JP2008232035A - Operation controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation controller of an internal combustion engine capable of more adequately implementing a lean operation even if alcohol concentration varies in a composite fuel of gasoline and alcohol. <P>SOLUTION: The operation controller is equipped with a fuel injection valve 15 which implements injection of the composite fuel of gasoline and alcohol, an ignition means 16 which ignites the composite fuel within a cylinder, an alcohol concentration detection means which detects the alcohol concentration α of the composite fuel, an operational region determining means A2 which sets a condition of whether or not the present operational region is one where the lean operation is possible based on the alcohol concentration, and a control means A0 which controls at least one of injection timing t1m of the injection valve or ignition timing ti1 of the ignition means so that when the condition has been judged to be in a region where the lean operation is possible, the higher the alcohol concentration in the composite fuel, the longer the period Δc1 from injection completion timing t1e of the fuel injection valve to ignition timing ti1 of the ignition means 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an operation control device for an internal combustion engine, and more particularly, to an operation control device for an internal combustion engine in which a mixed fuel of gasoline and alcohol is directly injected into a cylinder to perform a lean operation.

  Development of the so-called FFV (Flexible Fuel Vehicle), which is one of the vehicles using gasoline alternative fuel, which can maintain the driving characteristics while maintaining whatever the mixing ratio of gasoline and alcohol. Is progressing. In such a mixed fuel vehicle using a mixed fuel of gasoline and alcohol, it is necessary to make an increase correction of the injection amount because the calorific value of alcohol is lower than that of gasoline. Furthermore, when the alcohol concentration is high and the alcohol concentration is high, for example, as shown in FIG. 9 as an example, it is necessary to improve the starting characteristics due to the lowering of the vaporization characteristics.

By the way, a direct injection engine in which fuel is directly injected into a cylinder is known, and development is progressing to use a mixed fuel of gasoline and alcohol for the direct injection engine.
For example, in the control device for a direct injection engine using a mixed fuel of gasoline and alcohol disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2005-220820), a lean operation is performed for each predetermined concentration range corresponding to the alcohol concentration. When the stratified region determination map showing the operation region that can be operated and the parameter map in which the injection control amount for lean operation is set in advance are determined to be the lean operation region based on the alcohol concentration, it is set in the parameter map. The lean operation is performed by the injection control amount.

Japanese Patent Laid-Open No. 2005-220820

However, when using a fuel mixture of gasoline and alcohol, the vaporization characteristics of the fuel spray are likely to fluctuate depending on the engine ambient temperature, for example, the water temperature and intake air temperature. Along with this, the combustion performance is likely to fluctuate relatively greatly, and this is considered to be a factor causing deterioration in combustion.
However, as in Patent Document 1, an operation region in which a lean operation can be performed for each concentration range is simply set corresponding to the alcohol concentration, and further, an ignition timing, an injection timing, an injection period, etc. are set corresponding to the alcohol concentration. Lean operation control cannot be performed without causing deterioration of combustion only by performing a control process in which the control parameter amount is set. That is, in the technique of Patent Document 1, since the vaporization characteristics of the fuel spray are not sufficiently taken into account, it is not possible to stably perform lean operation control without causing deterioration of combustion in response to changes in alcohol concentration.

Further, when the mixed fuel has a high alcohol concentration, it is likely to increase the fuel injection amount. In such a case, if a large fuel injection valve with a high injection amount is used in order to cope with this, a problem is likely to occur in the mountability, and improvement is also desired in this respect.
The present invention has been made paying attention to the above-described problems, and provides an operation control device for an internal combustion engine that can perform a lean operation more appropriately even if the alcohol concentration of a mixed fuel of gasoline and alcohol changes. It is intended to provide.

  In order to achieve the above-mentioned object, the invention of claim 1 is directed to a fuel injection valve that injects a mixed fuel of gasoline and alcohol into a cylinder of an internal combustion engine, and the mixture injected from the fuel injection valve in the cylinder. An operating range in which the internal combustion engine can perform a lean operation based on ignition means for igniting fuel, alcohol concentration detection means for detecting alcohol concentration in the mixed fuel, and alcohol concentration detected by the alcohol concentration detection means The fuel injection valve injection end timing is higher as the alcohol concentration in the mixed fuel is higher when the operation region determination means determines whether or not the operation region determination means determines that the operation region can be operated lean. Control means for controlling at least one of the injection timing of the fuel injection valve or the ignition timing of the ignition means so that the period from the ignition timing to the ignition timing of the ignition means becomes longer, Characterized in that it comprises.

  The invention of claim 2 is a fuel injection valve for injecting a mixed fuel of gasoline and alcohol into a cylinder of an internal combustion engine, and an ignition means for igniting the mixed fuel injected from the fuel injection valve in the cylinder, An alcohol concentration detecting means for detecting an alcohol concentration in the mixed fuel, and an operating range for determining whether or not the internal combustion engine is in an operating range where the lean operation is possible based on the alcohol concentration detected by the alcohol concentration detecting means. Control means for controlling the ignition timing of the ignition means to be delayed as the alcohol concentration in the mixed fuel is higher when the determination means and the operation area determination means determine that the lean operation is possible. It is characterized by providing.

