JP5691755B2 - Engine blow-by gas control device - Google Patents

Description

  The present invention relates to an engine blow-by gas control device, and more particularly to an engine blow-by gas control device capable of preventing freezing of an intake flow rate control valve due to moisture contained in the blow-by gas.

  In an internal combustion engine (hereinafter referred to as an engine), unburned gas (blow-by gas) may leak into the crank chamber from between a piston ring and a cylinder. Since this blow-by gas is strongly acidic containing a large amount of hydrocarbons (HC) and moisture, a blow-by gas recirculation device that recirculates the blow-by gas using intake negative pressure is provided to collect the leaked blow-by gas. The recovered blowby gas is reburned in the combustion chamber.

  Usually, the blow-by gas recirculation device communicates the upstream blow-by gas recirculation passage that connects the upstream side of the intake flow control valve (throttle valve) and the crank chamber, and the downstream side of the throttle valve and the crank chamber via the cylinder head. The downstream blowby gas recirculation passage and a PCV valve (Positive Crankcase Ventilation valve) provided in the middle of the downstream blowby gas recirculation passage. The PCV valve is urged to a closed state by the urging force of the compression spring, and is configured to open against the urging force of the compression spring when the intake negative pressure is equal to or higher than a preset reference pressure. Yes. Thereby, the blow-by gas in the crank chamber is guided to the downstream blow-by gas recirculation passage when the intake negative pressure downstream of the throttle valve is equal to or higher than the reference pressure, and when the intake negative pressure downstream of the throttle valve is less than the reference pressure, It is guided to the upstream blow-by gas recirculation passage and recirculated to the combustion chamber.

  The blow-by gas recirculation device described in Patent Document 1 includes a throttle valve that can adjust the amount of intake air supplied to the engine by an electric signal that is linked to the operation of an accelerator pedal, and the opening of the throttle valve according to the operating state of the engine. A throttle valve control means for controlling, a first communication path communicating with the downstream side of the throttle valve and provided with a PCV valve in the middle, and a second communication path communicating with the upstream side of the throttle valve; The means controls the opening degree of the throttle valve at the engine full load to an opening degree smaller than the fully opened state when the engine speed is lower than the reference speed.

  In cold districts, etc., when there is a lot of water in the refluxing blow-by gas, immediately after the engine starts, water adheres between the throttle valve and the throttle body that houses the throttle valve. May cause engine malfunction. Therefore, measures are taken to prevent icing of the throttle valve by adopting a structure in which a warm water passage is formed in the throttle body and the engine coolant that has been heated is passed through the warm water passage, or a heater is installed around the throttle body. It has been.

JP 2010-121580 A

  The inventors have detected that the amount of water contained in the blow-by gas in the crank chamber increases rapidly after a predetermined time has elapsed since the engine was started. In addition, even when the engine is operating under the same conditions, there are cases where the amount of water contained in the blowby gas increases suddenly as described above and when the amount of water contained in the blowby gas does not increase suddenly. I found out.

As a result of intensive studies by the present inventors, it has been found that the above-described phenomenon of moisture increase in blow-by gas occurs by the following mechanism.
The blow-by gas staying in the crank chamber contains a large amount of moisture (water vapor) generated during combustion in addition to HC. When the engine temperature drops to near the dew point temperature after the engine is stopped, the moisture condenses on the walls of the crank chamber and oil pan, and the condensed moisture accumulates in the engine oil inside the oil pan through the wall. The In cold regions such as cold regions and winter, there is a particularly high tendency for condensation of steam in the crank chamber, and the amount of accumulated water accumulated in the oil pan tends to increase.

  As shown in FIG. 8, when the accumulated water amount accumulated in the engine oil accommodated in the oil pan exceeds a predetermined amount, after a predetermined time has elapsed since the engine started, the cooling water temperature Tw and the oil temperature To When the temperature rises to a predetermined temperature, the accumulated moisture starts to vaporize from the time ta when the so-called engine is warmed up, and steam V is generated abruptly. The generated steam V is mixed with blow-by gas in the crank chamber. Is done. Thereafter, at a time point tb when the cooling water temperature Tw and the oil temperature To rise further after a predetermined time has elapsed from the start of vaporization of accumulated moisture, vaporization of accumulated moisture is almost completed and generation of steam V is also stopped. That is, during the accumulated moisture vaporization period (between ta and tb), the vaporized vapor V (corresponding to the accumulated moisture amount) is added to the blowby gas staying in the crank chamber in addition to the originally contained moisture amount. Therefore, the moisture increase phenomenon of the blow-by gas as described above occurs. In addition, the sudden vaporization phenomenon of accumulated moisture during the accumulated moisture vaporization period is a characteristic that occurs remarkably when it exceeds the accumulation tolerance that can be set by external factors such as the environment and internal factors such as engine displacement. There is.

  In the blow-by gas recirculation device described in Patent Document 1, the opening degree of the throttle valve at full load is controlled to be smaller than the full opening degree in the middle speed range where the engine speed is lower than the reference speed. The negative pressure at the downstream portion of the throttle valve in the middle rotation range can be adjusted to be higher than the reference pressure, the flow rate of blow-by gas passing through the second communication passage can be reduced, and the oil separator structure is simplified. In addition, since this blow-by gas recirculation device reduces the flow rate of blow-by gas passing through the second communication passage, icing of the throttle valve can be suppressed. However, since the blow-by gas recirculation device of Patent Document 1 is controlled so that the opening of the throttle valve is smaller than fully open when the engine speed is in the middle rotation range, the icing of the throttle valve can be suppressed. There is a risk that the output of the engine is sacrificed and the output efficiency is lowered.

