WO2019181293A1

WO2019181293A1 - Internal combustion engine control device

Info

Publication number: WO2019181293A1
Application number: PCT/JP2019/005215
Authority: WO
Inventors: 一浩押領司; 赤城　好彦; 秀文岩城
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2018-03-20
Filing date: 2019-02-14
Publication date: 2019-09-26
Also published as: JP2019163745A; JP6908548B2

Abstract

Provided is an internal combustion engine control device that favorably ignites an air-fuel mixture to improve ignition performance and fuel performance. The internal combustion engine control device controls an internal combustion engine provided with an ignition coil and an ignition plug and is provided with: a target supply energy calculation unit that calculates an energy amount required to ignite an air-fuel mixture supplied to a combustion chamber of the internal combustion engine on the basis of an operation condition of the internal combustion engine or a physical quantity related to ignition of the ignition plug; a current waveform generation unit that generates, in accordance with the energy amount, current waveform data related to the waveform of a current supplied to the ignition plug; and a power control unit that controls power supplied to the ignition plug in accordance with the current waveform data.

Description

Internal combustion engine control device

The present invention relates to a control device for an internal combustion engine mounted on a vehicle or the like, and particularly to a control device for an internal combustion engine having an ignition function for igniting an air-fuel mixture formed in a combustion chamber.

From the viewpoint of environmental conservation and effective use of resources, further improvements in automobile efficiency and exhaust purification are required. As means for improving the efficiency, there are a high compression ratio and downsizing of the internal combustion engine. In an internal combustion engine with a high compression ratio and downsizing, the pressure in the combustion chamber rises and the air-fuel mixture becomes hot, and abnormal combustion is likely to occur. Therefore, variable compression ratio control with variable compression ratio, exhaust circulation combustion control (EGR) that recirculates exhaust gas to suppress abnormal combustion, or lean combustion control that leans the air-fuel mixture in the cylinder and burns it. Tend to be applied. A plurality of these control methods may be used in combination in a single internal combustion engine.

∙ From the viewpoint of exhaust purification, it is important to take measures against this misfire phenomenon because the failure of ignition of the air-fuel mixture and the occurrence of a misfire phenomenon adversely affects the exhaust purification. For example, it is known that the discharge generated in the spark plug is blown out by the flow of the air-fuel mixture in the cylinder, thereby causing a misfire phenomenon. In an internal combustion engine to which the above-described EGR control or lean combustion control is applied, the pressure variation in the combustion chamber is large and the change in the air flow in the combustion chamber is also large, so that a countermeasure against the misfire phenomenon is particularly important.

In order to suppress the misfire phenomenon, for example, Patent Document 1 discloses a technique for appropriately setting the sustaining current of the spark plug based on the operating conditions of the internal combustion engine. However, the technique of Patent Document 1 sets a maintenance current mainly according to the flow rate of the air-fuel mixture, and is not sufficient for improving the ignition performance.

JP 2017-2791 A

An object of the present invention is to provide a control device for an internal combustion engine that improves ignition performance and fuel consumption performance by igniting an air-fuel mixture satisfactorily.

An internal combustion engine control apparatus according to a first aspect of the present invention is an internal combustion engine control apparatus that controls an internal combustion engine that includes an ignition coil and an ignition plug, and is related to an operating condition of the internal combustion engine or ignition of the ignition plug. A target supply energy calculation unit that calculates the amount of energy required for ignition of the air-fuel mixture supplied to the combustion chamber of the internal combustion engine based on a physical quantity, and a current related to a waveform of a current supplied to the spark plug according to the energy amount A current waveform generation unit configured to generate waveform data; and a power control unit configured to control power supplied to the spark plug according to the current waveform data.
An internal combustion engine control apparatus according to a second aspect of the present invention is an internal combustion engine control apparatus that controls an internal combustion engine that includes an ignition coil and an ignition plug. An energy calculation unit that calculates an amount of energy required for ignition of the air-fuel mixture supplied to the combustion chamber of the internal combustion engine based on a related physical quantity, and supplies the spark plug according to a calculation result of the energy calculation unit A current waveform generation unit that generates current waveform data relating to a current waveform, and a power control unit that controls power supplied to the spark plug according to the current waveform data. The current waveform generator includes an initial current, a sustain current larger than the initial current, and a current change rate indicating a degree of change per unit time of the current between the initial current and the sustain current. Set.

According to the present invention, it is possible to provide a control device for an internal combustion engine that improves the ignition performance and fuel consumption performance by favorably igniting the air-fuel mixture.

