JP2006170011A - Valve characteristic control device for internal combustion engine - Google Patents

Abstract

A valve characteristic control device for an internal combustion engine capable of improving the responsiveness while ensuring the stability of the drive control of a variable valve mechanism at a low temperature of the engine is provided.
The drive of the variable valve mechanism is controlled by a control valve that adjusts the amount of fluid supplied to the pressure chamber. When the valve characteristic is changed to the target value through the driving of the variable valve mechanism, if the deviation ΔVTex between the target value and the actual value of the valve characteristic exceeds the determination value α (S120: YES), the control valve drive signal Is set to “100%”, and the exhaust side variable valve mechanism is forcibly driven (S110). After the deviation ΔVTex becomes equal to or smaller than the determination value α (S120: NO), the inching control in which the exhaust valve duty ratio DRex is alternately switched between “100%” and “50%” is performed. (S130).
[Selection] Figure 2

Description

  The present invention relates to a valve characteristic control device for an internal combustion engine.

  A variable valve mechanism that changes valve characteristics (valve timing, valve lift amount, etc.) of an engine valve such as an intake valve or an exhaust valve is known for the purpose of improving engine output and emission.

  Such a variable valve mechanism is feedback-controlled based on the deviation between the actual value of the valve characteristic and the target value so that the valve characteristic becomes a target value set based on the engine operating state. Here, in a variable valve mechanism driven using hydraulic pressure, the drive speed decreases when the oil temperature is low, such as when the engine is cold (during cold), so feedback control is performed in such a situation. If this happens, hunting and overshooting are likely to occur, and the controllability of the variable valve mechanism may become unstable.

Therefore, in the apparatus described in Patent Document 1, inching control is performed as a control mode of the variable valve mechanism at a low temperature of the engine or the like. In this inching control, the variable valve mechanism is repeatedly forcibly driven and stopped so that the variable valve mechanism moves toward the target value while repeating fine movement. In this inching control, the actual value of the valve characteristic gradually approaches the target value, so that hunting and overshoot are unlikely to occur, and the controllability of the variable valve mechanism is stabilized.
JP 2003-254017 A

  By the way, in the inching control, since the actual value of the valve characteristic gradually approaches the target value, the change speed of the valve characteristic becomes slow. Therefore, as in the apparatus described in Patent Document 1, when the inching control is performed from the start of the change to the completion of the change when the valve characteristic is changed, the responsiveness of the drive control of the variable valve mechanism decreases. Will occur.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a valve for an internal combustion engine that can improve the responsiveness while ensuring the stability of the drive control of the variable valve mechanism at a low temperature of the engine. It is to provide a characteristic control device.

In the following, means for achieving the above object and its effects are described.
The invention according to claim 1 is a valve characteristic control device for an internal combustion engine that controls driving of a variable valve mechanism that is driven by fluid supply to a pressure chamber and changes the valve characteristic of the engine valve. When changing the valve characteristic toward the target value, the variable valve mechanism is forcibly driven until the deviation between the target value and the actual value of the valve characteristic is equal to or less than the determination value, and the deviation is equal to or less than the determination value. The gist of the present invention is that it includes forcible drive means for changing the drive control of the variable valve mechanism to inching control in which the variable valve mechanism repeats forced drive and drive suspension.

  In this configuration, the variable valve mechanism is forcibly driven until the deviation between the target value and actual value of the valve characteristic falls below the judgment value, so the actual value of the valve characteristic is quickly changed to near the target value. The Therefore, as compared with the case where the inching control is performed from the start of the change to the completion of the change when the valve characteristic is changed as in the conventional device, the responsiveness of the drive control of the variable valve mechanism can be improved. It becomes like this.

  Since the drive control of the variable valve mechanism after the actual value of the valve characteristic is changed to near the target value is changed to the inching control as described above, the stability of the drive control is also ensured.

  Further, even in a situation where the temperature of the fluid is low, such as when the engine is cold, in this configuration, the variable valve mechanism is forcibly driven until the deviation becomes equal to or less than the determination value. The drive control of the variable valve mechanism is changed to inching control. Therefore, the actual value of the valve characteristic can be reliably changed to the target value even when the engine temperature is low.

  Therefore, according to the above configuration, it is possible to improve the responsiveness while ensuring the stability of the drive control of the variable valve mechanism at the time of engine low temperature. Incidentally, when the variable valve mechanism is forcibly driven, the responsiveness can be preferably improved by setting the drive parameter so that the change speed of the valve characteristic is maximized.

  Incidentally, as described in Patent Document 1, even if the forcible driving time (the time for forcibly driving the variable valve mechanism) is set in advance according to the magnitude of the deviation at the start of changing the valve characteristics, Although it is possible to quickly change the actual value to near the target value, in this case, there is a concern that the following problems may occur. In other words, the amount of change in the valve characteristics during forced drive can change due to various factors (deviation between the map fit value for setting the forced drive time based on the deviation and the actual optimum value, fluid temperature change, etc.) There is sex. Therefore, when the forced drive time is set in advance and the amount of change in the valve characteristics during forced drive is insufficient, the deviation after completion of forced drive is not so small. May not be a target deviation (deviation corresponding to the determination value).

