JP2013124584A - Control device of internal combustion engine - Google Patents

Abstract

Power consumption and heat generation of an electronic control unit in a dual fuel injection internal combustion engine to which a precharge technology is applied are suppressed.
An in-cylinder fuel injection valve 25 for injecting and supplying fuel to a combustion chamber of an internal combustion engine, an intake port fuel injection valve 26 for injecting and supplying fuel toward an intake port, and a valve element in a coil of the fuel injection valve Precharge control means that precharges a smaller excitation current than the one that operates, and depending on the operating state of the internal combustion engine, only from the in-cylinder fuel injection valve, only from the intake port fuel injection valve, or from the in-cylinder fuel injection valve and intake air And a fuel switching control means for controlling the fuel to be switched and supplied at a predetermined injection ratio simultaneously from both the port fuel injection valve. When fuel is simultaneously injected from both the in-cylinder fuel injection valve and the intake port fuel injection valve, the precharge by the precharge control means is limited.
[Selection] Figure 1

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for a dual fuel injection internal combustion engine.

  2. Description of the Related Art Conventionally, an in-cylinder fuel injection valve that injects fuel into a cylinder of an internal combustion engine and an intake port fuel injection valve that injects fuel into an intake port are provided. 2. Description of the Related Art A so-called dual fuel injection type internal combustion engine is known in which a fuel injection valve and an intake port fuel injection valve are switched and used, or both are used by changing the injection ratio at the same time. Among these, for example, the one disclosed in Patent Document 1 includes an in-cylinder fuel injection valve that injects fuel into the combustion chamber, and an intake port fuel injection valve that injects fuel into the intake passage, and a fuel injection amount. When the fuel injection amount is equal to or less than the predetermined fuel injection amount, fuel is injected only from the in-cylinder fuel injection valve. When the fuel injection amount exceeds the predetermined fuel injection amount, the in-cylinder fuel injection valve and the intake port fuel injection valve Fuel is injected from both.

  Further, it is known that the valve opening delay varies due to the pressure, viscosity, etc. of the fuel existing in the fuel injection valve of the internal combustion engine, which causes an error in the injection amount. In response to such a problem, Patent Document 2 discloses a fuel injection valve that injects fuel by operating a valve body by supplying an excitation current to a coil of the fuel injection valve. An internal combustion engine that opens the valve body of the fuel injection valve with good responsiveness in various operating conditions and fuel properties by precharging the coil of the fuel injection valve with a smaller excitation current than that of the body. A fuel injection control device is disclosed.

Japanese Patent Laid-Open No. 3-105059 JP 2009-74373 A

  According to such a technology for precharging the coil of the fuel injection valve, the responsiveness at the time of opening the valve body is improved by energization (precharge) to the coil before the valve body of the fuel injection valve is opened. Thus, it is possible to eliminate the error factor of the injection amount and reduce the minimum injection amount that satisfies the linearity. However, when the precharge technology for the dual fuel injection type internal combustion engine described above is applied, for example, when injection is performed simultaneously from the in-cylinder fuel injection valve and the intake port fuel injection valve, the respective fuel injection valves However, since additional driving energy is required, there is a problem that power consumption (energy) of an electronic control unit including those control circuits increases and heat generation also increases. Therefore, there is room for further improvement when applying the precharge technology for the dual fuel injection internal combustion engine.

  The present invention has been made in view of the above point, and provides an internal combustion engine control device capable of suppressing power consumption and heat generation of an electronic control unit in a dual fuel injection internal combustion engine to which a precharge technology is applied. For the purpose.

