where the remaining amount is equal to or greater than the threshold value.

In the control device for an internal combustion engine of the present disclosure, the residual amount of fuel in the sack portion and the nozzle hole of the second fuel injection valve is less than a predetermined threshold after the fuel injection from the second fuel injection valve is stopped. In this case, the pressure of the fuel supplied from the low-pressure pump to the second fuel injection valve is increased compared to when the remaining amount is equal to or greater than the threshold. As a result, while fuel is not being injected from the second fuel injection valve, the amount of fuel leakage (oil tightness) to the outside of the injection hole of the second fuel injection valve is reduced, and the sac portion and the inside of the injection hole are filled with fuel. can be kept As a result, it is possible to satisfactorily suppress the formation of deposits inside and outside the injection hole of the second fuel injection valve while suppressing an increase in cost and weight of the internal combustion engine.

Further, when the residual amount is less than the threshold, the control device increases the pressure of the fuel supplied from the low-pressure pump to the second fuel injection valve until the residual amount reaches the threshold. It may be higher than the necessary injection pressure required for the fuel injection from the valve. As a result, when the amount of fuel remaining in the sack portion and the injection hole of the second fuel injection valve is small, the leakage amount of fuel to the outside of the injection hole of the second fuel injection valve is reduced, and the sack portion and the injection hole are quickly injected. It is possible to fill the inside with fuel.

Further, when the remaining amount is equal to or greater than the threshold value, the control device may increase the pressure of the fuel supplied from the low-pressure pump to the second fuel injection valve so as to be required for the fuel injection from the second fuel injection valve. It may be lower than the required injection pressure. As a result, while fuel is not injected from the second fuel injection valve, the leakage amount of fuel (oil tightness) to the outside of the injection hole of the second fuel injection valve is minimized, and the injection hole of the second fuel injection valve is closed. It is possible to extremely well suppress the occurrence of deposits on the outside.

Further, the control device periodically injects fuel from the second fuel injection valve and starts the fuel injection from the second fuel injection valve even if the remaining amount has not reached the threshold value. The pressure of the fuel supplied from the low-pressure pump to the second fuel injection valve at the previous predetermined timing may be the required injection pressure. As a result, it becomes possible to properly inject fuel from the second fuel injection valve.

Further, the first fuel injection valve may be a fuel injection valve that supplies fuel to a combustion chamber of the internal combustion engine, and the second fuel injection valve injects fuel into an exhaust passage of the internal combustion engine. It may be a fuel addition valve that

The first fuel injection valve may be an in-cylinder injection valve that directly injects fuel into a combustion chamber of the internal combustion engine, and the second fuel injection valve injects fuel into an intake port of the internal combustion engine. It may be a port injection valve that

A method of controlling an internal combustion engine of the present disclosure includes a first fuel injection valve that injects fuel supplied from a high-pressure pump and a second fuel injection valve that injects fuel supplied from a low-pressure pump. After the fuel injection from the second fuel injection valve is stopped, if the remaining amount of fuel in the sack portion and the injection hole of the second fuel injection valve is less than a predetermined threshold value, the second The pressure of the fuel supplied to the fuel injection valve is increased compared to when the remaining amount is equal to or greater than the threshold value.

According to such a method, it is possible to satisfactorily suppress the formation of deposits inside and outside the injection hole of the second fuel injection valve while suppressing an increase in cost and weight of the internal combustion engine.

1 is a schematic configuration diagram showing an internal combustion engine of the present disclosure; FIG. FIG. 4 is an enlarged cross-sectional view showing a main part of a second fuel injection valve of the internal combustion engine of the present disclosure; 4 is a flow chart showing an example of a routine that is executed in the internal combustion engine of the present disclosure to suppress the formation of deposits inside and outside the nozzle hole of the second fuel injection valve; 4 is a time chart showing changes in pressure of fuel supplied from a low-pressure pump of an internal combustion engine of the present disclosure to a second fuel injection valve; FIG. 3 is a schematic configuration diagram showing another internal combustion engine of the present disclosure;

