JP2010090870A - Blowby gas treatment device of internal combustion engine - Google Patents

Abstract

To prevent sludge from being easily generated in oil of an internal combustion engine when a fuel containing alcohol is used, and to prevent the generation of sludge from adversely affecting lubrication by the oil in the engine. To do.
When the alcohol concentration of the fuel is high, the flow rate of the blow-by gas returned from the crankcase to the intake passage is higher than when the alcohol concentration in the fuel is low, such as when using fuel with an alcohol concentration of 0%. The amount of the blowby gas containing a large amount of moisture increases and is quickly returned to the intake passage 3. Accordingly, it is suppressed that sludge is easily generated in the oil of the engine 1 when the fuel containing alcohol is used, and the generation of the sludge is suppressed from adversely affecting the lubrication by the oil in the engine 1. The
[Selection] Figure 1

Description

  The present invention relates to a blow-by gas processing apparatus for an internal combustion engine.

  In an internal combustion engine mounted on a vehicle such as an automobile, a gas containing a fuel component and an exhaust component (blow-by gas) leaks from a combustion chamber to a crankcase through a space between a cylinder inner wall and a piston ring during operation. When blow-by gas leaks from the combustion chamber to the crankcase, exhaust components (NOx, SOx, etc.) in the gas, olefins contained in the oil in the crankcase of the internal combustion engine, and moisture in the case are heated. It is known that sludge is generated in oil by reacting with an acid (see Patent Document 1). If such sludge is generated on the oil flow path in the internal combustion engine, it will adversely affect the lubrication by the oil in the internal combustion engine.

In consideration of leakage of blow-by gas from the combustion chamber into the crankcase during operation of the internal combustion engine, for example, as shown in Patent Document 2, the blow-by gas is returned from the crank case to the intake passage and processed. It is also conceivable to provide a gas treatment device. In this case, since blow-by gas leaking from the combustion chamber to the crankcase is returned to the intake passage, sludge generation in the oil of the internal combustion engine due to exhaust components in the gas can be suppressed.
JP 2008-121474 A (paragraph [0002]) JP-A-6-81625

  By the way, as a fuel for an internal combustion engine, not only a fuel composed only of gasoline but also a mixed fuel of alcohol and gasoline or an alcohol fuel composed only of alcohol may be used.

  In an internal combustion engine, when such alcohol-containing fuel is combusted, the amount of water (water vapor) per unit volume in the exhaust of the engine is larger than when fuel consisting only of gasoline is combusted. The amount of moisture per unit volume in the blow-by gas that leaks from the combustion chamber to the crankcase also increases. In particular, the higher the alcohol concentration in the fuel, the greater the amount of moisture in the exhaust gas, and the greater the amount of moisture in the blow-by gas that leaks from the fuel chamber to the crankcase.

  For this reason, in an internal combustion engine in which alcohol-containing fuel is used, the blow-by gas leaked from the combustion chamber into the crankcase is returned to the intake passage by the blow-by gas processing device, assuming the use of fuel consisting only of gasoline. Even so, it is unavoidable that the amount of water present in the case increases. And it becomes easy to produce | generate sludge in the oil of an internal combustion engine resulting from the increase in the quantity of the water | moisture content. As described above, the sludge is easily generated in the oil of the internal combustion engine as described above, and when the sludge is generated in the oil flow path in the engine, the lubrication by the oil in the internal combustion engine is adversely affected. .

  The present invention has been made in view of such circumstances, and the object thereof is to suppress the generation of sludge easily in the oil of an internal combustion engine when using a fuel containing alcohol, and the generation of the sludge. An object of the present invention is to provide a blow-by gas processing apparatus for an internal combustion engine that can suppress adverse effects on lubrication by the oil in the engine.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, the blow-by gas leaked from the combustion chamber of the internal combustion engine to the crankcase is returned to the intake passage, and the gas flow rate of the blow-by gas returned to the intake passage is set to the engine operating state. In the blow-by gas processing apparatus for an internal combustion engine that is controlled on the basis of the above, there is provided control means for increasing the gas flow rate of the blow-by gas that is returned to the intake passage when the alcohol concentration of the fuel of the internal combustion engine is high compared to when it is low.

