JP2001336446A - Knocking controller of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the decrease of the operability accompanying the avoidance of knocking. SOLUTION: A knocking controller is provided with the operating angle change mechanism which changes the operating angle of an inlet valve and the phase change mechanism which change the center phase of this operating angle. For example in the first operating state in which an engine is in the idle area or R/L area and closed time (f) of the inlet valve is sparked advancely passing a bottom dead point, ignition timing is quickly lagged by the specified amount of retard ΔR1 when knocking is detected. Concurrently the center phase (d) is sparked advancely and operating angle (c) is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a knocking control device for suppressing knocking of a spark ignition type internal combustion engine typified by an automobile gasoline engine.
The present invention relates to a knocking control device for an internal combustion engine including both an operation angle changing mechanism and a phase changing mechanism of an intake valve.

[0002]

2. Description of the Related Art Knocking often occurs under high-temperature and high-load conditions, which are particularly severe conditions in use of an internal combustion engine. In other words, the temperature of the intake air itself rises due to heat exchange with the inner wall of the cylinder, the piston, etc., and while waiting for flame propagation in a compressed state, the unburned mixture spontaneously ignites, and the combustion speed rises abnormally high As a result, a specific knocking sound is generated, and the accelerated flame rapidly raises the local temperature of the piston, the valve, and the like with a high heat transfer coefficient, thereby lowering the durability. As described above, knocking is likely to occur due to an increase in the temperature of the compressed air-fuel mixture, but is particularly likely to occur when the cooling water temperature of the internal combustion engine is increasing due to a continuous high load state.

[0003] In order to avoid such knocking, it is most certain to set the compression ratio of the engine low.
Then, the thermal efficiency decreases and the fuel efficiency deteriorates. Therefore, in recent years, many gasoline engines for automobiles use a relatively high compression ratio, detect the occurrence of knocking with a knock sensor or the like, and retard the ignition timing when knocking occurs, thereby suppressing knocking. Achieving both high compression ratios.

However, avoiding knocking by retarding the ignition timing has good responsiveness and is suitable for avoiding knocking itself. On the other hand, however, deterioration of fuel efficiency due to delay of combustion start from the optimal timing, There are problems such as deterioration of the durability of the catalyst and the like due to an increase in the exhaust gas temperature.

[0005] In order to minimize such a problem caused by retardation of the ignition timing, for example, as disclosed in Japanese Patent Application Laid-Open No. 8-338295, to avoid knocking,
The phase of the camshaft on the intake side of the engine is variably controlled, and the phase of the camshaft is delayed with respect to the crankshaft when knocking occurs, in the form of a combination with the retard of the ignition timing. A knocking control device that reduces the compression ratio has been proposed. In other words, as the actual compression ratio is reduced by delaying the closing timing of the intake valve, the charging efficiency is also reduced, the temperature of the air-fuel mixture during compression is reduced, the rise in exhaust temperature is prevented, and knocking is suppressed. is there.

[0006]

The above-mentioned JP-A-8-33
As disclosed in US Pat. No. 8,295, the configuration in which the phase of the camshaft is changed to avoid knocking,
Since not only the closing timing of the intake valve but also the opening timing changes simultaneously by the same angle, the phase change amount is set relatively small and the opening timing of the intake valve changes in a narrow range near top dead center. If the closing timing is delayed by more than 20 ° CA to avoid knocking,
The opening timing of the intake valve is significantly delayed from the top dead center, and a decrease in torque cannot be ignored due to the occurrence of a pump loss due to the lack of intake at the beginning of the intake stroke.

Further, if the operating angle of the intake valve is set wide in advance in order to avoid the opening timing of the intake valve after the top dead center, an appropriate state is obtained at the timing retarded to avoid knocking. However, at normal valve timing without retarding to avoid knocking, the opening timing of the intake valve became much earlier than the top dead center, the valve overlap expanded, and the exhaust stroke increased. At the end of the period, high-temperature exhaust gas flows back to the intake side, causing the intake temperature to rise significantly. As a result, the conditions under which knocking occurs under normal valve timing are greatly deteriorated, and knocking is more likely to occur.

Further, when the valve overlap is large as described above, especially in an internal combustion engine equipped with a turbocharger, when the rotation speed of the turbocharger is in the process of increasing, such as during starting acceleration, the intake pressure ( When the supercharging pressure is still low and the exhaust pressure is significantly high, the concentration of residual gas in the cylinder suddenly increases, causing the problem that not only the charging efficiency but also the knock resistance deteriorate. appear.

