JP2018025177A - Control method and control system for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately determine whether control to burn out deposits accumulated in a combustion chamber can be executed or not, on the basis of an engine speed.SOLUTION: In a control system for a diesel engine including a fuel injection valve 20 for injecting fuel directly into a combustion chamber 17, a control device 60 determines whether deposits are accumulated in the combustion chamber 17 or not, finds a relationship between the engine speed and a practicable ignition timing limit and a required ignition timing for burning out the deposits accumulated in the combustion chamber, on the basis of the operating condition of an engine E, and then sets a minimum engine speed so that the ignition timing limit satisfies the required ignition timing. Then, when determining that the deposits are accumulated, if a current engine speed is not lower than the minimum engine speed, the control device 60 performs control to further advance a fuel injection timing for the fuel injection valve 20 than when not determining that the deposits are accumulated.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a control method and control system for a diesel engine including a fuel injection valve that directly injects fuel into a combustion chamber.

  Conventionally, as a method of removing deposits accumulated in a cylinder of a diesel engine, for example, there is a method described in Patent Document 1. In the method described in Patent Document 1, the concept of “heat generation rate centroid position” is introduced as an index value representing the combustion state of the engine, and the heat generation rate centroid position at which the sum of the cooling loss and the exhaust loss is minimized. The crank angle is set as the reference crank angle. Then, when a deposit of a certain amount or more is accumulated on the top land of the piston, the heat generation rate gravity center position is advanced from the reference crank angle (corresponding to substantially advance the fuel injection timing), thereby The deposit is burnt down by raising the temperature of the piston top land.

JP 2016-14380 A

  By the way, in order to properly burn the deposit accumulated in the combustion chamber, the fuel is ignited at a desired advance timing in order to raise the in-cylinder temperature to a temperature sufficient to burn the deposit ( Such ignition timing is hereinafter referred to as “required ignition timing”), and it is necessary to advance the fuel injection timing appropriately. On the other hand, the ignition timing limit on the advance side that can be realized in the engine changes according to the engine speed. Specifically, in a relatively low engine speed range, the ignition timing limit tends to be retarded as the engine speed decreases. For this reason, when the engine speed is lowered, the ignition timing limit becomes more retarded than the required ignition timing, and the fuel may not be ignited at the required ignition timing. In this case, the in-cylinder temperature cannot be raised appropriately, and the deposit accumulated in the combustion chamber cannot be burned out.

  From the above, from the viewpoint of the required ignition timing and the ignition timing limit, it is desirable to appropriately determine the engine speed and determine whether or not to execute the control for burning the deposit accumulated in the combustion chamber. Patent Document 1 described above does not describe any consideration of the engine speed in executing the control.

  The present invention has been made to solve the above-described problems of the prior art, and appropriately determines whether or not to execute control for burning out deposits accumulated in the combustion chamber based on the engine speed. It is an object to provide a control method and a control system of a diesel engine capable of performing the above.

In order to achieve the above object, the present invention provides a method for controlling a diesel engine having a fuel injection valve that directly injects fuel into a combustion chamber, and determines whether deposits are accumulated in the combustion chamber. A step of controlling the fuel injection amount and fuel injection timing of the fuel injection valve based on the required torque when the vehicle travels, and an engine speed and a possible advance side ignition timing limit based on the operating state of the diesel engine, And a process for setting the minimum engine speed at which the advance side ignition timing limit satisfies the required ignition timing, and the deposit is accumulated. If the current engine speed exceeds the minimum engine speed when the vehicle is being serviced and not running, the fuel injection valve The injection timing, and a step of performing control to also be advanced from the fuel injection timing at the same engine speed and the same torque required during running of the vehicle, characterized in that.
According to the present invention configured as described above, the relationship between the engine speed and the advanceable ignition timing limit on the advance side (advance side ignition timing limit) is obtained based on the operating state of the engine, and the combustion chamber The required ignition timing to be applied to burn the deposit deposited on the engine is determined, and the minimum engine speed that satisfies the required ignition timing is set. Then, when it is determined that deposits are accumulated, control is performed to advance the fuel injection timing only when the current engine speed is equal to or higher than the minimum engine speed. Thereby, the required ignition timing or the ignition timing on the more advanced side than that can be appropriately realized by the control for advancing the fuel injection timing. Therefore, according to the present invention, the in-cylinder temperature can be raised and the deposit accumulated in the combustion chamber can be appropriately burned out.
In addition, when the control for advancing the fuel injection timing as described above is performed during actual vehicle travel, a sense of incongruity (especially noise) may occur. However, according to the present invention, the control is performed on the vehicle. Since it is performed during maintenance and non-running, the occurrence of such a sense of incongruity can be appropriately suppressed.

In the present invention, preferably, the diesel engine further includes a supercharger driven by the diesel engine, and the minimum engine speed is set to a lower speed as the supercharging pressure by the supercharger is higher.
According to the present invention configured as described above, considering that the ignition environment in the combustion chamber is improved when the supercharging pressure by the supercharger is high, the minimum engine speed is decreased as the supercharging pressure is increased. Set to the number of revolutions. Thereby, the appropriate minimum engine speed according to the supercharging pressure can be set. In this case, regarding the control for advancing the fuel injection timing, the execution permission range defined by the engine speed can be expanded.

In the present invention, preferably, the minimum engine speed is set to a higher speed as the fuel injection amount of the fuel injection valve is larger.
According to the present invention configured as described above, in view of the fact that if the fuel injection amount is large, it is necessary to increase the engine speed and increase the boost pressure in order to improve the ignition environment. The larger the quantity, the higher the minimum engine speed is set. Thereby, an appropriate minimum engine speed according to the fuel injection amount can be set. In this case, with respect to the control for advancing the fuel injection timing, the execution permission range defined by the engine speed can be narrowed to appropriately ensure the required ignition timing or the ignition timing more advanced than that. .

In the present invention, the vehicle preferably includes an auxiliary machine driven by a diesel engine, and the minimum engine speed is lower as the auxiliary machine driving resistance applied to the diesel engine to drive the auxiliary machine is higher. Set to a number.
According to the present invention configured as described above, it is possible to drive the auxiliary machine in consideration of the fact that when the auxiliary machine driving resistance is high, the amount of fuel injection applied at the same engine speed increases and the in-cylinder gas temperature rises. As the resistance increases, the minimum engine speed is set to a lower speed. Thereby, the appropriate minimum engine speed according to auxiliary machine drive resistance can be set. In this case, regarding the control for advancing the fuel injection timing, the execution permission range defined by the engine speed can be expanded.

In another aspect, in order to achieve the above object, the present invention is a diesel engine control system comprising a fuel injection valve that directly injects fuel into a combustion chamber and a control device that controls the fuel injection valve. The control device determines whether or not deposits are accumulated in the combustion chamber, controls the fuel injection amount and fuel injection timing of the fuel injection valve based on the required torque when the vehicle travels, and based on the operating state of the diesel engine, The relationship between the engine speed and the achievable advance side ignition timing limit, and the required ignition timing to burn off deposits deposited in the combustion chamber, are determined. The minimum advance side ignition timing limit satisfies the required ignition timing. When the engine speed is set and it is determined that the deposit is accumulated, the current engine speed is the minimum engine speed when the vehicle is being serviced and not running. The fuel injection timing of the fuel injection valve is controlled so as to advance from the fuel injection timing at the same engine speed and the same required torque when the vehicle is running. And
Also according to the present invention configured as described above, the required ignition timing or the ignition timing more advanced than that can be appropriately realized by the control for advancing the fuel injection timing, and the in-cylinder temperature is increased to increase the in-cylinder temperature. It is possible to appropriately burn off the deposit deposited on the substrate.

In the present invention, preferably, the diesel engine further includes a supercharger driven by the diesel engine, and the control device sets the minimum engine speed to a lower speed as the supercharging pressure by the supercharger is higher. To do.
According to the present invention configured as described above, an appropriate minimum engine speed can be set according to the supercharging pressure.

In the present invention, preferably, the control device sets the minimum engine speed to a higher speed as the fuel injection amount of the fuel injection valve increases.
According to the present invention configured as described above, it is possible to set an appropriate minimum engine speed corresponding to the fuel injection amount.

In the present invention, preferably, the vehicle includes an auxiliary machine driven by a diesel engine, and the control device increases the minimum engine rotational speed as the auxiliary machine driving resistance applied to the diesel engine to drive the auxiliary machine increases. Set to a lower speed.
According to the present invention configured as described above, it is possible to set an appropriate minimum engine speed corresponding to the accessory driving resistance.

  According to the control method and control system for a diesel engine according to the present invention, it is possible to appropriately determine whether or not the control for burning the deposit accumulated in the combustion chamber can be performed based on the engine speed.

1 is a schematic configuration diagram of an engine system according to an embodiment of the present invention. It is a block diagram which shows the electric constitution of the control apparatus by embodiment of this invention. It is an expanded sectional view of the fuel injection valve by this embodiment of the present invention. It is explanatory drawing about the minimum rotation speed applied in embodiment of this invention, and an upper limit rotation speed. It is explanatory drawing about the relationship between an engine speed and a combustion period. It is a time chart at the time of performing deposit sintering control by embodiment of this invention. It is a flowchart which shows the main control by embodiment of this invention. It is a flowchart which shows the deposit accumulation determination process by embodiment of this invention. It is a flowchart which shows the deposit burnout control by embodiment of this invention.

  Hereinafter, a control method and a control system of a diesel engine according to an embodiment of the present invention will be described with reference to the accompanying drawings.

<System configuration>
First, a system to which a control method and control system for a diesel engine according to an embodiment of the present invention is applied will be described with reference to FIGS. 1 and 2. Specifically, FIG. 1 is a schematic configuration diagram of an engine system according to an embodiment of the present invention, and FIG. 2 is a block diagram showing an electrical configuration of a control device according to the embodiment of the present invention.

  As shown in FIG. 1, the engine system 200 mainly includes an engine E as a diesel engine, an intake system IN that supplies intake air to the engine E, a fuel supply system FS that supplies fuel to the engine E, It has an exhaust system EX that exhausts exhaust gas of the engine E, and sensors 101 to 122 that detect various states relating to the engine system 200.

