JP2012229627A - 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 peeling amount or a deposit deposition amount in the vicinity of a fuel injection hole.SOLUTION: In an internal combustion engine provided with a fuel injection valve 22, a deposit peeling amount is estimated by calculating the deposit peeling amount 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 of a fuel injection hole 34. At least one parameter of the plurality of parameters is a parameter representing a factor for varying the deposit peeling force, and at least other one parameter of the plurality of parameters is a flow coefficient Cd related to fuel flowing in the fuel injection hole, or a parameter θs, Ls, dQ, or QR having correlation with the flow coefficient.

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 there is a possibility that the expected amount of fuel will not be injected from the fuel injection valve, it is not a little useful to know the amount of combustion products deposited on the wall near the nozzle hole outlet. is there. In Patent Document 1, the amount of combustion products deposited on the wall surface near the nozzle hole outlet (hereinafter, the combustion products deposited on the wall surface near the nozzle hole outlet is also referred to as “deposit”. Patent Document 1 discloses an apparatus for estimating “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.

  Therefore, in the apparatus described in Patent Document 1, each time a predetermined period elapses, the amount of combustion products generated during the predetermined period (hereinafter, this amount is referred to as “combustion product generation amount”), The amount of deposit peeled off from the wall near the nozzle hole outlet during the predetermined period (hereinafter, this amount is referred to as “deposit peeling amount”) is obtained, and the predetermined amount is obtained by subtracting the deposit peeling amount from the amount of combustion products produced. Calculate the amount of combustion products newly deposited on the wall near the nozzle hole outlet during the period (hereinafter this amount is referred to as “new deposit amount”), and integrate this new deposit amount to calculate the total deposit amount. I am trying to calculate.

JP 2006-57538 A JP 2008-231996 A

  By the way, in the apparatus described in Patent Document 1, the amount of fuel injection during the predetermined period (that is, the amount of fuel injected from the fuel injection valve) and the amount of combustion product generated during the predetermined period are considered. Thus, the deposit peeling amount is obtained. However, in order to obtain the deposit peeling amount more accurately and, moreover, to obtain the deposit accumulation amount more accurately, in addition to the fuel injection amount and the amount of combustion product generated in the estimation of the deposit peeling amount or the estimation of the deposit accumulation amount. The study of the inventor of the present application has revealed that elements need to be considered.

  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, at least one of the plurality of parameters is a parameter representing a factor that fluctuates the deposit peeling force, and at least one of the plurality of parameters relates to a fuel that flows in a fuel injection hole of a fuel injection valve. A flow coefficient or a parameter correlated with the flow coefficient.

  According to the present invention, the deposit peeling amount can be accurately estimated. That is, the parameter (for example, fuel injection pressure etc.) which shows the factor which fluctuates deposit peeling force as a factor which influences the deposit peeling amount is mentioned. That is, if this parameter varies, the deposit peeling amount also varies. However, even if this parameter is constant, the deposit peeling amount varies depending on the shape of the wall surface of the nozzle hole. That is, the shearing action applied to the deposit from the fuel flowing around the deposit differs depending on the shape of the wall surface of the nozzle hole. If the strength of this shearing action is large, the amount of deposit peeling from the wall surface of the nozzle hole increases. Furthermore, the occurrence of cavitation around the deposit varies depending on the shape of the wall surface of the nozzle hole. If the erosion strength in the cavitation is large, the amount of deposit peeling from the wall surface of the nozzle hole increases. Therefore, in order to estimate the deposit peeling amount more accurately, the influence of the shape of the nozzle hole wall surface on the deposit peeling amount should be considered. Here, the research of the inventor of the present application revealed that the flow coefficient is a parameter that represents the influence of the shape of the wall surface of the nozzle hole on the deposit peeling amount. That is, the smaller the flow coefficient, the greater the strength of the shearing action given to the deposit from the fuel flowing around the deposit, and the greater the amount of deposit peeling from the wall surface of the nozzle hole. Further, the smaller the flow coefficient, the greater the erosion strength in the cavitation around the deposit, and therefore the greater the amount of deposit peeling from the wall surface of the nozzle hole. Then, paying attention to the fact that there is a very close correlation between the influence of the shape of the nozzle hole wall surface on the deposit peeling amount from the nozzle hole wall surface and the influence of the flow coefficient on the deposit peeling amount, the present invention In this case, the deposit separation amount is calculated using a flow coefficient relating to the fuel flowing through the fuel injection hole or a parameter having a correlation with the flow coefficient. As described above, in the present invention, the deposit separation amount is calculated using a flow coefficient representing the shape of the nozzle hole wall surface that affects the amount of deposit separation from the nozzle hole wall surface or a parameter correlated with the flow coefficient. Therefore, 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 addition, the parameter representing the factor that fluctuates the deposit peeling force in the present invention is not limited to a specific parameter, but is, for example, fuel injection pressure (that is, pressure of fuel injected from the fuel injection hole of the fuel injection valve). .

  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.

  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 substance generation amount, and at least a part of the deposit deposited on the nozzle hole wall surface is replaced with the nozzle hole wall surface. The amount of deposit peeling, which is the amount of deposit peeled from the wall surface of the nozzle hole, is estimated using a parameter representing a factor that fluctuates the deposit peeling force, which is the force for peeling from the nozzle hole. Then, a provisional deposit accumulation amount is calculated by subtracting the deposit peeling amount from the deposit constituent generation amount. Then, the provisional deposit amount is corrected in consideration of the flow coefficient relating to the fuel flowing through the fuel injection hole of the fuel injection valve or a parameter correlated with the flow coefficient as a factor affecting the deposit peeling force. As a result, the final deposit amount is calculated.

