JP5999364B2 - Control device for fuel injection system - Google Patents

Description

  The present invention is applied to a fuel injection system that includes an injection nozzle that injects fuel, and fuel pressure adjusting means that can adjust the pressure of fuel injected into the injection nozzle (hereinafter also referred to as “fuel pressure”). The present invention relates to a control device.

  As an example of a fuel injection system applied to an internal combustion engine (particularly, an in-cylinder internal combustion engine), a so-called common rail fuel injection system can be cited. In order to inject a desired amount of fuel into a combustion chamber (in-cylinder) at a desired timing, this fuel injection system is an injection nozzle that can inject fuel according to an instruction about the amount of fuel and the timing of injection (for example, , A high-pressure injector) and fuel pressure adjusting means (for example, a common rail and a supply pump) that can adjust the pressure of fuel injected into the injection nozzle.

  The injection nozzle generally includes an injection hole through which fuel is ejected, a flow path for guiding the fuel to the injection hole, and a valve body (for example, a needle) capable of adjusting the opening area of the flow path. The opening area of the flow path is adjusted by moving the valve body using a solenoid or piezo or the like (see, for example, FIG. 2).

  One of the conventional fuel injection systems (hereinafter also referred to as “conventional system”) is, for example, by devising the shape of the nozzle hole of the injection nozzle, for example, characteristics of fuel injected from the nozzle hole (for example, The degree of atomization) is improved (for example, refer to Patent Document 1).

JP 2012-14504 A

  The general operation principle of the injection nozzle will be described. The injection nozzle has a force to reduce the opening area of the flow path due to the pressure (fuel pressure) of the fuel injected into the injection nozzle, a solenoid or the like. A force to increase the opening area of the flow path due to the operation is exerted on the valve body (needle). Further, the valve body moves in a direction to reduce the opening area when the solenoid or the like is not operated, and closes the flow path, and moves and flows in a direction to increase the opening area when the solenoid or the like is in operation. Designed to open the road. Then, a solenoid or the like is actuated in response to an instruction for injecting fuel (instruction on the amount of fuel and the timing of injection), whereby the flow path is opened and closed, and the injection nozzle is operated at an amount and timing according to the instruction. Fuel will be injected.

  By the way, in the injection nozzle that operates as described above, generally, the valve element is present at a predetermined seating position when the flow path is closed (when the opening area is zero), and when the flow path is opened (opening). When the area is enlarged), the seat is moved away (lifted). Therefore, hereinafter, the degree of opening of the flow path by the valve body is also referred to as the “lift amount” of the valve body. That is, “large lift” means that the opening area of the flow path is large, and “small lift” means that the opening area of the flow path is small.

  When the fuel is injected from the injection nozzle, the valve element is usually operated so that the lift amount becomes maximum (the opening area of the flow path becomes maximum). Thereby, the pressure loss resulting from the valve body is reduced, and the fuel pressure on the downstream side of the valve body (corresponding to the fuel pressure in the injection hole) is brought close to the fuel pressure on the upstream side of the valve body (corresponding to the fuel pressure at the injection nozzle injection). (Or substantially match). In general, the higher the fuel pressure in the nozzle hole, the higher the degree of atomization of the fuel injected from the injection nozzle. Therefore, when such injection is performed, the fuel pressure in the nozzle hole is increased, and the injected fuel is appropriately atomized. Injecting fuel while operating the valve body in this way is also referred to as “full lift injection”.

  On the other hand, when a relatively small amount of fuel is injected within a relatively short time (for example, when performing so-called multistage injection), the valve body may be operated within a range where the lift amount does not become maximum. is there. In this case, the fuel pressure on the downstream side of the valve body (fuel pressure in the injection hole) decreases as the pressure loss due to the valve body increases as compared with the case where full lift injection is performed. As a result, the degree of atomization of the injected fuel may be lower than when full lift injection is performed. This fuel injection while operating the valve body is also referred to as “partial lift injection”.

  Even if the partial lift injection is performed, it is considered that the operation of the internal combustion engine is not substantially affected unless the degree of atomization of the fuel is significantly reduced. However, it is considered that if the degree of atomization of the fuel is excessively reduced, the internal combustion engine may not be operated properly when partial lift injection is performed.

  Therefore, when partial lift injection is performed, the fuel pressure at the injection into the injection nozzle (hereinafter also referred to as “injection fuel pressure”) is sufficiently increased in order to sufficiently increase the fuel pressure at the injection hole (hereinafter also referred to as “injection fuel pressure”). It is conceivable to raise the injection fuel pressure when full lift injection is performed. However, as can be understood from the above description, when the injection fuel pressure is increased, the force (the force in the direction of reducing the lift amount) for reducing the opening area exerted on the valve body also increases. Therefore, if the fuel pressure is inadvertently increased, the lift amount of the valve body does not increase sufficiently, the pressure loss due to the valve body increases, and the injection hole fuel pressure may possibly decrease. On the other hand, the higher the injection fuel pressure, the higher the fuel pressure on the upstream side of the valve body. Therefore, even if the pressure loss due to the valve body increases, the fuel pressure on the downstream side of the valve body (final injection hole fuel pressure) increases. There is also a possibility.

  In this way, considering the magnitude of the injected fuel pressure and the degree of pressure loss due to the valve body, etc., the injection hole fuel pressure may increase by increasing the injected fuel pressure, or the injection hole fuel pressure by increasing the injected fuel pressure. It is thought that there is a case where the value decreases. In other words, in partial lift injection, it can be concluded that fuel atomization is unconditionally promoted only by increasing the injection fuel pressure.

  In view of the above problems, an object of the present invention is to provide a control device for a fuel injection system that can appropriately atomize fuel injected from an injection nozzle even when partial lift injection is performed. is there.

A control device according to the present invention for solving the above-described problems is as follows.
An injection nozzle for injecting fuel, the injection nozzle having an injection hole through which the fuel is injected, a flow path for guiding the fuel toward the injection hole, and a valve body capable of adjusting an opening area of the flow path When,
Fuel pressure adjusting means capable of adjusting a fuel pressure which is a pressure of fuel injected into the injection nozzle;
Applied to a fuel injection system comprising:

  In the fuel injection system, the valve body is a force in a direction to expand the opening area and is generated according to an instruction to increase the opening area, and a force in a direction to reduce the opening area, and the fuel pressure is The opening area is adjusted by operating according to the resultant force of the force that increases as the value increases.

And the control apparatus by this invention is
When starting "partial lift injection" that injects the fuel while adjusting the opening area within a range between an intermediate value smaller than its maximum value and its minimum value,
An "average nozzle hole fuel pressure" that is an average value of the nozzle hole fuel pressure that is the pressure of the fuel in the nozzle hole during the period in which the fuel of the target fuel injection amount that is the target amount of fuel to be injected is injected,
“After the partial lift injection is started“ after ”the first average injection hole fuel pressure that would occur if the fuel of the target fuel injection amount was injected at the fuel pressure“ before ”the partial lift injection was started. The second average injection hole fuel pressure generated when the fuel of the target fuel injection amount is injected at the fuel pressure of “is large”
The opening area after the partial lift injection is started and the fuel pressure are controlled so as to satisfy the relationship between and.

  With the above configuration, the average value of the injection hole fuel pressure (the average value during the period from the start of fuel injection to the end of fuel injection) increases when partial lift injection is started. As a result, the average over the entire period during which fuel is injected, compared to the case where partial lift injection is performed while the injection fuel pressure remains “before” (ie, when full lift injection is being performed). Therefore, even if partial lift injection is started, the degree of fuel atomization is prevented from being lowered. That is, even when partial lift injection is performed, the fuel injected from the injection nozzle can be appropriately atomized.

  More specifically, as described above, a high injection fuel pressure does not necessarily mean that the injection hole fuel pressure is high (that is, the degree of fuel atomization is high). Therefore, if the injection fuel pressure is simply increased when starting partial lift injection, the degree of fuel atomization “after” the partial lift injection start is compared to the degree of fuel atomization “before” the partial lift injection start. It is considered that it cannot be surely prevented from falling.

  On the other hand, focusing on the nozzle hole fuel pressure, the average value (average nozzle hole fuel pressure) can be said to be one of the parameters expressing the history of the nozzle hole fuel pressure in the entire process of fuel injection. In other words, it can be said that the average injection hole fuel pressure is a parameter expressing the degree of atomization in the whole injected fuel. Therefore, it is considered that the higher the average injection hole fuel pressure, the higher the degree of atomization (average value of the degree of atomization) of the injected fuel as a whole. Therefore, if the opening area of the flow path and the fuel pressure are controlled so as to increase the average injection hole fuel pressure when partial lift injection is started, the fuel fine particles can be more reliably compared to the case where the injection fuel pressure is simply increased. Can be promoted.

