JP5658204B2 - Control device for in-vehicle internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an in-vehicle internal combustion engine, and more particularly to a control device for an in-vehicle internal combustion engine that uses various fuels composed of gasoline and alcohol (ethanol) and drives the drive wheels by changing the output with a transmission.

  Recently, various control devices for an internal combustion engine using various fuels have been proposed, and examples thereof include the technique described in Patent Document 1 below. In the technique described in Patent Document 1, the determination vehicle speed and the determination output torque, which are boundary values for dividing the stepped control region and the continuously variable control region of the speed change mechanism in the hybrid vehicle, become smaller as the mixing ratio of alcohol (ethanol) increases. By controlling so that it becomes, it is comprised so that the favorable fuel consumption performance according to the mixing rate of alcohol may be obtained.

JP 2011-6065 A

  In the technique described in Patent Document 1, the configuration as described above controls the fuel efficiency to be improved even when the type of fuel to be supplied is changed, but it is not limited to that. It was.

  That is, it is possible to improve thermal efficiency while avoiding knocking by using various fuels, and to improve fuel efficiency by controlling the gear ratio, but the technique described in Patent Document 1 suggests anything about it. It was not a thing.

  To explain it, it is generally known that the fuel efficiency (thermal efficiency) of an internal combustion engine using gasoline as fuel is higher in a high load range than in a low load range at all revolutions. This is mainly due to the fact that the pump loss increases as the load decreases. It is also known that in the high load range, the ignition timing must be retarded by knocking, so that a slight reduction in fuel efficiency occurs.

  In a fuel-efficient engine with a high compression ratio, it is also known that the generated torque decreases because knocking occurs mainly in a low rotation range. In other words, to avoid knocking, select whether to operate with low torque by retarding the ignition timing and lowering the thermal efficiency, or to operate with low torque by reducing the effective compression ratio and reducing the amount of intake air I have to.

  As is well-known, a high-octane component separated in a low-rotation and high-load range is used in an internal combustion engine that can supply various fuels consisting of alcohol-containing gasoline separated into a high-octane component and a low-octane component. By doing so, higher torque can be obtained.

  Generally, the gear ratio (transmission ratio) of the transmission of the vehicle is set so that acceleration and running performance are sufficient by the balance between the output performance of the internal combustion engine and the vehicle weight. The rotational speed at the same vehicle speed becomes lower as the gear stage is higher (the transmission ratio is smaller). Since the output on the axle is the number of revolutions multiplied by a load (torque), when accelerating from a certain point, the higher the number of revolutions, the lower the load, and the lower the number of revolutions. The load becomes high.

  That is, in consideration of acceleration performance, it is desirable to set a higher gear (small gear ratio) as the maximum load of the internal combustion engine is higher. In addition, when considering fuel efficiency, the use of a high load range can be improved because the effects of pumping loss are reduced, and high friction (mechanical loss) in the high rotation range can be avoided. It is advantageous to use a small transmission ratio) setting.

  Accordingly, an object of the present invention is to solve the above-described problems, to improve thermal efficiency and fuel efficiency while avoiding knocking using various fuels, and to further improve fuel efficiency by controlling the gear ratio. Another object of the present invention is to provide a control device for an on-vehicle internal combustion engine.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a valve opening / closing timing variable mechanism capable of changing an opening / closing timing of the intake valve, ignition means, and a fuel capable of injecting various fuels mainly composed of gasoline. An air-fuel mixture generated by mixing fuel injected from at least one of the first and second injectors with intake air, and a second injector capable of injecting alcohol fuel having an octane number higher than that of the various fuels; Is detected by the piston in the combustion chamber, and is ignited and burned by the ignition means to produce an output, and in the control device of the on-vehicle internal combustion engine that drives the drive wheels by shifting with the transmission, the alcohol concentration of the various fuels is detected. Whether or not the probability of occurrence of knocking is greater than or equal to a threshold value based on the alcohol concentration detection means to perform and at least the engine speed and engine output torque Knock determination means for determining, target compression ratio calculation means for calculating a target compression ratio based on the detected alcohol concentration when it is determined that the probability of occurrence of knocking is greater than or equal to a threshold value, and the calculated an intake valve closing timing correction means for correcting the closing timing of the intake valve the operating the valve opening and closing timing changing mechanism so that the target compression ratio, based on the characteristics of the output that will be set for the engine speed controls the gear ratio before Symbol transmission, when the alcohol fuel was injected from the second injector, based on the characteristic of the output with respect to possible occurrence output by obtained by injecting the alcohol fuel Gear ratio control means for selecting a gear ratio that reduces the engine speed is provided.

  In the on-vehicle internal combustion engine control apparatus according to claim 2, whether or not the output of the internal combustion engine can reach a target output when the intake valve closing timing is corrected by the intake valve closing timing correction means. When the output determining means and the output determining means determine that the output cannot reach the target output, it is determined whether or not the alcohol concentration can be increased. An alcohol concentration increasing means for increasing is provided.

  In the control apparatus for an on-vehicle internal combustion engine according to claim 3, the first injector includes an injector that directly injects the various fuels into the combustion chamber, and the second injector is provided at an intake port in front of the combustion chamber. It comprised so that it might consist of the injector which injects the said alcohol.