  According to the present invention, the deposit accumulation amount can be accurately estimated. That is, the parameter (for example, fuel injection pressure etc.) which shows the factor which fluctuates deposit peeling force as a factor which influences the deposit peeling amount is mentioned. That is, if this parameter varies, the deposit peeling amount also varies. However, even if this parameter is constant, the deposit peeling amount varies depending on the shape of the wall surface of the nozzle hole. That is, the shearing action applied to the deposit from the fuel flowing around the deposit differs depending on the shape of the wall surface of the nozzle hole. If the strength of this shearing action is large, the amount of deposit peeling from the wall surface of the nozzle hole increases. Furthermore, the occurrence of cavitation around the deposit varies depending on the shape of the wall surface of the nozzle hole. If the erosion strength in the cavitation is large, the amount of deposit peeling from the wall surface of the nozzle hole increases. Therefore, in order to estimate the deposit accumulation amount more accurately, the influence of the shape of the nozzle hole wall surface on the deposit peeling amount should be considered. Here, the research of the inventor of the present application revealed that the flow coefficient is a parameter representing the influence of the shape of the wall surface of the nozzle hole on the deposit peeling amount. That is, the smaller the flow coefficient, the greater the strength of the shearing action given to the deposit from the fuel flowing around the deposit, and the greater the amount of deposit peeling from the wall surface of the nozzle hole. Further, the smaller the flow coefficient, the greater the erosion strength in the cavitation around the deposit, and therefore the greater the amount of deposit peeling from the wall surface of the nozzle hole. Then, paying attention to the fact that there is a very close correlation between the influence of the shape of the nozzle hole wall surface on the deposit peeling amount from the nozzle hole wall surface and the influence of the flow coefficient on the deposit peeling amount, the present invention In this case, the deposit accumulation amount is calculated using a flow coefficient relating to the fuel flowing through the fuel injection hole or a parameter having a correlation with the flow coefficient. Thus, in the present invention, the deposit accumulation amount is calculated using a flow coefficient representative of the shape of the nozzle hole wall surface that affects the amount of deposit separation from the nozzle hole wall surface or a parameter correlated with the flow coefficient. Therefore, according to the present invention, the deposit accumulation 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 addition, the parameter representing the factor that fluctuates the deposit peeling force in the present invention is not limited to a specific parameter, but is, for example, fuel injection pressure (that is, pressure of fuel injected from the fuel injection hole of the fuel injection valve). .

  In yet another invention of the present application, in the above invention, the parameter having a correlation with the flow coefficient corresponds to a fuel spray angle, a fuel spray reach distance, a fuel injection rate in a nozzle hole throttling period, and a reference fuel injection command value. It is at least one of the correction amounts.

  The fuel spray angle of the present invention is specifically an angle at which the fuel spray formed by being injected from the fuel injection hole of the fuel injection valve spreads starting from the outlet of the fuel injection hole. The fuel spray reach distance of the present invention is specifically the distance from the outlet of the fuel injection hole where the fuel spray formed by being injected from the fuel injection hole of the fuel injection valve can reach. Further, the injection hole throttling period of the present invention is a period in which the throttle is applied mainly by the fuel injection holes to the flow of fuel injected from the fuel injection holes of the fuel injection valve. More specifically, the fuel injection rate is the amount of fuel injected from the fuel injection holes per unit time. Further, the reference fuel injection command value of the present invention is a command value predetermined as a command value to be given to the fuel injection valve in order to inject a required amount of fuel from the fuel injection valve. Specifically, the correction amount with respect to the reference fuel injection command value of the invention includes the required fuel injection amount (that is, the amount of fuel required as the amount of fuel injected from the fuel injection valve) and the actual fuel injection amount (that is, the required amount). When the reference fuel injection command value corresponding to the fuel injection amount is given to the fuel injection valve, the actual fuel injection amount is the required fuel when there is a difference between the actual fuel injection amount from the fuel injection valve) This is an amount for correcting the reference fuel injection command value corresponding to the required fuel injection amount so as to be the injection amount.

  According to the present invention, it is possible to more accurately estimate the deposit peeling amount. That is, obtaining the fuel spray angle, the fuel spray reach distance, or the fuel injection rate is easier than obtaining the flow coefficient relating to the fuel flowing through the fuel injection hole. Further, since the correction amount for the reference fuel injection command value is prepared as a correction for the reference fuel injection command value separately from the calculation of the deposit separation amount, obtaining the correction amount can be performed within the fuel injection hole. This is easier than finding the flow coefficient for the fuel flowing through. Since the fuel spray angle, the fuel spray reach distance, the fuel injection rate, and the correction amount for the reference fuel injection command value are parameters correlated with the flow coefficient, respectively, for the same reason as described above, By using at least one of the parameters to estimate the deposit peeling amount, the deposit peeling amount can be accurately estimated. Therefore, accurate estimation of the deposit peeling amount can be performed more easily.

  In yet another aspect of the present invention, in the above invention, the fuel injection rate is a maximum fuel injection rate in a nozzle hole throttle period.

  According to the present invention, it is possible to more accurately estimate the deposit peeling amount. That is, the fuel injection rate becomes the maximum fuel injection rate in the nozzle hole throttling period. Then, obtaining the maximum fuel injection rate is easier than obtaining fuel injection rates other than the maximum fuel injection rate in the nozzle hole throttling period. Since the maximum fuel injection rate is also a parameter having a correlation with the flow coefficient, the deposit separation amount is accurately estimated by using the maximum fuel injection rate for estimation of the deposit separation amount for the same reason as described above. The Therefore, accurate estimation of the deposit peeling amount can be performed more easily.

It is the figure which showed the internal combustion engine to which the deposit peeling amount estimation apparatus or deposit accumulation amount estimation apparatus of this 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 front-end | tip part of the fuel injection valve of the internal combustion engine shown by FIG. (A) is the figure which showed the relationship between the flow coefficient Cd and the fuel spray angle (theta) s, (B) is the figure which showed the relationship between the flow coefficient Cd and the fuel spray arrival distance Ls, (C) is a diagram showing the relationship between the flow coefficient Cd and the fuel injection rate dQ in the nozzle hole throttling period, and (D) is the relationship between the flow coefficient Cd and the correction amount QR for the reference fuel injection command value. FIG.

  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, and the temperature sensor 28. 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.