  First, the intake system IN has an intake passage 1 through which intake air passes, and an air cleaner 3 that purifies air introduced from the outside in order from the upstream side, and intake air that passes through the intake passage 1. The compressor 5a of the turbocharger 5 that compresses and raises the intake pressure, the intake shutter valve 7 that adjusts the flow rate of the intake air that passes through, and the water-cooled intercooler that cools the intake air using the coolant that has passed through 8, a water pump 9 that controls the flow rate of the cooling water flowing through the intercooler 8, and a cooling water passage 10 that connects the intercooler 8 and the water pump 9 and circulates the cooling water therebetween. And a surge tank 12 for temporarily storing the intake air supplied to the engine E.

  In the intake system IN, an air flow sensor 101 for detecting the intake air amount and an intake air temperature sensor 102 for detecting the intake air temperature are provided on the intake passage 1 immediately downstream of the air cleaner 3. 5 is provided with a turbo rotational speed sensor 103 for detecting the rotational speed (turbo rotational speed) of the compressor 5a, and the intake shutter valve 7 is provided with an intake shutter for detecting the opening degree of the intake shutter valve 7. A valve position sensor 105 is provided, and an intake air temperature sensor 106 for detecting the intake air temperature and an intake air pressure sensor 107 for detecting the intake air pressure are provided on the intake passage 1 immediately downstream of the intercooler 8. Is provided with an intake manifold temperature sensor 108. Various sensors 101 to 103 and 105 to 108 provided in the intake system IN output detection signals S101 to S103 and S105 to S108 corresponding to the detected parameters, respectively, to the control device 60 (see FIG. 2).

Next, the engine E includes an intake valve 15 that introduces intake air supplied from the intake passage 1 (specifically, an intake manifold) into the combustion chamber 17, a fuel injection valve 20 that directly injects fuel into the combustion chamber 17, The glow plug 21 as an auxiliary heat source for ensuring ignitability at the time of cold start or the like, the piston 23 reciprocating by combustion of the air-fuel mixture in the combustion chamber 17, and the reciprocating motion of the piston 23 are rotated. A crankshaft 25 and an exhaust valve 27 for discharging exhaust gas generated by combustion of the air-fuel mixture in the combustion chamber 17 to the exhaust passage 41 are provided. Further, the engine E is provided with an alternator 26 that generates electric power using the output of the engine E. The electric power generated by the alternator 26 is supplied to a battery (not shown), and this electric power is supplied to various auxiliary machines (for example, the rear differential 141 and the headlight 142) in the vehicle to drive the various auxiliary machines.
The fuel injection valve 20 includes a plurality of injection holes on the injection surface, that is, is configured as a multi-hole type, and injects fuel from these injection holes in a plurality of directions. In addition, the glow plug 21 is disposed so that the heat generating portion provided in the combustion chamber 17 is positioned between the plurality of sprays from the plurality of nozzle holes of the fuel injection valve 20. That is, the heat generating part of the glow plug is disposed at a position where it does not directly contact the fuel spray. By doing so, problems (such as failure of the glow plug 21) due to the direct application of fuel to the heat generating portion of the glow plug 21 are prevented. Basically, when the glow plug 21 is energized, the heat generating portion generates heat, and combustion starts in the cylinder using this heat as a heat source. And the in-cylinder pressure rises by this combustion, and the ignitability in the whole cylinder is ensured.

  Further, the engine E includes a cooling water temperature sensor 109 that detects the temperature (water temperature) of cooling water that cools the engine E and the like, a crank angle sensor 110 that detects the crank angle of the crankshaft 25, and hydraulic pressure and / or oil. An oil pressure / oil temperature sensor 111 for detecting the temperature and an optical oil level sensor 112 for detecting the oil level are provided. These various sensors 109 to 112 provided in the engine E output detection signals S109 to S112 corresponding to the detected parameters to the control device 60, respectively.

Next, the fuel supply system FS includes a fuel tank 30 for storing fuel, and a fuel supply passage 38 for supplying fuel from the fuel tank 30 to the fuel injection valve 20. In the fuel supply passage 38, a low-pressure fuel pump 31, a high-pressure fuel pump 33, and a common rail 35 are provided in order from the upstream side. The low pressure fuel pump 31 is provided with a fuel warmer 32, the high pressure fuel pump 33 is provided with a fuel pressure regulator 34, and the common rail 35 is provided with a common rail pressure reducing valve 36.
In the fuel supply system FS, the high-pressure fuel pump 33 is provided with a fuel temperature sensor 114 that detects the fuel temperature, and the common rail 35 is provided with a fuel pressure sensor 115 that detects the fuel pressure. These various sensors 114 and 115 provided in the fuel supply system FS output detection signals S114 and S115 corresponding to the detected parameters to the control device 60, respectively.

  Next, the exhaust system EX has an exhaust passage 41 through which the exhaust gas passes. The exhaust passage 41 is rotated by the exhaust gas passing through the exhaust passage 41 in order from the upstream side. A turbine 5b of the turbocharger 5 that drives the compressor 5a, a diesel oxidation catalyst (DOC) 45 having a purification function of exhaust gas, and a diesel particulate filter (DPF) as a filter device 46 and an exhaust shutter valve 49 for adjusting the exhaust flow rate passing therethrough are provided. The DOC 45 is a catalyst that oxidizes hydrocarbon (HC), carbon monoxide (CO), and the like using oxygen in the exhaust gas to change it into water and carbon dioxide, and the DPF 46 is a particulate substance ( It is a filter that collects PM (Particulate Matter).

In the exhaust system EX, an exhaust pressure sensor 116 for detecting the exhaust pressure and an exhaust temperature sensor 117 for detecting the exhaust temperature are provided on the exhaust passage 41 on the upstream side of the turbine 5b of the turbocharger 5. Exhaust temperature sensors 118 and 119 for detecting the exhaust temperature are respectively provided immediately upstream of the DOC 45 and between the DOC 45 and the DPF 46. On the exhaust passage 41 near the DPF 46, upstream and downstream of the DPF 46 are provided. A DPF differential pressure sensor 120 for detecting a difference in exhaust pressure with respect to the exhaust side (hereinafter referred to as “DPF differential pressure”) is provided, and a linear for detecting oxygen concentration is provided on the exhaust passage 41 immediately downstream of the DPF 46. An O ₂ sensor 121 and an exhaust temperature sensor 122 for detecting the exhaust temperature are provided. These various sensors 116 to 122 provided in the exhaust system EX output detection signals S116 to S122 corresponding to the detected parameters to the control device 60, respectively.

  The turbocharger 5 is configured in a small size so that the turbocharging can be performed efficiently even at low speed rotation with low exhaust energy. The turbocharger 5 is provided with a plurality of movable flaps 5c so as to surround the entire circumference of the turbine 5b, and these flaps 5c change the flow cross-sectional area (nozzle cross-sectional area) of the exhaust gas to the turbine 5b. This is configured as a variable geometry turbocharger (VGT). For example, the flap 5c is rotated by an actuator with the magnitude of the negative pressure acting on the diaphragm adjusted by an electromagnetic valve. Further, a VGT opening sensor 104 is provided for detecting the opening of the flap 5c (which is the flap opening, hereinafter referred to as “VGT opening” as appropriate) depending on the position of the actuator. The VGT opening sensor 104 outputs a detection signal S104 corresponding to the detected VGT opening to the control device 60.

  Further, the engine system 200 includes a high pressure EGR device 43 and a low pressure EGR device 48. The high-pressure EGR device 43 connects the exhaust passage 41 upstream of the turbine 5b of the turbocharger 5 and the intake passage 1 downstream of the compressor 5b of the turbocharger 5 (specifically, downstream of the intercooler 8). And a high pressure EGR valve 43b that adjusts the flow rate of exhaust gas that passes through the high pressure EGR passage 43a. The low pressure EGR device 48 includes an exhaust passage 41 on the downstream side of the turbine 5b of the turbocharger 5 (specifically, on the downstream side of the DPF 46 and the upstream side of the exhaust shutter valve 49) and the upstream side of the compressor 5b of the turbocharger 5. A low pressure EGR passage 48a that connects the intake passage 1 of the engine, a low pressure EGR cooler 48b that cools the exhaust gas that passes through the low pressure EGR passage 48a, and a low pressure EGR valve 48c that adjusts the flow rate of the exhaust gas that passes through the low pressure EGR passage 48a. And a low pressure EGR filter 48d.

  Next, referring to FIG. 2, in addition to the detection signals S101 to S122 of the various sensors 101 to 122 shown in FIG. 1, the control device 60 detects an outside air temperature sensor 98 that detects the outside air temperature, and detects the atmospheric pressure. Detection signals S98 to S100 output from the pressure sensor 99 and the accelerator opening sensor 100 that detects the opening (accelerator opening) of the accelerator pedal 95 are input. Further, the control device 60 switches on / off the rear differential 141 (formally “rear defogger”, but the term “rear def” is generally used as an abbreviation in this specification). The rear differential switch 94, the headlight switch 95 for switching on / off of the headlight 142, the air conditioner switch 96 for switching on / off of the air conditioner, and the air volume changeover switch 97 for switching the air volume of the air conditioner are output. The received signals S94 to S97 are input.

  The control device 60 includes at least a PCM (Power-train Control Module), and controls various components in the vehicle based on the signals S94 to S122 described above. Specifically, the control device 60 controls a control signal for an actuator (not shown) that drives the flap 5c in order to control the opening (VGT opening) of the flap 5c in the turbine 5b of the turbocharger 5. S130 is output. Further, the control device 60 outputs a control signal S131 to an actuator (not shown) that drives the intake shutter valve 7 in order to control the opening degree of the intake shutter valve 7. Further, the control device 60 outputs a control signal S132 to the glow plug 21 in order to control the voltage and / or current applied to the glow plug 21. Further, the control device 60 outputs a control signal S133 to the fuel injection valve 20 in order to control the fuel injection amount and fuel injection timing of the engine E. In the present embodiment, the control device 60 controls the fuel injection valve 20 so as to perform at least two pre-injections before the main injection (main injection). The pre-injection is a fuel injection for creating a fire type in advance in the combustion chamber 17 of the engine E in order to reduce NOx and improve combustion noise. Main injection is fuel injection for generating engine torque to be output, and fuel injection for actively controlling engine torque.