Next, a mode for carrying out the invention of the present disclosure will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram illustrating an engine 1 as an internal combustion engine of the present disclosure. The engine 1 shown in FIG. This is a diesel engine that converts the reciprocating motion of the piston 3 accompanying the combustion of fuel into the rotational motion of a crankshaft (not shown). As illustrated, the engine 1 includes an intake pipe 4, a throttle valve 5, an intake manifold 6, a plurality of intake valves 7, a plurality of in-cylinder injection valves (first fuel injection valves) 8, and a plurality of exhaust valves. It includes a valve 9 , an exhaust manifold 10 , an exhaust pipe 11 , a turbocharger (supercharger) 12 , an intercooler (cooler) 13 and an exhaust purification device 14 .

The throttle valve 5 is, for example, an electronically controlled throttle valve that can change the passage area in the intake pipe 4 . The intake manifold 6 is connected to the intake pipe 4 and the intake port of each combustion chamber 2 . The plurality of intake valves 7 open and close the intake ports of the corresponding combustion chambers 2, respectively. A plurality of in-cylinder injection valves 8 directly inject fuel into corresponding combustion chambers 2 . The plurality of exhaust valves 9 open and close the exhaust ports of the corresponding combustion chambers 2, respectively. However, instead of the in-cylinder injection valves 8, the engine 1 may be provided with port injection valves that inject fuel into corresponding intake ports. The exhaust manifold 10 is connected to the exhaust port of each combustion chamber 2 and the exhaust pipe 11 .

The turbocharger 12 includes a turbine T that is rotated by the exhaust gas flowing through the exhaust pipe 11 and a compressor C that is connected to the turbine T and compresses the air in the intake pipe 4 . The intercooler 13 cools the air flowing through the intake pipe 4 between the compressor C of the turbocharger 12 and the throttle valve 5 . The exhaust purification device 14 is incorporated in the exhaust pipe 11 on the downstream side of the turbine T of the turbocharger 12, and collects particulate matter in the exhaust gas on the downstream side of the oxidation catalyst (DOC) 14a and the oxidation catalyst 14a. and a particulate filter (DPF) 14b. However, the exhaust purification device 14 may include a NOx storage reduction catalyst (NSR catalyst) instead of the oxidation catalyst 14a.

Further, as shown in FIG. 1, the engine 1 includes a fuel tank 20 storing fuel such as light oil, a feed pump (low-pressure pump) 21, and a low-pressure fuel supply pipe LL connected to the discharge port of the feed pump 21. , a supply pump (high-pressure pump) 22 that pressurizes fuel from a feed pump 21, a high-pressure fuel supply pipe LH connected to the discharge port of the supply pump 22, a high-pressure fuel supply pipe LH, and a plurality of in-cylinder injection valves 8. It includes a connected common rail (accumulator) 23 and a fuel addition valve (second fuel injection valve) 80 connected to the low-pressure fuel supply pipe LL.

Feed pump 21 is an electric pump including a motor driven by power from an auxiliary battery (not shown). The feed pump 21 sucks the fuel in the fuel tank 20 and supplies it to the supply pump 22 and the low-pressure fuel supply pipe LL. The supply pump 22 is also an electric pump including a motor driven by power from the auxiliary battery. The supply pump 22 pressurizes the fuel from the feed pump 21 and supplies it to the common rail 23 through the high pressure fuel supply pipe LH. High-pressure fuel from the supply pump 22 is stored in a common rail 23 and supplied from the common rail 23 to each in-cylinder injection valve 8 . However, the feed pump 21 may be arranged in the fuel tank 20, and the supply pump 22 may be a mechanical pump driven by the engine 1, for example.

