JP2010116816A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine inhibiting wrong decision in abnormal decision of a variable valve train of the internal combustion engine including an oil pressure change over mechanism capable of changing over pressure of operating oil between a high level and a low level. <P>SOLUTION: The internal combustion engine 100 includes VVT 30, 40 which are driven by oil pressure of engine oil supplied by an oil pump 51 and can change valve timing of an intake valve 11 and an exhaust valve 21, and an oil pressure change over mechanism 60 which can change over the oil pressure between the high level and the low level. An electronic control device 70 forcibly changes over oil pressure from the low level to the high level when abnormal operation of the VVT 30, 40 with the oil pressure at the low level is detected, and determines that the VVT 30, 40 are normal when the abnormal operation is removed by changing over the oil pressure to the high level. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that is driven by hydraulic pressure of hydraulic oil and includes a variable valve mechanism that can change a valve characteristic of an engine valve.

  In order to reduce pumping loss and improve fuel efficiency, an internal combustion engine having a variable valve mechanism that changes the valve characteristics of an engine valve based on the engine operating state has been widely proposed. As such an internal combustion engine, for example, the one described in Patent Document 1 is known. The internal combustion engine includes a variable valve mechanism that is driven by engine oil and can change the valve timing of the engine valve, and an oil pump that is driven by the engine output shaft and supplies engine oil to the variable valve mechanism through an oil supply circuit. Is provided. This control device for an internal combustion engine controls the valve timing of the engine valve to the advance side or the retard side by changing the connection mode of the oil supply circuit based on the engine operating state. Examples of a method for detecting such abnormality of the variable valve mechanism include the following methods. That is, when the variable valve mechanism is driven and controlled based on the engine operating state, it can be determined that the variable valve mechanism is abnormal based on the detection of an abnormal operation of the mechanism.

  Further, since the oil pressure of the engine oil necessary for normally driving the above-described variable valve mechanism increases as the engine speed increases, the oil pressure of the engine oil necessary for high engine rotation can be supplied. It is desirable to employ an oil pump. However, when an oil pump that responds to high engine speeds is used, the oil pressure of the engine oil decreases to some extent as the engine rotational speed decreases at low engine speeds. The hydraulic pressure required to drive the valve mechanism normally may be greatly exceeded.

Therefore, in order to prevent an excessive increase in the oil pressure of the engine oil at the time of low engine rotation, as described in Patent Document 2, for example, the oil pressure of the engine oil is set to a high level and a low level based on the engine rotation speed. A hydraulic switching mechanism that switches between the two can be employed. Specifically, the hydraulic pressure switching mechanism is connected to the discharge port of the oil pump, and is provided in the relief passage for relieving part of the engine oil pumped by the oil pump to the oil pan, and the relief passage. And a relief valve for switching communication and blocking of the passage. This internal combustion engine control device maintains the oil pressure of the engine oil at a high level by switching the relief passage to a shut-off state through a relief valve on condition that the engine rotational speed is higher than a predetermined determination value. On condition that the rotational speed is less than the judgment value, the relief passage is switched to the communication state through the relief valve to relieve part of the engine oil supplied by the oil pump and reduce the engine oil pressure to a low level. It is trying to switch to.
JP 2006-118419 A JP 2007-107485 A