  In an internal combustion engine, if blow-by gas leaks from the combustion chamber to the crankcase during operation, exhaust components (NOx, SOx, etc.) in the gas, olefins contained in the oil in the crankcase of the internal combustion engine, and the case There is a possibility that sludge is generated in the oil by reacting with the moisture in the inside by heat or acid. Regarding such sludge in oil, generation of blow-by gas leaked from the combustion chamber to the crankcase is returned to the intake passage by the blow-by gas processing device, thereby suppressing generation of the sludge.

  However, when alcohol-containing fuel is used, the amount of moisture (water vapor) per unit volume in the blow-by gas that leaks from the combustion chamber into the crankcase increases. For this reason, even if the blow-by gas is returned from the crank case to the intake passage by the blow-by gas processing device assuming the use of fuel consisting only of gasoline (fuel having an alcohol concentration of 0%), the blow-by gas exists in the crank case. It is inevitable that the amount of moisture increases. And when the amount of water present in the crankcase increases, sludge is easily generated in the oil of the engine. In this way, sludge is easily generated in the oil of the internal combustion engine, and if sludge is generated in the oil flow path in the engine, it adversely affects the lubrication by the oil in the engine.

  According to the above configuration, when the alcohol concentration of the fuel is high, the flow rate of the blow-by gas returned from the crankcase to the intake passage is smaller than when the alcohol concentration in the fuel is low, such as when using fuel with an alcohol concentration of 0%. The amount of the blowby gas containing a large amount of water is increased and returned to the intake passage quickly. As a result, an increase in the amount of moisture present in the crankcase is suppressed, and the amount of exhaust components (NOx, SOx, etc.) in the gas present in the crankcase is reduced. Therefore, when using fuel containing alcohol, sludge is likely to be generated in the oil of the internal combustion engine, and sludge is generated in the oil flow path in the engine, which adversely affects the lubrication by the oil in the engine. That will be suppressed.

  According to a second aspect of the present invention, in the first aspect of the invention, the internal combustion engine includes a gas outflow passage for returning blowby gas leaked from the combustion chamber to the crankcase to the intake passage, and a gas in the gas outflow passage. A PCV valve that opens and closes to make the flow area variable, and the PCV valve is adjusted in opening based on an opening command value calculated in accordance with an engine operating state, thereby passing through the gas outflow passage. The flow rate of blow-by gas returned to the intake passage is controlled, and the control means sets the opening degree command value to a value on the opening side when the alcohol concentration of the fuel is high compared to when the alcohol concentration is low. It was set as the summary.

  According to the above configuration, when the alcohol concentration in the fuel is high, the opening command value is a value on the open side compared to when the alcohol concentration in the fuel is low, such as when using fuel with an alcohol concentration of 0%. The opening degree of the PCV valve is adjusted based on the degree command value. Therefore, the gas flow rate of the blow-by gas returned from the crankcase to the intake passage through the gas outflow passage can be accurately increased when the alcohol concentration in the fuel is high compared to when the concentration is low. .

  According to a third aspect of the present invention, in the second aspect of the present invention, the control means selects a map corresponding to the actual alcohol concentration from among a plurality of maps prepared according to the alcohol concentration of the fuel, and selects the map. The gist is to calculate the opening command value based on the engine operating state with reference to the map.

  The more the maps for calculating the PCV valve opening command value are prepared in accordance with the subtle differences in the alcohol concentration in the fuel, the more optimal the opening command value is in accordance with the alcohol concentration in the fuel. It becomes possible to make it fine and variable. However, if a large number of the maps are prepared according to the small difference in the alcohol concentration in the fuel, it takes a lot of time and effort. In the above configuration, both the setting of the opening command value to the optimum value according to the alcohol concentration in the fuel and the time for preparing the map are omitted, and the same is set so that each is optimum. The number of maps can be determined as appropriate.

