JP2014202154A - Control device for spark ignition type engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the afterburning of vaporized fuel derived from alcohol-containing fuel and supplied from an oil pan, which may be caused in a spark ignition type engine to which the alcohol-containing fuel is supplied, during executing deceleration fuel cutoff.SOLUTION: A PCM 50 estimates the amount of vaporized fuel vaporized and gasified from engine oil along with temperature rise and flowing into a combustion chamber, after mixed into the engine oil in the oil pan, as it is unburnt, of fuel injected from an injector 11, and prohibits deceleration fuel cutoff control which cuts off fuel supply to the engine and spark ignition during the travel of a vehicle when an equivalent ratio found from the estimated amount of the vaporized fuel is equal to or greater than a threshold value set from a view point of whether the afterburning of the vaporized fuel is caused or not in an exhaust passage from an exhaust port to a catalyst device, even if deceleration fuel cutoff conditions are established.

Description

  The present invention relates to a control device for a spark ignition engine to which alcohol, gasoline, or a mixed fuel thereof is supplied as fuel.

  In recent years, from the viewpoint of improving environmental problems such as global warming, the use of so-called biomass ethanol purified from plant resources (for example, sugarcane and corn) as fuel for vehicle engines has been devised and put into practical use.

  Biomass ethanol is often used in a mixed state with gasoline. For example, a fuel called E25 in which 25% ethanol is mixed with gasoline and a fuel called E95 in which ethanol is 95% (the rest is water) are sold. However, since the user who uses the vehicle determines which fuel to supply depending on the price at that time, the fuel in the fuel tank of the vehicle is a mixture of E25 and E95 at an arbitrary ratio. For this reason, the concentration of ethanol in the fuel fluctuates every time fueling, and can take any value from 25% to 95%.

  Therefore, in a vehicle using an ethanol-containing fuel, the ethanol concentration of the fuel is estimated or detected using an alcohol sensor as disclosed in Patent Documents 1 and 2 so that the ethanol concentration can be changed. An engine having a function of changing the fuel injection amount in accordance with the acquired ethanol concentration is mounted. A vehicle that can use a fuel having an arbitrary ethanol concentration (generally an alcohol concentration) in this way is called a flex fuel vehicle (FFV).

JP 05-60003 A JP 2010-133288 A

  By the way, in the fuel containing alcohol like ethanol, compared with fuel (E0) of 100% of gasoline, there exists a problem that the vaporization performance of fuel deteriorates, so that alcohol concentration is high. The reason for this is that gasoline is a mixture of multiple components with different molecular formulas, so some of them can evaporate and vaporize even at relatively low temperatures due to the presence of low-boiling components, whereas alcohol is a single component defined by a single molecular formula. Therefore, it is hardly evaporated / vaporized below the boiling point (78.3 ° C. in ethanol). Due to the nature of the alcohol-containing fuel, the following problems may occur during execution of so-called deceleration fuel cut control in FFV.

  That is, when the engine is cold such as immediately after the engine is started, unburned fuel is generated because the fuel is not sufficiently vaporized, and the generated unburned fuel leaks into the crankcase from the gap between the cylinder and the piston, and the engine in the oil pan Mix in oil. The mixed fuel evaporates and vaporizes from the engine oil as the engine warms up, returns to the intake passage through a PCV (positive crankcase ventilation) hose that communicates the crankcase and the intake passage, and reaches the combustion chamber. . Here, alcohol vaporizes rapidly as the temperature approaches the boiling point, and the amount of evaporation increases, so the time when the amount of alcohol evaporation increases rapidly (that is, the temperature of the engine oil in the oil pan is the boiling point of the alcohol). When the oil approaches, a large amount of alcohol evaporates and vaporizes from the oil pan, and this large amount of evaporated and vaporized alcohol flows into the combustion chamber.

  On the other hand, the deceleration fuel cut control is a control for cutting off the fuel supply to the engine in order to improve fuel consumption when a predetermined fuel cut condition (for example, the vehicle speed is equal to or higher than a predetermined vehicle speed) is satisfied when the vehicle decelerates. It is. During the execution of the deceleration fuel cut control, fuel injection from the injector and spark ignition by the spark plug are stopped. When the engine speed decreases to a predetermined return speed as the vehicle speed decreases due to fuel cut, fuel supply from the injector and ignition / combustion by the spark plug are resumed in order to avoid engine stall (fuel) return).

  Therefore, if the time when a large amount of alcohol derived from the alcohol-containing fuel evaporated and vaporized from the oil pan flows into the combustion chamber overlaps with the time when spark ignition is stopped by the deceleration fuel cut control, the alcohol flowing into the combustion chamber is reduced. Most of the vaporized fuel as a main component, that is, the vaporized fuel derived from the alcohol-containing fuel from the oil pan, is discharged into the exhaust passage without being burned in the combustion chamber. Then, the vaporized fuel discharged into the exhaust passage receives heat by touching a metal exhaust manifold or a case of the catalyst device that has been heated to a high temperature, and burns afterward in the exhaust passage. As a result, the catalyst device may be heated excessively, causing a problem that the carrier cracks or the carrier melts.

  The present invention has been made in view of the above circumstances, and in a spark ignition engine to which an alcohol-containing fuel is supplied, vaporization derived from the alcohol-containing fuel from an oil pan during execution of deceleration fuel cut control. An object of the present invention is to provide a control device for a spark ignition engine capable of avoiding afterburning of fuel.

  In order to solve the above problems, the present invention includes an injector for injecting fuel into a cylinder and an ignition plug for igniting the injected fuel. As the fuel, alcohol, gasoline, or a mixed fuel thereof is used. A controller for a spark ignition engine to be supplied, which is unburned in the fuel injected from the injector and mixed into the engine oil in the oil pan, and then evaporated and vaporized from the engine oil as the temperature rises. An estimation means for estimating the amount of vaporized fuel flowing into the combustion chamber, and a deceleration for performing a deceleration fuel cut control that cuts off the fuel supply and spark ignition to the engine when a predetermined fuel cut condition is satisfied when the vehicle decelerates. The equivalence ratio obtained from the fuel cut means and the amount of vaporized fuel estimated by the estimation means is the exhaust gas from the exhaust port to the catalyst device. A deceleration fuel cut prohibiting means for prohibiting the deceleration fuel cut control even when the fuel cut condition is satisfied when the vaporized fuel is equal to or greater than a threshold set in view of whether or not the vaporized fuel burns afterward in the road; A control device for a spark ignition engine characterized by comprising the above.