  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 one embodiment of the present invention (hereinafter referred to as “first embodiment”), the deposit peeling amount (hereinafter referred to as “deposit peeling amount”) in a predetermined period (that is, a predetermined period) according to the following equation 1 is used. Xr) is calculated. The predetermined period is not particularly limited and may be arbitrarily set. For example, the predetermined period is a period between two consecutive fuel injections in a specific fuel injection valve.

  Xr = b * Pin + c * (1 / Cd) (1)

  Note that “Pin” in Equation 1 is “a fuel injection pressure at a specific time point in the predetermined period (hereinafter simply referred to as“ fuel injection pressure ”)”. This fuel injection pressure is obtained from, for example, the output value of the pressure sensor 26 at a specific point in time during the predetermined period. Of course, instead of the fuel injection pressure at a specific point in time during the predetermined period, the average fuel injection pressure during the predetermined period may be used. Further, “Cd” in Expression 1 is “a flow coefficient relating to fuel flowing through the fuel injection hole (hereinafter simply referred to as“ flow coefficient ”)”. This flow coefficient is, for example, a coefficient obtained in advance by experiments or the like. Of course, if there is a means for appropriately measuring the flow coefficient during engine operation, the flow coefficient thus measured may be used. Further, “b” in Equation 1 is a coefficient adapted so that the deposit separation amount related to the fuel injection pressure Pin can be accurately calculated. In addition, “c” in Equation 1 is a coefficient adapted to accurately calculate the deposit peeling amount related to the flow coefficient. As shown in Equation 1, the new deposit separation amount Xr is determined by the deposit separation amount b × Pin that can be grasped in relation to the fuel injection pressure Pin and the deposit separation amount c × that can be grasped in relation to the flow coefficient Cd. It is the sum of (1 / Cd). In other words, the new deposit separation amount Xr is calculated as a function of the fuel injection pressure Pin and the flow coefficient Cd. And the deposit new peeling amount Xr calculated according to Equation 1 is larger as the fuel injection pressure Pin is higher and larger as the flow coefficient Cd is smaller.

  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. “Xr” in Equation 3 is the deposit new peel amount calculated according to Equation 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 new peel amount can be accurately estimated. That is, the fuel injection pressure can be cited as a factor affecting the deposit new peel amount. That is, the higher the fuel injection pressure, the larger the deposit new peel amount. However, even if the fuel injection pressure is constant, the deposit new peel amount varies depending on the shape of the wall surface of the nozzle hole. That is, the shearing action applied to the deposit from the fuel flowing around the deposit differs depending on the shape of the wall surface of the nozzle hole. If the strength of this shearing action is large, the amount of deposit peeling from the wall surface of the nozzle hole increases. Furthermore, the occurrence of cavitation around the deposit varies depending on the shape of the wall surface of the nozzle hole. If the erosion strength in the cavitation is large, the amount of deposit peeling from the wall surface of the nozzle hole increases. Therefore, in order to estimate the deposit new peeling amount more accurately, the influence of the shape of the nozzle hole wall surface on the deposit peeling amount should be considered. Here, the research of the inventor of the present application revealed that the flow coefficient is a parameter that represents the influence of the shape of the wall surface of the nozzle hole on the deposit peeling amount. That is, the smaller the flow coefficient, the greater the strength of the shearing action given to the deposit from the fuel flowing around the deposit, and the greater the amount of deposit peeling from the wall surface of the nozzle hole. Further, the smaller the flow coefficient, the greater the erosion strength in the cavitation around the deposit, and therefore the greater the amount of deposit peeling from the wall surface of the nozzle hole. Then, paying attention to the fact that there is a very close correlation between the influence of the shape of the nozzle hole wall surface on the deposit peeling amount from the nozzle hole wall surface and the influence of the flow coefficient on the deposit peeling amount, In the embodiment, the new deposit separation amount is calculated according to Equation 1 including the flow coefficient as a parameter. As described above, in the first embodiment, the new deposit separation amount is calculated using the flow coefficient representative of the shape of the nozzle hole wall surface that affects the amount of deposit separation from the nozzle hole wall surface. According to the embodiment, the deposit new peeling amount can be accurately estimated.

  Further, according to the first embodiment, it can be said that the influence of the shape of the nozzle hole wall surface on the deposit peeling amount from the nozzle hole wall surface can be reflected relatively easily in the calculation of the new deposit peeling amount. In other words, if the effect of the shape of the nozzle hole wall on the deposit separation is to be reflected in the calculation of the new deposit separation using the shape of the nozzle wall itself, the shape of the nozzle hole wall must be grasped as a numerical value. I must. However, it is difficult to grasp the shape of the wall surface of the nozzle hole as a numerical value. On the other hand, it is easier to obtain the flow coefficient relating to the flow of fuel flowing through the fuel injection hole than to quantify the shape of the wall surface of the injection hole. Here, in the first embodiment, this flow coefficient is reflected in the calculation of the new deposit separation amount, and this flow coefficient is closely correlated with the influence of the shape of the nozzle hole wall surface on the deposit peeling amount from the nozzle hole wall surface. Since there is a relationship, according to the first embodiment, it can be said that the influence of the shape of the nozzle hole wall surface on the deposit peeling amount from the nozzle hole wall surface can be reflected relatively easily in the calculation of the new deposit peeling amount. It is.

  In addition, according to the first embodiment, since the deposit peeling amount necessary for calculating the total deposit accumulation amount can be accurately estimated, the total deposit accumulation amount can be accurately estimated.

  In the first embodiment, the total deposit accumulation amount, which is the amount of deposit deposited on the nozzle hole wall surface, is estimated. However, the concept of the present invention included in the first embodiment is to deposit on the nozzle hole wall surface. The present invention is also applicable when estimating the thickness of a deposit.

  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 Although the total deposit accumulation amount is estimated, the concept of the present invention included in the first embodiment peels from any one of the wall surface near the nozzle hole outlet, the wall near the nozzle hole defining wall, and the wall near the nozzle hole inlet. The present invention is also applicable to the case where the new deposit amount is estimated and the new deposit amount and the total deposit amount deposited on the one wall surface are estimated.

  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.

  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 first 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 first 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.

  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 time the predetermined period elapses.

