JP2012229628A - Deposit peeling amount estimation device and deposit deposition amount estimation device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate a deposit deposition amount or a peeling amount of an injection hole wall surface of a fuel injection valve.SOLUTION: A deposit peeling amount estimation device estimates a deposit peeling amount by calculating the deposit peeling amount as an amount of deposit peeled from an injection hole wall surface using a plurality of parameters representing factors affecting deposit peeling force as force to peel, from an injection hole wall surface, at least a part of deposit deposited on the injection hole wall surface as a wall surface defining a fuel injection hole 34 of a fuel injection valve, in an internal combustion engine provided with the fuel injection valve 22, wherein at least one parameter of the plurality of parameters is pressure of fuel injected from the fuel injection hole of the fuel injection valve, and the other one parameter of the plurality of parameters is pressure in the atmosphere around an exit of the fuel injection hole of the fuel injection valve.

Description

  The present invention relates to a deposit peeling amount estimation device and a deposit accumulation amount estimation device for an internal combustion engine.

  There is known an internal combustion engine in which a fuel injection valve is arranged so that fuel is directly injected into a combustion chamber. In such an internal combustion engine, combustion products (that is, fuel combustion related to the combustion of fuel) are formed on the wall surface near the injection hole outlet of the fuel injection valve (that is, the wall surface of the fuel injection valve near the outlet of the fuel injection hole). It is also known that substances produced by When combustion products accumulate on the wall surface near the nozzle hole outlet in this way, even if a command for injecting the desired amount of fuel to the fuel injection valve is sent to the fuel injection valve, An amount of fuel may not be injected. If the desired amount of fuel is not injected from the fuel injection valve, the output characteristics and exhaust characteristics of the internal combustion engine may deteriorate. Therefore, in order to know whether or not the desired amount of fuel may be injected from the fuel injection valve, the amount of combustion products accumulated on the wall surface near the nozzle hole outlet (hereinafter referred to as the wall near the nozzle hole outlet). It is not a little useful to know the combustion product accumulated in the deposit (also called “deposit”, and the amount of this deposit is called “total deposit accumulation amount”).

  By the way, during the engine operation (that is, during the operation of the internal combustion engine), the combustion products are successively generated. Here, all the combustion products generated one after another accumulate on the wall surface near the nozzle hole outlet, and the combustion product once deposited on the wall surface near the nozzle hole outlet (that is, deposit) does not peel off from the wall surface near the nozzle hole outlet. For example, the total deposit accumulation amount can be obtained by integrating the amount of combustion products generated one after another. However, in reality, the deposit may be separated from the wall surface near the outlet of the nozzle hole while combustion products are successively generated. Therefore, when determining the total deposit accumulation amount, it is necessary to consider not only the amount of combustion products generated one after another, but also the amount of deposit peeled off from the wall near the nozzle hole outlet.

  In Patent Document 1, the number of times fuel is injected from the fuel injection valve during one engine cycle (that is, during the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke) (hereinafter this number is referred to as “fuel injection”). Note that the amount of deposit peeled off from the fuel injection valve differs depending on the fuel pressure injected from the fuel injection valve (hereinafter referred to as “fuel injection pressure”). A technique for estimating the amount of deposit that peels from the fuel injection valve based on the number of times and the fuel injection pressure (hereinafter, this amount is referred to as “deposit peeling amount”) is described.

JP 2008-309131 A JP 2010-185419 A

  By the way, in the technique described in Patent Document 1, the deposit separation amount is estimated in consideration of the number of fuel injections and the fuel injection pressure in one engine cycle. However, in order to estimate the deposit separation amount more accurately, and more accurately to estimate the deposit accumulation amount, the number of fuel injections or fuel in one engine cycle is used for estimation of the deposit separation amount or estimation of the deposit accumulation amount. It has become clear from the inventor's research that it is necessary to consider factors other than the injection pressure.

  Accordingly, an object of the present invention is to accurately estimate the deposit peeling amount or the deposit accumulation amount.

  The invention of the present application relates to an internal combustion engine provided with a fuel injection valve, an injection hole defining wall that is a wall defining a fuel injection hole of the fuel injection valve, and a wall other than the injection hole defining wall, Deposited on the wall surface of the fuel injection valve in the vicinity of the inlet of the fuel injection hole and on the wall surface of the injection hole composed of at least one of the wall surfaces of the fuel injection valve in the vicinity of the outlet of the fuel injection hole. The amount of deposit peeling that is the amount of deposit that peels off the wall surface of the nozzle hole using a plurality of parameters that represent a factor that affects the deposit peeling force that is the force that peels at least a portion of the deposit from the wall surface of the nozzle hole. The present invention relates to a deposit peeling amount estimation device that estimates a deposit peeling amount by calculating. In the present invention, one of the plurality of parameters is a pressure of the fuel injected from the fuel injection hole of the fuel injection valve, and another one of the plurality of parameters is around the outlet of the fuel injection hole of the fuel injection valve. Atmospheric pressure.

  According to the present invention, the deposit peeling amount can be accurately estimated. That is, the fuel injection pressure (that is, the pressure of fuel injected from the fuel injection hole of the fuel injection valve) can be cited as a factor affecting the deposit separation amount. That is, if the fuel injection pressure varies, the deposit peeling amount also varies. However, even if the fuel injection pressure is constant, the amount of deposit peeling differs according to the pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve (hereinafter, this pressure is referred to as “outlet atmosphere pressure”). That is, even if the fuel injection pressure is constant, if the outlet atmosphere pressure is relatively high, the differential pressure between the fuel injection pressure and the outlet atmosphere pressure is relatively small, so the fuel flowing around the deposit (ie, the fuel injection hole) The flow velocity of the fuel that flows into the fuel inlet, flows through the fuel injection hole, and flows out from the outlet of the fuel injection hole is relatively slow. For this reason, the strength of the shearing action given to the deposit from the fuel flowing around the deposit is relatively weak, and the strength of the erosion in the cavitation generated around the deposit is also relatively weak. On the contrary, even if the fuel injection pressure is constant, if the outlet atmosphere pressure is relatively low, the differential pressure between the fuel injection pressure and the outlet atmosphere pressure is relatively large. fast. For this reason, the strength of the shearing action given to the deposit from the fuel flowing around the deposit is relatively strong, and the strength of the erosion in the cavitation generated around the deposit is also relatively strong. Here, if the strength of the shearing action is weak, the amount of deposit peeling is small, and if the strength of the erosion is weak, the amount of deposit peeling is small. On the contrary, if the strength of the shearing action is high, the amount of deposit peeling is large, and if the strength of the erosion is strong, the amount of deposit peeling is large. That is, if the outlet atmospheric pressure is high, the amount of deposit peeling is small. Conversely, if the outlet atmospheric pressure is low, the amount of deposit peeling is large. As described above, the inventors' research has revealed that the outlet atmosphere pressure affects the deposit peeling amount. Therefore, in order to estimate the deposit peeling amount more accurately, the influence of the outlet atmosphere pressure on the deposit peeling amount should be considered in the estimation of the deposit peeling amount. In the present invention, since the outlet atmospheric pressure is taken into account in estimating the deposit peeling amount, according to the present invention, the deposit peeling amount can be accurately estimated.

  Since the present invention is a deposit delamination amount estimating device for estimating the amount of deposit delamination from the wall surface of the injection hole of the fuel injection valve, the present invention is an internal combustion engine equipped with a fuel injection valve in which deposit is deposited on the wall surface of the injection hole. The present invention can be applied to any internal combustion engine. Therefore, the fuel injection valve according to the present invention is not limited to a specific fuel injection valve as long as deposits are accumulated on the wall surface of the injection hole. For example, the tip of the fuel injection valve can be directly injected into the combustion chamber. It may be a type of fuel injection valve that is exposed in the combustion chamber (so-called in-cylinder type fuel injection valve), or its tip is in the intake port so that fuel can be injected into the intake port. It may be an exposed type fuel injection valve (a so-called port injection type fuel injection valve).

  In the present invention, the outlet atmospheric pressure used as another one of the plurality of parameters is, for example, the outlet atmospheric pressure when fuel is injected from the fuel injection hole of the fuel injection valve. However, in the present invention, the outlet atmospheric pressure used as another one of the plurality of parameters is not limited to the outlet atmospheric pressure described above. That is, in the present invention, the outlet atmospheric pressure used as another one of the plurality of parameters is not limited as long as the deposit peeling amount varies due to the variation of the outlet atmospheric pressure even if the fuel injection pressure is constant. The outlet atmospheric pressure may be used.

  Another invention of the present application is an internal combustion engine provided with a fuel injection valve, which includes a nozzle hole defining wall surface that defines a fuel injection hole of the fuel injection valve, and a wall surface other than the nozzle hole defining wall surface. A nozzle hole comprising at least one of a wall surface of the fuel injection valve near the inlet of the fuel injection hole and a wall surface other than the nozzle hole defining wall surface and near the outlet of the fuel injection hole The present invention relates to a deposit accumulation amount estimation apparatus that estimates a deposit accumulation amount by calculating a deposit accumulation amount that is an amount of deposits accumulated on a wall surface. And this invention has the deposit peeling amount estimation apparatus of the said invention. In the present invention, the generation amount of the deposit constituent material constituting the deposit is estimated as the deposit constituent material generation amount, and the deposit peeling amount estimation device estimates the deposit peeling amount. Then, the deposit accumulation amount is calculated by subtracting the deposit peeling amount from the deposit constituent generation amount.

  According to the present invention, the deposit accumulation amount can be accurately estimated. That is, as described above, according to the deposit peeling amount estimation device of the invention, it is possible to accurately estimate the deposit peeling amount necessary for calculating the deposit accumulation amount. And in this invention, the deposit peeling amount estimation apparatus of the said invention is utilized for estimation of the deposit peeling amount. Therefore, the deposit accumulation amount can be accurately estimated.

  Further, in still another invention of the present application, in the above invention, the deposit peeling amount during a predetermined period is calculated, and fuel injection from the fuel injection valve is executed a plurality of times during the predetermined period. In the fuel injection valve, the lowest pressure among the atmospheric pressures around the outlet of the fuel injection hole of the fuel injection valve at the time of execution of each fuel injection during the predetermined period is used for calculating the deposit separation amount. Adopted as atmospheric pressure around the outlet of the injection hole.

  According to the present invention, it is possible to accurately estimate the deposit separation amount or the deposit accumulation amount even when the fuel injection from the fuel injection valve is executed a plurality of times during a predetermined period. That is, when fuel injection from the fuel injection valve is executed a plurality of times during a predetermined period, the pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve at the time when each fuel injection is executed (hereinafter referred to as this The pressure may be different for each fuel injection. In this case, the amount of deposit separation during a predetermined period is determined for the fuel injection executed at the time when the outlet atmospheric pressure is the lowest among these fuel injections. That is, the higher the outlet atmospheric pressure, the smaller the amount of deposit peeling, and the lower the outlet atmospheric pressure, the larger the amount of deposit peeling. Therefore, even if the deposit is peeled off from the nozzle hole wall surface by the fuel injection performed before the time when the outlet atmospheric pressure is the lowest, the deposit is made from the nozzle hole wall surface by the fuel injection performed when the outlet atmosphere pressure is the lowest. Is further peeled off. In this case, the fuel injection performed at the time when the outlet atmospheric pressure is the lowest determines the deposit peeling amount. Further, even if fuel injection is performed after the time when the outlet atmospheric pressure is the lowest, the deposit that can be peeled off by the fuel injection is peeled off by the fuel injection executed when the outlet atmospheric pressure is the lowest. Further, the deposit is not further peeled off from the wall surface of the nozzle hole by the fuel injection performed after the time when the outlet atmospheric pressure is the lowest. Also in this case, the fuel injection executed at the time when the outlet atmospheric pressure is the lowest determines the deposit peeling amount. In the present invention, the outlet atmospheric pressure at the time when the fuel injection that determines the deposit peeling amount during the predetermined period is executed is used for calculating the deposit peeling amount during the predetermined period. The deposit peeling amount during a predetermined period calculated by using the outlet atmospheric pressure at the time when the fuel injection that determines the deposit peeling amount during the predetermined period is executed is used for calculating the deposit accumulation amount. Therefore, according to the present invention, it is possible to accurately estimate the deposit separation amount or the deposit accumulation amount even when fuel injection from the fuel injection valve is executed a plurality of times during a predetermined period.