It is a block diagram which shows the basic composition of the internal combustion engine provided with the fuel-injection control apparatus which concerns on 1st Embodiment. 2 is a functional block diagram showing a configuration of an ECU 200. FIG. 3 is a block diagram illustrating an example of a more detailed configuration of a current waveform generation unit 207. FIG. It is a graph explaining the significance of setting the optimal current change rate _Rcc . It is a graph which shows the difference of the characteristic of the current pulse which has different current change rate _Rcc . FIG. 3 is a schematic view showing discharge between both electrodes of a spark plug 105. 6 is a conceptual diagram illustrating an example of a method (operation) for setting a target supply energy E _tar in a target supply energy setting unit 206. FIG. The relationship between the initial current i _ini and the amount of expansion of the discharge path of the spark plug 105 when the flow rate of the air-fuel mixture around the spark plug 105 is a predetermined value is shown. The example of the waveform of the secondary current and secondary voltage of the secondary side coil (not shown) of the ignition coil 106 is shown. It is a graph which shows the relationship between the discharge path followable | trackability C and another factor. The method of calculation of heating duration Delta] t _R in the heating duration calculation unit 2073 is a schematic view illustrating the. It is a schematic view for explaining a method of setting the current change rate R _cc at a current change rate setting unit 2074 (operation). 10 is a flowchart illustrating a correction procedure in a correction unit 2075. It is a graph explaining the example of the current pulse waveform data and discharge current by 1st Embodiment. It is a graph explaining the example of the current pulse waveform data and discharge current by 1st Embodiment. It is a graph explaining the example of the current pulse waveform data and discharge current by 1st Embodiment. It is the schematic explaining 2nd Embodiment. It is the schematic explaining 3rd Embodiment.

Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may be denoted by the same numbers. Note that the attached drawings show an embodiment and an implementation example according to the principle of the present disclosure, but these are for the purpose of understanding the present disclosure, and are never used to interpret the present disclosure in a limited manner. It is not a thing. The descriptions in this specification are merely exemplary, and are not intended to limit the scope of the claims or the application in any way whatsoever.

This embodiment has been described in sufficient detail for those skilled in the art to practice the present disclosure, but other implementations and configurations are possible and depart from the scope and spirit of the technical idea of the present disclosure. It is necessary to understand that the configuration and structure can be changed and various elements can be replaced. Therefore, the following description should not be interpreted as being limited to this.

[First Embodiment]
FIG. 1 shows a basic configuration of an internal combustion engine provided with a fuel injection control device according to a first embodiment of the present invention.

<Basic configuration>
As shown in FIG. 1, an internal combustion engine 100 as a control target of the first embodiment is controlled by an ECU 200 as a fuel injection control device and an accelerator opening sensor 300 that detects an accelerator opening.
The internal combustion engine 100 includes a piston 101, an intake valve 102, and an exhaust valve 103 in a cylinder. As an example, the internal combustion engine 100 can be an internal combustion engine having a plurality of, for example, four cylinders, but FIG. 1 representatively shows only one of the plurality of cylinders. .
The piston 101 is connected to a crankshaft (not shown). The crankshaft is composed of a main shaft and a subshaft, and the subshaft is connected to the piston 101 via a connecting rod. Here, a variable compression ratio mechanism may be provided in which the distance between the main shaft and the sub shaft or the length of the connecting rod is variable. By providing this variable compression ratio mechanism, it is possible to change the stroke amount of the piston, thereby making the pressure in the combustion chamber variable.

The cylinder head is provided with an ignition plug 105 and an ignition coil 106. Further, the cylinder head is provided with a fuel injection valve 107 that directly injects fuel into the combustion chamber in the cylinder. Although not shown, the water jacket of the cylinder may be provided with a coolant temperature sensor.

An intake pipe 110 for introducing air sucked into the internal combustion engine 100 is provided upstream of the intake valve 102, and exhaust gas discharged from the cylinder is discharged downstream of the exhaust valve 103. An exhaust pipe 111 is provided.
The intake pipe 110 includes an intercooler 112 that cools the intake air, a throttle valve 113 that adjusts the intake air amount according to the accelerator opening, a surge tank 114 that adjusts the flow of intake air, and a part of the intake passage that is narrowed. A tumble control valve (TCV) 115 is provided for generating turbulence (tumble) in the intake air flow.
The exhaust pipe 111 communicates with an exhaust passage 121, and a three-way catalyst 123, an air-fuel ratio sensor 124, and a turbine 125b are provided in the exhaust passage 121. The three-way catalyst 123 is for purifying the exhaust gas, and the air-fuel ratio sensor 124 is a sensor for detecting the air-fuel ratio of the exhaust gas. Further, the turbine 125b generates a driving force for driving the compressor 125a using the energy of the exhaust gas.

Note that the exhaust passage 121 is branched to an EGR pipe 126 on the downstream side of the three-way catalyst 123. The EGR pipe 126 is a pipe for recirculating (recirculating) the exhaust gas EGR gas to the intake side. The EGR pipe 126 includes an EGR cooler 127 that cools the EGR, an EGR valve 128 that adjusts the amount of EGR gas, and a pressure sensor 133 that measures the pressure before and after the EGR valve 128. Further, a three-way catalyst 129 different from the three-way catalyst 123 is provided further downstream of the exhaust passage 121.

The intake pipe 110 communicates with the intake passage 130 on the compressor 125a side. The intake passage 130 is provided with a mass flow meter 131 for measuring the air flow rate and a pressure adjusting valve 132 for adjusting the intake pressure. The aforementioned EGR pipe 126 is connected to the intake passage 130. Further, the intake pipe 110 is provided with an oxygen concentration sensor 134 for detecting the oxygen concentration of the mixed gas on the intake side (the gas obtained by mixing the intake air supplied from the intake passage 130 and the EGR gas).