  According to a fourth aspect of the present invention, in the second aspect of the invention, the control means calculates a correction value based on the alcohol concentration of the fuel, and corrects the opening degree command value using the correction value. The same opening degree command value is set to a value on the open side when the alcohol concentration is high compared to when the alcohol concentration is low.

  According to the above configuration, it is only necessary to newly perform the process of correcting the opening command value of the PCV valve, and the existing process can be used for the process of calculating the opening command value before the correction. For this reason, when the alcohol concentration of the fuel is high, the opening degree command value can be easily set to a value on the open side as compared with the case where the alcohol concentration is low.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the control means is configured such that the higher the alcohol concentration of the fuel, the larger the opening command value becomes a value on the open side so that the opening command value becomes a larger open side value. The gist is to gradually change the correction value in accordance with the change to.

  According to the above configuration, since the opening degree command value of the PCV valve can be finely varied according to the alcohol concentration in the fuel, even if the alcohol concentration in the fuel fluctuates finely for each fuel supply, In addition, the opening degree command value can be set to a value suitable for the alcohol concentration.

  Hereinafter, an embodiment in which the present invention is applied to an automobile engine in which a fuel containing alcohol, such as a mixed fuel of gasoline and alcohol or an alcohol fuel composed only of alcohol, is used as a fuel will be described with reference to FIGS. I will explain.

  In the engine 1 shown in FIG. 1, an intake passage 3 and an exhaust passage 4 are connected to a combustion chamber 2 of each cylinder. Then, air is sucked into the combustion chamber 2 through the intake passage 3 provided with the throttle valve 11 for adjusting the intake air amount of the engine 1 and fuel is injected into the intake passage 3 from the fuel injection valve 5. By being supplied, the combustion chamber 2 is filled with a mixture of air and fuel. When this air-fuel mixture burns based on ignition by the spark plug 6 of each cylinder, the piston 7 reciprocates due to the combustion energy at that time, and the crankshaft 8 that is the output shaft of the engine 1 rotates. Further, the air-fuel mixture after combustion is sent to the exhaust passage 4 as exhaust gas.

  In the engine 1, part of the gas present in the combustion chamber 2 leaks into the crankcase 10 from between the piston ring 7 a and the cylinder inner wall 9 as blow-by gas in the compression stroke and the expansion stroke. For this reason, the engine 1 is provided with a blow-by gas processing device that returns the blow-by gas leaked from the combustion chamber 2 to the intake passage 3 for processing.

  The apparatus is connected to a portion of the intake passage 3 upstream of the throttle valve 11 and introduces fresh air into the crankcase 10, and returns the blow-by gas in the crankcase 10 to the intake passage 3. Accordingly, a gas outflow passage 13 connected to the downstream side of the throttle valve 11 in the passage 3 is provided. The gas outflow passage 13 is provided with a PCV valve 14 for adjusting the gas flow rate when the blowby gas is returned to the intake passage 3. The PCV valve 14 is an electric type whose opening is adjusted by a step motor or the like, and increases the flow rate of gas flowing from the gas outflow passage 13 to the intake passage 3 as the opening is adjusted to the open side. It is. In the apparatus, blow-by gas leaking from the combustion chamber 2 into the crankcase 10 is returned to the intake passage 3 through the gas outflow passage 13 by introducing fresh air from the fresh air introduction passage 12 into the crankcase 10. It comes to be.

Next, the electrical configuration of the blow-by gas processing apparatus will be described.
The blow-by gas processing apparatus includes an electronic control device 19 that is mounted on an automobile and executes various controls related to the engine 1 and the like. The electronic control unit 19 includes a CPU that executes various arithmetic processes related to the above control, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores arithmetic results of the CPU, and the like. An input / output port for inputting / outputting signals is provided.