  Still another invention of the present application is directed to an internal combustion engine provided with a fuel injection valve, including an injection hole defining wall that is a wall defining a fuel injection hole of the fuel injection valve, and a wall other than the injection hole defining wall. A jet comprising at least one of a wall surface of the fuel injection valve near the inlet of the fuel injection hole and a wall surface other than the injection hole defining wall surface and near the outlet of the fuel injection hole. The present invention relates to a deposit accumulation amount estimation device that estimates a deposit accumulation amount by calculating a deposit accumulation amount that is an amount of deposits accumulated on a hole wall surface. In the present invention, the amount of the substance generated as the deposit constituent material constituting the deposit is estimated as the deposit constituent material generation amount, and the deposit stripping amount which is the amount of the deposit stripped from the wall surface of the nozzle hole is the fuel injection valve. It is estimated using the pressure of the fuel injected from the fuel injection hole. Then, a provisional deposit accumulation amount is calculated by subtracting the deposit peeling amount from the deposit constituent generation amount. Then, the final deposit accumulation amount is calculated by correcting the provisional deposit accumulation amount in consideration of the pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve.

  According to the present invention, the deposit accumulation amount can be accurately estimated. That is, the fuel injection pressure (that is, the pressure of fuel injected from the fuel injection hole of the fuel injection valve) can be cited as a factor affecting the deposit separation amount. That is, if the fuel injection pressure varies, the deposit peeling amount also varies. However, even if the fuel injection pressure is constant, the amount of deposit peeling differs according to the pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve (hereinafter, this pressure is referred to as “outlet atmosphere pressure”). That is, even if the fuel injection pressure is constant, if the outlet atmosphere pressure is relatively high, the differential pressure between the fuel injection pressure and the outlet atmosphere pressure is relatively small, so the fuel flowing around the deposit (ie, the fuel injection hole) The flow velocity of the fuel that flows into the fuel inlet, flows through the fuel injection hole, and flows out from the outlet of the fuel injection hole is relatively slow. For this reason, the strength of the shearing action given to the deposit from the fuel flowing around the deposit is relatively weak, and the strength of the erosion in the cavitation generated around the deposit is also relatively weak. On the contrary, even if the fuel injection pressure is constant, if the outlet atmosphere pressure is relatively low, the differential pressure between the fuel injection pressure and the outlet atmosphere pressure is relatively large. fast. For this reason, the strength of the shearing action given to the deposit from the fuel flowing around the deposit is relatively strong, and the strength of the erosion in the cavitation generated around the deposit is also relatively strong. Here, if the strength of the shearing action is weak, the amount of deposit peeling is small, and if the strength of the erosion is weak, the amount of deposit peeling is small. On the contrary, if the strength of the shearing action is high, the amount of deposit peeling is large, and if the strength of the erosion is strong, the amount of deposit peeling is large. That is, if the outlet atmospheric pressure is high, the amount of deposit peeling is small. Conversely, if the outlet atmospheric pressure is low, the amount of deposit peeling is large. As described above, the inventors' research has revealed that the outlet atmosphere pressure affects the deposit peeling amount. Therefore, in order to estimate the deposit accumulation amount more accurately, the influence of the outlet atmosphere pressure on the deposit peeling amount should be considered in the estimation of the deposit accumulation amount. In the present invention, since the outlet atmospheric pressure is taken into account in the estimation of the deposit amount, according to the present invention, the deposit amount can be accurately estimated.

  Since the present invention is a deposit accumulation amount estimation device for estimating the amount of deposit accumulated on the wall surface of the injection hole of the fuel injection valve, the present invention is an internal combustion engine equipped with a fuel injection valve in which deposit is accumulated on the wall surface of the injection hole. The present invention can be applied to any internal combustion engine. Therefore, the fuel injection valve according to the present invention is not limited to a specific fuel injection valve as long as deposits are accumulated on the wall surface of the injection hole. For example, the tip of the fuel injection valve can be directly injected into the combustion chamber. It may be a type of fuel injection valve that is exposed in the combustion chamber (so-called in-cylinder type fuel injection valve), or its tip is in the intake port so that fuel can be injected into the intake port. It may be an exposed type fuel injection valve (a so-called port injection type fuel injection valve).

  In the present invention, the outlet atmospheric pressure considered for the provisional deposit accumulation correction is, for example, the outlet atmospheric pressure when fuel is injected from the fuel injection hole of the fuel injection valve. However, in the present invention, the outlet atmospheric pressure considered for the provisional deposit accumulation correction is not limited to the outlet atmospheric pressure described above. That is, in the present invention, the outlet atmosphere pressure that is considered for the provisional deposit accumulation amount correction, even if the fuel injection pressure is constant, as long as the deposit peeling amount varies due to the variation of the outlet atmosphere pressure, Any outlet atmospheric pressure may be used.

  Further, in still another invention of the present application, in the above invention, the deposit peeling amount during a predetermined period is calculated, and fuel injection from the fuel injection valve is executed a plurality of times during the predetermined period. In the fuel injection, the lowest pressure among the pressures of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve at the time of execution of each fuel injection during the predetermined period is used for provisional deposit correction correction Adopted as atmospheric pressure around the outlet of the fuel injection hole of the valve.

  According to the present invention, it is possible to accurately estimate the deposit accumulation amount even when the fuel injection from the fuel injection valve is executed a plurality of times during a predetermined period. That is, when fuel injection from the fuel injection valve is executed a plurality of times during a predetermined period, the pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve at the time when each fuel injection is executed (hereinafter referred to as this The pressure may be different for each fuel injection. In this case, the amount of deposit separation during a predetermined period is determined for the fuel injection executed at the time when the outlet atmospheric pressure is the lowest among these fuel injections. That is, the higher the outlet atmospheric pressure, the smaller the amount of deposit peeling, and the lower the outlet atmospheric pressure, the larger the amount of deposit peeling. Therefore, even if the deposit is peeled off from the nozzle hole wall surface by the fuel injection performed before the time when the outlet atmospheric pressure is the lowest, the deposit is made from the nozzle hole wall surface by the fuel injection performed when the outlet atmosphere pressure is the lowest. Is further peeled off. In this case, the fuel injection performed at the time when the outlet atmospheric pressure is the lowest determines the deposit peeling amount. Further, even if fuel injection is performed after the time when the outlet atmospheric pressure is the lowest, the deposit that can be peeled off by the fuel injection is peeled off by the fuel injection executed when the outlet atmospheric pressure is the lowest. Further, the deposit is not further peeled off from the wall surface of the nozzle hole by the fuel injection performed after the time when the outlet atmospheric pressure is the lowest. Also in this case, the fuel injection executed at the time when the outlet atmospheric pressure is the lowest determines the deposit peeling amount. In the present invention, the outlet atmospheric pressure at the time when the fuel injection for determining the deposit separation amount during the predetermined period is executed is used for provisional deposit accumulation correction. For this reason, according to the present invention, it is possible to accurately estimate the deposit accumulation amount even when fuel injection from the fuel injection valve is executed a plurality of times during a predetermined period.

It is the figure which showed the internal combustion engine to which the deposit peeling amount estimation apparatus or the deposit amount accumulation amount estimation apparatus of the present invention is applied. It is the figure which showed the front-end | tip part of the fuel injection valve of the internal combustion engine shown by FIG. It is the figure which showed the routine which performs calculation of the total deposit accumulation amount according to 1st Embodiment. It is the figure which showed the routine which performs calculation of the total deposit accumulation amount according to 2nd Embodiment. It is the figure which showed the routine which performs calculation of the total deposit accumulation amount according to 3rd Embodiment. It is the figure which showed the routine which performs calculation of the total deposit accumulation amount according to 4th Embodiment.

  Hereinafter, an embodiment of a deposit peeling amount estimation device of the present invention will be described with reference to the drawings. First, the configuration of an internal combustion engine to which the deposit separation amount estimation apparatus of the present invention is applied will be described. This internal combustion engine is shown in FIG. In FIG. 1, 10 is a main body of the internal combustion engine, 11 is a cylinder block, and 12 is a cylinder head. A cylinder bore 13 is formed in the cylinder block 11. A piston 14 is disposed in the cylinder bore 13. The piston 14 is connected to the crankshaft 16 via a connecting rod 15. On the other hand, an intake port 17 and an exhaust port 18 are formed in the cylinder head 12. The cylinder head 12 is also provided with an intake valve 19 for opening and closing the intake port 17 and an exhaust valve 20 for opening and closing the exhaust port 18. A combustion chamber 21 is defined by the upper wall surface of the piston 14, the inner peripheral wall surface of the cylinder bore 13, and the lower wall surface of the cylinder head 12.

  The intake port 17 is connected to an intake pipe (not shown) via an intake manifold (not shown) and constitutes a part of the intake passage. On the other hand, the exhaust port 18 is connected to an exhaust pipe (not shown) via an exhaust manifold (not shown) and constitutes a part of the exhaust passage.

  A fuel injection valve 22 is disposed in the cylinder head 12. As shown in FIG. 2, the fuel injection valve 22 has a nozzle 30 and a needle 31. A cavity (hereinafter referred to as “internal cavity”) is formed inside the nozzle 30. And in this internal cavity, the needle 31 is accommodated so that the movement along the center axis line (namely, center axis line of the fuel injection valve 22) CA of the nozzle 30 is possible. The tip of the needle 31 is tapered. When the needle 31 is accommodated in the internal cavity of the nozzle 30, fuel is passed between the inner peripheral wall surface of the nozzle 30 (that is, the wall surface defining the internal cavity of the nozzle 30) and the outer peripheral wall surface of the needle 31. A fuel passage 32 is formed. The fuel passage 32 at the tip of the nozzle 30 forms a so-called sac 33 (hereinafter, the fuel passage 32 means a fuel passage excluding the sack 33). Furthermore, a plurality of fuel injection holes 34 are formed at the tip of the nozzle 30. These fuel injection holes 34 communicate between the sac 33 in the nozzle 30 (that is, in the fuel injection valve 22) and the outside of the nozzle 30 (that is, outside the fuel injection valve 22).

  When the needle 31 is positioned in the nozzle 30 so that the outer peripheral wall surface of the tapered tip portion of the needle 31 is in contact with the inner peripheral wall surface of the nozzle 30, the gap between the suck 33 and the fuel passage 32 is set. Communication is interrupted. At this time, fuel is not injected from the fuel injection hole 34 of the fuel injection valve 22. On the other hand, when the needle 31 is moved in the nozzle 30 so that the outer peripheral wall surface of the tapered tip portion of the needle 31 is separated from the inner peripheral wall surface of the nozzle 30, the sac 33 and the fuel passage 32 communicate with each other. The fuel flows into the fuel passage 32 or the sac 33. The fuel that has flowed into the sac 33 flows into the fuel injection hole 34 through the inlet of the fuel injection hole 34 and is injected from the outlet through the fuel injection hole 34.

  The fuel injection valve 22 is disposed in the cylinder head 12 so as to directly inject fuel into the combustion chamber 21. In other words, the fuel injection valve 22 is arranged in the cylinder head 12 so that the fuel injection hole is exposed in the combustion chamber 21.

  The fuel injection valve 22 is connected to a pressure accumulating chamber (that is, a so-called common rail) 24 through a fuel supply passage 23. The pressure accumulating chamber 24 is connected to a fuel tank (not shown) via a fuel supply passage 25. Fuel is supplied to the pressure accumulating chamber 24 from a fuel tank through a fuel supply passage 25. A high-pressure fuel is stored in the pressure accumulating chamber 24. Further, high pressure fuel is supplied to the fuel injection valve 22 from the pressure accumulation chamber 24 through the fuel supply passage 23. The pressure accumulating chamber 24 is provided with a pressure sensor 26 for detecting the pressure of the fuel inside.

  Further, a cooling water passage 27 for flowing cooling water is formed in the cylinder block 11. The cooling water passage 27 is formed so as to surround the cylinder bore 13. Therefore, at least the inside of the combustion chamber 21 is cooled by the cooling water flowing in the cooling water passage 27. The cylinder block 11 is provided with a temperature sensor 28 for detecting the temperature of the cooling water flowing in the cooling water passage 27.