  In order to achieve the above object, an embodiment of a control apparatus for an internal combustion engine according to the present invention includes an in-cylinder fuel injection valve that injects and supplies fuel to a combustion chamber of the internal combustion engine, and injects and supplies fuel toward an intake port. An intake port fuel injection valve, precharge control means for precharging an excitation current smaller than a valve element to act on the coil of the fuel injection valve, and the in-cylinder fuel injection valve in accordance with the operating state of the internal combustion engine Fuel that is controlled so as to switch and supply fuel at a predetermined injection ratio simultaneously only from the intake port fuel injection valve, or from both the in-cylinder fuel injection valve and the intake port fuel injection valve An internal combustion engine control device comprising: a switching control means, wherein when the fuel is injected simultaneously from both the in-cylinder fuel injection valve and the intake port fuel injection valve, And limits the precharge by the control means.

  Here, in the above aspect, when the linearity of the in-cylinder fuel injection valve is out of a predetermined range as a result of the injection ratio calculated by the fuel switching control means, fuel is supplied only from the intake port fuel injection valve. It is preferable to supply by injection.

  Further, in the above aspect, the apparatus further includes a temperature acquisition unit that estimates or measures the temperature of the electronic control unit constituting the control unit, and the precharge is performed when the temperature obtained by the temperature acquisition unit exceeds a predetermined value. It is preferable to limit the precharge by the control means.

  Here, the precharge used in the fuel injection valve in the present specification will be briefly described with reference to FIG. 2 in order to facilitate understanding of the present invention. Precharge is a fuel injection valve that injects fuel by operating the valve body by supplying an exciting current to the coil of the fuel injection valve, before the time when the valve body of the fuel injection valve is originally driven, An exciting current smaller than that in which the valve body of the fuel injection valve operates is caused to flow in the coil in advance. In FIG. 2A, the vertical axis represents the excitation current (i) and the horizontal axis represents the energization time (τ), and the hatched area portion a represents the drive energy by this precharge. In the same graph as FIG. 2A of FIG. 2B, the excitation current corresponding to FIG. 2A when the solid line is precharged, and the broken line is the case where the precharge is not performed The excitation current is shown. Further, FIG. 2C is a graph in which the vertical axis represents the injection amount (q) and the horizontal axis represents the energization time (τ). When the solid line is precharged, the broken line is not precharged. The injection amount of each is shown. As can be understood from FIGS. 2A and 2B, when the precharge is performed, the additional drive energy corresponding to the hatched area portion a is larger than when the precharge is not performed. is necessary. Further, as can be understood from FIG. 2C, when the precharge is performed, the responsiveness of the valve body is improved as compared with the case where the precharge is not performed. The injection amount qmin is also reduced. The term “precharge is limited” is used to mean that the excitation current is reduced or stopped.

  According to the above aspect, when fuel is simultaneously injected from both the in-cylinder fuel injection valve and the intake port fuel injection valve, the precharge by the precharge control means is limited. Therefore, since the precharge for the driving energy that has been additionally added to each fuel injection valve is limited, power consumption in the electronic control unit including those control circuits can be reduced accordingly. The heat generation can be suppressed.

It is a mimetic diagram showing one embodiment of a control device of an internal-combustion engine concerning the present invention. It is a graph explaining the relationship between the injection quantity characteristic by the presence or absence of precharge, and drive energy, (A) shows drive energy, (B) shows drive current, and (C) shows injection quantity. It is a flowchart which shows an example of the control procedure which the control apparatus of the internal combustion engine which concerns on this invention performs. It is a graph for demonstrating an example which determines injection ratio in one Embodiment of the control apparatus of the internal combustion engine which concerns on this invention. It is a graph which shows the drive energy according to the difference in the injection form. It is a flowchart which shows an example of the other control procedure which the control apparatus of the internal combustion engine which concerns on this invention performs.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram of an engine system 1 constituting a control device for an internal combustion engine according to the present invention, and only a part of the engine is shown.

  The engine system 1 includes an engine 100 that is a power source, and includes an electronic control unit (hereinafter referred to as ECU) 10 that comprehensively controls the operation of the engine 100. The engine 100 is a multi-cylinder engine mounted on a vehicle, and each cylinder includes a piston 11 constituting a combustion chamber 11a. The piston 11 in each combustion chamber is connected to a crankshaft 12 that is an output shaft via a connecting rod, and the reciprocating motion of the piston 11 is converted into rotation of the crankshaft 12 by the connecting rod.