  According to a third aspect of the present invention, in the internal combustion engine operation control apparatus according to the first or second aspect, the number of fuel injections of the fuel injection valve can be set according to the alcohol concentration, and the alcohol concentration is The higher the operating range in which the lean operation can be performed by injecting the fuel injection valve a plurality of times, the wider is set.

  According to a fourth aspect of the present invention, in the operation control device for an internal combustion engine according to the first, second, or third aspect, the operating range determination means includes a low alcohol concentration lower than a predetermined alcohol concentration, and a low alcohol concentration The determination is made according to the time when the alcohol concentration is higher than the high alcohol concentration, and the operation range in which it is determined that the lean operation is possible is set wider at the time of the low alcohol concentration than at the time of the high alcohol concentration. It is characterized by.

  According to a fifth aspect of the present invention, in the operation control device for an internal combustion engine according to any one of the first to fourth aspects, the operation range determination means further uses the intake air temperature and the water temperature of the internal combustion engine to perform the lean operation. It is characterized by determining whether it is a possible driving | operation area | region.

  According to the first aspect of the present invention, even if there is a change in the alcohol concentration of the mixed fuel, the mixed fuel can be injected into the cylinder and appropriately lean burned. Moreover, as the alcohol concentration of the mixed fuel is higher, at least one of the injection timing of the fuel injection valve or the ignition timing of the ignition means is controlled so that the elapsed time from the injection end timing to the ignition timing becomes longer. A sufficient atomization period before ignition of the injected fuel can be ensured, ignition can be ensured, and lean operation characteristics can be improved.

  According to the second aspect of the present invention, even if there is a change in the alcohol concentration of the mixed fuel, the mixed fuel can be injected into the cylinder and appropriately lean burned. In addition, the higher the alcohol concentration of the mixed fuel, the slower the ignition timing, so that a sufficient atomization period before ignition of the fuel injected into the cylinder can be secured, ignition can be ensured, and lean operation characteristics can be achieved. Can be improved.

  According to the third aspect of the present invention, the number of injections of the fuel injection valve is variably set to a plurality of times according to the operating range of the internal combustion engine. However, even if the injection amount tends to increase, the fuel can be injected in a plurality of times, which can be dealt with only by using a single fuel injection valve, and there is no need to separately use fuel injection valves having different specifications.

  According to the fourth aspect of the present invention, the operating range in which it is determined that lean operation is possible at a low alcohol concentration is set wider than at high alcohol concentration, and it is determined that the lean operation is possible at a low alcohol concentration. The driving range can be expanded to improve fuel efficiency.

  According to the fifth aspect of the present invention, since the operating range in which the lean operation can be performed is appropriately corrected according to the engine water temperature in addition to the intake air temperature, the fuel mixture of gasoline and alcohol can be reliably ignited, and the lean Driving characteristics can be improved.

  FIG. 1 shows a direct injection engine (hereinafter simply referred to as an engine) 1 that can use a mixed fuel of gasoline and alcohol to which an operation control device for an internal combustion engine is applied. The engine 1 is an in-line four-cylinder engine mounted on a vehicle (not shown), and an engine body includes a cylinder block 5 that slidably supports a piston 4 connected to a crankshaft 2 via a connecting rod 3. A cylinder head 6 and a head cover 7 are sequentially and integrally connected to the upper side of the cylinder block 5, and an oil pan 8 that closes the lower side is integrally connected to the lower side of the cylinder block 5, and these constitute an engine body.

  As shown in FIG. 1, a combustion chamber C is provided inside each of a plurality of cylinders 9 (only one cylinder is shown in FIG. 1) provided in the engine body. Intake air is introduced into each combustion chamber C via an intake port 11, and exhaust gas is discharged via an exhaust port 12. The intake valve 13 that opens and closes the intake port 11 and the exhaust valve 14 that opens and closes the exhaust port 12 are driven by a valve system (not shown) of an intake system and an exhaust system, respectively. The rotational energy generated in the combustion chamber C is transmitted as a rotational force to the crankshaft 2 through the piston 4 and the connecting rod 3. The cylinder head 6 is provided with a fuel injection valve (injector) 15 and a spark plug 16 at a portion facing the combustion chamber C of each cylinder so as not to interfere with the intake valve 13 and the exhaust valve 14.

Air from the air cleaner 17 is introduced into the combustion chamber C of each cylinder through an intake passage IR communicating with the intake port 11, and is subjected to flow control by an electric throttle valve (hereinafter simply referred to as a throttle valve) 18 in the intake passage IR. Inhaled. Exhaust gas from the engine 1 is discharged from an exhaust passage ER communicating with the exhaust port 12. A catalyst (not shown) for exhaust purification is interposed in the exhaust passage ER.
A fuel injection valve (hereinafter referred to as an injector) 15 of each cylinder of the engine 1 is supplied with a mixed fuel of gasoline and alcohol from a fuel supply device 22 described later. Further, the injector 15 includes an exciting coil 151, which is fuel-driven by being driven and controlled by an electronic control unit (hereinafter referred to as a controller) 19 described later.

  The excitation coil 151 of each injector 15 is excited from the controller 19 in the intake stroke and the compression stroke in synchronization with the engine rotation, and injection drive control is performed. Here, the injector 15 is opened by receiving pulses corresponding to injection pulse signals (valve opening signals) T1m, T2f, and T2r, which will be described later, as shown in FIGS. 3 and 4, and a mixed fuel of gasoline and alcohol is supplied. It is injected into the combustion chamber C. The fuel mixture of gasoline and alcohol injected here is diffused as a homogeneous air-fuel mixture in the combustion chamber C in the intake stroke. Further, in the case of the compression stroke, the piston cavity 21 serves as a stratified mixture around the spark plug 16 in a concentrated manner.