  The internal combustion engine has an electronic control unit 40. The electronic control unit 40 includes a microcomputer, and is connected to each other by a bidirectional bus 41. A CPU (microprocessor) 42, a ROM (read only memory) 43, a RAM (random access memory) 44, a backup RAM 45, and an interface 46 are connected. Have The interface 46 is connected to the fuel injection valve 22, the pressure sensor 26, the temperature sensor 28, and the in-cylinder pressure sensor 29. The electronic control unit 40 controls the operation of the fuel injection valve 22, receives an output value corresponding to the fuel pressure from the pressure sensor 26, and receives an output value corresponding to the coolant temperature from the temperature sensor 28.

  In the above-described internal combustion engine, fuel injection (that is, fuel injection) in the vicinity of the compression top dead center during one engine cycle (that is, an engine in which an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are performed in the combustion chamber). Injection of fuel from the valve).

  Next, an embodiment of the deposit peeling amount estimation device and deposit accumulation amount estimation device of the present invention applied to the above-described internal combustion engine will be described. In the following description, “the injection hole defining wall surface” is “the fuel injection valve wall surface defining the fuel injection hole of the fuel injection valve”, and “the injection hole inlet near wall surface” is “the fuel injection hole of the fuel injection valve”. The fuel injection valve wall surface adjacent to the nozzle hole defining wall in the vicinity of the inlet of the fuel injection port, and the “wall surface near the nozzle hole outlet” in the vicinity of the outlet of the fuel injection hole of the fuel injection valve The valve wall. “Combustion products” are “substances generated in connection with fuel combustion”, “combustion gas” is “gas generated by burning fuel in the combustion chamber”, and “fuel injection” Is “injection of fuel from the fuel injection hole of the fuel injection valve”, “fuel injection pressure” is “pressure of fuel injected from the fuel injection hole of the fuel injection valve”, and “injection hole temperature” is “ The temperature inside the fuel injection hole of the fuel injection valve ”.

  In an internal combustion engine in which a fuel injection valve is arranged so that fuel is directly injected into the combustion chamber, it is known that combustion products accumulate on the wall surface near the injection hole outlet of the fuel injection valve. In addition, the metal component in the fuel (for example, zinc, calcium, magnesium, etc.) reacts with the combustion gas to produce a combustion product derived from the metal component (for example, a lower carboxylate, carbonate, oxalate, etc., This combustion product is hereinafter referred to as “metal-derived product”), and it has been clarified by the inventor's research that this metal-derived product is also deposited on the wall near the nozzle hole outlet. In addition, it has been clarified by the inventors' research that this metal-derived product is also deposited on the wall defining the nozzle hole and the wall near the nozzle inlet. Hereinafter, this metal-derived product will be briefly described.

  Conventionally, it has been recognized that combustion products do not accumulate on the nozzle hole defining wall surface or the wall surface near the nozzle hole inlet. However, according to the research of the inventors of the present application, as described above, combustion products in the form of metal-derived products are deposited not only on the wall surface near the nozzle hole outlet but also on the wall surface defining the nozzle hole and the wall surface near the nozzle hole inlet. It became clear to do. The reason why the metal-derived product accumulates on the nozzle hole defining wall surface and the wall surface near the nozzle hole inlet is presumed as follows. That is, when the fuel injection valve is arranged in the internal combustion engine so that the fuel injection valve directly injects the fuel into the combustion chamber, that is, the fuel injection hole of the fuel injection valve is exposed in the combustion chamber, Enters the fuel injection hole, and this combustion gas reacts with the fuel in the fuel injection hole and in the vicinity of the inlet to produce a metal-derived product. And since the adhesion force of the metal-derived product to the wall surface is relatively strong, the injection hole defining wall and the wall near the injection hole inlet, despite the strong fuel flow in the fuel injection hole and at the inlet thereof Adhere to and deposit. This is presumed to be the reason why the metal-derived product is deposited on the nozzle hole defining wall surface and the wall surface near the nozzle hole inlet.

  By the way, the combustion product (hereinafter referred to as the “hole surface” hereinafter) containing the metal-derived product on the wall surface near the nozzle hole outlet, the wall surface defining the nozzle hole, and the wall surface near the nozzle hole inlet (hereinafter collectively referred to as “hole surface”). When the combustion product contains a metal-derived product), the combustion product deposited on the nozzle hole wall (hereinafter, deposited on the nozzle hole wall in this way) Combustion products called “deposits”) impede fuel flow. Therefore, even if a command value that can cause the fuel injection valve to inject the fuel that is originally required (hereinafter, this amount is referred to as “required fuel injection amount”) to the fuel injection valve is required. There is a possibility that the fuel injection amount of fuel is not injected from the fuel injection valve.

  If the required fuel injection amount of fuel is not injected from the fuel injection valve, the output characteristics and exhaust characteristics of the internal combustion engine may deteriorate. Therefore, it is indispensable to know whether or not there is a possibility that such deterioration of the internal combustion engine's output characteristics and exhaust characteristics will be suppressed or improved, and such characteristics may be deteriorated. Knowing the presence or absence of sex is not a little useful. In order to know whether or not there is a possibility of such a characteristic deterioration, it is necessary to accurately know the amount of deposit deposited on the wall surface of the nozzle hole (this amount is hereinafter referred to as “total deposit accumulation amount”). is there.

  By the way, during engine operation (that is, during operation of the internal combustion engine), fuel is successively injected from the fuel injection valve, so that combustion products are generated one after another. Here, if the combustion products generated one after another are accumulated on the wall surface of the nozzle hole and the combustion products once deposited on the wall surface of the nozzle hole (that is, deposit) are not separated from the wall surface of the nozzle hole, If the amount of the fuel product produced is integrated, the total deposit accumulation amount can be obtained accurately.

  However, in reality, the combustion products are generated one after another, and deposits may be separated from the wall surface of the nozzle hole while these combustion products are deposited on the wall surface of the nozzle hole. That is, when it is desired to accurately determine the total deposit accumulation amount, it is necessary to consider not only the amount of combustion products generated one after another, but also the amount of deposit that peels from the nozzle hole wall surface.

  Therefore, in this embodiment (hereinafter referred to as “first embodiment”), the in-cylinder pressure (that is, the pressure in the combustion chamber) at the time of execution of fuel injection performed during one engine cycle is acquired. Then, a deposit peeling amount (hereinafter, this deposit peeling amount is referred to as “a new deposit peeling amount”) Xr during a predetermined period (that is, a predetermined period) is calculated according to the following formula 1. The predetermined period is not particularly limited, and may be set arbitrarily. For example, the predetermined period is a period of the one engine cycle.

  Xr = Fxr (Pin, Pc) (1)

  “Pin” in Equation 1 is “fuel injection pressure during fuel injection” (hereinafter simply referred to as “fuel injection pressure”). The fuel injection pressure is obtained from the output value of the pressure sensor 26, for example. Further, “Pc” in Expression 1 is “in-cylinder pressure at the time of execution of fuel injection (hereinafter referred to as“ in-cylinder pressure during injection ”)”. The in-cylinder pressure at the time of injection is obtained from the output value of the in-cylinder pressure sensor 29, for example. Further, “Fxr” in Expression 1 is a function adapted so that the new deposit separation amount can be accurately calculated using these fuel injection pressure and in-cylinder in-cylinder pressure as parameters. As shown in Expression 1, the new deposit separation amount Xr is calculated as a function of the fuel injection pressure Pin and the in-cylinder pressure Pc during injection. Note that the deposit new peel amount calculated according to Equation 1 increases as the fuel injection pressure increases and increases as the in-cylinder pressure during injection decreases.

  By the way, in the first embodiment, the amount of combustion products generated during the predetermined period (hereinafter, this amount of generation is referred to as “a new amount of generation of combustion products”) Xp is calculated according to the following equation 2.

  Xp = Cm × a × Tn (2)

  “Cm” in Equation 2 is “the concentration of the metal component in the fuel” (hereinafter simply referred to as “metal component concentration”). This metal component concentration may be, for example, a concentration measured in advance or a concentration measured as appropriate during engine operation. Further, “Tn” in Expression 2 is “a nozzle hole temperature at a specific time point in the predetermined period (hereinafter, simply referred to as“ hole nozzle temperature ”)”. The nozzle hole temperature is obtained, for example, from the output value of the temperature sensor 28 at a specific point in time during the predetermined period. Of course, instead of the nozzle hole temperature at a specific point in time during the predetermined period, the average nozzle hole temperature during the predetermined period may be used. In addition, “Tn” in Expression 2 is not limited to this nozzle hole temperature, and may be, for example, the temperature of the atmosphere in the vicinity of the outlet of the fuel injection hole of the fuel injection valve at a specific point in time during the predetermined period. It may be the temperature of the atmosphere in the vicinity of the inlet of the fuel injection hole of the fuel injection valve at a specific point in time. Of course, any temperature other than these temperatures may be used as long as it affects the amount of new combustion products generated. In addition, “a” in Equation 2 is a coefficient adapted to accurately calculate the new amount of combustion product generated related to the metal component concentration Cm and the nozzle hole temperature Tn. As shown in Equation 2, the new combustion product generation amount Xp is calculated based on the product of the metal component concentration Cm and the nozzle hole temperature Tn. In other words, the new combustion product generation amount Xp is calculated as a function of the metal component concentration Cm and the nozzle hole temperature Tn. The new combustion product generation amount Xp calculated according to Equation 2 increases as the metal component concentration Cm increases and increases as the nozzle hole temperature Tn increases.

  In the first embodiment, the deposit accumulation amount (hereinafter referred to as “deposit deposit amount”) Xd during the predetermined period is calculated according to the following equation 3.

  Xd = Xp-Xr (3)

  Note that “Xp” in Equation 3 is the new amount of combustion product calculated according to Equation 2. Further, “Xr” in Expression 3 is a deposit new peel amount calculated according to Expression 1. As shown in Expression 3, the new deposit amount Xd is calculated by subtracting the new deposit amount Xr from the new combustion product generation amount Xp.

  In the first embodiment, the current total deposit accumulation amount TXd is calculated according to the following equation 4.

  TXd = TXd + Xd (4)

  Note that “TXd” on the left side of Equation 4 is the total deposit accumulation amount calculated this time according to Equation 4. Further, “TXd” on the right side of Equation 4 is the total deposit accumulation amount calculated last time according to Equation 4. Further, “Xd” in Equation 4 is the deposit new deposition amount calculated this time according to Equation 3. As shown in Equation 4, the total deposit accumulation amount TXd is calculated by integrating the new deposit accumulation amount Xd.

  According to the first embodiment, the deposit peeling amount can be accurately estimated. That is, the fuel injection pressure is a factor that affects the deposit peeling amount. That is, if the fuel injection pressure varies, the deposit peeling amount also varies. However, even if the fuel injection pressure is constant, the deposit peeling amount varies depending on the in-cylinder pressure at the time of injection. In other words, even if the fuel injection pressure is constant, if the in-cylinder pressure at the time of injection is relatively high, the differential pressure between the fuel injection pressure and the in-cylinder pressure at the time of injection is relatively small. The flow velocity of the fuel that flows into the inlet of the injection hole, flows through the fuel injection hole, and flows out of the outlet of the fuel injection hole is relatively slow. For this reason, the strength of the shearing action given to the deposit from the fuel flowing around the deposit is relatively weak, and the strength of the erosion in the cavitation generated around the deposit is also relatively weak. On the contrary, even if the fuel injection pressure is constant, if the in-cylinder pressure during injection is relatively low, the differential pressure between the fuel injection pressure and the in-cylinder pressure during injection is relatively large. Relatively fast. For this reason, the strength of the shearing action given to the deposit from the fuel flowing around the deposit is relatively strong, and the strength of the erosion in the cavitation generated around the deposit is also relatively strong. Here, if the strength of the shearing action is weak, the amount of deposit peeling is small, and if the strength of the erosion is weak, the amount of deposit peeling is small. On the contrary, if the strength of the shearing action is high, the amount of deposit peeling is large, and if the strength of the erosion is strong, the amount of deposit peeling is large. That is, if the in-cylinder pressure is high, the amount of deposit separation is small, and conversely, if the in-cylinder pressure is low, the amount of deposit separation is large. As described above, the inventor's research has revealed that the in-cylinder pressure during injection affects the deposit peeling amount. Therefore, in order to estimate the deposit peeling amount more accurately, the influence of the in-cylinder pressure at the time of injection on the deposit peeling amount should be considered in the estimation of the deposit peeling amount. In the first embodiment, since the in-cylinder pressure at the time of injection is considered in the calculation of the deposit peeling amount, according to the first embodiment, the deposit peeling amount can be accurately estimated.