Various sensors shown below are connected to the input port of the electronic control unit 19.
An accelerator position sensor 21 that detects the amount of depression (accelerator depression amount) of the accelerator pedal 20 that is depressed by the driver of the automobile.

A throttle position sensor 22 that detects the opening (throttle opening) of the throttle valve 11 provided in the intake passage 3 of the engine 1.
An air flow meter 23 that detects the amount of air that passes through the intake passage 3 and is sucked into the combustion chamber 2.

A crank position sensor 24 that outputs a signal corresponding to the rotation of the crankshaft 8.
An air-fuel ratio sensor 26 that outputs a signal corresponding to the oxygen concentration in the exhaust gas.

A knock sensor 31 that detects occurrence of knock in the engine 1.
An open / close sensor 35 that detects opening / closing of the lid at the fuel filler port of the fuel tank in order to determine the presence or absence of fuel supply.

The output port of the electronic control unit 19 is connected to drive circuits for various devices such as the fuel injection valve 5, the spark plug 6, the throttle valve 11, and the PCV valve 14.
The electronic control unit 19 outputs a command signal to the drive circuit of each device connected to the output port according to the engine operating state grasped from the detection signal input from each sensor. In this way, the electronic control unit 19 performs various controls such as ignition timing control of the spark plug 6, throttle valve 11 opening control, fuel injection control by the fuel injection valve 5, and PCV valve 14 opening control.

  Examples of the fuel injection control by the fuel injection valve 5 include fuel injection amount control including air-fuel ratio feedback correction of the fuel injection amount. The air-fuel ratio feedback correction of the fuel injection amount is performed by increasing or decreasing the air-fuel ratio feedback correction value for correcting the fuel injection amount based on the output of the air-fuel ratio sensor 26 or the like so that the air-fuel ratio of the engine 1 becomes the stoichiometric air-fuel ratio. This is realized by performing the above correction with the same air-fuel ratio feedback correction value.

  Further, as the ignition timing control of the spark plug 6, for example, KCS control that corrects the ignition timing to the advance side limit while suppressing knocking in the engine 1 in order to improve the output of the engine 1 and improve fuel efficiency. can give. The KCS control is realized by changing the feedback correction term for correcting the ignition timing to the advance angle correction side when no knock occurs and to the retard angle correction side when knock occurs.

Next, an outline of the opening degree control of the PCV valve 14 will be described.
The opening degree control value of the PCV valve 14 is an opening degree command value obtained by the electronic control unit 19 for the purpose of controlling the gas flow rate of blowby gas returned from the crankcase 10 to the intake passage 3 via the gas outflow passage 13. This is performed based on the command step number R.

  Specifically, the command step number R is calculated with reference to a preset map based on the engine operating state such as the engine rotation speed and the engine load, and the PCV valve 14 is opened and closed based on the command step number R. The engine speed used for calculating the command step number R is obtained based on a detection signal from the crank position sensor 24. The engine load is calculated from a parameter corresponding to the intake air amount of the engine 1 and the engine speed. The parameters corresponding to the intake air amount used here include, for example, an actually measured value of the intake air amount of the engine 1 obtained based on a detection signal from the air flow meter 23, a throttle opening detected by the throttle position sensor 22, and the like. Is used.

  The PCV valve 14 whose opening degree is controlled as described above is fully closed when the command step number R is “0”, and the opening degree is adjusted as the command step number R increases from “0”. Is done. Through such opening degree control of the PCV valve 14, the flow rate of blow-by gas flowing from the crankcase 10 to the intake passage 3 via the gas outflow passage 13 is controlled. More specifically, for example, FIG. 2 shows the gas flow rate with respect to a change in the intake pressure of the engine 1 that changes according to changes in the engine load and the engine speed, that is, a change in pressure on the downstream side of the throttle valve 11 in the intake passage 3. It is made to change as shown with a dashed-two dotted line.