  In addition, as understood from the above description, when the first average nozzle hole fuel pressure matches the maximum value of the second average nozzle hole fuel pressure (that is, the second average nozzle hole fuel pressure larger than the first average nozzle hole fuel pressure is In the case of non-existence), after the partial lift injection is started, the opening area of the flow path and the fuel pressure are controlled so that the fuel of the target fuel injection amount is injected with the fuel pressure “before” the partial lift injection is started. Just do it.

  By the way, the above-mentioned “average injection hole fuel pressure” can be obtained (estimated) by several methods before the partial lift injection is actually performed. The specific acquisition (estimation) method of the average nozzle hole fuel pressure, and the relationship between the opening area of the flow path and the magnitude of the average nozzle hole fuel pressure with respect to the injection fuel pressure will be described later (see, for example, Aspect 2).

  The “control device for the fuel injection system” according to the present invention controls the opening area of the flow path of the injection nozzle and the pressure of the fuel injected into the injection nozzle in consideration of the first average injection hole fuel pressure and the second average injection hole fuel pressure. A specific configuration and structure are not particularly limited as long as the configuration can be provided. For example, the control device obtains (estimates) the average injection hole fuel pressure, obtains information (target fuel injection amount, injection fuel pressure, etc.) necessary for the acquisition (estimation), the first average injection hole fuel pressure. Means for calculating (estimating) the opening area and the injection fuel pressure so that the second average nozzle hole fuel pressure becomes larger than the above, and the valve body of the injection nozzle so as to realize the calculated (estimated) opening area and the injection fuel pressure; It may be configured by means for issuing a signal for operating the fuel pressure adjusting means, and the like.

  The “fuel pressure in the nozzle hole” is a fuel pressure in a region around the nozzle hole and may be a fuel pressure within an appropriate range from the viewpoint of examining the degree of atomization of the fuel. For example, as the fuel pressure in the nozzle hole (injection hole fuel pressure), the pressure of the fuel at an arbitrary position in the flow path on the downstream side of the valve body, the pressure of the fuel when flowing into the nozzle hole, and the injected fuel pressure In other words, the fuel pressure in which the pressure loss due to the pressure is reduced, the fuel pressure in the vicinity of the nozzle hole, and the like.

  The fuel injection system to which the control device according to the present invention is applied is preferably applied to an internal combustion engine that directly injects fuel into the combustion chamber. For example, the fuel injection system to which the control device according to the present invention is applied can be provided for both a direct injection gasoline engine and a diesel engine.

  The configuration and effect of the control device of the present invention have been described above. Next, several modes (modes 1 and 2) of the control device of the present invention will be described below.

・ Mode 1
As described above, if the opening area of the flow path and the fuel pressure are controlled so that the second average nozzle hole fuel pressure is larger than the first average nozzle hole fuel pressure, the fuel can be appropriately atomized even if partial lift injection is started. Can be made. Furthermore, as understood from the above description, it is considered that the degree of fuel atomization can be further increased by increasing the second average nozzle hole fuel pressure as much as possible.

Therefore, the control device (mode 1) according to the present invention is:
The opening area after the partial lift injection is started and the fuel pressure may be controlled so that the second average injection hole fuel pressure matches the “maximum value”.

  The maximum value of the second average injection hole fuel pressure can be acquired (estimated) before actually performing the partial lift injection by a method similar to the method of acquiring (estimating) the average injection hole fuel pressure. A specific method for obtaining (estimating) the maximum value of the second average nozzle hole fuel pressure and a specific control method for the opening area of the flow path and the injection fuel pressure for making the second average nozzle hole fuel pressure coincide with the maximum value Will be described later (see, for example, Aspect 2).

  Hereinafter, an example (aspect 2) of obtaining (estimating) “average injection hole fuel pressure” before actually performing partial lift injection will be described.

・ Aspect 2
The injection hole fuel pressure is considered to correspond to a pressure loss caused by the valve body (which depends on the opening area of the flow channel) and a value obtained by subtracting the pressure loss caused by the flow channel itself from the injected fuel pressure. That is, it is considered that the nozzle hole fuel pressure is substantially determined based on the injection fuel pressure, the opening area of the flow path, and the shape of the flow path, except for various minor factors. Among these, the injection fuel pressure and the opening area of the flow path are variable parameters, and the shape of the flow path is determined according to the configuration and specifications of the injection nozzle, and thus can be regarded as an invariable parameter. Therefore, if the injection fuel pressure and the opening area of the flow path are determined, the nozzle hole fuel pressure is uniquely determined.

  In other words, the “relationship between the injection fuel pressure and the opening area of the flow path and the injection hole fuel pressure (hereinafter also referred to as“ first relationship ”)” is an inherent relationship determined for each injection nozzle. For example, the relationship can be specified in advance by conducting an experiment or the like in advance.

  On the other hand, it is considered that the amount of fuel injected from the injection nozzle per unit time is substantially determined based on the injection hole fuel pressure and the injection hole shape. Of these, the nozzle hole fuel pressure is a variable parameter, and the shape of the nozzle hole can be regarded as an invariant parameter. Therefore, if the injection hole fuel pressure is determined, the amount of fuel injected from the injection nozzle per unit time is uniquely determined.

  In other words, the “relationship between the injection hole fuel pressure and the amount of fuel injected per unit time from the injection nozzle (hereinafter also referred to as“ second relationship ”)” is also determined for each injection nozzle. For example, the relationship can be specified in advance by conducting an experiment or the like in advance.

  When fuel is injected from the injection nozzle, the opening area of the flow path gradually increases from zero to reach a predetermined value according to control by the control device, and then gradually decreases from the predetermined value to zero. (Hereinafter, the length of time that the opening area of the flow path changes in this way is also referred to as “fuel injection time”). This predetermined value corresponds to the maximum value of the opening area when full lift injection is performed, and corresponds to an intermediate value smaller than the maximum value when partial lift injection is performed. Such a change in the opening area is caused by the force (the above-mentioned resultant force) acting on the valve body of the injection nozzle.

  As described above, the force generated in accordance with the instruction to enlarge the opening area (force to increase the opening area) and the force that increases as the injection fuel pressure increases (direction to reduce the opening area) are applied to the valve body of the injection nozzle. Force). Therefore, if the force generated according to the instruction to enlarge the opening area is constant (fixed value) (usually a fixed value), the speed at which the valve body moves (speed at which the opening area increases or decreases. Will be determined according to the injected fuel pressure. Specifically, the greater the injected fuel pressure, the smaller the rate of increase in the opening area and the greater the rate of decrease. The smaller the injected fuel pressure, the greater the rate of increase in the opening area and the less rate of decrease. become. Therefore, if the injection fuel pressure is determined, the speed at which the opening area increases or decreases (temporal transition of the opening area) is uniquely determined.

  In other words, the “relationship between the injected fuel pressure and the temporal transition of the opening area of the flow path (hereinafter also referred to as“ third relationship ”)” can be determined in advance by conducting an experiment or the like in advance. Can be identified.

  According to the first relationship and the second relationship, if the injection fuel pressure and the opening area of the flow path are determined, the fuel injection amount per unit time is determined as a result. How to change the opening area of the flow path when it is desired to inject a predetermined amount of fuel at a predetermined injection fuel pressure (temporal transition of the opening area of the flow path, and hence the fuel injection time) I can grasp it.

  In other words, according to the first relationship, when the injection fuel pressure is constant (fixed value), the injection hole fuel pressure also changes according to the change in the opening area of the flow path. Furthermore, according to the second relationship, the fuel injection amount per unit time also changes according to the change in the nozzle hole fuel pressure. If the fuel injection amount per unit time is integrated over the fuel injection time determined in consideration of the third relationship, the total amount of fuel to be injected (fuel injection amount) is determined.

  Conversely, (Process 1) If the target fuel injection amount (target fuel injection amount) and the injected fuel pressure (fixed value) are given, the first to third relationships are considered, The “change in the opening area of the flow path (temporal transition)” necessary to achieve the target fuel injection amount can be determined. Further, (Process 2) If the temporal transition of the opening area of the flow path and the injected fuel pressure are applied to the first relationship, the “temporal transition of the injection hole fuel pressure” can be obtained (estimated). . (Process 3) From the temporal transition of the nozzle hole fuel pressure, an average nozzle hole fuel pressure that is an average value of the nozzle hole fuel pressure can be obtained (estimated). That is, by performing the processes in the order of (Process 1) to (Process 3), the average injection hole fuel pressure can be obtained (estimated) based on the target fuel injection amount and the injected fuel pressure.