ECU 200 calculates a required torque based on detection signals from accelerator opening sensor 300 and various sensor signals. The ECU 200 determines the opening degree of the pressure adjustment valve 132, the opening degree of the throttle valve 113, the injection pulse period of the fuel injection valve 107, the ignition timing of the ignition plug 105, based on the operating state of the internal combustion engine 100 obtained from the outputs of various sensors. The main operating amounts of the internal combustion engine 100 such as the opening / closing timing of the intake valve 102 and the exhaust valve 103 and the opening degree of the EGR valve 128 are calculated.

The mixed gas flows into the combustion chamber R1 through the intercooler 112, the intake pipe 110, the surge tank 114, and the tumble valve 115 and the intake valve 102. As for this mixed gas, fuel is injected from the fuel injection valve 107 to form an air-fuel mixture in the combustion chamber R1. The air-fuel mixture is ignited and burned by a spark generated from the spark plug 105 at a predetermined ignition timing. The piston 101 is pushed down by the combustion pressure generated by the combustion of the mixer, and becomes a driving force of the internal combustion engine 100.
The exhaust gas after combustion is sent to the three-way catalyst 123 through the exhaust valve 103, the exhaust pipe 111, and the turbine 125b. After the NOx, CO, and HC components are purified in the three-way catalyst 123, the exhaust gas passes through the exhaust passage 121. It is purified again by the three-way catalyst 129 and discharged outside.

Further, a part of the exhaust gas is introduced into the intake passage 130 as EGR gas through the EGR pipe 126, the EGR cooler 127, and the EGR valve 128, and the intake air and the EGR gas are merged in this introduction region. The mixed gas composed of intake air and EGR gas passes through the intake pipe 110 and the like and reaches the combustion chamber R1.

FIG. 2 is a functional block diagram showing the configuration of the ECU 200 according to the first embodiment.
The ECU 200 generally includes an input circuit 201, a CPU 202, a RAM 203, a ROM 204, an input / output port 205, a target supply energy setting unit 206, a current waveform generation unit 207, various drive circuits 208 to 213, and a power control unit 214.

The input circuit 201 is an interface circuit that receives detection signals from various sensors. The CPU 202 is an arithmetic control circuit that controls the entire ECU 200. A RAM 203 is a storage unit for temporarily storing various types of input / output data. The ROM 204 stores a control program describing the contents of arithmetic processing. The input / output port 205 causes the detection signal input from the input circuit 201 to be input to the CPU 202 via the RAM 203 (after being temporarily stored), and the signals transferred from the CPU 202, RAM 203, and ROM 204 to be supplied to various drive circuits 208 to 213. It has the function to output toward Of the detection signals sent to the input circuit 201, the detection signal inputted as an analog signal is inputted after being converted into a digital signal by an A / D converter (not shown) provided in the input circuit 201.

The target supply energy setting unit 206 sets a target supply energy E _tar as an amount of energy to be supplied to the spark plug 105 in accordance with a given operating condition of the internal combustion engine and a physical quantity related to ignition of the spark plug 105. Have The current waveform generation unit 207 has a function of generating current waveform data related to the waveform of the pulsed current supplied to the spark plug 105 according to the set target supply energy E _tar .

For example, the drive circuits 208 to 213 include a pressure adjustment valve drive circuit 208, a throttle valve drive circuit 209, a variable valve mechanism (VTC) drive circuit 210, an injection valve drive circuit 211, an ignition signal output circuit 212, and an EGR valve drive circuit. 213. The pressure adjustment valve drive circuit 208 is an actuator that drives the pressure adjustment valve 132. The throttle valve drive circuit 209 is an actuator that drives the throttle valve 113. The VTC drive circuit 210 is an actuator (valve drive circuit) that drives the intake valve 102 and the exhaust valve 103. The injection valve drive circuit 211 is an actuator that drives the fuel injection valve 107. The ignition signal output circuit 212 outputs an ignition signal for igniting the ignition plug 105. The EGR valve drive circuit 213 is an actuator (valve drive circuit) that drives the EGR valve 128. The power control unit 213 is a control circuit that performs current control and voltage control for supplying power to the ignition plug 105 according to the current waveform data generated by the current waveform generation unit 207.

<Current waveform generation unit 207>
FIG. 3 is a block diagram illustrating an example of a more detailed configuration of the current waveform generation unit 207. As an example, the current waveform generation unit 207 includes a sustain current setting unit 2071, an initial current setting unit 2072, a heating duration calculation unit 2073, a current change rate setting unit 2074, and a correction unit 2075. As a result, the current waveform generator 207 generates current waveform data for generating a current waveform having the initial current i _ini , the current change rate R _cc , and the sustain current i _tar as shown in the lower right of FIG. To do. The initial current i _ini is a current at the rising edge of the current pulse waveform. In addition, the sustain current i _tar is a current that is maintained at least in the subsequent stage of the current pulse waveform and becomes a target value for current increase, and is a current that is larger than the initial current i _ini . The current change rate R _cc represents the degree of change (slope) of the current per unit time when the current value increases from the initial current i _ini to the sustain current i _tar . Current waveform data is generated by sequentially determining the initial current i _ini , the sustain current i _tar and the current change rate R _cc .