Here, the injector 15 is arranged relatively close to the spark plug 16 on the center side of the combustion chamber C (shown schematically in FIG. 1). For this reason, the upper end side portion of the spray from the injector 15 is set so as to pass directly over the spark discharge gap (discharge space) t (see FIG. 1) of the spark plug 16 to ensure ignitability. Yes.
During the intake stroke injection, the injector 15 opens, for example, by receiving a single injection pulse signal (valve opening signal) T1m as shown in FIG. Homogeneous injection can be performed.

  At this time, the injector 15 applies a single main injection drive pulse T1m (injection period), which is a fuel injection valve drive signal from the controller 19, to the excitation coil 151 between the predetermined injection timing t1m and the injection end timing t1e. (See FIG. 3). As a result, it is possible to perform injection driving so as to perform one homogeneous injection of an injection amount (corresponding to a pulse width) Q1m corresponding to the injection period of the drive pulse T1m. The spray from the injector 15 is collected near the ignition plug 16 on the center side of the combustion chamber C as the compression stroke progresses. The upper end portion of the spray is ignited when it passes through a position directly applied to the spark discharge gap (discharge space) t (see FIG. 1) of the spark plug 16 (the time indicated by the star in FIG. 5).

Next, at the time of compression stroke injection, the injector 15 receives two injection pulse signals (valve opening signals) T2f and T2r as shown in FIG. Fuel can be injected in layers.
At this time, the injector 15 applies two main injection drive pulses T2f and T2r (injection period), which are fuel injection valve drive signals from the controller 19, to the excitation coil 151 from the predetermined injection timings t2f and t2r to the injection end timing t2fe. , T2re (see FIG. 4). As a result, it is possible to perform injection driving so as to perform two injections of the injection amount (corresponding to the pulse width) Qm2 (= Q2f + Q2r) corresponding to the injection period of the drive pulses T2f and T2r. As the spray from the injector 15 approaches the compression top dead center, the upper end side portion of the air-fuel mixture sprayed in layers in the cavity 21 passes through the spark discharge gap t of the spark plug 16 (the asterisk in FIG. 5). Ignition is performed at the time of ().

As shown in FIG. 1, a fuel supply device 22 that supplies fuel to a fuel injection valve (hereinafter referred to as an injector) 15 includes a fuel tank 26, and a low-pressure supply passage 28 supplies a mixed fuel of gasoline and alcohol in the fuel tank 26. To the low pressure pump 27 and the high pressure pump 29.
The low pressure pump 27 and the high pressure pump 29 are unitized as a pump unit PU. The pump unit PU includes a pump shaft 33 connected to a drive shaft (not shown) of the engine 1 via a rotation transmission system, and is driven to rotate in synchronization with the rotation of the engine 1 via the pump shaft 33. In the pump unit PU, a vane type feed pump (low pressure pump 27) (not shown) and a plunger (high pressure pump 29) (not shown) for pumping fuel are driven in conjunction with the rotation of the pump shaft 33. The low pressure pump 27 pumps the fuel from the fuel tank 26 to a low pressure chamber (not shown), and then the high pressure pump 29 increases the pressure of the low pressure mixed fuel and supplies it to one end of the delivery pipe 23 via the fuel pressure regulator 34. . The fuel pressure adjuster 34 is controlled by the controller 19 and can adjust the fuel pressure so that the fuel pressure in the delivery pipe 23 becomes a predetermined value.

As shown in FIG. 1, an alcohol concentration sensor 32 is provided in the middle of the low pressure supply passage 28 as alcohol concentration detection means for detecting the alcohol concentration α of the fuel mixture of gasoline and alcohol based on a change in dielectric constant. Yes.
In FIG. 1, reference numeral 30 indicates a return passage for returning surplus fuel from each injector 15 to the fuel tank 26. A pressure limiter (not shown) that functions to suppress an excessive increase in fuel pressure is provided at the other end of the delivery pipe 23, and a low-pressure pipe (not shown) from the pressure limiter returns excess fuel to the fuel tank 26. It is connected.
A spark plug 16 is provided in the center of the wall portion of the cylinder head 6 facing the combustion chamber C.

As shown in FIG. 1, an igniter 24 is connected to the upper end portion of the spark plug 16. The igniter 24 generates an ignition high voltage when receiving an ignition signal from the controller 19, and the ignition high voltage is applied to the ignition plug 16, and the spark discharge generated in the spark discharge gap t of the ignition plug 16 The air-fuel mixture in the combustion chamber C is ignited.
The controller 19 includes an input / output device (not shown), a storage device (ROM, RAM, DRAM, etc.) used for storing control programs and control maps, a central processing unit (CPU), a timer counter (not shown), and the like.