As described above, in the conventional configuration in which the opening timing and the closing timing of the intake valve are delayed in the same phase simply by changing the phase of the camshaft on the intake valve side,
The effect of avoiding knocking is limited and not sufficient.

On the other hand, Japanese Patent Application Laid-Open No. 11-036 by the present applicant
Japanese Patent Application Laid-Open No. 906 proposes a knocking control device that effectively obtains the effect of avoiding knocking by combining it with an operating angle changing mechanism that can mainly enlarge or reduce the operating angle of the intake valve in order to avoid knocking. I have. However, when only such an operating angle changing mechanism is used, similarly to the case where only the phase changing mechanism is used as described in JP-A-8-338295, the closing timing of the intake valve is determined by the changing mechanism. When the phase is changed to the above-mentioned phase, the opening timing is inevitably determined, and there is a possibility that the opening timing is greatly deviated from a desired opening timing according to an operation state or the like.

By the way, the present applicant uses both an operating angle changing mechanism for changing the operating angle of the intake valve and a phase changing mechanism for changing the central phase (central angle) of the operating angle of the intake valve, and mainly achieves the fuel economy performance. A new intake valve drive control device has been proposed prior to this application with the aim of improving the operating range and expanding the range of use of the minimum operating angle.

The present invention provides a novel knocking control device when both the operating angle changing mechanism and the phase changing mechanism of the intake valve are used together. That is, one object of the present invention is not limited to simply combining the retardation of the center phase and the enlargement of the operating angle as a means for avoiding knocking, but also a new method using two changing mechanisms together as described later. It is to propose a concept of knock avoidance and a theory of control.

[0013]

According to a first aspect of the present invention, there is provided a knocking control apparatus for an internal combustion engine which changes an operating angle of an intake valve and a center phase of an operating angle of the intake valve. A phase changing mechanism, ignition timing changing means for changing ignition timing, knocking detecting means for detecting occurrence of knocking at a predetermined level, operating angle obtaining means for detecting or estimating an actual operating angle of the intake valve, Phase acquisition means for detecting or estimating the actual center phase of the valve, and when knocking is detected, based on the actual operating angle and actual center phase at this time, the ignition timing, the operating angle, and the central phase, respectively. Is maintained or variably controlled.

For example, when the engine is in an extremely low load range below a predetermined load including an idle range or in a constant speed (R / L) range, the closing timing (IVC) of the intake valve is advanced from the bottom dead center. First
When knocking is detected in the above operating state, preferably, the ignition timing is promptly retarded as in the invention according to claim 2. That is, the ignition timing can be generally retarded with good responsiveness, and knocking is quickly suppressed.

At the same time, in order to avoid the deterioration of fuel efficiency due to the retardation of the ignition timing, the operating angle and the center phase of the intake valve are maintained or variably controlled to prevent knocking due to the operating angle characteristic. I will replace it. Since the control of the operating angle and the center phase involves a mechanical delay,
The actual operating angle gradually changes depending on the operating speed of each actuator or the like. Specifically, the center phase of the intake valve is advanced so that the actual compression ratio (filling efficiency) of the intake valve is reduced.

More preferably, while keeping the opening timing (IVO) of the intake valve substantially constant as in the invention according to claim 3,
The operating angle is reduced according to the advance of the center phase so that the IVC is advanced to lower the actual compression ratio. As a result, the actual compression ratio decreases, and knocking does not easily occur. It should be noted that, under normal temperature conditions, an excessive decrease in the actual compression ratio causes deterioration of combustion, but under high temperature conditions in which knocking occurs, there is sufficient room to reduce the actual compression ratio.

On the other hand, when the engine is continuously operated in the moderate acceleration range, the opening timing of the intake valve is advanced more than the top dead center, and the intake valve is preferably advanced so as to minimize the pump loss. Is advanced more than the bottom dead center. In such a second operating state, the suction negative pressure is low,
Since the throttle valve is almost fully open,
If the actual compression ratio is reduced by advancing the IVC at the time of knocking, the charging efficiency is reduced and the acceleration capacity tends to be insufficient.

Therefore, when knock is detected in such a second operating state, securing the torque is the highest priority, so that the IVC is retarded so as to increase the actual compression ratio to secure the intake air amount. In addition, it is necessary to avoid knocking due to a large retardation of the ignition timing.

Therefore, in the invention according to claim 4, when knocking is detected in the second operating state, the center phase of the intake valve is retarded, and the ignition timing is gradually decreased according to the retardation of the center phase. Retard. Thereby, the closing timing is made closer to the bottom dead center to improve the charging efficiency (that is, the intake air amount is increased), and the ignition timing is further gradually changed to the retard side in accordance with the retardation of the center phase. Thereby, knocking can be avoided. At this time, since the valve overlap is reduced with the retardation of the opening timing of the intake valve, high-temperature residual gas is reduced, which is effective in avoiding knock.