  Of course, in the first embodiment, the deposit accumulation amount is calculated using the deposit peeling amount that is accurately estimated. Therefore, according to the first embodiment, the deposit accumulation amount can be accurately estimated.

  In the first embodiment, the total deposit accumulation amount that is the amount of deposit accumulated on the nozzle hole wall surface is estimated. However, the idea of the present invention included in the first embodiment can also be applied when estimating the thickness of deposits deposited on the nozzle hole wall surface.

  Further, in the first embodiment, the new deposit amount peeled from the wall near the nozzle hole outlet, the wall defining the nozzle hole, and the wall near the nozzle hole inlet is estimated, and the new deposit amount deposited on these wall surfaces and Total deposit accumulation is estimated. However, the idea of the present invention included in the first embodiment is to estimate a new deposit separation amount that peels from any one of the wall surface near the nozzle hole outlet, the wall surface defining the nozzle hole, and the wall surface near the nozzle hole inlet. And it is applicable also when estimating the deposit new deposit amount and total deposit deposit amount deposited on the said one wall surface.

  In addition, since “metal concentration in the fuel” is included as a parameter in Equation 2 used to calculate the new amount of combustion products generated, all the deposits deposited on the wall surface of the nozzle hole in the first embodiment Or it turns out that it is embodiment presupposed that most are comprised from the metal origin product. However, instead of Equation 2, a new combustion product generation amount is calculated on the assumption that all or most of the deposits deposited on the wall surface of the nozzle hole are composed of combustion products other than metal-derived products. Formula may be used, and the amount of new product of combustion product is calculated on the assumption that the deposit deposited on the wall of the nozzle hole is composed of metal-derived products and other combustion products An equation for doing so may be used.

  The fuel injection pressure (that is, the pressure of the fuel injected from the fuel injection hole of the fuel injection valve) is compared with the case where all or most of the deposit deposited on the wall surface of the injection hole is made of a metal-derived product. Is the case. In other words, the combustion products that are conventionally recognized as deposits deposited on the wall surface of the nozzle hole are different from the metal-derived products (for example, lower carboxylates such as zinc, calcium, magnesium, carbonates, oxalates, etc.). If the fuel injection pressure is a relatively high pressure within the practical range, the deposit made of the combustion product is separated from the wall surface of the injection hole by the fuel flowing in the fuel injection hole. However, deposits made of metal-derived products are not easily separated from the wall surface of the nozzle hole by the fuel flowing through the fuel injection hole even if the fuel injection pressure is relatively high within the practical range. For this reason, the case where all or most of the deposit deposited on the wall surface of the nozzle hole is made of a metal-derived product is a case where the fuel injection hole is relatively high.

  Further, by continuously accumulating the new deposit amount, the total deposit amount at that time can be calculated. However, there is a limit to the amount of deposit that can be deposited on the wall surface of the nozzle hole. The limit value of the amount of deposit that can be deposited on the wall surface of the nozzle hole (hereinafter, this limit value is referred to as “saturated deposit accumulation amount”) depends on the fuel injection pressure. More specifically, the higher the fuel injection pressure, the smaller the saturated deposit accumulation amount. Therefore, in the first embodiment, every time the total deposit accumulation amount is calculated, the saturated deposit accumulation amount corresponding to the fuel injection pressure is calculated. When the calculated total deposit accumulation amount is equal to or greater than the saturated deposit accumulation amount, the total deposit accumulation is calculated. The amount may be limited to a saturated deposit accumulation amount.

  Next, a routine for calculating the total deposit accumulation amount according to the first embodiment will be described. An example of this routine is shown in FIG. This routine is executed every one engine cycle.

  When the routine of FIG. 3 is started, in step 100, the fuel injection pressure Pin, the injection hole temperature Tn, the metal component concentration Cm, and the in-cylinder pressure Pc during injection are acquired. Next, at step 101, a saturated deposit accumulation amount TXdmax is calculated based on the fuel injection pressure Pin acquired at step 100. Next, in step 102, the new combustion product generation amount Xp is calculated by applying the nozzle hole temperature Tn and the metal component concentration Cm acquired in step 100 to the above equation 2, and the fuel acquired in step 100 is calculated. The deposit new peel amount Xr is calculated by applying the injection pressure Pin and the in-cylinder pressure Pc during injection to the above equation 1. Next, in step 103, a new deposit amount Xd is calculated by applying the new combustion product generation amount Xp and the new deposit separation amount Xr calculated in step 102 to the above equation 3. Next, in step 104, the total deposit accumulation amount TXd is calculated by applying the new deposit accumulation amount Xd calculated in step 103 to the above equation 4.

  Next, at step 105, it is determined whether or not the total deposit accumulation amount TXd calculated at step 104 is smaller than the saturated deposit accumulation amount TXdmax calculated at step 101 (TXd <TXdmax). Here, when it is determined that TXd <TXdmax, the routine proceeds to step 106. On the other hand, when it is determined that TXd ≧ TXdmax, the routine proceeds to step 107.

  When the routine proceeds to step 106, the total deposit accumulation amount TXd calculated in step 104 is set as the current total deposit accumulation amount as it is, and the routine ends.

  On the other hand, when the routine proceeds to step 107, the saturated deposit accumulation amount TXdmax calculated in step 101 is set as the current total deposit accumulation amount, and the routine is terminated.

  Next, a second embodiment will be described. In the second embodiment, the in-cylinder pressure at the time of execution of fuel injection performed during one engine cycle is acquired. Then, a deposit peeling amount (hereinafter, this deposit peeling amount is referred to as “a new deposit peeling amount”) Xr during a predetermined period (that is, a predetermined period) is calculated according to the following equation 5. The predetermined period is not particularly limited, and may be set arbitrarily. For example, the predetermined period is a period of the one engine cycle.

  Xr = b × Pin (5)

  “Pin” in Expression 5 is “fuel injection pressure during fuel injection (hereinafter simply referred to as“ fuel injection pressure ”)”. The fuel injection pressure is obtained from the output value of the pressure sensor 26, for example. Further, “b” in Equation 5 is a coefficient adapted so that the deposit separation amount related to the fuel injection pressure Pin is accurately calculated. As shown in Equation 5, the new deposit separation amount Xr is a deposit separation amount b × Pin that can be grasped in relation to the fuel injection hole Pin. In other words, the deposit new peel amount Xr is calculated as a function of the fuel injection hole Pin. And the deposit new peeling amount Xr calculated according to Formula 5 increases as the fuel injection hole Pin increases.

  In the second embodiment, the production amount of the combustion product (that is, the new combustion product production amount) Xp during the predetermined period is calculated according to the following equation 6.

  Xp = Cm × a × Tn (6)

  Note that “Cm” in Equation 6 is “concentration of metal component in fuel (that is, metal component concentration)”. This metal component concentration may be, for example, a concentration measured in advance or a concentration measured as appropriate during engine operation. Further, “Tn” in Expression 6 is “the nozzle hole temperature at a specific time point in the predetermined period (hereinafter, simply referred to as“ hole nozzle temperature ”)”. The nozzle hole temperature is obtained, for example, from the output value of the temperature sensor 28 at a specific point in time during the predetermined period. Of course, instead of the nozzle hole temperature at a specific point in time during the predetermined period, the average nozzle hole temperature during the predetermined period may be used. In addition, “Tn” in Expression 6 is not limited to the nozzle hole temperature, and may be, for example, the temperature of the atmosphere in the vicinity of the outlet of the fuel injection hole of the fuel injection valve at a specific time during the predetermined period. It may be the temperature of the atmosphere in the vicinity of the inlet of the fuel injection hole of the fuel injection valve at a specific point in time. Of course, any temperature other than these temperatures may be used as long as it affects the amount of new combustion products generated. Further, “a” in Equation 6 is a coefficient adapted to accurately calculate the new amount of combustion product generated related to the metal component concentration Cm and the nozzle hole temperature Tn. As shown in Equation 6, the new combustion product generation amount Xp is calculated based on the product of the metal component concentration Cm and the nozzle hole temperature Tn. In other words, the new combustion product generation amount Xp is calculated as a function of the metal component concentration Cm and the nozzle hole temperature Tn. The new combustion product generation amount Xp calculated according to Equation 6 increases as the metal component concentration Cm increases and increases as the nozzle hole temperature Tn increases.

  In the second embodiment, the deposit accumulation amount (that is, the provisional deposit new accumulation amount) PXd during the predetermined period is calculated according to the following equation 7.

  PXd = Xp−Xr (7)

  Note that “Xp” in Equation 7 is the new amount of combustion product calculated according to Equation 6. Further, “Xr” in Expression 7 is a deposit new peel amount calculated according to Expression 5. As shown in Equation 7, the temporary deposit new deposition amount PXd is calculated by subtracting the new deposit deposit amount Xr from the new combustion product generation amount Xp.

  In the second embodiment, the final new deposit amount Xd is calculated according to the following equation 8.

  Xd = Fxd (PXd, Pc) (8)

  Note that “PXd” in Expression 8 is the provisional deposit new deposition amount calculated according to Expression 7. Further, “Pc” in Expression 8 is “in-cylinder pressure at the time of execution of fuel injection (hereinafter referred to as“ in-cylinder pressure during injection ”)”. The in-cylinder pressure at the time of injection is obtained from the output value of the in-cylinder pressure sensor 29, for example. Further, “Fxd” in Expression 8 is a function adapted so that the final new deposit amount can be accurately calculated using the temporary deposit new deposit amount and the in-cylinder pressure during injection as parameters. As shown in Expression 8, the final new deposit amount Xd is calculated as a function of the temporary new deposit amount PXd and the in-cylinder pressure Pc during injection. In other words, the final new deposit amount Xd is calculated by correcting the new temporary deposit amount PXd with the cylinder pressure Pc at the time of injection. It should be noted that the final new deposit amount calculated in accordance with Expression 8 is larger as the provisional deposit new deposit amount is larger, and is smaller as the minimum in-cylinder pressure is lower.

  In the second embodiment, the current total deposit accumulation amount TXd is calculated according to the following equation 9.

  TXd = TXd + Xd (9)

  It should be noted that “TXd” on the left side of Equation 9 is the total deposit accumulation amount calculated this time according to Equation 9. Also, “TXd” on the right side of Equation 9 is the total deposit accumulation amount calculated last time according to Equation 9. Further, “Xd” in Expression 9 is the deposit new deposition amount calculated this time according to Expression 8. As shown in Expression 9, the total deposit accumulation amount TXd is calculated by integrating the new deposit accumulation amount Xd.

  According to the second embodiment, the deposit accumulation amount can be accurately estimated. That is, as described in relation to the first embodiment, the inventor's research has revealed that the in-cylinder pressure during injection affects the deposit peeling amount. Therefore, if the deposit accumulation amount is to be estimated more accurately, the influence of the in-cylinder pressure during injection on the deposit peeling amount should be considered in the estimation of the deposit accumulation amount. In the second embodiment, since the in-cylinder pressure at the time of injection is considered in the estimation of the deposit accumulation amount, the deposit accumulation amount can be accurately estimated according to the second embodiment.

  In the second embodiment, a total deposit accumulation amount that is the amount of deposits accumulated on the wall surface of the nozzle hole is estimated. However, the idea of the present invention included in the second embodiment can also be applied when estimating the thickness of deposits deposited on the nozzle hole wall surface.

  In the second embodiment, the new deposit amount peeled from the wall near the nozzle hole outlet, the wall defining the nozzle hole, and the wall near the nozzle hole inlet is estimated, and the new temporary deposit amount deposited on these wall surfaces The final new deposit amount and the total deposit amount are estimated. However, the idea of the present invention included in the second embodiment is to estimate a new deposit separation amount that peels from any one of the wall surface near the nozzle hole outlet, the wall surface defining the nozzle hole, and the wall surface near the nozzle hole inlet. And it is applicable also when estimating the temporary deposit new deposit amount deposited on the one wall surface, the final new deposit deposit amount, and the total deposit deposit amount.