Therefore, the control device (mode 2) according to the present invention is:
As the average nozzle hole fuel pressure,
The time of the opening area determined from the target fuel injection amount (obtained from the process 1) and the fuel pressure in the relationship (first relationship) acquired in advance among the opening area, the fuel pressure, and the nozzle hole fuel pressure. As well as the average value (by treatment 3) of the temporal transition of the nozzle hole fuel pressure obtained by applying the fuel transition, as well as the fuel pressure (as in treatment 2),
Can be configured to employ.

  According to the control device of this aspect, if the target fuel injection amount and the injected fuel pressure are given, the average injection hole fuel pressure is acquired (estimated in advance). Therefore, when the opening area of the flow path and the injected fuel pressure are controlled by the control device according to this aspect, the control device according to the present invention first determines the first average based on the target fuel injection amount and the fuel pressure “before” the partial lift injection start. The injection hole fuel pressure (the average injection hole fuel pressure when it is assumed that the injection is performed at the injection fuel pressure before the start of partial lift injection) is acquired. Furthermore, the control device of the present invention sequentially checks the average injection hole fuel pressure when different injection fuel pressures are applied to the same target fuel injection amount for each injection fuel pressure, so that the second average rather than the first average injection hole fuel pressure is obtained. The injection fuel pressure that satisfies the condition that the injection hole fuel pressure (average injection hole fuel pressure after the partial lift injection starts) increases is searched and specified. Then, after specifying the injection fuel pressure that satisfies this condition, the control device of this aspect opens the flow path so as to inject the fuel of the target fuel injection amount while controlling the injection fuel pressure to match the injection fuel pressure. Control the area.

  In addition, if the concept of the control device of this aspect (Aspect 2) is applied to the control apparatus of Aspect 1, the injection fuel pressure that satisfies the condition that the second average injection hole fuel pressure becomes maximum is searched and specified in the same manner as described above. You can also

  As described above together with some aspects, the control device of the present invention has an effect that fuel injected from the injection nozzle can be appropriately atomized even when partial lift injection is performed. Play.

1 is a schematic diagram of a fuel injection system to which a control device according to a first embodiment of the present invention is applied. It is the schematic of the injection nozzle which the fuel injection system of FIG. 1 has. It is the schematic showing the force which acts on the valve body of the injection nozzle of FIG. It is the flowchart which showed the routine which CPU of the control apparatus which concerns on the 1st Embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the control apparatus which concerns on the 1st Embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the control apparatus which concerns on the 1st Embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the control apparatus which concerns on the 2nd Embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the control apparatus which concerns on the 2nd Embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the control apparatus which concerns on other embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the control apparatus which concerns on other embodiment of this invention performs. It is the flowchart which showed the routine which CPU of the control apparatus which concerns on other embodiment of this invention performs.

  Hereinafter, each embodiment (1st Embodiment and 2nd Embodiment) of the fuel-injection control apparatus of the internal combustion engine by this invention is described, referring drawings.

<First Embodiment>
Outline of Device FIG. 1 shows a fuel injection system 10 to which a control device (hereinafter also referred to as “first device”) according to a first embodiment of the present invention is applied, and the fuel injection system 10. 1 shows a schematic configuration of an internal combustion engine 20 provided. The internal combustion engine 20 is a four-cycle, in-cylinder injection, spark ignition, multi-cylinder (four-cylinder) engine, and for convenience, only a cross section of one of the plurality of cylinders is shown in FIG.

  The fuel injection system 10 includes an injection nozzle 11 that injects fuel into a cylinder (inside the combustion chamber 25) of the internal combustion engine 20, a delivery pipe 12 that injects high-pressure fuel into the injection nozzle 11, and a high-pressure fuel that is delivered to the delivery pipe 12. A supply pump 13 that supplies fuel to the supply pump 13, and a delivery pipe pressure sensor 15 that measures the pressure of the fuel in the delivery pipe 12.

  The injection nozzle 11 is provided on the side surface of the cylinder so as to be able to inject fuel into the cylinder from the outer periphery of the cylinder (combustion chamber 25) (so-called side injection method). The delivery pipe 12 and the supply pump 13 are connected by a fuel supply path. The supply pump 13 pressurizes the fuel supplied from the fuel tank 14 to a fuel pressure according to the instruction and supplies the fuel to the delivery pipe 12. The delivery pipe 12 temporarily stores the fuel supplied from the supply pump 13 while maintaining the fuel pressure. Then, high-pressure fuel is injected from the delivery pipe 12 into the injection nozzle 11. When the fuel pressure in the delivery pipe 12 exceeds a predetermined maximum value, a part of the fuel is discharged from the pressure limit valve 12a and returned to the supply pump 13 or the fuel tank 14. As described above, the delivery pipe 12 and the supply pump 13 (and the fuel tank 14 in some cases) have a configuration capable of adjusting the pressure (fuel pressure) of the fuel injected into the injection nozzle 11.

  The injection nozzle 11 will be described in more detail below. FIG. 2 is a schematic diagram showing the structure of the injection nozzle 11. As shown in FIG. 2, the injection nozzle 11 has a nozzle hole 11a through which fuel is ejected, a channel 11b for guiding the fuel toward the nozzle hole 11a, and a valve body (needle) 11c. The injection hole 11a is one end of the injection nozzle 11 (the front end. Specifically, the end facing the combustion chamber 25 when the injection nozzle 11 is attached to the internal combustion engine 20. The end of the paper in the downward direction. ). The flow path 11b is a hollow portion that is formed inside the injection nozzle 11 and allows fuel to pass therethrough. The valve body 11c is a columnar member whose one end portion 11ca (end portion in the lower direction on the paper surface) is processed into a substantially conical shape, and along its axis (in a direction parallel to the major axis direction). It is supported in the injection nozzle 11 so as to be movable in the vertical direction of the drawing.

  The fuel is injected into the injection nozzle 11 from a fuel injection port 11d provided at the other end (upper end in the drawing) of the injection nozzle 11. As shown by the arrow in the figure, the fuel injected into the injection nozzle 11 passes through a passage provided inside the valve body 11c, and then along the valve body 11c, the tip of the injection nozzle 11 (below the paper surface). Head towards the end of the direction).

  Here, as shown in the partially enlarged view of FIG. 2, when the valve body 11 moves in the vertical direction of the paper (the mechanism of movement of the valve body 11c will be described later), the valve body tip 11ca and the flow The size of an area OS (area surrounded by a broken line in the figure) sandwiched between the inner wall surface 11ba of the path 11b changes. This area OS is a part of the flow path 11b, and changing the size of the area OS is synonymous with changing the opening area of the flow path 11b. Therefore, it can be said that the valve body 11c is a member which can adjust the opening area of the flow path 11b.

  The fuel that has passed through the region OS passes through the injection hole 11 a and is injected outside the injection nozzle 11. The entire path through which the fuel injected into the injection nozzle 11 passes through the injection hole 11a is the flow path 11b.

  Hereinafter, for the sake of convenience, the degree of opening of the flow path 11b by the valve body 11c (in other words, the distance between the distal end portion 11ca of the valve body 11c and the inner wall surface 11ba) is also referred to as the “lift amount” of the valve body 11c. It is called. The valve body 11c is moved away from the inner wall surface 11ba as much as possible from the position where the lift amount (opening area of the flow channel 11b) becomes zero by contacting the inner wall surface 11ba, thereby reducing the lift amount (opening area of the flow channel 11b). It is configured to be movable within the range up to the maximum position.

  In order to realize the movement of the valve body 11c as described above, the injection nozzle 11 includes a spring 11e that comes into contact with the other end portion (end portion in the upward direction of the paper) 11cb of the valve body 11c, and the electronic control device 40. It has a solenoid coil 11f that operates in response to an instruction. The spring 11e exerts an elastic force on the valve body 11c in a direction in which the lift amount decreases (downward in the drawing). On the other hand, the solenoid coil 11f applies an electromagnetic force in a direction (upward in the drawing) in which the lift amount increases to the valve body 11c. Furthermore, the end surface 11cc of the valve body 11c is in contact with the fuel injected from the fuel injection port 11d, and the end surface 11cc has a direction in which the lift amount decreases due to the pressure of the fuel (injection fuel pressure) (downward in the drawing). ) Power is exerted.