  In this way, by switching the oil pressure of the engine oil supplied by the oil pump between the high level and the low level based on the engine rotation speed, the necessary oil pressure is supplied during high engine rotation, It is possible to reduce the torque of the engine output shaft that is consumed to drive the oil pump at the time of low rotation, and to improve the engine fuel consumption. However, when the configuration for switching the oil pressure of the engine oil is employed, the following erroneous determination may be made in the abnormality determination of the variable valve mechanism described above. In other words, for example, when the engine rotational speed is lowered while the engine oil temperature is increased due to high load operation for a long time and the oil pressure of the engine oil is switched to a low level, the engine oil temperature is switched to a low level. The applied hydraulic pressure is further lowered. As described above, when the above-described abnormality determination of the variable valve mechanism is executed in a state where the oil pressure of the engine oil is excessively lowered, the oil pressure of the engine oil drives the variable valve mechanism even if the mechanism is normal. It may be less than the hydraulic pressure required to do this. Therefore, in this case, although the variable valve mechanism is normal, an abnormal operation of the variable valve mechanism may occur, and an erroneous determination may be made that the variable valve mechanism is abnormal.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a variable valve mechanism in an internal combustion engine including a hydraulic pressure switching mechanism capable of switching the hydraulic pressure of hydraulic oil between a high level and a low level. An object of the present invention is to provide a control device for an internal combustion engine that can suppress erroneous determination of abnormality.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
According to the first aspect of the present invention, there is provided a variable valve mechanism that can be driven by hydraulic pressure of hydraulic oil to change a valve characteristic of the engine valve, and a hydraulic oil that is driven by an engine output shaft and supplies hydraulic oil to the variable valve mechanism. In a control device for an internal combustion engine, comprising: a supply mechanism; and a hydraulic pressure switching mechanism capable of switching a hydraulic pressure of the hydraulic oil supplied by the hydraulic oil supply mechanism between a high level and a low level based on an engine operating state. A switching means for forcibly switching the hydraulic pressure from the low level to the high level when an operation abnormality of the variable valve mechanism is detected in a state where the hydraulic pressure of the hydraulic oil is at the low level; A gist for determining that the variable valve mechanism is normal based on the fact that the operation abnormality has been eliminated by switching the hydraulic pressure to the high level; That.

  In this configuration, when an abnormal operation of the variable valve mechanism is detected when the hydraulic oil pressure is at a low level, the abnormal operation of the variable valve mechanism has been resolved by switching the hydraulic pressure to a high level. Based on the above, it is determined that the variable valve mechanism is normal. As a result, even when the hydraulic valve hydraulic fluid is excessively lowered due to a temperature rise or the like in the state where the hydraulic oil hydraulic pressure is at a low level, an abnormal operation of the variable valve mechanism has occurred. It is possible to suppress erroneous determination that the variable valve mechanism is abnormal. Therefore, by adopting the above configuration, an erroneous determination of abnormality determination of the variable valve mechanism is made in an internal combustion engine including a hydraulic pressure switching mechanism that can switch the hydraulic pressure of hydraulic oil between a high level and a low level. Can be suppressed.

  Note that, as described in claim 2, the determination means is based on the fact that the operation abnormality of the variable valve mechanism has been eliminated by switching the hydraulic oil pressure from the low level to the high level. While determining that it is normal, it can be determined that the hydraulic pressure of the hydraulic fluid supplied by the hydraulic fluid supply mechanism has decreased.

  According to a third aspect of the present invention, in the control apparatus for an internal combustion engine according to the first or second aspect, the determination means eliminates the operation abnormality even when the hydraulic pressure is switched to the high level by the switching means. The gist is to determine that the variable valve mechanism is abnormal based on not.

  In this configuration, it is determined that the variable valve mechanism is abnormal based on the fact that the abnormal operation of the variable valve mechanism does not disappear even when the hydraulic pressure is switched to a high level. Here, the degree of decrease in hydraulic oil pressure due to temperature rise or the like is smaller than the degree of hydraulic pressure increase due to the hydraulic oil pressure being switched from a low level to a high level. Therefore, it is possible that the hydraulic oil pressure is excessively lowered due to a temperature rise or the like when the hydraulic oil pressure is at a low level and does not meet the hydraulic pressure required to drive the variable valve mechanism. Even when an operation abnormality of the variable valve mechanism occurs, if the variable valve mechanism is normal, the operation abnormality is resolved after the hydraulic pressure is switched to a high level. Therefore, according to the above configuration, it is possible to accurately determine that the variable valve mechanism is abnormal based on the fact that the abnormal operation of the variable valve mechanism does not disappear even though the hydraulic pressure is switched to a high level. become able to.

Further, as described in claim 4, when an abnormal operation of the variable valve mechanism is detected in a state where the hydraulic oil pressure is high, it can be determined that the variable valve mechanism is abnormal. .
As a specific configuration of the hydraulic pressure switching mechanism, for example, as described in claim 5, a relief passage capable of relieving part of the hydraulic oil supplied by the hydraulic oil supply mechanism, and a relief passage provided in the relief passage are the same. It is possible to employ a configuration including a relief valve that can switch communication / blockage of the relief passage. According to such a configuration, by switching the relief passage to the communication state through the relief valve, a part of the hydraulic oil supplied by the hydraulic oil supply mechanism is relieved and the hydraulic pressure of the hydraulic oil is switched to a low level, while the relief valve is passed through the relief valve. By switching the relief passage to the cut-off state, the hydraulic oil pressure can be switched to a high level.