  If the flow rate of the blowby gas is too small, exhaust oil and unburned fuel components in the blowby gas leaking from the combustion chamber 2 are mixed with the oil in the crankcase 10, and the oil is likely to deteriorate. If it is too much, the amount of oil taken away to the passage 3 by blow-by gas returned to the intake passage 3 increases, and deposits in the passage 3 are attached. Therefore, regarding the command step number R used for controlling the gas flow rate of the blow-by gas, the engine rotational speed is set so that the gas flow rate becomes an optimum value based on the two points such as the deterioration of the oil and the adhesion of the deposit. It is also possible to calculate based on the engine load.

  By the way, in the engine 1 in which the fuel containing alcohol is used, the blow-by gas leaked from the combustion chamber 2 into the crankcase 10 is blown by assuming that the fuel (fuel having an alcohol concentration of 0%) consisting only of gasoline is used. Even if it is made to return to the intake passage 3 by the gas processing device, it is inevitable that the amount of moisture present in the case 10 increases. And it becomes easy to produce | generate sludge in the oil of the engine 1 resulting from the increase in the quantity of the water | moisture content. In particular, when the alcohol concentration in the fuel is high, the amount of moisture in the exhaust gas increases, and the amount of moisture in the blow-by gas that leaks from the fuel chamber to the crankcase also increases. Sludge is easily generated. If sludge is generated in the oil flow path of the engine 1 as described above, it will adversely affect the lubrication of the engine 1 with the oil.

  In order to deal with such problems, in this embodiment, the flow rate of blow-by gas returned from the crankcase 10 to the intake passage 3 is increased when the alcohol concentration of the fuel of the engine 1 is high compared to when it is low.

  Here, when the alcohol concentration of the fuel is high, the amount per unit deposition in the blow-by gas leaking from the combustion chamber 2 to the crankcase 10 is lower than when the alcohol concentration in the fuel is low, such as when using fuel with an alcohol concentration of 0%. Although the amount of moisture (water vapor) increases, the gas is returned to the intake passage 3 quickly and rapidly through the control of the gas flow rate. Therefore, an increase in the amount of moisture present in the crankcase 10 is suppressed, and an amount of exhaust components (NOx, SOx, etc.) present in the crankcase 10 is reduced.

  As described above, it is suppressed that sludge is easily generated in the oil of the engine 1 when the fuel containing alcohol is used, and the generation of the sludge is suppressed from adversely affecting the lubrication by the oil in the engine 1. Become so.

  Next, details of the opening degree control of the PCV valve 14 of the present embodiment for the purpose of controlling the flow rate of blow-by gas returned to the intake passage 3 will be described with reference to the flowchart of FIG. 3 showing the PCV valve control routine. To do. This PCV valve control routine is periodically executed through the electronic control unit 19 by, for example, a time interruption every predetermined time.

In this routine, first, an estimated value of the alcohol concentration in the fuel stored in the nonvolatile RAM of the electronic control unit 19 is read (S101).
The estimated value of the alcohol concentration is obtained for each refueling using, for example, an air-fuel ratio feedback correction value used for air-fuel ratio feedback correction of the fuel injection amount. That is, at the time of the first engine operation after refueling, there is a high possibility that the alcohol concentration in the fuel changes from the value before refueling, and when the alcohol concentration changes, the air-fuel ratio feedback correction is performed. The air-fuel ratio feedback correction value at that time changes from the value before refueling by an amount corresponding to the change in the alcohol concentration. This is because the alcohol combustion characteristic is different from the gasoline combustion characteristic, and the theoretical air-fuel ratio of the fuel becomes the theoretical air-fuel ratio when only gasoline is the fuel as the alcohol concentration in the fuel increases. This is because the air-fuel ratio feedback correction value changes to a value on the fuel injection amount increase correction side (a value on the increase side). Therefore, when the change in the air-fuel ratio feedback correction value occurs, the estimated value stored in the non-volatile RAM is increased or decreased according to the change, so that the estimated value corresponds to the actual alcohol concentration in the fuel. Value. As an initial value of the estimated value that is increased or decreased as described above, for example, a general alcohol concentration (22% or the like) in a fuel in which gasoline and alcohol are mixed is used.