  The force exerted on the valve body 11c will be described in more detail below. FIG. 3 is a schematic diagram showing the force acting on the valve body 11c. As shown in FIG. 3, the valve body 11c includes an elastic force Fsp by a spring 11e, a force Ff resulting from fuel pressure (hereinafter also referred to as “fuel pressure Ff” for convenience), and a solenoid coil 11f. When in operation, an electromagnetic force Fsol is applied. Although it is considered that the fuel pressure Ffa is also exerted on the distal end portion 11ca of the valve body 11c, the area of the distal end portion 11ca is very small compared to the end surface 11cc, and therefore the fuel pressure Ffa exerted on the distal end portion 11ca is It is very small compared with the fuel pressure Ff exerted on 11 cc, and does not substantially affect the movement of the valve body 11c.

  Therefore, the valve body 11c moves in a direction corresponding to the resultant force of the elastic force Fsp, the fuel pressure Ff, and the electromagnetic force Fsol. Here, the magnitudes of the elastic force Fsp and the electromagnetic force Fsol take into consideration the injected fuel pressure (and the magnitude of the fuel pressure Ff resulting from the injected fuel pressure) determined from the viewpoint of appropriately injecting fuel into the combustion chamber 25. The valve body 11c is designed to be appropriately movable. Note that the elastic force Fsp and the electromagnetic force Fsol are generally designed to be regarded as constant (fixed values), and the fuel pressure Ff increases as the injected fuel pressure increases.

  Thus, the valve body 11c is a force that increases the lift amount and is generated according to an instruction to the solenoid coil 11f (electromagnetic force Fsol), and a force that decreases the lift amount and is injected. It is configured to move (activate) in accordance with the resultant force (fuel pressure Ff + elastic force Fsp) that increases as the fuel pressure increases.

  Referring to FIG. 1 again, the internal combustion engine 20 supplies air to the cylinder block portion (21 to 25), the cylinder head portion (31 to 38) fixed to the upper portion of the cylinder block portion, and the cylinder block portion (combustion chamber 25). Intake system (41 to 44) for supply, exhaust system (51 to 53) for releasing gas (exhaust gas) discharged from the cylinder block portion to the outside of the internal combustion engine 20, accelerator pedal (61), various sensors (71 to 78) and an electronic control unit (81 to 86).

  The cylinder block portion includes a cylinder 21, a piston 22, a connecting rod 23, and a crankshaft 24. The piston 22 reciprocates in the cylinder 21, and the reciprocating motion of the piston 22 is transmitted to the crankshaft 24 via the connecting rod 23, whereby the crankshaft 24 is rotated. The inner wall surface of the cylinder 21, the upper surface of the piston 22, and the lower surface of the cylinder head portion define a combustion chamber 25.

  A fuel injection nozzle 11 is provided on the side surface of the combustion chamber 25. The fuel injection nozzle 11 supplies an amount of fuel corresponding to the instruction (fuel injection amount) from the outer periphery of the combustion chamber 25 to the combustion chamber 25 at a timing corresponding to the instruction from the electronic control unit 81 (fuel injection timing). Injecting inward (so-called side injection method).

  The cylinder head includes an intake port 31 communicating with the combustion chamber 25, an intake valve 32 for opening and closing the intake port 31, an intake camshaft 33 for driving the intake valve 32, an exhaust port 34 communicating with the combustion chamber 25, and an exhaust port 34. An exhaust valve 35 that opens and closes, an exhaust camshaft 36 that drives the exhaust valve 35, an ignition plug 37, and an igniter 38 that generates a high voltage applied to the ignition plug 37 are provided.

  The intake system includes an intake manifold 41 that communicates with each cylinder via an intake port 31, an intake pipe 42 that is connected to a collective portion on the upstream side of the intake manifold 41, and an air cleaner 43 that is provided at an end of the intake pipe 42. And a throttle valve 44 that can change the opening area of the intake pipe 42, and a throttle valve actuator 44a that rotationally drives the throttle valve 44 in response to an instruction signal. The intake port 31, the intake manifold 41, and the intake pipe 42 constitute an intake passage.

  The exhaust system includes an exhaust manifold 51 communicated with each cylinder via an exhaust port 34, an exhaust pipe 52 connected to a downstream portion of the exhaust manifold 51, and exhaust gas purification provided in the exhaust pipe 52. A catalyst 53. The exhaust port 34, the exhaust manifold 51, and the exhaust pipe 52 constitute an exhaust passage.

  An accelerator pedal 61 for inputting an acceleration request and a required torque to the internal combustion engine 20 is provided outside the internal combustion engine 20. The accelerator pedal 61 is operated by an operator of the internal combustion engine 20.

  Further, as various sensors, the internal combustion engine 20 includes an intake air amount sensor 71, a throttle valve opening sensor 72, a cam position sensor 73, a crank position sensor 74, a water temperature sensor 75, air-fuel ratio sensors 76 and 77, and an accelerator opening. Sensor 78 is provided. As described above, the fuel injection system 10 includes the delivery pipe pressure sensor 15.

  The intake air amount sensor 71 is provided in the intake passage (intake pipe 42) and is configured to output a signal corresponding to the mass of air taken into the internal combustion engine 20 through the intake pipe 42.

  The throttle valve opening sensor 72 is provided near the throttle valve 44 and is configured to output a signal corresponding to the opening of the throttle valve 44.

  The cam position sensor 73 is provided in the vicinity of the intake camshaft 33 and is configured to output a signal corresponding to the rotational position of the intake camshaft 33.

  The crank position sensor 74 is provided in the vicinity of the crankshaft 24 and is configured to output a signal corresponding to the rotation of the crankshaft. Based on this signal, the rotational speed (engine rotational speed NE) of the crankshaft 24 per unit time is acquired.

  The water temperature sensor 75 is provided in the passage of the cooling water flowing through the cylinder 21, and is configured to output a signal corresponding to the temperature of the cooling water.

  The air-fuel ratio sensors 76 and 77 are provided in the exhaust passages upstream and downstream of the catalyst 53, and are configured to output signals corresponding to the exhaust gas introduced into the catalyst 53 and the air-fuel ratio of the exhaust gas discharged from the catalyst 53. Has been.

  The accelerator opening sensor 78 is provided in the accelerator pedal 61 and is configured to output a signal corresponding to the opening of the accelerator pedal 61. Based on this signal, the accelerator pedal opening degree Accp is acquired.

  The electronic control unit includes a CPU 81, a ROM 82 in which programs executed by the CPU 81, tables (maps), constants, and the like are stored in advance, a RAM 83 in which the CPU 81 temporarily stores data as necessary, and data in a state where power is turned on. It has a backup RAM 84 that holds the stored data while the power is shut off, and an interface 85. The CPU 81, ROM 82, RAM 83, RAM 44, and interface 85 are connected to each other via a bus.

  The interface 85 is connected to the various sensors described above and is configured to transmit signals output from the sensors to the CPU 81. Further, the interface 85 is connected to the injection nozzle 11 and the supply pump 13 and is configured to send an instruction signal to them in response to an instruction from the CPU 81.

  Specifically, the CPU 81 sends, via the interface 85, a signal related to the fuel injection timing, which is the timing at which fuel is injected from the injection nozzle 11, and an instruction signal related to the fuel injection amount, which is the amount of fuel injected from the injection nozzle 11. Then, it is configured to send to the injection nozzle 11 (or a control device that controls the operation of the injection nozzle 11). Further, for example, the CPU 81 sends an instruction signal related to the injected fuel pressure to the supply pump 13 (or a control device that controls the operation of the supply pump 13) in order to control the pressure of the fuel injected into the injection nozzle 11. It is configured.

  The above is the outline of the fuel injection system 10 to which the first device is applied and the internal combustion engine 20 including the fuel injection system 10.

-Operation | movement of an apparatus Hereinafter, the operation | movement of a 1st apparatus is demonstrated, referring FIGS. 4-6.
In the first device, the CPU 81 executes the routines shown in FIGS. 4 to 6 to determine and determine the fuel pressure (injection fuel pressure) and the opening area (lift amount) when the partial lift injection is started. The opening area (lift amount) of the flow path is controlled under a given fuel pressure (injection fuel pressure). Hereinafter, the cylinder where the partial lift injection is started is also referred to as a “fuel injection cylinder”.

  Specifically, first, the CPU 81 executes a “fuel injection control routine” shown in FIG. In this routine, the CPU 81 starts processing from step 400 at a predetermined timing, proceeds to step 410, and determines whether or not partial lift injection should be started at the present time. In this step, for example, the same determination is made based on the operating state of the internal combustion engine 20 determined from the engine speed NE and the accelerator pedal opening degree Accp.

  If partial lift injection should be started at the current time, the CPU 81 makes a “Yes” determination at step 410 and proceeds to step 420. In step 420, the CPU 81 determines a target fuel injection amount Qtgt. The target fuel injection amount Qtgt is set, for example, in a map set in advance so that an injection amount suitable for the operation of the engine 20 is determined, for example, the current operating state of the internal combustion engine 20 (for example, the engine speed NE and the accelerator pedal opening Accp). ) Is applied.