  On the other hand, in the configuration according to the first aspect, the variable valve mechanism is forcibly driven until the deviation becomes equal to or less than the determination value. Deviation), and this makes it possible to improve the response compared to the conventional apparatus.

  According to a second aspect of the present invention, in the valve characteristic control device according to the first aspect, the variable valve mechanism is a mechanism whose drive is controlled by a control valve that adjusts a fluid supply amount to the pressure chamber. The forcible drive means holds the control valve drive signal as a signal corresponding to the forcible drive until the deviation is less than or equal to the determination value, and the drive signal after the deviation is less than or equal to the determination value. The gist of this is to alternately switch between a signal corresponding to the forced driving and a signal corresponding to the driving suspension.

  According to this configuration, the control valve drive signal is held at the signal corresponding to the forced drive until the deviation between the target value and the actual value of the valve characteristic is equal to or less than the determination value. It becomes possible to forcibly drive. Further, the drive signal after the deviation becomes equal to or less than the determination value is alternately switched between a signal corresponding to forced driving and a signal corresponding to driving suspension. Therefore, the variable valve mechanism comes to the target value while repeating the fine movement, so that the inching operation can be surely performed.

  According to a third aspect of the present invention, in the valve characteristic control device for an internal combustion engine according to the first or second aspect, the variable valve mechanism is a mechanism for changing a valve timing of an exhaust valve, and the valve timing is retarded. The gist of the invention is that the driving of the variable valve mechanism at the time of changing to is controlled by the forcible driving means.

  When the valve timing of the exhaust valve is changed to the retard side to increase the valve overlap amount, the exhaust discharged into the exhaust passage is again sucked into the combustion chamber, so that the unburned HC contained in the exhaust (Hydrocarbon) can be combusted in the next combustion stroke, so that the amount of HC emission can be reduced. Here, when the responsiveness of the variable valve mechanism is low, the valve timing cannot be retarded promptly, and thus the HC reduction effect as described above cannot be obtained for a while. In this regard, according to the above configuration, the valve timing of the exhaust valve can be quickly retarded, so that the effect of reducing HC can be obtained quickly.

  When the engine is cold-started, the HC emission amount tends to increase. Therefore, according to the invention described in claim 4, when the engine is cold-started, the valve timing is changed to the retard side, so that the amount of HC discharged at the time of cold-starting the engine is reduced. Can be suitably reduced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying a valve characteristic control device for an internal combustion engine according to the present invention will be described below in detail with reference to FIGS.
FIG. 1 shows a schematic configuration of a gasoline engine 1 to which a valve characteristic control device for an internal combustion engine according to the present embodiment is applied.

  The cylinder block 2 of the gasoline engine 1 includes a plurality of cylinders 3. A piston 4 provided in the cylinder 3 is connected to a crankshaft 5 via a connecting rod 6. The connecting rod 6 converts the reciprocating motion of the piston 4 into the rotational motion of the crankshaft 5.

  A cylinder head 7 is attached to the upper part of the cylinder block 2. In the cylinder 3, a combustion chamber 8 is formed between the upper end of the piston 4 and the cylinder head 7. The cylinder head 7 is provided with an injector 16 and a spark plug 11 that directly inject fuel into the combustion chamber 8. An intake port 12 and an exhaust port 13 provided corresponding to the combustion chamber 8 are connected to an intake passage 14 and an exhaust passage 15, respectively.

  An intake valve 17 and an exhaust valve 18 provided corresponding to the combustion chamber 8 open and close the intake port 12 and the exhaust port 13, respectively. The intake valve 17 and the exhaust valve 18 are opened and closed by rotation of cams (not shown) provided on the intake camshaft 31 and the exhaust camshaft 32 in accordance with the rotation of the intake camshaft 31 and the exhaust camshaft 32, respectively. Operate. The timing pulleys 33 and 34 provided at the tips of the intake camshaft 31 and the exhaust camshaft 32 are drivingly connected to the crankshaft 5 via a timing belt 35. When the crankshaft 5 rotates twice, each timing pulley 33 is connected. , 34 is rotated once. During operation of the gasoline engine 1, the rotational force of the crankshaft 5 is transmitted to the intake camshaft 31 and the exhaust camshaft 32 via the timing belt 35 and the timing pulleys 33 and 34. Thus, the intake valve 17 and the exhaust valve 18 are driven to open and close at a predetermined timing in synchronization with the rotation of the crankshaft 5, that is, corresponding to the reciprocating movement of each piston 4.

  A crank angle sensor 41 is provided in the vicinity of the crankshaft 5. The crank angle sensor 41 detects the rotational phase (crank angle) of the crankshaft 5 and detects the engine rotational speed NE of the gasoline engine 1 (crankshaft 5) based on the detection result. An intake side cam angle sensor 42 a is provided in the vicinity of the intake cam shaft 31, and the rotational phase (cam angle) of the intake cam shaft 31 is based on the output signals of the intake side cam angle sensor 42 a and the crank angle sensor 41. ) Is detected. Similarly, an exhaust side cam angle sensor 42 b is provided in the vicinity of the exhaust cam shaft 32, and the rotational phase (cam) of the exhaust cam shaft 32 is determined based on the output signals of the exhaust side cam angle sensor 42 b and the crank angle sensor 41. Corner) is detected.