  Further, instead of using the air-fuel ratio feedback correction value as described above, the estimated value of the alcohol concentration in the fuel may be determined for each fuel supply using a feedback correction term used in KCS control. Here, during the first engine operation after refueling, if the alcohol concentration in the fuel changes from the value before refueling, the feedback correction term used in KCS control corresponds to the change in the alcohol concentration relative to the value before refueling. Change by minutes. This is because the combustion characteristic of alcohol is different from that of gasoline, and the higher the alcohol concentration in the fuel, the less likely knocking occurs in the engine 1, and the feedback correction value is greater on the ignition timing advance correction side. This is because it changes to a value. Therefore, when the feedback correction value changes, the estimated value stored in the nonvolatile RAM is increased or decreased according to the change, so that the estimated value corresponds to the actual alcohol concentration in the fuel. It is said. As for the initial value of the estimated value that is increased or decreased as described above, the general alcohol concentration (22% or the like) in the fuel in which gasoline and alcohol are mixed is used as described above.

  As described above, increasing or decreasing the estimated value stored in the non-volatile RAM of the electronic control unit 19 in accordance with the change in the alcohol concentration in the fuel due to refueling estimates the alcohol concentration in the fuel for each refueling. Means that In step S101, the alcohol concentration (estimated value) estimated in this way and stored in the nonvolatile RAM of the electronic control unit 19 is read. Then, based on the read alcohol concentration, processing (S102 to S105) is performed to increase the flow rate of blow-by gas returned from the crankcase 10 to the intake passage 3 when the concentration is high compared to when the concentration is low.

  In this series of processing, when the alcohol concentration in the fuel is high, increasing the gas flow rate as compared with when the alcohol concentration is low is the same as the command step number R used for opening degree control of the PCV valve 14 when the alcohol concentration is high. This is realized by setting the value on the open side (value on the increase side) compared to the case where the density is low.

  Specifically, as a map for calculating the command step number R, among the maps prepared as shown in FIG. 4 according to the alcohol concentration in the fuel, the alcohol concentration read in step S101 is used. A corresponding map is selected (S102 in FIG. 3). In this embodiment, as the map, three types of maps corresponding to when the alcohol concentration in the fuel is low, medium, and high are determined in advance by experiments or the like and stored in the ROM of the electronic control unit 19. Has been. Incidentally, specific values of the low, medium and high alcohol concentrations are, for example, values of “0% (gasoline 100%)”, “22%” and “100%”, respectively. In the processing in step S102, the alcohol concentration read in step S101 is selected from the maps corresponding to the three types of alcohol concentrations “0% (gasoline 100%)”, “22%”, and “100%”. The map corresponding to the closest alcohol concentration is selected.

  Subsequently, the command step number R is calculated based on the engine operating state such as the engine load and the engine speed with reference to the map selected as described above (S103). The command step number R calculated in this way becomes a value on the open side (a value on the increase side) when the alcohol concentration in the fuel is high compared to when it is low. That is, the three types of maps are determined so that the command step number R is calculated as such a value. Then, the opening degree of the PCV valve 14 is adjusted based on the calculated command step number R, thereby adjusting the flow rate of blow-by gas returned to the intake passage 3.

  FIG. 2 is a graph showing the transition of the flow rate of blow-by gas returned to the intake passage 3 with respect to the change in the intake pressure of the engine 1. The two-dot chain line in the figure shows the transition of the gas flow rate when the command step number R is calculated with reference to the corresponding map when the alcohol concentration in the fuel is low (in this example, “0%”). Is shown. The broken line shows the transition of the gas flow rate when the command step number R is calculated with reference to the corresponding map when the alcohol concentration is a medium concentration (in this example, “22%”). Further, the solid line shows the transition of the gas flow rate when the command step number R is calculated with reference to the map corresponding to the alcohol concentration being high (in this example, “100%”). As can be seen from the figure, the flow rate of blow-by gas returned to the intake passage 3 is low when the alcohol concentration in the fuel is high, corresponding to the opening degree adjustment of the PCV valve 14 based on the command step number R. It will be increased compared to.