  In addition, the control device 60 outputs control signals S134, S135, S136, and S137 to control the alternator 26, the fuel warmer 32, the fuel pressure regulator 34, and the common rail pressure reducing valve 36, respectively. Further, the control device 60 outputs a control signal S138 to an actuator (not shown) that drives the high pressure EGR valve 43b in order to control the opening degree of the high pressure EGR valve 43b. Further, the control device 60 outputs a control signal S139 to an actuator (not shown) that drives the low pressure EGR valve 48c in order to control the opening degree of the low pressure EGR valve 48c. Further, the control device 60 outputs a control signal S140 to an actuator (not shown) that drives the exhaust shutter valve 49 in order to control the opening degree of the exhaust shutter valve 49.

  In addition, the control device 60 supplies control signals S141 and S142 to each of the rear differential 141 and the headlight 142 as auxiliary machines in the vehicle. Further, the control device 60 outputs a control signal S154 to the air conditioner condenser fan 154 to control the operation of the air conditioner condenser fan 154 for cooling the refrigerant passing through the condenser of the air conditioner. Further, the control device 60 outputs a control signal S159 to the air conditioner compressor clutch 159 so as to switch connection / disconnection of the air conditioner compressor clutch 159 provided in the compressor that compresses the refrigerant of the air conditioner.

  The control device 60 includes a CPU, various programs that are interpreted and executed on the CPU (including basic control programs such as an OS and application programs that are activated on the OS to realize specific functions), programs, and various types of programs. It is constituted by a computer having an internal memory such as a ROM or RAM for storing data.

<Deposit deposit>
In the present embodiment, the control device 60 performs deposit burnout control in which when the deposit is accumulated in the combustion chamber 17 (particularly, the fuel injection valve 20), the temperature of the combustion chamber 17 is raised to burn out the deposited deposit. Hereinafter, the deposit burnout control for the purpose of burning the deposit accumulated on the fuel injection valve 20 will be described.

FIG. 3 is an enlarged cross-sectional view of the fuel injection valve 20 according to the present embodiment. As shown in FIG. 3, the fuel injection valve 20 includes a substantially cylindrical main body 20a, a needle valve 20b that can move in the axial direction inside the main body 20a, and a circumferentially equal interval on the tip side of the main body 20a. And a plurality of nozzle holes 20c formed on the surface. On the outer surface of the main body 20a, a substantially cylindrical recess 20d having a diameter larger than that of the nozzle hole 20c is formed at a position corresponding to the nozzle hole 20c.
The fuel injection valve 20 is arranged so that the tip end side thereof protrudes into the combustion chamber 17 of the engine E, so that the injection hole 20 c opens into the combustion chamber 17.

In the fuel injection valve 20 having such a structure, when the needle valve 20b moves in the axial direction, a gap is formed between the main body 20a and the needle valve 20b, and fuel passing through the gap burns from the nozzle hole 20c. It is injected into the chamber 17.
Here, a recess 20d is formed around the injection hole 20c, and a small amount of the injected fuel adheres in the recess 20d. The fuel adhering in this way does not easily mix with the air in the combustion chamber 17 and does not burn well, and remains in the recess 20d as a deposit.

When the operation is performed at a high load, the temperature in the combustion chamber 17 becomes high, and most of the generated deposit is burned out. However, in operation with a low load, the temperature in the combustion chamber 17 is not so high. For this reason, when the operation at a low load is repeated, the deposit does not burn out and tends to accumulate in the recess 20d. In particular, since the recess 20d of the fuel injection valve 20 is recessed from the outer surface of the main body 20a of the fuel injection valve 20, it is far from the combustion gas, and the surface area of the recess 20d is relatively large. It is easy to become. Moreover, since the nozzle hole 20c is cooled by the heat of vaporization of the fuel when the fuel is injected from the nozzle hole 20c, the space in the recess 20d is also likely to become low temperature. For this reason, the deposit in the recess 20d is easily deposited without being burned out.
If deposits accumulate in the recess 20d of the fuel injection valve 20 in this way, good fuel injection from the injection hole 20c is hindered, and homogeneous combustion in the combustion chamber 17 is not performed, causing problems such as deterioration in fuel consumption. Occur.

In the present embodiment, focusing on the deposit accumulated in the recess 20d of the fuel injection valve 20, the control device determines that the deposit has accumulated in the recess 20d for the purpose of burning the deposit accumulated in this portion. 60 performs deposit burning control for burning the deposit.
In order to burn off the deposit accumulated in the recess 20d, the surface temperature of the fuel injection valve 20 requires a temperature of, for example, 250 ° C. or higher. As described above, the concave portion 20d of the fuel injection valve 20 is a portion in which the temperature does not easily rise in the combustion chamber 17, and therefore, in order to make the surface temperature of the fuel injection valve 20 higher than such a temperature, The maximum temperature (in other words, the maximum temperature of the combustion gas, which corresponds to the in-cylinder temperature at the compression top dead center) needs to be much higher than usual, for example, 1500 K (or 1227 ° C.) or higher. Therefore, in this embodiment, the required in-cylinder temperature for deposit burnout control is set to 1500 K (or 1227 ° C.) or higher.

<Advance control of fuel injection timing>
In order to burn out the deposit in the recess 20d of the fuel injection valve 20, in the present embodiment, the control device 60 performs the fuel injection timing rather than during normal operation (when the deposit burnout control is not performed. The same applies hereinafter). By advancing (fuel injection start timing), the combustion gravity center position is advanced, the in-cylinder maximum temperature is increased, and the surface temperature of the fuel injection valve 20 necessary for deposit burnout is increased to a predetermined value or more. Specifically, the control device 60 determines the first crank angle of the engine cycle at the fuel injection timing of the fuel injection valve 20 when the vehicle is traveling at a certain rotation speed and required torque of the engine E during normal operation. When the crank angle is used, during the deposit burnout control, the second crank angle (at least in compression) is advanced from the first crank angle at the same rotational speed and required torque as in the normal operation. The fuel injection is started at the crank angle before the dead center).

  In the present embodiment, fuel injection is performed in three stages (two pre-injections and then main injection), and the fuel injection that starts at the second crank angle is a main injection that mainly contributes to the start of combustion. Point to. Therefore, the second crank angle is set as a crank angle at a position where the main injection is started and advanced by a predetermined advance amount ΔT (defined by the rotation angle of the crankshaft 25) from the compression top dead center. Is done.

(1) Setting of minimum required advance amount The minimum value ΔT _min of the advance amount ΔT with respect to the compression top dead center of the second crank angle, that is, the minimum required advance amount is set as follows.

  Basically, the higher the fuel injection timing of the main injection is earlier than the compression top dead center (TDC), the higher the maximum temperature of the combustion gas. The advance amount ΔT is set to a fuel injection timing that can realize a combustion start timing at which the maximum temperature of the combustion gas is equal to or higher than the required in-cylinder temperature (1500 K (or 1227 ° C. in this embodiment)).

  Further, the maximum temperature of the combustion gas changes according to the geometric compression ratio of the engine E. When the geometric compression ratio of the engine E becomes low, the maximum temperature of the combustion gas becomes low. Here, in this embodiment, a low compression ratio diesel engine having a geometric compression ratio of about 14 is employed. For this reason, even if fuel is injected in the compression stroke and combustion is started, the degree of compression of the gas up to the compression top dead center is reduced as compared with an engine with a high compression ratio. Temperature does not rise easily. Therefore, in order to achieve the required in-cylinder temperature, it is necessary to increase the advance amount ΔT and set the fuel injection timing earlier than when the geometric compression ratio is relatively high. Thus, by relatively advancing the fuel injection timing, the temperature increase period due to compression after combustion becomes longer, and the maximum temperature of the combustion gas in the cylinder increases. Therefore, from this viewpoint, the advance amount ΔT is set to be larger as the geometric compression ratio is lower.

  As described above, the advance amount ΔT changes in accordance with the geometric compression ratio of the engine E. From the above viewpoint, the present inventor has a relationship between the geometric compression ratio and the advance amount ΔT. And the following formula was found.

ΔT ≧ a ₁ × CR + b ₁

Here, ΔT is the advance amount from the compression top dead center, and CR is the geometric compression ratio of the engine E. Further, a ₁ and b ₁ are constants, and a ₁ <0.

In the above functions, a ₁ and b ₁ are constants determined according to the operating condition of the engine E. In this embodiment, the operating conditions at the time of deposit burnout control are as follows: engine E rotation speed 1750 rpm, supercharging pressure 130 kPa, engine water temperature 82 ° C., fuel injection pressure 70 MPa, intake air temperature 25 ° C., load (average The effective pressure is set to be 300 kPa. Under this condition, a ₁ and b ₁ are a ₁ = −3.56 and b ₁ = 88.7, respectively. It should be noted that the specific values of a ₁ and b ₁ are the engine values in the case where control is performed such as reduction of the EGR gas amount described later, increase in supercharging pressure, increase in engine resistance due to energization of the glow plug 21, etc. It is a numerical value calculated under the condition of E.
In the present embodiment, using such a function, the range of the advance amount ΔT is obtained according to the geometric compression ratio, and the minimum value ΔT _min of the advance amount ΔT is determined.

(2) Setting of Maximum Required Advance Amount The maximum value ΔT _max of the advance amount ΔT with respect to the compression top dead center of the second crank angle, that is, the maximum required advance amount is set as follows.

  Basically, the earlier the fuel injection timing of main injection is from the compression top dead center (TDC), the lower the temperature of the injected fuel. The advance amount ΔT is set at a fuel injection timing such that the temperature of the injected fuel reaches a predetermined ignition possible temperature.

Further, the temperature of the injected fuel changes according to the geometric compression ratio of the engine E, and when the geometric compression ratio of the engine E becomes low, the temperature of the injected fuel becomes low. Here, in this embodiment, a low compression ratio diesel engine having a geometric compression ratio of about 14 is employed. For this reason, if the advance amount ΔT is too large, when the fuel is injected, the fuel does not reach the ignition temperature and combustion is not started at a desired timing, or the combustion becomes incomplete, and the maximum in-cylinder temperature is reached. May become insufficient. Therefore, in this embodiment, it is necessary to set the advance angle amount ΔT to be smaller and the fuel temperature at the fuel injection timing to be higher than when the geometric compression ratio is relatively high.
Therefore, from this point of view, the advance amount ΔT is set smaller as the geometric compression ratio is lower.