  When the routine of FIG. 3 is started, in step 100, the fuel injection pressure Pin, the nozzle hole temperature Tn, the metal component concentration Cm, and the flow coefficient Cd 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. By applying the injection pressure Pin and the flow coefficient Cd to the above equation 1, the new deposit separation amount Xr is calculated.

  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, a deposit peeling amount (that is, 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 arbitrarily set. For example, the predetermined period is a period between two consecutive fuel injections in a specific fuel injection valve.

  Xr = b × Pin (5)

  “Pin” in Equation 5 is “a fuel injection pressure at a specific time point in the predetermined period (hereinafter simply referred to as“ fuel injection pressure ”)”. This fuel injection pressure is obtained from, for example, the output value of the pressure sensor 26 at a specific point in time during the predetermined period. Of course, instead of the fuel injection pressure at a specific point in time during the predetermined period, the average fuel injection pressure during the predetermined period may be used. 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 Expression 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 2 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 = F (PXd, Cd) (8)

  Note that “PXd” in Expression 8 is the provisional deposit new deposition amount calculated according to Expression 7. Further, “Cd” in Expression 8 is “a flow coefficient relating to the fuel flowing through the fuel injection hole (hereinafter simply referred to as“ flow coefficient ”). This flow coefficient is, for example, a coefficient obtained in advance by experiments or the like. Of course, if there is a means for appropriately measuring the flow coefficient during engine operation, the flow coefficient thus measured may be used. Further, “F (PXd, Cd)” in Expression 8 is a function of the temporary deposit new deposition amount PXd and the flow coefficient Cd, and the deposit new deposition amount is accurately determined based on the provisional deposit new deposition amount and the flow coefficient. It is a function adapted so that it can be calculated. The new deposit amount Xd calculated according to the equation 8 is larger as the provisional deposit new deposit amount is larger, and is smaller as the flow coefficient is smaller (that is, the smaller the flow coefficient is, the larger the deposit peeling amount is).

  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. Then, as shown in Equation 9, the total deposit accumulation amount TXd is calculated by integrating the new deposit accumulation amount Xd.

  According to the second embodiment, the total deposit accumulation amount can be accurately estimated. That is, the fuel injection pressure can be cited as a factor affecting the deposit new peel amount. That is, the higher the fuel injection pressure, the larger the deposit new peel amount. However, even if the fuel injection pressure is constant, the deposit new peel amount varies depending on the shape of the wall surface of the nozzle hole. That is, the shearing action applied to the deposit from the fuel flowing around the deposit differs depending on the shape of the wall surface of the nozzle hole. If the strength of this shearing action is large, the amount of deposit peeling from the wall surface of the nozzle hole increases. Furthermore, the occurrence of cavitation around the deposit varies depending on the shape of the wall surface of the nozzle hole. If the erosion strength in the cavitation is large, the amount of deposit peeling from the wall surface of the nozzle hole increases. Therefore, in order to estimate the total deposit accumulation amount more accurately, the influence of the shape of the nozzle hole wall surface on the deposit peeling amount should be considered. Here, the research of the inventor of the present application revealed that the flow coefficient is a parameter that represents the influence of the shape of the wall surface of the nozzle hole on the deposit peeling amount. That is, the smaller the flow coefficient, the greater the strength of the shearing action given to the deposit from the fuel flowing around the deposit, and the greater the amount of deposit peeling from the wall surface of the nozzle hole. Further, the smaller the flow coefficient, the greater the erosion strength in the cavitation around the deposit, and therefore the greater the amount of deposit peeling from the wall surface of the nozzle hole. Then, paying attention to the fact that there is a very close correlation between the influence of the shape of the nozzle hole wall surface on the deposit peeling amount from the nozzle hole wall surface and the influence of the flow coefficient on the deposit peeling amount, In the embodiment, the final new deposit amount is calculated by correcting the temporary new deposit amount calculated as the temporary new deposit amount according to Equation 7 with the flow coefficient according to Equation 8. Thus, in the second embodiment, since the final deposit new deposition amount is calculated using the flow coefficient representative of the shape of the nozzle hole wall surface that affects the amount of deposit separation from the nozzle hole wall surface, According to the second embodiment, the total deposit accumulation amount can be accurately estimated.

  Further, according to the second embodiment, it can be said that the influence of the shape of the nozzle hole wall surface on the deposit peeling amount from the nozzle hole wall surface can be reflected relatively easily in the calculation of the total deposit accumulation amount. In other words, if the effect of the shape of the nozzle hole wall on the deposit separation is to be reflected in the calculation of the total deposit accumulation amount using the nozzle hole wall shape itself, the shape of the nozzle hole wall must be grasped as a numerical value. I must. However, it is difficult to grasp the shape of the wall surface of the nozzle hole as a numerical value. On the other hand, it is easier to obtain the flow coefficient relating to the flow of fuel flowing through the fuel injection hole than to quantify the shape of the wall surface of the injection hole. Here, in the second embodiment, this flow coefficient is reflected in the calculation of the total deposit accumulation amount, and this flow coefficient has a close correlation with the effect of the shape of the nozzle hole wall surface on the deposit peeling amount from the hole hole wall surface. Therefore, according to the second embodiment, it can be said that the influence of the shape of the nozzle hole wall surface on the deposit peeling amount from the nozzle hole wall surface can be reflected relatively easily in the calculation of the total deposit accumulation amount. It is.

  In the second embodiment, the total deposit accumulation amount, which is the amount of deposit deposited on the nozzle hole wall surface, is estimated. However, the concept of the present invention included in the second embodiment is to deposit on the nozzle hole wall surface. The present invention is also applicable when estimating the thickness of a deposit.

  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, but the concept of the present invention included in the second embodiment is that the nozzle hole vicinity wall surface, the nozzle hole defining wall surface, and the nozzle hole inlet port Estimate the new deposit amount peeled from any one of the nearby wall surfaces, and estimate the new temporary deposit amount, the final new deposit amount, and the total deposit amount deposited on the one wall surface. It is also applicable to

  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.

  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 second 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 decomposes is known in advance, in the second embodiment, the temperature around the deposit is acquired 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.