  Connected to the combustion chamber 11a are an intake port 13 communicating with the combustion chamber 11a and an intake passage 14 connected to the intake port 13 and leading intake air from the intake port 13 to the combustion chamber 11a. Further, each cylinder of the combustion chamber 11a is connected to an exhaust port 15 communicating with the combustion chamber 11a and an exhaust passage 16 for guiding the exhaust gas generated in the combustion chamber 11a to the outside of the engine. Further, the exhaust passages 16 connected to the respective cylinders merge on the downstream side to form one merged exhaust passage 17.

  A plurality of intake valves and exhaust valves are provided for the combustion chamber 11a of each cylinder. FIG. 1 shows one intake passage, one exhaust passage and one intake valve, and one exhaust valve. An intake valve 18 is arranged in each intake port 13 of the combustion chamber 11a, and an intake camshaft 20 for opening and closing the intake valve 18 is arranged. Further, an exhaust valve 19 is disposed at each exhaust port 15 of the combustion chamber 11a, and an exhaust camshaft 21 for opening and closing the exhaust valve 19 is disposed.

  The intake valve 18 and the exhaust valve 19 are opened and closed by the rotation of the intake camshaft 20 and the exhaust camshaft 21 to which the rotation of the crankshaft 12 is transmitted by a coupling mechanism (for example, a timing belt, a timing chain, etc.). The port 15 and the combustion chamber 11a are communicated or blocked.

  The intake camshaft 20 has an electric VVT mechanism 22 that is a variable valve mechanism (hereinafter referred to as a VVT mechanism). The electric VVT mechanism 22 rotates the intake camshaft 20 with an electric motor in response to an instruction from the engine ECU 10. As a result, the rotational phase of the intake camshaft 20 relative to the crankshaft 12 is changed, so that the valve timing of the intake valve 18 is changed. In this case, the rotation phase of intake camshaft 20 is detected by intake cam angle sensor 32 and output to engine ECU 10. Thereby, the engine ECU 10 can acquire the phase of the intake camshaft 20 and the phase of the intake valve 18.

  The exhaust camshaft 21 has a hydraulic VVT mechanism 23. The hydraulic VVT mechanism 23 rotates the exhaust camshaft 21 with an oil control valve (hereinafter referred to as OCV) according to an instruction from the engine ECU 10. As a result, the rotational phase of the exhaust camshaft 21 relative to the crankshaft 12 is changed, so that the valve timing of the exhaust valve 19 is changed. In this case, the rotational phase of the exhaust camshaft 21 is detected by the exhaust cam angle sensor 33 and output to the engine ECU 10. Accordingly, the engine ECU 10 can acquire the phase of the exhaust camshaft 21 and can acquire the phase of the exhaust valve 19.

  The engine 100 includes an in-cylinder fuel injection valve 25 and an intake port fuel injection valve 26 in the combustion chamber 11a and the intake port 13, respectively. Further, the combustion chamber 11a of each cylinder is provided with a spark plug 27, and the ignition timing of the spark plug 27 is adjusted by an igniter 28.

  When the exhaust valve 19 is opened, the exhaust gas after combustion merges in the merged exhaust passage 17 through the exhaust port 15 and the exhaust passage 16, passes through the purification catalyst 29, and is discharged to the outside of the engine 100. The purification catalyst 29 is used to purify the exhaust gas of the engine 100. For example, a three-way catalyst or a NOx occlusion reduction type catalyst is applied. A plurality of the purification catalysts 29 may be used in combination depending on the displacement of the engine 100, the use area, and the like. The combined exhaust passage 17 is provided with an exhaust temperature sensor 36, an A / F sensor 37, and an O2 sensor 38, which detects the temperature and air-fuel ratio of the exhaust gas discharged from the combustion chamber 11a, and sends the results to the engine ECU 10. And send. Further, the purification catalyst 29 is provided with a catalyst temperature sensor 40, which detects the temperature of the purification catalyst 29 and transmits the result to the engine ECU 10.