  According to the present invention, in a spark ignition engine supplied with an alcohol-containing fuel, an equivalent ratio (referred to as a predicted equivalent ratio) obtained from an estimated amount of vaporized fuel derived from the alcohol-containing fuel from the oil pan that flows into the combustion chamber. However, when the vaporized fuel is equal to or higher than a threshold set in view of whether or not the vaporized fuel is burnt in the exhaust passage, the vaporized fuel is likely to burn after in the exhaust passage. Even if the fuel cut condition is satisfied, the deceleration fuel cut control is prohibited. As a result, the fuel supply to the engine and the spark ignition are continued without being stopped, so that the vaporized fuel whose main component is alcohol flowing into the combustion chamber burns in the combustion chamber. Therefore, the afterburning of the vaporized fuel in the exhaust passage is avoided before the deceleration fuel cut control is started. As a result, overheating of the catalyst device, and hence damage to the carrier, can be prevented.

  As described above, according to the present invention, there is provided a control device for a spark ignition engine capable of avoiding afterburning of vaporized fuel derived from alcohol-containing fuel from an oil pan during execution of deceleration fuel cut control.

  In the present invention, preferably, when the deceleration fuel cut control is executed, detection means for detecting that combustion is occurring, and when the detection means detects that combustion is occurring, the deceleration fuel cut is performed. A deceleration fuel cut stopping means for stopping the deceleration fuel cut control being executed is further provided even when the control is being executed (Claim 2).

  According to this configuration, when it is detected that combustion is occurring despite the execution of the deceleration fuel cut control, it is considered that the vaporized fuel is actually afterburning in the exhaust passage. . Therefore, even if the deceleration fuel cut control is being executed, when combustion is detected, the deceleration fuel cut control being executed is stopped. As a result, the fuel supply to the engine and spark ignition are resumed without waiting for a predetermined fuel return condition (for example, the engine speed to fall to a predetermined return speed). The vaporized fuel containing as a main component begins to burn quickly in the combustion chamber. Therefore, afterburning of the vaporized fuel in the exhaust passage is avoided after the start of the deceleration fuel cut control. As a result, overheating of the catalyst device, and hence damage to the carrier is further prevented.

  In the present invention, preferably, when the deceleration fuel cut control is prohibited or when the deceleration fuel cut control is stopped, a running resistance increasing means for increasing the running resistance of the vehicle during the deceleration fuel cut control that should be originally performed is provided. (Claim 3).

  As described above, in order to avoid the vaporization fuel derived from the alcohol-containing fuel from being burned after execution of the deceleration fuel cut control, if the deceleration fuel cut control is prohibited or stopped in the middle, Even when the vehicle is decelerating, there is a possibility that a braking feeling (called an emblem feeling) due to engine braking cannot be obtained. Therefore, according to this configuration, when the deceleration fuel cut control is prohibited or stopped, the running resistance of the vehicle is increased during the period of the deceleration fuel cut control that should be performed, so that the above-described problems can be avoided. And an appropriate emblem feeling is imparted.

  In the present invention, it is preferable that the running resistance increasing means slips a brake element in the transmission that is opened when the deceleration fuel cut control is executed.

  According to this configuration, the braking force acts on the torque transmission in the transmission between the wheel and the engine, so that the running resistance of the vehicle is reliably increased when the deceleration fuel cut control is prohibited or stopped. To do.

  In the present invention, it is preferable that the running resistance increasing means generates power from an alternator driven by the output shaft of the engine.

  According to this configuration, when the load for generating the alternator is applied to the output shaft of the engine, the running resistance of the vehicle surely increases when the deceleration fuel cut control is prohibited or stopped.

  In the spark ignition engine to which the alcohol-containing fuel is supplied, the present invention can avoid the afterburning of the vaporized fuel derived from the alcohol-containing fuel from the oil pan during the execution of the deceleration fuel cut control. This contributes to the development and improvement of FFV technology that can be used as fuel.

1 is an overall configuration diagram of a spark ignition engine mounted on an FFV according to an embodiment of the present invention. It is a skeleton diagram showing a configuration of an automatic transmission connected to the engine. It is a fastening table | surface which shows the relationship between the friction element of the said automatic transmission, and a gear stage. It is a control system figure of the above-mentioned engine. It is a conceptual diagram of the shift map of the said automatic transmission. It is a graph which shows the relationship between temperature and ethanol vapor pressure. It is a time chart which shows change of various parameters of deceleration fuel cut control which PCM of the above-mentioned engine performs. It is a flowchart of the said deceleration fuel cut control.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Engine configuration As shown in FIG. 1, a spark ignition engine 1 according to this embodiment is a four-cycle engine having a plurality of cylinders 2 (only one is shown in FIG. 1). A cylinder block 4 that rotatably supports a crankshaft 3, a cylinder head 5 disposed above the cylinder block 4, an oil pan 6 disposed below the cylinder block 4, and a cylinder head 5. The outer shape of the engine main body is substantially formed by the head cover 7 thus formed.

  A piston 9 connected to the crankshaft 3 via a connecting rod 8 is slidably accommodated in each cylinder 2, and a combustion chamber 10 is formed above the piston 9. An injector 11 that directly injects fuel into the combustion chamber 10 is provided in the cylinder head 5, and an ignition plug 12 on the ceiling wall of the combustion chamber 10, an intake valve 14 for opening and closing the intake port 13, and an exhaust port 15 are opened and closed An exhaust valve 16 is provided. The intake valve 14 and the exhaust valve 16 are driven to open and close in conjunction with the crankshaft 3 by valve mechanisms 17 and 18 each having a camshaft (not shown).

  An intake passage 20 is connected to the intake port 13, and an exhaust passage 30 is connected to the exhaust port 15. The intake passage 20 is provided with a throttle valve 21 for adjusting the amount of intake air, and the exhaust passage 30 is provided with a catalyst device 31 for accommodating an unillustrated three-way catalyst for purifying exhaust gas.

  Leaked from the combustion chamber 10 into the crankcase between the crankcase, which is the portion of the engine body that covers the space over the lower part of the cylinder block 4 and the upper part of the oil pan 6, and the intake passage 20 downstream of the throttle valve 21. A PCV (positive crankcase ventilation) hose 23 for recirculating unburned air-fuel mixture (blow-by gas) to the intake passage 20 is provided. Another ventilation hose 24 for ventilation is provided between the head cover 7 and the intake passage 20 upstream of the throttle valve 21.