According to the embodiment described in detail above, the following effects can be obtained.
(1) When the alcohol concentration of the fuel is high, the flow rate of blow-by gas returned from the crankcase 10 to the intake passage 3 is larger than when the alcohol concentration in the fuel is low, such as when using fuel with an alcohol concentration of 0%. The blowby gas containing a large amount of moisture is returned to the intake passage 3 quickly and quickly. Accordingly, it is suppressed that sludge is easily generated in the oil of the engine 1 when the fuel containing alcohol is used, and the generation of the sludge is suppressed from adversely affecting the lubrication by the oil in the engine 1. The

  (2) A PCV valve 14 is provided in the gas outflow passage 13 through which the blow-by gas returned to the intake passage 3 flows, and the opening degree of the PCV valve 14 is adjusted based on the command step number R. When the alcohol concentration in the fuel is high, the command step number R is set to a value closer to the open side than when the alcohol concentration in the fuel is low, such as when using a fuel with an alcohol concentration of 0%. Accordingly, the flow rate of the blow-by gas returned to the intake passage 3 can be accurately increased when the alcohol concentration in the fuel is high compared to when the concentration is low.

  (3) A plurality of maps corresponding to the alcohol concentration of the fuel are prepared as maps for calculating the command step number R, and a map corresponding to the estimated value of the alcohol concentration is selected from these maps. The command step number R is calculated based on the engine operating state with reference to the selected map. Here, the more the maps for calculating the command step number R are prepared according to the subtle differences in the alcohol concentration in the fuel, the more the command step number R is set to an optimum value according to the alcohol concentration in the fuel. It becomes possible to make it as finely variable as possible. However, if it is attempted to prepare a large number of the maps in accordance with the small difference in the alcohol concentration in the fuel, it takes a lot of time and effort for experiments and the like necessary to define the maps. Based on this situation, each of them is optimized so that both the setting of the command step number R in accordance with the alcohol concentration in the fuel and the trouble of preparing the map can be saved. The number of the maps can be determined appropriately.

In addition, each said embodiment can also be changed as follows, for example.
As the map for calculating the command step number R, two types of maps corresponding to the alcohol concentration may be used, or four or more types of maps may be used. As the number of maps increases, the command step number R can be made finer and variable so as to be an optimum value according to the alcohol concentration in the fuel.

  The command step number R may be calculated using a calculation formula determined in advance by experiments or the like based on the alcohol concentration in the fuel, the engine load, and the engine speed. In this case, the command step number R can be finely varied so as to be an optimum value according to the alcohol concentration in the fuel.

  The command step number R corresponding to when the alcohol concentration in the fuel is 0% (fuel of 100% gasoline) is calculated using a map or a calculation formula based on the engine operating state, and the command step thus calculated The number R may be corrected with a correction value H that is variable according to the alcohol concentration in the fuel. The correction value H depends on the alcohol concentration so that when the alcohol concentration in the fuel is high, the command step number R is corrected to the increase side (opening side of the PCV valve 14) compared to when it is low. Variable.

  In this case, regarding the calculation process of the command step number R, a calculation process in a conventional engine using only gasoline as fuel can be used, and the command step number R calculated by the calculation process is used as the correction value H. It is only necessary to newly add a process to be corrected by. Therefore, the command step number R can be easily set to a value on the open side when the alcohol concentration of the fuel is high compared to when the alcohol concentration is low.

  -Regarding the change of the correction value H, a map corresponding to the current alcohol concentration is selected from a plurality of maps prepared according to the alcohol concentration in the fuel, and the alcohol concentration is set to the same alcohol concentration by referring to the selected map. It is possible to calculate based on this. In this case, if the number of the maps is increased, the correction value H can be finely changed so as to become an optimum value according to the alcohol concentration. However, it takes a lot of time and labor for the experiment necessary to determine the map. Therefore, regarding the number of maps, it is preferable that the correction value H is an optimum value according to the alcohol concentration and that the time required for preparing the map can be saved.