  In the on-vehicle internal combustion engine control apparatus according to claim 1, the alcohol concentration of the various fuels mainly composed of gasoline is detected, and the probability of occurrence of knocking from at least the engine speed and the engine output torque is a threshold value. When it is determined whether or not and the probability of occurrence of knocking is determined to be equal to or higher than a threshold value, the target compression ratio is calculated based on the detected alcohol concentration, and the calculated target compression ratio is obtained. Since the valve opening / closing timing variable mechanism that can change the opening / closing timing of the intake valve is operated to correct the closing timing of the intake valve, it is possible to realize an internal combustion engine with low fuel consumption and high output by using alcohol as fuel. Can do.

  In other words, since the target compression ratio is calculated according to the alcohol concentration and the closing timing of the intake valve is corrected so as to be the calculated target compression ratio, the alcohol fuel can be used even when the supply of alcohol is restricted. An internal combustion engine with low fuel consumption and high output can be realized while suppressing the occurrence of knocking due to the restriction of the supply of the engine.

To explain that, in an Otto cycle where the expansion ratio is equal to the volume ratio (compression ratio) for compressing intake air in the operation of the internal combustion engine , the thermal efficiency increases as the compression ratio increases. Knocking will occur. Moreover, since the pump loss increases as the load decreases, the thermal efficiency in the low load region is lower than that in the high load region.

  In that respect, while increasing the mechanical compression ratio, the intake valve closing angle is delayed to reduce the intake amount, and the effective compression ratio is suppressed in the same manner as the Otto cycle, so that knocking is avoided and the thermal efficiency is substantially controlled. An Atkinson cycle (also called “Miller cycle”) in which an expansion ratio (mechanical compression ratio) is increased is known.

  Normally, the Atkinson cycle is controlled so that the intake air amount is reduced by delaying the closing angle of the intake valve and discharging the once sucked air (hereinafter referred to as “slow closing Atkinson”), but the closing angle of the intake valve The intake amount can also be controlled by speeding up (hereinafter referred to as “early closing Atkinson”). In view of this point, in the present invention, the closing timing of the intake valve is corrected, that is, the closing timing is delayed to be delayed closing Atkinson, or the advanced timing is advanced to close Atkinson. In combination with this, it is possible to realize an internal combustion engine with low fuel consumption and high output.

Further, to control the gear ratio of the speed change device based on the characteristics of the output of the internal combustion engine that will be set for the engine speed, when jetted alcohol fuel from the second injector, the characteristics of the output of the internal combustion engine On the basis of this, the speed ratio is selected so that the engine speed decreases with respect to the output that can be generated by injecting the alcohol fuel, so that the maximum torque of the low rotation can be increased, and the high gear It is possible to achieve a step (small gear ratio) or to adjust the final gear ratio (final reduction ratio) to use a high gear as a whole, thereby resulting in high rotation / low load with poor fuel consumption. A higher gear (smaller gear ratio) can be selected without using a region, and fuel efficiency can be further improved.

  In the on-vehicle internal combustion engine control apparatus according to claim 2, when the closing timing of the intake valve is corrected, it is determined whether or not the output of the internal combustion engine can reach the target output, and it is determined that the target output can be reached. If not, it is determined whether or not the alcohol concentration can be increased. When it is determined that the alcohol concentration can be increased, the alcohol concentration is increased. Therefore, as long as it is determined that the alcohol concentration can be increased, the internal combustion engine It becomes possible to make the engine output reach the target output.

  In the control apparatus for an on-vehicle internal combustion engine according to claim 3, the first injector includes an injector that directly injects various fuels into the combustion chamber, and the second injector injects alcohol into an intake port in front of the combustion chamber. In addition to the effects described above, the first injector is an injector that directly injects various fuels into the combustion chamber, so that abnormal combustion can be avoided by the latent heat of the injected various fuels, and the second injector By using an injector that injects alcohol into the intake port, the accuracy and cost of components such as a pressure pump can be reduced, and the configuration can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an overall control apparatus for an onboard internal combustion engine according to an embodiment of the present invention. It is a block diagram which shows the operation | movement of ECU shown in FIG. 1 functionally. Fig. 2 is a flowchart showing more specifically the operation of the ECU shown in Fig. 1. 3 is an explanatory diagram showing calculation of the occurrence probability of knocking referred to in the processing of the flow chart of FIG. 3 is an explanatory diagram showing the characteristics of the effective compression ratio with respect to the alcohol concentration mentioned in the processing of the flow chart. FIG. 4 is an explanatory diagram showing characteristics of the effective compression ratio with respect to the intake valve closing timing, which is referred to in the processing of the flow chart of FIG. 3. FIG. 4 is an acupressure diagram of the Atkinson cycle, which is referred to in the process of the flow chart of FIG. FIG. 4 is an explanatory diagram showing intake valve closing timing referred to in the processing of the flow chart of FIG. 3. 3 is an explanatory diagram showing the effect of the processing of the flow chart. 3 is a block diagram showing the operation of the second ECU shown in FIG. 1, which is executed in parallel with the processing of the flow chart of FIG. It is explanatory drawing which shows the characteristic of the gear ratio (speed ratio) with respect to an engine speed and load mentioned by the process of the block diagram of FIG. FIG. 11 is also an explanatory diagram showing the characteristics of the gear ratio (transmission ratio) with respect to the engine speed and the vehicle speed, similarly referred to in the processing of the block diagram of FIG. FIG. 3 is a flowchart showing more specifically the operation of the second ECU shown in FIG. 1. FIG. FIG. 14 is a flow chart of the modified example of FIG. 13 showing the operation of the second ECU shown in FIG. 1 more specifically.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment for implementing a control device for an on-vehicle internal combustion engine according to the invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic view generally showing a control apparatus for an in-vehicle internal combustion engine according to an embodiment of the present invention .