The sustain current setting unit 2071 sets the above-described sustain current i _tar according to the target supply energy E _tar set by the target supply energy setting unit 206.
As described above, the target supply energy setting unit 206 is a target supply energy as an amount of energy to be supplied to the spark plug 105 in accordance with the operating condition given to the internal combustion engine 100 and a physical quantity related to ignition of the spark plug 105. E _tar has a function of setting. Here, pressure information relating to the pressure of the air-fuel mixture passing through the spark plug 105, temperature information of the air-fuel mixture, composition information of the air-fuel mixture, and flow rate information of the air-fuel mixture are input as physical quantities related to ignition of the spark plug 105. . Other physical quantities may be included, and combinations thereof are arbitrary.

The initial current setting unit 2072 sets an initial current i _ini that is an initial value of a current pulse to be supplied to the spark plug 105 in accordance with an operation condition given to the internal combustion engine 100 and a physical quantity related to ignition of the spark plug 105. It has a function.

The heating duration calculation unit 2073 starts from the rising edge of the current pulse waveform according to the operating condition given to the internal combustion engine 100, the physical quantity related to ignition of the ignition plug 105, and the maintenance current i _tar set by the maintenance current setting unit 2071. , And has a function of calculating the heating duration Δt _R which is the time until the sustain current i _tar is reached.

The current change rate setting unit 2074 includes the sustain current i _tar set by the sustain current setting unit 2071, the initial current i _ini set by the initial current setting unit 2072, and the heating duration calculated by the heating duration calculation unit 2073. Based on Δt _R , a current change rate R _cc = di / dt is set.

The correction unit 2075 is an achievable energy E _o that is energy that is expected to be achieved by the sustain current i _tar set by the sustain current setting unit 2071, the heating duration Δt _R calculated by the heating duration calculation unit 2073, and the like. And the achievable energy E _o is compared with the target supply energy E _tar described above. Then, the correction unit 2075 corrects physical quantities such as the sustain current i _tar and the current change rate R _cc according to the comparison result.

The internal combustion engine control apparatus of the present embodiment ensures the length of the discharge path of the spark plug 105 by setting an appropriate current change rate _Rcc when setting the current to be supplied to the spark plug 105, Enough supply energy between the gaps can be ensured, whereby the mixture can be favorably ignited to improve the ignition performance and fuel efficiency.

Referring to FIGS. 4 and 5, will be explained the significance of setting the optimum current change rate R _cc. FIG. 4 is a graph showing examples of current pulse waveforms having different current change rates R _cc and changes in various physical quantities obtained thereby, and FIG. 5 shows current pulses (1) having different current change rates R _cc. 3 is a graph showing differences in characteristics of (3) to (3)
The top graph in FIG. 4 shows waveforms (1) to (3) of current pulses flowing through the spark plug 105. (1) is a current pulse waveform of the first comparative example, which is a waveform with a very large current change rate _Rcc . (3) is a current pulse waveform of the second comparative example, in which the current change rate R _cc is small and the waveform gradually reaches the sustain current i _tar . (2) is an example of a current pulse waveform employed in the first embodiment.

As shown in FIG. 6, the length of the discharge path between both electrodes of the spark plug 105 varies depending on the voltage and current between both electrodes, and may vary depending on the flow rate of the air-fuel mixture.
As shown in the second graph of FIG. 4, it can be seen that the waveform of (2) can be the largest in the extension of the discharge path of the spark plug 105. By increasing the elongation of the discharge path, the ignition performance can be maintained even when the pressure in the combustion chamber is high, for example. In the waveform (3), the increase in current cannot catch up with the extension of the discharge path in the first discharge, and re-discharge occurs after the extension of the small discharge path. As a result, the elongation of the discharge path becomes about half of the waveforms of (1) and (2), which is not preferable.

On the other hand, as shown in the third graph of FIG. 4, the gap voltage of the spark plug 105 has almost no difference between the waveform (1) and the waveform (2). Further, as shown in the bottom graph of FIG. 4, regarding the generated energy between the gaps of the spark plug 105, the waveform of (2) has a smaller current change rate than the waveform of (1), It is substantially equivalent to the waveform of (1). As shown in FIG. 5, also in the comparison in the first discharge, the waveform of (2) is larger in the extension of the discharge path than the waveform of (1), and the generated energy between the gaps is also the same as that of (1) Almost inferior. In this way, by generating a current pulse waveform having a current change rate R _cc of an appropriate magnitude, it is possible to increase the extension of the discharge path while ensuring the energy generated between the gaps, and thereby to the air-fuel mixture. The ignition performance and the fuel consumption performance can be improved by performing the ignition of the fuel.

<Operation of Target Supply Energy Setting Unit 206>
An example of a method (operation) for setting the target supply energy E _tar in the target supply energy setting unit 206 will be described.
The target supply energy E _tar can be defined by the following theoretical formula that defines the energy required to realize self-ignition to the air-fuel mixture and flame kernel growth.