  As described above, the advance amount ΔT changes in accordance with the geometric compression ratio of the engine E. From the above viewpoint, the present inventor has a relationship between the geometric compression ratio and the advance amount ΔT. And the following formula was found.

ΔT ≦ a ₂ × CR + b ₂

Here, ΔT is the advance amount from the compression top dead center, and CR is the geometric compression ratio of the engine E. A ₂ and b ₂ are constants, and a ₂ > 0.

Among the above functions, a ₂ and b ₂ are constants determined according to the operating condition of the engine E. In the present embodiment, as described above, the operating conditions at the time of deposit burnout control are as follows: engine E rotation speed is 1750 rpm, supercharging pressure is 130 kPa, engine water temperature is 82 ° C., fuel injection pressure is 70 MPa, and intake air temperature is 25 The temperature (degree C) and the load (average effective pressure) are set to 300 kPa. Under this condition, a ₂ and b ₂ are a ₂ = 4.2 and b ₂ = −47, respectively. It should be noted that the specific values of a ₂ and b ₂ are engine E values when control is performed such as reduction of the EGR amount described later, increase of supercharging pressure, increase of engine resistance due to energization of the glow plug 21, and the like. It is a numerical value calculated under the conditions of
In the present embodiment, using such a function, the range of the advance amount ΔT is obtained according to the geometric compression ratio, and the maximum value ΔT _max of the advance amount ΔT is determined.

With the setting method as described above, the minimum value ΔT _min and the maximum value ΔT _max of the advance amount ΔT are determined, and the advance amount ΔT is determined within the range of ΔT _min ≦ ΔT ≦ ΔT _max .
In this embodiment, ΔT is set to 40 °, and therefore the second crank angle is 40 ° before compression top dead center. In the present embodiment, the control device 60 performs two pre-injections by the fuel injection valve 20 at 56 ° before compression top dead center and 48 ° before compression top dead center, and performs main injection at 40 ° before compression top dead center. At the second crank angle, combustion is started at a position 25 ° before compression top dead center.

<Control of EGR gas amount during deposit burnout control>
In the present embodiment, when the fuel injection timing is advanced as described above, the control device 60 performs control to reduce the EGR gas amount from that during normal operation, thereby increasing the in-cylinder oxygen concentration, Increase the maximum temperature effectively. In particular, in the present embodiment, the control device 60 controls both the high-pressure EGR valve 43b of the high-pressure EGR device 43 and the low-pressure EGR valve 48c of the low-pressure EGR device 48 to be fully closed during the deposit burnout control, and enters the intake system IN. The introduction of EGR gas is cut off.

When the amount of EGR gas is reduced as described above, the intake pressure becomes relatively high, the resistance is increased in the intake stroke in which the piston 23 is lowered, and the pump loss is increased. Therefore, the amount of fuel injection necessary to maintain the desired engine speed increases (basically, the diesel engine does not adjust the intake air amount with the throttle valve like the gasoline engine, so the desired engine The fuel injection amount is adjusted to achieve the rotational speed). As a result, by burning a relatively large amount of fuel, the in-cylinder gas temperature rises, and the deposit accumulated on the fuel injection valve 20 can be effectively burned out.
The method for setting the engine speed applied during deposit burnout control will be described in detail in a later section.

<Glow plug control during deposit burnout control>
In the present embodiment, the control device 60 is configured to increase the energization amount of the glow plug 21 (meaning energization current or energization voltage; hereinafter the same applies) during deposit burnout control as compared to during normal operation. Yes. Specifically, the control device 60 determines the energization amount to the glow plug 21 at the time of deposit burnout control when the energization amount to the glow plug 21 at a certain rotation speed and required torque during normal operation is set as the first energization amount. The second energization amount is controlled to be higher than the first energization amount.

  As described above, if the advance amount ΔT with respect to the compression top dead center of the second crank angle is excessively increased, when the fuel is injected, the fuel does not reach the ignition temperature and combustion is not started at a desired timing. Or combustion may become incomplete and there exists a possibility that the in-cylinder maximum temperature may become inadequate. Therefore, it is preferable to improve the ignition environment by increasing the energization amount of the glow plug 21 so that the in-cylinder temperature reaches the fuel ignition temperature at a desired time.

  Therefore, in the present embodiment, the higher in-cylinder maximum temperature in the combustion chamber 17 is realized by increasing the energization amount to the glow plug 21 to increase the in-cylinder temperature and advance the combustion start timing of the fuel. To do. Specifically, in the present embodiment, during normal operation, the glow plug 21 is energized only at the time of warm-up at the start of operation of the engine E. Therefore, the rotational speed and required torque of the engine E during deposit burnout control At the same rotation speed and required torque, the glow plug 21 is not energized during normal operation. Therefore, basically, the first energization amount of the glow plug 21 applied during normal operation is zero. On the other hand, during the deposit burnout control, the second energization amount is controlled so that the glow plug 21 reaches a target temperature (for example, 1200 ° C.).

  Since the glow plug 21 uses the electric power generated by the alternator 26, if the energization amount of the glow plug 21 is increased during the deposit burnout control as described above, the required power generation amount at the alternator 26 is increased and applied to the engine E. Resistance (load) to be increased. As a result, the amount of fuel injection required to maintain the desired engine speed increases. As a result, by burning a relatively large amount of fuel, the in-cylinder gas temperature rises, and the deposit accumulated on the fuel injection valve 20 can be effectively burned out.

<Control of supercharging pressure during deposit burnout control>
In the present embodiment, the control device 60 performs control to increase the supercharging pressure by the turbocharger 5 more than during normal operation during deposit burnout control. In this way, the in-cylinder pressure is increased to improve the ignition environment in the combustion chamber 17, and the deterioration of fuel ignitability and incomplete combustion due to the advance of the fuel injection timing as described above are suppressed. To do. Further, when the boost pressure is increased in this way, the resistance applied to the engine E, particularly the resistance applied to the piston 23 (hereinafter referred to as “piston resistance” as appropriate) increases, so that the desired engine rotation speed is increased. The amount of fuel injection required to maintain the number will increase. As a result, by burning a relatively large amount of fuel, the in-cylinder gas temperature rises, and the deposit accumulated on the fuel injection valve 20 can be effectively burned out.

<Control of auxiliary machine drive resistance during deposit burnout control>
In the present embodiment, the control device 60 performs control to increase the resistance (auxiliary drive resistance) applied to the engine E to drive the auxiliary equipment in the vehicle during deposit burnout control, and performs desired engine rotation. The amount of fuel injection required to maintain the number is increased. The auxiliary machine is, for example, a headlight 142, a rear differential switch 94, or an air conditioner. Since the resistance (load) applied to the engine E increases even when the glow plug 21 is energized as described above, the glow plug 21 may be included in the auxiliary equipment here.

  When such an auxiliary device is driven, for example, when the glow plug 21, the headlight 142, the rear differential 141, or the like is operated, the power of the battery that charges the generated power of the alternator 26 is consumed. As a result, in order to increase the power generation amount of the alternator 26, the amount of work of the engine E for generating the alternator 26 (that is, auxiliary machine drive resistance) increases, and the fuel required to maintain the desired engine speed. The injection amount will increase.

<Control of air-conditioner condenser fan during deposit burnout control>
In the present embodiment, the control device 60 performs control to weaken the output of the air conditioner condenser fan 154 during the deposit burnout control so as to increase the refrigerant pressure (refrigerant temperature) on the upstream side of the compressor of the air conditioner. . By doing so, the work of the compressor of the air conditioner connected to the output shaft of the engine E is increased, and the resistance applied to the engine E is increased, so that it is necessary to maintain the desired engine speed. Increase the fuel injection amount. The “output of the air conditioner condenser fan 154” is typically defined by the air volume and the wind pressure by the condenser fan 154.

<Engine speed during deposit burnout control>
In the present embodiment, the control device 60 burns away the deposit accumulated on the fuel injection valve 20 and the relationship between the engine speed and the advanceable ignition timing limit on the advance side, based on the operating state of the engine E. The minimum engine speed and the maximum engine speed at which the ignition timing limit satisfies the required ignition timing are set (hereinafter referred to as “lower limit speed” and “upper limit speed” as appropriate). The engine speed between the lower limit speed and the upper limit speed is applied at the time of deposit burnout control. In particular, in the present embodiment, the control device 60 issues permission to execute the deposit burnout control only when the current engine speed is not less than the lower limit speed and not more than the upper limit speed.

  With reference to FIG. 4, the lower limit rotation speed and the upper limit rotation speed applied in the embodiment of the present invention will be specifically described. In FIG. 4, the horizontal axis indicates the engine speed, and the vertical axis indicates the ignition timing limit that can be achieved on the advance side. The graph G11 shows the relationship between the engine speed and the ignition timing limit when the supercharging pressure by the turbocharger 5 is low (for example, when the VGT opening degree of the turbocharger 5 is set to the open side opening degree). The graph G12 shows the relationship between the engine speed and the ignition timing limit when the supercharging pressure by the turbocharger 5 is high (for example, when the VGT opening of the turbocharger 5 is set to the open side). Showing the relationship. These graphs G11 and G12 are set by the control device 60 based on the performance of the engine E such as the performance of the turbocharger 5 and the magnitude of the auxiliary machine drive resistance. Reference symbol R1 indicates an ignition timing (required ignition timing) that should be applied to burn out deposits deposited on the fuel injection valve 20. The required ignition timing R1 is set by the control device 60 based on, for example, the deposit accumulation amount of the fuel injection valve 20, the oil temperature / water temperature, the magnitude of the auxiliary drive resistance, and the like.

  As shown in graphs G11 and G12, in the relatively low engine speed range, the ignition timing limit becomes retarded as the engine speed decreases (particularly, in the region where the engine speed is considerably low, the ignition timing limit). Is behind the required ignition timing R1). This is because, when the engine speed is low, the supercharging pressure cannot be almost increased, and the ignition environment in the combustion chamber 17 cannot be improved, so that ignition cannot be performed at the position on the advance side.