  In addition, when a hot water passage is formed in the throttle body or a heater is installed in the throttle body to prevent icing of the throttle valve, the structure becomes complicated and the number of parts increases, resulting in high engine manufacturing costs. There is a risk of becoming. Moreover, when the possibility of icing is low, the amount of water contained in the blow-by gas does not increase abruptly when the possibility of icing is low (the amount of accumulated water is low and the allowable storage value is low). Therefore, there is a concern that the fuel consumption of the engine may be reduced.

  An object of the present invention is to provide an engine blow-by gas control device capable of suppressing freezing of an intake flow rate control valve while maintaining output efficiency of the engine.

  An engine blow-by gas control device according to claim 1 is an intake flow control valve capable of adjusting an intake air amount supplied to the engine by an electric signal interlocked with an operation of an accelerator pedal, an upstream side of the intake flow control valve, a crank chamber, An upstream blow-by gas recirculation passage, and a downstream blow-by gas recirculation passage communicating the downstream side of the intake flow control valve and the crank chamber, and a PCV valve is provided in the middle of the downstream blow-by gas recirculation passage. In the engine blowby gas control device provided, the normal opening control for controlling the intake flow control valve to an opening corresponding to the operation of the accelerator pedal and the intake flow control valve lower than the opening corresponding to the operation of the accelerator pedal. Intake flow rate control means that can perform low opening degree control that controls to the opening side, and whether the accumulated moisture accumulated in the oil pan has reached a predetermined amount And a water recirculation passage switching means for causing the intake air flow control means to perform low opening degree control when it is determined that the accumulated water content has reached a predetermined value and the engine is in a high load operation state. It is characterized by having.

  In this engine blow-by gas control device, the moisture amount determination means determines whether or not the accumulated moisture accumulated in the oil pan has reached a predetermined amount. It is possible to determine the possibility of occurrence of the moisture increase phenomenon of blow-by gas.

According to a second aspect of the present invention, in the first aspect of the present invention, when the recirculation passage switching means determines that the accumulated water amount has reached a predetermined value and the intake flow control valve is fully open, the intake flow control means It is characterized by operating the low opening control.
According to a third aspect of the present invention, in the first or second aspect of the invention, the recirculation passage switching means generates the negative pressure at which the PCV valve is fully opened on the downstream side of the intake flow control valve. It is characterized by operating the low opening degree control by.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the recirculation passage switching means is configured such that at least one of the duration of the low opening control and the engine temperature reaches a set value. The low opening degree control by the intake air flow rate control means is canceled.
According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the moisture amount determination means starts the engine at a low outside air temperature and a low engine temperature and before the engine temperature reaches a predetermined temperature. The accumulated water amount generated during the engine cold operation when the engine is stopped is estimated, and the accumulated water amount generated during the engine cold operation is accumulated every time the engine cold operation is continuously repeated, and the accumulated value is stored. It is characterized by that.

A sixth aspect of the invention is characterized in that, in the fifth aspect of the invention, the moisture amount determining means resets the integrated value when the repetition of the engine cold operation is interrupted.
A seventh aspect of the invention is characterized in that, in the fifth or sixth aspect of the invention, the water content determination means resets the integrated value when the low opening degree control by the intake flow rate control means is released. .

  According to the first aspect of the present invention, the intake flow rate control means can execute the low opening degree control that generates the negative pressure downstream of the intake flow rate control valve without causing a structural change such as the formation of a hot water passage or an increase in the number of parts. The blow-by gas can be recirculated downstream of the intake flow control valve by the upstream blow-by gas recirculation passage, and freezing of the intake flow control valve can be suppressed. In addition, the moisture amount determination means determines the possibility of occurrence of the moisture increase phenomenon of the blow-by gas, the reflux passage switching means has a high possibility of occurrence of the moisture increase phenomenon of the blow-by gas, and the negative pressure on the downstream side of the intake flow control valve is When the engine is in a small engine high-load operation state, the low opening degree control of the intake air flow rate control means is executed, so the low opening degree control period can be shortened and the reduction in engine output efficiency due to the low opening degree control can be suppressed. it can. Therefore, freezing due to moisture contained in the blow-by gas of the intake flow control valve can be suppressed while maintaining the output efficiency of the engine.

According to the second aspect of the present invention, the low opening degree control of the intake flow rate control means is executed when there is a high possibility of occurrence of the moisture increase phenomenon of the blow-by gas and no negative pressure downstream of the intake flow rate control valve is generated. In addition, the low opening degree control period can be minimized, and the engine output efficiency reduction can be further suppressed.
According to the invention of claim 3, since it is possible to prevent the generation of excessive negative pressure exceeding the supply capacity of the PCV valve on the downstream side of the intake flow control valve, it is possible to secure the intake amount of the engine and further suppress the decrease in engine output efficiency. can do.