Where ρ is the density of the air-fuel mixture, c _p is the specific heat, T _tar is the target temperature, T _adv is the ignition timing temperature, L is the cylinder diameter (electrode diameter) of the discharge path, d is the distance between the electrodes, h is a constant, T _“plug” indicates plug temperature, and “E _FL” indicates flame growth energy.

Another example of a method (operation) for setting the target supply energy E _tar in the target supply energy setting unit 206 will be described with reference to FIG. For example, the target supply energy E _tar can be formed according to a target supply energy map as shown in FIG. A plurality of maps are provided for each different air-fuel ratio or EGR rate, and each map has data of the target supply energy E _tar defined for each combination of the engine speed and the indicated mean effective pressure (IMEP). is doing. According to this map, the target supply energy T _tar can be uniquely determined by determining the air-fuel ratio or the EGR rate and then determining the rotational speed and IMEP.

<Operation of Sustain Current Setting Unit 2071>
Next, an example of a method (operation) for setting the sustain current i _tar in the sustain setting unit 2071 will be described.
As an example, the voltage between the electrodes of the spark plug 105 is V _g , the distance between the electrodes is d, the flow rate of the air-fuel mixture between the electrodes is u, and the cylinder pressure of the internal combustion engine 100 is p, _co , α, and β are constants. In this case, the target supply energy E _tar and the maintenance current i _tar have a relationship represented by the following formula [Equation 2]. When the target supply energy E _tar is determined, the maintenance current i _tar can be determined according to this mathematical formula.

Further, the extension amount of the discharge path can be predicted according to the inter-electrode voltage V _g , the inter-electrode distance d, the flow rate u of the air-fuel mixture between the electrodes, the pressure p of the cylinder of the internal combustion engine 100, and the like. It is also possible to determine the sustain current i _tar based on.

As can be seen from the equation [Equation 2], when the target supply energy E _tar is constant, the smaller the cylinder pressure p, the smaller the sustain current i _tar can be set. Further, the smaller the flow velocity u of the air-fuel mixture, the smaller the sustain current i _tar can be set. The target supply energy setting unit 206 can also input the engine speed as an operating condition of the internal combustion engine. In this case, the sustain current setting unit 2071 can set the sustain current i _tar to a smaller value as the engine speed is smaller.
Further, the opening degree of the tumble control valve 115 can be input to the target supply energy setting unit 206 as the operating condition of the internal combustion engine. In this case, the sustain current setting unit 2071 can set the sustain current i _tar to a smaller value as the opening degree of the tumble control valve 115 is larger. Furthermore, the sustaining current setting unit 2071 can set the sustaining current i _tar to a smaller value as the flow velocity u _sp is smaller.

<Operation of Initial Current Setting Unit 2072>
Next, a method for setting the initial current i _{ini in} the initial current setting unit 2072 will be described with reference to FIGS. FIG. 8 shows the relationship between the initial current i _ini and the amount of expansion of the discharge path of the spark plug 105 when the flow rate of the air-fuel mixture around the spark plug 105 is a predetermined value.

In the example of FIG. 8, in the initial current i _ini small area, but also increased the elongation amount of the discharge path in accordance with an initial current i _ini increases, it becomes more than a certain value initial current i _ini, elongation amount of the discharge path Is saturated. Therefore, in the example of FIG. 8, the initial current i _ini can be determined in consideration of other factors within a range where saturation of the extension amount of the discharge path is not observed. For example, as shown in FIG. 9, it is also possible to determine the initial current i _ini in consideration of the waveform of the secondary current and secondary voltage of the secondary coil (not shown) of the ignition coil 106. Further, the initial current i _ini can be determined in consideration of the discharge path followability C. The discharge path follow-up property C is a numerical value indicating the degree (ease of ease) that the length of the discharge path varies following the change in the pressure of the air-fuel mixture. As shown in FIG. 10, the discharge path followability C can be expressed as a function of the cylinder temperature T, the pressure p, and the like by, for example, the following expression.

_{Here, C ref} is a _constant, the _{u sp} velocity of the mixture around the spark plug _{105 [m / s], T} o is the reference temperature, Po is the reference pressure.

When the discharge path followability C is large, the initial current i _ini can be set large, and when the discharge path followability C is small, the initial current i _ini can also be set small. As shown in FIG. 10, the discharge path follow-up property C increases as the cylinder temperature T increases, and increases as the pressure p increases. For this reason, the initial current setting unit 2072 can set the initial current i _ini to a smaller value as the pressure p is smaller. The same applies to the engine speed, and the initial current setting unit 2072 can set the initial current i _ini to a smaller value as the engine speed is lower. The same applies to the opening degree of the tumble control valve 115, and the initial current setting unit 2072 can set the initial current i _ini to a smaller value as the opening degree of the tumble control valve 115 is larger. Furthermore, the initial current setting unit 2072 can set the current change rate _Rcc to a smaller value as the flow velocity _usp is smaller.
Further, as is clear from the above [Equation 3], the initial current setting unit 2072 can set the initial current i _ini to a smaller value as the flow velocity around the spark plug 105 is smaller.