As shown in FIG. 2, the fuel addition valve 80 includes a nozzle body 81, a plurality of (for example, 6 to 8) injection holes 82 formed in the nozzle body 81, and each injection hole 82 communicating with the nozzle body 81. A sack portion (sack volume) 83 formed in the nozzle body 81, a needle 84 that opens and closes a passage (gap) that communicates the fuel reservoir (not shown) and the sack portion 83, and a needle 84 that moves back and forth in the axial direction (not shown). It is an electronically controlled solenoid valve including an electromagnetic drive mechanism. The fuel addition valve 80 is located upstream of the exhaust purification device 14, that is, between the turbine T of the turbocharger 12 and the exhaust purification device 14, so as to inject fuel into the exhaust gas in the exhaust pipe 11. can be attached to The low-pressure fuel supply pipe LL also includes a check valve 24 that regulates the flow of fuel from the fuel addition valve 80 side to the feed pump 21 (fuel tank 20) side. However, the fuel addition valve 80 may be attached to the exhaust manifold 10 or the exhaust pipe 11 so as to inject fuel into the exhaust gas upstream of the turbocharger 12 . A pressure accumulator may be arranged between the check valve 24 and the fuel addition valve 80 .

In addition, the engine 1 includes an electronic control unit (hereinafter referred to as "ECU") 50 that controls the entire engine. The ECU 50 includes a CPU (not shown), a ROM that stores various control programs, a RAM that temporarily stores data, a microcomputer including input ports and output ports, and various drive circuits. The ECU 50 acquires signals (physical quantities) from various sensors via an input port.

More specifically, the ECU 50 detects the rotation position (crank position) of the crankshaft detected by a crank position sensor (not shown), the valve body position (throttle position) of the throttle valve 5 detected by a throttle valve position sensor (not shown), The intake air amount of the engine 1 detected by an air flow meter not shown, the pressure in the intake pipe 4 (intake pipe pressure) detected by an intake pressure sensor (not shown), the coolant temperature Tw of the engine 1 detected by the water temperature sensor 60 , the fuel pressure PL in the low-pressure fuel supply pipe LL detected by the low-pressure fuel pressure sensor 61, the fuel pressure PH in the common rail 23 detected by the high-pressure fuel pressure sensor 62, and the exhaust purification device 14 detected by the exhaust temperature sensor 63. The temperature Tg of the exhaust gas flowing into the exhaust gas pressure sensor 64 and the pressure Pg of the exhaust gas flowing into the exhaust purification device 14 detected by the exhaust gas pressure sensor 64 are obtained. Based on the signals from these sensors, the ECU 50 generates control signals for valve mechanisms (not shown) that drive the throttle valve 5, the in-cylinder injection valves 8, the intake valves 7 and the exhaust valves 9, and the like. Control your equipment.

The ECU 50 also controls the feed pump 21 so that the fuel pressure PL in the low-pressure fuel supply pipe LL detected by the low-pressure fuel pressure sensor 61 reaches a predetermined target pressure PLtag. Further, the ECU 50 controls the supply pump 22 so that the pressure PH of the fuel in the common rail 23 detected by the high-pressure fuel pressure sensor 62 reaches a predetermined target pressure PHtag. In addition, the ECU 50 controls the fuel addition valve 80 so that fuel is injected (added) from the fuel addition valve 80 into the exhaust gas in the exhaust pipe 11 at predetermined intervals of time tint. As a result, the particulate matter trapped by the particulate filter 14b of the exhaust purification device 14 can be burned by utilizing the temperature rise of the exhaust gas due to the addition of fuel, and the particulate filter 14b can be regenerated. Further, when injecting fuel from the fuel addition valve 80 , the target pressure PLtag of the feed pump 21 is set to the required injection pressure Pinj required for fuel injection from the fuel addition valve 80 .

Here, by periodically injecting fuel from the fuel addition valve 80 as described above, clogging of the injection holes 82 of the fuel addition valve 80 due to deposits can be suppressed. However, when fuel is injected from the fuel addition valve 80 and adheres to the periphery of each injection hole 82 of the nozzle body 81 (see the two-dot chain line in FIG. 2), the adhering fuel, etc., is oxidized and becomes gum. Deposits may occur around the nozzle hole 82 . Based on this, in the engine 1, the ECU 50 executes the routine shown in FIG.