  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 time the predetermined period elapses.

  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 flow coefficient Cd 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 flow coefficient Cd acquired in step 200 to the above equation 8. 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 above-described embodiment, the flow coefficient is used for calculating the total deposit accumulation amount in order to reflect the influence of the shape of the nozzle hole wall surface on the deposit separation amount from the nozzle hole wall surface in the calculation of the total deposit accumulation amount. . However, a parameter having a close correlation with the flow coefficient may be used instead of the flow coefficient. This parameter only needs to have a close correlation with the flow coefficient, and is not limited to a specific parameter. For example, the fuel spray angle, the fuel spray reach distance, the fuel injection rate in the nozzle hole throttling period, the reference fuel injection This is the correction amount for the command value.

  Here, in detail, the fuel spray angle is an angle at which the fuel spray formed by being injected from the fuel injection hole of the fuel injection valve spreads from the outlet of the fuel injection hole as a starting point (indicated by reference sign θs in FIG. 5). Angle).

  Further, the fuel spray reach distance is, in detail, a distance (a distance indicated by a reference symbol Ls in FIG. 5) at which the fuel spray formed by being injected from the fuel injection hole of the fuel injection valve can reach. is there.

  Further, the fuel injection rate in the nozzle hole throttling period is specifically the amount of fuel injected from the fuel injection hole of the fuel injection valve per unit time in the nozzle hole throttling period. Is a period during which the throttle is mainly applied by the fuel injection hole to the flow of fuel injected from the fuel injection hole of the fuel injection valve. That is, the needle of the fuel injection valve blocks the fuel injection from the fuel injection hole (that is, the needle so that the outer peripheral wall surface of the tapered tip of the needle is in contact with the inner peripheral wall of the nozzle tip. Is positioned in the nozzle, and this state is hereinafter referred to as “fully closed state”), the fuel injection rate is zero. The needle is positioned in the nozzle so that the outer peripheral wall surface of the tapered tip of the needle is located farthest from the inner peripheral wall surface of the tip of the nozzle. In the initial stage, the space between the outer peripheral wall surface of the tapered tip of the needle and the inner peripheral wall surface of the tip of the nozzle is restricted against the flow of fuel injected from the fuel injection hole. become. However, if the needle continues to move toward the fully open state, the space between the outer peripheral wall surface of the tapered tip end portion of the needle and the inner peripheral wall surface of the tip end portion of the nozzle becomes sufficiently large. The throttle for the flow of fuel to be injected gradually shifts from this space to the fuel injection hole. Eventually, the restriction on the flow of fuel injected from the fuel injection hole mainly becomes the fuel injection hole. The period in which the throttle with respect to the flow of fuel injected from the fuel injection hole is mainly the fuel injection hole is the nozzle hole throttle period. The amount of fuel injected from the fuel injection hole per unit time in the injection hole throttle period is the fuel injection rate in the injection hole throttle period.

  Note that the fuel injection rate during the nozzle hole throttling period may be a fuel injection rate at a specific point in time during the nozzle hole throttling period, or may be an average fuel injection rate during the nozzle hole throttling period. Further, when the fuel injection rate is obtained during the nozzle hole throttling period, the fuel injection rate that is relatively easily obtained is the maximum fuel injection rate. Therefore, the maximum fuel injection rate in the nozzle hole throttle period may be used as the fuel injection rate in the nozzle hole throttle period.

  Further, the correction amount with respect to the reference fuel injection command value is specifically a correction amount set as follows. The command value to be given to the fuel injection valve to inject the fuel of the required fuel injection amount (that is, the amount of fuel required as the amount of fuel injected from the fuel injection valve) from the reference fuel injection valve is the reference fuel injection It is obtained in advance as a command value. The difference between the actual fuel injection amount (that is, the amount of fuel actually injected from each fuel injection valve) when the reference fuel injection command value is given to each individual fuel injection valve and the required fuel injection amount When there is, the amount for correcting the reference fuel injection command value corresponding to the required fuel injection amount is set so that the actual fuel injection amount becomes the required fuel injection amount. This amount is a correction amount for the reference fuel injection command value.

  In the first embodiment, when the fuel spray angle is used instead of the flow coefficient, the following expression 10 is used instead of expression 1.

  Xr = b × Pin + c × θs (10)

  “Pin” in Expression 10 is the same “fuel injection pressure” as “Pin” in Expression 1. Further, “θs” in Expression 10 is the fuel spray angle. The fuel spray angle is, for example, a fuel spray angle obtained in advance by experiments or the like. If there is a means for appropriately measuring the fuel spray angle during engine operation, the fuel spray angle measured by the means is measured. An angle may be used. Further, “b” in Expression 10 is a coefficient adapted to accurately calculate the deposit separation amount related to the fuel injection pressure Pin. Further, “c” in Expression 10 is a coefficient adapted so that the deposit separation amount related to the fuel spray angle θs can be accurately calculated.

  As can be seen from Equation 10, when the fuel spray angle θs is reflected in the calculation of the new deposit separation amount Xr, the new deposit separation amount Xr is the deposit separation amount b × Pin that can be grasped in relation to the fuel injection pressure Pin. This is the total of the deposit peeling amount c × θs that can be grasped in relation to the fuel spray angle θs. In other words, the new deposit separation amount Xr is calculated as a function of the fuel injection pressure Pin and the fuel spray angle θs.

  Further, as can be seen from Equation 10, the higher the fuel injection pressure Pin, the greater the new deposit separation amount Xr, and the greater the fuel spray angle θs, the greater the new deposit separation amount Xr. That is, as shown in FIG. 6A, there is a correlation between the fuel spray angle θs and the flow coefficient Cd that the fuel spray angle increases as the flow coefficient decreases. Since the fuel spray angle having a close correlation with the flow coefficient is used for calculating the new deposit amount by calculating the new deposit amount in accordance with Equation 10, the description will be made in connection with the first embodiment. For the same reason as described above, the deposit new peel amount can be accurately estimated.