On the input circuit 191 side of the controller 19, an accelerator opening sensor 37 that detects an accelerator opening θa that is a load signal, an airflow sensor 38 that detects an intake air amount Qa, and a reference pulse signal ( A crank position sensor 39 for outputting Cb (used also for a cylinder discrimination signal) and outputting a unit crank angle signal Δθ every 1 to 2 ° is provided.
In addition, on the input circuit 191 side, an intake air temperature sensor 41 for detecting the intake air temperature at in the air cleaner 17, a throttle position sensor 40 for detecting the opening θs of the throttle valve 18, and a water temperature for detecting the cooling water temperature wt of the engine 1. A sensor 42, an air-fuel ratio sensor 43 that outputs a signal corresponding to the rich / lean exhaust air-fuel ratio in the exhaust passage ER, an alcohol concentration sensor 32 that detects the alcohol concentration α, and the like are provided.

As shown in FIG. 2, the controller 19 functioning as an engine operation control device has functions as a control means A0, a target injection amount setting means A1, and an operation range determination means A2.
The control means A0 basically depends on the data from the target injection amount setting means A1 and the operation range determination means A2 and other engine operation information such as the alcohol concentration α, the engine speed Ne, and the accelerator opening θa. The fuel injection valve 2 and the spark plug 16 of each cylinder C are driven and controlled.

Next, the target injection amount setting means A1 first sets the accelerator opening θa, the engine rotation speed Ne, the air-fuel ratio A / F, the water temperature wt, the alcohol concentration α, etc., which are engine operation information, for each cylinder of the engine 1. take in. Based on these data, the basic fuel injection amount INJb at the alcohol concentration α of zero% (gasoline 100%) is calculated. Then, correction values Q _{A / F} and Qwt such as an air-fuel ratio A / F (a different value depending on the stoichiometric and lean injection modes) and a water temperature wt are added to the calculated basic fuel injection amount INJb, and the current alcohol concentration α Multiply by a corresponding correction coefficient Kα to calculate the target injection amount QFS, QFR {= (INJb + QA / F + Qwt) × Kα} in each injection mode (here, each value in stoichiometric or enriched injection mode and lean injection mode) It is carried out. The correction coefficient Kα is appropriately set in consideration of the equivalent ratio of alcohol as a value that increases as the alcohol concentration α described later increases.

  First, the operation region determination means A2 sets the alcohol concentration region (alcohol concentration change region) into a plurality of alcohol concentration regions. Here, in consideration of the alcohol vapor pressure characteristic shown as an example in FIG. 9, the predetermined alcohol concentration used for determination of the operation region where the lean operation is possible is set as the high alcohol concentration determination value αa (for example, alcohol 50%). Set. Accordingly, as shown in FIG. 9, the alcohol concentration range is set to be divided into a low alcohol concentration range e1 (for example, less than 50% alcohol) and a high alcohol concentration range (for example, 50% or more alcohol) e2.

Note that the threshold for determining the operation range in which lean operation is possible is set as 50% alcohol, but the threshold value in the low alcohol concentration region e1 in which lean operation is possible is corrected to a value other than 50%. It is also possible to do.
Next, the operating range determination means A2 outputs a low alcohol concentration signal Se1 in the low alcohol concentration range e1 where the alcohol concentration α obtained by the alcohol concentration sensor 32 is less than 50% set in advance, and the high concentration of 50% or more. In the alcohol concentration range e2, a high alcohol concentration signal Se2 is output.

  In addition, the intake air temperature at and the water temperature wt of the engine 1, which are a plurality of engine atmosphere temperature parameters, are taken for each of the low and high alcohol concentration ranges, and it is determined based on these whether or not the operation range is capable of lean operation. . Here, the operating range in which the lean operation can be performed is appropriately corrected according to the water temperature wt in addition to the intake air temperature at, so that the fuel mixture of gasoline and alcohol can be reliably ignited and the lean operation characteristics can be improved. .

  Specifically, the operation region determination process uses lean operation permission region setting maps MAPL and MAPH for each alcohol concentration region divided into two as shown in FIGS. 6 (a) and 6 (b). It is determined whether or not the vehicle is in a permitted operation range where operation is possible or an operation region in which lean operation is not permitted. That is, when the high alcohol concentration signal Se2 is read, the lean operation permission area setting map MAPH is used at the time of the high alcohol concentration of FIG. When the low alcohol concentration signal Se1 is read, the lean operation permission area setting map MAPL is used at the time of the low alcohol concentration in FIG.

  Here, at the time of the low alcohol concentration of FIG. 6A, the lean operation permission area is set wider than that at the time of the high alcohol concentration of FIG. In other words, when the alcohol concentration is low, the engine atmosphere temperature is set to a relatively low temperature side compared to when the alcohol concentration is high, thereby improving fuel consumption. On the other hand, as shown in FIG. 6 (b), the lean operation permission region is relatively narrowed to the high temperature side of the engine atmosphere temperature in consideration of the lowering of the vaporization property of the spray fuel when the alcohol concentration is high, and the alcohol concentration α is high. Suppresses the decrease in ignitability due to.

Next, the function of the control means A0 will be further described.
Specifically, the control means A0 has functions of a control amount setting unit A01, an injection control unit A02, and an ignition control unit A03.
The control amount setting unit A01 sets a control amount for each parameter that affects the lean operation of the fuel injection valve 15 according to the alcohol concentration α.
First, as a parameter that affects lean operation, the number of injections Ni in the operation region in which the lean operation is possible is set, and the number of injections Ni of the fuel injection valve 15 is set to the engine rotational speed Ne that is the operation region of the engine 1 and the engine load. Is variably set according to the accelerator opening θa.