  In the relatively high engine speed range, the ignition timing limit becomes more retarded as the engine speed increases (particularly, in the area where the engine speed is considerably high, the ignition timing limit is higher than the required ignition timing R1). On the retard side). This is because the crank angular speed increases as the engine speed increases, so the fuel ignition timing is higher when the engine speed is higher than when the engine speed is low (the same combustion injection timing is applied). This is because the crank angle corresponding to is approaching the compression top dead center, that is, it is retarded. As the engine speed increases, the supercharging pressure can be increased and the ignition environment in the combustion chamber 17 can be improved. However, the ignition timing retarded due to the increased crank angular velocity as described above. Because the influence is great, the ignition timing limit is retarded.

  Further, comparing the graph G11 and the graph G12, when the supercharging pressure by the turbocharger 5 becomes high, the ignition timing limit is shifted to the advance side as a whole. This is because, as described above, when the supercharging pressure is increased, the ignition environment in the combustion chamber 17 is improved.

  In the present embodiment, the control device 60 sets the lower limit speed and the upper limit speed based on the relationship between the engine speed and the ignition timing limit as shown in the graphs G11 and G12 and the required ignition timing R1. Specifically, when the supercharging pressure by the turbocharger 5 is low (graph G11), the control device 60 determines the minimum engine speed (the ignition timing limit is more advanced than the required ignition timing R1) ( The rotation speed indicated by reference numeral N11 is set as the lower limit rotation speed), and the rotation speed indicated by reference numeral N12 is set as the maximum engine rotation speed (upper limit rotation speed) at which the ignition timing limit is on the more advanced side than the required ignition timing R1. . The range defined by the lower limit rotational speed N11 and the upper limit rotational speed N12 is an engine rotational speed range in which execution of deposit burnout control is permitted.

  In addition, when the supercharging pressure by the turbocharger 5 is high (graph G12), the control device 60 sets the minimum engine speed (lower limit speed) at which the ignition timing limit is advanced from the required ignition timing R1. ) As the maximum engine speed (upper limit speed) at which the ignition timing limit is on the more advanced side than the required ignition timing R1. When the supercharging pressure is high, the lower limit rotational speed is lower and the upper limit rotational speed is higher than when the supercharging pressure is low. That is, when the supercharging pressure is high, the range of engine speeds in which the execution of deposit burnout control is permitted is wider than when the supercharging pressure is low.

  Here, in the present embodiment, the control device 60 further sets the upper limit rotational speed in consideration of terminating the combustion period after the ignition of fuel before the compression top dead center. . This will be specifically described with reference to FIG.

  In FIG. 5, the crank angle is shown in the horizontal direction, the graph G21 shows the heat generation rate due to combustion in the combustion chamber 17 when the engine speed is relatively low, and the graph G22 shows a comparison of the engine speed. The heat generation rate due to combustion in the combustion chamber 17 in the case where the temperature is high is shown. As shown in the graphs G21 and G22, when the engine speed increases, the crank angular speed increases, so the crank angle period (combustion period expressed by crank angle) from the start of combustion to the end of combustion increases. As a result, when the engine speed increases, the combustion period may exceed the compression top dead center (TDC) as shown in the graph G22. As described above, when the combustion period exceeds the compression top dead center, that is, when the combustion period extends beyond the compression top dead center, the amount of heat input to the combustion injection valve 20 decreases, and the combustion injection valve 20 The deposited deposit cannot be burned out properly.

  Therefore, in the present embodiment, the control device 60 sets the upper limit rotational speed based on the maximum engine speed that can complete the combustion period before the compression top dead center. In one example, the control device 60 sets the maximum engine speed that can complete the combustion period before the compression top dead center as the upper limit engine speed. In another example, the control device 60 has a maximum engine speed at which an ignition timing limit that satisfies the required ignition timing R1 as described above can be obtained, and a maximum that can complete the combustion period before compression top dead center. Of the engine speeds, the smaller engine speed is set as the upper limit speed.

  Next, an example of a time chart when deposit sintering control according to the embodiment of the present invention is performed will be described with reference to FIG. FIG. 6 shows, in order from the top, changes in engine speed over time, changes in fuel injection timing, and deposit amounts deposited on the fuel injection valve 20 (particularly deposit amounts deposited in the recesses 20d of the injection holes 20c).

  As shown in FIG. 6, at the time t1, the actual engine speed falls within the range A1 defined by the above-described lower limit speed and upper limit speed. Therefore, control device 60 starts deposit burnout control at time t11. Specifically, the control device 60 performs control to advance the fuel injection timing of the fuel injection valve 20. The control device 60 controls the EGR gas amount, the glow plug 21, the supercharging pressure, the auxiliary driving resistance, and the air conditioner condenser fan 154 as described in the above section. (Not shown). As a result, the combustion gas temperature rises greatly, and the surface temperature of the fuel injection valve 20 rises greatly, so that the deposit accumulated in the recess 20d of the injection hole 20c of the fuel injection valve 20 is effectively burned out. .

  In the above description, the lower limit rotation speed and the upper limit rotation speed are set according to the supercharging pressure, but when the lower limit rotation speed and the upper limit rotation speed are further set according to the fuel injection amount of the fuel injection valve 20. Good. Specifically, the control device 60 sets the lower limit rotational speed to a higher rotational speed as the fuel injection amount increases. This is because the higher the fuel injection amount, the higher the engine speed and the higher the supercharging pressure in order to improve the ignition environment. Further, the control device 60 sets the upper limit rotational speed to a lower rotational speed as the fuel injection amount is larger. This is because the greater the fuel injection amount, the longer the combustion period, and the lower the maximum engine speed that the combustion period is completed before compression top dead center.

  Furthermore, the control device 60 sets the lower limit rotational speed to a lower rotational speed as the accessory driving resistance is higher. This is because when the accessory driving resistance is high, the fuel injection amount to be applied at the same engine speed can be increased and the in-cylinder gas temperature can be appropriately increased as compared with the case where the accessory driving resistance is low. Because it can. Further, the control device 60 sets the upper limit rotational speed to a higher rotational speed as the fuel injection pressure from the fuel injection valve 20 is higher. This is because when the injection pressure is high, the vaporization of the fuel in the combustion chamber 17 progresses, the flame propagation becomes faster, and the combustion period becomes shorter. Therefore, the maximum engine speed that the combustion period is completed before compression top dead center is high. It is because it tends to become.

<Deposit accumulation judgment of fuel injection valve>
When deposit accumulates in the recess 20 d of the injection hole 20 c of the fuel injection valve 20, the fuel injected from the fuel injection valve 20 is not easily diffused into the combustion chamber 17. Therefore, homogeneous combustion is not performed in the combustion chamber 17, PM (typically soot) is likely to be generated, and the rate at which PM is collected in the DPF 46 is increased. As a result, the process for removing the PM collected by the DPF 46 by combustion (corresponding to filter regeneration control, hereinafter referred to as “DPF regeneration”) tends to be executed with high frequency. Therefore, in the present embodiment, the control device 60 determines whether or not deposits are accumulated on the fuel injection valve 20 based on the execution frequency of DPF regeneration. In particular, in the present embodiment, the control device 60 obtains a distance (corresponding to an interval at which DPF regeneration is performed) that the vehicle has traveled since DPF regeneration was performed last time until DPF regeneration is performed this time. By comparing the travel distance and a predetermined determination distance, it is determined whether or not deposits have accumulated on the fuel injection valve 20. For example, the control device 60 determines that deposits are accumulated on the fuel injection valve 20 when the travel distance corresponding to the DPF regeneration execution interval is less than a predetermined determination distance (for example, 50 km).

<Control flow>
Next, a specific flow of control (processing) according to the embodiment of the present invention will be described.

  First, with reference to FIG. 7, the control (main control) mainly performed in the embodiment of the present invention will be described. FIG. 7 is a flowchart showing main control according to the embodiment of the present invention. In this flow, in addition to the control for realizing the target oxygen concentration and the target intake air temperature according to the required injection amount, a deposit for determining whether or not deposits are accumulated on the fuel injection valve 20 Determination processing (deposit accumulation determination processing) is performed. The flow is typically repeatedly executed at a predetermined cycle by the control device 60 after the ignition of the vehicle is turned on.

  First, in step S11, the control device 60 acquires at least one or more of the signals S94 to S122 output from the various sensors 94 to 122 described above.

  Next, in step S <b> 12, the control device 60 sets a target torque to be output from the engine E based on the accelerator opening detected by the accelerator opening sensor 100. In step S13, the control device 60 sets a required injection amount to be injected from the fuel injection valve 20 based on the target torque set in step S12 and the engine speed.

  Next, in step S14, the control device 60 determines the fuel injection pattern, fuel pressure, target oxygen concentration, target intake air temperature, and EGR control based on the required injection amount set in step S13 and the engine speed. A mode (a mode in which both or one of the high pressure EGR device 43 and the low pressure EGR device 48 is operated, or a mode in which neither the high pressure EGR device 43 nor the low pressure EGR device 48 is operated) is set.

  Next, in step S15, the control device 60 sets a state quantity that realizes the target oxygen concentration and the target intake air temperature set in step S14. For example, this state quantity includes the amount of exhaust gas recirculated to the intake system IN by the high pressure EGR device 43 (high pressure EGR gas amount) and the amount of exhaust gas recirculated to the intake system IN by the low pressure EGR device 48 (low pressure EGR gas amount). And a supercharging pressure by the turbocharger 5 is included.

  Next, in step S <b> 16, the control device 60 controls each actuator that drives each component of the engine system 200 based on the state quantity set in step S <b> 15. In this case, the control device 60 sets a limit value or a limit range according to the state quantity, sets a control amount of each actuator such that the state value complies with the limit value or the limit range, and executes control. .

  Further, in parallel with the processes in steps S11 to S16 described above, the control device 60 executes a deposit determination process for determining whether or not deposits are accumulated on the fuel injection valve 20 in step S17.

  Next, the deposit determination process according to the embodiment of the present invention will be specifically described with reference to FIG. FIG. 8 is a flowchart showing deposit determination processing according to the embodiment of the present invention. This flow is executed by the control device 60 in step S17 of FIG.