  A crank angle sensor 31 is provided in the vicinity of the crankshaft 12. The crank angle sensor 31 is configured to detect the rotation angle of the crankshaft 12, and transmits the detection result to the engine ECU 10. Thereby, engine ECU10 acquires the information regarding a crank angle, such as the engine speed at the time of a driving | operation, and rotation angular velocity.

  Further, an air flow meter 34, a throttle valve 24, and a throttle position sensor 35 are installed in the intake passage 14 of the engine 100. The air flow meter 34 and the throttle position sensor 35 detect the amount of intake air passing through the intake passage 14 and the opening of the throttle valve 24, respectively, and transmit the detection results to the engine ECU 10. The engine ECU 10 recognizes the intake air amount introduced into the intake port 13 and the combustion chamber 11a based on the transmitted detection result, and adjusts the opening degree of the throttle valve 24 to thereby adjust the intake air necessary for the operation of the engine 100. Is taken into the combustion chamber 11a.

  The in-cylinder fuel injection valve 25 mounted in the combustion chamber 11a is supplied with fuel through a fuel pipe by a high-pressure fuel pump 30, and is injected and supplied to the combustion chamber 11a in the cylinder according to an instruction from the engine ECU 10. The intake port fuel injection valve 26 mounted on the intake port 13 is supplied with fuel through a fuel pipe by a low-pressure fuel pump (not shown), and is injected and supplied to the intake port 13 in accordance with an instruction from the engine ECU 10.

  A fuel pressure sensor 41 is provided in the fuel piping of the in-cylinder fuel injection valve 25. The fuel pressure sensor 41 detects the pressure of the fuel supplied to the in-cylinder fuel injection valve 25 and transmits the detection result to the engine ECU 10. The engine ECU 10 recognizes the pressure of the fuel supplied to the in-cylinder fuel injection valve 25 based on the transmitted detection result. The fuel pressure sensor 41 can be provided at any part capable of detecting the pressure of the fuel supplied to the in-cylinder fuel injection valve 25 regardless of the fuel piping.

  The engine ECU 10 includes a microcomputer that includes a CPU that performs arithmetic processing, a ROM that stores programs and the like, and a RAM that stores data and the like. The engine ECU 10 reads the detection results of a crank angle sensor 31, an intake cam angle sensor 32, an air flow meter 34, a throttle position sensor 35, an exhaust temperature sensor 36, a water temperature sensor 39, an unillustrated oil temperature sensor, etc. The operation operation of the engine 100 is integratedly controlled such as the operation, the operation of the intake valve 18 and the exhaust valve 19, the operation of the in-cylinder fuel injection valve 25 and the intake port fuel injection valve 26, and the ignition timing of the spark plug 27.

  Note that in the engine 100 according to the present embodiment, only fuel injection from the in-cylinder fuel injection valve 25 (hereinafter referred to as direct injection), fuel injection from the intake port fuel injection valve 26, based on the operating state of the engine 100. (Hereinafter referred to as PFI injection) only, or simultaneous fuel injection from the in-cylinder fuel injection valve 25 and the intake port fuel injection valve 26 at a predetermined injection ratio is switched. That is, when the fuel is directly injected into the combustion chamber 11a by the in-cylinder fuel injection valve 25 when the engine 100 is in a cold operating state, the fuel evaporability is poor and the liquid fuel is likely to adhere to the combustion chamber wall surface. Therefore, soot and smoke are easily generated and oil is easily diluted, so PFI injection is executed. Conversely, during a warm period (warming-up completion) where such a problem does not occur, only direct injection is performed, and output priority control of the engine 100 is executed. And when performing direct injection and PFI injection simultaneously, as explained below, the injection ratio is changed according to the situation in the middle of the process.