  Next, the CPU 81 proceeds to step 430. In step 430, the CPU 81 acquires the pressure (injection fuel pressure) Pfuel1 of the fuel currently injected into the injection nozzle 11 at the present time. The injected fuel pressure Pfuel1 is acquired based on a signal output from the delivery pipe pressure sensor 15.

  Next, the CPU 81 proceeds to step 440. In step 440, the CPU 81 estimates an average value of the injection hole fuel pressure (first average injection hole fuel pressure Phave1) when it is assumed that fuel of the target fuel injection amount Qtgt is injected at the injection fuel pressure Pfuel1. Specifically, in step 440, the CPU 81 executes an “average nozzle hole fuel pressure estimation routine” shown in FIG.

  In the routine shown in FIG. 5, when the CPU 81 starts processing from step 500, the process proceeds to step 510. In step 510, the CPU 81 estimates the lift transition over time L (t) based on the target fuel injection amount Qtgt and the injected fuel pressure Pfuel (in this process, the current injected fuel pressure Pfuel1).

  As described in the description of the aspect (aspect 2) of the control device of the present invention, when the injected fuel pressure is constant (fixed value), the target fuel injection amount and the injected fuel pressure are given as described above. Considering the first relationship to the third relationship, it is possible to determine the “time transition of the lift amount” necessary to achieve the target fuel injection amount. In the first device, the first relationship to the third relationship in the fuel injection system 10 are acquired in advance by experiments or the like. Therefore, by using these relationships, it is possible to estimate the temporal transition L (t) of the lift amount in this step.

  Next, the CPU 81 proceeds to step 520. In step 520, the CPU 81 changes the injection fuel pressure Pfuel1 and the lift amount at the present time to a relational expression FuncPih (Pfuel, L) in which “the relationship between the injection fuel pressure Pfuel, the lift amount L, and the nozzle hole fuel pressure Pih” is predetermined. The time transition Pih (t) of the nozzle hole fuel pressure is estimated by applying the time transition L (t). The relational expression in this step corresponds to the above-described first relation (see aspect 2).

  Next, the CPU 81 proceeds to step 530. In step 530, the CPU 81 calculates an average injection hole fuel pressure Pihave by averaging the temporal change Pih (t) of the injection hole fuel pressure over the fuel injection time (in this process, the first average injection hole fuel pressure Pihave1). Get as. Thereafter, the CPU 81 proceeds to step 595 and returns to step 440 in FIG.

  Referring to the routine of FIG. 4 again, the CPU 81 proceeds to step 450 after the processing of step 440 is completed. In step 450, the CPU 81 estimates an injection fuel pressure Pfuel2 at which a second average nozzle hole fuel pressure Phave2 greater than the first average nozzle hole fuel pressure Phave1 is obtained. Specifically, the CPU 81 executes a “fuel pressure search routine” shown in FIG.

  Specifically, when starting the process from step 600 in FIG. 6, the CPU 81 first executes a series of processes shown in steps 605 to 625. As a result of this series of processes, “the fuel pressure at which the second average injection hole fuel pressure Phave2 greater than the first average injection hole fuel pressure Pihave1 is obtained when the fuel pressure is gradually increased with reference to the current injected fuel pressure Pfuel1” exists. Whether or not there is such a fuel pressure, the fuel pressure is acquired as the injected fuel pressure Pfuel2.

  Specifically, in step 605, the CPU 81 stores the current injected fuel pressure Pfuel1 as a convenient value PF. The value PF is a value used for convenience to execute each process in this routine.

  Next, the CPU 81 proceeds to step 610. In step 610, the CPU 81 newly stores a value obtained by adding the increment ΔPfuel to the value PF in the value PF. That is, this step increases the value PF by the increment ΔPfuel.

  Next, the CPU 81 proceeds to step 615. In step 615, the CPU 81 determines whether or not the value PF is smaller than the maximum fuel pressure value Pfuelmax. The maximum value Pfuelmax of the fuel pressure is a value determined in advance depending on the configuration and specifications of the fuel injection system 10.

  If the current value PF is smaller than the maximum fuel pressure value Pfuelmax, the CPU 81 determines “Yes” in step 615 and proceeds to step 620. In step 620, the CPU 81 executes the routine of FIG. 5 to estimate the average injection hole fuel pressure Pihave2 when it is assumed that the target fuel injection amount Qtgt is injected when the fuel pressure is the current value PF.

  Next, the CPU 81 proceeds to step 625. In step 625, the CPU 81 determines whether or not the second average nozzle hole fuel pressure Pihave2 is larger than the first average nozzle hole fuel pressure Pihave1. In other words, in this step, it is determined whether or not the value PF corresponds to the injected fuel pressure Pfuel2 that satisfies the condition shown in step 450 of FIG.

  If the current second average nozzle hole fuel pressure Pihave2 is greater than the first average nozzle hole fuel pressure Pihave1, the CPU 81 makes a “Yes” determination at step 625 to proceed to step 630. In step 630, the CPU 81 stores the value PF in the average nozzle hole fuel pressure Pihave 2. Thereafter, the CPU 81 proceeds to step 695 and returns to step 450 in FIG.

  On the other hand, if the current second average nozzle hole fuel pressure Pihave2 is equal to or lower than the first average nozzle hole fuel pressure Pihave1, the CPU 81 makes a “No” determination at step 625 and returns to step 610. Then, the CPU 81 repeats the processing from step 610 to step 625 until it is determined as “Yes” in step 625. As a result, the value PF satisfying the condition (Pihave2> Pihave1) shown in step 450 is searched while the value PF is increased by increment ΔPfuel.

  In contrast, when the value PF reaches the maximum fuel pressure value Pfuelmax before the value PF satisfying the above condition is found (in other words, the value that satisfies the above condition until the value PF reaches the maximum fuel pressure value Pfuelmax). When the PF does not exist), the CPU 81 makes a “No” determination at step 615 to proceed to step 635.

  Then, the CPU 81 executes a series of processes shown in steps 635 to 655. By this series of processes, “the fuel pressure at which the second average injection hole fuel pressure Phave2 greater than the first average injection hole fuel pressure Phave1 is obtained when the fuel pressure is gradually reduced with reference to the current injected fuel pressure Pfuel1” exists. Whether or not there is such a fuel pressure, the same fuel pressure is acquired as the injected fuel pressure Pfuel2.

  Specifically, in step 635, the CPU 81 again stores the current injected fuel pressure Pfuel1 in the value PF for convenience.

  Next, the CPU 81 proceeds to step 640. In step 640, the CPU 81 stores the value obtained by subtracting the decrease ΔPfuel from the value PF as the value PF. That is, by this step, the magnitude of the value PF is reduced by the decrease ΔPfuel.

  Next, the CPU 81 proceeds to step 645. In step 645, the CPU 81 determines whether or not the value PF is larger than the minimum fuel pressure value Pfuelmin. The minimum value Pfuelmin of the fuel pressure is a value determined in advance depending on the configuration and specifications of the fuel injection system 10.

  If the current value PF is larger than the minimum fuel pressure value Pfuelmin, the CPU 81 makes a “Yes” determination at step 645 to proceed to step 650. In step 650, the CPU 81 estimates the average injection hole fuel pressure Pihave2 when it is assumed that the target fuel injection amount Qtgt is injected when the fuel pressure is the current value PF by executing the routine of FIG.

  Next, the CPU 81 proceeds to step 655. In step 655, the CPU 81 determines whether or not the second average nozzle hole fuel pressure Pihave2 is larger than the first average nozzle hole fuel pressure Pihave1. In other words, in this step, it is determined whether or not the value PF corresponds to the injected fuel pressure Pfuel2 that satisfies the condition shown in step 450 of FIG.

  If the current second average nozzle hole fuel pressure Pihave2 is larger than the first average nozzle hole fuel pressure Pihave1, the CPU 81 determines “Yes” in step 655 and proceeds to step 630. Then, the CPU 81 stores the value PF in the average injection hole fuel pressure Pihave2 in step 630, proceeds to step 695, and returns to step 450 in FIG.

  On the other hand, if the current second average nozzle hole fuel pressure Pihave2 is equal to or lower than the first average nozzle hole fuel pressure Pihave1, the CPU 81 makes a “No” determination at step 655 and returns to step 640. Then, the CPU 81 repeats the processing from step 640 to step 655 until it is determined as “Yes” in step 655. As a result, the value PF that satisfies the condition (Pihave2> Pihave1) shown in step 450 is searched while the value PF is decreased by the decrease ΔPfuel.

