JP2017031868A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine which can reduce the deterioration of an exhaust gas when an abnormality occurs in one variable valve timing mechanism, in the internal combustion engine having variable valve timing mechanisms at an intake side and an exhaust side.SOLUTION: A control device 1 of an internal combustion engine comprises variable valve timing mechanisms (VVT3, 4) at an intake side and an exhaust side, and a control part 6 which controls the variable valve timing mechanisms so as to be operated in leakage. The control part 6 comprises a valve timing command part 64 which commands the other VVT to be operated according to a fixed phase of a cam at a side at which the abnormality occurs so that a cam at a normal side is displaced to a state which is deviated to the same side as a state which is deviated to an advance side or a retardation side from a normal time at a phase of the cam at the side at which the abnormality occurs when it is determined that the abnormality exists at one VVT. Since the cam at the normal side is displaced according to the fixed phase, the deterioration of combustion is improved, and the deterioration of an exhaust gas can be reduced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device that controls an internal combustion engine that includes a variable valve timing mechanism that changes opening and closing timings of intake valves and exhaust valves in accordance with the operating state of the internal combustion engine.

  As an internal combustion engine mounted on an automobile, a variable valve timing mechanism (hereinafter sometimes referred to as VVT) that changes the opening / closing timing of an intake valve or an exhaust valve according to an operating state such as an engine speed or an engine load. (For example, refer to Patent Document 1).

  A camshaft equipped with a cam that opens and closes an intake valve and an exhaust valve is typically provided with a sprocket near its end, and the rotation of the crankshaft is transmitted via a timing chain or timing belt that spans the sprocket. Rotate. By the rotation of the cam shaft, the basic opening / closing timing of each valve according to the cam profile is determined. The VVT is typically attached to a camshaft, and rotates the camshaft at a predetermined angle relative to the sprocket (see below for detailed configuration), and is basically based on the rotation of the crankshaft. Each valve opening / closing timing is shifted according to the predetermined angle. The VVT that rotates the camshaft hydraulically is called a hydraulic type, and the VVT that uses an electric motor is called an electric type.

  VVT is normally controlled by an electronic control unit (ECU). In the electronic control unit, the opening / closing timing of each valve suitable for each operating state is set and stored. The electronic control unit checks the driving state based on information from various sensors during driving of the automobile, selects the opening / closing timing of each valve suitable for the current driving state, and controls the VVT.

  In an internal combustion engine having both an intake side VVT and an exhaust side VVT, the degree of freedom in adjusting the opening / closing timing of the intake valve and the opening / closing timing of the exhaust valve is high. For example, referring to the valve timing diagram of FIG. 3 for an internal combustion engine that has both an intake side VVT and an exhaust side VVT and performs a mirror cycle (sometimes referred to as an Atkinson cycle), an example of opening and closing timing of each valve Will be explained. In FIG. 3, the inner periphery diagram with wide hatching shows the diagram of the exhaust valve (Ex), and the outer periphery diagram with narrow hatching shows the valve timing of the intake valve (In).

  As shown in FIG. 3 (C), when the load is low and the rotation is low, the closing timing (close) of the intake valve is set to the retarded side sufficiently past the bottom dead center (BDC), as shown in FIG. 3 (D). In particular, when the load is high and the rotation is high, the closing timing of the intake valve (close) can be advanced from the closing timing when the load is low and the rotation is low. As a result, when the load is low and the rotation is low, the expansion ratio is sufficiently higher than the compression ratio and the thermal efficiency is increased. In addition, the compression ratio is small and knocking can be suppressed. To obtain great power.

  When starting or idling, as shown in FIGS. 3A and 3B, the exhaust valve closing timing (close) is set immediately after the top dead center (TDC), and the intake valve opening timing (open) is set to the exhaust gas. No overlap is provided on the retarded side of the valve closing timing (close), and the intake valve opening timing (open) advances more than the exhaust valve closing timing (close) close to TDC at high load and high rotation. An overlap can be provided on the corner side. As a result, during start-up and idling, exhaust gas is not sucked in and combustion is easy to stabilize, and at high loads and high rotations, a scavenging effect and NOx reduction effect due to exhaust gas recirculation (internal EGR) can be obtained.