That is, the injection number setting maps MAPNL and MAPNH as shown in FIGS. 7A and 7B are used.
Here, when the low alcohol concentration signal Se1 is detected, the injection number setting map MAPNL at the time of low alcohol concentration in FIG. 7A is used. Here, it is a case where the high alcohol concentration determination value αa (for example, 50%) is below and the gasoline ratio is large, and a region where the target injection amount QFS is performed by one injection is relatively large.

On the other hand, when the high alcohol concentration signal Se2 is detected, the injection number setting map MAPNH at the time of high alcohol concentration in FIG. 7B is used. Here, the high alcohol concentration determination value αa is exceeded and the alcohol ratio is large, and in order to cope with the relatively increased target fuel injection amount QFR at the time of high alcohol concentration, the higher the alcohol concentration α, the more the multiple injection region. The two-time injection region is set to be wide, and the one-time injection region is set to be relatively small.
Further, the control amount setting unit A01 sets a control amount for each parameter that affects the lean operation of the fuel injection valve 15 according to the alcohol concentration α.

First, the control amount setting unit A01 takes in the low alcohol concentration signal Se1 (low alcohol concentration region e1) and the high alcohol concentration signal Se2 (high alcohol concentration region e2), which are data from the operation region determination means A2.
Furthermore, irrespective of the alcohol concentration α, in the case of stoichiometric or enrichment operation, a control amount for each parameter that affects uniform combustion is set accordingly.

For example, when an input signal of the target injection amount QFS calculated in advance is received, the corresponding injection pulse width Tsm and injection timing tsm are set as shown in the stoichiometric / enriched operation region in FIG. Further, the control amount setting unit A01 sets a steady ignition timing ti1 (a value obtained by correcting a reference value corresponding to the engine speed according to the load) in the stoichiometric and enriched operation region.
The injection control unit A02 performs injection drive control according to the injection data “Tsm, tsm”, and the ignition control unit A03 performs ignition drive control according to the ignition data “ti1”.

Next, in the control amount setting unit A01, when the low alcohol concentration signal Se1 is received from the operation region determination means A2, the control amount in the operation region (compression stroke: double injection) in the lean operation mode in FIG. The control amount in the operation region (intake stroke: single injection) in the lean operation mode is set.
Here, the injection amount (corresponding to the pulse width) Q1m, Q2f, Q2r (which is a parameter that affects the lean operation according to either one or two times selected from the injection number Ni data obtained previously. 1 or 2 injection pulses T1m, T2f, T2r, injection timings t1m, t2f, t2r, and injection end timings t1e, t2fe, t2re are set. Further, the control amount setting unit A01 receives the low alcohol concentration signal Se1 and sets the ignition timing ti1 (a value obtained by correcting the reference value according to the engine speed according to the load) in the operation region in the lean operation mode.

The injection control unit A02 performs injection driving control according to these injection data “T1m, T2f, T2r, t1m, t2f, t2r, t1e, t2fe, t2re”, and the ignition control unit A03 performs ignition driving according to the ignition data “ti1”. Control.
Further, when the high alcohol concentration signal Se2 is received based on the data from the operation region determination means A2, the control amount in the operation region (compression stroke: twice injection) in the lean operation mode in FIG. A control amount is set in the operation region in the mode (intake stroke: one injection).

  Here, injection amounts Q1m ′, Q2f ′, and Q2r (not shown), which are parameters that affect the lean operation according to either one or two selected from the injection number Ni data obtained previously. One or two injection pulses T1m ', T2f', T2r 'corresponding to', injection timings t1m ', t2f', t2r ', and injection end timings t1e', t2fe ', t2re' are set. Further, the control amount setting unit A01 receives the high alcohol concentration signal Se2 and sets the ignition timing ti2 (a value obtained by correcting the reference value according to the engine speed according to the load) in the operation region in the lean operation mode.

The injection control unit A02 performs injection driving control according to these injection data “T1m ′, T2f ′, T2r ′, injection timings t1m ′, t2f ′, t2r ′, and injection end timings t1e ′, t2fe ′, t2re ′”. The ignition control unit A03 performs ignition drive control in accordance with the ignition data “ti2”.
In this control process, the deviation of the equivalent ratio of methanol to gasoline at high alcohol concentration is taken into consideration, and the injection amount and injection pulse here are relatively larger than those at low alcohol concentration. Each end time is set earlier. In particular, as shown in FIG. 5, the higher the alcohol concentration in the blended fuel, the higher the end-of-injection time t2re 'is set to be earlier than the end-of-injection time t2re at the low alcohol concentration. Thereby, it is possible to cope with a relatively long atomization period due to a high alcohol concentration, and ignition can be reliably performed.

  Further, as shown in FIG. 5, the control amount setting unit A01 sets the ignition timings ti1 and ti1 ′ of the engine 1, and the ignition timing ti1 ′ is delayed as the alcohol concentration α of the mixed fuel is higher (higher alcohol concentration). Δta) in FIG. 5 is set. Accordingly, in consideration of the fact that the vaporization characteristic of the mixed fuel of gasoline and alcohol decreases as it is on the high alcohol concentration side, for example, as shown in FIG. 9, the higher the alcohol concentration of the mixed fuel is, the higher the alcohol concentration is. Set the ignition timing late. Thereby, the ignition to the fuel injected into the cylinder is delayed, the atomization period is ensured, the ignition can be surely performed, and the lean operation characteristics can be improved.