  In addition, since “metal concentration in fuel” is included as a parameter in Equation 6 used to calculate the new amount of combustion products generated, all the deposits deposited on the wall surface of the nozzle hole in the second embodiment Or it turns out that it is embodiment presupposed that most are comprised from the metal origin product. However, instead of Equation 6, a new amount of combustion product is calculated when it is assumed that all or most of the deposits deposited on the wall surface of the nozzle hole are composed of combustion products other than metal-derived products. Formula may be used, and the amount of new product of combustion product is calculated on the assumption that the deposit deposited on the wall of the nozzle hole is composed of metal-derived products and other combustion products An equation for doing so may be used.

  Further, by continuously accumulating the new deposit amount, the total deposit amount at that time can be calculated. However, there is a limit to the amount of deposit that can be deposited on the wall surface of the nozzle hole. The limit value of the amount of deposit that can be deposited on the wall surface of the nozzle hole (hereinafter, this limit value is referred to as “saturated deposit accumulation amount”) depends on the fuel injection pressure. More specifically, the higher the fuel injection pressure, the smaller the saturated deposit accumulation amount. Therefore, in the second embodiment, every time the total deposit accumulation amount is calculated, a saturated deposit accumulation amount corresponding to the fuel injection pressure is calculated. When the calculated total deposit accumulation amount is equal to or greater than the saturated deposit accumulation amount, the total deposit accumulation is calculated. The amount may be limited to a saturated deposit accumulation amount.

  Next, a routine for calculating the total deposit accumulation amount according to the second embodiment will be described. An example of this routine is shown in FIG. This routine is executed every one engine cycle.

  When the routine of FIG. 4 is started, in step 200, the fuel injection pressure Pin, the nozzle hole temperature Tn, the metal component concentration Cm, and the in-cylinder pressure Pc during injection are acquired. Next, at step 201, a saturated deposit accumulation amount TXdmax is calculated based on the fuel injection pressure Pin acquired at step 200. Next, in step 202, the injection hole temperature Tn and the metal component concentration Cm acquired in step 200 are applied to the above equation 6 to calculate the new combustion product generation amount Xp and the fuel acquired in step 200. The deposit new peel amount Xr is calculated by applying the injection pressure Pin to the above equation 5. Next, in step 202A, the temporary new deposit amount PXd is calculated by applying the new combustion product generation amount Xp and the new deposit separation amount Xr calculated in step 202 to the above equation 7. Next, in step 203, the final new deposit amount Xd is calculated by applying the temporary deposit new deposit amount PXd calculated in step 202A and the in-cylinder in-cylinder pressure Pc acquired in step 200 to the above equation 8. The Next, at step 204, the total new deposit amount TXd is calculated by applying the new deposit amount Xd calculated at step 203 to the above equation 9.

  Next, at step 205, it is determined whether or not the total deposit accumulation amount TXd calculated at step 204 is smaller than the saturated deposit accumulation amount TXdmax calculated at step 201 (TXd <TXdmax). Here, when it is determined that TXd <TXdmax, the routine proceeds to step 206. On the other hand, when it is determined that TXd ≧ TXdmax, the routine proceeds to step 207.

  When the routine proceeds to step 206, the total deposit accumulation amount TXd calculated at step 204 is set as the current total deposit accumulation amount as it is, and the routine is terminated.

  On the other hand, when the routine proceeds to step 207, the saturated deposit accumulation amount TXdmax calculated at step 201 is set as the current total deposit accumulation amount, and the routine is terminated.

  By the way, in the internal combustion engine described above, only a fuel injection mode for executing fuel injection near the compression top dead center during one engine cycle is prepared. However, in the internal combustion engine described above, a plurality of fuel injection modes are prepared, and any one fuel injection mode is selected according to the engine operating state (that is, the operating state of the internal combustion engine). According to the fuel injection may be performed. More specifically, for example, in the above-described internal combustion engine, eight fuel injection modes of the first fuel injection mode to the eighth fuel injection mode are prepared, and any one fuel injection mode is selected according to the engine operating state. The fuel injection may be executed according to the selected fuel injection mode.

  Here, the first fuel injection mode is a fuel injection that is executed in the vicinity of the compression top dead center during one engine cycle (that is, a period during which the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke are performed in the combustion chamber). This is a fuel injection mode in which only (hereinafter, this fuel injection is referred to as “main injection”). This main injection is performed mainly to inject fuel for outputting torque from the internal combustion engine. In the second fuel injection mode, in addition to the main injection during one engine cycle, fuel injection executed in the compression stroke before the main injection (hereinafter, this fuel injection is referred to as “pilot injection”) is performed once. This is the fuel injection mode. This pilot injection is executed mainly to inject fuel for improving the combustibility of the fuel injected by the main injection. The third fuel injection mode is a fuel injection mode in which pilot injection is performed twice in addition to main injection during one engine cycle.

  Further, in the fourth fuel injection mode, pilot injection is performed twice in addition to the main injection during one engine cycle, and fuel injection executed in the expansion stroke after the main injection (hereinafter, this fuel injection is referred to as “after injection”). ”) Is a fuel injection mode that is performed once. This after-injection is performed mainly to inject fuel for burning fine particles generated in the combustion chamber. In the fifth fuel injection mode, in addition to the main injection during one engine cycle, fuel injection executed in the exhaust stroke after the main injection (hereinafter, this fuel injection is referred to as “post injection”) is performed once. This is the fuel injection mode. This post-injection is performed mainly to inject fuel supplied to the exhaust passage through the combustion chamber. The sixth fuel injection mode is a fuel injection mode in which pilot injection is performed once and post injection is performed once in addition to main injection during one engine cycle. The seventh fuel injection mode is a fuel injection mode in which pilot injection is performed twice and post-injection is performed once in addition to main injection during one engine cycle. The eighth fuel injection mode is a fuel injection mode in which pilot injection is performed twice in addition to main injection during one engine cycle, and after-injection and post-injection are each performed once. The fuel supplied to the exhaust passage by the post injection is supplied to, for example, an exhaust gas purifying catalyst disposed in the exhaust passage, burns in the catalyst, and this combustion raises the temperature of the catalyst. Used for.

  Next, an embodiment of a deposit separation amount estimation device and a deposit accumulation amount estimation device of the present invention applied to an internal combustion engine having a plurality of fuel injection modes will be described. In this embodiment (hereinafter referred to as “third embodiment”), the execution timing of fuel injection with the lowest in-cylinder pressure at the time of execution of each fuel injection performed in one engine cycle (hereinafter this timing is referred to as “minimum in-cylinder pressure injection timing”). ") Is acquired.

  That is, when the first fuel injection mode (that is, the fuel injection mode in which only the main injection is performed) is selected as the fuel injection mode, only the main injection is performed. Acquired as in-cylinder pressure injection timing. When the second fuel injection mode (that is, the fuel injection mode in which pilot injection is performed once in addition to the main injection) is selected as the fuel injection mode, the pilot pressure is higher than the in-cylinder pressure at the execution timing of the main injection. Since the in-cylinder pressure at the execution timing of injection is lower, the execution timing of pilot injection is acquired as the minimum in-cylinder pressure injection timing. When the third fuel injection mode (that is, the fuel injection mode in which pilot injection is performed twice in addition to the main injection) is selected as the fuel injection mode, the first pilot among all the fuel injections Since the in-cylinder pressure at the injection execution timing is the lowest, the execution timing of the first pilot injection is acquired as the minimum in-cylinder pressure injection timing. In addition, when the fourth fuel injection mode is selected as the fuel injection mode (that is, the fuel injection mode in which pilot injection is performed twice and after-injection is performed once in addition to main injection), all fuels are selected. Since the in-cylinder pressure at the execution timing of the first pilot injection is the lowest among the injections, the execution timing of the first pilot injection is acquired as the minimum in-cylinder pressure injection timing.

  Further, when the fifth fuel injection mode (that is, the fuel injection mode in which the post injection is performed once in addition to the main injection) is selected as the fuel injection mode, or the sixth fuel injection mode (that is, the fuel injection mode). When the fuel injection mode in which the pilot injection is performed once and the post injection is performed once in addition to the main injection is selected, or the seventh fuel injection mode (that is, in addition to the main injection) is selected. Fuel injection mode in which pilot injection is performed twice and post-injection is performed once), or eighth fuel injection mode as a fuel injection mode (that is, pilot injection is performed twice in addition to main injection and after injection) And a fuel injection mode in which post-injection is performed once each) is selected, Since cylinder pressure in the execution timing of the post injection lowest among the fuel injection Te, execution timing of the post injection is obtained as the minimum cylinder pressure injection timing.

  Then, the volume of the combustion chamber at the lowest cylinder pressure injection timing (hereinafter, this volume is referred to as “the cylinder volume at the time of the lowest cylinder pressure”) is calculated. Then, the in-cylinder pressure at the minimum in-cylinder pressure injection timing (hereinafter, this in-cylinder pressure is referred to as “minimum injection in-cylinder pressure”) Pcmim is calculated according to the following equation 1.

  Pcmim = Fp (Pim, V (θmim), Vivc, n) (10)

  Note that “Pim” in Expression 10 is “pressure of air taken into the combustion chamber from the intake port (so-called intake pressure)”. Further, “V (θmim)” in Expression 10 is “the in-cylinder volume at the time of the minimum in-cylinder pressure”. In addition, “Vivc” in Expression 10 is “in-cylinder volume at compression bottom dead center”. Further, “n” in Expression 10 is “a polytropic index relating to compression / expansion of gas in the combustion chamber”. “Fp” in Equation 10 is a minimum injection using the intake pressure, the in-cylinder volume at the time of the lowest in-cylinder pressure, the in-cylinder volume at the compression bottom dead center, and the polytropic index related to the compression / expansion of gas in the combustion chamber as parameters. This is a function adapted to accurately calculate the hour cylinder pressure Pcmim. As shown in Expression 10, the in-cylinder pressure Pcmim at the time of the minimum injection is calculated from the following: the intake pressure Pim, the in-cylinder volume V (θmim) at the time of the minimum in-cylinder pressure, the in-cylinder volume Vivc at the compression bottom dead center, and the polytropic index n. Calculated with a function. The in-cylinder pressure at the time of the minimum injection calculated according to Expression 10 is higher as the intake pressure is higher, the higher the in-cylinder volume at the time of the lowest in-cylinder pressure, and the higher the in-cylinder volume at the compression bottom dead center, The higher the index, the higher.

  Then, a deposit peeling amount (hereinafter, this deposit peeling amount is referred to as “a new deposit peeling amount”) Xr during a predetermined period (that is, a predetermined period) is calculated according to the following equation 11. The predetermined period is not particularly limited, and may be set arbitrarily. For example, the predetermined period is a period of the one engine cycle.

  Xr = Fxr (Pin, Pcmim) (11)

  “Pin” in Expression 11 is “a fuel injection pressure during fuel injection performed at the lowest in-cylinder pressure injection timing” (hereinafter simply referred to as “fuel injection pressure”). The fuel injection pressure is obtained from the output value of the pressure sensor 26, for example. “Pcmim” in Expression 11 is “minimum in-cylinder pressure during injection” calculated according to Expression 10. Further, “Fxr” in Expression 11 is a function adapted so that the new deposit separation amount can be accurately calculated using the fuel injection pressure and the in-cylinder pressure at the minimum injection as parameters. As shown in Equation 11, the new deposit separation amount Xr is calculated as a function of the fuel injection pressure Pin and the lowest injection cylinder pressure Pcmim. Note that the deposit new peel amount calculated according to Equation 11 increases as the fuel injection pressure increases and increases as the minimum injection cylinder pressure decreases.

  By the way, in the third embodiment, the production amount of the combustion product during the predetermined period (hereinafter, this production amount is referred to as “new combustion product production amount”) Xp is calculated according to the following equation 12.