According to the invention of claim 4, since the low opening degree control of the intake flow rate control means can be released in synchronization with the end of vaporization of the accumulated water accumulated in the oil pan, the low opening degree control period can be minimized. It is possible to further suppress the reduction in engine output efficiency.
According to the invention of claim 5, by accumulating the accumulated moisture amount accumulated in the engine cold operation per time, the accumulated moisture amount accumulated in the oil pan can be accurately grasped, and the low opening degree Control can be executed with high accuracy.

According to the invention of claim 6, the amount of accumulated water accumulated in the oil pan can be grasped more accurately, and the low opening degree control can be executed with higher accuracy.
According to the seventh aspect of the invention, the amount of accumulated water accumulated in the oil pan can be grasped more accurately, and the low opening degree control can be executed with higher accuracy.

It is a control system figure of the blowby gas control device concerning Example 1 of the present invention. It is a front view of an engine. It is a longitudinal cross-sectional view of FIG. It is a graph which shows the relationship between the negative pressure of a PCV valve | bulb, and blow-by gas flow volume. It is a map which shows the relationship between an accelerator opening and a throttle valve opening. It is a time chart which shows the relationship between accumulation water content and engine cold operation. It is a flowchart which shows the example of the blowby gas recirculation | reflux process which CPU performs. It is a time chart explaining the moisture increase phenomenon of blow-by gas.

  Hereinafter, modes for carrying out the present invention will be described based on examples. In the figure, the vertical direction is the vertical direction, and the horizontal direction is the horizontal direction.

Embodiment 1 of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, the blow-by gas control device 1 for the engine E of this embodiment includes a throttle valve (intake flow control valve) 20, a downstream side passage (downstream side blow-by gas recirculation passage) 21, and an upstream side passage ( (Upstream blow-by gas recirculation passage) 22, intake flow rate control means 51, water content determination means 52, recirculation passage switching means 53, and the like.

The engine E is an in-line four-cylinder four-cycle gasoline engine. The engine E includes a cylinder head 2, a cylinder block 3, a crank chamber 4, an oil pan 5, and the like. A combustion chamber 6 is formed between the cylinder head 2 and the cylinder block 3.
The cylinder head 2 includes a cylinder head cover 7 that covers the top of the cylinder head 2, intake and exhaust ports 8 and 9 that communicate with the combustion chamber 6, a spark plug 10 that has a tip electrode facing the combustion chamber 6, An electronically controlled fuel injection valve 11 capable of directly injecting fuel into the cylinder head and a variable valve timing mechanism 12 disposed inside the cylinder head cover 7 are provided.

  The cylinder head cover 7 has an oil separator 13 connected to one end of the upstream passage 22. The oil separator 13 includes a plurality of baffle plates (not shown), the blow-by gas flowing from the crank chamber 4 collides with the baffle plates to attach the oil mist, and the oil mist is separated from the introduced blow-by gas. ing. The oil mist adhering to the baffle plate is made into droplets, and the oil that has become droplets falls into the oil pan 5. The blow-by gas from which the oil mist has been removed is led out to the upstream side passage 22. The intake and exhaust ports 8 and 9 are configured to be opened and closed by an intake valve 14 and an exhaust valve 15 that are driven up and down by intake and exhaust camshafts (not shown), respectively. The intake camshaft is provided with a cam angle sensor 41 such as an electromagnetic pickup in order to detect its rotational position.

An intake manifold 16 and an exhaust manifold 17 are connected to the intake and exhaust ports 8 and 9, respectively. An intake passage 19 is connected to the upstream side of the intake manifold 16 via a surge tank 18 having a predetermined volume. A throttle valve 20 and an air flow sensor 42 are provided in the intake passage 19. The throttle valve 20 is formed so that the flow passage area of the intake passage 19 can be changed, and includes a drive motor 23 that can drive the throttle valve 20, and a throttle body 24 that houses the throttle valve 20 and the drive motor 23. The throttle valve 20 controls the amount of intake air introduced into the combustion chamber 6 by adjusting the throttle opening by a drive motor 23 that receives an electric signal from an ECU (Electronic Control Unit) 50 described later. Since the other end of the upstream passage 22 is connected to a position upstream of the air flow sensor 42 installation position of the intake passage 19, the blow-by gas in the oil separator 13 is led out from the oil separator 13 and is sent by the upstream passage 22. The refrigerant is returned to a position upstream of the throttle valve 20. The downstream side of the exhaust manifold 17, are provided an air-fuel ratio sensor (O ₂ sensor) 44, an exhaust passage 26 through the catalyst 25 is connected.

  The variable valve timing mechanism 12 is provided at one end of the intake side camshaft, and the camshaft and the cam pulley (not shown) can be relatively rotated by hydraulic pressure to change the rotational phase of the camshaft relative to the crankshaft 30. Is formed. The hydraulic oil for the variable valve timing mechanism 12 is supplied from an oil pump (not shown) through an electromagnetic oil control valve (not shown). When an electric signal from the ECU 50 is input to the electromagnetic solenoid of the oil control valve, the flow rate and direction of the hydraulic oil are adjusted, and the opening / closing timing of the intake valve 14 is adjusted. Thereby, the three timings of the opening / closing timing of the intake valve 14 are the normal timing control, the slow closing timing control for changing the timing to the retard side from the normal timing, and the early closing timing control for changing the timing to the advance side from the normal timing. You can selectively switch to the characteristics.