  The engine 1 includes an alternator 25 that is driven by the crankshaft 3 to generate electric power.

  The engine 1 according to the present embodiment is an engine that can use a fuel containing ethanol. That is, the vehicle according to the present embodiment is an FFV (flex fuel vehicle). Therefore, the fuel tank 40 is supplied with an ethanol-containing fuel such as E95 (ethanol 95% + water 5% fuel) or E25 (ethanol 25% + gasoline 75% fuel). At the time of refueling, E95 or E25 is poured into the fuel tank 40 by an arbitrary amount. Therefore, the ethanol concentration of the fuel in the fuel tank 40 can take various values at that time. The ethanol-containing fuel in the fuel tank 40 is supplied to the injector 11 through the fuel supply pipe 41 and is directly injected from the injector 11 into the combustion chamber 10.

  In the engine 1 according to the present embodiment, since the fuel is directly injected into the combustion chamber 10, the pressure of the fuel supplied to the injector 11 is set to a relatively high pressure. Therefore, atomization of the fuel injected from the injector 11 is promoted.

  In the engine 1 according to the present embodiment, the geometric compression ratio and the effective compression ratio are set to a relatively high compression ratio (for example, the geometric compression ratio is 12.5 or more which is a higher value for a gasoline engine). 20 or less). Therefore, for example, when the fuel is directly injected into the combustion chamber 10 in the latter half of the compression stroke at the time of starting the engine 1, the injected fuel is promoted to vaporize in the high-temperature combustion chamber 10, and rich around the spark plug 12. An air-fuel mixture is generated (weak stratification), and the ignition stability is improved in combination with the atomization of fuel.

  By the way, gasoline is a mixture of a plurality of components having different molecular formulas, whereas alcohol is a single component defined by one molecular formula. For this reason, gasoline can partly evaporate and vaporize even at relatively low temperatures due to the presence of low-boiling components, but alcohol can be ignited and combusted at temperatures below the boiling point (78.3 ° C for ethanol). This makes it difficult to start the engine.

  In order to cope with this problem, conventionally, a sub-tank dedicated to E25 having a low alcohol concentration or a sub-tank dedicated to gasoline, a supply pipe, a fuel rail, and a sub-injector have been provided exclusively for starting the engine. An engine is started using a fuel system (sub tank system). However, if a sub fuel system is provided in addition to the main fuel system (the fuel tank 40, the fuel supply pipe 41, the injector 11, etc.), the hardware is complicated, the cost is increased, and the vehicle weight is increased. . There are also problems to be solved in terms of safety, such as the location of the sub tank.

  Therefore, in the engine 1 according to the present embodiment, instead of providing a sub-tank system dedicated to starting the engine, as described above, the fuel droplets injected from the injector 11 into the combustion chamber 10 are atomized and the compression ratio is reduced. Is increased to increase the temperature of the combustion chamber 10 when the piston 9 is raised, and the fuel is injected into the combustion chamber 10 in the latter half of the compression stroke. Even during the intermediate start, the amount of evaporation / vaporization in the combustion chamber 10 is increased to ensure the startability of the engine 1 (sub tankless system).

(2) Configuration of Automatic Transmission FIG. 2 is a skeleton diagram showing the configuration of the automatic transmission 60 connected to the engine 1. The automatic transmission 60 includes, as main components, a torque converter 61 connected to the crankshaft 3 and a transmission mechanism 63 to which output rotation of the torque converter 61 is input via an input shaft 62. The transmission mechanism 63 is housed in the transmission case 64 in a state of being disposed on the axis of the input shaft 62.

  The output rotation of the speed change mechanism 63 is transmitted to the differential device 67 via the counter drive mechanism 66 from the output gear 65 disposed in the intermediate portion of the input shaft 62 on the axis of the input shaft 62, and the left and right axles 67a, 67b is driven.

  The torque converter 61 includes a case 61a connected to the crankshaft 3, a pump 61b fixed in the case 61a, and a turbine 61c disposed opposite to the pump 61b and driven by hydraulic oil by the pump 61b. A stator 61e interposed between the pump 61b and the turbine 61c and supported by the transmission case 64 via a one-way clutch 61d to increase torque, and the case 61a and the turbine 61c. The lockup clutch 61f is provided between the crankshaft 3 and the turbine 61c via the case 61a. Then, the rotation of the turbine 61 c is transmitted to the transmission mechanism 63 via the input shaft 62.

  The transmission mechanism 63 includes first, second, and third planetary gear sets 70, 80, and 90, which are arranged in this order from the torque converter side on the anti-torque converter side of the output gear 65 in the transmission case 64. Has been.

  The first clutch 100 and the second clutch 110 are arranged on the torque converter side of the output gear 65 as friction elements constituting the transmission mechanism 63, and the first brake 120, The second brake 130 and the third brake 140 are arranged in this order from the torque converter side.

  The first, second, and third planetary gear sets 70, 80, 90 are all single-pinion type planetary gear sets. Each gear set 70, 80, 90 has sun gears 71, 81, 91, pinions 72, 82, 92 that mesh with these sun gears 71, 81, 91, and a carrier 73 that supports these pinions 72, 82, 92. 83, 93 and ring gears 74, 84, 94 meshing with the pinions 72, 82, 92.

  The input shaft 62 is connected to the sun gear 91 of the third planetary gear set 90. The sun gear 71 of the first planetary gear set 70 and the sun gear 81 of the second planetary gear set 80 are connected, the ring gear 74 of the first planetary gear set 70 and the carrier 83 of the second planetary gear set 80 are connected, and the second planetary gear set 80 The ring gear 84 and the carrier 93 of the third planetary gear set 90 are connected. An output gear 65 is connected to the carrier 73 of the first planetary gear set 70.

  A sun gear 71 of the first planetary gear set 70 and a sun gear 81 of the second planetary gear set 80 are connected to the input shaft 62 via the first clutch 100 so as to be connectable and detachable. The carrier 83 of the second planetary gear set 80 is connected to the input shaft 62 via the second clutch 110 so as to be connected and disconnected.

  The ring gear 74 of the first planetary gear set 70 and the carrier 83 of the second planetary gear set 80 are connected to the transmission case 64 via the first brake 120 so as to be connectable and detachable. The ring gear 84 of the second planetary gear set 80 and the carrier 93 of the third planetary gear set 90 are connected to the transmission case 64 via the second brake 130 so as to be connectable and detachable. The ring gear 94 of the third planetary gear set 90 is connected to the transmission case 64 via the third brake 140 so as to be connectable and detachable.