  That is, the injection ratio of the in-cylinder fuel injection valve 25 and the intake port fuel injection valve 26 is set to an appropriate value based on, for example, the graph shown in FIG. In the following description, the injection from the in-cylinder fuel injection valve 25 will be referred to as an injection ratio α (%). In this case, the injection ratio of the intake port fuel injection valve 26 is (100−α) (%). In this embodiment, it is determined based on the engine cooling water temperature or oil temperature (hereinafter referred to as water temperature) T (° C.), and when the water temperature T is lower than the predetermined first temperature T1, the intake air Fuel is supplied only from the port fuel injection valve 26. In other words, the injection ratio α from the in-cylinder fuel injection valve 25 is 0%. On the other hand, when the water temperature T is higher than a predetermined second temperature T2 higher than the first temperature T1, fuel is injected and supplied only from the in-cylinder fuel injection valve 25. In other words, the injection ratio α from the in-cylinder fuel injection valve 25 is 100%. When the water temperature T is between the first temperature T1 and the second temperature T2, the fuel is injected and supplied simultaneously from the in-cylinder fuel injection valve 25 and the intake port fuel injection valve 26. The injection ratio α from the in-cylinder fuel injection valve 25 is calculated by the following equation. That is, α = (T−T1) / (T2−T1) × 100 (%). The injection ratio α may be set to an appropriate value obtained in advance by a bench test or the like and stored in advance in the ROM of the engine ECU 10.

  Here, the operation of the engine system 1 will be described along the flow of control of the engine ECU 10. FIG. 3 is a flowchart showing an example of a control routine executed by the engine ECU 10. The control of the engine ECU 10 starts when the engine 100 is requested to start, that is, when the ignition switch is turned on, and the following control is repeated at a predetermined cycle until the engine 100 is requested to stop.

  First, when control is started, the engine ECU 10 acquires engine operating state information in step S301. Specifically, the detection results of the crank angle sensor 31, the air flow meter 34, the throttle position sensor 35, the water temperature (or oil temperature) sensor 39, etc. are read to obtain data information on the engine speed, load, and water temperature T. Then, the process proceeds to the next step S302, and based on the data information, it is determined whether or not the engine state is such that fuel is simultaneously injected from the in-cylinder fuel injector 25 and the intake port fuel injector 26. If the result of determination in step S <b> 302 is not simultaneous injection, this control routine is once terminated. On the other hand, when it is simultaneous injection, the process proceeds to the next step S303.

  In step S303, the engine ECU 10 calculates the injection ratio α based on the respective data information acquired in step S301. Further, the engine ECU 10 calculates the fuel injection amounts from the in-cylinder fuel injection valve 25 and the intake port fuel injection valve 26 based on the respective injection ratios α calculated in step S303. Then, the engine ECU 10 proceeds to step S304, and stops precharging the in-cylinder fuel injection valve 25 and the intake port fuel injection valve 26.

  In this embodiment, the effect as shown in the graph of FIG. 5 is obtained by stopping the precharge. That is, FIG. 5 is a graph showing the fuel injection valve drive energy according to the difference in the injection mode at a predetermined engine speed, 100% direct injection with precharge on the left side, and direct injection with precharge in the center + The driving energy in the PFI injection and the direct injection + PFI injection in which the precharge is stopped on the right side is shown in black for the direct injection and in white for the PFI injection. A difference in drive energy caused by the presence or absence of precharge is indicated by β. As is clear from this, the fuel injection valve drive energy for β can be reduced by stopping the precharge.