  Also, obtaining the fuel spray angle is easier than obtaining the flow coefficient. Therefore, according to Equation 10, for the same reason as described in relation to the first embodiment, the influence of the shape of the nozzle hole wall surface on the deposit peeling can be more easily reflected in the calculation of the deposit peeling amount. .

  On the other hand, when the fuel spray angle is used instead of the flow coefficient in the second embodiment, the following equation 11 is used instead of equation 8.

  Xd = F (PXd, θs) (11)

  Note that “PXd” in Expression 11 is a temporary deposit new deposition amount calculated according to Expression 7. Further, “θs” in Expression 11 is the “fuel spray angle”. The fuel spray angle is, for example, a fuel spray angle obtained in advance by experiments or the like. If there is a means for appropriately measuring the fuel spray angle during engine operation, the fuel spray angle measured by the means is measured. An angle may be used. Further, “F (PXd, θs)” in Expression 11 is a function of the provisional deposit new deposition amount PXd and the fuel spray angle θs, and the deposit new deposition amount based on the provisional deposit new deposition amount and the fuel spray angle. Is a function adapted so that can be calculated accurately. Note that the new deposit deposit amount calculated according to Equation 11 is larger as the provisional deposit new deposit amount PXd is larger, and is smaller as the fuel spray angle is larger (that is, the larger the fuel spray angle is, the larger the deposit peeling amount is).

  Then, by calculating the new deposit amount in accordance with Equation 11, the fuel spray angle having a close correlation with the flow coefficient is used for calculating the new deposit amount. Therefore, the description will be made in relation to the second embodiment. For the same reason as described above, the new deposit amount can be accurately estimated.

  Also, obtaining the fuel spray angle is easier than obtaining the flow coefficient. Therefore, according to Equation 11, for the same reason as described in relation to the second embodiment, it is possible to more easily reflect the influence of the shape of the nozzle hole wall surface on the deposit separation in the calculation of the new deposit amount. it can.

  Further, when the fuel spray reach distance is used instead of the flow coefficient in the first embodiment, the following expression 12 is used instead of the expression 1.

  Xr = b * Pin + c * (1 / Ls) (12)

  “Pin” in Expression 12 is the same “fuel injection pressure” as “Pin” in Expression 1. Further, “Ls” in Expression 12 is the fuel spray reach distance. The fuel spray reach distance is, for example, a fuel spray reach distance obtained in advance by experiments or the like. If there is a means for appropriately measuring the fuel spray reach distance during engine operation, the fuel spray reach distance is measured by that means. The fuel spray reach distance may be used. In addition, “b” in Expression 12 is a coefficient adapted to accurately calculate the deposit separation amount related to the fuel injection pressure Pin, and “c” in Expression 12 is related to the fuel spray reach distance Ls. It is a coefficient adapted to accurately calculate the deposit peeling amount.

  As can be seen from Equation 12, when the fuel spray arrival distance Ls is reflected in the calculation of the new deposit separation amount Xr, the new deposit separation amount Xr is the deposit separation amount b × Pin that can be grasped in relation to the fuel injection pressure Pin. And the deposit separation amount c × (1 / Ls) that can be grasped in relation to the fuel spray arrival distance Ls. In other words, the new deposit separation amount Xr is calculated as a function of the fuel injection pressure Pin and the fuel spray reach distance Ls.

  Further, as can be seen from Equation 12, the higher the fuel injection pressure Pin, the larger the new deposit separation amount Xr, and the shorter the fuel spray arrival distance Ls, the greater the new deposit separation amount Xr. That is, as shown in FIG. 6B, there is a correlation between the fuel spray arrival distance Ls and the flow coefficient Cd that the fuel spray arrival distance becomes shorter as the flow coefficient decreases. Since the fuel spray arrival distance having a close correlation with the flow coefficient is used for calculation of the new deposit separation amount by calculating the new deposit separation amount according to Equation 12, this is related to the first embodiment. For the same reason as described, the deposit new peel amount can be accurately estimated.

  Further, obtaining the fuel spray reach distance is easier than obtaining the flow coefficient. Therefore, according to Expression 12, for the same reason as described in relation to the first embodiment, the influence of the shape of the nozzle hole wall surface on the deposit peeling can be more easily reflected in the calculation of the deposit peeling amount. .

  On the other hand, when the fuel spray reach distance is used instead of the flow coefficient in the second embodiment, the following equation 13 is used instead of equation 8.

  Xd = F (PXd, Ls) (13)

  Note that “PXd” in Expression 13 is a provisional deposit new deposition amount calculated according to Expression 7. Further, “Ls” in Expression 13 is the “fuel spray reach distance”. The fuel spray reach distance is, for example, a fuel spray reach distance obtained in advance by experiments or the like. If there is a means for appropriately measuring the fuel spray reach distance during engine operation, the fuel spray reach distance is measured by that means. The fuel spray reach distance may be used. Further, “F (PXd, Ls)” in Expression 13 is a function of the provisional deposit new accumulation amount PXd and the fuel spray arrival distance Ls, and the deposit new based on the provisional deposit new accumulation amount and the fuel spray arrival distance. It is a function adapted so that the amount of deposition can be calculated accurately. It should be noted that the new deposit deposit amount calculated according to Equation 13 increases as the provisional deposit new deposit amount PXd increases, and decreases as the fuel spray arrival distance decreases (that is, the deposit separation amount increases as the fuel spray arrival distance decreases). .

  Then, by calculating the new deposit amount according to Equation 13, the fuel spray arrival distance having a close correlation with the flow coefficient is used for calculating the new deposit amount. Therefore, in relation to the second embodiment, For the same reason as explained, the new deposit amount can be accurately estimated.

  Further, obtaining the fuel spray reach distance is easier than obtaining the flow coefficient. Therefore, according to Equation 13, for the same reason as described in relation to the second embodiment, it is possible to more easily reflect the influence of the shape of the nozzle hole wall surface on the peeling of the deposit in the calculation of the new deposit amount. it can.

  Further, in the first embodiment, when the fuel injection rate in the injection hole throttle period is used instead of the flow coefficient, the following equation 14 is used instead of equation 1.