The routine of FIG. 3 is started when fuel injection from the fuel addition valve 80 is once completed (stopped). At the start of the routine of FIG. 3, the CPU (not shown) of the ECU 50 detects the fuel pressure PL in the low-pressure fuel supply pipe LL detected by the low-pressure fuel pressure sensor 61, the exhaust gas pressure Pg detected by the exhaust pressure sensor 64, and the fuel temperature. Tf is acquired (step S100). The fuel temperature Tf may be separately estimated based on the coolant temperature Tw detected by the water temperature sensor 60, and may be detected by a temperature sensor (not shown) installed in the fuel tank 20 or the like. There may be.

Next, the ECU 50 derives the remaining amount Vr of fuel in the sack portion 83 of the fuel addition valve 80 and all the injection holes 82 after the fuel injection based on the pressures PL, Pg and the fuel temperature Tf obtained in step S100 (step S110). In step S110, the ECU 50 acquires from a map (not shown) or an estimation formula created in advance through experiments and analyzes so as to define the relationship between the pressures PL, Pg and fuel temperature Tf, and the remaining amount Vr in step S100. Remaining amount Vr corresponding to pressures PL, Pg and fuel temperature Tf is derived.

After deriving the remaining amount Vr, the ECU 50 determines whether or not the remaining amount Vr is less than a predetermined threshold value Vt (step S120). The threshold value Vt is set when the sack portion 83 and the injection holes 82 are filled with fuel and the fuel does not protrude around the injection holes 82 due to surface tension (see FIG. 2). It is the amount of fuel present and is calculated through experiments and analyses. If it is determined in step S120 that the remaining amount Vr is less than the threshold Vt (step S120: YES), the ECU 50 acquires the difference ΔV (=Vt−Vr) between the threshold Vt and the remaining amount Vr in step S100. The high pressure holding time tu is derived based on the exhaust gas pressure Pg obtained (step S130).

The high pressure holding time tu is set after the target pressure PLtag of the feed pump 21 is set to a high pressure value Phigh (Phigh>Pinj) higher than the required injection pressure Pinj, and the amount of fuel in the sack portion 83 and all the injection holes 82 reaches the threshold value Vt. is the time required to reach Also, the high pressure value Phigh is calculated in advance through experiments and analyses. In step S130, the ECU 50 obtains the difference ΔV and step S100 from a map (not shown) or an estimation formula created in advance through experiments and analyzes so as to define the relationship between the difference ΔV and the pressure Pg and the high pressure holding time tu. A high pressure holding time tu corresponding to the pressure Pg obtained is derived.

Further, the ECU 50 determines that the high pressure holding time tu derived in step S130 is the predetermined timing for setting the target pressure PLtag of the feed pump 21 to the required injection pressure Pinj before the next fuel injection from the fuel addition valve 80. It is determined whether or not the remaining time trem is equal to or less (step S140). The predetermined timing is, for example, a predetermined time .DELTA.t before the next fuel injection timing of the fuel addition valve 80, and in this case, trem=tint-.DELTA.t. When it is determined in step S140 that the high pressure holding time tu is equal to or less than the remaining time trem (step S140: YES), the ECU 50 sets the high pressure holding time tu to the judgment time tref (step S150). If it is determined in step S140 that the high pressure holding time tu is longer than the remaining time trem (step S140: NO), the ECU 50 sets the remaining time trem to the determination time tref (step S155).

After the process of step S150 or S155, the ECU 50 sets the target pressure PLtag of the feed pump 21 to the high pressure value Phigh, and controls the feed pump 21 so that the target pressure PLtag becomes the high pressure value Phigh (step S160). Further, the ECU 50 determines whether or not the elapsed time from the start of the processing of step S160 has reached the determination time tref (step S170), and until the elapsed time reaches the determination time tref (step S170: NO). The processes of steps S160 and S170 are repeatedly executed. As a result, the fuel from the feed pump 21 flows into the sack portion 83 and the injection holes 82 through a slight gap formed between the valve seat of the nozzle body 81 and the needle 84 when the fuel addition valve 80 is fully closed. filled inside.