  However, when the value PF reaches the minimum fuel pressure value Pfuelmin before the value PF satisfying the above condition is found (in other words, the value PF that satisfies the above condition is reached before the value PF reaches the minimum fuel pressure value Pfuelmin). If it does not exist, that is, when it is confirmed that the maximum average nozzle hole fuel pressure Pihave2 is obtained by the current nozzle hole fuel pressure Pihave1, the CPU 81 makes a “No” determination at step 645 and proceeds to step 660. move on.

  In step 660, the CPU 81 stores the current injected fuel pressure Pfuel1 in the injected fuel pressure Pfuel2. Thereafter, the CPU 81 proceeds to step 695 and returns to step 450 in FIG.

  As described above, when the routine of FIG. 6 is executed, it is searched whether or not there is a fuel pressure at which a second average nozzle hole fuel pressure Phave2 greater than the first average nozzle hole fuel pressure Phave1 exists. If such a fuel pressure exists, the fuel pressure is adopted as the injected fuel pressure Pfuel2. On the other hand, if there is no such fuel pressure, the current injected fuel pressure Pfuel1 is adopted as the injected fuel pressure Pfuel2.

  Referring to the routine of FIG. 4 again, the CPU 81 proceeds to step 460 after the processing of step 450 is completed. In step 460, the CPU 81 controls the fuel injection system 10 so that the fuel pressure matches the injected fuel pressure Pfuel2. Specifically, an instruction is given to the supply pump 13 (or a control device that controls the operation of the supply pump 13) so that the fuel pressure matches the injected fuel pressure Pfuel2.

  Next, the CPU 81 proceeds to step 470. In step 470, the CPU 81 controls the lift amount so that the fuel of the target fuel injection amount Qtgt is injected from the injection nozzle 11 in the fuel injection cylinder. Specifically, the temporal transition of the lift amount is determined based on the same idea as in step 510 of FIG. 5, and the injection nozzle 11 (or the operation of the injection nozzle 11 is performed so that the lift amount changes according to the temporal transition. An instruction is given to a control device that controls

  Thereafter, the CPU 81 proceeds to step 495 to end the present routine tentatively.

  Thus, when starting the partial lift injection, the first device searches for the fuel pressure Pfuel2 that satisfies the condition that the first average nozzle hole fuel pressure is larger than the second average nozzle hole fuel pressure (Pihave2> Pihave1). The lift amount is controlled so that the fuel of the target fuel injection amount Qtgt is injected at the fuel pressure Pfuel2. As a result, the first device can appropriately atomize the fuel injected from the injection nozzle 11 even when partial lift injection is performed.

  The above is the description of the first embodiment of the present invention.

Second Embodiment
Next, a control device (hereinafter also referred to as “second device”) according to a second embodiment of the present invention will be described. The second device is applied to a fuel injection system having the same configuration as the fuel injection system 10 to which the first device is applied (hereinafter referred to as the “fuel injection system 10” as described above). Therefore, the description of the outline of the fuel injection system to which the second device is applied and the engine that provides the system is omitted.

-Operation of the device The second device is different from the first device in that "the lift amount and the fuel pressure are controlled so that the second average nozzle hole fuel pressure Pihave2 matches the maximum value".

  In the second device, the CPU 81 executes the routines shown in FIGS. 5, 7, and 8, and calculates the fuel pressure (injection fuel pressure) and the opening area (lift amount) of the flow path when starting the partial lift injection. The opening area (lift amount) of the flow path is controlled under a predetermined fuel pressure (injection fuel pressure).

  The routine shown in FIG. 7 differs from the routine shown in FIG. 4 only in that step 450 is replaced with step 710. The routine shown in FIG. 8 differs from the routine shown in FIG. 6 only in that steps 810 to 840 are provided instead of steps 625, 630, and 655. Therefore, steps for performing the same processing as the steps shown in FIGS. 4 and 6 in FIGS. 7 and 8 are denoted by the same reference numerals as those given to such steps in FIGS. . Detailed description of these steps will be omitted as appropriate.

  Specifically, when starting the process from step 700 of FIG. 7, the CPU 81 proceeds to step 710 after executing the processes of step 420 to step 440 if partial lift injection should be started at the present time. In step 710, the CPU 81 executes the “fuel pressure control routine” shown in FIG. 8, whereby the second average nozzle hole fuel pressure Pihave2 is larger than the first average nozzle hole fuel pressure Pihave1 and the second average nozzle hole fuel pressure is set. An injection fuel pressure Pfuel2 at which Pihave2 is maximized is estimated.

  In the routine shown in FIG. 8, when the CPU 81 starts processing from step 800, first, the CPU 81 executes a series of processing shown in steps 605 to 620 and step 810. By this series of processing, “the combination of each fuel pressure (value PF) when the fuel pressure is gradually increased with reference to the current injected fuel pressure Pfuel1 and the second average nozzle hole fuel pressure Phave2” is changed to the fuel pressure (value PF) is recorded until it reaches its maximum value Pfuelmax.

  Specifically, the CPU 81 proceeds to step 615 through step 605 and step 610, and determines whether or not the value PF is smaller than the maximum value Pfuelmax of the fuel pressure. If the current value PF is smaller than the maximum fuel pressure value Pfuelmax, the CPU 81 determines “Yes” in step 615 and proceeds to step 620. In step 620, the CPU 81 estimates the average injection hole fuel pressure Pihave2 when it is assumed that the target fuel injection amount Qtgt is injected when the fuel pressure is the value PF by executing the routine of FIG.

  Next, the CPU 81 proceeds to step 810. In step 810, the CPU 81 records the combination of the current value PF and the second average injection hole fuel pressure Phave2. This relationship is recorded in the RAM 83, for example.

  Thereafter, the CPU 81 returns to step 610 and repeats the processing of step 610 to step 810 until it is determined “No” in step 615. Thus, the combination of the value PF and the second average nozzle hole fuel pressure Pihave2 is continuously recorded until the value PF reaches the maximum value Pfuelmax.

  When the value PF reaches the maximum fuel pressure value Pfuelmax, the CPU 81 makes a “No” determination at step 615 to proceed to step 635.

  Then, the CPU 81 executes a series of processes shown in Steps 635 to 650 and Step 820. By this series of processing, “the combination of each fuel pressure (value PF) when the fuel pressure is gradually reduced with reference to the current injected fuel pressure Pfuel1 and the second average nozzle hole fuel pressure Phave2” is changed to the fuel pressure (value PF) is recorded until it reaches its minimum value Pfuelmin.

  Specifically, the CPU 81 proceeds to step 645 through step 635 and step 640, and determines whether or not the value PF is larger than the minimum value Pfuelmin of the fuel pressure. If the current value PF is larger than the minimum fuel pressure value Pfuelmin, the CPU 81 makes a “Yes” determination at step 645 to proceed to step 650. In step 650, the CPU 81 estimates the average injection hole fuel pressure Pihave2 when it is assumed that the target fuel injection amount Qtgt is injected when the fuel pressure is the value PF by executing the routine of FIG.

  Next, the CPU 81 proceeds to step 820. In step 820, the CPU 81 records the combination of the current value PF and the second average injection hole fuel pressure Phave2. This relationship is recorded in the RAM 83, for example.

  Thereafter, the CPU 81 returns to step 640 and repeats the processing from step 640 to step 820 until it is determined “No” in step 645. As a result, the combination of the value PF and the second average nozzle hole fuel pressure Pihave2 is continuously recorded until the value PF reaches the minimum value Pfuelmin.

  When the value PF reaches the minimum fuel pressure value Pfuelmin, the CPU 81 makes a “No” determination at step 645 to proceed to step 830.

  In step 830, the CPU 81 determines whether or not the maximum value of the second average injection hole fuel pressure Pihave2 recorded as described above is larger than the first average injection hole fuel pressure Pihave1. In other words, it is determined whether or not there is a value PF that satisfies the condition shown in step 710 (Pihave2> Pihave1 and Pihave2 is the maximum value).

  When the maximum value of the second average nozzle hole fuel pressure Pihave2 is larger than the first average nozzle hole fuel pressure Pihave1, the CPU 81 determines “Yes” in step 830 and proceeds to step 840. In step 840, the CPU 81 stores the value PF when the second average nozzle hole fuel pressure Phave2 is the maximum value in the injected fuel pressure Pfuel2.

  On the other hand, if the maximum value of the second average nozzle hole fuel pressure Pihave2 is equal to or less than the first average nozzle hole fuel pressure Pihave1, the CPU 81 makes a “No” determination at step 830 to proceed to step 660. In step 660, the CPU 81 stores the first average nozzle hole fuel pressure Pihave1 in the injected fuel pressure Pfuel2.

