JP5664426B2 - Crankcase ventilation device for internal combustion engine - Google Patents

Description

  The present invention relates to a crankcase ventilation device for an internal combustion engine in which blow-by gas in the crankcase is discharged into an intake passage.

  There is a crankcase ventilation device for an internal combustion engine provided with an introduction passage for guiding intake air from the intake passage into the crankcase and a discharge passage for discharging blowby gas in the crankcase to the intake passage. A crankcase ventilation device for such an internal combustion engine that opens and closes an introduction passage and a discharge passage using a counterweight provided on a crankshaft is known (for example, see Patent Document 1). In addition, there are Patent Documents 2 to 4 as prior art documents related to the present invention.

JP 2009-293549 A JP-A-7-145717 JP-A-9-68028 JP 2010-90869 A

  If blow-by gas accumulates in the crankcase, adverse effects can occur. For this reason, ventilation in the crankcase such as discharge of blow-by gas and introduction of fresh air is necessary. In the crankcase ventilation device of Patent Document 1, ventilation in the crankcase is performed by using pressure change accompanying the vertical movement of the piston and rotational movement of the counterweight. On the other hand, ventilation in the crankcase can also occur due to a pressure difference from the intake passage. Further, the pressure in the intake passage tends to change according to the load state of the internal combustion engine. However, in the crankcase ventilation device of Patent Document 1, the load of the internal combustion engine is not reflected in the opening / closing timing of the introduction passage and the discharge passage. For this reason, when the pressure difference between the intake passage and the inside of the crankcase is large, there is a possibility that the discharge amount of blow-by gas increases excessively. In this case, the amount of oil carried away in the crankcase by blow-by gas also increases excessively. On the other hand, when the pressure difference between the intake passage and the crankcase is small, the blow-by gas may not be sufficiently ventilated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a crankcase ventilation device for an internal combustion engine that can appropriately adjust the ventilation performance in the crankcase such as introduction of intake air and discharge of blow-by gas according to the load of the internal combustion engine. And

The crankcase ventilation device for an internal combustion engine according to the present invention includes a first ventilation passage connecting the inside of the crankcase of the internal combustion engine and an intake passage, a position upstream of the first ventilation passage of the intake passage, and the inside of the crankcase. A second ventilation passage that connects to the crankcase, and the crankcase changes such that the internal pressure is higher than the step of rising in the step of lowering the piston as the at least one piston moves up and down. A crankcase ventilation apparatus for an internal combustion engine, provided in the first ventilation passage, and provided in the second ventilation passage, and a first regulating valve that operates to close and open the first ventilation passage, a second control valve operable to close and open the second ventilation passage, the first ventilating passage in the process of the piston is lowered in the internal combustion engine, wherein the piston to rise Valve control means for controlling the operation of the first adjustment valve and the second adjustment valve so that the second ventilation passages are opened in the process, respectively, and the valve control means The operation timing of the first adjustment valve and the second adjustment valve is changed according to the load (Claim 1).

  According to this crankcase ventilation device for an internal combustion engine, the first ventilation passage is opened when the piston is raised, and the second ventilation passage is opened when the piston is lowered. Accordingly, blow-by gas can be discharged and intake air can be discharged through the first ventilation passage and the second ventilation passage using the pressure change in the crankcase. Further, the operation timings of the first and second regulating valves vary according to the load of the internal combustion engine. Since the first ventilation passage and the second ventilation passage are opened and closed by the first adjustment valve and the second adjustment valve, the opening and closing timings of the first ventilation passage and the second ventilation passage are changed according to the load of the internal combustion engine. Can do. That is, the load of the internal combustion engine can be reflected in the opening / closing timing of these passages. As a result, the ventilation of the crankcase, such as the introduction of intake air and the discharge of blow-by gas, can be appropriately adjusted according to the load of the internal combustion engine.