  With the above-described configuration, according to the speed change mechanism 63, as shown in the engagement table of FIG. 3, each friction of the first and second clutches 100 and 110 and the first, second, and third brakes 120, 130, and 140 A forward 1st to 6th speed and a reverse speed are achieved by a combination of the fastening states of the elements.

(3) Control System As shown in FIG. 4, the vehicle (FFV) according to the present embodiment includes a PCM (powertrain control module) 50. As is well known, the PCM 50 is a microprocessor including a CPU, a ROM, a RAM, and the like, and corresponds to the estimating means, the deceleration fuel cut prohibiting means, the deceleration fuel cut prohibiting means, and the deceleration fuel cut stopping means of the present invention.

  The PCM 50 is provided in the intake passage 20 and detects an air flow sensor SW1 for detecting the intake air amount, an engine speed sensor SW2 for detecting the engine speed, and an engine water temperature (temperature of engine cooling water). Engine water temperature sensor SW3, linear air-fuel ratio sensor (oxygen concentration sensor) SW4 provided in the exhaust passage 30 for detecting the oxygen concentration in the exhaust gas, presence / absence of accelerator operation (depressing the accelerator pedal) by the driver, and accelerator An accelerator position sensor SW5 for detecting an operation amount (depressing amount of an accelerator pedal) and a vehicle speed sensor SW6 for detecting a traveling speed of the vehicle are electrically connected to each other.

  The PCM 50 controls the engine 1 and the automatic transmission 60 based on various information input from the various sensors SW1 to SW6. In particular, the PCM 50 performs air-fuel ratio feedback control using the linear air-fuel ratio sensor SW4 so that the engine 1 is operated at the stoichiometric air-fuel ratio in order to improve the exhaust gas purification rate of the catalyst device 31. Further, the PCM 50 performs ethanol concentration estimation control for estimating the ethanol concentration of the fuel in the fuel tank 40 by using the linear air-fuel ratio sensor SW4, for example, without using an alcohol sensor or the like. Further, the PCM 50 performs vaporized fuel amount estimation control for estimating the amount of vaporized fuel derived from the ethanol-containing fuel from the oil pan 6 (see the next “(4) location of problem”). The PCM 50 performs post-burn detection control for detecting that the vaporized fuel is actually post-burning in the exhaust passage 30. Further, the PCM 50 performs a deceleration fuel cut control that cuts off the fuel supply and spark ignition to the engine 1 in order to improve fuel efficiency and the like when a predetermined fuel cut condition is satisfied during vehicle deceleration.

  In order to execute these various controls, the PCM 50 performs the injector 11, the spark plug 12, the throttle valve actuator 22 for driving the throttle valve 21, the alternator 25, and the automatic transmission 60 (more specifically, the friction elements 100 and 110). , 120, 130, 140 are electrically connected to each other and a solenoid valve for controlling the supply and discharge of hydraulic pressure for fastening or releasing, and outputs control signals to these various devices.

  For example, the PCM 50 determines the shift speed from the vehicle speed and the throttle opening (the opening of the throttle valve 21) based on the shift map conceptually shown in FIG. 5 so that the determined shift speed is realized. The friction elements 100, 110, 120, 130, 140 are fastened or released according to the fastening table.

  In FIG. 5, the shift line when the shift stage is shifted up is indicated by a solid line, and the shift line when the shift stage is shifted down is indicated by a broken line. FIG. 5 is merely a conceptual diagram, and it goes without saying that the position and shape of each line with respect to the vehicle speed are not limited to this.

  A region where the throttle opening is zero (accelerator opening fully closed) in the medium to high speed region is a deceleration fuel cut region (F / C region) in which the PCM 50 performs deceleration fuel cut control. That is, in this region, the fuel injection from the injector 11 and the spark ignition by the spark plug 12 are not performed and the fuel is stopped.

(4) Location of the problem Generally, when the engine is cold, such as immediately after the engine is started, the fuel is insufficiently vaporized, so that the amount of the fuel injected from the injector 11 remains unburned without being burned. The remaining unburned fuel leaks into the crankcase from the gap between the side wall of the cylinder 2 and the peripheral surface of the piston 9, enters the oil pan 6, and enters the engine oil in the oil pan 6. When the temperature of the engine oil rises as the engine 1 warms up, the fuel mixed in the engine oil evaporates and vaporizes from the engine oil in the crankcase, and passes through the PCV hose 23 and the ventilation hose 24 to the intake passage 20. The air is recirculated and flows into the combustion chamber 10 together with the intake air (fresh air) flowing from the intake upstream side through the intake passage 20.

  Here, as shown in the ethanol vapor pressure characteristics of FIG. 6, as the temperature of the ethanol approaches the boiling point (78.3 ° C.), the vaporization rapidly proceeds and the amount of evaporation increases. Therefore, when the amount of ethanol evaporation increases rapidly (that is, when the temperature of the engine oil in the oil pan 6 approaches the boiling point of ethanol of 78.3 ° C.), a large amount of ethanol evaporates and vaporizes from the oil pan 6. The large amount of evaporated and vaporized ethanol flows into the combustion chamber 10.

  Therefore, if the time when a large amount of ethanol derived from the ethanol-containing fuel evaporated and vaporized from the oil pan 6 flows into the combustion chamber 10 and the timing when the spark ignition is stopped by the deceleration fuel cut control overlap, it flows into the combustion chamber 10. Most of the vaporized fuel mainly composed of ethanol is discharged into the exhaust passage 30 without being burned in the combustion chamber 10. The vaporized fuel discharged to the exhaust passage 30 receives heat by touching a metal exhaust manifold whose temperature is increased to a high temperature, the case of the catalyst device 31, etc., and burns afterward in the exhaust passage 30. As a result, the catalyst device 31 is excessively heated, and there arises a problem that the carrier is cracked or the carrier is melted. As a result, not only the catalyst performance deteriorates, but secondary damage such as damage to the engine 1 due to the fragments of the carrier may occur.

  Therefore, in the present embodiment, measures are taken to avoid the afterburning of the vaporized fuel derived from the ethanol-containing fuel from the oil pan 6 as described above. For this purpose, the PCM 50 is described as follows. Then, vaporized fuel amount estimation control and afterburn detection control are performed.