  After the value of the injected fuel pressure Pfuel2 is stored as described above, the CPU 81 proceeds to step 895 and returns to step 710 in FIG.

  As described above, when the routine of FIG. 8 is executed, the relationship between the injection fuel pressure (value PF) and the second average injection hole fuel pressure Pihave2 is recorded for each injection fuel pressure (value PF), and the second average injection hole fuel pressure Pihave2 is recorded. The injection fuel pressure at which the pressure becomes maximum is adopted as the injection fuel pressure Pfuel2. On the other hand, if there is no such injected fuel pressure, the current injected fuel pressure Pfuel1 is adopted as the injected fuel pressure Pfuel2.

  Referring to the routine of FIG. 7 again, the CPU 81 executes the processing of step 460 and step 470 after the processing of step 710 is completed. Thus, the lift amount is controlled so that the fuel of the target fuel injection amount Qtgt is injected from the injection nozzle 11 while the fuel pressure is controlled to coincide with the injection fuel pressure Pfuel2. Thereafter, the CPU 81 proceeds to step 495 to end the present routine tentatively.

  Thus, when the second device starts the partial lift injection, the second average nozzle hole fuel pressure is larger than the first average nozzle hole fuel pressure and the second average nozzle hole fuel pressure is maximum (Pihave2> Pihave1, Further, the fuel pressure Pfuel2 satisfying the condition of Pihave2 = maximum value) is searched, and the lift amount is controlled so that the fuel of the target fuel injection amount Qtgt is injected at the fuel pressure Pfuel2. As a result, the first device can appropriately atomize the fuel injected from the injection nozzle 11 even when partial lift injection is performed.

  The above is the description of the second embodiment of the present invention.

<Summary of Embodiment>
As described above, the control devices (first device and second device) according to the embodiment of the present invention are:
An injection nozzle 11 for injecting fuel, an injection hole 11a through which the fuel is injected, a flow path 11b for guiding the fuel toward the injection hole 11a, and a valve capable of adjusting an opening area of the flow path 11b An injection nozzle 11 having a body, and fuel pressure adjusting means (delivery pipe 12, supply pump 13) capable of adjusting a fuel pressure Pfuel which is a pressure of fuel injected into the injection nozzle 11,
The valve body 11c is a force in a direction to expand the opening area (region OS) and is generated according to an instruction to increase the opening area (lift amount) (electromagnetic force Fsol by the solenoid coil 11f), and the opening area The opening area is adjusted by operating according to the resultant force of the force that reduces the fuel pressure and increases as the fuel pressure Pfuel increases (fuel pressure Ff by the injected fuel pressure Pfuel + elastic force Fsp by the spring 11e). The control device applied to the fuel injection system configured as described above.

The control devices (first device and second device) according to the embodiment of the present invention are:
When partial lift injection for injecting the fuel is started while adjusting the opening area within a range between an intermediate value smaller than the maximum value and the minimum value (for example, in step 410 of FIG. Yes "),
The average injection hole fuel pressure Pihave, which is the average value of the injection hole fuel pressure Pih, which is the pressure of the fuel in the injection hole 11a during the period in which the fuel of the target fuel injection amount Qtgt, which is the target amount of fuel to be injected, is injected. The fuel pressure Pfuel2 after starting the partial lift injection is higher than the first average injection hole fuel pressure Pihave1 that would occur if fuel of the target fuel injection amount was injected at the fuel pressure Pfuel before starting lift injection. The opening area after the partial lift injection is started and the fuel pressure Pfuel are controlled so as to satisfy the relationship that the second average injection hole fuel pressure Phave2 generated when the fuel of the target fuel injection amount is injected is large. (For example, steps 450 to 470 in FIG. 4).

The control device (second device) according to the embodiment of the present invention is:
The opening area after the partial lift injection is started and the fuel pressure Pfuel are controlled so that the second average injection hole fuel pressure Pihave2 matches the maximum value (step 710 in FIG. 7). ).

The control devices (first device and second device) according to the embodiment of the present invention are:
As the average injection hole fuel pressure Phave, the relationship between the opening area L, the fuel pressure Pfuel, and the injection hole fuel pressure Phave is obtained in advance, and the time of the opening area determined from the target fuel injection amount and the fuel pressure Pfuel. The average value of the transition and the temporal transition of the fuel pressure Pfuel of the nozzle hole 11a obtained by applying the fuel pressure Pfuel is adopted (routine in FIG. 5).

<Other aspects>
The present invention is not limited to the above embodiments, and various modifications can be adopted within the scope of the present invention. For example, in the first device and the second device, the average injection hole fuel pressure is used as an index for determining the injected fuel pressure Pfuel2 after the partial lift injection is started. However, the control device of the present invention may be configured to use “a value corresponding to the average nozzle hole fuel pressure” as the index instead of the average nozzle hole fuel pressure.

  For example, the control device of this aspect (hereinafter also referred to as “other device”) multiplies “the opening area and the difference between the fuel pressure and the nozzle hole fuel pressure” as a value corresponding to the average nozzle hole fuel pressure. The value obtained by integrating the obtained value over the period during which the target fuel injection amount of fuel is injected can be employed. This value is also called “integrated injection hole fuel pressure”.

  More specifically, this aspect is different from the first apparatus in that the other apparatus adopts an average injection hole fuel pressure corresponding value instead of the average injection hole fuel pressure. If another device is applied to a fuel injection system having the same configuration as the fuel injection system 10 to which the first device is applied, the CPU 81 in the other device executes the routines shown in FIGS. The fuel pressure (injection fuel pressure) and the opening area (lift amount) of the flow path when executing partial lift injection are determined, and the opening area (lift amount) of the flow path is controlled under the predetermined fuel pressure (injection fuel pressure). To do.

  The routines shown in FIGS. 9 to 11 differ from the routines shown in FIGS. 4 to 6 only in that the processes in some steps are different from the routines shown in FIGS. Therefore, steps for performing the same processing as the steps shown in FIGS. 4 to 6 in FIGS. 9 to 11 are denoted by the same reference numerals as those given to such steps in FIGS. Has been. Detailed description of these steps will be omitted as appropriate.

  Specifically, when starting the process from step 900 of FIG. 9, the CPU 81 proceeds to step 910 via step 410 to step 430 when partial lift injection should be started at the present time. In step 910, the CPU 81 estimates a value corresponding to the average injection hole fuel pressure (first average injection hole fuel pressure corresponding value Pihco1) when it is assumed that the fuel of the target fuel injection amount Qtgt is injected at the injection fuel pressure Pfuel1. . Specifically, in step 910, the CPU 81 executes an “average injection hole fuel pressure corresponding value estimation routine” shown in FIG.

  Specifically, when starting the process from step 1000 in FIG. 10, the CPU 81 estimates a time transition L (t) of the lift amount at step 510 and proceeds to step 1010. In step 1010, the CPU 81 predetermines “a relationship between the injected fuel pressure Pfuel, the lift amount L, and the fuel pressure difference (differential pressure before and after the valve body) Pdif between the upstream side and the downstream side of the valve body 11 c” Further, the time transition Pdif (t) of the differential pressure before and after the valve body is estimated by applying the current fuel injection pressure Pfuel and the time transition L (t) of the lift amount to the table MapPdif (Pfuel, L).

  Next, the CPU 81 proceeds to step 1020. In step 1020, the CPU 81 calculates the product of the lift time transition L (t) and the pressure difference front and back pressure transition Pdif (t) as the target fuel injection amount Qtgt of fuel injection period. The value accumulated over (injection start time ts to injection end time te) is acquired as an average injection hole fuel pressure corresponding value Pihco (in this process, the first average injection hole fuel pressure corresponding value Pihco1). Thereafter, the CPU 81 proceeds to step 1095 and returns to step 910 in FIG.

  Referring to the routine of FIG. 9 again, the CPU 81 proceeds to step 920 after the processing of step 910 is completed. In step 920, the CPU 81 estimates an injection fuel pressure Pfuel2 that provides a second average nozzle hole fuel pressure corresponding value Pihco2 that is larger than the first average nozzle hole fuel pressure corresponding value Pihco1. Specifically, in step 920, the CPU 81 executes a “fuel pressure control routine” shown in FIG.