  First, in step S <b> 21, the control device 60 acquires the DPF differential pressure (the difference in exhaust pressure between the upstream side and the downstream side of the DPF 46) detected by the DPF differential pressure sensor 120.

  Next, in step S22, the control device 60 determines whether or not the DPF differential pressure acquired in step S21 is equal to or higher than a predetermined pressure. In this step S22, the control device 60 determines whether or not the amount of PM trapped in the DPF 46 has become equal to or greater than a predetermined amount based on the DPF differential pressure, that is, whether or not the amount of PM trapped for DPF regeneration has been reached. Judging. Since there is a correlation between the amount of PM collected by the DPF 46 and the DPF differential pressure, the amount of PM collected by the DPF 46 can be determined based on the DPF differential pressure.

  If the result of determination in step S22 is that the DPF differential pressure is less than the predetermined pressure (step S22: No), the process ends. In this case, since the amount of PM collected by the DPF 46 does not exceed a predetermined amount, the control device 60 determines that the DPF regeneration is not in a situation. On the other hand, when the DPF differential pressure is equal to or higher than the predetermined pressure (step S22: Yes), the process proceeds to step S23, where the control device 60 determines that the DPF regeneration should be performed and sets the DPF regeneration execution flag. Set to on and issue a DPF regeneration execution request. In this case, the control device 60 executes control for raising the temperature of the DPF 46 to a temperature at which the PM collected by the DPF 46 can be removed by combustion.

  Next, in step S24, the control device 60 acquires the travel distance when the DPF regeneration execution flag is turned on this time, in other words, the travel distance when the DPF regeneration is performed this time. This travel distance is stored in a predetermined memory or the like. In step S25, the control device 60 obtains the distance traveled when the DPF regeneration execution flag was turned on this time and the distance traveled when the DPF regeneration execution flag was previously turned on, acquired in step S24. Calculate the difference. That is, the control device 60 calculates the distance traveled by the vehicle from the previous execution of DPF regeneration to the current execution of DPF regeneration. Hereinafter, the distance is appropriately referred to as “calculated travel distance”.

  Next, in step S26, the control device 60 determines whether or not the calculated travel distance obtained in step S25 is less than 50 km. As a result of the determination, if the calculated travel distance is less than 50 km (step S26: Yes), the process proceeds to step S27, and the control device 60 increments a predetermined counter (50 km counter) by 1. In step S28, the control device 60 determines whether or not the 50 km counter is 3 or more. As a result of the determination, if the 50 km counter is 3 or more (step S28: Yes), the process proceeds to step S35. In this case, since the DPF regeneration has been executed at a relatively high frequency, the control device 60 determines that the deposit has accumulated on the fuel injection valve 20, and turns on the deposit burnout flag for burning this deposit. (Step S35). Then, the process proceeds to step S <b> 36, and the control device 60 turns on a warning lamp indicating that deposits are accumulated on the fuel injection valve 20.

  On the other hand, when the calculated travel distance obtained in step S25 is 50 km or more (step S26: No), the process proceeds to step S29, and the control device 60 determines whether the calculated travel distance is less than 70 km. As a result of the determination, if the calculated travel distance is less than 70 km (step S29: Yes), the process proceeds to step S30, and the control device 60 increments a predetermined counter (70 km counter) by one. Then, the process proceeds to step S31, and the control device 60 determines whether or not the 70 km counter is 20 or more. As a result of the determination, when the 70 km counter is 20 or more (step S31: Yes), the process proceeds to step S35. Also in this case, since the DPF regeneration is executed at a relatively high frequency, the control device 60 determines that the deposit is accumulated on the fuel injection valve 20, and sets the deposit burnout flag to ON (step S35). . Then, the process proceeds to step S <b> 36, and the control device 60 turns on a warning lamp indicating that deposits are accumulated on the fuel injection valve 20.

  On the other hand, when the calculated travel distance obtained in step S25 is 70 km or more (step S29: No), the process proceeds to step S32, and the control device 60 determines whether the calculated travel distance is less than 100 km. As a result of the determination, if the calculated travel distance is less than 100 km (step S32: Yes), the process proceeds to step S33, and the control device 60 increments a predetermined counter (100 km counter) by one. Then, the process proceeds to step S34, and the control device 60 determines whether or not the 100 km counter is 50 or more. As a result of the determination, if the 100 km counter is 50 or more (step S34: Yes), the process proceeds to step S35. Also in this case, since the DPF regeneration is executed at a relatively high frequency, the control device 60 determines that the deposit is accumulated on the fuel injection valve 20, and sets the deposit burnout flag to ON (step S35). . Then, the process proceeds to step S <b> 36, and the control device 60 turns on a warning lamp indicating that deposits are accumulated on the fuel injection valve 20.

  On the other hand, when the calculated travel distance obtained in step S25 is 100 km or more (step S32: No), the process ends. In this case, since the execution interval of DPF regeneration is long, the control device 60 determines that no deposit is accumulated on the fuel injection valve 20.

  When the 50 km counter is less than 3 (step S28: No), the 70 km counter is less than 20 (step S31: No), and the 100 km counter is less than 50 (step S34: No). In either case, the process ends. Also in this case, the control device 60 determines that no deposit is accumulated on the fuel injection valve 20. In the situation where the process proceeds to step S28, step S31 and step S34, since the execution interval of DPF regeneration is relatively short, there is a possibility that deposits are accumulated on the fuel injection valve 20, but deposits on the fuel injection valve 20 are accumulated. There is a possibility that an execution request for DPF regeneration has been issued due to other factors (for example, an operation that frequently switches between depression and depression of the accelerator pedal 95 or an operation that operates the engine E for a long time in a high load range). Conceivable. Therefore, in the case described above, control device 60 does not set the deposit burnout flag to ON. By doing so, erroneous determination of deposit accumulation in the fuel injection valve 20 is prevented.

  Thus, in this embodiment, the travel distance from when DPF regeneration is executed last time until DPF regeneration is executed this time is determined using a plurality of determination distances (50 km, 70 km, and 100 km), and the plurality of these distances are determined. A plurality of counters (a 50 km counter, a 70 km counter, and a 100 km counter) corresponding to the determination distance are defined, and the number of times the DPF regeneration is executed is separately counted. Then, using a plurality of determination values corresponding to the plurality of counters, specifically, a determination value that decreases as the determination distance corresponding to the counter decreases (for a counter for 50 km, for 3, 70 km) 20 is used for the counter and 50 is used for the 100 km counter, and it is determined whether or not deposits are accumulated on the fuel injection valve 20. By doing so, deposit accumulation in the fuel injection valve 20 is accurately determined.

  The 50 km counter, the 70 km counter, and the 100 km counter are each reset after execution of deposit burnout control, which will be described later, that is, set to 0.

  Next, deposit burnout control according to the embodiment of the present invention will be specifically described with reference to FIG. FIG. 9 is a flowchart showing deposit burnout control according to the embodiment of the present invention. This flow is executed by the control device 60 when the vehicle is stored in the dealer and maintenance is performed (assuming that the vehicle is in a non-traveling state). Prior to starting the flow, the control device 60 acquires various types of information on the vehicle in advance.

  First, in step S41, control device 60 determines whether or not a predetermined operation for starting deposit burnout control has been performed by a mechanic or the like. As a result of this determination, when the predetermined operation is performed (step S41: Yes), the process proceeds to step S42, and when the predetermined operation is not performed (step S41: No), the process ends.

  Next, in step S42, control device 60 determines whether or not the deposit burnout flag is on. This deposit burnout flag is set in the deposit determination process of FIG. As a result of the determination in step S42, if the deposit burnout flag is on (step S42: Yes), the process proceeds to step S43. If the deposit burnout flag is not on (step S42: No), the process ends.

  Next, in step S43, control device 60 determines whether or not the gear position of the transmission is set to neutral. As a result of this determination, if the gear stage is set to neutral (step S43: Yes), the process proceeds to step S44. If the gear stage is not set to neutral (step S43: No), the process ends. . In the present embodiment, from the viewpoint of ensuring safety, the deposit burnout control is performed in a state where the output of the engine E is not transmitted to the wheels.

  Next, in step S44, the control device 60 determines that the water temperature (cooling water temperature) and the oil temperature are equal to or higher than a predetermined temperature (for example, 80 to 90 ° C.) based on the outputs of the cooling water temperature sensor 109 and the hydraulic pressure / oil temperature sensor 111. It is determined whether or not there is. As a result of the determination, when the water temperature and the oil temperature are equal to or higher than the predetermined temperature (step S44: Yes), the process proceeds to step S45, and when the water temperature and the oil temperature are lower than the predetermined temperature (step S44: No), the process is performed. finish. In the present embodiment, the deposit burnout control is performed in a state where the engine E is heated up to a temperature at which the deposit of the fuel injection valve 20 can be burned out efficiently.

  Next, in step S45, the control device 60 determines whether or not the headlight switch 95 is on. As a result of this determination, if the headlight switch 95 is on (step S45: Yes), the process proceeds to step S46, and if the headlight switch 95 is off (step S45: No), the process ends. In the present embodiment, the auxiliary drive resistance applied to the engine E is increased by the power consumption due to the lighting of the headlight 142 as an auxiliary machine (specifically, the power generation of the alternator 26 by the power consumption of the headlight 142). The deposit burnout control is performed when the amount increases and the load of the engine E for generating the alternator 26 increases. From the viewpoint of effectively increasing the auxiliary machine driving resistance by the headlight 142, it is preferable to set the headlight 142 to a high beam (generally, the power consumption of the headlight 142 tends to increase when the high light beam is set). .

  Next, in step S46, the control device 60 determines whether or not the air conditioner switch 96 is on. As a result of this determination, if the air conditioner switch 96 is on (step S46: Yes), the process proceeds to step S47. If the air conditioner switch 96 is off (step S46: No), the process ends. In the present embodiment, the load applied to the engine E to operate the air conditioner is high (specifically, the compressor of the air conditioner is operated by the engine E, and therefore the load of the engine E is reduced during the operation of the air conditioner. In this case, deposit burnout control is performed.

  Next, in step S47, since the air conditioner switch 96 is turned on, the control device 60 connects the air conditioner compressor clutch 159 provided in the compressor of the air conditioner. In this way, the output of the engine E is transmitted to the compressor of the air conditioner. Then, the process proceeds to step S48.