Hereinafter, an embodiment in which the control device for an internal combustion engine according to the present invention is embodied as an electronic control device that comprehensively controls an in-vehicle internal combustion engine will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram schematically showing an internal combustion engine and an electronic control device thereof according to the present embodiment. As shown in FIG. 1, a plurality of cylinders 1 (only one of which is shown in the figure) are formed in a cylinder block of the internal combustion engine 100, and a piston 2 reciprocates in these cylinders 1. Each is accommodated as possible. The piston 2 is connected to a crankshaft 5 that functions as an engine output shaft via a conload 4, and the reciprocating motion of the piston 2 is converted into the rotational motion of the crankshaft 5 by the conload 4 during engine operation.

  A plurality of combustion chambers 3 are defined by the top surface of the piston 2 and the inner wall of the cylinder 1. Above these combustion chambers 3, an ignition plug 6 and an in-cylinder fuel injection valve 9 are provided, and an intake port 7 and an exhaust port 8 communicating with each combustion chamber 3 are formed. The intake port 7 is connected to the intake manifold to constitute a part of the intake passage, and the exhaust port 8 is connected to the exhaust manifold to constitute a part of the exhaust passage.

  In the upper part of the combustion chamber 3, there are provided an intake valve 11 for communicating / blocking the intake port 7 and the combustion chamber 3, and an exhaust valve 21 for communicating / blocking the exhaust port 8 and the combustion chamber 3. These intake and exhaust valves 11 and 21 are opened and closed by an intake camshaft 12 and an exhaust camshaft 22 that are rotated by the crankshaft 5.

  The intake camshaft 12 and the exhaust camshaft 22 have valve timing changing mechanisms 30 and 40 (which can change the valve timings of the intake valve 11 and the exhaust valve 21 by changing the relative rotational phases of the shaft and the crankshaft 5). Hereinafter, “VVT30” and “VVT40” are provided). Hereinafter, the structure of the VVT 30 on the intake side will be described with reference to FIG. FIG. 2 is a side view mainly showing the side structure of the VVT 30. Since the structure of the VVT 40 on the exhaust side is basically the same as that on the intake side, description of the mechanism is omitted.

  The VVT 30 is provided at a proximal end portion of the intake camshaft 12 and includes a vane 31 and a housing 32 that are relatively rotatable within a predetermined range about the axis of the intake camshaft 12. The vane 31 is fixed to the intake camshaft 12, and the housing 32 is drivingly connected to the crankshaft 5 via a timing chain. A plurality of advance oil chambers 33 and retard oil chambers 34 are formed between the vane 31 and the housing 32, respectively.

  An oil pump 51 driven by the crankshaft 5 is connected to the VVT 30 via an oil supply circuit 50. During engine operation, the oil pump 51 sucks up engine oil stored in the oil pan 52 and supplies it to the VVT 30 via the oil supply circuit 50.

  Specifically, the oil supply circuit 50 is provided with a switching valve capable of switching the supply / discharge of the hydraulic oil to the advance angle oil chamber 33 and the retard angle oil chamber 34 described above. The relative timing difference between the vane 31 and the housing 32 is changed to change the valve timing of the intake valve 11 by switching the supply / discharge state of the hydraulic oil to the advance oil chamber 33 and the retard oil chamber 34. That is, when the hydraulic oil is supplied to the advance oil chamber 33 and the hydraulic oil in the retard oil chamber 34 is discharged, the vane 31 rotates relative to the housing 32 toward the advance side, and the intake valve 11 The valve timing changes to the advance side. On the other hand, when the hydraulic oil in the advance oil chamber 33 is discharged and the hydraulic oil is supplied to the retard oil chamber 34, the vane 31 rotates relative to the housing 32 toward the retard side, and the intake valve 11 The valve timing changes to the retard side. The higher the rotational speed of the crankshaft 5, that is, the engine rotational speed NE, the higher the hydraulic pressure of the engine oil supplied by the oil pump 51.

  FIG. 3 is a diagram illustrating a mode in which the valve timings of the intake valve 11 and the exhaust valve 21 change by driving the VVTs 30 and 40. As shown in FIG. 3, by changing the valve timing of the intake valve 11 and the exhaust valve 21 based on the engine operating state, the opening / closing valve timing of the intake valve 11 and the exhaust valve 21 and the overlap amount of the valve opening period Etc. can be changed.