  In FIG. 1, reference numeral 10 denotes a four-cylinder (cylinder) four-cycle internal combustion engine (only one cylinder is shown; hereinafter referred to as “engine”) mounted on a vehicle (not shown). In the engine 10, the intake air drawn from an air cleaner (not shown) flows through the intake pipe 12, the flow rate is adjusted by the throttle valve 14, the intake manifold 16, and two intake valves (only one is shown) 20. When the valve is opened (opened), it flows into the combustion chamber 22.

  The throttle valve 14 is mechanically disconnected from the accelerator pedal 24 disposed on the vehicle driver's seat floor, and the opening and closing of the throttle valve 14 is controlled by a DBW (Drive By Wire) mechanism 26. That is, the throttle valve 14 is connected to an actuator (electric motor) 26a and is opened and closed by being driven by the actuator 26a.

  A first injector (fuel injection valve) 30 is disposed at a position facing the combustion chamber 22, and a second injector (fuel injection valve) 32 is disposed in the intake port 16 a in front of the intake valve 20.

  Various fuels stored in the main fuel tank 34 are pumped to the first injector 30 by a main fuel pump 34 a disposed inside the tank, and are pumped through the fuel supply pipe 36. The first injector 30 directly injects the various fuels fed under pressure into the combustion chamber 22. Hereinafter, the first injector 30 is also referred to as a “direct injection injector”.

  As the multi-fuel, it is planned to use a fuel having a relatively low alcohol concentration, such as a mixed fuel of gasoline and ethanol (ethyl alcohol), specifically, a mixed fuel (E10) of 90% gasoline and 10% ethanol.

  On the other hand, the various fuels stored in the main fuel tank 34 are pumped up by the sub fuel pump 34b and sent to the gas-liquid separator 42 through the pipe 40, where they are heated and cooled to be separated into alcohol components and other components.・ Extracted.

  The separated alcohol component is stored in the sub fuel tank 44 as alcohol fuel having a certain range of alcohol concentration, and the other components are returned to the main fuel tank 34 via the pipe 46. The alcohol fuel stored in the sub fuel tank 44 is pumped up by a fuel pump 44 a disposed inside the tank, and is pumped to the second injector 32 through the fuel supply pipe 50.

  The second injector 32 injects the pumped alcohol fuel into the intake port 16a. Hereinafter, the second injector 32 is also referred to as a “port injector”. The injected alcohol fuel flows into the combustion chamber 22 when the intake valve 20 is opened.

  The direct injection injector 30 or the port injector 32 is electrically connected to an ECU (Electronic Control Unit) 54 through a driver (drive circuit; shown in FIG. 2) 52 and indicates a valve opening (opening) time from the ECU 54. When the drive signal is supplied through the driver 52, the valve is opened, and fuel corresponding to the valve opening time is injected into the combustion chamber 22 or the intake port 16a. The injected fuel is mixed with the inflowing air to generate an air-fuel mixture.

  A spark plug 56 is disposed in the combustion chamber 22. The spark plug 56 is connected to an ignition device 60 such as an igniter. When an ignition signal is supplied from the ECU 54 via the driver 52, the ignition device 60 generates a spark discharge between the electrodes of the spark plug 56. The air-fuel mixture is ignited and combusted thereby, and drives the piston 62 slidably accommodated in the combustion chamber 22 downward.

  Inside the cylinder block 64 in which the combustion chamber 22 is formed, a crankshaft (not shown) that is connected to the piston 62 and converts the vertical motion of the piston 62 into rotational motion is accommodated.

  Exhaust gas (exhaust gas) generated by the combustion flows from the exhaust manifold 74 to the exhaust pipe 76 through the exhaust port 72 when two exhaust valves (only one is shown) 70 are opened. The exhaust pipe 76 is provided with a catalyst device (not shown). Exhaust gas is discharged to the atmosphere outside the engine after removing harmful components such as HC, CO, and NOx by the catalyst device.

  The cylinder head 64 a is provided with a valve opening / closing timing variable mechanism (hereinafter referred to as “VTC”) 80. The VTC 80 is a hydraulic motor that can change the timing for opening and closing the combustion chamber of the intake valve, which is defined as the phase angle of the camshaft with respect to the crankshaft by driving the camshaft via hydraulic pressure. In addition to the VTC 80, a mechanism capable of changing the opening / closing phase angle and the lift amount of the intake cam 80b according to a plurality of cams (cams) may be provided.