JP 2003-206767 A

  In an internal combustion engine equipped with both an intake side variable valve timing mechanism and an exhaust side variable valve mechanism, it is desirable to be able to reduce the deterioration of exhaust gas when an abnormality occurs in one VVT. In particular, even when this internal combustion engine performs a mirror cycle, it is desired that the combustion stability is excellent and deterioration of exhaust gas can be reduced.

  VVT abnormalities include those called sticking abnormalities in which the camshaft cannot be rotated to a predetermined angle when the VVT is operated by biting foreign matter or the like contained in engine oil supplied into the VVT. If a sticking abnormality occurs in one VVT, the opening / closing timings of the intake valve and the exhaust valve in each operation state are not in an appropriate state, and a desired effect cannot be obtained satisfactorily.

  For example, in the internal combustion engine that performs the above-described mirror cycle, consider a case where the exhaust valve is fixed so that the closing timing of the exhaust valve is on the retard side from the top dead center (TDC). In this case, when the intake-side VVT is operated in the same way as during normal operation at high load and high speed as shown in FIG. 4 (d), the overlap is extremely large as shown by the two-dot chain line in FIG. 4 (d). Become bigger. If the overlap is too large, the amount of exhaust gas in the mixture of fuel and air will increase, combustion will not be stable, and misfire will be likely to occur, exhaust gases will deteriorate, for example non-methane hydrocarbons (NMHC) An increase can be invited. When starting or idling, if the VVT on the intake side is operated in the same manner as normal, an overlap can occur and a misfire tends to occur.

  In this way, when an abnormality occurs in one of the VVTs, if the other VVT is operated in the same manner as normal, exhaust gas may be easily deteriorated.

  In Patent Document 1, when a sticking abnormality occurs in one of the VVTs, the other VVT is controlled so that the overlap is minimized, and at least one of increasing the idle rotation speed from normal is performed. Disclose. The specific control of the VVT is based on whether the opening / closing timing on the normal side is the most advanced angle position (when the intake side is abnormal and the exhaust side is normal) or the most retarded position (the exhaust side is abnormal and the intake side is If it is normal). In this control, regardless of the magnitude of the cam angle at the time of fixing, the overlap is minimized by substantially setting the fixed position as the most retarded angle position or the most advanced angle position (see FIG. 7 of Patent Document 1). (See solid line). Therefore, in the operation state in which overlap is desired as described above, the effect due to the overlap cannot be substantially obtained. In the internal combustion engine that performs the mirror cycle shown in FIG. 3 described above, if the closing timing of the intake valve, which is normal when the closing timing of the exhaust valve is fixed on the retarded side as described above, is set to the most retarded position, it is In addition, sufficient overlap is not provided at the time of load and high rotation, and the closing timing of the intake valve is further delayed, resulting in insufficient compression, which may cause instability of combustion.

  Accordingly, one of the objects of the present invention is to reduce deterioration of exhaust gas when an abnormality occurs in one variable valve timing mechanism in an internal combustion engine having both an intake side variable valve timing mechanism and an exhaust side variable valve mechanism. An object of the present invention is to provide a control device for an internal combustion engine.

An internal combustion engine control apparatus according to an aspect of the present invention includes an intake side variable valve timing mechanism that changes a phase of an intake side cam that opens and closes an intake valve, and an exhaust side variable that changes a phase of an exhaust side cam that opens and closes an exhaust valve. A valve timing mechanism and a control unit that controls the valve timing mechanism to operate in cooperation with each other are provided.
The control unit includes a cam angle calculation unit that calculates the phase of the intake side cam and the phase of the exhaust side cam, and the intake side variable valve timing mechanism and the exhaust side variable valve based on the calculated phases of both cams. An abnormality determination unit that determines whether there is an abnormality in the timing mechanism, and a valve timing command unit described below.
The valve timing command unit is the cam angle calculation unit in the cam operated by the one variable valve timing mechanism having an abnormality when the abnormality determination unit determines that the one variable valve timing mechanism has an abnormality. In accordance with the calculated phase, the cam on the normal side is displaced to a state shifted to the same side as the state shifted to the advance side or retard side from the normal phase of the cam on the abnormal side. Thus, the other variable valve timing mechanism is commanded to operate.