  A high voltage output from an igniter is applied to the spark plug 11. The ignition timing of the spark plug 11 is determined by the high voltage output timing from the igniter. The gasoline engine 1 ignites an air-fuel mixture composed of intake air from the intake passage 14 and fuel injected from the injector 16 with the spark plug 11 and explodes in the combustion chamber 8 to obtain engine output. Further, the combustion gas generated at this time is discharged to the exhaust passage 15 and purified by the catalyst 70.

  A surge tank 51 for suppressing intake air pulsation is provided in a part of the intake passage 14. A throttle valve 53 whose opening degree is changed based on the operation of an accelerator pedal is provided on the upstream side of the surge tank 51. By changing the opening degree of the throttle valve 53, the throttle valve 53 is sucked into the combustion chamber 8. The amount of air to be adjusted is adjusted. A throttle opening sensor 54 for detecting the opening of the throttle valve 53 is attached in the vicinity of the throttle valve 53. Further, on the upstream side of the throttle valve 53, an air flow meter 55 that provides an output corresponding to the intake air amount Qa taken into the gasoline engine 1 is provided.

  In the present embodiment, a timing pulley 33 provided on the intake camshaft 31 is provided with an intake valve timing variable mechanism 60a which is a variable valve mechanism. The timing pulley 34 provided on the exhaust camshaft 32 is also provided with an exhaust valve timing variable mechanism 60b which is a variable valve mechanism.

  The intake valve timing variable mechanism 60a continuously changes the valve timing, which is the valve characteristic of the intake valve 17, by changing the relative rotational phase of the timing pulley 33 and the intake camshaft 31 with respect to the crankshaft 5 by the action of hydraulic pressure. It is a mechanism to change. Further, the variable exhaust valve timing mechanism 60b continuously changes the valve timing which is the valve characteristic of the exhaust valve 18 by changing the relative rotational phase of the timing pulley 34 and the exhaust camshaft 32 with respect to the crankshaft 5 by the action of hydraulic pressure. It is a mechanism to change to.

  The intake valve timing variable mechanism 60a includes an advance side pressure chamber for advancing the relative rotational phase of the intake camshaft 31 with respect to the timing pulley 33 and a retard side pressure chamber for delaying the relative rotational phase. The advance side pressure chamber is supplied with lubricating oil as a fluid through the advance side hydraulic passage P1a, and the retard side pressure chamber is supplied through the retard side hydraulic passage P2a. Similarly, the exhaust valve timing variable mechanism 60b includes an advance side pressure chamber for advancing the relative rotational phase of the exhaust camshaft 32 with respect to the timing pulley 34 and a retard side pressure chamber for delaying the relative rotational phase. Lubricating oil is supplied to the advance side pressure chamber through the advance side hydraulic passage P1b and to the retard side pressure chamber through the retard side hydraulic passage P2b.

  The lubricating oil stored in the oil pan 65 is sucked by the oil pump 62, and the sucked lubricating oil is supplied to oil control valves (hereinafter referred to as OCV) 63a and 63b by the oil pump 62. These OCVs 63a and 63b are linear solenoid valves provided with spool valves, which change the drive signal to the built-in electromagnetic solenoid, more specifically, by changing the duty ratio DR of the voltage to be applied. The supply destination and supply amount can be changed.

  The lubricating oil supplied to the OCV 63a is supplied to either the advance side hydraulic passage P1a or the retard side hydraulic passage P2a, and the oil is selectively supplied to each hydraulic passage, whereby the intake air to the crankshaft 5 is sucked. The relative rotation phase of the camshaft 31 is changed, so that the valve timing of the intake valve 17 is changed. More specifically, when the intake-side duty ratio DRin, which is the duty ratio of the drive signal of the OCV 63a, is close to “50%”, the advance-side hydraulic passage P1a and the retard-side hydraulic passage P2a are closed, whereby the intake valve The drive of the timing variable mechanism 60a is stopped, and the valve timing of the intake valve 17 is held at the current value. Further, when the intake side duty ratio DRin becomes larger than the vicinity of “50%”, the lubricating oil is supplied to the advance side hydraulic passage P1a, and the intake valve timing variable mechanism 60a is driven to the advance side, and thus the intake valve. The valve timing of 17 is changed to the advance side. At this time, as the intake-side duty ratio DRin increases, the flow rate of the lubricating oil increases, and the drive speed of the intake valve timing variable mechanism 60a toward the advance side increases. On the other hand, when the intake-side duty ratio DRin becomes smaller than the vicinity of “50%”, the lubricating oil is supplied to the retarded-side hydraulic passage P2a, and the intake valve timing variable mechanism 60a is driven to the retarded side. The valve timing 17 is changed to the retard side. Also at this time, as the intake-side duty ratio DRin decreases, the flow rate of the lubricating oil increases, and the drive speed of the intake valve timing variable mechanism 60a toward the retard side increases.