  Next, in step S48, the control device 60 determines whether or not the rear differential switch 94 is on. If the result of this determination is that the rear differential switch 94 is on (step S48: Yes), the process proceeds to step S49. If the rear differential switch 94 is off (step S48: No), the process ends. In the present embodiment, a state in which the auxiliary drive resistance applied to the engine E is high due to power consumption by energizing the rear differential 141 as an auxiliary machine (specifically, the power generation amount of the alternator 26 by the power consumption of the rear differential 141). And the load on the engine E for generating power from the alternator 26 is increased).

  Next, in step S49, the control device 60 determines whether or not the air volume of the air conditioner (that is, the output of the blower fan) is maximum based on the output of the air volume switching switch 97 of the air conditioner. As a result of this determination, if the air volume of the air conditioner is the maximum (step S49: Yes), the process proceeds to step S50. If the air volume of the air conditioner is not the maximum (step S49: No), the process ends. In the present embodiment, in order to increase the auxiliary machine drive resistance, the air volume of the air conditioner is maximized (specifically, the power generation amount of the alternator 26 increases due to the power consumption of the blower fan of the air conditioner, and the alternator 26 is caused to generate power. Therefore, the deposit burnout control is performed.

  Next, in step S50, control device 60 sets a lower limit speed and an upper limit speed that define the range of engine speeds to be applied in deposit burnout control based on the operating state of engine E. Specifically, first, the control device 60 determines the relationship between the engine speed and the advanceable ignition timing limit on the advance side based on, for example, the performance of the turbocharger 5 and the magnitude of the auxiliary drive resistance. Further, the required ignition timing to be applied to burn out the deposit accumulated on the fuel injection valve 20 based on, for example, the deposit accumulation amount of the fuel injection valve 20, the oil temperature / water temperature, the magnitude of the auxiliary drive resistance, etc. Ask. Then, the control device 60 sets the minimum engine speed at which the ignition timing limit is advanced from the required ignition timing as the lower limit rotational speed, and the maximum at which the ignition timing limit is advanced from the required ignition timing. Is set as the upper limit. In this case, the control device 60 sets the upper rotational speed in consideration of the maximum engine rotational speed that can complete the combustion period before the compression top dead center.

Next, in step S51, the control device 60 determines whether or not the current engine speed is not less than the lower limit speed and not more than the upper limit speed. That is, control device 60 determines whether or not the current engine speed is within the range of engine speed as an execution condition for deposit burnout control. As a result of this determination, when the current engine speed is not less than the lower limit speed and not more than the upper limit speed (step S51: Yes), the process proceeds to step S52, and the current engine speed is less than the lower limit speed. If it is higher than the upper limit rotational speed (step S51: No), the process ends.
Actually, when a mechanic or the like performs deposit burnout control at the time of vehicle maintenance, the engine speed should be within the range of the engine speed defined by the lower limit speed and the upper limit speed. Do the accelerator operation.

When all the conditions of steps S41 to S46, S48, S49, and S51 described above are satisfied, the control device 60 performs control for burning out deposits deposited on the fuel injection valve 20 in step S52 and subsequent steps. First, in step S <b> 52, the control device 60 performs control for energizing the glow plug 21, that is, performs control for applying current / voltage to the glow plug 21. By doing so, deterioration of fuel ignitability and incomplete combustion due to the advance of the fuel injection timing are suppressed. In addition, by increasing the resistance imparted to the engine E by the power consumption of the glow plug 21 (specifically, the power generation amount of the alternator 26 is increased by energization of the glow plug 21 and the load on the engine E is increased). The in-cylinder gas temperature is raised by increasing the fuel injection amount necessary to maintain the rotational speed.
Specifically, in step S52, the control device 60 sets a substantially upper limit temperature within a range in which the reliability of the glow plug 21 is appropriately secured as a target temperature (for example, 1200 ° C.), and the glow plug 21 sets the target temperature. Energization control is performed so that In this case, the control device 60 estimates the temperature of the glow plug 21 using a predetermined model based on the water temperature, the intake air temperature, the intake air amount, the engine speed, the fuel injection amount, and the like, and compares the estimated temperature with the target temperature. However, energization control is performed so that the glow plug 21 is maintained at the target temperature. By doing so, failure of the glow plug 21 due to the temperature of the glow plug 21 exceeding the target temperature relatively greatly is suppressed.

Next, in step S53, the control device 60 performs control to weaken the output of the air conditioner condenser fan 154 as compared with that during normal operation so as to increase the refrigerant pressure (refrigerant temperature) on the compressor upstream side of the air conditioner. For example, the control device 60 performs control to reduce the duty for driving the air conditioner condenser fan 154. By doing this, the work amount of the compressor of the air conditioner connected to the engine E (the work amount for compressing the refrigerant) is increased, and the resistance given to the engine E is increased, thereby maintaining the target rotational speed. The amount of fuel injection required to do this is increased.
Specifically, in step S53, the control device 60 controls the output of the air conditioner condenser fan 154 based on the outside air temperature so that the refrigerant pressure on the upstream side of the compressor falls within a predetermined range on the high pressure side. In this case, the control device 60 basically lowers the output of the air conditioner condenser fan 154, but increases the output of the air conditioner condenser fan 154 as the outside air temperature increases (that is, as the outside air temperature increases, the air conditioner condenser fan 154 increases). The degree of lowering the output of the fan 154 is reduced). By doing so, it is possible to prevent the compressor of the air conditioner from being stopped due to the refrigerant temperature becoming too high in summer or the like.
In addition, the control device 60 performs the control of the air conditioner condenser fan 154 as described above in a state where the air conditioner is set to heating. This is because if the control is performed with the air conditioner set to cooling in the middle of winter, the evaporator of the air conditioner may be too cold and the air after passing through the evaporator may freeze and the operation of the air conditioner may stop. .

  Next, in step S54, the control device 60 fully closes both the high pressure EGR valve 43b of the high pressure EGR device 43 and the low pressure EGR valve 48c of the low pressure EGR device 48 in order to stop the recirculation of the EGR gas to the intake system IN. Control. By doing so, the oxygen concentration of the gas supplied to the engine E is increased, and the maximum in-cylinder temperature is effectively increased (in other words, the heat generation rate is increased). In addition, the fuel injection amount necessary to maintain the target rotational speed is increased due to an increase in pump loss of the engine E resulting from the reduction in the EGR gas amount.

  Next, in step S55, the control device 60 controls the VGT opening degree (opening degree of the flap 5c) of the turbocharger 5 to the closed side so as to increase the supercharging pressure by the turbocharger 5. In this way, the in-cylinder pressure is increased to improve the ignition environment in the combustion chamber 17, and the deterioration of fuel ignitability and incomplete combustion due to the advance of the fuel injection timing are suppressed. . In addition, the amount of fuel injection required to maintain the target rotational speed is increased by increasing the resistance of the piston 23 due to the increase in the supercharging pressure.

  Next, in step S56, the control device 60 increases the in-cylinder temperature at the compression top dead center (in-cylinder maximum temperature) so as to increase the period during which the combustion gas is compressed in the combustion chamber 17. Advance the fuel injection timing. In this case, the control device 60 advances the fuel injection timing (that is, limits the degree to which the fuel injection timing is advanced) within a range in which the ignitability of the fuel is ensured and incomplete combustion does not occur. Specifically, the control device 60 advances the fuel injection timing in accordance with the geometric compression ratio of the engine E. More specifically, based on the above two expressions indicating the range of the advance amount, the fuel injection timing corresponding to the geometric compression ratio of the target engine E is determined in advance. The fuel injection timing determined as described above is applied.

  Next, in step S57, control device 60 determines whether or not a predetermined time (for example, 120 seconds) has elapsed since the start of deposit burnout control. As a result of this determination, if the predetermined time has elapsed (step S57: Yes), the process proceeds to step S58, where the control device 60 ends the deposit burnout control and sets the deposit burnout flag to OFF. On the other hand, when the predetermined time has not elapsed (step S57: No), the process returns to step S57. In this case, the control device 60 repeats the determination in step S57 until a predetermined time has elapsed.

  In the deposit burnout control described above, the operation condition of the control is that the rear differential switch 94, the air conditioner switch 96, the headlight switch 95, and the air volume switch 97 are manually operated by a mechanic (step S45, (See S46, S48, and S49). In another example, the air volume of the rear differential 141, the air conditioner, the headlight 142, and the air conditioner may be automatically controlled when the deposit burnout control is executed without using a manual operation by such a mechanic as an execution condition. That is, when the deposit burnout control is executed, the rear differential 141, the air conditioner, and the headlight 142 may be automatically turned on, and the airflow of the air conditioner may be automatically maximized.

<Effect>
Next, the operation effect of the diesel engine control method and control system according to the embodiment of the present invention will be described.

  According to the present embodiment, the control device 60 obtains the relationship between the engine speed and the advanceable ignition timing limit on the advance side based on the operating state of the engine E, and the deposit accumulated on the fuel injection valve 20 is calculated. The required ignition timing that should be applied to burn out is calculated, the minimum engine speed at which the ignition timing limit is on the more advanced side than the required ignition timing is set as the lower limit speed, and the current engine speed is the lower limit speed. Only when the number is greater than or equal to the number, permission to execute deposit burnout control is issued. Thereby, the required ignition timing or the ignition timing on the more advanced side than that can be appropriately realized by the control for advancing the fuel injection timing. Therefore, according to this embodiment, it is possible to raise the in-cylinder temperature and appropriately burn out the deposit accumulated on the fuel injection valve 20 (particularly the deposit accumulated on the recess 20d of the injection hole 20c).

  Further, according to the present embodiment, such deposit burnout control is performed when the vehicle is being maintained and when the vehicle is not traveling, so that it is possible to suppress giving a sense of incongruity (noise, etc.) by performing the control during actual vehicle traveling. it can.

  Further, according to the present embodiment, the control device 60 takes into consideration that the ignition environment in the combustion chamber 17 is improved when the supercharging pressure by the turbocharger 5 is high. Set the lower limit speed to a lower speed. Thereby, it is possible to set an appropriate lower limit rotational speed corresponding to the supercharging pressure. In this case, the execution permission range of the deposit burnout control based on the engine speed can be expanded.