  The cylinder block 3 can communicate with the four cylinders 27, the pistons 28 inserted into the cylinders 27, a water jacket (not shown) through which the cooling water of the engine E passes, the crank chamber 4 and the oil separator 13. A plurality of blow-by gas internal passages 29 to be connected are provided. The combustion chamber 6 is formed by the lower surface of the cylinder head 2, the cylinder 27, and the upper surface of the piston 28. The reciprocating motion of the piston 28 is converted into the rotational motion of the crankshaft 30. A water temperature sensor 45 that detects the cooling water temperature of the engine E is provided in the water jacket. The plurality of blow-by gas internal passages 29 are formed between the cylinder 27 and the water jacket so as to penetrate from the lower end to the upper end of the cylinder block 3 and pass the blow-by gas staying in the crank chamber 4 to the cylinder head 2 side. It is made possible.

  The crank chamber 4 includes a crankshaft 30, a crank angle sensor 46 that detects the rotation angle of the crankshaft 30, a PCV valve 31 that connects the inside of the crank chamber 4 and one end of the downstream passage 21, and the like. . The other end of the downstream passage 21 is connected to the surge tank 18. Thereby, the blow-by gas in the crank chamber 4 is led out from the crank chamber 4 and is returned to the downstream side position from the throttle valve 20 through the downstream side passage 21. An oil separator portion that can separate oil mist from blow-by gas may be provided at a connection portion between the inside of the crank chamber 4 and one end portion of the downstream passage 21.

  The PCV valve 31 is mounted at the middle position of the crank chamber 4 and is formed to be able to open and close the flow path of the downstream side passage 21. The PCV valve 31 maintains a closed state when the intake negative pressure (hereinafter referred to as negative pressure) acting on the downstream passage 21 is less than a first negative pressure set in advance, for example, less than 50 mmHg, and opens at the first negative pressure. When the first negative pressure and the second negative pressure, for example, 200 mmHg, are actuated, the opening degree is increased substantially in proportion to the negative pressure. When the negative pressure acting on the downstream passage 21 is equal to or higher than the second negative pressure, the PCV valve The maximum opening of 31 is maintained.

  As shown in FIG. 4, when the negative pressure in the surge tank 18 is less than the first negative pressure, the flow rate of the blow-by gas flowing in the PCV valve 31 is returned to the upstream position from the throttle valve 20 by the upstream passage 22. When the negative pressure in the surge tank 18 is equal to or higher than the first negative pressure and lower than the second negative pressure, the downstream side passage 21 returns to the downstream side position relative to the throttle valve 20 in proportion to the negative pressure and the upstream side passage When the negative pressure in the surge tank 18 is equal to or higher than the second negative pressure, the refrigerant is recirculated to the downstream position from the throttle valve 20 by the downstream passage 21. In the high negative pressure region, although the PCV valve 31 operates to the maximum opening, the intake amount of the engine E is reduced by the throttle valve 20, and the generated blow-by gas amount itself is reduced.

Here, the structure of the surge tank 18 will be described.
As shown in FIGS. 2 and 3, the surge tank 18 is formed long in the cylinder arrangement direction. The throttle body 24 is connected to the upper right end of the surge tank 18 in a front view, and the axis X of the throttle body 24 extends to the lower left end of the surge tank 18. The surge tank 18 is connected to an orthogonal wall portion 18a substantially orthogonal to the axis line X at a position below the axis line X and a lower end of the orthogonal wall portion 18a and bulges from the orthogonal wall portion 18a to the intake upstream side (upper right side). A portion 18b and the like are provided. The downstream passage 21 is connected to the lower right end portion of the surge tank 18, extends to the left along the lower wall portion of the surge tank 18, and has a lead-out portion 21 a for leading blow-by gas into the surge tank 18. It is formed at the lower left end.

  As a result, the intake air adjusted by the throttle valve 20 flows from the upper right side to the lower left side along the axis X as shown by the arrow in FIG. 3, and is guided to the lower wall portion and the bulging portion 18b to be a surge tank. 18 flows to the central portion of 18 and is supplied to each intake port 8 from this central portion. Further, the blow-by gas introduced into the surge tank 18 from the lead-out portion 21 a merges with the intake air toward the central portion of the surge tank 18. Therefore, the separation distance between the negative pressure zone generated immediately downstream of the throttle valve 20 and the lead-out portion 21a can be set large, and blow-by gas flowing in the surge tank 18 is negatively pressured by the orthogonal wall portion 18a and the bulging portion 18b. It can be guided in a direction away from the band.

  The oil pan 5 is installed in the lower part of the crank chamber 4 and is formed so as to be able to store engine oil. The engine oil is introduced into an oil pump provided outside the cylinder block 3, and after being pressurized, the engine oil and the valve timing such as the crankshaft 30 are passed through an oil gallery formed in the cylinder block 3. It is pumped to a mechanism part such as the variable mechanism 12.