  Similarly, the lubricating oil supplied to the OCV 63b is supplied to either the advance side hydraulic passage P1b or the retard side hydraulic passage P2b, and the oil is selectively supplied to each hydraulic passage, whereby the crankshaft. 5 is changed, and the valve timing of the exhaust valve 18 is changed. More specifically, when the exhaust-side duty ratio DRex, which is the duty ratio of the drive signal of the OCV 63b, is close to “50%”, the advance-side hydraulic passage P1b and the retard-side hydraulic passage P2b are closed, thereby the exhaust valve. The drive of the timing variable mechanism 60b is stopped, and the valve timing of the exhaust valve 18 is maintained at the current value. When the exhaust-side duty ratio DRex becomes larger than the vicinity of “50%”, the lubricating oil is supplied to the retarded-side hydraulic passage P2b, and the exhaust valve timing variable mechanism 60b is driven to the retarded side. The valve timing of 18 is changed to the retard side. At this time, the flow rate of the lubricating oil increases as the exhaust side duty ratio DRex increases, and the drive speed of the exhaust valve timing variable mechanism 60b to the retard side increases. On the other hand, when the exhaust side duty ratio DRex becomes smaller than the vicinity of “50%”, the lubricating oil is supplied to the advance side hydraulic passage P1b, and the exhaust valve timing variable mechanism 60b is driven to the advance side, and thus the exhaust valve. The valve timing of 18 is changed to the advance side. Also at this time, the flow rate of the lubricating oil increases as the exhaust side duty ratio DRex decreases, and the drive speed of the exhaust valve timing variable mechanism 60b toward the advance side increases.

  Various controls such as ignition timing control of the gasoline engine 1, fuel injection amount control, or valve timing control based on phase control of each valve timing mechanism are performed by a control device (hereinafter referred to as ECU) 80. The control device 80 is configured around a microcomputer including a central processing control device (CPU). For example, the control device 80 is provided with a read-only memory (ROM) in which various programs, maps, and the like are stored in advance, and a random access memory (RAM) in which CPU calculation results and the like are temporarily stored. The control device 80 is also provided with a backup RAM, an input interface, an output interface, and the like for storing calculation results and prestored data after the engine is stopped. Output signals from the crank angle sensor 41, the intake side cam angle sensor 42a, the exhaust side cam angle sensor 42b, the water temperature sensor 43 for detecting the cooling water temperature, the throttle opening sensor 54, the air flow meter 55, and the like are used as the input interface. To be entered through. The operating state of the gasoline engine 1 is detected by the output signals of these sensors 41 to 43, 54, 55 and the like.

On the other hand, the output interface is connected to the injector 16, the igniter for the spark plug 11, the OCV 63a, the OCV 63b, and the like via corresponding drive circuits.
The control device 80 is based on the signals from the sensors 41 to 43, 54, 55, etc., and in accordance with the control program and initial data stored in the ROM, the injector 16, igniter, OCV 63a (intake valve timing variable mechanism 60a). ), OCV 63b (exhaust valve timing variable mechanism 60b), and the like are suitably controlled.

  The control device 80 performs valve timing control of the intake valve 17 through drive control of the intake valve timing variable mechanism 60a. In such valve timing control of the intake valve 17, the intake valve timing variable mechanism 60a is driven so that the actual valve timing of the intake valve 17 becomes the target valve timing set based on the engine operating state. Here, the intake side actual displacement angle VTin, which is the actual displacement angle of the intake camshaft 31, is used as the actual valve timing of the intake valve 17, and the target displacement angle of the intake camshaft 31 is used as the target valve timing of the intake valve 17. The intake side target displacement angle VTTin is used. The intake side duty ratio DRin is variably set in accordance with the deviation ΔVTin between the intake side actual displacement angle VTin and the intake side target displacement angle VTTin, and the drive of the intake valve timing variable mechanism 60a is feedback-controlled, so that the intake valve The valve timing 17 is quickly adjusted to the target valve timing.

  Similarly, the control device 80 performs valve timing control of the exhaust valve 18 through drive control of the exhaust valve timing variable mechanism 60b. In such valve timing control of the exhaust valve 18, the exhaust valve timing variable mechanism 60b is driven so that the actual valve timing of the exhaust valve 18 becomes a target valve timing set based on the engine operating state. Here, the exhaust side actual displacement angle VTex, which is the actual displacement angle of the exhaust camshaft 32, is used as the actual valve timing of the exhaust valve 18, and the target displacement angle of the exhaust camshaft 32 is used as the target valve timing of the exhaust valve 18. The exhaust side target displacement angle VTTex is used. Then, the exhaust side duty ratio DRex is variably set according to the deviation ΔVTex between the exhaust side actual displacement angle VTex and the exhaust side target displacement angle VTTex, and the drive of the exhaust valve timing variable mechanism 60b is feedback-controlled, whereby the exhaust valve The valve timing 18 is quickly adjusted to the target valve timing.