  A crank angle sensor 82 composed of a pulsar and a magnetic pickup is disposed in the vicinity of the camshaft of the engine 10, and a cylinder discrimination signal and a TDC signal indicating a TDC (top dead center) of each cylinder or a crank angle in the vicinity thereof, A CRK signal obtained by subdividing the TDC signal is output.

  An air flow meter 84 having a temperature detection element is disposed in the vicinity of the air cleaner, and outputs a signal corresponding to the amount of air (intake air) Q taken from the air cleaner and the intake air temperature TA.

  A MAP sensor 86 is disposed downstream of the throttle valve 14 in the intake pipe 12 to output a signal indicating the intake pipe pressure PBA in absolute pressure, and a throttle opening sensor 90 is disposed in the DBW mechanism 26. A signal corresponding to the position (throttle opening TH) is output.

  A water temperature sensor 92 is disposed in a cooling water passage (not shown) formed in the crankcase 64a of the engine 10 and outputs a signal corresponding to the engine cooling water temperature (engine temperature) TW. 94 is arranged to output a signal corresponding to vibration generated in the engine 10 due to knocking.

  In the exhaust system, an A / F sensor (wide area air-fuel ratio sensor) 96 is arranged upstream of the catalyst device, and in a wide range from the stoichiometric air-fuel ratio to rich or lean, in other words, the actual air concentration. A signal indicating the fuel ratio KACT is output.

Main fuel tank 34 and the gas-liquid separator 4 2 a wide fuel to the conduit 40 through the conduit 40 is disposed alcohol sensor 100 to be connected, a wide fuel stored in the main fuel tank 34 and more specifically In addition to outputting a signal indicating the alcohol concentration, a level sensor 102 is disposed in the sub fuel tank 44, and the level (liquid level height) of the alcohol fuel stored in the sub fuel tank 44, in other words, the remaining amount of alcohol fuel. A signal indicating is output.

  An accelerator opening sensor 104 is provided in the vicinity of the accelerator pedal 24, and outputs a signal corresponding to the accelerator opening AP indicating the amount by which the driver depresses the accelerator pedal. A vehicle speed sensor 106 is provided in the vicinity of a drive shaft (not shown), and outputs a pulse signal per predetermined angular rotation of the drive shaft.

  The output of the sensor group described above is input to the ECU 54. The ECU 54 includes a microcomputer and includes a CPU, a ROM, a RAM, an I / F, and the like. The ECU 54 measures (detects) the engine speed NE and the vehicle speed V by measuring the time interval between the output of the crank angle sensor 82 (CRK signal) and the output of the vehicle speed sensor 106 among the input signals.

  FIG. 2 is a block diagram functionally showing the operation of the ECU 54.

  In the ECU 54, the CPU 54a searches for an appropriate characteristic (map) from the engine speed NE and the engine load in the calculation unit 54a1 based on the sensor output input via the I / F 54b, and the fuel injection amount TOUT to be supplied to the engine 10 Is calculated.

  That is, the CPU 54a calculates the basic fuel injection amount TIM in accordance with the engine speed NE and the engine load, and in the air / fuel ratio feedback control for controlling the detected air / fuel ratio KACT to the target air / fuel ratio KCMD, The fuel injection amount is calculated by calculating the fuel ratio by correcting the basic fuel injection amount by calculating the fuel ratio correction coefficient (air-fuel ratio feedback correction coefficient) KAF and further calculating other correction coefficients such as the alcohol concentration correction coefficient (alcohol concentration learning value) KREFBS. TOUT is calculated.

The CPU 54a drives the direct injection injector 30 based on the calculated fuel injection amount TOUT. The alcohol concentration correction coefficient KREFBS is learned using the air-fuel ratio correction coefficient KAF, and the alcohol concentration is learned.

Incidentally, since the alcohol sensor 100 is provided in this embodiment, without using any alcohol concentration correction coefficient K REFBS described above, it may be calculated fuel injection amount TOUT from the output of the alcohol sensor 100 .

  Further, the CPU 54a calculates (sets) the target phase angle of the intake cam 80b of the VTC 80, that is, the opening / closing timing of the intake valve 20 in the target phase calculation unit 54a2, and drives the actuator of the VTC 80 so as to be the calculated target phase angle. At the same time, the ignition timing calculation unit 54a3 calculates the ignition timing IG to be supplied to the engine 10 in accordance with the engine speed NE and the engine load, and controls ignition by the spark plug 56 via the ignition device 60 based on the ignition timing IG.

The CPU 54a further calculates the target throttle opening THD in the throttle opening calculation unit 54a4. First, the CPU 54a calculates the required torque PCMD as follows.
PCMD = k · PSE / NE
The required output of the engine 10 obtained by searching a preset characteristic (map) from the above: k: constant, PSE: accelerator opening AP and engine speed NE is shown.

Next, the CPU 54a determines the target throttle opening THD so as to be the calculated required torque PCMD, and drives the actuator 26a of the DBW mechanism 26 so as to be the determined target throttle opening THD.