  When it is determined that one of the variable valve timing mechanisms (VVT) is abnormal, the control device for the internal combustion engine according to the phase of the cam on the abnormal side (hereinafter sometimes referred to as a fixing phase). Thus, the cam operated by the other normal VVT is displaced to the same advance side or retard side as the cam on the abnormal side. Therefore, the control device for the internal combustion engine is brought close to the normal operating environment even when an abnormality occurs in one of the VVTs. Therefore, according to the control device for an internal combustion engine described above, even when an abnormality occurs in one VVT, it is possible to make the operation environment close to a normal operation environment set for each operation state to some extent, and the other VVT. As compared with the case where the engine is operated in the same manner as normal, deterioration of exhaust gas can be reduced. Further, even when the internal combustion engine performs a mirror cycle, deterioration of exhaust gas can be reduced.

2 is a functional block diagram of a control device for an internal combustion engine according to Embodiment 1. FIG. 3 is a flowchart illustrating an example of a control procedure by the control device for an internal combustion engine according to the first embodiment. FIG. 3 is a timing diagram showing an example of opening and closing timings of intake valves and exhaust valves for each operating state for an internal combustion engine that performs a mirror cycle, where (A) is a start time, (B) is an idle time, and (C) is a low load At low rotation, (D) shows a high load and high rotation. 3 is a timing diagram showing an example in which the intake side variable valve timing mechanism is operated to adjust the opening / closing timing of the intake valve when an abnormality occurs in the exhaust side variable valve timing mechanism by the control device for the internal combustion engine of the first embodiment. (C) is a diagram when the exhaust side VVT is fixed to the advance side than normal, and (d) is a diagram when the exhaust side VVT is fixed to the retard side than normal. The diagram at the time of high load and high rotation is shown.

  Hereinafter, a control device for an internal combustion engine of the present invention will be described in detail with reference to the drawings. In the figure, the same reference numerals indicate the same names.

[Embodiment 1]
(overall structure)
The internal combustion engine control apparatus 1 according to the first embodiment is mounted on a vehicle (not shown) such as an automobile, and is used to control each component of the internal combustion engine 2 that generates a driving force that the vehicle travels. The internal combustion engine 2 ignites an air-fuel mixture containing fuel and air with the spark plug 5 and burns it in the combustion chamber 22C to generate the driving force. The internal combustion engine 2 includes an intake side variable valve timing mechanism 3 (hereinafter referred to as InVVT3) that changes the phase of an intake side cam (not shown) that opens and closes an intake valve 30, and an exhaust side cam that opens and closes an exhaust valve 40 (see FIG. An exhaust side variable valve timing mechanism 4 (hereinafter, ExVVT4) for changing the phase of the ignition plug 5 is provided. The control device 1 includes an InVVT 3, an ExVVT 4, and a control unit (ECU) 6 that controls them to operate in association with each other.

  In the control device 1 for an internal combustion engine according to the first embodiment, the control unit 6 determines whether there is an abnormality in the InVVT3 and ExVVT4, and when it is determined that one VVT is abnormal, the phase of the cam on the abnormal side is determined. One of the characteristics is that the other VVT is operated so as to displace the cam operated by the other VVT that is normal and has no abnormality according to (fixing phase). First, each component of the internal combustion engine 2 and the control unit 6 will be described with reference to FIG.