  The displacement angle used in each valve timing control described above is a value representing the relative rotational phase of the camshaft with respect to the crankshaft, and the change angle is converted to a crank angle (° CA). The intake side actual displacement angle VTin is obtained based on detection signals from the crank angle sensor 41 and the intake side cam angle sensor 42a. The intake side actual displacement angle VTin is set to “0 ° CA” when the valve timing of the intake valve 17 is retarded to the maximum, and the valve timing of the intake valve 17 is determined from the maximum retard timing. It is a value indicating whether or not it is advanced. Further, the exhaust side actual displacement angle VTex is obtained based on detection signals from the crank angle sensor 41 and the exhaust side cam angle sensor 42b. The exhaust side actual displacement angle VTex is set to “0 ° CA” when the valve timing of the exhaust valve 18 is advanced to the maximum, and the valve timing of the exhaust valve 18 is determined from this maximum advance timing. It is a value that represents how much retarded.

  On the other hand, in the gasoline engine 1 in the present embodiment, rapid warm-up control of the catalyst is performed so that the exhaust gas purification performance of the catalyst 70 can be exerted at an early stage when the engine is cold-started. In this catalyst rapid warm-up control, the exhaust temperature is increased by implementing fuel injection in the compression stroke, increasing the fuel injection amount by increasing the intake air amount, and retarding the ignition timing. I try to activate it early. Further, when this catalyst rapid warm-up control is executed, in order to reduce the amount of HC discharged into the exhaust passage at the same time, the air-fuel ratio of the air-fuel mixture is made lean to promote the oxidation of unburned HC and the exhaust gas The valve timing of the valve 18 is retarded. Thus, if the valve timing of the exhaust valve 18 is retarded to increase the valve overlap amount, the exhaust discharged into the exhaust passage 15 is again sucked into the combustion chamber 8 and is therefore included in the exhaust. Unburned HC can be burned in the next combustion stroke, so that the amount of HC emission can be reduced. In addition, when the valve timing of the exhaust valve 18 that is implemented in conjunction with the execution of the catalyst rapid warm-up control in this way, the combustion state in the engine and the deterioration of the exhaust properties can be suppressed as much as possible. The exhaust side target displacement angle VTTex is set based on the engine operating state so that the retard amount becomes large.

  Here, when the engine temperature is low, such as during cold start, the oil temperature is low and the viscosity of the lubricating oil is high, so that the operating speed of the OCV 63b is reduced and the flow speed of the lubricating oil is reduced. For example, the driving speed of the exhaust valve timing variable mechanism 60b is decreased. Therefore, if feedback control is performed on the drive of the exhaust valve timing variable mechanism 60b in such a situation, hunting or overshooting is likely to occur, and the controllability of the mechanism may become unstable.

  On the other hand, when the engine temperature is low and the control for repeatedly finely moving the exhaust valve timing variable mechanism 60b by repeatedly forcibly driving and stopping the drive, so-called inching control is performed, the valve timing is a little. Since it goes to the target value one by one, hunting and overshoot are unlikely to occur, and the controllability of the mechanism becomes stable. However, in the operation by this inching control, so-called inching operation, the valve timing of the exhaust valve 18 gradually approaches the target value, so that the changing speed becomes slow. Therefore, when the inching control is performed from the start of the change to the completion of the change when the valve timing is changed, the time until the actual value reaches the target value becomes longer, and the drive control of the exhaust valve timing variable mechanism 60b is increased. The malfunction that the responsiveness falls will arise. If the responsiveness of the exhaust valve timing variable mechanism 60b is lowered in this way, the valve timing of the exhaust valve 18 cannot be retarded promptly, and there is a problem that the effect of reducing HC cannot be obtained quickly. Become.

  Therefore, in the present embodiment, the exhaust valve timing variable mechanism 60b is provided with a forcible drive means for changing the forcible drive mode, and by performing the duty ratio setting process during rapid catalyst warm-up described below, the engine The responsiveness of the drive control of the exhaust valve timing variable mechanism 60b at low temperatures is improved while ensuring its stability. By improving the responsiveness, the valve timing of the exhaust valve 18 is quickly retarded when the engine is cold-started, so that the effect of reducing HC can be obtained quickly.

  FIG. 2 shows a procedure for the duty ratio setting process at the time of rapid catalyst warm-up executed by the control device 80. Note that this processing is repeatedly executed during the start of the engine and during the execution of the catalyst rapid warm-up control.

  When this processing is started, first, the exhaust side target displacement angle VTTex is set to the most retarded angle position, that is, the exhaust gas is exhausted to a displacement angle corresponding to the maximum retarded angle position within the movable range of the exhaust valve timing variable mechanism 60b. It is determined whether or not the side target displacement angle VTTex is set (S100). When the exhaust side target displacement angle VTTex is set to the most retarded position (S100: YES), the exhaust side duty ratio DRex is set to “100%” (S110), and the exhaust valve timing variable mechanism is set. 60b is driven to the retard side at the maximum speed. And this process is once complete | finished. At this time, since the exhaust valve timing variable mechanism 60b is driven to the maximum retard position within the movable range, the valve timing of the exhaust valve 18 is naturally changed to the most retard position through this drive.

  On the other hand, if the exhaust side target displacement angle VTTex is not set to the most retarded position (S100: NO), the deviation ΔVTex between the exhaust side target displacement angle VTTex and the exhaust side actual displacement angle VTex at the execution timing of this process. Is determined to exceed the determination value α (S120). In the present embodiment, the determination value α is set to “5 ° CA”, but other values may be set as appropriate.