  Here, since the oil pressure of the engine oil necessary for normally driving these VVTs 30 and 40 becomes higher as the engine speed increases, in this embodiment, the engine oil necessary for the high engine speed is increased. An oil pump 51 that can supply hydraulic pressure is employed. However, when the oil pump 51 corresponding to the high engine speed is adopted as described above, the oil pressure of the engine oil supplied by the oil pump 51 decreases to some extent as the engine rotational speed decreases during the middle low engine speed. When the engine is running at low speed, the hydraulic pressure required to drive these VVTs 30 and 40 normally may be greatly exceeded.

  Therefore, as shown in FIGS. 1 and 2, in this embodiment, a hydraulic pressure switching mechanism 60 that switches the hydraulic pressure of the engine oil supplied by the oil pump 51 between a high level and a low level is adopted. Yes. Specifically, the hydraulic pressure switching mechanism 60 is connected to a discharge port of the oil pump 51, and a relief passage 61 for relieving part of the engine oil pumped by the oil pump 51 to the oil pan 52, and the relief And a relief valve 62 provided in the passage 61 for switching communication / blocking of the passage. If the relief valve 62 is closed and the relief passage 61 is switched to the shut-off state during engine operation, the oil pressure of the engine oil is maintained at a high level. On the other hand, when the relief valve 62 is opened and the relief passage 61 is switched to the communication state, part of the engine oil supplied by the oil pump 51 is relieved to the oil pan 52, and the hydraulic pressure of the engine oil is switched to a low level. It becomes like this.

  The internal combustion engine 100 is provided with a plurality of sensors for detecting the engine operating state. For example, as shown in FIG. 1, a crank sensor 71 for detecting the rotational position of the crankshaft 5 and the engine rotational speed NE is provided in the vicinity of the crankshaft 5, and the cylinder block has a cooling function. A water temperature sensor 72 for detecting the temperature of the water is provided. Further, cam angle sensors 73 and 74 for detecting the rotational phase of these camshafts and the operation amounts of the VVTs 30 and 40 are provided in the vicinity of the intake camshaft 12 and the exhaust camshaft 22, respectively.

  The output signals of these sensors are taken in by an electronic control unit 70 that executes various controls of the internal combustion engine 100 in an integrated manner. The electronic control unit 70 includes a central processing unit that performs numerical calculation and information processing by a program, and a memory that stores programs and data necessary for various controls. During the engine operation, the electronic control unit 70 determines the engine state such as the intake air amount, the ignition timing by the ignition plug 6, and the fuel injection amount by the in-cylinder fuel injection valve 9 based on the engine operation state detected by the above-described sensors. The quantity is controlled with reference to the calculation map.

  Further, the electronic control unit 70 opens and closes the relief valve 62 based on the engine rotational speed NE detected by the crank sensor 71, thereby increasing the oil pressure of the engine oil supplied by the oil pump 51 between a high level and a low level. To switch between. Specifically, as shown in FIG. 4, when the engine rotational speed NE is higher than the determination value NE0 (3000 rpm in the present embodiment), the relief valve 62 is closed and the relief passage 61 is switched to the shut-off state. This maintains the engine oil pressure at a high level. On the other hand, when the engine rotational speed NE is equal to or less than the determination value NE0, the relief valve 62 is opened and the relief passage 61 is switched to the communication state, whereby a part of the engine oil supplied by the oil pump 51 is relieved, Switch engine oil pressure to low level. By switching the engine oil pressure between the high level and the low level in this way, the oil pressure is consumed to drive the oil pump 51 when the engine is rotating at medium and low speeds while supplying the necessary oil pressure at the time of high engine rotation. The torque of the crankshaft 5 can be reduced, and the engine fuel consumption can be improved.

  Furthermore, the electronic control unit 70 can detect an abnormality in the VVTs 30 and 40 as follows. That is, when the VVTs 30 and 40 are driven and controlled based on the engine operating state, it can be determined that the VVTs 30 and 40 are abnormal based on the occurrence of an abnormal operation of the mechanism.