  Xp = Cm × a × Tn (12)

  “Cm” in Expression 12 is “concentration of metal component in fuel (hereinafter simply referred to as“ metal component concentration ”). This metal component concentration may be, for example, a concentration measured in advance or a concentration measured as appropriate during engine operation. Further, “Tn” in Expression 12 is “a nozzle hole temperature at a specific time point in the predetermined period (hereinafter simply referred to as“ hole nozzle temperature ”)”. The nozzle hole temperature is obtained, for example, from the output value of the temperature sensor 28 at a specific point in time during the predetermined period. Of course, instead of the nozzle hole temperature at a specific point in time during the predetermined period, the average nozzle hole temperature during the predetermined period may be used. In addition, “Tn” in Expression 12 is not limited to the nozzle hole temperature, and may be, for example, the temperature of the atmosphere near the outlet of the fuel injection hole of the fuel injection valve at a specific point in time during the predetermined period. It may be the temperature of the atmosphere in the vicinity of the inlet of the fuel injection hole of the fuel injection valve at a specific point in time. Of course, any temperature other than these temperatures may be used as long as it affects the amount of new combustion products generated. Further, “a” in Expression 12 is a coefficient adapted so that a new amount of combustion product generated related to the metal component concentration Cm and the nozzle hole temperature Tn can be accurately calculated. As shown in Expression 12, the new combustion product generation amount Xp is calculated based on the product of the metal component concentration Cm and the nozzle hole temperature Tn. In other words, the new combustion product generation amount Xp is calculated as a function of the metal component concentration Cm and the nozzle hole temperature Tn. The new combustion product generation amount Xp calculated according to Equation 12 increases as the metal component concentration Cm increases and increases as the nozzle hole temperature Tn increases.

  In the third embodiment, the deposit amount during the predetermined period (hereinafter, this deposit amount is referred to as “deposit new deposit amount”) Xd is calculated according to the following equation (13).

  Xd = Xp-Xr (13)

  Note that “Xp” in Equation 13 is a new amount of combustion product calculated according to Equation 12. Further, “Xr” in Expression 13 is a deposit new peel amount calculated according to Expression 11. As shown in Expression 13, the new deposit amount Xd is calculated by subtracting the new deposit amount Xr from the new combustion product generation amount Xp.

  In the third embodiment, the current total deposit accumulation amount TXd is calculated according to the following equation (14).

  TXd = TXd + Xd (14)

  Note that “TXd” on the left side of Equation 14 is the total deposit accumulation amount calculated this time according to Equation 14. Further, “TXd” on the right side of Expression 14 is the total deposit accumulation amount calculated last time according to Expression 14. Further, “Xd” in Expression 14 is the deposit new accumulation amount calculated this time according to Expression 13. As shown in Equation 14, the total deposit accumulation amount TXd is calculated by integrating the new deposit accumulation amount Xd.

  According to the third embodiment, it is possible to accurately estimate the deposit peeling amount and the deposit accumulation amount for the same reason as described in relation to the first embodiment.

  Furthermore, according to the third embodiment, it is possible to accurately estimate the deposit separation amount and the deposit accumulation amount even when fuel injection is executed a plurality of times during one engine cycle. That is, when fuel injection is executed a plurality of times during one engine cycle, the in-cylinder pressure at the time when each fuel injection is executed may differ for each fuel injection. In this case, the fuel injection executed at the time when the in-cylinder pressure is the lowest among these fuel injections determines the deposit peeling amount during the predetermined period. That is, if the in-cylinder pressure is high, the amount of deposit peeling is small, and conversely, if the in-cylinder pressure is low, the amount of deposit peeling is large. Therefore, even if the deposit is separated from the nozzle hole wall surface by the fuel injection executed before the time when the in-cylinder pressure is the lowest, the fuel injection executed when the cylinder pressure is the lowest further causes the deposit to be further removed from the nozzle hole wall surface. It is peeled off. In this case, the fuel injection executed when the in-cylinder pressure is the lowest determines the deposit separation amount. Further, even if fuel injection is executed after the time when the in-cylinder pressure is lowest, the deposit that can be peeled off by the fuel injection is peeled off by the fuel injection executed when the in-cylinder pressure is lowest. Deposits are not further peeled off from the wall surface of the nozzle hole by the fuel injection executed after the time when the internal pressure is the lowest. Also in this case, the fuel injection executed at the time when the in-cylinder pressure is the lowest determines the deposit peeling amount. In the third embodiment, the in-cylinder pressure at the time when the fuel injection that determines the deposit peeling amount during the predetermined period is executed is used for calculating the deposit peeling amount during the predetermined period, or the deposit peeling during the predetermined period. The deposit peeling amount during a predetermined period calculated using the in-cylinder pressure at the time when the fuel injection that determines the amount is executed is used for calculating the deposit accumulation amount. Therefore, according to the third embodiment, it is possible to accurately estimate the deposit peeling amount and the deposit accumulation amount even when fuel injection is executed a plurality of times during one engine cycle.

  In the third embodiment, a total deposit accumulation amount that is the amount of deposits accumulated on the wall surface of the nozzle hole is estimated. However, the idea of the present invention included in the third embodiment can also be applied when estimating the thickness of deposits deposited on the nozzle hole wall surface.

  Further, in the third embodiment, the new deposit amount peeled from the wall near the nozzle hole outlet, the wall defining the nozzle hole, and the wall near the nozzle hole inlet is estimated, and the new deposit amount deposited on these wall surfaces and Total deposit accumulation is estimated. However, the idea of the present invention included in the third embodiment is to estimate a new deposit separation amount that peels from any one of the wall surface near the nozzle hole outlet, the wall surface defining the nozzle hole, and the wall surface near the nozzle hole inlet. And it is applicable also when estimating the deposit new deposit amount and total deposit deposit amount deposited on the said one wall surface.

  In addition, since “metal concentration in fuel” is included as a parameter in Equation 12 used to calculate the new amount of combustion product, all the deposits deposited on the wall surface of the nozzle hole in the third embodiment Or it turns out that it is embodiment presupposed that most are comprised from the metal origin product. However, instead of Equation 12, a new combustion product generation amount is calculated on the assumption that all or most of the deposits deposited on the wall surface of the nozzle hole are composed of combustion products other than the metal-derived product. Formula may be used, and the amount of new product of combustion product is calculated on the assumption that the deposit deposited on the wall of the nozzle hole is composed of metal-derived products and other combustion products An equation for doing so may be used.

  The fuel injection pressure (that is, the pressure of the fuel injected from the fuel injection hole of the fuel injection valve) is compared with the case where all or most of the deposit deposited on the wall surface of the injection hole is made of a metal-derived product. Is the case. In other words, the combustion products that are conventionally recognized as deposits deposited on the wall surface of the nozzle hole are different from the metal-derived products (for example, lower carboxylates such as zinc, calcium, magnesium, carbonates, oxalates, etc.). If the fuel injection pressure is a relatively high pressure within the practical range, the deposit made of the combustion product is separated from the wall surface of the injection hole by the fuel flowing in the fuel injection hole. However, deposits made of metal-derived products are not easily separated from the wall surface of the nozzle hole by the fuel flowing through the fuel injection hole even if the fuel injection pressure is relatively high within the practical range. For this reason, the case where all or most of the deposit deposited on the wall surface of the nozzle hole is made of a metal-derived product is a case where the fuel injection hole is relatively high.

  Further, by continuously accumulating the new deposit amount, the total deposit amount at that time can be calculated. However, there is a limit to the amount of deposit that can be deposited on the wall surface of the nozzle hole. The limit value of the amount of deposit that can be deposited on the wall surface of the nozzle hole (hereinafter, this limit value is referred to as “saturated deposit accumulation amount”) depends on the fuel injection pressure. More specifically, the higher the fuel injection pressure, the smaller the saturated deposit accumulation amount. Therefore, in the third embodiment, every time the total deposit accumulation amount is calculated, the saturated deposit accumulation amount corresponding to the fuel injection pressure is calculated. When the calculated total deposit accumulation amount is equal to or greater than the saturated deposit accumulation amount, the total deposit accumulation is calculated. The amount may be limited to a saturated deposit accumulation amount.

  Next, a routine for performing calculation of the total deposit accumulation amount according to the third embodiment will be described. An example of this routine is shown in FIG. This routine is executed every one engine cycle.

  When the routine of FIG. 5 is started, in step 300, the fuel injection pressure Pin, the injection hole temperature Tn, the metal component concentration Cm, the intake pressure Pim, and the in-cylinder volume Vivc at the compression bottom dead center are acquired. Next, at step 301, the saturated deposit accumulation amount TXdmax is calculated based on the fuel injection pressure Pin acquired at step 300. Next, at step 302, it is determined whether or not the current fuel injection mode is any one of the fifth fuel injection mode to the eighth fuel injection mode (Mode = Post). That is, it is determined whether or not the current fuel injection mode is a fuel injection mode in which at least post injection is performed. Here, when it is determined that Mode = Post, the routine proceeds to step 303. On the other hand, when it is determined that Mode ≠ Post, the routine proceeds to Step 308.

  When it is determined in step 302 that Mode = Post and the routine proceeds to step 303, the minimum in-cylinder pressure injection timing θmim is acquired. When the routine proceeds to step 303, at least the fuel injection mode in which the post injection is performed is selected. Therefore, the execution timing of the post injection is acquired as the minimum in-cylinder pressure injection timing θmim. Next, in step 304, the in-cylinder volume V (θmim) at the time of the minimum in-cylinder pressure is calculated based on the minimum in-cylinder pressure injection timing θmim acquired in step 303. Next, at step 305, the intake pressure Pim acquired at step 300 and the in-cylinder volume Vivc at the compression bottom dead center, the in-cylinder volume V (θmim) at the time of the lowest in-cylinder pressure calculated at step 304, and the polytropic index n Is applied to the above equation 10 to calculate the minimum injection cylinder pressure Pcmim. Next, in step 306, the injection hole temperature Tn and the metal component concentration Cm acquired in step 300 are applied to the above equation 12 to calculate the new combustion product generation amount Xp, and the fuel acquired in step 300 The deposit new peel amount Xr is calculated by applying the injection pressure Pin and the in-cylinder in-cylinder pressure Pcmim calculated in step 305 to the above equation 11. Next, in step 307, the new deposit amount Xd and the new deposit amount Xr calculated in step 306 are applied to the above equation 13 to calculate the new deposit amount Xd, and the routine proceeds to step 313.

  On the other hand, when it is determined in step 302 that Mode ≠ Post and the routine proceeds to step 308, the minimum in-cylinder pressure injection timing θmim is acquired. When the routine proceeds to step 308, at least a fuel injection mode other than the fuel injection mode in which the post injection is performed is selected. When the first fuel injection mode is selected, the minimum in-cylinder pressure injection timing θmim is set as the main injection mode. When the execution timing is acquired and the second fuel injection mode is selected, the execution timing of pilot injection is acquired as the minimum in-cylinder pressure injection timing θmim, and when the third fuel injection mode is selected, the minimum cylinder The execution timing of the first pilot injection is acquired as the internal pressure injection timing θmim, and when the fourth fuel injection mode is selected, the execution timing of the first pilot injection is acquired as the minimum in-cylinder pressure injection timing θmim. Next, in step 309, the in-cylinder volume V (θmim) at the time of the minimum in-cylinder pressure is calculated based on the minimum in-cylinder pressure injection timing θmim acquired in step 308. Next, at step 310, the intake pressure Pim acquired at step 300 and the in-cylinder volume Vivc at the compression bottom dead center, the in-cylinder volume V (θmim) at the time of the lowest in-cylinder pressure calculated at step 309, and the polytropic index n Is applied to the above equation 10 to calculate the minimum injection cylinder pressure Pcmim. Next, in step 311, the new combustion product generation amount Xp is calculated by applying the nozzle hole temperature Tn and metal component concentration Cm acquired in step 300 to the above equation 12, and the fuel acquired in step 300 The deposit new peel amount Xr is calculated by applying the injection pressure Pin and the in-cylinder pressure Pcmim at the time of injection calculated in step 310 to the above equation 11. Next, in step 312, the new deposit amount Xd and the new deposit amount Xr calculated in step 311 are applied to the above equation 13 to calculate the new deposit amount Xd, and the routine proceeds to step 313.

  When the routine proceeds from step 307 to step 313, the total new deposit amount TXd is calculated by applying the new deposit amount Xd calculated in step 307 to the above equation 14. On the other hand, when the routine proceeds from step 312 to step 313, the total new deposit amount TXd is calculated by applying the new deposit amount Xd calculated in step 312 to the above equation 14.

  Next, at step 314, it is determined whether or not the total deposit accumulation amount TXd calculated at step 313 is smaller than the saturated deposit accumulation amount TXdmax calculated at step 301 (TXd <TXdmax). Here, when it is determined that TXd <TXdmax, the routine proceeds to step 315. On the other hand, when it is determined that TXd ≧ TXdmax, the routine proceeds to step 316.

  When the routine proceeds to step 315, the total deposit accumulation amount TXd calculated in step 313 is set as the current total deposit accumulation amount as it is, and the routine ends.