  Specifically, when starting the process from step 1100 in FIG. 11, the CPU 81 executes a series of processes shown in step 605 to step 615, step 1110 and step 1120. By this series of processing, “when the fuel pressure is gradually increased with reference to the current injected fuel pressure Pfuel1”, the fuel pressure at which the second average nozzle hole fuel pressure corresponding value Pihco2 larger than the first average nozzle hole fuel pressure corresponding value Pihco1 is obtained. It is confirmed (searched) whether or not “” exists, and when such a fuel pressure exists, the same fuel pressure is acquired as the injected fuel pressure Pfuel2.

  Specifically, the CPU 81 proceeds to step 615 through step 605 and step 610, and determines whether or not the value PF is smaller than the maximum value Pfuelmax of the fuel pressure. If the current value PF is smaller than the maximum fuel pressure value Pfuelmax, the CPU 81 determines “Yes” in step 615 and proceeds to step 1110. In step 1110, the CPU 81 executes the routine of FIG. 10 to estimate the average injection hole fuel pressure corresponding value Pihco2 when it is assumed that the target fuel injection amount Qtgt is injected when the fuel pressure is the value PF.

  Next, the CPU 81 proceeds to step 1120. In step 1120, the CPU 81 determines whether or not the second average nozzle hole fuel pressure corresponding value Pihco2 is larger than the first average nozzle hole fuel pressure corresponding value Pihco1.

  When the current second average nozzle hole fuel pressure corresponding value Pihco2 is larger than the first average nozzle hole fuel pressure corresponding value Pihco1, the CPU 81 makes a “Yes” determination at step 1120 to proceed to step 630. In step 630, the CPU 81 stores the value PF in the average injection hole fuel pressure corresponding value Pihco2, and then proceeds to step 1195 and returns to step 920 in FIG.

  On the other hand, if the current second average nozzle hole fuel pressure corresponding value Pihco2 is equal to or smaller than the first average nozzle hole fuel pressure corresponding value Pihco1, the CPU 81 makes a “No” determination at step 1120 and returns to step 610. Then, the CPU 81 repeats the processing of step 610, step 615, step 1110, and step 1120 until it determines “Yes” in step 1120. As a result, the value PF satisfying the condition of Pihave2> Pihave1 is searched while the value PF is increased by increment ΔPfuel.

  On the other hand, if the value PF reaches the maximum value Pfuelmax of the fuel pressure before the value PF satisfying the above condition is found, the CPU 81 makes a “No” determination at step 615 and proceeds to step 635.

  Then, the CPU 81 executes a series of processes shown in steps 635 to 645, step 1130, and step 1140. By this series of processing, “when the fuel pressure is gradually reduced with reference to the current injected fuel pressure Pfuel1”, the fuel pressure at which the second average nozzle hole fuel pressure corresponding value Pihco2 larger than the first average nozzle hole fuel pressure corresponding value Pihco1 is obtained. It is confirmed (searched) whether or not “” exists, and when such a fuel pressure exists, the same fuel pressure is acquired as the injected fuel pressure Pfuel2.

  Specifically, the CPU 81 proceeds to step 645 through step 635 and step 640, and determines whether or not the value PF is larger than the minimum value Pfuelmin of the fuel pressure. If the current value PF is larger than the minimum fuel pressure value Pfuelmin, the CPU 81 makes a “Yes” determination at step 645 to proceed to step 1130. In step 1130, the CPU 81 executes the routine of FIG. 10 to estimate the average injection hole fuel pressure corresponding value Pihco2 when the target fuel injection amount Qtgt is injected when the fuel pressure is the value PF.

  Next, the CPU 81 proceeds to step 1140. In step 1140, the CPU 81 determines whether or not the second average nozzle hole fuel pressure corresponding value Pihco2 is larger than the first average nozzle hole fuel pressure corresponding value Pihco1.

  If the current second average nozzle hole fuel pressure corresponding value Pihco2 is larger than the first average nozzle hole fuel pressure corresponding value Pihco1, the CPU 81 makes a “Yes” determination at step 1140 to proceed to step 1195 via step 630. Return to step 920 of step 9.

  On the other hand, if the current second average nozzle hole fuel pressure corresponding value Pihco2 is equal to or smaller than the first average nozzle hole fuel pressure corresponding value Pihco1, the CPU 81 makes a “No” determination at step 1140 and returns to step 640. The CPU 81 repeats the processing of step 640, step 645, step 1130, and step 1140 until it is determined as “Yes” in step 1140. As a result, the value PF that satisfies the condition of Pihave2> Pihave1 is searched for while the value PF is decreased by the decrease amount ΔPfuel.

  However, if the value PF reaches the minimum fuel pressure value Pfuelmin before the value PF satisfying the above condition is found, the CPU 81 makes a “No” determination at step 645 to proceed to step 660, where the current injected fuel pressure is reached. Pfuel1 is stored in the injected fuel pressure Pfuel2, the process proceeds to step 1195, and the process returns to step 920 in FIG.

  As described above, when the routine of FIG. 11 is executed, it is searched whether or not there is a fuel pressure at which the second average nozzle hole fuel pressure corresponding value Pihco2 larger than the first average nozzle hole fuel pressure corresponding value Pihco1 exists. If such a fuel pressure exists, the fuel pressure is adopted as the injection fuel pressure Pfuel2. On the other hand, if there is no such fuel pressure, the current injected fuel pressure Pfuel1 is adopted as the injected fuel pressure Pfuel2.

  Referring to the routine of FIG. 9 again, after the processing of step 920 is completed, the CPU 81 proceeds to step 460 to control the fuel injection system 10 so that the fuel pressure matches the injection fuel pressure Pfuel2, and proceeds to step 470 to reach the target. The lift amount is controlled so that fuel of the fuel injection amount Qtgt is injected from the injection nozzle 11. Thereafter, the CPU 81 proceeds to step 995 to end the present routine tentatively.

  As described above, the control device of the present invention can be configured to use the integrated injection hole fuel pressure instead of the average injection hole fuel pressure. The above is the description of another aspect of the present invention.

  Incidentally, in each of the above-described embodiments, the fuel injection system 10 to which the control device according to the present invention is applied is provided in an in-cylinder injection / spark ignition internal combustion engine 20 (so-called gasoline engine). However, as understood from the above description, the fuel injection system 10 to which the control device according to the present invention is applied can also be provided in an in-cylinder injection / self-ignition internal combustion engine (so-called diesel engine). That is, the control device according to the present invention can be applied to a gasoline engine or a diesel engine.

  The present invention can be used as a control device for a fuel injection system that can appropriately atomize fuel injected from an injection nozzle even when partial lift injection is performed.

DESCRIPTION OF SYMBOLS 10 ... Fuel injection system, 11 ... Injection nozzle, 11a ... Injection hole, 11b ... Flow path, 11c ... Valve body, 11d ... Fuel injection port, 11e ... Spring, 11f ... Solenoid coil, 12, 13 ... Fuel pressure adjustment means, 12 ... delivery pipe, 13 ... supply pump, 14 ... fuel tank

Claims (3)

An injection nozzle for injecting fuel, the injection nozzle having an injection hole through which the fuel is injected, a flow path for guiding the fuel toward the injection hole, and a valve body capable of adjusting an opening area of the flow path And a fuel pressure adjusting means capable of adjusting a fuel pressure that is a pressure of fuel injected into the injection nozzle, and
The force of the valve body in the direction to expand the opening area and generated according to the instruction to expand the opening area; and the force in the direction to reduce the opening area and the force that increases as the fuel pressure increases. A fuel injection system configured to adjust the opening area by operating according to the resultant force of
A control device applied to
When starting the partial lift injection that injects the fuel while adjusting the opening area within a range between an intermediate value smaller than the maximum value and the minimum value,
The average injection hole fuel pressure that is the average value of the injection hole fuel pressure that is the pressure of the fuel in the injection hole during the period in which the fuel of the target fuel injection amount that is the target amount of fuel to be injected is injected, starts the partial lift injection The fuel of the target fuel injection amount at the fuel pressure after starting the partial lift injection rather than the first average injection hole fuel pressure that would be generated if the fuel of the target fuel injection amount was injected at the fuel pressure before starting Controlling the opening area and the fuel pressure after starting the partial lift injection so as to satisfy the relationship that the second average injection hole fuel pressure generated when injecting
A control device for a fuel injection system configured as described above. The control device according to claim 1,
A control device configured to control the opening area and the fuel pressure after the partial lift injection is started so that the second average injection hole fuel pressure matches the maximum value. In the control device according to claim 1 or 2,
As the average injection hole fuel pressure, the temporal transition of the opening area determined from the target fuel injection amount and the fuel pressure, in the previously acquired relationship between the opening area and the fuel pressure and the injection hole fuel pressure, and A control device that employs an average value of temporal transition of the nozzle hole fuel pressure obtained by applying the fuel pressure.

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