(5) Content of control [5-1] Ethanol concentration estimation control The ethanol concentration estimation control performed by the PCM 50 is approximately as follows.

  The relationship between the fuel ethanol concentration and the stoichiometric air-fuel ratio is uniquely determined. For example, when the ethanol concentration is 0% (total amount gasoline), the theoretical air-fuel ratio is 14.7, and when the ethanol concentration is 100%, the theoretical air-fuel ratio is 9.0. And the theoretical air fuel ratio of the fuel whose ethanol concentration is a value in the meantime (above 0% to less than 100%) is 1: 1 on a straight line connecting 14.7 and 9.0. This straight line has a slope such that the theoretical air-fuel ratio decreases by 0.057 every time the ethanol concentration increases by 1%.

  For example, suppose that the fuel injection amount that the theoretical air-fuel ratio X realizes is set with the ethanol concentration estimated to be 50%. As a result, if the theoretical air-fuel ratio specified based on the information from the linear air-fuel ratio sensor SW4 is X, it can be determined that the estimated value is correct (the actual ethanol concentration is 50%). However, when the stoichiometric air-fuel ratio specified based on the information from the linear air-fuel ratio sensor SW4 is larger than X, it can be determined that the actual ethanol concentration is lower than 50%, and the linear air-fuel ratio sensor SW4 When the stoichiometric air-fuel ratio specified based on the information from is smaller than X, it can be determined that the actual ethanol concentration is higher than 50% by the smaller amount.

  The PCM 50 obtains the deviation amount of the ethanol concentration by applying the deviation amount of the theoretical air-fuel ratio to the slope of the straight line. Then, the actual ethanol concentration is estimated by adding the deviation amount of the ethanol concentration to the initial estimated value (50% in the above example).

[5-2] Vaporized Fuel Amount Estimation Control The vaporized fuel amount estimation control performed by the PCM 50 is approximately as follows.

  The PCM 50 calculates an unburned fuel amount Q1 mixed in the engine oil in the oil pan 6 when cold (unburned fuel amount calculating step). More specifically, the PCM 50 starts increasing the fuel injection amount to ensure startability at the time of cold start, for example, after the residual fuel amount Q3 remaining in the engine oil in the oil pan 6 has become zero last time. From this point in time, the total amount of unburned fuel that has fallen into the oil pan 6 and has been mixed into the engine oil is calculated. For example, the PCM 50 calculates the amount of unburned fuel mixed in the engine oil at every injection timing, that is, every time fuel is injected through all the cylinders, and integrates the obtained values.

  Further, the PCM 50 calculates a vaporized fuel amount Q2 that is vaporized from the engine oil in the oil pan 6 during warm-up (vaporized fuel amount calculation step). More specifically, the PCM 50, from the time when the amount of unburned fuel mixed in the engine oil started to increase after the residual fuel amount Q3 remaining in the engine oil in the oil pan 6 last reached zero, Calculate the total amount of fuel vaporized and evaporated from engine oil as the temperature rises. For example, the PCM 50 calculates the amount of ethanol vaporized per unit time as the temperature rises from the unburned fuel mixed in the engine oil from the ethanol evaporation rate (evaporation amount per unit time) and the like. Further, the PCM 50 calculates the vaporization amount per unit time associated with the temperature rise of the entire unburned fuel mixed in the engine oil from not only the evaporation rate of ethanol but also the evaporation rate of the whole fuel including gasoline. Then, the PCM 50 multiplies the calculated value of the vaporization amount of the entire fuel per unit time by time (more specifically, the elapsed time from when the amount of unburned fuel mixed in the engine oil starts to increase). Thus, the total amount of vaporized fuel evaporated and vaporized from the engine oil is calculated.

  Further, the PCM 50 calculates a residual fuel amount Q3 remaining in the engine oil in the oil pan 6 at the present time (residual fuel amount calculating step). Specifically, the PCM 50 subtracts the vaporized fuel amount Q2 calculated in the vaporized fuel amount calculation step from the unburned fuel amount Q1 calculated in the unburned fuel amount calculation step, thereby obtaining a residual fuel amount Q3 remaining in the engine oil. Is calculated (Q3 = Q1-Q2). The calculated residual fuel amount Q3 is considered in the unburned fuel amount calculating step and the vaporized fuel amount calculating step as described above.

  Here, as shown in the ethanol vapor pressure characteristic of FIG. 6, the time when the vapor pressure of ethanol suddenly increases (the time when the temperature of the engine oil in the oil pan 6 approaches the boiling point of ethanol of 78.3 ° C.). In the vaporized fuel amount calculating step, the evaporation rate of ethanol is increased, whereby the vaporized amount of ethanol from the oil pan 6 per unit time is calculated to a large value. Further, not only the evaporation rate of ethanol but also the evaporation rate of the whole fuel including gasoline is increased, and the vaporization amount of the entire fuel per unit time from the oil pan 6 is thereby calculated to a large value.

  In the vaporized fuel amount calculating step, the PCM 50 determines the value of the vaporization amount of the entire fuel per unit time calculated from the evaporation rate of the entire fuel in the oil pan 6 while remaining unburned in the fuel injected from the injector 11. The amount of vaporized fuel flowing into the combustion chamber 10 after evaporating and vaporizing from the engine oil as the temperature rises is estimated. That is, this is the estimated amount of vaporized fuel derived from the ethanol-containing fuel from the oil pan 6 used in step S4 of FIG.

[5-3] Afterburn Detection Control The afterburn detection control performed by the PCM 50 is approximately as follows.

  Since the linear air-fuel ratio sensor SW4 detects the oxygen concentration contained in the exhaust gas before being introduced into the catalyst device 31, the PCM 50 specifies the equivalence ratio φ based on the detected value of the linear air-fuel ratio sensor SW4. Whether or not combustion is occurring can be determined from the value of the equivalent ratio φ. For example, when combustion (afterburn) occurs, the richer the air-fuel ratio of the burned mixture (that is, the greater the equivalent ratio φ), the more oxygen is consumed and the oxygen concentration contained in the exhaust gas decreases. Therefore, the PCM 50 can calculate the equivalence ratio φ according to the degree of decrease in the oxygen concentration.

  Accordingly, when it is recognized that combustion is occurring from the value of the equivalence ratio φ even though the deceleration fuel cut control is being performed, the PCM 50 causes the vaporized fuel to actually burn after-burn in the exhaust passage 30. Judge that For example, in the PCM 50, when the equivalence ratio (actual equivalence ratio φb) specified from the detection value of the linear air-fuel ratio sensor SW4 is equal to or larger than a predetermined threshold β (see step S6 in FIG. 8), the post-burning occurs. Judge.