  By the way, when the configuration in which the oil pressure of the engine oil is switched between the high level and the low level as in the present embodiment is adopted, the following erroneous determination may be made in the abnormality determination of the VVT 30 and 40 described above. There is. That is, for example, when the engine rotational speed NE is lowered and the engine oil pressure is switched to a low level in a state where the temperature of the engine oil has increased due to a long-time high load operation, as shown in FIG. Due to the temperature rise, the hydraulic pressure switched to the low level is further lowered. As described above, when the abnormality determination of the VVT 30 or 40 described above is executed in a state where the oil pressure of the engine oil is excessively decreased, the oil pressure of the engine oil drives the VVT 30 or 40 even if the mechanism is normal. May be less than the required hydraulic pressure ("driving minimum pressure" in FIG. 5). Therefore, in this case, there is a possibility that an erroneous determination that the VVT 30 or 40 is abnormal is made based on the occurrence of the operation abnormality even though the VVT 30 or 40 is normal.

  Therefore, the electronic control unit 70 of the present embodiment suppresses such inconvenience by executing the following abnormality determination control. Hereinafter, the abnormality determination control will be described with reference to the flowchart of FIG. Note that the series of processing shown in FIG. 6 is repeatedly executed by the electronic control unit 70 with a predetermined period.

  In this process, first, it is determined whether or not an abnormal operation of the VVT 30 or 40 has occurred (step S10). Specifically, the VVTs 30 and 40 are driven and controlled based on the engine operating state, and the VVTs 30 and 40 detected by the cam angle sensors 73 and 74 are not matched with the drive control. It can be determined that 40 drive abnormalities have occurred.

  Here, when it is determined that the operation abnormality of the VVT 30, 40 has not occurred (step S10: NO), it is determined that the VVT 30, 40 is normal (step S11), the intake air amount, the ignition timing. , And the engine state quantity such as the fuel injection quantity are set based on the normal calculation map (step S12).

  On the other hand, when it is determined that an abnormal operation of the VVT 30 or 40 has occurred (step S10: YES), it is determined whether or not the hydraulic pressure of the engine oil supplied by the oil pump 51 is low, that is, the relief valve 62. It is determined whether or not the valve is open (step S20). When it is determined that the relief valve 62 is closed (step S20: NO), in other words, when an abnormal operation of the VVT 30 or 40 occurs while the engine oil pressure is high. Then, it is determined that these VVTs 30 and 40 are abnormal (step S21), and fail processing including retreating of the vehicle is performed (step S22).

  If it is determined that the relief valve 62 is open (step S20: YES), the oil pressure of the engine oil is increased from a low level to a high level by changing the relief valve 62 from the open state to the closed state. The level is switched (step S30). Then, it is determined whether or not the abnormal operation of the VVTs 30 and 40 has been eliminated by switching the hydraulic pressure to the high level in this way (step S40).

  Here, when it is determined that the operation abnormality of the VVTs 30 and 40 has not been resolved (step S40: NO), it is determined that these VVTs 30 and 40 are abnormal (step S21), and the vehicle evacuates and the like. Fail processing including the above is executed (step S22). On the other hand, when it is determined that the operation abnormality of VVT 30 and 40 has been resolved (step S40: YES), VVT 30 and 40 are normal, and the oil pressure of the engine oil is temporarily reduced due to a temperature rise. Determination is made (step S50).

  Then, by changing the relief valve 62 to the open state, the oil pressure of the engine oil is switched from the high level to the low level, and the engine state quantity is set based on the calculation map for when the oil pressure decreases, which is stored in advance in the memory. (Step S60). This calculation map when the hydraulic pressure drops is such that when the hydraulic pressure drop causes a temporary drive abnormality of the VVTs 30 and 40, the valve timings of the intake valve 11 and the exhaust valve 21 cannot be changed. FIG. 6 is a calculation map for setting engine state quantities such as intake air quantity, ignition timing, and fuel injection quantity so as to stabilize the engine operating state.

According to the embodiment described above, the following effects can be obtained.
(1) When an abnormal operation of the VVT 30, 40 is detected in a state where the oil pressure of the engine oil is at a low level, the abnormal operation of the VVT 30, 40 is resolved by switching the hydraulic pressure to a high level. It is determined that the VVT 30 and 40 are normal and the hydraulic pressure of the hydraulic oil supplied by the oil pump 51 is lowered due to the temperature rise. As a result, in the state where the oil pressure of the engine oil is at a low level, even if an abnormal operation of the VVT 30, 40 occurs due to excessive decrease in the oil pressure of the engine oil due to the temperature rise, the VVT 30, 40 Can be prevented from being erroneously determined to be abnormal. Therefore, in the internal combustion engine 100 including the oil pressure switching mechanism 60 that can switch the oil pressure of the engine oil between a high level and a low level, it is possible to suppress erroneous determination of abnormality determination of the VVTs 30 and 40.