Further, as shown in FIG. 5, the control amount setting unit A01 determines the elapsed time Δc1 from the injection end timings t2re and t2re ′ to the ignition timings ti1 and ti1 ′ at the time of the two injections according to the alcohol concentration α of the mixed fuel. , Δc2 is set.
Here, as the alcohol concentration α is higher, that is, as shown in FIG. 5, the elapsed time Δc2 at the time of high alcohol concentration is set longer than the elapsed time Δc1 at the time of low alcohol concentration. Thereby, as the alcohol concentration of the mixed fuel is high and the alcohol concentration is high, the elapsed time Δc2 is set longer, so that the atomization period until ignition of the fuel injected into the cylinder can be sufficiently secured, and ignition can be surely performed. Lean operation characteristics can be improved.

Further, as shown in FIG. 5, the control amount setting unit A01 sets a predetermined value Δd in advance as the interval between the two pulses when setting the two injection pulses T2f, T2r, T2f ′, T2r ′, and this interval Δd. By ensuring this, the rise of the injection pressure at the second injection pulse T2r, T2r ′ is ensured, and the interval Δd is set so as to ensure the second atomization characteristic.
Further, in the two main injection modes, the two injection pulses T2f and T2r (or T2f ′ and T2r ′) are set to the same value, and this processing can facilitate the calculation.

  On the other hand, the interval between the injection end timing t2e 'in the case of two injection pulses T2f' and T2r 'at a high alcohol concentration and the reference crank angle position (here, the compression center top dead center TDC) is set to Δc2, which is larger than Δc1. Is done. Accordingly, the ignition timings ti1 and ti1 'are set to be sufficiently delayed with respect to the injection end timing t2e'. In consideration of the fact that the vaporization characteristic of the mixed fuel of gasoline and alcohol decreases as it is on the higher alcohol concentration side, for example, as shown in FIG. 9, that is, during the lean operation at the higher alcohol concentration. Sufficiently promotes fuel vaporization and maintains ignitability.

Next, the control operation of the operation control device for the internal combustion engine of FIG. 1 will be described with reference to a flowchart of an operation control routine performed by the controller 19 shown in FIG. This operation control routine is executed every predetermined time (for example, 10 ms) after the engine 1 is started.
First, in step s1, the latest engine operation information, that is, the engine speed Ne and the accelerator opening degree θa that is a load are captured. In step s2, based on the measured value from the alcohol concentration sensor 32, the alcohol concentration α of the mixed fuel of gasoline and alcohol fed into the delivery pipe 23 is read. Further, in step s3, the water temperature wt and the intake air temperature at, which are engine ambient temperatures, are captured.

When step s4 is reached, the current alcohol concentration α is compared with a high alcohol concentration determination value αa (for example, 50% alcohol), and if it exceeds the high alcohol concentration determination value αa, a high alcohol concentration signal Se2 is output, and FIG. ) Lean operation permission area setting map MAPH is selected. When the value is lower than the high alcohol concentration determination value αa, the low alcohol concentration signal Se1 is output, and the lean operation permission area setting map MAPL in FIG. 6A is selected.
Based on the selected map, whether or not the engine is in the lean operation permission range is calculated based on the current engine water temperature wt and the intake air temperature at. Thereafter, in step s5, if the previous determination result is the lean operation permission region, the process proceeds to step s6, and if not, the process proceeds to step s7.

When step s7 is reached, the stoichiometric or enriched stoichiometric air-fuel ratio A / F is reached, a correction coefficient Kα corresponding to the alcohol concentration α is calculated, and the stoichiometric or enriched target injection amount QFS {= (INJb + QA / F + Qwt) × Kα} is calculated.
Next, the routine proceeds to step s8, where the control parameter amount in the stoichiometric or enriched one-time injection mode (see the two-dot difference line in FIG. 5), that is, the injection pulse signal (corresponding to the injection amount (corresponding to the pulse width) Qsm) A valve opening signal Tsm and a predetermined injection timing tsm are set, and the process returns to the main routine (not shown). As a result, the injection pulse signal Tsm is opened at the injection timing tsm after a predetermined amount of unit crank angle is counted, and the injection amount (corresponding to the pulse width) Qsm can be injected.

If it is determined in the above step s5 that the lean operation permission range where the lean operation is possible is reached, the process reaches step s6. Here, the lean air-fuel ratio A / F in the lean operation and the correction coefficient Kα corresponding to the alcohol concentration α are obtained. The target injection amount QFR {= (INJb + QA / F + Qwt) × Kα} at the lean air-fuel ratio is calculated.
Next, in step s9, based on the current alcohol concentration α in the mixed fuel, the engine speed Ne, and the accelerator opening θa, the injection region is set once or twice using the injection number setting maps MAPNL and MAPNH. Here, as shown in FIG. 7 (a), when the alcohol concentration is low, the single injection region is selected in a relatively wide operating region, and when the alcohol concentration is high, the injection is twice as shown in FIG. 7 (b). The range is selected in a relatively wide operating range.