When it is determined in step S170 that the elapsed time has reached the determination time tref (step S170: YES), the ECU 50 sets the target pressure PLtag of the feed pump 21 to the required injection pressure Pinj, and sets the target pressure PLtag to the required injection pressure Pinj. The feed pump 21 is controlled so as to reach the pressure Pinj (step S180). Further, the ECU 50 determines whether or not the next fuel injection timing for the fuel addition valve 80 has arrived (step S190), and until the next fuel injection timing has arrived (step S190: NO), step S180 and step S190 are executed. repeats the process of Then, when the next fuel injection timing arrives, the ECU 50 controls the fuel addition valve 80 so as to inject (add) fuel to the exhaust gas in the exhaust pipe 11 for a predetermined time (step S200). , the routine of FIG. 3 is executed again.

On the other hand, if it is determined in step S120 that the remaining amount Vr is equal to or greater than the threshold value Vt (step S120: NO), the ECU 50 sets the target pressure PLtag of the feed pump 21 to a low pressure value Plow ( Plow>Pinj), and the feed pump 21 is controlled so that the target pressure PLtag becomes the low pressure value Plow (step S210). The low pressure value Plow is calculated in advance through experiments and analyses, as a pressure that prevents the remaining amount Vr from becoming less than the threshold value Vt. Further, the ECU 50 determines whether or not the elapsed time from the start of the processing of step S210 has reached the remaining time trem (step S220), and waits until the elapsed time reaches the remaining time trem (step S220: NO). , steps S210 and S220 are repeatedly executed. If it is determined in step S220 that the elapsed time has reached the remaining time tref (step S220: YES), the ECU 50 executes the processes of steps S180 to S200 described above, and after the fuel injection is completed, routine.

As a result of executing the above-described routine of FIG. In some cases (time t1 in FIG. 4), the pressure of the fuel supplied from the feed pump 21 to the fuel addition valve 80 remains constant until the residual amount Vr reaches the threshold value Vt (time t2 in FIG. 4). It is higher than the required injection pressure Pinj required for fuel injection. As a result, when the amount of remaining fuel Vr in the sack portion 83 and all the injection holes 82 of the fuel addition valve 80 is small, the amount of fuel leakage (oil tightness) outside the injection holes 82 of the fuel addition valve 80 is reduced. In addition, the sack portion 83 and the injection holes 82 can be quickly filled with fuel. As a result, for example, a device for blowing away the deposits to the rear stage side is not required, so the increase in cost and weight of the engine 1 can be suppressed, and deposits can be prevented from occurring inside and outside the injection holes 82 of the fuel addition valve 80. It is possible to suppress it satisfactorily.

Further, in the engine 1, fuel is periodically injected from the fuel addition valve 80 (time t3-t4, t6-t7 in FIG. 4), and before starting (resuming) fuel injection from the fuel addition valve 80 ( At times t2, t5, and t8 in FIG. 4), the pressure of the fuel supplied from the feed pump 21 to the fuel addition valve 80 is set to the required injection pressure Pinj. That is, in the engine 1, when the high pressure holding time tu is longer than the remaining time trem (see the dashed line in FIG. 4), even if the remaining amount Vr has not reached the threshold value Vt, the feed is fed when the remaining time trem has passed. The target pressure PLtag of the pump 21 is set to the required injection pressure Pinj. As a result, the fuel can be properly injected from the fuel addition valve 80 at all times.

Furthermore, when the remaining fuel amount Vr is equal to or greater than the threshold (time t7 in FIG. 4), the pressure of the fuel supplied from the feed pump 21 to the fuel addition valve 80 is lowered below the required injection pressure Ping. As a result, while fuel is not injected from the fuel addition valve 80, the amount of fuel leakage (oil tightness) to the outside of each injection hole 82 is minimized, and deposits outside each injection hole 82 of the fuel addition valve 80 are reduced. It is possible to suppress the occurrence of such defects extremely well.