  On the other hand, when the routine proceeds to step 316, the saturated deposit accumulation amount TXdmax calculated at step 301 is set as the current total deposit accumulation amount, and the routine is terminated.

  Next, a fourth embodiment will be described. In the fourth embodiment, the execution timing of fuel injection with the lowest in-cylinder pressure (that is, the pressure in the combustion chamber) at the time of execution of each fuel injection performed during the one engine cycle (hereinafter, this timing is referred to as “minimum in-cylinder pressure injection timing”). ") Is acquired.

  That is, when the first fuel injection mode (that is, the fuel injection mode in which only main injection is performed) is selected as the fuel injection mode, the execution timing of main injection is acquired as the minimum in-cylinder pressure injection timing. When the second fuel injection mode (that is, the fuel injection mode in which the pilot injection is performed once in addition to the main injection) is selected as the fuel injection mode, the execution timing of the pilot injection is the lowest in-cylinder pressure injection timing. Get as. When the third fuel injection mode (that is, the fuel injection mode in which pilot injection is performed twice in addition to main injection) is selected, the execution timing of the first pilot injection is set as the minimum in-cylinder pressure injection timing. To be acquired. When the fourth fuel injection mode (that is, the fuel injection mode in which pilot injection is performed twice and after-injection is performed once in addition to main injection) is selected, the first pilot injection is executed. The timing is acquired as the minimum in-cylinder pressure injection timing.

  Further, when the fifth fuel injection mode (that is, the fuel injection mode in which the post injection is performed once in addition to the main injection) is selected as the fuel injection mode, or the sixth fuel injection mode (that is, the fuel injection mode). When the fuel injection mode in which the pilot injection is performed once and the post injection is performed once in addition to the main injection is selected, or the seventh fuel injection mode (that is, in addition to the main injection) is selected. Fuel injection mode in which pilot injection is performed twice and post-injection is performed once), or eighth fuel injection mode as a fuel injection mode (that is, pilot injection is performed twice in addition to main injection and after injection) And a fuel injection mode in which post-injection is performed once each) is selected, Execution timing of strike injection is obtained as a minimum cylinder pressure injection timing.

  Then, the volume of the combustion chamber at the lowest cylinder pressure injection timing (hereinafter, this volume is referred to as “the cylinder volume at the time of the lowest cylinder pressure”) is calculated.

  Then, in-cylinder pressure at the minimum in-cylinder pressure injection timing (hereinafter, this in-cylinder pressure is referred to as “minimum injection in-cylinder pressure”) Pcmim is calculated according to the following equation 15.

  Pcmim = Fp (Pim, V (θmim), Vivc, n) (15)

  Note that “Pim” in Expression 15 is “pressure of air taken into the combustion chamber from the intake port (so-called intake pressure)”. Further, “V (θmim)” in Expression 15 is “the in-cylinder volume at the time of the minimum in-cylinder pressure”. In addition, “Vivc” in Expression 15 is “in-cylinder volume at compression bottom dead center”. Further, “n” in Expression 15 is “polytropic index related to compression / expansion of gas in the combustion chamber”. Further, “Fp” in Expression 15 is a minimum injection using the intake pressure, the in-cylinder volume at the time of the minimum in-cylinder pressure, the in-cylinder volume at the compression bottom dead center, and the polytropic index related to the compression / expansion of the gas in the combustion chamber as parameters. This is a function adapted to accurately calculate the hour cylinder pressure Pcmim. As shown in Equation 15, the in-cylinder pressure Pcmim at the time of the minimum injection is obtained by calculating the in-cylinder volume V (θmim) at the time of the intake pressure Pim, the minimum in-cylinder pressure, the in-cylinder volume Vivc at the compression bottom dead center, and the polytropic index n. Calculated with a function. Note that the minimum in-cylinder pressure at the time of injection calculated according to Equation 15 is higher as the intake pressure is higher, higher as the in-cylinder volume at the time of the lowest in-cylinder pressure is smaller, and higher as the in-cylinder volume at the compression bottom dead center is larger. The higher the index, the higher.

  Then, a deposit peeling amount (hereinafter, this deposit peeling amount is referred to as a “new deposit peeling amount”) Xr during a predetermined period (that is, a predetermined period) is calculated according to the following equation 16. The predetermined period is not particularly limited, and may be set arbitrarily. For example, the predetermined period is a period of the one engine cycle.

  Xr = b × Pin (16)

  “Pin” in Expression 16 is “a fuel injection pressure during fuel injection performed at the lowest in-cylinder pressure injection timing (hereinafter simply referred to as“ fuel injection pressure ”)”. The fuel injection pressure is obtained from the output value of the pressure sensor 26, for example. Further, “b” in Expression 16 is a coefficient adapted so that the deposit separation amount related to the fuel injection pressure Pin is accurately calculated. As shown in Expression 16, the new deposit separation amount Xr is a deposit separation amount b × Pin that can be grasped in relation to the fuel injection hole Pin. In other words, the deposit new peel amount Xr is calculated as a function of the fuel injection hole Pin. And the deposit new peeling amount Xr calculated according to Formula 16 increases as the fuel injection hole Pin increases.

  In the fourth embodiment, the production amount of the combustion product (that is, the new combustion product production amount) Xp during the predetermined period is calculated according to the following equation 17.

  Xp = Cm × a × Tn (17)

  “Cm” in Expression 17 is “concentration of metal component in fuel (ie, metal component concentration)”. This metal component concentration may be, for example, a concentration measured in advance or a concentration measured as appropriate during engine operation. Further, “Tn” in Expression 17 is “a nozzle hole temperature at a specific time point in the predetermined period (hereinafter simply referred to as“ hole nozzle temperature ”)”. The nozzle hole temperature is obtained, for example, from the output value of the temperature sensor 28 at a specific point in time during the predetermined period. Of course, instead of the nozzle hole temperature at a specific point in time during the predetermined period, the average nozzle hole temperature during the predetermined period may be used. Further, “Tn” in Expression 17 is not limited to this nozzle hole temperature, and may be, for example, the temperature of the atmosphere near the outlet of the fuel injection hole of the fuel injection valve at a specific point in time during the predetermined period. It may be the temperature of the atmosphere in the vicinity of the inlet of the fuel injection hole of the fuel injection valve at a specific point in time. Of course, any temperature other than these temperatures may be used as long as it affects the amount of new combustion products generated. Further, “a” in Expression 17 is a coefficient adapted to accurately calculate the new amount of combustion product generated related to the metal component concentration Cm and the nozzle hole temperature Tn. As shown in Equation 17, the new combustion product generation amount Xp is calculated based on the product of the metal component concentration Cm and the nozzle hole temperature Tn. In other words, the new combustion product generation amount Xp is calculated as a function of the metal component concentration Cm and the nozzle hole temperature Tn. The new combustion product generation amount Xp calculated according to Equation 17 increases as the metal component concentration Cm increases and increases as the nozzle hole temperature Tn increases.

  In the fourth embodiment, the deposit accumulation amount (that is, the temporary deposit new accumulation amount) PXd during the predetermined period is calculated according to the following equation 18.

  PXd = Xp−Xr (18)

  In addition, “Xp” in Expression 18 is a new combustion product generation amount calculated according to Expression 17. Further, “Xr” in Expression 18 is a deposit new peel amount calculated according to Expression 16. As shown in Equation 18, the temporary deposit new deposition amount PXd is calculated by subtracting the new deposit deposit amount Xr from the new combustion product generation amount Xp.

  In the fourth embodiment, the final new deposit amount Xd is calculated according to the following equation 19.

  Xd = Fxd (PXd, Pcmim) (19)

  Note that “PXd” in Expression 19 is a temporary deposit new deposition amount calculated according to Expression 9. Further, “Pcmim” in Expression 19 is “minimum injection cylinder pressure” calculated according to Expression 15. Further, “Fxd” in Expression 19 is a function adapted so that the final new deposit amount can be accurately calculated using the provisional deposit new deposit amount and the cylinder pressure at the time of minimum injection as parameters. As shown in Expression 19, the final new deposit amount Xd is calculated as a function of the temporary new deposit amount PXd and the minimum injection cylinder pressure Pcmim. In other words, the final new deposit amount Xd is calculated by correcting the new temporary deposit amount PXd by the minimum injection cylinder pressure Pcmim. It should be noted that the final new deposit amount calculated in accordance with Equation 19 is larger as the provisional deposit new deposit amount is larger, and is smaller as the minimum injection cylinder pressure is lower.

  In the fourth embodiment, the current total deposit accumulation amount TXd is calculated according to the following equation 20.

  TXd = TXd + Xd (20)

  It should be noted that “TXd” on the left side of Equation 20 is the total deposit accumulation amount calculated this time according to Equation 20. Further, “TXd” on the right side of Expression 20 is the total deposit accumulation amount calculated last time according to Expression 20. Further, “Xd” in Expression 20 is the deposit new deposition amount calculated this time according to Expression 19. As shown in Equation 20, the total deposit accumulation amount TXd is calculated by integrating the new deposit accumulation amount Xd.

  According to the fourth embodiment, it is possible to accurately estimate the deposit amount for the same reason as described in relation to the second embodiment.

  Furthermore, according to the fourth embodiment, it is possible to accurately estimate the deposit accumulation amount even when fuel injection is executed a plurality of times during one engine cycle. That is, as described in relation to the third embodiment, the fuel injection executed at the time when the in-cylinder pressure is the lowest determines the deposit peeling amount. In the fourth embodiment, the in-cylinder pressure at the time when the fuel injection that determines the deposit separation amount during the predetermined period is executed is used for correcting the temporary deposit accumulation amount. For this reason, according to the fourth embodiment, the deposit accumulation amount can be accurately estimated even when fuel injection is performed a plurality of times during one engine cycle.

  In the fourth embodiment, a total deposit accumulation amount that is the amount of deposits accumulated on the wall surface of the nozzle hole is estimated. However, the idea of the present invention included in the fourth embodiment is also applicable when estimating the thickness of deposits deposited on the nozzle hole wall surface.

  Further, in the fourth embodiment, the deposit new peel amount peeled from the nozzle hole vicinity wall surface, the nozzle hole defining wall surface, and the nozzle hole inlet near wall surface is estimated, and the provisional deposit new deposit amount deposited on these wall surfaces The final new deposit amount and the total deposit amount are estimated. However, the idea of the present invention included in the fourth embodiment is to estimate the deposit new peel amount peeled from any one of the wall surface near the nozzle hole outlet, the wall surface defining the nozzle hole, and the wall surface near the nozzle hole inlet. And it is applicable also when estimating the temporary deposit new deposit amount deposited on the one wall surface, the final new deposit deposit amount, and the total deposit deposit amount.

  In addition, since “metal concentration in fuel” is included as a parameter in Equation 17 used to calculate the new amount of combustion products generated, all the deposits deposited on the wall surface of the nozzle hole in the fourth embodiment Or it turns out that it is embodiment presupposed that most are comprised from the metal origin product. However, instead of Equation 17, a new combustion product generation amount is calculated on the assumption that all or most of the deposits deposited on the wall surface of the nozzle hole are composed of combustion products other than metal-derived products. Formula may be used, and the amount of new product of combustion product is calculated on the assumption that the deposit deposited on the wall of the nozzle hole is composed of metal-derived products and other combustion products An equation for doing so may be used.

  Further, by continuously accumulating the new deposit amount, the total deposit amount at that time can be calculated. However, there is a limit to the amount of deposit that can be deposited on the wall surface of the nozzle hole. The limit value of the amount of deposit that can be deposited on the wall surface of the nozzle hole (hereinafter, this limit value is referred to as “saturated deposit accumulation amount”) depends on the fuel injection pressure. More specifically, the higher the fuel injection pressure, the smaller the saturated deposit accumulation amount. Therefore, in the fourth embodiment, every time the total deposit accumulation amount is calculated, a saturated deposit accumulation amount corresponding to the fuel injection pressure is calculated. When the calculated total deposit accumulation amount is equal to or greater than the saturated deposit accumulation amount, the total deposit accumulation is calculated. The amount may be limited to a saturated deposit accumulation amount.

  Next, a routine for performing calculation of the total deposit accumulation amount according to the fourth embodiment will be described. An example of this routine is shown in FIG. This routine is executed every one engine cycle.