Next, after the 1st and 2nd injection regions in the lean operation region are set, the process proceeds to step s10. Here, the process proceeds to step s11 when it is the 2nd injection region, and to step s12 when it is the 1st injection region.
When step s12 is reached in the single injection region, here, a control amount for each parameter that affects the lean operation in the operation region (compression stroke) in the lean operation mode in the single injection is set. That is, as shown in FIG. 3 (a), in order to inject the target injection amount QFR at the lean air-fuel ratio at one time, this is set to the injection amount (corresponding to the pulse width) Q1m (Q1m ′ at high alcohol concentration). In response to this, one injection pulse T1m (T1m ′ at high alcohol concentration) and injection timing t1m (t1m ′ at high alcohol concentration) are set. Further, the ignition timings ti1 and ti1 ′ of the engine 1 are set, and the ignition timing ti1 ′ is set later (Δta in FIG. 5) as the alcohol concentration α of the mixed fuel is higher and the alcohol concentration is higher.

Further, in order to promote the vaporization of the injected fuel and maintain the ignitability, one injection pulse T1m (T1m ′ at high alcohol concentration), injection end timing t1e (t1e ′ at high alcohol concentration), and ignition timing ti1, An interval Δc1 with ti1 ′ is set.
Next, when step s13 is reached, the control amount for each parameter in the single injection mode (see FIG. 5) at the lean air-fuel ratio, that is, the injection pulse signal T1m (T1m ′ at high alcohol concentration), injection Timing t1m (t1m 'at high alcohol concentration), injection end timing t1e (t1e' at high alcohol concentration), ignition timings ti1, ti1 'are set, and the process returns to the main routine (not shown). As a result, the injection amount (corresponding to the pulse width) Q1m (Q1m ′ when the alcohol concentration is high) is injected, and an ignition process is performed at the ignition timings ti1 and ti1 ′.

On the other hand, in step s10, based on the current alcohol concentration α in the mixed fuel, the engine speed Ne, and the accelerator opening θa, it is assumed that step s11 is reached, assuming that it is the two-time injection region.
Here, the control amount for each parameter that affects the lean operation in the double injection (see FIG. 5) in the operation region (compression stroke) in the lean operation mode is set. That is, in order to divide the target injection amount QFR at the lean air-fuel ratio into two injections, that is, to achieve the target injection amount QFR (= Q2f + Q2r), the injection amount is divided into two equal parts (equivalent to pulse width) Q2f, Two injection pulses T2f and T2r (T2f ′ and T2r ′ at high alcohol concentration) corresponding to Q2r (Q2f = Q2r) are set.

  Further, two injection timings t2f and t2r (t2f 'and t2r' at high alcohol concentration) and injection end timings t2fe and t2re (t2fe 'and t2re' at high alcohol concentration) are set. Further, the ignition timings ti1 and ti1 'of the engine 1 are set, and the ignition timing ti1' is set later (Δta in FIG. 5) as the alcohol concentration α of the mixed fuel is higher and the alcohol concentration is higher. Here, the injection end timing t2re (t2re 'at high alcohol concentration) and the ignition timing ti1 (ti1' at high alcohol concentration) of the second injection pulse T2r in order to promote the vaporization of the injected fuel and maintain the ignitability. Interval Δc1 (Δc2 at high alcohol concentration) is set. This treatment can sufficiently promote fuel vaporization during lean operation at a high alcohol concentration, and maintain ignitability.

Next, when step s14 is reached, the control amount for each parameter in the two-time injection mode (see FIG. 5) at the lean air-fuel ratio, that is, the injection pulse signals T2f, T2r (T2f ′ at high alcohol concentration, T2r ′), injection timings t2f, t2r (t2f ′, t2r ′ at high alcohol concentration), ignition timings ti1, ti1 ′, etc. are set, and the process returns to the main routine (not shown).
As a result, it is possible to perform injection driving so as to perform injection twice (equivalent to pulse width) Q2f, Q2r (or Q2f ′, Q2r ′), and an ignition process is performed at the ignition timings ti1, ti1 ′.

As described above, according to the operation control device for the internal combustion engine of FIG. 1, even when the alcohol concentration α is changed when the mixed fuel of gasoline and alcohol is supplied to the engine 1, Since the control amount (injection amount, ignition timing, etc.) for each parameter is set in accordance with the change in the alcohol concentration α, the mixed fuel can be injected into the cylinder and appropriately lean burned. Can be improved.
According to the operation control apparatus for the internal combustion engine of FIG. 1, the higher the alcohol concentration α of the mixed fuel, the longer the elapsed time (Δc1 <Δc2) from the injection end timing to the timing, and the fuel injected into the cylinder It is possible to ensure a sufficient atomization period until the ignition of, to ensure ignition, and to improve the lean operation characteristics.

According to the operation control apparatus for the internal combustion engine of FIG. 1, the higher the alcohol concentration α of the mixed fuel, the slower the ignition timings ti1 and ti1 ′ (Δta in FIG. 5), and the fuel is injected into the cylinder. A sufficient atomization period before fuel ignition can be ensured, ignition can be ensured, and lean operation characteristics can be improved.
According to the operation control apparatus for the internal combustion engine of FIG. 1, the number of injections Ni of the fuel injection valve 15 can be varied a plurality of times (see FIG. 7) in accordance with the engine speed Ne and the accelerator opening θa that are the operating range of the engine 1. Because of the difference in the equivalent ratio between alcohol and gasoline, even if there is a tendency to increase the injection amount with high alcohol concentration mixed fuel, fuel injection can be divided into multiple times and only a single fuel injection valve is used This eliminates the need for a separate fuel injection valve with different specifications.