  Xr = b * Pin + c * (1 / dQ) (14)

  “Pin” in Expression 14 is the same “fuel injection pressure” as “Pin” in Expression 1. Further, “dQ” in Expression 14 is the fuel injection rate in the nozzle hole throttling period. The fuel injection rate may be, for example, a fuel injection rate obtained in advance by experiments or the like. If the internal combustion engine is provided with means for measuring the fuel injection rate, the means during engine operation is used. The fuel injection rate measured by “B” in Expression 14 is a coefficient adapted to accurately calculate the deposit separation amount related to the fuel injection pressure Pin, and “c” in Expression 14 is a deposit related to the fuel injection rate dQ. The coefficient is adapted so that the amount of peeling can be accurately calculated.

  As can be seen from Equation 14, when the fuel injection rate dQ is reflected in the calculation of the new deposit separation amount Xr, the new deposit separation amount Xr is the deposit separation amount b × Pin that can be grasped in relation to the fuel injection pressure Pin. It is the sum of the deposit peeling amount c × (1 / dQ) that can be grasped in relation to the fuel injection rate dQ. In other words, the new deposit separation amount Xr is calculated as a function of the fuel injection pressure Pin and the fuel injection rate dQ.

  Further, as can be seen from Equation 14, the higher the fuel injection pressure Pin, the larger the new deposit separation amount Xr, and the smaller the fuel injection rate dQ, the greater the new deposit separation amount Xr. That is, as shown in FIG. 6C, there is a correlation between the fuel injection rate dQ and the flow rate coefficient Cd that the fuel injection rate decreases as the flow rate coefficient decreases. Since the fuel injection rate having a close correlation with the flow coefficient is used for calculating the new deposit amount by calculating the new deposit amount according to the equation 14, the description will be made in relation to the first embodiment. For the same reason as described above, the deposit new peel amount can be accurately estimated.

  Further, obtaining the fuel injection rate is easier than obtaining the flow coefficient. Therefore, according to Equation 14, for the same reason as described in relation to the first embodiment, the influence of the shape of the nozzle hole wall surface on the deposit peeling can be more easily reflected in the calculation of the deposit peeling amount. .

  On the other hand, in the second embodiment, when the fuel injection rate in the nozzle hole throttling period is used instead of the flow coefficient, the following equation 15 is used instead of equation 8.

  Xd = F (PXd, dQ) (15)

  Note that “PXd” in Equation 15 is a provisional deposit new deposition amount calculated according to Equation 7. Further, “dQ” in Expression 15 is “the fuel injection rate in the nozzle hole throttling period”. The fuel injection rate may be, for example, a fuel injection rate that is obtained in advance through experiments or the like, and when the internal combustion engine is provided with means for measuring the fuel injection rate, the fuel injection rate is measured by the means during engine operation. It may be a fuel injection rate. Further, “F (PXd, dQ)” in Expression 15 is a function of the provisional deposit new deposition amount PXd and the fuel injection rate dQ, and the deposit new deposition amount based on the provisional deposit new deposition amount and the fuel injection rate. Is a function adapted so that can be calculated accurately. It should be noted that the new deposit deposit amount calculated according to Equation 15 increases as the provisional deposit new deposit amount PXd increases, and decreases as the fuel injection rate increases (that is, as the fuel injection rate increases, the deposit separation amount increases).

  Since the fuel injection rate having a close correlation with the flow coefficient is used for calculating the new deposit amount by calculating the new deposit amount according to Expression 15, the description will be made in relation to the second embodiment. For the same reason as described above, the new deposit amount can be accurately estimated.

  Further, obtaining the fuel injection rate is easier than obtaining the flow coefficient. Therefore, according to Equation 15, for the same reason as described in relation to the second embodiment, it is possible to more easily reflect the influence of the shape of the nozzle hole wall surface on the peeling of the deposit in the calculation of the new deposit amount. it can.

  Further, in the first embodiment, when a correction amount for the reference fuel injection command value is used instead of the flow coefficient, the following equation 16 is used instead of equation 1.

  Xr = b × Pin + c × QR (16)

  Note that “Pin” in Expression 16 is the same “fuel injection pressure” as “Pin” in Expression 1. Further, “QR” in Expression 16 is a correction amount for the reference fuel injection command value. This correction amount is a correction amount set in the control of the fuel injection amount, and is obtained from the control of the fuel injection amount. In addition, “b” in Expression 16 is a coefficient adapted to accurately calculate the deposit separation amount related to the fuel injection pressure Pin, and “c” in Expression 16 is a correction amount for the reference fuel injection command value. A coefficient adapted to accurately calculate the amount of deposit peeling related to QR.

  As can be seen from Equation 16, when the correction amount QR with respect to the reference fuel injection command value is reflected in the calculation of the new deposit separation amount Xr, the new deposit separation amount Xr can be grasped in relation to the fuel injection pressure Pin. This is the sum of the amount b × Pin and the deposit separation amount c × QR that can be grasped in relation to the correction amount QR with respect to the reference fuel injection command value. In other words, the new deposit separation amount Xr is calculated as a function of the fuel injection pressure Pin and the correction amount QR with respect to the reference fuel injection command value.

  Further, as can be seen from Equation 16, the higher the fuel injection pressure Pin, the greater the new deposit separation amount Xr, and the greater the correction amount QR for the reference fuel injection command value, the greater the new deposit separation amount Xr. That is, as shown in FIG. 6D, the correction amount for the reference fuel injection command value increases as the flow coefficient decreases between the correction amount QR for the reference fuel injection command value and the flow coefficient Cd. There will be a correlation. Then, by calculating the deposit new peel amount according to Equation 16, the correction amount for the reference fuel injection command value having a close correlation with the flow coefficient is used for calculating the deposit new peel amount. For the same reason as described in connection with the above, it is possible to accurately estimate the new deposit peeling amount.

  Further, since the correction amount for the reference fuel injection command value is a correction amount set in the control of the fuel injection amount, obtaining this correction amount is easier than obtaining the flow coefficient. Therefore, according to Equation 16, for the same reason as described in connection with the first embodiment, the influence of the shape of the nozzle hole wall surface on the deposit peeling can be more easily reflected in the calculation of the deposit peeling amount. .