(Internal combustion engine)
The internal combustion engine 2 typically includes a laminate in which an oil pan (not shown), a cylinder block 20, a cylinder head 22, and a cylinder head cover 24 are assembled in order from the bottom.
The cylinder block 20 includes a cylinder bore 20B, and includes a piston 20P that linearly reciprocates within the bore 20B using combustion pressure, and a main shaft such as a crankshaft 20C that converts the linear reciprocation of the piston 20P into rotational motion. Stores the motor system.
The cylinder head 22 includes an intake port 223 for introducing air, a combustion chamber 22C for burning an air-fuel mixture including fuel injected from the injector 8 and air introduced from the intake port 223, and exhaust gas generated in the combustion chamber 22C. And an exhaust port 224 for discharging the air. The cylinder head 22 is disposed at the boundary between the ports 223 and 224 and the combustion chamber 22C, and has an intake valve 30 for opening and closing the combustion chamber 22C, an exhaust valve 40, and an intake side cam (not shown) for opening and closing the intake valve 30. A valve operating system such as an intake side camshaft 30C provided and an exhaust side camshaft 40C provided with an exhaust side cam (not shown) for opening and closing the exhaust valve 40 is housed.
Although FIG. 1 shows a mode in which the injector 8 is attached to the intake port 223 and fuel is injected into the intake port 223 (port injection type), a mode in which fuel is directly injected into the combustion chamber 22C (direct injection type) can be used. .
An intake manifold 93 is connected to the intake port 223 to introduce air that has passed through an air cleaner (not shown). Air is introduced into the combustion chamber 22C via the intake port 223 and the intake valve 30 in the open state. An exhaust manifold 94 is connected to the exhaust port 224, and exhaust gas is discharged outside the vehicle through a catalytic converter (not shown).
The internal combustion engine 2 performs four-cycle operation of intake, compression, combustion, and exhaust using the combustion of the air-fuel mixture.

-Variable valve timing mechanism The basic configuration and functions of InVVT3 and ExVVT4 are the same, and a known configuration can be used. InVVT3 in this example is an electric VVT, and ExVVT4 is a hydraulic VVT. The electric VVT can operate regardless of the temperature of the engine oil, and can operate well even at the start-up when the engine oil is at a low temperature. The hydraulic VVT is widely used and easy to use. Hereinafter, an example of each VVT 3 and 4 will be briefly described.

The electric VVT used for the InVVT 3 includes an electric motor 32 disposed at the end of the intake camshaft 30C and a phase change mechanism 34.
The motor 32 has a motor shaft a that is rotatably disposed coaxially with the cam shaft 30C, a magnet is disposed on the outer peripheral surface, a rotor (not shown) that is integral with the motor shaft a, and an outer periphery of the rotor. And a stator (not shown) composed of a coil and a coil. When the coil is energized by the controller 6 and a rotating magnetic field is formed on the outer periphery of the motor shaft a, the motor shaft a rotates clockwise or counterclockwise according to the rotating magnetic field.
The phase change mechanism 34 is coaxially fixed to an output shaft (not shown) coaxially fixed to the end portion of the intake camshaft 30C, a sprocket s coaxially provided on the outer periphery of the output shaft, and an inner peripheral wall of the sprocket s. An inner ring gear r, an eccentric shaft d connected and fixed to the motor shaft a, a planetary gear p provided on the inner periphery of the ring gear r and having outer teeth meshing with the inner teeth. The output shaft is provided with a disk-like engagement portion having a plurality of engagement holes provided at equal intervals in the circumferential direction, and a plurality of planetary gears p are provided at positions corresponding to the engagement holes (not shown). With protrusions. A timing chain or the like (not shown) is bridged between the sprocket s and a sprocket (not shown) provided on the crankshaft 20C, so that the camshaft 30C can rotate in synchronization with the crankshaft 20C. The motor shaft a is provided to be rotatable relative to the sprocket s.

When the InVVT 3 is not operated and the motor shaft a does not rotate relative to the sprocket s, the planetary gear p rotates integrally with the sprocket s while being engaged with the ring gear r as the crankshaft 20C rotates. At this time, since the protrusion presses the inner wall of the engagement hole in the rotation direction, the output shaft rotates in the same direction with respect to the sprocket s.
When an operation command is issued from the control unit 6 to the InVVT 3 and the motor shaft a rotates relative to the sprocket s, the planetary gear p rotates relative to the eccentric shaft d by planetary motion, while the ring gear r meshes. Change position. The direction in which the protrusions press the inner wall of the engagement hole changes depending on the rotation direction of the relative rotation, and the phase can be shifted to the advance side and the retard side.