Next, the ECU 50 will be described.
The ECU 50 includes a CPU, a ROM, a RAM, an I / F, and the like. The CPU controls the engine E by executing a control program stored in the ROM. The ROM includes a program executed by the CPU, an ignition timing set according to the operating state of the engine E, a fuel injection timing, a fuel injection amount, an opening / closing timing of the intake / exhaust valves 14 and 15, an accelerator opening and a throttle valve opening Information such as a correlation map, a determination condition of the accumulated water amount, a blow-by gas recirculation passage switching timing, and the like are stored. The RAM stores temporary data. The I / F detects a cam angle sensor 41, an air flow sensor 42, an accelerator opening sensor 43 that detects an operation amount with respect to an accelerator pedal (not shown), an air-fuel ratio sensor 44, a water temperature sensor 45, a crank angle sensor 46, and an outside air temperature. Detection results of the outside air temperature sensor 47 and the like are input, and the CPU can read these detection values. A control command from the CPU is output as an electrical signal to the spark plug 10, the fuel injection valve 11, the valve timing variable mechanism 12, the drive motor 23 of the throttle valve 20, and the like via the I / F.

As shown in FIG. 1, the ECU 50 is provided with an intake air flow rate control means 51, a water content determination means 52, a reflux passage switching means 53, and the like.
The intake flow rate control means 51 controls normal opening control for controlling the throttle valve 20 to an opening corresponding to the accelerator opening, and controls the throttle valve 20 to a lower opening side than the opening corresponding to the accelerator opening. 1 and 2nd low opening degree control are comprised so that execution is possible. The intake air flow rate control means 51 executes the first low opening degree control when the outside air temperature is, for example, −10 ° C. or lower.

  As shown in FIG. 5, the throttle valve opening increases in proportion to the increase in accelerator opening up to the accelerator opening α, and the opening characteristic A increases in proportion to the increase in accelerator opening. An opening characteristic A1 that regulates the throttle valve opening β1 above α1 and an opening that increases in proportion to an increase in the accelerator opening α2 up to the accelerator opening α2 and that regulates to the throttle valve opening β2 above the accelerator opening α2 It is controlled by three maps based on the characteristic A2. The intake flow rate control means 51 controls the throttle valve 20 so as to have an opening characteristic A during normal opening control, an opening characteristic A1 during first low opening control, and an opening characteristic A2 during second low opening control. I have control. In the opening characteristic A1, the throttle valve opening β1 is set to an opening that secures a first negative pressure at which the PCV valve 31 can be opened on the downstream side of the throttle valve 20, for example, a negative pressure of 50 mmHg. In the opening characteristic A2, the throttle valve opening β2 is set to an opening that secures a second negative pressure at which the PCV valve 31 has a maximum opening on the downstream side of the throttle valve 20, for example, a negative pressure of 200 mmHg.

  The moisture amount determination means 52 determines whether or not the accumulated moisture accumulated in the oil pan 5 has reached a predetermined accumulation allowable value FL. In the present embodiment, the accumulated moisture is condensed on the wall surface of the crank chamber 4 and the oil pan 5 when the engine temperature is lowered to near the dew point temperature, and the condensed moisture is transmitted along the wall surface to the engine oil inside the oil pan 5. The moisture accumulated inside is defined, and the accumulation allowable value FL is defined as the amount of accumulated moisture when the accumulated moisture starts to vaporize and the steam V is suddenly generated in the warm-up state of the engine E. Since the allowable accumulation value FL varies depending on external factors such as the environment and internal factors such as engine displacement, the accumulation allowable value FL and accumulated moisture start to vaporize in advance for the target engine E, and the steam V rapidly increases. The generated engine temperature (for example, the cooling water temperature is 70 ° C. or the oil temperature is 50 ° C.) is required.

  The moisture amount determination means 52 estimates the accumulated moisture amount F generated at each engine cold operation per period (period from ignition ON to ignition OFF). This accumulated moisture amount F can be calculated from the amount of blow-by gas generated in the engine E. That is, since the amount of blow-by gas generated in the engine E is determined by the burned air (intake amount), the accumulated moisture amount F can be calculated by detecting the intake intake amount after the ignition is turned on. Therefore, the total intake air amount is obtained by integrating the intake air amount detected during the cold engine operation detected by the air flow sensor 42, and the accumulated water amount F accumulated in the oil pan 5 is estimated based on the total intake air amount. ing. Further, the accumulated water amount F and the allowable accumulation value FL are converted into the intake air amount in advance, and it is estimated whether or not the accumulated water amount F (integrated value FTL) has reached the allowable storage value FL using the intake air amount as a parameter. Is also possible.

  The water content determination means 52 accumulates the accumulated water content F generated every time the engine cold operation is repeated every time the engine cold operation is repeated, stores the integrated value FTL, and the repetition of the engine cold operation is interrupted. When the second low opening degree control by the intake air flow rate control means 51 is released, the integrated value FTL is reset. In this embodiment, the engine cold operation starts the engine E at a low outside air temperature, for example, −10 ° C. or lower and the engine temperature is low, and the engine temperature starts to vaporize and the steam is generated suddenly. It is defined as an operation in which the engine E is stopped before a predetermined temperature, for example, the cooling water temperature reaches 70 ° C. The engine cold operation may be detected by using the oil temperature. In this case, the engine cold operation starts the engine E at an outside air temperature of −10 ° C. or lower and the engine temperature is low, and the oil temperature is 50 ° C. This is an operation in which the engine E is stopped before reaching.

  The recirculation passage switching means 53 determines that the integrated value FTL of the accumulated moisture amount F has reached the allowable accumulation value FL and the intake air when the engine E is in a high load operation state, for example, the throttle valve opening is fully open (100%). The flow rate control means 51 is configured to execute the second low opening degree control, and the valve timing variable mechanism 12 is configured to execute the late closing timing control.