<Operation of Heating Duration Calculation Unit 2073>
Next, a method for calculating the heating duration Δt _R in the heating duration calculation unit 2073 will be described with reference to FIG. As described above, the heating duration calculation unit 2073 uses the maintenance current i _tar set by the maintenance current setting unit 2071 as a factor in addition to the operating conditions given to the internal combustion engine 100 and the physical quantities related to ignition of the spark plug 105. The heating duration Δt _R is calculated. Specifically, as shown in FIG. 11, the flow velocity u around the spark plug 105 specified from the discharge path elongation L specified from the sustain current i _tar , the engine speed and the opening of the tumble control valve 115. _The heating duration Δt _R is specified by the following formula based on the discharge path follow-up property C specified from the information on _{sp 1} and temperature and pressure.

<Operation of Current Change Rate Setting Unit 2074>
A method (operation) for setting the current change rate R _{cc in} the current change rate setting unit 2074 will be described with reference to FIG.
As shown in FIG. 12, the current change rate R _cc is expressed by the following equation based on the heating duration Δt _R obtained by the heating duration calculation unit 2073, the sustain current i _tar , and the initial current i _ini. Can be determined based on.

Since the current change rate R _cc has the above relationship with the sustain current i _tar , the current change rate setting unit 2074 can set the current change rate R _cc to a larger value as the pressure p increases. Further, the current change rate setting unit 2074 can set the current change rate _Rcc to a larger value as the cylinder temperature T is higher. Moreover, the current change rate setting unit 2074 can set the current change rate _Rcc to a larger value as the engine speed increases. In addition, the current change rate setting unit 2074 can set the current change rate R _cc to a smaller value as the opening degree of the tumble control valve 115 is larger. Furthermore, the current change rate setting unit 2074 can set the current change rate R _cc to a smaller value as the flow velocity u _sp increases.

The current change rate setting unit 2074 calculates, in a case of setting the current change rate R _cc, prior to the time when the elongation amount of the discharge path of the spark plug 105 is maximized, the target electric energy calculating unit (206) It is preferable to set the current change rate Rcc so that a current and voltage corresponding to the target supply energy amount E _tar are supplied to the spark plug 105. That is, it is preferable to control the current so that the target supply energy amount Etar flows through the spark plug 105 before the extension amount of the discharge path of the spark plug 105 reaches the maximum. By setting the current change rate Rcc in this manner, the elongation of the discharge path can be stably increased, and the occurrence of misfire can be reliably prevented. The power control unit 214 supplies current according to the set current waveform data.

<Operation of Correction Unit 2075>
When the target supply energy E _tar , the maintenance current i _tar , the initial current i _ini , the heating duration Δt _R , and the current change rate R _cc are obtained as described above, the correction unit 2075 corrects the obtained values. Done.

FIG. 13 is a flowchart illustrating an example of a correction procedure in the correction unit 2075.
First, in step S11, an achievable energy E _o that is an achievable energy by various set numerical values is calculated. As an example, the achievable energy E _o may be calculated by E _o = V _g × i _tar × Δt _R.

Subsequently, in steps S12 and S13, the achievable energy E _o is compared with the target supply energy E _tar described above, and the magnitude relationship between the two is determined. If Eo = E _tar (or E _o ≈E _tar ), no correction is performed (step S14), and the correction unit 2075 outputs the obtained numerical value as it is as current waveform data.

On the other hand, if E _o > E _tar (Yes in S12), the correction unit 2075 corrects the sustain current i _tar and sets the correction value i _tar ′ as a new sustain current (step S15). The correction value i _tar ′ is set to, for example, i _tar ′ = max (I _tar × E _tar / E _o , i _{lim, b} ) (where i _{lim, b} is the lower limit value of the sustain current i _tar ). . Thereby, the sustain current i _tar is corrected to a lower value, and the achievable energy E _o is also adjusted to a value substantially equal to the target supply energy E _tar .

When E _o <E _tar (Yes in S13), the correction unit 2075 corrects the sustain current i _tar and sets the correction value i _tar ′ as a new sustain current (step S16). The correction value i _tar ′ is set to, for example, i _tar ′ = min (I _tar × E _tar / E _o , i _{lim, u} ) (where i _{lim, u} is the upper limit value of the sustain current i _tar ). . Thereby, the sustain current i _tar is corrected to a larger value, and the achievable energy E _o is also adjusted to a value substantially equal to the target supply energy E _tar .

When the sustain current itar is corrected in step s15 or S16 (i _tar → i _tar '), the current change rate R _cc is corrected in step S17. Here, the current change rate R _cc ′ = (i _tar ′ −i _ini ) / (a × Δt _R ) is expressed as a new current change rate R using the newly obtained correction value i _tar ′ of the sustain current itar. _cc .
The example of the correction operation in the correction unit 2075 has been described above. In the above example, the case where the correction is performed on the sustain current i _tar and the current change rate R _cc has been described. Instead, the initial current i _ini , the sustain current i _tar and the current change rate R _cc are corrected. It is also possible to adopt. It is also possible to perform correction only for the current change rate _Rcc .