  In one aspect of the crankcase ventilation device for an internal combustion engine according to the present invention, the valve control means includes a first ventilation period from when the first ventilation passage is opened to when the first ventilation passage is closed according to a load of the internal combustion engine, and The second ventilation period from when the second ventilation passage is opened to when the second ventilation passage is closed is longer during the high load of the internal combustion engine than during the low / medium load of the internal combustion engine. The operation timing of the first adjustment valve and the second adjustment valve may be changed (Claim 2). The pressure difference between the intake passage and the crankcase tends to be large when the internal combustion engine is at low and medium loads and small at high loads. In this case, the first ventilation period and the second ventilation period are long at the time of high load of the internal combustion engine and are short at the time of low and medium load. Thereby, the ventilation period in a crankcase can be shortened when the pressure difference with an intake passage is large, and can be lengthened when it is small. That is, it is possible to reduce the blow-by gas discharge amount when the pressure difference with the intake passage is large, while ensuring a sufficient intake amount when the pressure difference with the intake passage is small.

In an aspect in which the ventilation period is long when the internal combustion engine is at a high load, the valve control unit is configured to perform the first ventilation period after the top dead center when the internal combustion engine is at a low to medium load according to the load of the internal combustion engine. The period from the bottom dead center to the position after the top dead center is adopted as the second ventilation period, while the period from the bottom dead center to the position after the bottom dead center is adopted. At the time of load, from the time after the bottom dead center as the first ventilation period and earlier than the start time of the first ventilation period at the time of low to medium load of the internal combustion engine until the piston is located at the bottom dead center This period is the second ventilation period after the bottom dead center, and the piston is positioned at the top dead center from a time earlier than the start time of the second ventilation period when the internal combustion engine is under low to medium load. The period, as adopted respectively, may be changed operation timing of the first adjusting valve and the second adjustment valve (claim 3). In this case, the first ventilation period and the second ventilation period are provided based on the bottom dead center and the top dead center at which the pressure fluctuation is maximized. For this reason, it is possible to more reliably perform the reduction of the blow-by gas discharge amount when the pressure difference between the intake passage and the intake passage is large, and ensure the intake amount when the pressure difference is small.

  Any method may be used to determine the load on the internal combustion engine. For example, in one aspect of the crankcase ventilation apparatus for an internal combustion engine of the present invention, the first ventilation passage is downstream of the throttle valve of the intake passage, and the second ventilation passage is upstream of the throttle valve of the intake passage. And the valve control means may determine the load of the internal combustion engine based on the opening degree of the throttle valve.

  As described above, according to the present invention, the opening / closing timings of the first ventilation passage and the second ventilation passage can be changed in accordance with the load of the internal combustion engine. The load of the engine can be reflected. As a result, the ventilation of the crankcase, such as the introduction of intake air and the discharge of blow-by gas, can be appropriately adjusted according to the load of the internal combustion engine.

The figure which showed typically the principal part of the internal combustion engine to which the crankcase ventilation apparatus which concerns on one form of this invention was applied. The figure for demonstrating the time when the 1st regulating valve at the time of the low and medium load of an internal combustion engine and a 2nd regulating valve operate | move. The figure which shows the relationship between the change of the crank angle and the change of the pressure in a crankcase when an internal combustion engine is a low and medium load. The figure for demonstrating the time when the 1st adjustment valve at the time of high load of an internal combustion engine and a 2nd adjustment valve operate | move. The figure which shows the relationship between the change of the crank angle and the change of the pressure in a crankcase when an internal combustion engine is a low and medium load. The figure which shows an example of the flowchart of the adjustment valve control routine which ECU performs in order to control operation | movement of a 1st adjustment valve or a 2nd adjustment valve.

  FIG. 1 is a diagram schematically showing a main part of an internal combustion engine to which a crankcase ventilation device according to one embodiment of the present invention is applied. An internal combustion engine (hereinafter sometimes referred to as an engine) 1 is mounted on a vehicle as a driving power source. As shown in FIG. 1, the internal combustion engine 1 has a cylinder block 3 in which a plurality of cylinders 2 (only one is shown in FIG. 1) is formed, and an intake port 4 and an exhaust port 5 are formed for each cylinder 2. And a cylinder head 6. In each cylinder 2, a piston 7 is inserted so as to be able to reciprocate, and a fuel chamber 8 is formed by the piston 7, the side surface of the cylinder 2, and the cylinder head 6.

  A crankcase 10 is provided below the cylinder block 3. An oil pan 11 is provided below the crankcase 10. Oil 12 is stored in the oil pan 11. A crankshaft 13 is accommodated in the crankcase 10. The crankshaft 13 is connected to the piston 7 via a connecting rod 14.