  Furthermore, in the present embodiment, the process proceeds to step S305, and the fuel injection amount from the in-cylinder fuel injection valve 25 set based on the injection ratio α calculated in step S303 is the value of the in-cylinder fuel injection valve 25. It is determined whether the linearity is within an allowable range. In other words, it is determined whether or not the fuel injection amount q set based on the injection ratio α exceeds the minimum injection amount qmin of the in-cylinder fuel injection valve 25. If the result of determination in step S305 is that the linearity is within the allowable range, this control routine is once terminated. On the other hand, when the linearity is not within the allowable range, the process proceeds to the next step S306. In step S306, the fuel injection amount from the in-cylinder fuel injection valve 25 that was the injection ratio α is eliminated, in other words, the injection ratio α from the in-cylinder fuel injection valve 25 is set to zero, and the intake port fuel The injection ratio (100−α) from the injection valve 26 is set to 100%.

  Next, another embodiment of the present invention will be described with reference to the flowchart of FIG. 6 showing a control routine executed by the engine ECU 10.

  First, when control is started, the engine ECU 10 acquires temperature information of the ECU 10 in step S601. Specifically, it is a measured temperature value t measured by a temperature sensor (not shown) provided in the casing of the ECU 10, for example. The temperature value t may be an estimated value based on the usage history of the engine ECU 10 or the like. Then, the process proceeds to the next step S602, where it is determined whether or not the temperature value t is within the allowable temperature range of the ECU 10. If the result of determination in step S602 is that the temperature is within the allowable temperature range, this control routine is once terminated. On the other hand, when the temperature is not within the allowable temperature range, the process proceeds to the next step S303, and the precharge for the in-cylinder fuel injection valve 25 and the intake port fuel injection valve 26 is stopped.

  In the present embodiment, the process further proceeds to step S604, and the temperature information of the ECU 10 is acquired again. Then, the process proceeds to the next step S605, and it is determined again whether or not the temperature value t after the stop of the precharge is within the allowable temperature range of the ECU 10. If the result of determination in step S605 is that it is within the allowable temperature range, this control routine is once terminated. On the other hand, when the temperature is not within the allowable temperature range, the process proceeds to the next step S606, where the fuel injection amount from the in-cylinder fuel injection valve 25 that was the injection ratio α is eliminated, in other words, the injection from the in-cylinder fuel injection valve 25. The division ratio α is set to zero, and the injection division ratio (100−α) from the intake port fuel injection valve 26 is changed to 100%, in other words, PFI 100% injection.

  In addition, said embodiment is only an example for implementing this invention. Therefore, the present invention is not limited to these, and it goes without saying that various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

10 Electronic control unit (ECU)
11a Combustion chamber (inside cylinder)
25 In-cylinder fuel injection valve 26 Intake port fuel injection valve

Claims (3)

An in-cylinder fuel injection valve that injects fuel into the combustion chamber of the internal combustion engine, an intake port fuel injection valve that injects fuel toward the intake port, and a valve body smaller than the valve body that operates on the coil of the fuel injection valve Precharge control means for precharging excitation current, and only from the in-cylinder fuel injection valve, only from the intake port fuel injection valve, or from the in-cylinder fuel injection valve and the intake air depending on the operating state of the internal combustion engine A control device for an internal combustion engine, comprising: a fuel switching control means for controlling the fuel to be switched and supplied at a predetermined injection ratio simultaneously from both of the port fuel injection valve,
A control apparatus for an internal combustion engine, wherein the precharge by the precharge control means is restricted when fuel is simultaneously injected from both the in-cylinder fuel injection valve and the intake port fuel injection valve.   As a result of the injection ratio calculated by the fuel switching control means, when the in-cylinder fuel injection valve nonlinearity is outside a predetermined range, fuel is injected and supplied only from the intake port fuel injection valve. The control apparatus for an internal combustion engine according to claim 1.   The apparatus further comprises temperature acquisition means for estimating or measuring the temperature of the ECU constituting the control means, and restricts precharge by the precharge control means when the temperature obtained by the temperature acquisition means exceeds a predetermined value. 3. The control apparatus for an internal combustion engine according to claim 1, wherein the control apparatus is an internal combustion engine.

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