As shown in FIG. 6, when the outside air temperature is −10 ° C. or lower, the ignition (Ig) is turned on at t1, the engine E is started, and the Ig is turned off before the cooling water temperature reaches 70 ° C. at t2. When the engine E is stopped, the engine cold operation is performed, so the accumulated moisture amount F1 is estimated and stored based on the total intake air amount during operation.
Next, if the engine E is started by turning on Ig at t3 at the same outside air temperature, and the engine E is stopped by turning off Ig before the cooling water temperature reaches 70 ° C. at t4, Since the operation is an inter-operation, the accumulated water amount F2 is estimated based on the total intake air amount during operation, and the integrated value FTL (F1 + F2) is cumulatively calculated and stored. In the period from t5 to t6, in the case of engine cold operation, the accumulated water amount F3 is estimated, and the integrated value FTL (F1 + F2 + F3) is cumulatively calculated and stored. When the engine cold operation continues, similarly, the cumulative calculation is continued until the integrated value FTL reaches the allowable storage value FL.

  Here, for example, during the period from t5 to t6, when it is determined that the integrated value FTL (F1 + F2 + ΔF) has reached the allowable storage value FL and the throttle valve opening is fully open, the second low opening by the intake flow rate control means 51 is determined. Start control. The second low opening degree control is canceled after a period in which all the accumulated moisture accumulated in the oil pan 5 is evaporated, for example, a cooling water temperature is 70 ° C. or more and an operation period of about 10 minutes is continued. In synchronization with the cancellation of the second low opening degree control, the stored integrated value FTL is reset and returned to the initial value zero. As a result, the amount of intake air can be suppressed, and the rise in cooling water temperature and oil temperature can be suppressed accordingly. Therefore, the sudden generation of accumulated moisture can be suppressed, and the blow-by gas containing a large amount of moisture can be passed through the PCV valve 31 through the downstream side passage. It is possible to return from 21 to the downstream side of the throttle valve 20. In addition, since the late closing timing control is executed at the same time, a desired negative pressure can be generated on the downstream side of the throttle valve 20 while suppressing a decrease in the intake air amount, so that a decrease in the output efficiency of the engine E can be suppressed.

  Also, during the period from t5 to t6, the engine cold operation is not repeated, so that the cooling water temperature reaches 70 ° C. or higher due to the so-called long-term operation and the operation period of about 10 minutes continues regardless of the throttle valve opening. When this is done, all of the accumulated moisture accumulated in the oil pan 5 evaporates, so the stored integrated value FTL is reset and returned to the initial value 0.

Next, the blow-by gas recirculation process of the blow-by gas control device 1 will be described based on the flowchart of FIG. Si (i = 1, 2,...) Indicates each step.
First, in S1, various data detected by each sensor are input and the accumulated value FTL stored continuously from the previous run is called. Next, it is determined whether or not Ig has been turned ON (S2). If Ig is turned on as a result of the determination in S2, the process proceeds to S3 to determine whether or not the cooling water temperature is less than 70 ° C.

  As a result of the determination in S3, when the cooling water temperature is lower than 70 ° C., the process proceeds to S4 to determine whether or not the outside air temperature is higher than −10 ° C. As a result of the determination in S4, when the outside air temperature is higher than −10 ° C., a map of the opening characteristic A that increases the throttle valve opening in proportion to the increase in the accelerator opening is selected (see FIG. 5), and is normally opened. After executing degree control, return.

As a result of the determination in S4, when the outside air temperature is −10 ° C. or lower, the routine proceeds to S6, where the intake air intake amount detected by the airflow sensor 42 is integrated, and the accumulated water amount F is estimated based on the integrated intake air amount. (S7). In this embodiment, a map in which the accumulated water amount F and the allowable storage value FL are converted into an intake air amount is prepared in advance, and the accumulated water amount F is estimated using this intake air amount as a parameter. The estimated accumulated water amount F is sequentially integrated to calculate an integrated value FTL. If there is an accumulated value FTL stored continuously from the previous run, the accumulated water amount F estimated this time is sequentially added to the previous accumulated value FTL to calculate the current accumulated value FTL. doing.
After the estimation of the accumulated water amount F, the process proceeds to S8, and the map of the opening characteristic A1 that increases in proportion to the increase of the accelerator opening to the accelerator opening α1 and is regulated to the throttle valve opening β1 at the accelerator opening α1 or more. Is selected (see FIG. 5), and the throttle valve 20 is controlled. After executing the first low opening degree control, the process returns.

  As a result of the determination in S3, if the cooling water temperature is 70 ° C. or higher, the process proceeds to S9, where it is determined whether or not the accumulated value FTL of the accumulated water amount F has exceeded the allowable storage value FL. In S9, the possibility of occurrence of the moisture increase phenomenon of the blow-by gas is determined by comparing the intake air amount according to the integrated value FTL and the intake air amount according to the accumulation allowable value FL.

  As a result of the determination in S9, if the integrated value FTL is greater than or equal to the allowable storage value FL, the process proceeds to S10, where it is determined whether or not the throttle valve 20 is in a high load operation state near the fully open state. By detecting a state in which the integrated value FTL is equal to or greater than the allowable storage value FL, a state in which the possibility of occurrence of a moisture increase phenomenon in blow-by gas is high is detected. If the integrated value FTL is less than the allowable storage value FL as a result of the determination in S9, the process proceeds to S4. By detecting a state in which the integrated value FTL is less than the allowable storage value FL, a state in which the possibility of occurrence of a moisture increase phenomenon in the blow-by gas is low is detected.