  An intake passage 15 is connected to the intake port 4, and an exhaust passage 16 is connected to the exhaust port 5. A throttle valve 17 is provided in the intake passage 15. The amount of intake air in the intake passage 15 is adjusted by the throttle valve 17. Further, the intake passage 15 is provided with a blow-by gas recirculation passage 20 as a first ventilation passage and a ventilation introduction passage 21 as a second ventilation passage. The blow-by gas recirculation passage 20 is provided at a position downstream of the throttle valve 17 in the intake passage 15 and connects the intake passage 15 and the inside of the crankcase 10. The ventilation introduction passage 21 is provided at a position upstream of the throttle valve 17 in the intake passage 15 and connects the intake passage 15 and the inside of the crankcase 10.

  The blow-by gas recirculation passage 20 is provided with a first adjustment valve 23, and the ventilation introduction passage 21 is provided with a second adjustment valve 24. The first regulating valve 23 operates to close and open the blow-by gas recirculation passage 20. Similarly, the second regulating valve 24 operates to close and open the ventilation introduction passage 21. The flow rates of the blow-by gas recirculation passage 20 and the ventilation introduction passage 21 are adjusted by the operation of the first adjustment valve 23 or the second adjustment valve 24, respectively. Moreover, the 1st adjustment valve 23 or the 2nd adjustment valve 24 is comprised as a known electromagnetic valve by which operation | movement is controlled using an electromagnet. The operation of the first adjustment valve 23 or the second adjustment valve 24 is controlled by an engine control unit (ECU) 25.

  The ECU 25 is a known computer unit that is configured as a computer including a microprocessor and peripheral devices such as a RAM and a ROM necessary for its operation, and controls the operating state of the engine 1. The ECU 25 also outputs output signals from various sensors such as a throttle valve opening sensor (not shown) that detects the opening of the throttle valve 17 or an air flow meter (not shown) that detects the intake air amount of the intake passage 15. Referring to, the control required for the internal combustion engine 1 is executed. As an example of various sensors, an output signal from a crank angle sensor 28 that detects the crank angle of the crankshaft 13 is input to the ECU 25. The ECU 25 refers to the output signal of the crank angle sensor 28 and controls, for example, the injection timing of the fuel injection valve 29 and the like. Further, the ECU 25 controls the operations of the first adjustment valve 23 and the second adjustment valve 24 with reference to the output signal of the crank angle sensor 28.

  Based on the position of the piston 7, the ECU 25 operates the first adjustment valve 23 at the first adjustment valve crank angle and the second adjustment valve 24 at the second adjustment valve crank angle. The ECU 25 also adjusts the crank angle for the first adjustment valve and the crank angle for the second adjustment valve so that the opening / closing timing of the blow-by gas recirculation passage 20 and the ventilation introduction passage 21 changes according to the operating state of the internal combustion engine 1. To change. Hereinafter, the crank angle for the first adjustment valve and the crank angle for the second adjustment valve will be described with reference to FIGS.

  FIG. 2 is a diagram for explaining the timing when the first regulating valve 23 and the second regulating valve 24 operate when the internal combustion engine is under a low / medium load. The circle in FIG. 2 corresponds to a change in the crank angle (the position of the piston 7). That is, the upper contact point between the vertical axis and the circle in FIG. 2 corresponds to the top dead center (TDC) of the reciprocating motion of the piston, and the lower contact point corresponds to the bottom dead center (BDC). The first adjustment valve crank angle HA1 includes a discharge start crank angle HS1 that operates so that the first adjustment valve 23 opens the blow-by gas recirculation passage 20, and a discharge end crank that operates so as to close the blow-by gas recirculation passage 20. It is constituted by a corner HE1. As shown in FIG. 2, BDC is used as a reference for the first adjusting valve crank angle HA1. Then, the position before BDC is used as the discharge start crank angle HS1 and the position after BDC is used as the discharge end crank angle HE1 so as to sandwich the BDC. On the other hand, the crank angle DA1 for the second adjustment valve includes an introduction start crank angle DS1 that operates so that the second adjustment valve opens the ventilation introduction passage 21, and an introduction end crank angle that operates so as to close the ventilation introduction passage 21. It is constituted by DE1. As shown in FIG. 2, TDC is used as a reference for the second control valve crank angle DA1. In order to sandwich the TDC, the position before the TDC is used as the introduction start crank angle DS1, and the position after the TDC is used as the introduction end crank angle DE1.