  When it is determined that the deviation ΔVTex exceeds the determination value α (S120: YES), since the deviation ΔVTex is large, if the drive control of the exhaust valve timing variable mechanism 60b is performed with the inching control as it is, There is a possibility that the valve timing of the exhaust valve 18 cannot be quickly retarded to the target value. That is, there is a possibility that the effect of reducing HC cannot be obtained quickly. Therefore, when judged in this way, the exhaust side duty ratio DRex is set to “100%” (S110), the exhaust valve timing variable mechanism 60b is forcibly driven to the retard side at the maximum speed, and this processing is Once terminated. Then, this process is repeatedly executed, and the exhaust-side duty ratio DRex is held at “100%” that is a forced drive signal until the deviation ΔVTex becomes equal to or smaller than the determination value α. Therefore, the exhaust valve timing varying mechanism 60b is continuously forcedly driven until a negative determination is made in step S120.

  On the other hand, when it is determined that the deviation ΔVTex is equal to or smaller than the determination value α (S120: NO), since the deviation ΔVTex is sufficiently small, the drive control of the exhaust valve timing variable mechanism 60b is performed by inching control. The valve timing of the exhaust valve 18 can be quickly retarded to the target value, and the effect of reducing HC can also be obtained quickly. Therefore, when it is determined in this way, the inching flag INF indicating permission to execute the inching control is set to “1”, and the inching control is executed (S130). And this process is once complete | finished.

  In this inching control, during the drive stop time Tr, a drive stop signal (exhaust-side duty ratio DRex = 50%) is input to the OCV 63b, and the drive of the exhaust valve timing variable mechanism 60b is stopped. When the drive suspension time Tr elapses, a forced drive signal (exhaust-side duty ratio DRex = 100%) is input to the OCV 63b during the forced drive time Tc, and the exhaust valve timing variable mechanism 60b is forcibly driven. By alternately switching between the forced drive signal and the drive stop signal, the exhaust valve timing variable mechanism 60b is intermittently forcedly driven, and the mechanism is directed toward the target value while repeating fine movement. When the exhaust side actual displacement angle VTex becomes the exhaust side target displacement angle VTTex, the drive pause signal is input to the OCV 63b, and the change of the valve timing of the exhaust valve 18 is completed.

  In the present embodiment, the forcible driving time Tc and the driving suspension time Tr are variably set according to the deviation ΔVTex in the execution timing of the duty ratio setting process, but these values are fixed in advance. It may be a value.

Next, how the exhaust side actual displacement angle VTex is changed through execution of the duty ratio setting process will be described with reference to FIG.
When the engine is cold-started and the catalyst rapid warm-up control as described above is started, the exhaust side target displacement angle VTTex is set to the retard side in order to retard the valve timing of the exhaust valve 18 at the same time. It is set (time t1). As described above, when the exhaust side target displacement angle VTTex is set to the retard side, the deviation ΔVTex increases. Therefore, a forced drive signal (exhaust side duty ratio DRex = 100%) is input to the OCV 63b, and the deviation ΔVTex is determined. This forced drive signal is held until the value α is reached or less (time t2).

  When the inching flag INF is set to “1” at time t2, inching control is started. That is, during the drive suspension time Tr, the exhaust-side duty ratio DRex is set to “50%” and the drive of the exhaust valve timing variable mechanism 60b is suspended. When the drive suspension time Tr elapses, the exhaust-side duty ratio DRex is set to “100%” and the exhaust valve timing variable mechanism 60b is forcibly driven during the forced drive time Tc. By alternately switching between the forced drive signal and the drive stop signal, the exhaust side actual displacement angle VTex is gradually changed toward the exhaust side target displacement angle VTTex, and the exhaust side actual displacement angle VTex is exhausted. When the side target displacement angle VTTex is reached (time t3), the exhaust side duty ratio DRex is maintained at “50%”.

  After that, when the rapid catalyst warm-up control is finished (time t4), the inching flag INF is set to “0”, and the valve timing of the exhaust valve 18 is changed to a timing according to the engine operating state at that time. The

  As described above, in the duty ratio setting process according to the present embodiment, the exhaust valve timing variable mechanism 60b is forcibly driven until the deviation ΔVTex between the exhaust side target displacement angle VTTex and the exhaust side actual displacement angle VTex becomes equal to or smaller than the determination value α. In this way (time t1 to time t2), the exhaust side actual displacement angle VTex is quickly changed to the vicinity of the exhaust side target displacement angle VTTex. Therefore, as compared with the case where the inching control is performed from the start of the change to the completion of the change when the valve characteristic is changed as in the above-described conventional device, the response of the drive control of the exhaust valve timing variable mechanism 60b is improved. It becomes like this.

  Then, the drive control of the exhaust valve timing variable mechanism 60b after the exhaust side actual displacement angle VTex is changed to the vicinity of the exhaust side target displacement angle VTTex (after time t2) is changed to the inching control as described above. Therefore, the stability of the drive control is also ensured.

  Even when the temperature of the lubricating oil is low, such as when the engine is cold, the exhaust valve timing variable mechanism 60b is forcibly driven until the deviation ΔVTex becomes equal to or less than the determination value α, and the deviation ΔVTex is equal to or less than the determination value α. Then, the drive control of the mechanism is changed to inching control. Therefore, the exhaust side actual displacement angle VTex can be reliably changed to the exhaust side target displacement angle VTTex even when the engine temperature is low.