The hydraulic VVT used for the ExVVT 4 includes a case 41 attached to the end of the exhaust camshaft 40C, and a vane 42 that is housed in the case 41 and is rotatable relative to the case 41. A sprocket (not shown) is provided on the outer peripheral surface of the case 41, and a timing chain or the like is bridged between the sprocket and a sprocket provided on the crankshaft 20C. The case 41 is synchronized with the crankshaft 20C. It can be rotated. The rotation of the case 41 causes the cam shaft 40C to rotate.
The inner surface of the case 41 is provided with a plurality of shaft-side protrusions that protrude toward the center of the cam shaft 40C and are spaced apart from each other at a predetermined interval in the circumferential direction of the cam shaft 40C.
The vane 42 accommodated in the case 41 is provided so as to be rotatable relative to the sprocket (case 41). The outer periphery of the vane 42 is provided with a plurality of vane side projecting portions projecting radially outward. The vane-side protrusion is disposed so as to be interposed between the above-described shaft-side protrusions. Of the two shaft-side protrusions sandwiching the vane-side protrusion, one is provided on the further advance side than the most advanced position of the exhaust side cam, and the other is further on the most retarded position of the exhaust side cam. Provided on the retard side.

When the ExVVT 4 is not operated, as illustrated in FIG. 1, the vane-side protrusion is held at a substantially intermediate position between the shaft-side protrusions. Since both shaft side protrusions are arranged at positions away from both the most advanced angle side and the most retarded angle side as described above, the case 41 rotates when the case 41 rotates in synchronization with the rotation of the crankshaft 20C. The cam shaft 40C integrated with the shaft rotates without being restricted by the shaft-side protruding portion and the vane-side protruding portion, and the exhaust-side cam takes a predetermined phase.
When an operation command is issued to the ExVVT 4 from the control unit 6, the vane 42 is rotated by a predetermined angle between the shaft-side protruding portions by hydraulic pressure. In this state, if the case 41 rotates with the rotation of the crankshaft 20C, the cam phase can be shifted by the predetermined angle from when the VVT is not operated.

  The internal combustion engine 2 of this example performs a mirror cycle by adjusting the cam profile and the cam arrangement positions on both cam shafts 30C and 40C so that the expansion ratio is larger than the compression ratio. Further, the internal combustion engine 2 of this example includes VVTs 3 and 4 and operates the VVTs 3 and 4 in accordance with the operating state to change the phase of both cams, thereby increasing the expansion ratio in a specific operating state. It can be made larger or the compression ratio can be made larger (see FIG. 3).

For example, as shown in FIG. 3C, at the time of low load and low rotation, the InVVT 3 is controlled so that the closing timing (close) of the intake valve 30 is sufficiently retarded from the bottom dead center (BDC). Thus, the compression ratio can be sufficiently reduced, and the expansion ratio can be further increased.
As shown in FIG. 3D, when the load is high and the rotation is high, the compression ratio can be increased by making the closing timing of the intake valve 30 closer to the advance side than when the load is low and the rotation is low. In addition, the opening timing (open) of the intake valve 30 is set before the top dead center (TDC) (advanced side), and the closing timing (close) of the exhaust valve 40 is set near the top dead center (TDC). By controlling InVVT3 and ExVVT4 in such a manner, an overlap can be provided before the top dead center (TDC) (on the advance side).
As shown in FIGS. 3A and 3B, at the time of start-up and idling, the closing timing (close) of the exhaust valve 40 is made close to top dead center (TDC) and the opening timing (open) of the intake valve 30 is set. By setting the exhaust valve 40 later (closed side) than the closing timing (closing), the overlap can be eliminated and the compression ratio can be made relatively small.