  Returning to the description of FIG. 1, the engine 10 is connected to a transmission (continuously variable transmission; hereinafter referred to as “CVT”) 120 via a torque converter and a forward / reverse switching mechanism (both not shown). The

  Although not shown, the CVT 120 is made of a drive pulley disposed on the transmission input shaft, a driven pulley disposed on the transmission output shaft that is also received in parallel with the transmission input shaft, and a metal made around the drive pulley. Belt (endless flexible member).

  The CVT 120 adjusts the belt wrapping radius by moving the drive driven pulley on the shaft with the hydraulic pressure supplied from the hydraulic pressure supply circuit and narrowing the belt, thereby making the output (rotation) of the engine 10 stepless. The speed is changed at a gear ratio (gear ratio) and transmitted to drive wheels (not shown).

  The direction of rotation of the drive wheel is determined by a forward / reverse switching mechanism. Note that details of the CVT 120 are described in, for example, Japanese Patent Application Laid-Open No. 2011-196390 filed by the present applicant, and the description is thus stopped.

  Operations of the CVT 120, the torque converter, the forward / reverse switching mechanism, the hydraulic pressure supply circuit, and the like are similarly controlled by a second ECU (electronic control unit) 122 composed of a microcomputer. The second ECU 122 is communicably connected to the ECU 54.

  FIG. 3 is a flowchart showing the operation of the ECU 54 more specifically.

  In the following, the engine speed NE detected in S10 and the calculated required torque PCMD are read, and the process proceeds to S12 to detect the alcohol concentration of various fuels currently used (stored in the main fuel tank 34). To do. That is, the alcohol concentration of various fuels stored in the main fuel tank 34 is detected from the output of the alcohol sensor 100.

Next, in S14, it is determined whether or not the occurrence probability of knocking (probability of occurrence of knocking) is greater than or equal to the threshold value b . The knocking occurrence probability means a value (for example, point a) obtained by searching the characteristic (map) shown in FIG. 4 with the engine speed NE and the engine torque.

  Therefore, the determination in S14 is made by comparing the value obtained by the search (for example, point a) with the threshold value b and determining whether or not the value is greater. The determination in S14 is performed by selecting the corresponding threshold value b from the required torque PCMD read in S10 and comparing it with the search value.

  Returning to the explanation of the flow chart of FIG. 3, when the result in S14 is negative and it is determined that the knocking occurrence probability is not equal to or higher than the threshold value, the process proceeds to S16, and the target phase angle of the intake cam 80b of the VTC 80 is changed to the normal phase angle. (In other words, the engine 10 is set to a phase angle corresponding to the valve opening / closing timing at which the engine 10 is operated at the compression ratio of the ordinary Otto cycle (the compression ratio and the expansion ratio are equal)), and the VTC 80 is operated so as to be the phase angle. Let

  On the other hand, when the result in S14 is affirmative and it is determined that the knocking occurrence probability is equal to or higher than the threshold value, the process proceeds to S18, and a compression ratio at which knocking does not occur is selected. That is, the effective compression ratio is selected by searching the characteristic (map) shown in FIG. 5 based on the alcohol concentration detected in S12, in other words, the target compression ratio is calculated.

Next, in S20, the target phase angle of the intake cam 80b of the VTC 80 is set according to the characteristic (map) shown in FIG. 6 so that the effective compression ratio (target compression ratio) selected in S18 is reached (lowered). That is, the valve closing timing of the intake valve 20 is corrected by operating the VTC 80, more specifically, the valve timing is advanced and changed to the valve closing timing of the early closing Atkinson.

  FIG. 7 shows the characteristics of the early closing Atkinson in comparison with the Otto cycle (broken line).

More specifically, closing timing of on the basis of the effective compression ratio selected by searching the characteristics shown in FIG. 6 intake valves 20 at S18, any value between ABDC-20 degrees ABDC-80 degrees Set to.

  FIG. 8 shows the opening / closing timing of the intake valve 20 (and the exhaust valve 70). In the process of S20, the closing timing of the intake valve 20 is set to an arbitrary value between ABDC-80 degrees (ATDC 100 degrees) and ABDC-20 degrees (ATDC 160 degrees), in other words, the bottom dead center BDC of the intake stroke. Set to advance more.

  As mentioned at the beginning, in addition to the early closing Atkinson, the Atkinson cycle has a late closing Atkinson in which the intake air amount is reduced by discharging the air once sucked by delaying the closing angle of the intake valve. Since an effect can be obtained, in the process of S20, the VTC 80 is operated, and the closing timing of the intake valve 20 is retarded so that the delayed closing Atkinson is possible.

  Returning to the description of the flow chart of FIG. 3, the process then proceeds to S22, in which it is determined whether the output of the engine 10 can reach the target output.

  On the other hand, when the result in S22 is negative and it is not determined that the target output can be reached, the process proceeds to S24, and the remaining amount of alcohol is detected. That is, the remaining amount of alcohol fuel stored in the sub fuel tank 44 is detected from the output of the level sensor 102.