  The duty ratio setting process is executed when the valve timing of the exhaust valve 18 is retarded during a cold start of the engine where the amount of HC emission from the engine is likely to increase. As a result, the valve timing of the exhaust valve 18 is quickly retarded, so that the amount of HC discharged during the cold start of the engine is sufficiently reduced.

  Note that, as described in Patent Document 1, the forced drive time of the variable valve mechanism is set in advance in accordance with the deviation between the actual value of the valve characteristic and the target value and the deviation at the start of the change of the valve characteristic. Even if this is done, it is possible to quickly change the actual value of the valve characteristic to the vicinity of the target value, but in this case, there is a concern that the following problems may occur. In other words, the amount of change in the valve characteristics during forced drive can change due to various factors (deviation between the map fit value for setting the forced drive time based on the deviation and the actual optimum value, fluid temperature change, etc.) There is sex. Therefore, when the forced drive time is set in advance and the amount of change in the valve characteristics during forced drive is insufficient, the deviation after completion of forced drive is not so small. May not be a target deviation (deviation corresponding to the determination value α).

  On the other hand, in the present embodiment, the exhaust valve timing variable mechanism 60b is forcibly driven until the deviation ΔVTex becomes equal to or smaller than the determination value α, so that the actual deviation is reliably and promptly set to the target deviation (to the determination value α). This makes it possible to improve the responsiveness of the variable exhaust valve timing mechanism 60b as compared with the conventional apparatus.

As described above, according to the present embodiment, the following effects can be obtained.
(1) In the duty ratio setting process, when the valve timing of the exhaust valve 18 is changed toward the target value, the deviation ΔVTex between the exhaust side target displacement angle VTTex and the exhaust side actual displacement angle VTex becomes equal to or less than the determination value α. The exhaust valve timing variable mechanism 60b is forcibly driven to the maximum. Therefore, the exhaust side actual displacement angle VTex is quickly changed to the vicinity of the exhaust side target displacement angle VTTex, and the responsiveness of the drive control of the exhaust valve timing variable mechanism 60b can be improved. .

  In the duty ratio setting process, the exhaust valve timing variable mechanism 60b after the deviation ΔVTex becomes equal to or smaller than the determination value α, that is, after the exhaust-side actual displacement angle VTex is changed to the vicinity of the exhaust-side target displacement angle VTTex. This control mode is changed to inching control in which the exhaust valve timing variable mechanism 60b repeats forced driving and driving suspension. Therefore, the stability of the drive control of the exhaust valve timing variable mechanism 60b is also ensured.

  Further, as described above, the exhaust valve timing variable mechanism 60b is forcibly driven until the deviation ΔVTex becomes equal to or smaller than the determination value α, and when the deviation ΔVTex becomes equal to or smaller than the determination value α, the drive control of the mechanism is changed to inching control. ing. Therefore, even when the temperature of the lubricating oil is low, such as when the engine is cold, the actual value of the valve characteristics can be reliably changed to the target value.

  Therefore, by executing the duty ratio setting process, it is possible to improve the responsiveness while ensuring the stability of the drive control of the exhaust valve timing variable mechanism 60b when the engine temperature is low.

  (2) The exhaust valve timing variable mechanism 60b is a mechanism whose drive is controlled by an OCV 63b that adjusts the amount of lubricating oil supplied to each pressure chamber. In the duty ratio setting process, the OCV 63b drive signal is held as a signal corresponding to the forced drive of the exhaust valve timing variable mechanism 60b (the forced drive signal) until the deviation ΔVTex becomes equal to or smaller than the determination value α. . Further, after the deviation ΔVTex becomes equal to or less than the determination value α, the drive signal is alternately switched between the forced drive signal and a signal corresponding to the drive stop of the exhaust valve timing variable mechanism 60b (the drive stop signal). ing.

  Accordingly, the drive signal of the OCV 63b is held at the forced drive signal until the deviation ΔVTex between the exhaust side target displacement angle VTTex and the exhaust side actual displacement angle VTex becomes equal to or less than the determination value α, and the exhaust valve timing variable mechanism 60b is controlled. It becomes possible to perform forced driving reliably. The drive signal after the deviation ΔVTex is equal to or less than the determination value α is alternately switched between the forced drive signal and the drive suspension signal. For this reason, the exhaust valve timing varying mechanism 60b is directed toward the target value while repeating the fine movement, so that the inching operation can be reliably performed.

  (3) At the time of cold start of the engine in which the exhaust amount of HC increases, the valve timing of the exhaust valve 18 is changed to the retard side, and the duty control is performed for the drive control of the exhaust valve timing variable mechanism 60b at that time. The ratio setting process is executed. Therefore, the valve timing of the exhaust valve 18 can be quickly retarded, and hence the effect of reducing HC by increasing the valve overlap amount can be obtained quickly. As a result, the amount of HC discharged when the engine is cold started can be suitably reduced.