As described above, the engine 1 includes a plurality of in-cylinder injection valves (first fuel injection valves) 8 connected to the supply pump (high pressure pump) 22 and a fuel addition valve connected to the feed pump (low pressure pump) 21 . A valve (second fuel injection valve) 80 and an ECU 50 are included. Then, the ECU 50 determines if the remaining fuel amount Vr in the sack portion 83 and all the injection holes 82 after the fuel injection from the fuel addition valve 80 is stopped is less than the predetermined threshold value Vt (step S120 in FIG. 3: YES), the pressure of the fuel supplied from the feed pump 21 to the fuel addition valve 80 is increased compared to when the residual amount Vr is equal to or greater than the threshold value Vt (steps S130 to S170 in FIG. 3). As a result, while fuel is not being injected from the fuel addition valve 80, the amount of fuel leakage (oil tightness) to the outside of each injection hole 82 is reduced, and the sack portion 83 and all the injection holes 82 are filled with fuel. be able to. As a result, it is possible to satisfactorily suppress the formation of deposits inside and outside each injection hole 82 of the fuel addition valve 80 while suppressing an increase in the cost and weight of the engine 1 .

FIG. 5 is a schematic configuration diagram showing an engine 1B, which is another internal combustion engine of the present disclosure. Among the constituent elements of the engine 1B, the same elements as those of the engine 1 described above are denoted by the same reference numerals, and overlapping descriptions are omitted.

The engine 1B shown in FIG. 5 burns a mixture of gasoline and air as fuel in a plurality of (for example, four) combustion chambers 2, and the reciprocating motion of pistons 3 associated with the combustion of the mixture is driven by a crankshaft (illustrated). Omitted) is a gasoline engine that converts to rotary motion. The engine 1B also includes a plurality of port injection valves 8p for injecting fuel into corresponding intake ports, a plurality of in-cylinder injection valves 8d for directly injecting fuel into the corresponding combustion chambers 2, and A plurality of installed spark plugs 15, an exhaust purification device 14B including a NOx storage type exhaust purification catalyst (three-way catalyst) that purifies harmful components such as CO (carbon monoxide), HC, and NOx in exhaust gas, and exhaust gas and a particulate filter (GPF) 16 that collects particulate matter (fine particles) therein. In the engine 1B, at least each port injection valve 8p has the same structure as the fuel addition valve 80 described above.

Furthermore, the engine 1B is connected to a low-pressure delivery pipe 23L connected to a feed pump (low-pressure pump) 21 via a low-pressure fuel supply pipe LL, and to a supply pump (high-pressure pump) 22 via a high-pressure fuel supply pipe LH. high pressure delivery pipe 23H. A fuel inlet of each port injection valve 8p is connected to the low-pressure delivery pipe 23L, and a fuel inlet of each in-cylinder injection valve 8d is connected to the high-pressure delivery pipe 23H. Feed pump 21 is an electric pump including a motor driven by power from an auxiliary battery (not shown). The fuel from the feed pump 21 is stored in the low pressure delivery pipe 23L and supplied from the low pressure delivery pipe 23L to each port injection valve 8p. The supply pump 22 is, for example, a piston pump (mechanical pump) driven by the engine 1 . High-pressure fuel from the supply pump 22 is stored in the high-pressure delivery pipe 23H and supplied from the high-pressure delivery pipe 23H to the in-cylinder injection valves 8d.

In such an engine 1B, when the load (required power) of the engine 1 is equal to or less than a predetermined value, fuel is injected from each port injection valve 8p and fuel injection from each in-cylinder injection valve 8d is stopped. Further, when the load of the engine 1B exceeds a predetermined value, fuel injection from each port injection valve 8p is stopped and fuel is injected from each in-cylinder injection valve 8d. In engine 1B, the time during which fuel injection from each port injection valve 8p is stopped is longer than the time during which fuel injection from each in-cylinder injection valve 8d is stopped. For this reason, the ECU 50B of the engine 1B, while fuel is being injected from each of the in-cylinder injection valves 8d, periodically releases fuel from each of the port injection valves 8p in order to suppress clogging due to deposits in injection holes (not shown) of each of the port injection valves 8p. to inject fuel. In the engine 1B, the ECU 50B executes a routine similar to that shown in FIG. 3 for each of the plurality of port injection valves 8p while fuel is being injected from each in-cylinder injection valve 8d. This eliminates the need for, for example, a device for blowing off deposits to the rear stage side, thereby suppressing an increase in the cost and weight of the engine 1B while effectively preventing deposits from occurring inside and outside the injection holes of the port injection valves 8p. can be suppressed to

It goes without saying that the invention of the present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment is merely one specific form of the invention described in the Summary of the Invention column, and does not limit the elements of the invention described in the Summary of the Invention column.