  (2) Based on the fact that the abnormal operation of the VVT 30 and 40 is not resolved even when the hydraulic pressure is switched to a high level, it is determined that the VVT 30 and 40 are abnormal. Here, as shown in FIG. 5, the degree of decrease in the oil pressure of the engine oil due to a temperature rise or the like is smaller than the degree of increase in the oil pressure caused by switching the oil pressure of the engine oil from the low level to the high level. Therefore, if the oil pressure of the engine oil is at a low level, the hydraulic oil pressure of the hydraulic oil is excessively lowered due to a temperature rise, and the VVT 30, 40 is not satisfied with the oil pressure required to drive the VVT 30, 40. Even if the abnormal operation occurs, if the VVT 30, 40 is normal, the abnormal operation is resolved after the hydraulic pressure is switched to a high level. Therefore, it is possible to accurately determine that the VVT 30, 40 is abnormal based on the fact that the abnormal operation of the VVT 30, 40 is not resolved despite the hydraulic pressure being switched to a high level.

  (3) When an abnormal operation of the VVT 30 or 40 is detected in a state where the oil pressure of the engine oil is at a high level, the abnormal operation is not an abnormal operation due to a decrease in the oil pressure of the engine oil. It can be determined that there is an abnormality.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, when an abnormal operation of the VVT 30 or 40 occurs when the oil pressure of the engine oil is low, the abnormal operation is eliminated by switching the hydraulic pressure to a high level (step S40). : YES) It is determined that the VVT 30 and 40 are normal and the hydraulic pressure is reduced. However, even when the hydraulic pressure is not lowered, for example, a slight biting or the like occurs in the VVT 30 or 40, so that an abnormal operation of the VVT 30 or 40 occurs in a state where the hydraulic pressure is low, and the hydraulic pressure is high. There is a possibility that the biting is eliminated by switching to. If an abnormal operation of the VVT 30 or 40 occurs due to slight biting or the like in this way, an erroneous determination that the hydraulic pressure is reduced is made. In order to suppress such inconvenience, for example, the abnormality determination control shown in the flowchart of FIG. 7 can be executed. That is, when it is determined that an operation abnormality of VVT 30 or 40 has occurred (step S10: YES), whether or not the temperature T of the cooling water detected by the water temperature sensor 72 is higher than a predetermined determination temperature T0. Is determined (step S15). Here, when it is determined that the temperature T is equal to or lower than the determination temperature T0 (step S15: NO), it is determined that the temperature of the engine oil has not increased excessively, and the VVT 30 is caused by a decrease in hydraulic pressure. , 40 is less likely to occur, and it is determined that VVT 30, 40 is abnormal (step S21). By executing such abnormality determination control, the accuracy of abnormality determination of the VVTs 30 and 40 can be further improved.

  In addition, when there is a possibility that an abnormal operation may occur in a state where the VVT 30, 40 is normal due to factors other than a decrease in the hydraulic pressure, for example, the abnormal operation of the VVT 30, 40 may occur when the hydraulic pressure is at a high level. When it occurs (step S20: NO or step S40: NO), it is possible to adopt a configuration for further determining whether or not the abnormal operation of the VVT 30 or 40 is caused by the factor.

  In the above embodiment, when the VVTs 30 and 40 are normal and the oil pressure is reduced (step S40: YES), the engine state quantity is changed based on the calculation map when the oil pressure is lowered by switching the oil pressure to a low level. Is set (step S60). On the other hand, for example, in order to give priority to the control of the valve timing of the intake valve 11 and the exhaust valve 21, when it is determined that the VVT 30, 40 is normal and the hydraulic pressure is reduced, the hydraulic pressure is set to a high level. It is also possible to set the engine state quantity based on a normal calculation map.

  In the above embodiment, the relief passage 61 that reliefs part of the engine oil supplied by the oil pump 51 and the communication of the relief passage 61 are used as a hydraulic pressure switching mechanism that switches the hydraulic pressure of the engine oil between a high level and a low level. A hydraulic switching mechanism 60 including a relief valve 62 that switches off is adopted. Not only this but the mechanism which switches the capacity | capacitance (discharge amount) of the oil pump 51 between a high level and a low level is also employable, for example.