As a result of the determination in S10, when the throttle valve 20 is in a high load operation state near the fully open state, the process proceeds to S11 to determine whether or not the timer T for counting a predetermined time, for example, 10 minutes is set. In the normal opening degree control, when the accelerator opening degree is operated to the vicinity of the fully open position, the negative pressure is hardly generated on the downstream side of the throttle valve 20, so that the PCV valve 31 is kept closed and the blow-by gas is in the upstream side passage 22. Thus, the refrigerant is returned to the intake passage 19 on the upstream side of the throttle valve 20. As a result of the determination in S10, when the throttle valve 20 is not in the high load operation state near the full open, the process proceeds to S4.
If the timer T is activated as a result of the determination in S11, the process proceeds to S12, and a value obtained by subtracting 1 from the previous timer value T (i-1) is set as the current timer value T (i). If the timer T is not operating as a result of the determination in S11, the timer T is set (S16), and the process proceeds to S12.

After subtracting the timer value in S12, the process proceeds to S13 to determine whether or not the current timer value T (i) is zero. If the result of the determination in S13 is that the current timer value T (i) is not zero, the routine proceeds to S14, where the throttle valve is increased up to the accelerator opening α2 in proportion to the increase in the accelerator opening α2 and is greater than the accelerator opening α2. A map of the opening characteristic A2 that restricts to the degree β2 is selected (see FIG. 5), and the throttle valve 20 is controlled. In S14, the second low opening degree control and the delayed closing timing control by the variable valve timing mechanism 12 are executed, and then the process returns. Thereby, a negative pressure of 200 mmHg can be secured on the downstream side of the throttle valve 20, the PCV valve 31 can be opened and the blow-by gas can be recirculated through the downstream side passage 21.
If the current timer value T (i) is zero as a result of the determination in S13, the accumulated value FTL accumulated and stored is reset to zero (S15), and the process proceeds to S4.

As a result of the determination in S2, if Ig is turned off, the process proceeds to S17.
In S17, it is determined whether or not the state in which the cooling water temperature is 70 ° C. or higher continues for a predetermined time, for example, 10 minutes or longer before the Ig is turned off during traveling of the vehicle.
As a result of the determination in S17, when the state where the cooling water temperature is 70 ° C. or more continues for 10 minutes or more, the process proceeds to S18, where the accumulated value FTL accumulated and stored is reset to zero and the process ends. As a result of the determination in S17, if the state where the cooling water temperature is 70 ° C. or higher has not continued for 10 minutes or longer, the current integrated value FTL is stored and the process ends.

Next, the operation and effect of the blow-by gas control device 1 will be described.
In this blow-by gas control device 1, since the intake flow rate control means 51 can execute low opening degree control that generates a negative pressure downstream of the throttle valve 20 without causing structural changes such as formation of a hot water passage or an increase in the number of parts, The blow-by gas can be recirculated by the downstream side passage 21, and freezing of the throttle valve 20 can be suppressed. It is possible to determine whether or not the accumulated moisture accumulated in the oil pan 5 has reached the allowable accumulation value FL by the moisture amount determination means 52, and the possibility of occurrence of a moisture increase phenomenon of blow-by gas can be determined. . Further, when the recirculation passage switching means 53 is in an engine high load operation state in which there is a high possibility of occurrence of the moisture increase phenomenon of the blow-by gas and the negative pressure on the downstream side of the throttle valve 20 is small, the second low opening of the intake flow control means 51 is Since the degree control is executed, the low opening degree control period can be shortened, and the output efficiency reduction of the engine E due to the low opening degree control can be suppressed. Therefore, freezing due to moisture contained in the blow-by gas of the throttle valve 20 can be suppressed while maintaining the output efficiency of the engine E.

  The recirculation passage switching means 53 operates the second low opening degree control by the intake flow rate control means 51 when it is determined that the accumulated water amount F (integrated value FTL) has reached the allowable storage value FL and the throttle valve 20 is fully open. Therefore, the second low opening degree control period can be executed when there is a high possibility of occurrence of the moisture increase phenomenon of the blowby gas and no negative pressure downstream of the throttle valve 20 is generated. The engine output efficiency can be further suppressed from being reduced.

The recirculation passage switching means 53 operates the second low opening degree control by the intake flow rate control means 51 so as to generate a negative pressure that fully opens the PCV valve 31 on the downstream side of the throttle valve 20. In addition, excessive negative pressure exceeding the supply capacity of the PCV valve 31 can be prevented, the intake amount of the engine E can be secured, and a decrease in engine output efficiency can be further suppressed.
The recirculation passage switching means 53 accumulates in the oil pan 5 in order to cancel the second low opening degree control by the intake flow rate control means 51 when the duration time of the second low opening degree control reaches a predetermined duration time. The second low opening degree control of the intake flow rate control means 51 can be canceled in synchronization with the completion of the vaporization of the accumulated water, the second low opening degree control period can be made the shortest time, and the engine output efficiency reduction is further suppressed. be able to.