  Next, the process proceeds to S26, in which it is determined whether or not the detected remaining amount of alcohol fuel is greater than a predetermined value, in other words, greater than or equal to the level that can be supplied to the engine 10, and if affirmative, the process proceeds to S28 and stored in the sub fuel tank 44. The alcohol fuel is injected from the port injector 32 to the intake port 16a (in other words, the alcohol concentration of the fuel supplied to the engine 10 is increased). Next, the process proceeds to S12 and the above processing is repeated.

  On the other hand, when the result in S26 is negative, the program proceeds to S30, in which the engine 10 is operated under conditions where the ignition timing is adjusted and knocking does not occur. That is, the ignition timing is controlled based on the output of the knocking sensor 94 so that knocking does not occur.

  FIG. 9 is an explanatory diagram showing the effect of the above processing.

  Even if E10 ethanol fuel having a relatively low alcohol concentration is used as the multi-fuel, if the occurrence probability of knocking is determined to be greater than or equal to the threshold value in S14 of the flow chart of FIG. Ignition while avoiding knocking (compared to the case where it is judged that it is not above the threshold value and proceeds to S16 and operating in the normal Otto cycle) by driving with early closing Atkinson and lowering the effective compression ratio It can be seen from the figure that the engine 10 can be burned with high thermal efficiency without delaying the timing.

  That is, in an Otto cycle in which the volume ratio (compression ratio) for compressing intake air is equal to the expansion ratio, the thermal efficiency increases as the compression ratio is increased. However, in an ordinary gasoline engine, knocking occurs if the compression ratio is increased too much. Moreover, since the pump loss increases as the load decreases, the thermal efficiency in the low load region is lower than that in the high load region.

  In that respect, while increasing the mechanical compression ratio, the intake valve closing timing is advanced (or retarded) to reduce the intake air amount, while suppressing the effective compression ratio in the same manner as the Otto cycle and substantially avoiding knocking. By using the Atkinson cycle that increases the expansion ratio (mechanical compression ratio) that governs the thermal efficiency, the thermal efficiency in the low load range can be improved. Combined with the use of alcohol as the fuel, the low fuel consumption and high output engine 10 can be achieved. Can be realized. In FIG. 9, “load factor” means a ratio to the fully open throttle opening (WOT).

  FIG. 10 is a block diagram showing the operation of the second ECU 122 executed in parallel with the processing of the ECU 54 shown in FIG. 3, more specifically, the operation of the CPU 122a. The second ECU 122 executes the illustrated process while communicating with the ECU 54.

  As described above, it is generally known that the fuel efficiency (thermal efficiency) of an engine using gasoline as fuel is higher in a high load range than in a low load range at all revolutions. Further, as shown in FIG. 11, the engine speed NE at the same vehicle speed becomes lower as the gear position becomes higher (the gear ratio becomes smaller).

  That is, as shown in FIG. 12, when the acceleration performance is taken into consideration, the higher the maximum load of the engine 10, the higher the gear position (small gear ratio) can be set. In addition, when considering fuel efficiency, the use of a high load range can be improved because the effect of pumping loss is reduced, and high friction in the high rotation range (mechanical loss) can be avoided. It is more advantageous to set it so that the gear ratio is reduced.

  Therefore, in this embodiment, various fuels are used to avoid knocking and improve thermal efficiency and fuel efficiency, and control the gear ratio (gear ratio) to further improve fuel efficiency.

  10 will be described based on the above assumption. In the second ECU 122, the CPU 122a includes a request output calculation unit 122a1, a gear ratio selection control unit 122a2, and a gear ratio determination unit 122a3. The request output calculation unit 122a1 includes the accelerator opening sensor 104 and the vehicle speed. A predetermined output set in advance is searched from the accelerator opening AP detected by the sensor 106 and the vehicle speed V (in other words, the required acceleration force), and the required output is calculated as the accelerator opening.

  Next, the CPU 122a selects a gear ratio (transmission ratio) according to the illustrated characteristics (a) and (b) stored in the gear ratio selection control unit 122a2, and the fuel efficiency is good in the gear ratio selected in the gear ratio determination unit 122a3. The gear ratio is finally determined by the range.

  In other words, the speed ratio is set so that the engine speed NE decreases based on the torque (output) characteristic (b) of the engine 10 set for the engine speed NE as shown in the gear ratio selection control unit 122a2. Control, more specifically, control is performed so that the gear ratio is decreased so that the engine speed NE is decreased.

  Next, the CPU 122a determines the gear ratio, the engine speed NE, and the engine torque in the gear ratio determination unit 122a3.

  FIG. 13 is a flowchart showing the process of FIG. 10 more specifically.

  In the following description, in S100, a predetermined characteristic set in advance is calculated from the accelerator opening AP and the vehicle speed V (required acceleration force) to calculate a required output, and the process proceeds to S102 to select a gear ratio (transmission ratio) for the time being. In S104, the engine speed NE and torque (load) are determined from the operation map (characteristic (b) of the gear ratio selection control unit 122a2 in FIG. 10).

  Next, the process proceeds to S106, and the remaining amount of alcohol fuel stored in the sub fuel tank 44 is detected in the same manner as the processing of S26 and S28 in the flow chart of FIG. Then, it is determined whether or not alcohol fuel can be supplied to the engine 10.