(Control part)
Each component of the internal combustion engine 2 such as InVVT 3, ExVVT 4, and other spark plugs 5 is controlled by the control unit 6. The control unit 6 receives signals from various sensors attached to the vehicle, appropriately calculates the obtained signals, and commands predetermined components to each component based on the calculation results. The control unit 6 has a self-diagnosis function (OBD). When an abnormality occurs in each component, the controller 6 instructs an operation for an abnormality set in advance in each component, a warning light, or the like. To inform the driver of the abnormality. Such a control unit 6 includes a reception unit that receives signals from various sensors, a calculation unit that uses the received signal as an appropriate calculation value, and a determination unit that compares and determines the calculation result and stored information. And a command unit that commands each component according to the determination result (none of which is shown). The control unit 6 includes a storage unit 65 that stores various types of information. As the basic configuration of the control unit 6, a known configuration used for an electronic control unit of an automobile can be used.

  Parameters used for control include engine speed, engine load (torque), coolant temperature, accelerator opening or accelerator depression, vehicle speed, intake air, throttle valve opening, air-fuel ratio, and oxygen content in exhaust gas. Can be mentioned. Since the control unit 6 controls the InVVT3 and ExVVT4 according to each operation state such as at the time of start-up, idling, low load / low rotation, high load / high rotation, etc., signals from various sensors are transmitted. It calculates appropriately and acquires the parameter used for grasping the driving state. For example, since the engine speed can be grasped by the rotation angle of the crankshaft 20C, a signal from the crank angle sensor 26 can be used. Since the engine load can be grasped by, for example, the coolant temperature, the accelerator opening, the vehicle speed, the throttle valve opening, and the like, it is possible to use signals from a temperature sensor, an accelerator sensor, a vehicle speed sensor, a throttle sensor, and the like. A known sensor can be used as the sensor.

  In grasping the operation state, for example, an operation state map represented by the engine speed and the engine load is set in advance and stored in the storage unit 65. A basic map of the adjustment amount of the intake side cam by InVVT3 and a basic map of the adjustment amount of the exhaust side cam by ExVVT4 (hereinafter sometimes collectively referred to as a basic cam map) according to each operation state are also set in advance. This is stored in the storage unit 65.

  In addition, the control unit 6 includes an ignition control unit (not shown) that controls ignition timing by the spark plug 5 for the purpose of preventing knocking and improving fuel consumption. The ignition timing corresponding to each operating state is set in advance and stored in the storage unit 65.

  In particular, the control unit 6 included in the control device 1 for an internal combustion engine according to the first embodiment determines that there is an abnormality in one VVT by the abnormality determination unit 62 that determines whether there is an abnormality in InVVT3 and ExVVT4. The cam on the normal side with no abnormality is the same as the cam on the abnormal side according to the phase at this time (fixed phase, phase calculated by the cam angle calculation unit) of the cam on the abnormal side. One of the features is that it includes a valve timing command unit 64 that commands the other VVT that is normal and has no abnormality so as to be displaced to a state deviated. Further, the control unit 6 includes a cam angle calculation unit 60 that calculates the phase of the intake side cam and the phase of the exhaust side cam. The abnormality determination unit 62 determines the presence or absence of abnormality based on the calculated phase of both cams.

  The current phase of each cam is obtained by using the rotation angle (crank angle) of the crankshaft 20C and the rotation angles (cam angle) of the camshafts 30C and 40C. Specifically, an angle difference between the crank angle and the cam angle is obtained, and each current angle depends on how much the angle difference is advanced or retarded from a reference angle difference set by appropriate learning or the like. The phase of the cam is obtained (see, for example, Patent Document 1). Therefore, the control device 1 of this example is provided with an intake side cam angle sensor 36 and an exhaust side cam angle sensor 46 which are attached to InVVT3 and ExVVT4, respectively, and detect the rotation angles of the camshafts 30C and 40C. A crank angle sensor 26 that is attached to 20C and detects the rotational speed of the crankshaft 20C is provided. The cam angle calculation unit 60 calculates the phase of each cam using signals from the sensors 26, 36, and 46.