  The water content determination means 52 estimates the accumulated water content F generated during engine cold operation in which the engine E is started at a low outside air temperature and a low engine temperature and the engine E is stopped before the cooling water temperature reaches a predetermined temperature. Every time this engine cold operation is repeated continuously, the accumulated water amount F generated during the engine cold operation is integrated and the integrated value FTL is stored, so that the accumulated value FTL is stored in the oil pan 5 in one engine cold operation. The accumulated value FTL of the accumulated amount of accumulated water F can be accurately grasped, and the second low opening degree control can be executed with high accuracy.

Since the water content determination means 52 resets the integrated value FTL when the engine cold operation is stopped, the integrated value FTL of the accumulated water content T accumulated in the oil pan 5 can be grasped more accurately. 2. Low-opening control can be executed with higher accuracy.
When the second low opening degree control by the intake air flow rate control means 51 is canceled, the moisture amount determination means 52 resets the accumulated value FTL so that the accumulated value FTL of the accumulated moisture amount F accumulated in the oil pan 5 is obtained. Thus, the second low opening degree control can be executed with higher accuracy.

Next, a modification in which the above embodiment is partially changed will be described.
1) In the above-described embodiment, the example in which the engine temperature is detected by the cooling water temperature has been described. However, it is sufficient that at least the engine warm-up state can be detected, and the engine temperature may be detected by the oil temperature. In the above embodiment, the accumulated water vaporization period is about 10 minutes from the time when the engine cooling water temperature is 70 ° C. (oil temperature 50 ° C.). However, external factors such as the environment, engine displacement, etc. The temperature and duration can be adjusted according to the internal factors.

2) In the above-described embodiment, the example in which the second low opening degree control release condition has been described that the duration of 10 minutes from the start of the second low opening degree control is elapsed. After starting the degree control, it is also possible to set the release condition of the second low opening degree control that the engine temperature, for example, the coolant temperature of 90 ° C. has been reached.

3) In the above-described embodiment, the example in which the interruption of repeated engine cold operation is determined by continuing the operation state of the cooling water temperature of 70 ° C. or higher for 10 minutes has been described. However, the engine temperature (cooling water temperature or oil temperature) is described. ) May be used to determine whether the engine cold operation is repeated.
4) In addition, those skilled in the art can implement the present invention in various forms added with various modifications without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

  In the engine blow-by gas control device, when it is determined that the amount of accumulated water has reached the allowable accumulation value and the throttle valve opening is in a high load state, the throttle valve is operated more than the opening corresponding to the accelerator opening. By controlling to the low opening side, freezing of the throttle valve can be suppressed while maintaining the engine output efficiency.

1 Blow-by gas control device 4 Crank chamber 5 Oil pan 20 Throttle valve 21 Downstream passage 22 Upstream passage 31 PCV valve 43 Accelerator opening sensor 45 Water temperature sensor 50 ECU
51 Intake flow rate control means 52 Moisture content determination means 53 Reflux passage switching means E Engines F, F1, Accumulated water content F2, F3
FL allowable accumulation value FTL integrated value

Claims (7)

An intake air flow rate control valve capable of adjusting the intake air amount supplied to the engine by an electric signal linked to the operation of the accelerator pedal, an upstream side blowby gas recirculation passage communicating the upstream side of the intake air flow rate control valve and the crank chamber, In an engine blow-by gas control device comprising a downstream blow-by gas recirculation passage communicating the downstream side of the intake flow control valve and the crank chamber, and a PCV valve provided in the middle of the downstream blow-by gas recirculation passage,
Normal opening control for controlling the intake flow control valve to an opening corresponding to the operation of the accelerator pedal and low opening control for controlling the intake flow control valve to a lower opening side than the opening corresponding to the operation of the accelerator pedal Intake air flow rate control means capable of performing
A moisture amount determination means for determining whether or not the accumulated moisture accumulated in the oil pan has reached a predetermined amount;
An engine comprising: a recirculation passage switching means for causing the intake air flow control means to perform low opening degree control when it is determined that the accumulated water amount has reached a predetermined value and the engine is in a high load operation state. Blow-by gas control device.   The recirculation passage switching means operates the low opening degree control by the intake flow rate control means when it is determined that the accumulated water amount has reached a predetermined value and the intake flow rate control valve is fully open. 2. A blow-by gas control device for an engine according to 1.   2. The recirculation passage switching means operates low opening degree control by the intake flow rate control means so as to generate a negative pressure at which the PCV valve is fully opened downstream of the intake flow rate control valve. Or the blow-by gas control apparatus of the engine of 2.   The recirculation passage switching means cancels the low opening degree control by the intake flow rate control means when at least one of the duration of the low opening degree control and the engine temperature reaches a set value. The blow-by gas control device for an engine according to any one of 1 to 3.   The moisture amount determination means estimates an accumulated moisture amount generated during engine cold operation in which the engine is started at a low outside air temperature and a low engine temperature and the engine is stopped before the engine temperature reaches a predetermined temperature. The engine blow-by according to any one of claims 1 to 4, wherein the accumulated value is stored by accumulating the accumulated water amount generated during the engine cold operation every time the cold operation is continuously repeated. Gas control device.   6. The engine blow-by gas control device according to claim 5, wherein the moisture amount determination unit resets the integrated value when the repetition of the engine cold operation is interrupted. 7. The engine blow-by gas control device according to claim 5, wherein the moisture amount determination unit resets the integrated value when the low opening degree control by the intake flow rate control unit is released.