  The blow-by gas recirculation passage 20 is opened when the internal combustion engine 1 is at a low to medium load when the piston 7 is positioned at the discharge start crank angle HS1 and closed when the piston 7 is positioned at the discharge end crank angle HE1. A right oblique line in FIG. 2 indicates a first ventilation period 30 from when the blow-by gas recirculation passage 20 is opened to when it is closed. Similarly, the ventilation introduction passage 21 is opened when the piston 7 is located at the introduction start crank angle DS1, and is closed when the piston 7 is located at the introduction end crank angle DE1. 2 indicates a second ventilation period 31 from when the ventilation introduction passage 21 is opened to when it is closed. As shown in FIG. 2, only the blow-by gas recirculation passage 20 is opened during the first ventilation period 30, and only the ventilation introduction passage 21 is opened during the second ventilation period 31.

  FIG. 3 is a diagram illustrating a relationship between a change in the crank angle and a change in the pressure in the crankcase 10 when the internal combustion engine 1 has a low and medium load. The horizontal axis in FIG. 3 indicates the crank angle, and the vertical axis indicates the pressure in the crankcase 10. In the crankcase 10, the pressure changes as the piston 7 reciprocates. As shown in FIG. 3, this pressure tends to change so that the positive pressure is highest at BDC and the negative pressure is highest at TDC. 3 indicates a discharge period 32 during which blow-by gas is discharged from the crankcase 10, and a left diagonal line indicates an introduction period 33 during which intake air is introduced into the crankcase 10. As shown in FIG. 3, the discharge start crank angle HS1 and the discharge end crank angle HE1 are set so that the period during which the pressure in the crankcase 10 is a positive pressure equal to or greater than a certain value corresponds to the first ventilation period 30. Yes. Further, the introduction start crank angle DS1 and the introduction end crank angle DE1 are set so that the period in which the pressure in the crankcase 10 is a negative pressure equal to or greater than a certain value corresponds to the second ventilation period 31. Since the first ventilation period 30 corresponds to the positive pressure and the second ventilation period 31 corresponds to the negative pressure, respectively, the exhaust period 32 and the first ventilation period 30 correspond to the introduction period when the internal combustion engine has a low and medium load. 33 and the second ventilation period 31 coincide with each other. The positive pressure above a certain value and the negative pressure above a certain value are not limited to the values shown in FIG.

  On the other hand, FIG. 4 is a diagram for explaining the timing when the first regulating valve 23 and the second regulating valve 24 operate when the internal combustion engine 1 is under a high load. The circle in FIG. 4 corresponds to the change in the crank angle, as in FIG. As shown in FIG. 4, when the internal combustion engine 1 is at a high load, the first adjustment valve crank angle is such that the first ventilation period 30 and the second ventilation period 31 start earlier and become longer than at the time of low to medium load. HA2 and the second adjustment valve crank angle DA2 are used. Specifically, the position immediately after TDC, which is earlier than the discharge start crank angle HS1 when the internal combustion engine 1 is at a high load, is set as the discharge start crank angle HS2 when the internal combustion engine 1 is at a high load. As the angle HE2, the position of the BDC that is earlier than the discharge end crank angle HE1 at the time of low / medium load is used. Similarly, the position immediately after the BDC, which is earlier than the introduction start crank angle DS1 when the internal combustion engine 1 is under a high load, as the introduction start crank angle DS2 when the internal combustion engine 1 is under a high load, is the introduction end crank angle DE2 when the internal combustion engine 1 is under a high load. As a result, the position of the TDC that is earlier than the introduction end crank angle DE1 at the time of low to medium load is used.

  FIG. 5 is a diagram showing the relationship between the change in the crank angle and the change in the pressure in the crankcase 10 when the internal combustion engine 1 is under a high load. Similarly to FIG. 3, the horizontal axis in FIG. 5 represents the crank angle, and the vertical axis represents the pressure in the crankcase 10. Even when the internal combustion engine 1 is heavily loaded, the pressure change in the crankcase 10 shows the same tendency as in FIG. Similarly to FIG. 3, the right oblique line in FIG. 5 corresponds to the discharge period 32, and the left oblique line corresponds to the introduction period 33. As shown in FIG. 5, the period during which the pressure in the crankcase 10 is positive in the step of lowering the piston 7 corresponds to the discharge period 32, and the period during which the negative pressure is negative corresponds to the introduction period 33. Further, a period in which the positive pressure in the step of raising the piston 7 corresponds to the discharge period 32, and a period in which the negative pressure becomes negative corresponds to the introduction period 33.