  A cam operated on the other VVT that is normal and has no abnormality (a cam on the normal side) is controlled by the other VVT based on a command from the valve timing command unit 64, so that one VVT having the abnormality is operated. In the phase of the cam operated at (the cam on the abnormal side), it is displaced to a state shifted to the same side as the state shifted from the normal time to the advance side or the retard side. In short, when it is determined that there is an abnormality in one VVT, the phase of the cam on the normal side is advanced or retarded to the same side as the phase of the cam on the abnormal side. In addition, the shift amount at this time is set to a value set in advance according to the magnitude of the phase (fixed phase) of the cam on the abnormal side.

For each operating state, the shift amounts α, β (FIG. 4) corresponding to the fixing phase θ at the time of abnormality (the amount of displacement toward the advance side or the amount of displacement toward the retard side from the normal state, FIG. 4), etc. It is set in advance and stored in the storage unit 65. There is a tendency for the shift amount to increase as the fixing phase θ increases.
The shift amounts α, β, etc. are desirably set so as to approach the normal operating environment.
For example, in the internal combustion engine 2 that performs the mirror cycle, the opening / closing timing of the exhaust valve 40 is set to the advance side at the time of low load and low rotation as shown in FIG. When the ExVVT 4 is fixed so as to be positioned, the opening / closing timing of the intake side valve 30 is shifted to the advance side as seen from the normal state shown in FIG. 3C, similarly to the exhaust valve 40 operating on the advance side. The intake side cam is displaced by operating the normal InVVT 3 based on a preset intake side shift amount β in accordance with the exhaust side fixing phase θ at this time.
Further, for example, as shown in FIG. 4 (d), the ExVVT 4 is fixed so that the opening / closing timing of the exhaust valve 40 is located on the retard side when viewed from the normal state shown in FIG. In the case, the opening / closing timing of the intake side valve 30 is shifted to the retarded side as seen from the normal time shown in FIG. 3D, similarly to the exhaust valve 40 operating on the retarded side. In response to the exhaust-side fixing phase θ at this time, the normal InVVT 3 is operated based on a preset intake-side shift amount α to displace the intake-side cam.
Similarly, in other operating states, the intake-side shift amount is set in advance in accordance with the exhaust-side fixing phase θ. Similarly, when the InVVT 3 is fixed, the shift amount on the exhaust side is set in advance according to the fixing phase for each operation state.

(Control procedure)
A specific example of the control procedure by the control unit 6 will be described with reference to FIG.
The control unit 6 receives signals from the cam angle sensors 36 and 46 and the crank angle sensor 26, and the cam angle calculation unit 60 calculates the phase of the intake side cam and the phase of the exhaust side cam using these signals. (Step S10).

  The abnormality determination unit 62 determines whether there is an abnormality in InVVT3 and ExVVT4 based on the calculated phase of both cams (Sstep S11). Specifically, the control unit 6 calls a basic cam map corresponding to the current operating state from the storage unit 65, and calculates a calculated value and a phase of the basic cam map (a phase that can be originally taken if normal) for each VVT. It is determined whether the difference is within a predetermined range set in advance.

  If the above difference is within a predetermined range, it can be said that both VVTs are not abnormal, and the abnormality determining unit 62 determines that there is no abnormality (normal). When it is determined that there is no abnormality, the control unit 6 calls the basic cam map from the storage unit 65 according to the operating state (step S14), and the valve timing command unit 64 operates so as to operate according to the basic cam map. , 4 (step S13). By this operation command, the opening / closing timing of the valves 30 and 40 is adjusted according to the basic cam map (see FIGS. 3A to 3D).