  On the other hand, when the correction amount for the reference fuel injection command value is used instead of the flow coefficient in the second embodiment, the following equation 17 is used instead of equation 8.

  Xd = F (PXd, QR) (17)

  Note that “PXd” in Expression 17 is a provisional deposit new deposition amount calculated according to Expression 7. Further, “QR” in Expression 17 is “a correction amount with respect to the reference fuel injection command value”. This correction amount is a correction amount set in the control of the fuel injection amount, and is obtained from the control of the fuel injection amount. Further, “F (PXd, QR)” in Expression 17 is a function of the provisional deposit new accumulation amount PXd and the correction amount QR with respect to the reference fuel injection command value, and the provisional deposit new accumulation amount and the reference fuel injection command value are related to each other. It is a function adapted so that a new deposit amount can be accurately calculated based on the correction amount. Note that the new deposit amount calculated in accordance with Equation 17 increases as the provisional deposit new deposit amount PXd increases, and decreases as the correction amount for the reference fuel injection command value increases (that is, the correction amount for the reference fuel injection command value increases). The more the amount of deposit peeled off).

  Then, by calculating the deposit new deposit amount according to the equation 17, the correction amount for the reference fuel injection command value having a close correlation with the flow coefficient is used for calculating the deposit new deposit amount. For the same reason as described above, it is possible to accurately estimate the new deposit amount.

  Further, since the correction amount for the reference fuel injection command value is a correction amount set in connection with the control of the fuel injection amount, obtaining this correction amount is easier than obtaining the flow coefficient. Therefore, according to the equation 17, for the same reason as described in relation to the second embodiment, it is possible to more easily reflect the influence of the shape of the nozzle hole wall surface on the deposit separation in the calculation of the new deposit amount. it can.

  Instead of the flow coefficient, any one of a fuel spray angle, a fuel spray reach distance, a fuel injection rate during the nozzle hole throttling period, and a correction amount for the reference fuel injection command value is calculated as a new deposit amount or a total deposit Although the embodiment used for calculating the accumulation amount has been described, two or more of the fuel spray angle, the fuel spray reach distance, the fuel injection rate in the nozzle hole throttling period, and the correction amount for the reference fuel injection command value May be used for calculating the new deposit amount or calculating the total deposit amount.

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

  Further, if the pressure in the atmosphere around the outlet of the fuel injection hole of the fuel injection valve is different, the deposit peeling amount affected by the fuel injection pressure is different even if the fuel injection pressure is equal. Specifically, the lower the pressure in the atmosphere around the outlet of the fuel injection hole, the greater the amount of deposit peeling that is affected by the fuel injection pressure. Therefore, in the above-described embodiment, the deposit separation amount related to the fuel injection pressure may be calculated using the pressure of the atmosphere around the outlet of the fuel injection hole in addition to the fuel injection pressure.

  Further, if the deposits deposited on the wall surface of the nozzle hole are different in thickness, the deposit peeling amount affected by the fuel injection pressure is different even if the fuel injection pressure is equal. Specifically, the deposit peeling amount affected by the fuel injection pressure increases as the thickness of the deposit accumulated on the wall surface of the nozzle hole increases. Therefore, in the above-described embodiment, in addition to the fuel injection pressure, the thickness of deposit deposited on the wall surface of the nozzle hole (or the total deposit accumulation amount that can represent the thickness) is used to relate to the fuel injection pressure. The deposit peeling amount may be calculated.

  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, 21 ... Combustion chamber, 22 ... Fuel injection valve, 34 ... Fuel injection hole, Cd ... Flow coefficient, [theta] s ... Fuel spray angle, Ls ... Fuel spray arrival distance, dQ ... Fuel injection rate in nozzle hole throttling period , QR: Correction amount for the reference fuel injection command value

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 peeling amount estimation device for estimating a peeling amount, wherein at least one of the plurality of parameters is a parameter representing a factor that varies the deposit peeling force, The number of different at least one deposit peeling quantity estimation apparatus is a parameter correlated relationship between flow coefficient or the flow rate coefficient for the fuel flowing through the fuel injection hole of the fuel injection valve parameters.   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 device for estimating a deposit accumulation amount by calculating a deposit accumulation amount, comprising the deposit peeling amount estimation device according to claim 1, and a generation amount of a deposit constituent material constituting the deposit Is estimated as the deposit constituent generation amount, and the deposit peeling amount is estimated by the deposit peeling amount estimation device, and the deposit constituent substance generation amount is used to estimate the deposit from the deposit constituent substance generation amount. Deposit amount estimation device which deposit amount is calculated by subtracting the Hanareryou.   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 device for estimating a deposit accumulation amount by calculating a deposit accumulation amount, wherein the generation amount of a deposit constituent material constituting the deposit is estimated as a deposit constituent material generation amount and the wall surface of the nozzle hole It is possible to determine whether or not the nozzle hole wall surface uses a parameter representing a factor that varies the deposit peeling force, which is a force for peeling at least part of the deposit deposited on the nozzle hole wall surface. The amount of deposit peeling, which is the amount of deposit to be peeled off, is estimated, the provisional deposit accumulation amount is calculated by subtracting the deposit peeling amount from the deposit constituent generation amount, and the fuel flowing in the fuel injection hole of the fuel injection valve The final deposit accumulation amount is calculated by correcting the provisional deposit accumulation amount in consideration of the flow coefficient relating to the flow coefficient or a parameter correlated with the flow coefficient as a factor affecting the deposit peeling force. Accumulation device.   2. The parameter correlated to the flow coefficient is at least one of a fuel spray angle, a fuel spray reach distance, a fuel injection rate in a nozzle hole throttling period, and a correction amount for a reference fuel injection command value. The deposit peeling amount estimation apparatus of Claim or the deposit accumulation amount estimation apparatus of Claim 2 or 3.   The deposit peeling amount estimation apparatus or deposit accumulation amount estimation apparatus according to claim 4, wherein the fuel injection rate is a maximum fuel injection rate in a nozzle hole throttling period.

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