According to the operation control apparatus for the internal combustion engine of FIG. 1, as shown in FIGS. 6A and 6B, when the alcohol concentration is lower (Se1 time: MAPH) than when the alcohol concentration is high (Se2 time: MAPL). The driving range where it is determined that the lean operation is possible is set wider. For this reason, the fuel consumption can be improved by expanding the operating range in which it is determined that the lean operation is possible when the alcohol concentration is low.
According to the operation control device for the internal combustion engine of FIG. 1, the operating range in which the lean operation can be performed is appropriately corrected even in accordance with the engine water temperature wt in addition to the intake air temperature at. It can ignite and improve the lean operation characteristics.

  In the operation control device for the internal combustion engine of FIG. 1 described above, the number of injections Ni is divided into two. However, in some cases, the injection is divided into three or more times and divided injection is performed to increase the injection amount. It may be easily dealt with.

1 is a schematic configuration diagram of an engine to which an operation control device for an internal combustion engine as one embodiment of the present invention is applied. FIG. FIG. 2 is a control function block diagram of the internal combustion engine operation control device of FIG. 1. FIG. 2 is a characteristic diagram in a single injection mode performed by the operation control device of FIG. 1. FIG. 2 is a characteristic diagram in a double injection mode performed by the operation control device of FIG. 1. FIG. 2 is a comparison diagram for each of the 1 and 2 injection modes at low and high alcohol concentrations performed by the operation control device of FIG. 1. In the lean operation permission area setting map used by the operation control device of FIG. 1, (a) is for a low alcohol concentration, and (b) is for a high alcohol concentration. FIG. 1 is a map for setting the first and second injection ranges used by the operation control apparatus of FIG. 1, (a) is for a low alcohol concentration, and (b) is for a high alcohol concentration. It is a flowchart of the operation control routine which the controller of the operation control apparatus of FIG. 1 uses. It is a methanol concentration characteristic diagram in a mixed fuel of gasoline and alcohol, and is also used for explanation of the configuration of the present invention.

Explanation of symbols

1 Engine 15 Injector 16 Spark plug (ignition means)
19 Controller (Operation control device)
31 Accelerator opening sensor 32 Alcohol concentration sensor (alcohol concentration detection means)
37 Accelerator opening sensor 41 Intake temperature sensor 42 Water temperature sensor α Alcohol concentration at Intake temperature Δc1, Δc2 Elapsed time ti1 Ignition timing wt Water temperature Tsm Injection pulse (control amount for each parameter)
t1m, t2f, t2r Injection timing (control amount for each parameter)
t1e, t2fe, t2re Injection end timing (control amount for each parameter)
A0 Control means A01 Control amount setting part A02 Injection control part A03 Ignition control part A1 Target injection amount setting means A2 Driving range determination means

Claims (5)

A fuel injection valve for injecting a mixed fuel of gasoline and alcohol into a cylinder of the internal combustion engine;
Ignition means for igniting the mixed fuel injected from the fuel injection valve in the cylinder;
Alcohol concentration detection means for detecting the alcohol concentration in the mixed fuel;
Based on the alcohol concentration detected by the alcohol concentration detection means, an operating range determination means for determining whether or not the internal combustion engine is in an operating range where lean operation is possible;
When the operation region determination unit determines that the lean operation is possible, the higher the alcohol concentration in the mixed fuel, the longer the period from the injection end timing of the fuel injection valve to the ignition timing of the ignition unit. Control means for controlling at least one of the injection timing of the fuel injection valve or the ignition timing of the ignition means,
An operation control device for an internal combustion engine, comprising: A fuel injection valve for injecting a mixed fuel of gasoline and alcohol into a cylinder of the internal combustion engine;
Ignition means for igniting the mixed fuel injected from the fuel injection valve in the cylinder;
Alcohol concentration detection means for detecting the alcohol concentration in the mixed fuel;
Based on the alcohol concentration detected by the alcohol concentration detection means, an operating range determination means for determining whether or not the internal combustion engine is in an operating range where lean operation is possible;
Control means for controlling the ignition timing of the ignition means to be delayed as the alcohol concentration in the mixed fuel is higher when the operation area determination means determines that the lean operation is possible.
An operation control device for an internal combustion engine, comprising: The operation control device for an internal combustion engine according to claim 1 or 2,
The number of fuel injections of the fuel injection valve can be set according to the alcohol concentration, and the higher the alcohol concentration, the wider the operating range in which the lean operation can be performed by injecting the fuel injection valve a plurality of times. An operation control apparatus for an internal combustion engine, characterized in that The internal combustion engine operation control device according to claim 1, 2, or 3,
The operating range determination means is configured to perform a determination according to a low alcohol concentration lower than a predetermined alcohol concentration and a high alcohol concentration higher than the low alcohol concentration, and the lean operation is possible. The operation control device for an internal combustion engine, wherein the operation range to be determined is set wider at the low alcohol concentration than at the high alcohol concentration. The operation control apparatus for an internal combustion engine according to any one of claims 1 to 4,
The operation control device for an internal combustion engine, wherein the operation region determination means further determines whether or not the operation region is an operation region in which the lean operation can be performed using an intake air temperature and a water temperature of the internal combustion engine.

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