  Further, the correction value H may be calculated using a calculation formula determined in advance by experiments or the like based on the alcohol concentration in the fuel. In this case, the correction value H is gradually changed in accordance with the change in the alcohol concentration to the deeper side so that the command step number R is corrected to a larger opening side value (increase side value) as the alcohol concentration in the fuel becomes higher. It becomes possible to make it. Thus, by making the correction value H finely variable so as to be an optimum value according to the alcohol concentration in the fuel, even if the alcohol concentration in the fuel varies finely for each fuel supply, the above command is adjusted in accordance with the variation. The number of steps R can be set to a value suitable for the alcohol concentration.

  An alcohol concentration sensor that detects the alcohol concentration in the fuel may be provided, and the gas flow rate of the blow-by gas returned to the intake passage 3 may be variable using the alcohol concentration detected by the sensor.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole engine with which the blowby gas processing apparatus of this embodiment is applied. The graph which shows transition of the gas flow rate of the blow-by gas returned to an intake passage with respect to the change of the intake pressure of an engine. The flowchart which shows the opening degree control procedure of a PCV valve. The map used in order to calculate the command step number R which is a PCV valve opening command value.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Combustion chamber, 3 ... Intake passage, 4 ... Exhaust passage, 5 ... Fuel injection valve, 6 ... Spark plug, 7 ... Piston, 7a ... Piston ring, 8 ... Crankshaft, 9 ... Cylinder inner wall, 10 DESCRIPTION OF SYMBOLS ... Crankcase, 11 ... Throttle valve, 12 ... Fresh air introduction passage, 13 ... Gas outflow passage, 14 ... PCV valve, 19 ... Electronic control unit (control means), 20 ... Accelerator pedal, 21 ... Accelerator position sensor, 22 ... Throttle position sensor, 23 ... air flow meter, 24 ... crank position sensor, 26 ... air-fuel ratio sensor, 31 ... knock sensor, 35 ... open / close sensor.

Claims (5)

In the blow-by gas processing apparatus for an internal combustion engine that controls the flow rate of the blow-by gas returned to the intake passage along with the return of the blow-by gas leaked to the crankcase from the combustion chamber of the internal combustion engine based on the engine operating state,
A blow-by gas processing apparatus for an internal combustion engine, comprising: control means for increasing the flow rate of the blow-by gas returned to the intake passage when the alcohol concentration of the fuel of the internal combustion engine is high compared to when the alcohol concentration is low. The internal combustion engine includes a gas outflow passage for returning blowby gas leaked from the combustion chamber to the crankcase to the intake passage, and a PCV valve that opens and closes to make the gas flow area of the gas outflow passage variable.
The PCV valve adjusts the opening based on an opening command value calculated according to the engine operating state, thereby controlling the gas flow rate of blow-by gas returned to the intake passage through the gas outflow passage. Yes,
The blow-by gas processing apparatus for an internal combustion engine according to claim 1, wherein the control means sets the opening degree command value to a value on the open side when the alcohol concentration of the fuel is high compared to when the alcohol concentration is low. The control means selects a map corresponding to an actual alcohol concentration from among a plurality of maps prepared in accordance with the alcohol concentration of the fuel, and refers to the selected map based on the engine operation state and the opening command value. The blow-by gas processing apparatus for an internal combustion engine according to claim 2. The control means calculates a correction value based on the alcohol concentration of the fuel, and corrects the opening command value using the correction value. The blow-by gas processing device for an internal combustion engine according to claim 2, wherein the value is on the open side compared to when the concentration is low. The control means gradually changes the correction value according to a change to the richer side of the alcohol concentration so that the opening command value becomes a larger opening side value as the alcohol concentration of the fuel becomes higher. Blow-by gas processing equipment.

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