  In the above-described embodiment, the case where the present embodiment is applied to the control device for the internal combustion engine including the VVTs 30 and 40 that change the valve timings of the intake valve 11 and the exhaust valve 21 is illustrated. For example, control of an internal combustion engine that is driven by the oil pressure of engine oil and includes a variable valve mechanism that changes other valve characteristics of the engine valve, such as the maximum lift amount and operating angle of the intake valve 11 or the exhaust valve 21. In the apparatus, the present invention can be applied in basically the same manner.

1 is a schematic configuration diagram schematically illustrating an internal combustion engine and an electronic control device thereof according to an embodiment of the present invention. The side view which mainly shows the side structure of the valve timing change mechanism which concerns on the embodiment. The figure which shows the aspect from which the valve timing of an intake valve and an exhaust valve changes by the drive of the said valve timing change mechanism. The figure which shows the switch aspect of the hydraulic pressure accompanying the change of rotational speed by the hydraulic pressure switching mechanism which concerns on the embodiment. The figure which shows the aspect that oil_pressure | hydraulic falls with the raise of the temperature of engine oil. The flowchart which shows the process sequence about the abnormality determination control performed by the electronic control apparatus which concerns on the same embodiment. The flowchart which shows the process sequence about the modification of the said abnormality determination control.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cylinder, 2 ... Piston, 3 ... Combustion chamber, 4 ... Comload, 5 ... Crankshaft, 6 ... Spark plug, 7 ... Intake port, 8 ... Exhaust port, 9 ... In-cylinder fuel injection valve, 11 ... Intake valve, DESCRIPTION OF SYMBOLS 12 ... Intake camshaft, 21 ... Exhaust valve, 22 ... Exhaust camshaft, 30, 40 ... Valve timing change mechanism, 31 ... Vane, 32 ... Housing, 33 ... Advance oil chamber, 34 ... Delay oil chamber, 50 ... Oil supply circuit, 51 ... oil pump (hydraulic oil supply mechanism), 52 ... oil pan, 60 ... hydraulic switching mechanism, 61 ... relief passage, 62 ... relief valve, 70 ... electronic control device (switching means, determination means), 71 ... crank sensor, 72 ... water temperature sensor, 73, 74 ... cam angle sensor, 100 ... internal combustion engine.

Claims (5)

A variable valve mechanism that can be driven by hydraulic pressure of hydraulic oil to change the valve characteristics of the engine valve, a hydraulic oil supply mechanism that is driven by the engine output shaft and that supplies hydraulic oil to the variable valve mechanism, and based on engine operating conditions A control apparatus for an internal combustion engine comprising a hydraulic pressure switching mechanism capable of switching the hydraulic pressure of the hydraulic oil supplied by the hydraulic oil supply mechanism between a high level and a low level;
A switching means for forcibly switching the hydraulic pressure from the low level to the high level when an abnormal operation of the variable valve mechanism is detected in a state where the hydraulic pressure of the hydraulic oil is at the low level;
An internal combustion engine comprising: a determination unit that determines that the variable valve mechanism is normal based on the fact that the operation abnormality has been eliminated by switching the hydraulic pressure to the high level by the switching unit. Control device. The control apparatus for an internal combustion engine according to claim 1,
The determination means determines that the hydraulic pressure of the hydraulic oil supplied by the hydraulic oil supply mechanism has decreased based on the fact that the operation abnormality has been eliminated by the hydraulic pressure being switched to the high level by the switching means. A control device for an internal combustion engine. The control device for an internal combustion engine according to claim 1 or 2,
The determination means determines that the variable valve mechanism is abnormal based on the fact that the abnormal operation is not solved even when the hydraulic pressure is switched to the high level by the switching means. Control device. The control apparatus for an internal combustion engine according to any one of claims 1 to 3,
The determination means determines that the variable valve mechanism is abnormal when an abnormal operation of the variable valve mechanism is detected in a state where the hydraulic pressure of the hydraulic oil is at the high level. Control device for internal combustion engine. In the control device for an internal combustion engine according to any one of claims 1 to 4,
The hydraulic pressure switching mechanism includes a relief passage that can relieve part of the hydraulic oil supplied by the hydraulic oil supply mechanism, and a relief valve that is provided in the relief passage and switches communication / blocking of the relief passage. A control device for an internal combustion engine.

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