  The threshold β is a value set from the viewpoint of whether or not the vaporized fuel is actually afterburning in the exhaust passage 30 from the exhaust port 15 to the catalyst device 31, and is, for example, 0.3 or less. Etc. For such a threshold value β, a large number of values are experimentally obtained in advance according to changes in a plurality of parameters using an actual machine, mapped, and stored in the memory of the PCM 50.

  From the above, in the present embodiment, the linear air-fuel ratio sensor SW4 corresponds to the detection means of the present invention (means for detecting that combustion is occurring during execution of the deceleration fuel cut control).

[5-4] Deceleration Fuel Cut Control Next, deceleration fuel cut control performed by the PCM 50 will be described.

  FIG. 7 is a time chart showing changes in various parameters of the deceleration fuel cut control. In the figure, time t1 is the time when the vehicle is traveling, for example, when the accelerator opening is fully closed and deceleration is started in a state where the vehicle speed is equal to or higher than the predetermined vehicle speed, and time t2 is the time until the engine speed reaches the predetermined return speed. The time to decrease, time t3, is the time when the vehicle stops (the vehicle speed becomes zero).

  When deceleration starts at time t1, the fuel cut flag (F / C flag) is set from off to on. Thereby, the fuel injection from the injector 11 and the spark ignition by the spark plug 12 are stopped, and the fuel efficiency is improved. That is, it is a deceleration fuel cut. When the engine speed decreases to the return speed at time t2 as the vehicle speed decreases due to deceleration fuel cut, the fuel cut flag (F / C flag) is reset from on to off. Thereby, fuel injection from the injector 11 and spark ignition by the spark plug 12 are restarted, and engine stall is avoided. That is, the fuel return from the deceleration fuel cut.

  The charging efficiency Ce of the cylinder 2 decreases to a substantially minimum value between times t1 and t2. This is because the throttle valve 21 is closed to a fully closed state with substantially zero opening during the deceleration fuel cut because the accelerator opening is fully closed. Then, at the time of fuel recovery after time t2, the throttle valve 21 is opened by a predetermined amount, and an amount of intake air corresponding to the combustion injection amount is introduced into the cylinder 2. As a result, the charging efficiency Ce of the cylinder 2 increases by a predetermined amount after the time t2.

  In addition, after time t3 when the vehicle stops, the charging efficiency Ce is fixed to the charging efficiency during idling.

  In such deceleration fuel cut control, the PCM 50 has an equivalent ratio (predicted equivalent ratio φa) calculated from the estimated amount of vaporized fuel estimated by the vaporized fuel amount estimation control and the intake flow rate equal to or greater than a predetermined threshold value α. In some cases (see step S4 in FIG. 8), even if the fuel cut condition (the vehicle speed is equal to or higher than the predetermined vehicle speed, etc.) is satisfied at time t1, the deceleration fuel cut control is not executed and is prohibited.

  That is, if the time when a large amount of alcohol derived from the alcohol-containing fuel evaporated and vaporized from the oil pan 6 flows into the combustion chamber 10 and the time when spark ignition is stopped by the deceleration fuel cut control, the flow into the combustion chamber 10 occurs. Most of the vaporized fuel mainly composed of alcohol is discharged into the exhaust passage 30 without burning in the combustion chamber 10. The vaporized fuel discharged to the exhaust passage 30 receives heat by touching a metal exhaust manifold whose temperature is increased to a high temperature, the case of the catalyst device 31, etc., and burns afterward in the exhaust passage 30. As a result, the catalyst device 31 is excessively heated, and there arises a problem that the carrier is cracked or the carrier is melted.

  In order to avoid such a vaporized fuel derived from the ethanol-containing fuel from the oil pan 6 from being burned after, the PCM 50 calculates an estimated amount of the vaporized fuel amount in the vaporized fuel amount estimation control, and calculates the estimated The predicted equivalent ratio φa is further calculated from the amount and the intake flow rate. As a result, the afterburning of the vaporized fuel in the exhaust passage 30 is avoided before the start of the deceleration fuel cut control, and the catalyst device 31 is prevented from being overheated and consequently damaged in the carrier.

  The threshold value α is a value set from the viewpoint of whether the vaporized fuel is burnt afterward in the exhaust passage 30 from the exhaust port 15 to the catalyst device 31, and is a value such as 0.5 or more, for example. It is. For such a threshold value α, a large number of values are experimentally obtained in advance according to changes in a plurality of parameters using an actual machine, mapped, and stored in the memory of the PCM 50.

  Further, the PCM 50 starts the deceleration fuel cut control because the predicted equivalent ratio φa is less than the threshold value α, but the actual equivalent ratio φb is used in the post-burn detection control although the deceleration fuel cut control is being executed. Is equal to or greater than a predetermined threshold value β, and it is determined that the vaporized fuel is actually afterburning in the exhaust passage 30, even if the deceleration fuel cut control is being executed, Stops cutting control.

  As a result, fuel supply and spark ignition to the engine 1 are resumed without waiting for the engine speed to fall to a predetermined return speed, so that the vaporized fuel containing alcohol that has flowed into the combustion chamber 10 as a main component. Begins to burn in the combustion chamber 10 as soon as possible. Therefore, afterburning of the vaporized fuel in the exhaust passage 30 is avoided after the start of the deceleration fuel cut control. As a result, the catalyst device 31 is further prevented from being overheated and, consequently, the carrier is damaged.

  By the way, in order to prevent the vaporized fuel derived from the ethanol-containing fuel from the oil pan 6 from burning after the deceleration fuel cut control is performed, if the deceleration fuel cut control is prohibited or stopped in the middle, FIG. As shown in (i), the engine torque is generated, which may cause a problem that the feeling of emblem cannot be obtained even during deceleration.