  When the routine of FIG. 6 is started, in step 400, the fuel injection pressure Pin, the injection hole temperature Tn, the metal component concentration Cm, the intake pressure Pim, and the in-cylinder volume Vivc at the compression bottom dead center are acquired. Next, at step 401, the saturated deposit accumulation amount TXdmax is calculated based on the fuel injection pressure Pin acquired at step 400. Next, at step 402, it is determined whether or not the current fuel injection mode is any one of the fifth fuel injection mode to the eighth fuel injection mode (Mode = Post). That is, it is determined whether or not the current fuel injection mode is a fuel injection mode in which at least post injection is performed. If it is determined that Mode = Post, the routine proceeds to step 403. On the other hand, if it is determined that Mode ≠ Post, the routine proceeds to step 408.

  When it is determined in step 402 that Mode = Post and the routine proceeds to step 403, the minimum in-cylinder pressure injection timing θmim is acquired. When the routine proceeds to step 403, at least the fuel injection mode in which the post injection is performed is selected. Therefore, the execution timing of the post injection is acquired as the minimum in-cylinder pressure injection timing θmim. Next, in step 404, the in-cylinder volume V (θmim) at the time of the minimum in-cylinder pressure is calculated based on the minimum in-cylinder pressure injection timing θmim acquired in step 403. Next, at step 405, the intake pressure Pim acquired at step 400 and the in-cylinder volume Vivc at the compression bottom dead center, the in-cylinder volume V (θmim) at the time of the lowest in-cylinder pressure calculated at step 404, and the polytropic index n Is applied to the above equation 15 to calculate the lowest injection cylinder pressure Pcmim. Next, in step 406, the injection hole temperature Tn and the metal component concentration Cm acquired in step 400 are applied to the above equation 17 to calculate the new combustion product generation amount Xp, and the fuel acquired in step 400. By applying the injection pressure Pin to the above equation 16, a new deposit separation amount Xr is calculated. Next, in step 406A, the temporary new deposit amount PXd is calculated by applying the new combustion product generation amount Xp and the new deposit separation amount Xr calculated in step 406 to the above equation 18. Next, in step 407, the final new deposit amount Xd is calculated by applying the temporary deposit new deposit amount PXd calculated in step 406A and the minimum injection cylinder pressure Pcmim calculated in step 405 to the above equation 19. The routine then proceeds to step 413.

  On the other hand, when it is determined in step 402 that Mode ≠ Post and the routine proceeds to step 408, the minimum in-cylinder pressure injection timing θmim is acquired. When the routine proceeds to step 408, at least a fuel injection mode other than the fuel injection mode in which post injection is performed is selected, and when the first fuel injection mode is selected, the minimum in-cylinder pressure injection timing θmim is set as the main injection mode. When the execution timing is acquired and the second fuel injection mode is selected, the execution timing of pilot injection is acquired as the minimum in-cylinder pressure injection timing θmim, and when the third fuel injection mode is selected, the minimum cylinder The execution timing of the first pilot injection is acquired as the internal pressure injection timing θmim, and when the fourth fuel injection mode is selected, the execution timing of the first pilot injection is acquired as the minimum in-cylinder pressure injection timing θmim. Next, in step 409, the in-cylinder volume V (θmim) at the time of the minimum in-cylinder pressure is calculated based on the minimum in-cylinder pressure injection timing θmim acquired in step 408. Next, at step 410, the intake pressure Pim acquired at step 400 and the in-cylinder volume Vivc at the compression bottom dead center, the in-cylinder volume V (θmim) at the time of the lowest in-cylinder pressure calculated at step 409, and the polytropic index n Is applied to the above equation 15 to calculate the lowest injection cylinder pressure Pcmim. Next, in step 411, the new combustion product generation amount Xp is calculated by applying the nozzle hole temperature Tn and the metal component concentration Cm acquired in step 400 to the above equation 17, and the fuel acquired in step 400 is calculated. By applying the injection pressure Pin to the above equation 16, a new deposit separation amount Xr is calculated. Next, in step 411A, the new temporary deposit amount Xd is calculated by applying the new combustion product generation amount Xp and the new deposit separation amount Xr calculated in step 411 to the above equation 18. Next, in step 412, the final new deposit amount Xd is calculated by applying the provisional deposit new deposit amount PXd calculated in step 411 A and the minimum in-cylinder pressure Pcmim calculated in step 410 to the above equation 19. The routine then proceeds to step 413.

  When the routine proceeds from step 407 to step 413, the total new deposit amount TXd is calculated by applying the new deposit amount Xd calculated in step 407 to the above equation 20. On the other hand, when the routine proceeds from step 412 to step 413, the total new deposit amount TXd is calculated by applying the new deposit amount Xd calculated in step 412 to the above equation 20.

  Next, at step 414, it is determined whether or not the total deposit accumulation amount TXd calculated at step 413 is smaller than the saturated deposit accumulation amount TXdmax calculated at step 401 (TXd <TXdmax). Here, when it is determined that TXd <TXdmax, the routine proceeds to step 415. On the other hand, when it is determined that TXd ≧ TXdmax, the routine proceeds to step 416.

  When the routine proceeds to step 415, the total deposit accumulation amount TXd calculated at step 413 is set as the current total deposit accumulation amount as it is, and the routine is terminated.

  On the other hand, when the routine proceeds to step 416, the saturated deposit accumulation amount TXdmax calculated in step 401 is set as the current total deposit accumulation amount, and the routine is terminated.

  In the above-described embodiment, the fuel injection pressure is used to calculate the deposit new peel amount, but a parameter having a close correlation with the fuel injection pressure may be used instead of the fuel injection pressure.

  Also, if the flow coefficient relating to the fuel flowing through the fuel injection hole of the fuel injection valve is different, the deposit separation amount is different even if the fuel injection pressure is constant. Specifically, the smaller the flow coefficient, the greater the amount of deposit peeling. Therefore, in the above-described embodiment, in addition to considering the in-cylinder in-cylinder pressure or the minimum in-cylinder pressure during the calculation of the new deposit separation amount or the correction of the temporary deposit new accumulation amount, the fuel flows through the fuel injection hole of the fuel injection valve. You may make it consider the flow coefficient (or parameter which has a correlation with the said flow coefficient) regarding the fuel.

  Further, if the deposit thickness deposited on the wall surface of the nozzle hole is different, the amount of deposit peeling is different even if the fuel injection pressure is constant. Specifically, the deposit peeling amount increases as the thickness of the deposit deposited on the wall surface of the nozzle hole increases. Therefore, in the above-described embodiment, in addition to considering the in-cylinder in-cylinder pressure or the minimum in-cylinder in-cylinder pressure for calculating the deposit new peel amount or correcting the temporary deposit new deposit amount, the deposit accumulated on the wall surface of the nozzle hole You may make it consider thickness (or the total deposit accumulation amount which can represent the said thickness).

  In addition, examples of the metal-derived product constituting the deposit include lower carboxylate, carbonate, and oxalate. Among these metal-derived products, carbonate is decomposed when the ambient temperature exceeds a certain temperature. Therefore, in the above-described embodiment, the temperature around the deposit is acquired every time the total deposit accumulation amount is calculated, and the total deposit is obtained when the acquired temperature is equal to or higher than a predetermined temperature (that is, the decomposition temperature of carbonate). The total deposit accumulation amount may be calculated by setting the deposit amount made of carbonate out of the accumulation amount to zero. The predetermined temperature is obtained as a temperature at which the carbonate is decomposed by experiments or the like, and may be any temperature as long as it is a predetermined temperature. For example, the predetermined temperature is approximately 300 ° C.

  Of course, this may be applied to lower carboxylates and oxalates as well. That is, if the temperature at which the lower carboxylate constituting the deposit is decomposed is known in advance, in the above-described embodiment, the temperature around the deposit is obtained and calculated every time the total deposit accumulation amount is calculated. When the deposited temperature is equal to or higher than a predetermined temperature (that is, the decomposition temperature of the lower carboxylate), the total deposit deposition amount is calculated by setting the amount of deposits composed of lower carboxylates out of the total deposit deposition amount to zero. May be. Further, when the acquired temperature is equal to or higher than a predetermined temperature (that is, the decomposition temperature of oxalate), the total deposit accumulation amount is calculated by setting the deposit amount made of oxalate out of the total deposit accumulation amount to zero. It may be.

  Further, the above-described embodiment is an embodiment when the present invention is applied to an internal combustion engine in which a fuel injection valve is arranged so as to directly inject fuel into the combustion chamber. However, the present invention is also applicable to an internal combustion engine in which a fuel injection valve is disposed so as to inject fuel into the intake port.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 22 ... Fuel injection valve, 29 ... In-cylinder pressure sensor, 34 ... Fuel injection hole, Pin ... Fuel injection pressure, Pc ... In-cylinder pressure at injection, Pcmim ... In-cylinder pressure at minimum injection

Claims (5)

  In an internal combustion engine provided with a fuel injection valve, an injection hole defining wall which is a wall defining a fuel injection hole of the fuel injection valve, and a fuel near the inlet of the fuel injection hole which is a wall other than the injection hole defining wall A wall surface of the injection valve, and a wall surface other than the injection hole defining wall surface, and at least deposits deposited on the injection hole wall surface comprising at least one wall surface of the fuel injection valve near the outlet of the fuel injection hole The deposit is calculated by calculating the deposit peeling amount, which is the amount of deposit peeling from the nozzle hole wall surface, using a plurality of parameters representing factors affecting the deposit peeling force, which is a force for peeling a part from the nozzle hole wall surface. A deposit separation amount estimation device for estimating a separation amount, wherein one of the plurality of parameters is a pressure of fuel injected from a fuel injection hole of a fuel injection valve, and the plurality of parameters Another one is the deposit peeling quantity estimation apparatus is a pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve.   In an internal combustion engine provided with a fuel injection valve, an injection hole defining wall which is a wall defining a fuel injection hole of the fuel injection valve, and a fuel near the inlet of the fuel injection hole which is a wall other than the injection hole defining wall The amount of deposits deposited on the wall surface of the injection hole that is composed of at least one of the wall surface of the injection valve and the wall surface of the fuel injection valve in the vicinity of the outlet of the fuel injection hole. A deposit accumulation amount estimation apparatus for estimating a deposit accumulation amount by calculating a deposit accumulation amount, wherein the deposit delamination amount estimation device according to claim 1 is provided, and a generated amount of a deposit constituent material constituting the deposit is a deposit. The deposit peeling amount is estimated by the deposit peeling amount estimation device, and is estimated from the deposit constituent generation amount. Deposit amount estimation device which deposit amount is calculated by subtracting the Hanareryou.   In the case where the deposit peeling amount during a predetermined period is calculated and fuel injection from the fuel injection valve is executed a plurality of times during the predetermined period, each fuel injection during the predetermined period is calculated. The lowest pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve at the time of execution is adopted as the pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve used for calculating the deposit separation amount. The deposit peeling amount estimation apparatus according to claim 1 or the deposit accumulation amount estimation apparatus according to claim 2.   In an internal combustion engine provided with a fuel injection valve, an injection hole defining wall which is a wall defining a fuel injection hole of the fuel injection valve, and a fuel near the inlet of the fuel injection hole which is a wall other than the injection hole defining wall The amount of deposits deposited on the wall surface of the injection hole that is composed of at least one of the wall surface of the injection valve and the wall surface of the fuel injection valve in the vicinity of the outlet of the fuel injection hole. In the deposit accumulation amount estimation device for estimating the deposit accumulation amount by calculating the deposit accumulation amount, the amount of the substance generated as the deposit constituent material constituting the deposit is estimated as the deposit constituent substance generation amount and the jet A deposit peeling amount, which is the amount of deposit peeling from the hole wall surface, is estimated using the pressure of the fuel injected from the fuel injection hole of the fuel injection valve, and the deposit structure. A provisional deposit accumulation amount is calculated by subtracting the deposit peeling amount from the substance generation amount, and the provisional deposit accumulation amount is corrected in consideration of the pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve. This is a deposit accumulation amount estimation device for calculating the final deposit accumulation amount.   In the case where the deposit peeling amount during a predetermined period is calculated and fuel injection from the fuel injection valve is executed a plurality of times during the predetermined period, each fuel injection during the predetermined period is calculated. The lowest pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve at the time of execution is adopted as the pressure of the atmosphere around the outlet of the fuel injection hole of the fuel injection valve used for the correction of the temporary deposit accumulation amount The deposit accumulation amount estimation apparatus according to claim 4.

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