  If the difference in any one of the VVTs is outside the predetermined range, it can be said that any one of the VVTs is abnormal, and the abnormality determination unit 62 determines that there is an abnormality. When it is determined that one of the VVTs is abnormal, the control unit 6 determines whether the phase of the cam operated by the abnormal VVT is the advance side or the retard side from the normal time. This determination can be made by comparing the above-described calculated value with the basic cam map. Depending on the determination result, the shift amount corresponding to the fixing phase θ in the current operating state is called from the storage unit 65 (step S12), and the valve timing command unit 64 An operation command is issued to the normal VVT so that the normal cam is displaced by the selected shift amount on the retard side (step S13). By this operation command, the opening / closing timing of the valves 30 and 40 is adjusted so as to be shifted from the normal time to the advance side or the retard side by the shift amount as described above (see FIGS. 4C and 4D, etc.). ).

(effect)
When it is determined that there is an abnormality in one of the VVTs, the control device 1 for the internal combustion engine according to the first embodiment displaces the cam phase by a shift amount corresponding to the fixing phase in the operation state at that time than in the normal state. Then, the other VVT that is normal is operated. Therefore, the control device 1 is less likely to misfire, can improve the deterioration of combustion, and can reduce the deterioration of exhaust gas.

  In particular, the internal combustion engine 2 of this example performs a mirror cycle, but even when the ExVVT 4 is fixed on the retard side, the other VVT that is normal so as to reduce the overlap at the time of high load and high rotation is reduced. By operating (FIG. 4 (d)), exhaust gas does not become excessive and misfire is difficult. For this reason, the control device 1 can stabilize the combustion by increasing the compression ratio to some extent while effectively reducing the deterioration of the exhaust gas.

[Modification]
For example, at least one of the following modifications can be made to the control device for an internal combustion engine according to the first embodiment.
(1) The present invention is applied to an internal combustion engine other than an internal combustion engine that performs a mirror cycle.
(2) Both VVTs are hydraulic, or both VVTs are electric.

  The control device for an internal combustion engine of the present invention can be used for control of an internal combustion engine including both an intake side variable valve timing mechanism and an exhaust side variable valve timing mechanism.

DESCRIPTION OF SYMBOLS 1 Control apparatus of an internal combustion engine 2 Internal combustion engine 20 Cylinder block 20B Cylinder bore 20P Piston 20C Crankshaft 22 Cylinder head 22C Combustion chamber 223 Intake port 224 Exhaust port 24 Cylinder head cover 26 Crank angle sensor 3 Intake side variable valve timing mechanism (InVVT)
30 intake valve 30C intake side camshaft 32 electric motor 34 phase change mechanism 36 intake side cam angle sensor a motor shaft d eccentric shaft p planetary gear r ring gear s sprocket 4 exhaust side variable valve timing mechanism (ExVVT)
40 Exhaust Valve 40C Exhaust Side Cam Shaft 41 Case 42 Vane 46 Exhaust Side Cam Angle Sensor 5 Spark Plug 6 Control Unit (ECU)
60 Cam Angle Calculation Unit 62 Abnormality Determination Unit 64 Valve Timing Command Unit 65 Storage Unit 8 Injector 93 Intake Manifold 94 Exhaust Manifold

Claims (1)

An intake-side variable valve timing mechanism that changes the phase of the intake-side cam that opens and closes the intake valve, an exhaust-side variable valve timing mechanism that changes the phase of the exhaust-side cam that opens and closes the exhaust valve, and these are operated in conjunction with each other A control device for an internal combustion engine including a control unit for controlling,
The controller is
A cam angle calculation unit for calculating the phase of the intake side cam and the phase of the exhaust side cam;
An abnormality determination unit that determines whether there is an abnormality in the intake-side variable valve timing mechanism and the exhaust-side variable valve timing mechanism based on the calculated phases of both cams;
When the abnormality determining unit determines that there is an abnormality in one of the variable valve timing mechanisms, depending on the phase calculated by the cam angle calculation unit in the cam operated by the one variable valve timing mechanism having the abnormality And the other variable valve to displace the normal cam in a state shifted to the same side as the state shifted from the normal time to the advance side or the retard side in the phase of the cam on the abnormal side. A control device for an internal combustion engine, comprising: a valve timing command unit that commands an operation to a timing mechanism.

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