  Therefore, when the deceleration fuel cut control is prohibited, the PCM 50 sets the fuel cut flag to on during the period of the deceleration fuel cut control that should be performed as shown in FIG. 7 (ii). The running resistance is turned on during the running period (during the period from when the fuel cut condition is established to when the fuel return condition is established). Specifically, the PCM 50 slips the third brake 140 of the automatic transmission 60 described with reference to FIGS. In the example of FIG. 5, during the execution of the deceleration fuel cut control (time t1 to t2), the gear position is set to the sixth speed. Therefore, in the present embodiment, during the period of the deceleration fuel cut control that should be originally performed, The second clutch 110 and the second brake 130 are engaged, and the other friction elements are released (see FIG. 3). Accordingly, by slipping the released third brake 140, a braking force acts on torque transmission inside the automatic transmission 6 between the wheel and the engine 1. As a result, the running resistance is turned on, and the running resistance of the vehicle is reliably increased during the period of the deceleration fuel cut control that should be performed (while the fuel cut flag is set to on). The loss of feeling is compensated.

  However, the present invention is not limited to this. For example, when deceleration fuel cut control is executed even at the fifth speed, the second brake 130 released at the fifth speed may be slipped when the shift speed is the fifth speed.

  Alternatively, the PCM 50 generates electric power by driving the alternator 25 with the crankshaft 3 of the engine 1 in order to turn on the running resistance. As a result, a load for generating the alternator 25 is applied to the crankshaft 3, so that the running resistance is turned on, and the running resistance of the vehicle is reliably increased during the deceleration fuel cut control that should be performed. This loss of emblem is compensated.

  Similarly, when the deceleration fuel cut control is stopped, the PCM 50 sets the fuel cut flag to on during the period of the deceleration fuel cut control that should be originally performed, as indicated by reference numeral (iii) in FIG. During this period, the running resistance is turned on during the period from the time when it is determined that the vaporized fuel is actually afterburning in the exhaust passage 30 to the time when the fuel return condition is satisfied. Specifically, the PCM 50 slips the third brake 140 and the second brake 130 of the automatic transmission 60 described with reference to FIGS. Alternatively, the PCM 50 drives the alternator 25 with the crankshaft 3 of the engine 1 to generate power.

  From the above, in this embodiment, the automatic transmission 60 and the alternator 25 should be performed originally when the running resistance increasing means of the present invention (when deceleration fuel cut control is prohibited or when deceleration fuel cut control is stopped). This corresponds to a means for increasing the running resistance of the vehicle during the deceleration fuel cut control.

  Next, an example of specific operation of the deceleration fuel cut control will be described according to the flowchart of FIG.

  When the deceleration fuel cut control (F / C control) starts, the PCM 50 reads various sensor values in step S1, and then determines whether or not the deceleration fuel cut region (F / C region) in step S2 ( When NO, the process returns. When YES (time t1 in FIG. 7), in step S3, from the intake air flow rate and the estimated amount of vaporized fuel derived from the ethanol-containing fuel from the oil pan 6, The predicted equivalent ratio φa is calculated.

  Next, in step S4, the PCM 50 determines whether or not the predicted equivalent ratio φa is equal to or greater than the threshold value α (φa ≧ α). If NO, the process proceeds to step S5, and if YES, the process proceeds to step S8.

  In step S5, the PCM 50 permits a deceleration fuel cut (F / C). That is, fuel injection from the injector 11 and spark ignition by the spark plug 12 are stopped (execution of deceleration fuel cut control).

  On the other hand, in step S8, the PCM 50 prohibits deceleration fuel cut (F / C). That is, the fuel injection from the injector 11 and the spark ignition by the spark plug 12 are continued without stopping.

  After step S5, the PCM 50 determines in step S6 whether or not the actual equivalence ratio φb is greater than or equal to the threshold β (φb ≧ β). If NO, the process proceeds to step S7, and if YES, the process proceeds to step S9.

  In step S7, the PCM 50 continues the deceleration fuel cut (F / C) and returns. That is, when the fuel injection from the injector 11 and the spark ignition by the spark plug 12 continue to be stopped and the engine speed decreases to the return speed (time t2 in FIG. 7), the fuel injection from the injector 11 and the spark plug 12 The spark ignition due to is resumed (fuel return from deceleration fuel cut).

  On the other hand, in step S9, the PCM 50 performs fuel return. In other words, the deceleration fuel cut control being executed is stopped, and the fuel injection from the injector 11 and the spark ignition by the spark plug 12 are resumed without waiting for the engine speed to decrease to the return speed.

  After step S8 and step S9, the PCM 50 increases the running resistance (on) by controlling the automatic transmission 60 and the alternator 25 in step S10, and then returns.

(6) Operation, etc. As described above, in this embodiment, the injector 11 for injecting fuel into the cylinder 2 and the spark plug 12 for igniting the injected fuel are provided. As the fuel, alcohol, gasoline, or these In the spark ignition engine 1 to which the mixed fuel is supplied, the following characteristic configuration is adopted.

  That is, the PCM 50 performs the deceleration fuel cut control that cuts off the fuel supply to the engine 1 and the spark ignition when the vehicle speed is equal to or higher than a predetermined vehicle speed during vehicle deceleration. The PCM 50 mixes the fuel injected from the injector 11 with the unburned engine oil in the oil pan 6, and then evaporates and vaporizes from the engine oil as the temperature rises and flows into the combustion chamber 10. (Evaporated fuel amount estimation control), and whether or not the predicted equivalent ratio φa obtained from the estimated amount of vaporized fuel is post-burned in the exhaust passage 30 from the exhaust port 15 to the catalyst device 31 is determined. If the vehicle speed is greater than or equal to the threshold value α set in view of the above (YES in step S4), even if the vehicle speed is greater than or equal to a predetermined vehicle speed, the deceleration fuel cut control is not performed (step S8). .

  According to this configuration, in the spark ignition engine 1 to which the ethanol-containing fuel is supplied, the predicted equivalent ratio φa obtained from the estimated amount of vaporized fuel derived from the alcohol-containing fuel from the oil pan 6 flowing into the combustion chamber 10 is When the vaporized fuel is greater than or equal to the threshold value α set in view of whether or not the vaporized fuel is burnt in the exhaust passage 30, the vaporized fuel is likely to burn after in the exhaust passage 30. Therefore, even when the vehicle is decelerating, the deceleration fuel cut control is prohibited even if the vehicle speed is equal to or higher than the predetermined vehicle speed. As a result, the fuel supply to the engine 1 and the spark ignition are continued without being stopped, so that the vaporized fuel mainly containing alcohol flowing into the combustion chamber 10 burns in the combustion chamber 10. Therefore, afterburning of the vaporized fuel in the exhaust passage 30 is avoided before the deceleration fuel cut control is started. As a result, overheating of the catalyst device 31 and thus damage to the carrier can be prevented.