  In FIG. 5, the first ventilation period 30 is indicated by a one-dot chain line, and the second ventilation period 31 is indicated by a solid line. As described above, the first ventilation period 30 substantially corresponds to the entire period of the descending process, and the second ventilation period 31 substantially corresponds to the entire period of the ascending process. Therefore, the positive pressure period of the first ventilation period 30 and the positive pressure period of the second ventilation period 31 are the discharge period 32, and the negative pressure period of the first ventilation period 30 and the negative pressure period of the second ventilation period 31 are. Each corresponds to the introduction period 33. That is, when the internal combustion engine 1 is under a high load, the blow-by gas recirculation passage 20 and the ventilation introduction passage 21 are used for both discharge of blow-by gas and introduction of intake air in accordance with a pressure change in the crankcase 10. Strictly speaking, there is a slight time interval between the first ventilation period 30 and the second ventilation period 31, and therefore there may be a period in which neither blow-by gas is discharged nor intake is introduced. Illustration is omitted.

  Next, a process executed by the ECU 25 to control the operation of the first adjustment valve 23 or the second adjustment valve 24 will be described. FIG. 6 is a diagram illustrating an example of a flowchart of an adjustment valve control routine executed by the ECU 25 to control the operation of the first adjustment valve 23 or the second adjustment valve 24. The control routine of FIG. 6 is repeatedly executed at a predetermined cycle during the operation of the internal combustion engine 1. The ECU 25 functions as the valve control means of the present invention by executing the control routine of FIG.

  In the control routine of FIG. 6, the ECU 25 first obtains the opening degree of the throttle valve 17 with reference to the output signal from the throttle valve opening degree sensor in step S11. In subsequent step S12, the ECU 25 determines whether or not the operating state of the internal combustion engine 1 is a high load. For this determination, the opening degree of the throttle valve 17 acquired in step S11 is used, and the ECU 25 determines whether or not the engine is in a high load state based on whether or not the opening degree exceeds a predetermined value. If the determination result in step S12 is a positive result, that is, if the opening degree of the throttle valve 17 exceeds a predetermined value, the ECU 25 determines that the load is high and proceeds to step S15. On the other hand, if the determination result in step S12 is negative, that is, if the opening degree of the throttle valve 17 is equal to or less than a predetermined value, the ECU 25 determines that the load is not high (low and medium load), and step S13. Proceed to

  In step S13, the ECU 25 refers to the output signal from the crank angle sensor 28, and the crank angle of the crankshaft 13 is a predetermined crank for low and medium loads that operates the first adjustment valve 23 and the second adjustment valve 24. Judge whether it is a corner. This determination is performed as follows as an example. First, the ECU 25 uses the first adjustment valve crank angle HA1 and the second adjustment valve crank angle DA1 as a predetermined crank angle for low and medium loads. In step S13, the ECU 25 refers to the output signal of the crank angle sensor 28 and determines whether or not the current crank angle corresponds to the first adjustment valve crank angle HA1 or the second adjustment valve crank angle DA1. to decide. Specifically, the ECU 25 determines whether or not the current crank angle corresponds to the discharge start crank angle HS1 or the discharge end crank angle HE1, or the introduction start crank angle DS1 or the introduction end crank angle DE1, respectively. If this determination is a negative result, that is, if the current crank angle does not correspond to either the first adjustment valve crank angle HA1 or the second adjustment valve crank angle DA1, the ECU 25 executes the current routine. Exit. On the other hand, if the determination in step S13 is a positive result, that is, the current crank angle corresponds to either the discharge start crank angle HS1 or the discharge end crank angle HE1, or the introduction start crank angle DS1 or the introduction end crank angle DE1. In that case, the ECU 25 proceeds to step S14.