In addition, the said embodiment can also be changed and implemented as follows.
The duty ratio setting process is executed in conjunction with the catalyst rapid warm-up control, but the duty ratio is set at least when the valve timing of the exhaust valve 18 is changed to the retard side at the cold start of the engine. If the processing is executed, the same effect as the above embodiment can be obtained.

  ・ The above-mentioned duty ratio setting process is executed when the engine is cold-started so that the catalyst rapid warm-up control is performed. However, this process should also be executed when the engine is cold operating or after the warm-up is completed. Can do. Also in this case, the effects described in (1) and (2) above can be obtained.

  Although the exhaust-side duty ratio DRex of the forced drive signal is set to “100%”, other values can be set as long as the duty ratio can reliably drive the exhaust valve timing variable mechanism 60b. Further, although the exhaust side duty ratio DRex of the drive stop signal is set to “50%”, other values should be set as long as the duty ratio can reliably stop the drive of the exhaust valve timing variable mechanism 60b. You can also.

  In the above embodiment, the displacement angle is used as a value representing the valve timing of the exhaust valve 18. However, this is only an example, and other parameters representing the valve timing of the exhaust valve 18 may be used.

  The duty ratio setting process is performed when the valve timing of the exhaust valve 18 is changed to the advance side, when the valve timing of the intake valve 17 is changed to the retard side, or when the valve timing of the intake valve 17 is changed to the advance side. The same principle can be applied to the drive control of the variable valve mechanism at each phase change such as when changing. In these cases, the same effects as those described in the above (1) and (2) can be obtained.

  The variable valve mechanism is a mechanism that changes the valve timing of engine valves such as an intake valve and an exhaust valve. However, the variable valve mechanism to which the valve characteristic control device according to the present invention is applied is not limited to such a variable valve mechanism. For example, the present invention is also applicable to a variable valve mechanism that changes the lift amount and valve timing of an engine valve, and a variable valve mechanism that changes only the lift amount of an engine valve.

  In the above embodiment, the valve characteristic control device according to the present invention is applied to the gasoline engine 1. However, the internal combustion engine to be applied is not limited to the gasoline engine 1 at all. In short, if it is an internal combustion engine that is a mechanism driven by fluid supply to the pressure chamber and includes a variable valve mechanism that changes the valve characteristic of the engine valve, the valve characteristic control device according to the above embodiment and its modification is applied. Is possible.

1 is a schematic configuration diagram of a gasoline engine 1 to which a valve characteristic control device according to an embodiment is applied. The flowchart which shows the process sequence about the duty ratio setting in the embodiment. 6 is a timing chart showing how the valve characteristics are changed through execution of the duty ratio setting process in the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Gasoline engine, 2 ... Cylinder block, 3 ... Cylinder, 4 ... Piston, 5 ... Crankshaft, 6 ... Connecting rod, 7 ... Cylinder head, 8 ... Combustion chamber, 11 ... Spark plug, 12 ... Intake port, 13 ... Exhaust Port 14, intake passage 15, exhaust passage 16, injector 17, intake valve 18, exhaust valve 31, intake camshaft 32, exhaust camshaft 33, 34 timing pulley 35, timing belt DESCRIPTION OF SYMBOLS 41 ... Crank angle sensor, 42a ... Intake side cam angle sensor, 42b ... Exhaust side cam angle sensor, 43 ... Water temperature sensor, 51 ... Surge tank, 53 ... Throttle valve, 54 ... Throttle opening sensor, 55 ... Air flow meter, 60a ... Intake valve timing variable mechanism, 60b ... Exhaust valve timing variable mechanism, 62 ... Oil pump , 63a, 63 b ... oil control valve (OCV), 65 ... oil pan, 70 ... catalyst 80 ...... controller, P1a, P1b ... advance side hydraulic passage, P2a, P2b ... lag side hydraulic passage.

Claims (4)

In a valve characteristic control device for an internal combustion engine that controls driving of a variable valve mechanism that is driven by fluid supply to a pressure chamber and changes the valve characteristic of an engine valve.
When changing the valve characteristic toward the target value, the variable valve mechanism is forcibly driven until the deviation between the target value and the actual value of the valve characteristic is equal to or less than the determination value, and the deviation is equal to or less than the determination value. After that, a valve characteristic control device for an internal combustion engine, comprising: forcible drive means for changing drive control of the variable valve mechanism to inching control in which the variable valve mechanism repeats forced drive and drive suspension. In the valve characteristic control device according to claim 1,
The variable valve mechanism is a mechanism whose drive is controlled by a control valve that adjusts a fluid supply amount to the pressure chamber,
The forced drive means holds the control valve drive signal as a signal corresponding to the forced drive until the deviation is less than or equal to the determination value, and after the deviation is less than or equal to the determination value, A valve characteristic control device for an internal combustion engine, wherein a signal corresponding to the forced drive and a signal corresponding to the drive suspension are alternately switched. The variable valve mechanism is a mechanism that changes a valve timing of an exhaust valve, and driving of the variable valve mechanism when the valve timing is changed to a retard side is controlled by the forcible drive means. A valve characteristic control device for an internal combustion engine as described. The valve characteristic control device for an internal combustion engine according to claim 3, wherein the valve timing is changed to a retard side when the engine is cold-started.

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