  Further, according to the present embodiment, the control device 60 takes into account that if the fuel injection amount is large, it is necessary to increase the engine speed and increase the boost pressure in order to improve the ignition environment. As the fuel injection amount increases, the lower limit rotational speed is set to a higher rotational speed. Thereby, it is possible to set an appropriate lower limit rotational speed according to the fuel injection amount. In this case, according to the fuel injection amount, the execution permission range of the deposit burnout control based on the engine speed can be narrowed, and the required ignition timing or the ignition timing more advanced than that can be appropriately ensured. .

  In addition, according to the present embodiment, the control device 60 takes into account that if the auxiliary machine drive resistance is high, the amount of fuel injection applied at the same engine speed increases and the in-cylinder gas temperature rises. As the machine drive resistance is higher, the lower limit rotational speed is set to a lower rotational speed. Thereby, it is possible to set an appropriate lower limit rotational speed corresponding to the auxiliary machine driving resistance. In this case, the execution permission range of the deposit burnout control based on the engine speed can be expanded.

1 Intake Passage 5 Turbocharger 17 Combustion Chamber 20 Fuel Injection Valve 21 Glow Plug 41 Exhaust Passage 43 High Pressure EGR Device 45 DOC
46 DPF
48 Low pressure EGR device 60 Control device 200 Engine system E Engine

To achieve the above object, the present invention is a control method for a diesel engine comprising a fuel injection valve and the supercharger mounted in the combustion chamber top so that directly injects fuel into a combustion chamber, a fuel injection valve A step of determining whether or not deposits are accumulated , a step of controlling the fuel injection amount and fuel injection timing of the fuel injection valve based on the required torque during vehicle travel, and a determination that deposits are accumulated, In addition, when the vehicle is being serviced and the output of the diesel engine is not transmitted to the wheels, the predetermined operation for executing the deposit burnout control for burning the deposit accumulated on the fuel injection valve was performed. If, the request ignition timing for obtaining the in-cylinder temperature at compression top dead center needed to burn off a deposit, the most advance side relative to compression top dead center The minimum engine speed towards the is ignitable timing advance side ignition timing limit becomes the advance angle side, and setting on the basis of the supercharging pressure by the supercharger, the current engine speed is the minimum engine speed than In some cases, in order to start combustion at the required ignition timing, the fuel injection timing of the fuel injection valve is set to the fuel injection timing at the same engine speed and the same required torque when the vehicle travels on the advance side of the compression top dead center. And a step of preventing the control to advance when the current engine rotational speed is less than the minimum engine rotational speed .
According to the present invention configured as described above, the minimum engine speed at which the advance side ignition timing limit is on the advance side with respect to the required ignition timing is set based on the supercharging pressure by the supercharger . Then, when it is determined that deposits are accumulated, control is performed to advance the fuel injection timing only when the current engine speed is equal to or higher than the minimum engine speed. Thereby, the required ignition timing or the ignition timing on the more advanced side than that can be appropriately realized by the control for advancing the fuel injection timing. Therefore, according to the present invention, the in-cylinder temperature can be raised and the deposit accumulated in the combustion chamber can be appropriately burned out.
In addition, when the control for advancing the fuel injection timing as described above is performed during actual vehicle travel, a sense of incongruity (especially noise) may occur. However, according to the present invention, the control is performed on the vehicle. Since it is performed during maintenance and non-running, the occurrence of such a sense of incongruity can be appropriately suppressed.

In the present invention, preferably, the minimum engine speed is set to a lower speed as the supercharging pressure by the supercharger is higher.
According to the present invention configured as described above, considering that the ignition environment in the combustion chamber is improved when the supercharging pressure by the supercharger is high, the minimum engine speed is decreased as the supercharging pressure is increased. Set to the number of revolutions. Thereby, the appropriate minimum engine speed according to the supercharging pressure can be set. In this case, regarding the control for advancing the fuel injection timing, the execution permission range defined by the engine speed can be expanded.

In the present invention, the vehicle preferably includes an auxiliary machine driven by a diesel engine, and the minimum engine speed is lower as the auxiliary machine driving resistance applied to the diesel engine to drive the auxiliary machine is higher. Set to a number.
According to the present invention configured as described above, it is possible to drive the auxiliary machine in consideration of the fact that when the auxiliary machine driving resistance is high, the amount of fuel injection applied at the same engine speed increases and the in-cylinder gas temperature rises. As the resistance increases, the minimum engine speed is set to a lower speed. Thereby, the appropriate minimum engine speed according to auxiliary machine drive resistance can be set. In this case, regarding the control for advancing the fuel injection timing, the execution permission range defined by the engine speed can be expanded.
In the present invention, preferably, the fuel injection valve includes a main body, an injection hole formed in the main body, and a concave portion provided at a position corresponding to the injection hole on the outer surface of the main body and having a larger diameter than the injection hole. Have.
In the present invention, preferably, the exhaust passage of the diesel engine is provided with a particulate filter that collects particulate matter in the exhaust gas, and the exhaust pressure between the upstream side and the downstream side of the particulate filter is reduced. Based on the difference, it is determined whether or not deposits have accumulated on the fuel injection valve.
In the present invention, it is preferable to perform a regeneration process for removing particulate matter collected in the particulate filter based on the difference in exhaust pressure between the upstream side and the downstream side of the particulate filter. Based on the execution frequency of the process, it is determined whether or not deposits are accumulated on the fuel injection valve.

In another aspect, in order to achieve the above object, the present invention provides a fuel injection valve , a supercharger, and a control for controlling the fuel injection valve attached to the upper portion of the combustion chamber so as to inject fuel directly into the combustion chamber. A control system for a diesel engine provided with a device, wherein the control device determines whether deposits are accumulated on the fuel injection valve , and determines the fuel injection amount and fuel injection of the fuel injection valve based on the required torque when the vehicle travels Control the timing, determine that deposits have accumulated, and burn out deposits deposited on the fuel injection valves when the vehicle is being serviced and the diesel engine output is not transmitted to the wheels when a predetermined operation is performed for the deposit burned control to request deposition for obtaining the in-cylinder temperature at compression top dead center needed to burn off a deposit Against time, the minimum engine speed towards the most advance advance side ignition timing limit is ignitable timing in the advance side relative to compression top dead center becomes the advance angle side, the supercharging pressure by the turbocharger If the current engine speed is equal to or greater than the minimum engine speed, the fuel injection timing of the fuel injection valve is set to be advanced from the compression top dead center to start combustion at the required ignition timing. While the control is performed to advance the fuel injection timing at the same engine speed and the same required torque during traveling, the control to advance the engine is not performed when the current engine speed is less than the minimum engine speed. It is comprised so that it may be characterized by the above-mentioned.
Also according to the present invention configured as described above, the required ignition timing or the ignition timing more advanced than that can be appropriately realized by the control for advancing the fuel injection timing, and the in-cylinder temperature is increased to increase the in-cylinder temperature. It is possible to appropriately burn off the deposit deposited on the substrate.

In the present invention, preferably, the control device sets the minimum engine speed to a lower speed as the supercharging pressure by the supercharger is higher.
According to the present invention configured as described above, an appropriate minimum engine speed can be set according to the supercharging pressure.

Claims (8)

A method for controlling a diesel engine comprising a fuel injection valve that directly injects fuel into a combustion chamber,
Determining whether deposits are deposited in the combustion chamber;
Controlling the fuel injection amount and fuel injection timing of the fuel injection valve based on the required torque during vehicle travel;
Based on the operating state of the diesel engine, the relationship between the engine speed and the achievable advance side ignition timing limit, and the required ignition time for burning off deposits accumulated in the combustion chamber are obtained, and the advance angle is determined. Setting a minimum engine speed at which a side ignition timing limit satisfies the required ignition timing;
When it is determined that the deposit is accumulated, the fuel injection of the fuel injection valve is performed when the current engine speed becomes equal to or higher than the minimum engine speed when the vehicle is being maintained and not running. Performing a control to advance the timing more than the fuel injection timing at the same engine speed and the same required torque when the vehicle is running;
A method for controlling a diesel engine, comprising: The diesel engine further includes a supercharger driven by the diesel engine,
The diesel engine control method according to claim 1, wherein the minimum engine speed is set to a lower speed as the supercharging pressure by the supercharger is higher.   The diesel engine control method according to claim 1 or 2, wherein the minimum engine speed is set to a higher speed as the fuel injection amount of the fuel injection valve is larger. The vehicle includes an auxiliary machine driven by the diesel engine,
4. The minimum engine speed is set to a lower speed as the auxiliary driving resistance applied to the diesel engine is higher for driving the auxiliary machine. 5. Of diesel engine control. A control system for a diesel engine comprising a fuel injection valve that directly injects fuel into a combustion chamber and a control device that controls the fuel injection valve,
The controller is
Determining whether deposits are deposited in the combustion chamber;
Controlling the fuel injection amount and fuel injection timing of the fuel injection valve based on the required torque during vehicle travel;
Based on the operating state of the diesel engine, the relationship between the engine speed and the achievable advance side ignition timing limit, and the required ignition time for burning off deposits accumulated in the combustion chamber are obtained, and the advance angle is determined. Set the minimum engine speed at which the side ignition timing limit satisfies the required ignition timing,
When it is determined that the deposit has accumulated, the fuel injection timing of the fuel injection valve when the current engine speed becomes equal to or greater than the minimum engine speed during maintenance of the vehicle and when the vehicle is not running A control system for a diesel engine, characterized in that control is performed to advance the angle of fuel from the fuel injection timing at the same engine speed and the same required torque when the vehicle is traveling. The diesel engine further includes a supercharger driven by the diesel engine,
The control system for a diesel engine according to claim 1, wherein the control device sets the minimum engine speed to a lower speed as the supercharging pressure by the supercharger is higher.   The control system for a diesel engine according to claim 5 or 6, wherein the control device sets the minimum engine speed to a higher speed as the fuel injection amount of the fuel injection valve increases. The vehicle includes an auxiliary machine driven by the diesel engine,
The control device according to any one of claims 5 to 7, wherein the minimum engine speed is set to a lower speed as an auxiliary machine driving resistance applied to the diesel engine for driving the auxiliary machine is higher. The diesel engine control system according to the item.

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