14 to 16, an example of current pulse waveform data and discharge current according to the first embodiment will be described. 14 to 16, the primary coil of the ignition coil 106 is composed of a first coil and a second coil connected in series. The discharge current is supplied to the first coil and the overlap current is supplied to the second coil. The operation when applied is shown.

FIG. 14 shows a waveform when the engine speed gradually increases, FIG. 15 shows a waveform when the load gradually increases, and FIG. 16 shows a waveform when the air-fuel ratio changes. Is shown.
FIG. 14 shows how the heating duration Δt _R gradually decreases as the engine speed increases. FIG. 15 shows how the initial current i _ini gradually increases as the load gradually increases. FIG. 16 shows how the sustain current i _tar increases as the air-fuel ratio increases.

<Effect of the first embodiment>
As described above, according to the internal combustion engine control apparatus of the first embodiment, the target supply energy calculation unit 206 calculates the amount of energy required for ignition in the combustion chamber of the internal combustion engine based on a predetermined factor. In the current waveform generation unit 207, data relating to the waveform of the current supplied to the spark plug is generated according to this energy amount. The power control unit 213 controls power according to the current waveform data. According to this, the waveform of the current supplied to the spark plug is optimized, and the air-fuel mixture can be favorably ignited to improve the ignition performance and fuel consumption performance.

[Second Embodiment]
Next, an internal combustion engine control apparatus according to a second embodiment will be described with reference to FIG. Since the basic configuration of the second embodiment is the same as that of the first embodiment (FIGS. 1 to 3), duplicate description is omitted. However, in the second embodiment, the method of setting the target supply energy E _tar in the target supply energy setting unit 206 is different from that of the first embodiment.

In the second embodiment, a reference supply energy map is provided to obtain the target supply energy E _tar . The reference supply energy map is map data for _obtaining a reference supply energy E _base that serves as a reference for _obtaining the target supply energy E _tar . The reference supply energy map is a set of reference supply energy E _base values defined for each combination of engine speed and indicated mean effective pressure (IMEP). One set of engine speed value and indicated mean effective pressure The value of one reference supply energy E _base is determined. Thereafter, the target supply energy E _tar can be calculated, for example, as a value obtained by multiplying the value of the reference supply energy E _{base by} the value of the function F of the air-fuel ratio A / F, the EGR rate Y _EGR , and the ignition timing temperature TADV. it can.

[Third embodiment]
Next, an internal combustion engine control apparatus according to a third embodiment will be described with reference to FIG. Since the basic configuration of the third embodiment is the same as that of the first embodiment (FIGS. 1 to 3), duplicate description is omitted. However, in the third embodiment, the method of setting the sustain current i _tar in the sustain current setting unit 2071 is different from that of the first embodiment.
In the third embodiment, a standard sustain current map is provided to obtain the sustain current I _tar . The standard maintenance current map is map data for _obtaining a standard maintenance current i _base that is a reference for _obtaining the standard current i _tar . The standard maintenance current map is different for each different air-fuel ratio or EGR rate, for example. Each map is a standard maintenance current defined for each combination of engine speed and indicated mean effective pressure (IMEP). It is a set of i _base values. When one set of engine speed value and indicated mean effective pressure value are determined, one standard maintenance current _iase value is determined. Thereafter, the standard current i _tar can be calculated as a value obtained by multiplying the value of the standard sustain current i _base by a predetermined variable, for example.

[Others]
In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 100 ... Internal combustion engine, 101 ... Piston, 102 ... Intake valve, 103 ... Exhaust valve, 105 ... Ignition plug, 106 ... Ignition coil, 107 ... Fuel injection valve, 110 ... Intake pipe, 111 ... Exhaust pipe, 112 ... Intercooler, 113 ... Throttle valve, 114 ... Surge tank, 115 ... Tumble control valve, 121 ... Exhaust passage, 123, 129 ... Three-way catalyst, 124 ... Air-fuel ratio sensor, 125a ... Compressor, 125b ... Turbine, 126 ... EGR piping, 127 ... EGR cooler, 128 ... EGR valve, 130 ... intake passage, 131 ... mass flow meter, 132 ... pressure regulating valve, 133 ... pressure sensor, 134 ... oxygen concentration sensor, 201 ... input circuit, 205 ... input / output port, 206 ... target Supply energy -Setting unit, 207 ... Current waveform generation unit, 208 ... Pressure adjustment valve drive circuit, 209 ... Throttle valve drive circuit, 210 ... Variable valve mechanism (VTC) drive circuit, 211 ... Injection valve drive circuit, 212 ... Ignition signal output circuit 213, EGR valve drive circuit, 214, power control unit, 300, accelerator opening sensor.