  On the other hand, in step S15, the ECU 25 refers to the output signal from the crank angle sensor 28, and the crank angle of the crankshaft 13 is a predetermined for high load when the first adjusting valve 23 and the second adjusting valve 24 are operated. Judge whether the crank angle. This determination is performed as follows as an example. First, the ECU 25 uses the first adjustment valve crank angle HA2 and the second adjustment valve crank angle DA2 at the time of high load as the predetermined crank angle at the time of high load. In step S15, the ECU 25 refers to the output signal of the crank angle sensor 28 and determines whether or not the current crank angle corresponds to the first adjustment valve crank angle HA2 or the second adjustment valve crank angle DA2. to decide. Specifically, the ECU 25 determines whether or not the current crank angle corresponds to the discharge start crank angle HS2 or the discharge end crank angle HE2, or the introduction start crank angle DS2 or the introduction end crank angle DE2, respectively. If this determination is negative, that is, if the current crank angle does not correspond to either the first adjustment valve crank angle HA2 or the second adjustment valve crank angle DA2, the ECU 15 performs the current routine. Exit. On the other hand, if the determination in step S15 is a positive result, that is, the current crank angle corresponds to either the discharge start crank angle HS2 or the discharge end crank angle HE2, or the introduction start crank angle DS2 or the introduction end crank angle DE2. In that case, the ECU 25 proceeds to step S14.

  In step S14, the ECU 25 operates the first adjustment valve 23 and the second adjustment valve 24 based on the result of step S13 or step S15. Specifically, this operation is executed as follows. First, when it is determined in step S13 or step S15 that the current crank angle corresponds to the discharge start crank angle HS1, HS2, the ECU 25 operates the first adjustment valve 23 so that the blow-by gas recirculation passage 20 is opened. Let On the other hand, when the ECU 25 determines in step S13 or step S15 that the current crank angle corresponds to the discharge end crank angles HE1 and HE2, the ECU 25 operates the first adjustment valve 23 so that the blow-by gas recirculation passage 20 is closed. Let When the ECU 25 determines that the current crank angle corresponds to the introduction start crank angle DS1, DS2 in step S13 or step S15, the ECU 25 operates the second adjustment valve 24 so that the ventilation introduction passage 21 is opened. . On the other hand, if the ECU 25 determines in step S13 or step S15 that the current crank angle corresponds to the introduction end crank angle DE1, DE2, the ECU 25 operates the second adjustment valve 24 so that the ventilation introduction passage 21 is closed. . In step S14, the ECU 25 operates the first adjustment valve 23 and the second adjustment valve 24 in this way, and ends the current routine.

  When the internal combustion engine 1 has a low and medium load, a large negative pressure is generated downstream of the throttle valve 17. Since the blow-by gas recirculation passage 20 is connected downstream of the throttle valve 17, the pressure difference between the intake passage 15 side and the crankcase 10 side is large. According to this embodiment, when the internal combustion engine 1 is at low and medium loads, the discharge period 32 during which blow-by gas is discharged from the crankcase 10 is limited to the first ventilation period 30 in which the blow-by gas recirculation passage 20 is opened. Moreover, the 1st ventilation period 30 is set to BDC vicinity with a high positive pressure. For this reason, while realizing sufficient discharge of blow-by gas, it is possible to reduce the discharge amount of blow-by gas in order to suppress unnecessary discharge. As a result, oil removal associated with blow-by gas discharge can be reduced. On the other hand, the introduction period 33 during which intake air is introduced into the crankcase 10 is limited to the second ventilation period 31 in which the ventilation introduction passage 21 is opened. Further, the second ventilation period 31 is set in the vicinity of the TDC having a high negative pressure. Thereby, the introduction of intake air can be reduced so that the introduction of unnecessary intake air into the crankcase 10 is suppressed while the intake air is sufficiently introduced.