INDUSTRIAL APPLICABILITY The invention of the present disclosure can be used in the manufacturing industry of internal combustion engines and the like.

1, 1B engine, 2 combustion chamber, 3 piston, 4 intake pipe, 5 throttle valve, 6 intake manifold, 7 intake valve, 8, 8d in-cylinder injection valve (first fuel injection valve), 8p port injection valve (second fuel injection valve), 80 fuel addition valve (second fuel injection valve), 81 nozzle body, 82 injection hole, 83 sack portion, 84 needle, 9 exhaust valve, 10 exhaust manifold, 11 exhaust pipe, 12 turbocharger, 13 intercooler , 14, 14B exhaust purification device, 14a oxidation catalyst, 14b, 16 particulate filter, 15 spark plug, 20 fuel tank, 21 feed pump, 22 supply pump, 23 common rail, 23H high pressure delivery pipe, 23L low pressure delivery pipe, 24 reverse stop valve, 50, 50B electronic control unit (ECU), 60 water temperature sensor, 61 low pressure fuel pressure sensor, 62 high pressure fuel pressure sensor, 63 exhaust temperature sensor, 64 exhaust pressure sensor, C compressor, LL low pressure fuel supply pipe, LH high pressure fuel supply tube, T turbine.

Claims (7)

An internal combustion engine including a first fuel injection valve connected to a high pressure pump and a second fuel injection valve connected to a low pressure pump,
After the fuel injection from the second fuel injection valve is stopped, if the remaining amount of fuel in the sack portion and the injection hole of the second fuel injection valve is less than a predetermined threshold value, the second An internal combustion engine comprising a control device that increases the pressure of fuel supplied to a fuel injection valve compared to when the remaining amount is equal to or greater than the threshold. The internal combustion engine of claim 1,
When the remaining amount is less than the threshold, the control device increases the pressure of the fuel supplied from the low-pressure pump to the second fuel injection valve until the remaining amount reaches the threshold. an internal combustion engine that is higher than the required injection pressure required for said fuel injection. In the internal combustion engine according to claim 1 or 2,
When the remaining amount is equal to or greater than the threshold value, the control device increases the pressure of fuel supplied from the low-pressure pump to the second fuel injection valve so as to be required for the fuel injection from the second fuel injection valve. An internal combustion engine that is lower than the injection pressure. In the internal combustion engine according to claim 2 or 3,
The control device periodically injects fuel from the second fuel injection valve, and even if the remaining amount has not reached the threshold value, before starting the fuel injection from the second fuel injection valve An internal combustion engine in which the pressure of fuel supplied from the low-pressure pump to the second fuel injection valve at a predetermined timing is set to the required injection pressure. In the internal combustion engine according to any one of claims 1 to 4,
The first fuel injection valve is a fuel injection valve that supplies fuel to a combustion chamber of the internal combustion engine, and the second fuel injection valve is a fuel addition valve that injects fuel into an exhaust passage of the internal combustion engine. An internal combustion engine. In the internal combustion engine according to any one of claims 1 to 4,
The first fuel injection valve is an in-cylinder injection valve that directly injects fuel into a combustion chamber of the internal combustion engine, and the second fuel injection valve is a port injection valve that injects fuel into an intake port of the internal combustion engine. An internal combustion engine. A control method for an internal combustion engine including a first fuel injection valve that injects fuel supplied from a high-pressure pump and a second fuel injection valve that injects fuel supplied from a low-pressure pump,
After the fuel injection from the second fuel injection valve is stopped, if the remaining amount of fuel in the sack portion and the injection hole of the second fuel injection valve is less than a predetermined threshold value, the second A control method for an internal combustion engine, wherein the pressure of fuel supplied to a fuel injection valve is increased compared to when the remaining amount is equal to or greater than the threshold value.

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