  When the result in S106 is affirmative, the program proceeds to S108, and a torque that can be generated at the alcohol concentration (ethanol ratio) when alcohol fuel is injected from the port injector 32 to the intake port 16a is calculated.

  Next, returning to S102, the smallest possible gear ratio (high gear side) is selected again from the characteristic (b) of the gear ratio selection control unit 122a2 in FIG. The above process is repeated in S106, in other words, until it is determined that it is impossible to increase the amount of alcohol fuel supplied to the engine 10.

  On the other hand, when the result in S106 is negative, the program proceeds to S110, where the selected gear ratio is determined, and the program proceeds to S112, in which the engine 10 and the CVT 120 are operated, that is, the operations of the engine 10 and the CVT 120 are controlled. Needless to say, the alcohol fuel whose amount can be increased is injected from the port injector 32 when the processes of S106 and S108 are performed.

  FIG. 14 is a flow chart similar to FIG. 13, showing a modification of the processing of FIG.

  In the following, the required output is calculated in S200, the gear ratio is temporarily set in S202, and then the process proceeds to S204, where the higher torque / lower engine speed NE is obtained from the characteristic (b) of the gear ratio selection control unit 122a2 in FIG. It is determined whether or not the output of the engine 10 (in the engine 10) is possible. If the result is affirmative, the process proceeds to S206, and the operation of the CVT 120 is controlled so that the gear ratio is increased, that is, the gear ratio is decreased.

  Next, the routine proceeds to S208, where the temporarily set gear ratio is determined, and the routine proceeds to S210, where the engine 10 and the CVT 120 are operated.

As described above, in this embodiment, the valve opening timing variable mechanism (VTC) 80 capable of changing the opening / closing timing of the intake valve 20, ignition means (ignition device 60, ignition plug 56), and gasoline are the main components. A first injector (direct injector) 30 capable of injecting a variety of fuels, and a second injector (port injector) 32 capable of injecting an alcohol fuel having an octane number higher than that of the various fuels. An air-fuel mixture produced by mixing fuel injected from at least one of the injectors with intake air is compressed by the piston 62 in the combustion chamber 22 and ignited and burned by the ignition means to produce an output, and a transmission (CVT) In the control device for an on-vehicle internal combustion engine (engine) 10 that drives the drive wheels by shifting at 120, the multi-fuel alcohol Whether the probability of occurrence of knocking is greater than or equal to a threshold value based on alcohol concentration detection means (alcohol sensor 100, ECU 54, S12) for detecting the degree, and at least engine speed (engine speed) NE and engine output torque (engine torque) Knocking determination means (ECU 54, S14) for determining whether or not, and when it is determined that the probability of occurrence of knocking is equal to or greater than a threshold value, a target compression ratio (effective compression ratio) is calculated based on the detected alcohol concentration Target compression ratio calculating means (ECU 54, S18) for operating the valve opening / closing timing variable mechanism so as to achieve the calculated target compression ratio to correct the closing timing of the intake valve, more specifically, advance angle or a retarded to the intake valve closing timing correction means (ECU54, S20), the exit-Ru is set for the engine speed Controls the gear ratio before Symbol transmission based on the characteristics, when said alcohol fuel is injected from the second injector, based on the characteristics of the output, it can be generated by obtained by injecting the alcohol fuel Since it is configured to include a gear ratio control means (second ECU 122, S100 to S110) for selecting a gear ratio at which the engine speed is reduced with respect to an accurate output , the use of alcohol as fuel reduces fuel consumption and increases fuel efficiency. The output engine 10 can be realized.

  In other words, since the target compression ratio is calculated according to the alcohol concentration and the closing timing of the intake valve is corrected so as to be the calculated target compression ratio, the alcohol fuel can be used even when the supply of alcohol is restricted. An internal combustion engine with low fuel consumption and high output can be realized while suppressing the occurrence of knocking due to the restriction of the supply of the engine.

  To explain that, in the Otto cycle where the expansion ratio is equal to the volume ratio (compression ratio) for compressing intake air during engine operation, the thermal efficiency increases as the compression ratio increases, but in ordinary gasoline engines, knocking occurs when the compression ratio is increased too much. Will occur. Moreover, since the pump loss increases as the load decreases, the thermal efficiency in the low load region is lower than that in the high load region.

  In that respect, while increasing the mechanical compression ratio, the intake valve closing angle is delayed to reduce the intake amount, and the effective compression ratio is suppressed in the same manner as the Otto cycle, so that knocking is avoided and the thermal efficiency is substantially controlled. There is known an Atkinson cycle in which an expansion ratio (mechanical compression ratio) is increased.

  Normally, the Atkinson cycle is controlled so that the intake air amount is reduced by delaying the closing angle of the intake valve and discharging the once sucked air. However, the intake amount can also be controlled by increasing the closing angle of the intake valve. it can. In view of this point, in the present invention, the closing timing of the intake valve is corrected, that is, the closing timing is delayed to be delayed closing Atkinson, or the advanced timing is advanced to close Atkinson. In combination with this, it is possible to realize an internal combustion engine with low fuel consumption and high output.