  On the other hand, when the internal combustion engine 1 is under a high load, since the negative pressure is small both upstream and downstream of the throttle valve 17, there is a possibility that ventilation such as discharge of blow-by gas in the crankcase 10 and introduction of intake air may not be performed sufficiently. is there. In this embodiment, when the internal combustion engine 1 is at a high load, the first ventilation period 30 corresponds to almost the entire period of the process in which the piston 7 descends, and the second ventilation period 31 corresponds to almost the entire period of the process in which the piston 7 rises. doing. These periods start earlier than the first ventilation period 30 and the second ventilation period 31 at the time of low and medium loads, and are longer. That is, at the time of high load, the first ventilation period 30 and the second ventilation period 31 are started earlier than at the time of low to medium load, and a long period is secured. Thereby, since the discharge period 32 and the introductory period 33 can be extended at the time of the high load where a ventilation rate falls, a ventilation rate can be improved. That is, according to this embodiment, since the first ventilation period 30 and the second ventilation period 31 can be changed according to the load of the internal combustion engine 1, the load of the internal combustion engine 1 is applied during the discharge period 32 and the introduction period 33. Can be reflected. Thereby, the ventilation rate in the crankcase 10 can be appropriately adjusted according to the load of the internal combustion engine 1.

  This invention is not limited to the above-mentioned form, It can implement with a various form within the range of the summary of this invention. For example, the present invention can be applied to a single cylinder engine or a diesel engine. Therefore, the throttle valve may be omitted. In this case, the second ventilation passage only needs to be provided upstream of the first ventilation passage in the intake passage.

  Further, in the above-described form, the load of the internal combustion engine is determined by the opening degree of the throttle valve, but it is not limited to such form. For example, the load of the internal combustion engine may be determined based on the intake air amount using an air flow meter. Alternatively, the rotational speed and torque of the internal combustion engine may be used for determining the load.

  Further, the first ventilation period and the second ventilation period are not limited to the above-described forms. The first ventilation period and the second ventilation period are periods based on the top dead center and the bottom dead center, and may be a period that is short when the internal combustion engine is at low and medium loads and long at a high load.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 10 Crankcase 15 Intake passage 17 Throttle valve 20 Blow-by gas recirculation passage 21 Ventilation introduction passage 23 1st adjustment valve 24 2nd adjustment valve 25 Engine control unit (valve control means)
30 First ventilation period 31 Second ventilation period

Claims (4)

A first ventilation passage that connects the inside of the crankcase of the internal combustion engine and the intake passage, and a second ventilation passage that connects a position upstream of the first ventilation passage of the intake passage and the inside of the crankcase. The crankcase is a crankcase ventilation device for an internal combustion engine that changes so that the internal pressure becomes higher than the step of raising in the step of lowering the piston as the at least one piston moves up and down ,
A first regulating valve provided in the first ventilation passage and operable to close and open the first ventilation passage; and provided in the second ventilation passage and closed and opened in the second ventilation passage. a second control valve which operates such that said said piston of the internal combustion engine is the first ventilating passage in the process of descending, the second ventilating passage in the process of the piston is increased is opened, respectively, the first A valve control means for controlling the operation of the regulating valve and the second regulating valve,
The crankcase ventilation device for an internal combustion engine, wherein the valve control means changes an operation timing of the first adjustment valve and the second adjustment valve in accordance with a load of the internal combustion engine.   According to the load of the internal combustion engine, the valve control means includes a first ventilation period from when the first ventilation passage is opened until it is closed, and after the second ventilation passage is opened until it is closed. Therefore, the operation timings of the first adjustment valve and the second adjustment valve are set so that both of the second ventilation periods are longer in the high load of the internal combustion engine than in the low / medium load of the internal combustion engine. The crankcase ventilation device for an internal combustion engine according to claim 1, wherein the ventilation device is changed.   The valve control means, according to the load of the internal combustion engine, when the internal combustion engine is at low to medium load, the first ventilation period is a period from the top dead center to the position after the bottom dead center. While the second ventilation period is a period from the bottom dead center to the position after the top dead center, the bottom dead center is used as the first ventilation period when the internal combustion engine is at a high load. A period from after the start time of the first ventilation period at the time of low to medium load of the internal combustion engine until the piston is positioned at the bottom dead center is defined as the second ventilation period. A period from a time earlier than the start time of the second ventilation period when the internal combustion engine is at a low to medium load to a position where the piston is located at the top dead center. One tone Changing the operation timing of the valve and the second adjustment valve, crankcase ventilation system of an internal combustion engine according to claim 2. The first ventilation passage is connected downstream of the throttle valve of the intake passage, and the second ventilation passage is connected upstream of the throttle valve of the intake passage;
The crankcase ventilation apparatus for an internal combustion engine according to any one of claims 1 to 3, wherein the valve control means determines a load on the internal combustion engine based on an opening of the throttle valve.

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