  As described above, in the present embodiment, the control device for the spark ignition engine 1 that can prevent the vaporized fuel derived from the ethanol-containing fuel from the oil pan 6 from burning after the deceleration fuel cut control is provided.

  In the present embodiment, the PCM 50 further detects that combustion is occurring during the execution of the deceleration fuel cut control (post-burn detection control), and when it is detected that combustion is occurring (step S6). And YES), even if the deceleration fuel cut control is being executed, the deceleration fuel cut control being executed is stopped (step S9).

  According to this configuration, when it is detected that combustion is occurring despite the execution of the deceleration fuel cut control, it is considered that the vaporized fuel is actually afterburning in the exhaust passage 30. It is done. Therefore, even if the deceleration fuel cut control is being executed, when combustion is detected, the deceleration fuel cut control being executed is stopped. As a result, fuel supply and spark ignition to the engine 1 are resumed without waiting for the engine speed to fall to a predetermined return speed, so that the vaporized fuel containing alcohol that has flowed into the combustion chamber 10 as a main component. Begins to burn in the combustion chamber 10 as soon as possible. Therefore, afterburning of the vaporized fuel in the exhaust passage 30 is avoided after the start of the deceleration fuel cut control. As a result, the catalyst device 31 is further prevented from being overheated and, consequently, the carrier is damaged.

  In the present embodiment, the PCM 50 further performs the deceleration fuel cut control period to be originally performed (step S8) when the deceleration fuel cut control is prohibited (step S8) or when the deceleration fuel cut control is stopped (step S9). 7 at times t1 to t2), the running resistance of the vehicle is increased (turned on).

  As described above, during the execution of the deceleration fuel cut control, in order to prevent the vaporized fuel derived from the ethanol-containing fuel from the oil pan 6 from burning after, the deceleration fuel cut control is prohibited in advance or stopped halfway. Due to the generation of engine torque, there may be a problem that the feeling of emblem cannot be obtained even during deceleration. Therefore, according to this configuration, when the deceleration fuel cut control is prohibited or stopped, the running resistance of the vehicle is increased during the period of the deceleration fuel cut control that should be performed, so that the above-described problems can be avoided. And an appropriate emblem feeling is imparted.

  In the present embodiment, the PCM 50 slips the third brake 140 in the automatic transmission 60 that is opened when the deceleration fuel cut control is executed in order to increase (turn on) the running resistance of the vehicle.

  According to this configuration, the braking force acts on the torque transmission in the automatic transmission 60 between the wheel and the engine, so that the running resistance of the vehicle is ensured when the deceleration fuel cut control is prohibited or stopped. To increase.

  In the present embodiment, the PCM 50 generates power by the alternator 25 that is driven by the crankshaft 3 of the engine 1 in order to increase (turn on) the running resistance of the vehicle.

  According to this configuration, when the load for generating the alternator 25 is applied to the crankshaft 3 of the engine 1, the running resistance of the vehicle reliably increases when the deceleration fuel cut control is prohibited or stopped.

  In the above embodiment, instead of estimating the alcohol concentration of the fuel, an alcohol sensor that directly detects the alcohol concentration of the fuel may be used as the concentration acquisition means.

  Further, since the mechanical resistance is large when the engine temperature is relatively low, even if the intake charge amount to the cylinder 2 is increased at the time of fuel return at time t2, a certain degree of emblem can be obtained. Therefore, in order to prevent the waste of increasing the running resistance of the vehicle in such a case, it is preferable that the PCM 50 increases (on) the running resistance of the vehicle when the engine temperature is equal to or higher than a predetermined threshold temperature. This is one aspect.

  Moreover, in the said embodiment, although ethanol was used as alcohol, it is not restricted to this, For example, you may use methanol, butanol, propanol, etc.

1 Spark ignition engine 2 Cylinder 3 Crankshaft (output shaft)
DESCRIPTION OF SYMBOLS 10 Combustion chamber 11 Injector 12 Spark plug 25 Alternator (running resistance increasing means)
30 exhaust passage 40 fuel tank 50 PCM (estimating means, deceleration fuel cut means, deceleration fuel cut prohibition means, deceleration fuel cut stop means)
60 Automatic transmission (running resistance increasing means)
140 Third brake (brake element)
SW2 Engine speed sensor SW3 Engine water temperature sensor SW4 Linear air-fuel ratio sensor (detection means)
SW5 Accelerator position sensor SW6 Vehicle speed sensor

Claims (5)

A spark ignition engine control device comprising an injector for injecting fuel into a cylinder and an ignition plug for igniting the injected fuel, wherein the fuel is supplied with alcohol, gasoline, or a mixed fuel thereof.
Estimating means for estimating the amount of vaporized fuel that flows into the combustion chamber after evaporating and vaporizing from the engine oil as the temperature rises, after unmixed in the engine oil in the oil pan of the fuel injected from the injector When,
Decelerating fuel cut means for performing decelerating fuel cut control for cutting off the fuel supply and spark ignition to the engine when a predetermined fuel cut condition is satisfied during deceleration traveling of the vehicle;
When the equivalence ratio obtained from the amount of vaporized fuel estimated by the estimating means is equal to or greater than a threshold set in view of whether or not the vaporized fuel is burnt afterward in the exhaust passage from the exhaust port to the catalyst device. A spark ignition engine control device comprising: a deceleration fuel cut prohibiting means for prohibiting the deceleration fuel cut control even when the fuel cut condition is satisfied. The control device for a spark ignition engine according to claim 1,
Detecting means for detecting that combustion is occurring during execution of the deceleration fuel cut control;
When the detection unit detects that combustion is occurring, the vehicle further includes a deceleration fuel cut stop unit that stops the deceleration fuel cut control being executed even when the deceleration fuel cut control is being executed. A control device for a spark ignition type engine. The control device for a spark ignition engine according to claim 1 or 2,
When the deceleration fuel cut control is prohibited or when the deceleration fuel cut control is stopped, a running resistance increasing means for increasing the running resistance of the vehicle is further provided during the deceleration fuel cut control that should be performed. A control device for a spark ignition engine. The control device for the spark ignition engine according to claim 3,
The spark ignition engine control apparatus, wherein the running resistance increasing means slips a brake element in a transmission that is opened when the deceleration fuel cut control is executed. The control device for a spark ignition engine according to claim 3 or 4,
A spark ignition type engine control device characterized in that the running resistance increasing means generates power from an alternator driven by an output shaft of the engine.

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