Further, the gear ratio of C VT120 based on (the characteristics of the gear ratio selection control unit 122a2 in FIG. 10 (b)) characteristic of the output of the engine 10 that will be set for the engine speed NE (torque) a (gear ratio) In addition , when the alcohol fuel is injected from the second injector 32, the engine speed NE is reduced with respect to the output that can be generated by the alcohol fuel injection based on the output characteristics of the engine 10. The maximum gear ratio for low rotation can be increased and a high gear (small gear ratio) can be achieved, or the final gear ratio (final reduction gear ratio) can be adjusted. Therefore, it is possible to use a high gear as a whole, and as shown in FIG. Therefore, a higher gear (smaller gear ratio) can be selected, and the fuel efficiency can be further improved.

  An output determining means for determining whether or not the output of the internal combustion engine can reach a target output when the closing timing of the intake valve 20 is corrected by the intake valve closing timing correcting means (ECU 54, S22); If the output determination means does not determine that the output can reach the target output, it is determined whether the alcohol concentration can be increased. If it is determined that the increase is possible, the alcohol concentration increase means (ECU 54) increases the alcohol concentration. , S26 to S30), in addition to the above-described effects, as long as it is determined that the alcohol concentration can be increased, the output of the engine 10 can reach the target output.

  The first injector includes an injector 30 that directly injects the various fuels into the combustion chamber 22, and the second injector includes an injector 32 that injects the alcohol into the intake port 16 in front of the combustion chamber 22. In addition to the effects described above, the first injector 30 is an injector that directly injects various fuels mainly composed of gasoline into the combustion chamber, so that abnormal combustion can be avoided by the latent heat of gasoline of the injected various fuels. In addition, since the second injector 32 is an injector that injects alcohol into the intake port 16a, the accuracy and cost of components such as a pressure pump can be reduced, and the configuration can be simplified.

  In FIG. 12, in the case of a high gear, it is desirable to maintain acceleration performance at a value, for example, about 20% higher than the same load (same BMEP).

  In the above description, the main fuel tank 34 stores various fuels including alcohol fuel, and the sub fuel tank 44 stores alcohol fuel. However, the main fuel tank 34 stores gasoline fuel and the sub fuel tank 44 stores alcohol fuel. You may do it.

  In the above description, the CVT is described as a transmission, more specifically, an automatic transmission. However, when calculating the torque from the engine speed in the control of FIG. 10, the characteristics of FIG. If it is configured to select a large minimum gear ratio, it can be applied to a stepped automatic transmission.

  DESCRIPTION OF SYMBOLS 10 Internal combustion engine (engine), 14 Throttle valve, 20 Intake valve, 22 Combustion chamber, 26 DBW mechanism, 30 1st (direct injection) injector, 32 2nd (port) injector, 34 Main fuel tank, 42 Gas-liquid separator 44 Sub fuel tank, 54 ECU (electronic control unit), 56 Spark plug (ignition means), 60 Ignition device (ignition means), 80 VTC (Valve valve opening timing variable mechanism), 82 Crank angle sensor, 84 Air flow meter, 86 MAP sensor, 90 throttle opening sensor, 96 A / F sensor, 100 alcohol sensor, 102 level sensor, 104 accelerator opening sensor, 120 CVT (transmission), 122 second ECU

Claims (3)

A valve opening / closing timing variable mechanism capable of changing the opening / closing timing of the intake valve, ignition means, a first injector capable of injecting various fuels mainly composed of gasoline, and alcohol fuel having an octane number higher than that of the various fuels can be injected. An air-fuel mixture produced by mixing the fuel injected from at least one of the first and second injectors with the intake air, compressed by a piston in a combustion chamber, and ignited and burned by the ignition means. In the on-vehicle internal combustion engine control apparatus that drives the drive wheels by shifting with a transmission, the alcohol concentration detection means for detecting the alcohol concentration of the various fuels, and at least the engine speed and the engine output torque Knocking determination means for determining whether or not the probability of occurrence of knocking is equal to or greater than a threshold value; A target compression ratio calculating means for calculating a target compression ratio based on the detected alcohol concentration, and the valve opening / closing timing so as to be the calculated target compression ratio an intake valve closing timing correction means for correcting the closing timing of the intake valve by operating the variable mechanism controls the transmission ratio of the pre-Symbol transmission based on the output characteristics that will be set for the engine speed A gear ratio such that when the alcohol fuel is injected from the second injector, the engine speed decreases with respect to the output that can be generated by injecting the alcohol fuel, based on the characteristics of the output. A control device for an on-vehicle internal combustion engine, comprising: a transmission ratio control means for selecting   When the intake valve closing timing is corrected by the intake valve closing timing correcting means, output determining means for determining whether or not the output of the internal combustion engine can reach a target output, and the output determining means outputs the output by the output determining means. An alcohol concentration increasing means for determining whether or not the alcohol concentration can be increased when it is not determined that the target output can be reached, and for increasing the alcohol concentration when it is determined that the target output can be increased. Item 2. A control device for an on-vehicle internal combustion engine according to Item 1.   2. The first injector includes an injector that directly injects the various fuels into the combustion chamber, and the second injector includes an injector that injects the alcohol into an intake port in front of the combustion chamber. Or the control apparatus of the vehicle-mounted internal combustion engine of 2.

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