Claims

In an internal combustion engine controller for controlling an internal combustion engine provided with an ignition coil and an ignition plug,
A target supply energy calculation unit that calculates an amount of energy required for ignition of an air-fuel mixture supplied to a combustion chamber of the internal combustion engine based on an operating condition of the internal combustion engine or a physical quantity related to ignition of the spark plug;
A current waveform generator for generating current waveform data relating to a waveform of a current supplied to the spark plug according to the energy amount;
An internal combustion engine control device comprising: an electric power control unit that controls electric power supplied to the spark plug according to the current waveform data.
The current waveform generation unit further includes a current change rate setting unit that sets a current change rate indicating a degree of change per unit time of the current until the current reaches a sustain current. Internal combustion engine control device.
3. The internal combustion engine control device according to claim 1, wherein the current waveform generation unit further includes an initial current setting unit that sets an initial current that is an initial value of the current.
The internal combustion engine control device according to any one of claims 1 to 3, wherein the current waveform generation unit further includes a maintenance current setting unit that sets a maintenance current that is a target value of the current.
The internal combustion engine control device according to claim 4, wherein the current waveform generation unit further includes a heating duration calculation unit that calculates a heating duration during which heating by the current is continued.
The correction unit according to any one of claims 1 to 5, further comprising a correction unit that corrects the current waveform data according to whether or not necessary energy can be obtained from the current waveform data set by the current waveform generation unit. Internal combustion engine control device.
The power control unit controls the current so that the amount of energy calculated by the target supply energy calculation unit flows through the spark plug before the extension amount of the discharge path of the spark plug reaches a maximum. The internal combustion engine control apparatus described.
The physical quantity is a pressure of a cylinder of the internal combustion engine,
The internal combustion engine control device according to claim 2, wherein the current change rate setting unit sets the current change rate to a larger value as the pressure of the cylinder increases.
The physical quantity is a temperature of a cylinder of the internal combustion engine,
The internal combustion engine control device according to claim 2, wherein the current change rate setting unit sets the current change rate to a larger value as the temperature of the cylinder is higher.
The operating condition of the internal combustion engine is the engine speed,
The internal combustion engine control device according to claim 2, wherein the current change rate setting unit sets the current change rate to a larger value as the engine speed increases.
The operating condition of the internal combustion engine is the opening of the tumble control valve,
The internal combustion engine control device according to claim 2, wherein the current change rate setting unit sets the current change rate to a smaller value as the opening degree of the tumble control valve is larger.
The operating condition of the internal combustion engine is the flow velocity around the spark plug,
The internal combustion engine control device according to claim 2, wherein the current change rate setting unit sets the current change rate to a smaller value as the flow velocity increases.
The physical quantity is cylinder pressure,
The internal combustion engine control device according to claim 3, wherein the initial current setting unit sets the initial current to a smaller value as the pressure in the cylinder is smaller.
The operating condition of the internal combustion engine is the engine speed,
The internal combustion engine control device according to claim 3, wherein the initial current setting unit sets the initial current to a smaller value as the engine speed is smaller.
The operating condition of the internal combustion engine is the opening of the tumble control valve,
The internal combustion engine control device according to claim 3, wherein the initial current setting unit sets the initial current to a smaller value as the opening of the tumble control valve is larger.
The operating condition of the internal combustion engine is the flow velocity around the spark plug,
The internal combustion engine control device according to claim 3, wherein the initial current setting unit sets the initial current to a smaller value as the flow velocity around the spark plug is smaller.
The physical quantity is a pressure of a cylinder of the internal combustion engine,
The internal combustion engine control device according to claim 4, wherein the maintenance current setting unit sets the maintenance current to a smaller value as the pressure of the cylinder is smaller.
The operating condition of the internal combustion engine is the engine speed,
The internal combustion engine control device according to claim 4, wherein the maintenance current setting unit sets the maintenance current to a smaller value as the engine speed is smaller.
The operating condition of the internal combustion engine is the opening of the tumble control valve,
The internal combustion engine control device according to claim 4, wherein the maintenance current setting unit sets the maintenance current to a smaller value as the opening degree of the tumble control valve is larger.
The operating condition of the internal combustion engine is the flow velocity around the spark plug,
The internal combustion engine control device according to claim 4, wherein the maintenance current setting unit sets the maintenance current to a smaller value as the flow velocity around the spark plug is smaller.
In an internal combustion engine controller for controlling an internal combustion engine provided with an ignition coil and an ignition plug,
An energy calculating unit that calculates an amount of energy required for ignition of an air-fuel mixture supplied to a combustion chamber of the internal combustion engine based on an operating condition of the internal combustion engine or a physical quantity related to ignition of the spark plug;
According to the calculation result in the energy calculation unit, a current waveform generation unit that generates current waveform data related to the waveform of the current supplied to the spark plug;
A power control unit for controlling the power supplied to the spark plug according to the current waveform data,
The current waveform generator includes an initial current, a sustain current larger than the initial current, and a current change rate indicating a degree of change per unit time of the current between the initial current and the sustain current. An internal combustion engine control device characterized by setting.
The internal combustion engine control device according to claim 21, further comprising a correction unit that corrects the current waveform data according to whether or not necessary energy can be obtained from the current waveform data set by the current waveform generation unit.
The said electric power control part controls an electric current so that the energy amount computed by the said energy calculation part may be sent through the said ignition plug before the amount of expansion of the discharge path of the said ignition plug becomes the maximum. Internal combustion engine control device.