However, for the purpose of maintaining the fuel efficiency improving effect even slightly, the operating angle is adjusted according to the retardation of the center phase so as to keep the valve overlap substantially constant, as in the invention according to claim 5. It may be enlarged.

In the third operating state in which the engine is in the low-speed high-load region and at least the closing timing of the intake valve is located near the bottom dead center, the actual compression ratio is very high (substantially the highest value) and Near the dead center, the sensitivity of the reduction of the actual compression ratio due to the retardation of the IVC is extremely low. Therefore, also in this case, it is difficult to avoid knocking only by retarding the IVC, and the ignition timing is retarded to quickly and surely avoid knocking, and after the retarding amount of the IVC takes effect, It is necessary to devise control such as recovering the ignition timing.

Therefore, in the invention according to claim 6, when knocking is detected in such a third operating state, the ignition timing is quickly retarded and the center phase is retarded. More preferably, as in the invention according to claim 7, the operating angle is increased in accordance with the retardation of the center phase so as to keep the opening timing of the intake valve substantially constant.

In the fourth operating state where the engine is in a high speed range and at least the closing timing of the intake valve is delayed more than the bottom dead center, the charging efficiency is near the maximum value, but the charging efficiency is close to the maximum value. Since the sensitivity of the reduction of the actual compression ratio is high, it is effective to minimize the retardation of the ignition timing at which the exhaust temperature rises high, and to avoid knocking mainly by retarding the IVC.

Therefore, when knocking is detected in the fourth operating state, the center phase of the intake valve is retarded as in the invention according to claim 8, and the knocking of the intake valve is detected as in the invention according to claim 9. The operating angle is increased in accordance with the retardation of the center phase so as to keep the opening timing substantially constant. If necessary, the ignition timing is promptly retarded as in the invention according to claim 10 in order to quickly avoid knocking.

Preferably, the operating angle changing mechanism includes a drive shaft that rotates in conjunction with a crankshaft, and an intake valve that is swingably fitted around the outer periphery of the drive shaft. A drive cam that is provided eccentrically to the drive shaft and that rotates integrally with the drive shaft, and that is rotatably mounted on the outer periphery of the drive cam. A first link to be fitted, a control shaft extending in the cylinder row direction substantially parallel to the drive shaft, a control cam provided eccentrically to the control shaft, and integrally rotating with the control shaft; A rocker arm which is fitted to the outer periphery of the cam so as to be relatively rotatable and has one end rotatably connected to the first link; and a second rocker arm rotatably connected to the other end of the rocker arm and the tip of the swing cam. Link, intake valve operating angle and As changing the Ruburifuto amount,
And an actuator for changing the operating angle for rotating the control shaft.

Preferably, the phase change mechanism is configured as follows.
As in the invention according to the second aspect, an outer cylinder portion that rotates in synchronization with the crankshaft, and an inner cylinder that is arranged coaxially with the outer cylinder portion and rotates integrally with a drive shaft that opens and closes an intake valve. A cylinder, an annular plunger interposed between the outer cylinder and the inner cylinder, and an inner plunger for changing the relative rotational phase of the inner cylinder and the outer cylinder.
A phase changing actuator driven in the axial direction of the outer cylinder.

[0027]

According to the present invention, when knocking is avoided, the ignition timing, the operating angle, and the center phase are maintained or variably controlled based on the actual operating angle and the actual center phase. In addition to performing fine control in accordance with the actual opening / closing timing of the vehicle, it is possible to effectively and reliably avoid knocking, and to minimize a decrease in driving performance due to the avoidance of knocking.

More specifically, when knocking is detected, knocking can be immediately suppressed by rapidly retarding the ignition timing, and at the same time, the operating angle and the center phase can be maintained or varied. The ignition timing can be advanced appropriately by controlling and replacing the knocking avoidance by these operating angle characteristics, and a decrease in fuel efficiency due to the retardation of the ignition timing can be suppressed.

According to the eleventh aspect of the present invention, the connecting portions of the members such as the sliding contact portion between the drive cam and the first link and the sliding contact portion between the control cam and the rocker arm are in surface contact. As a result, lubrication can be easily performed, durability and reliability are excellent, and resistance at the time of switching is suppressed to be low. Further, since the swing cam and the like are arranged coaxially with the drive shaft, the control accuracy is superior to a configuration in which the swing cam is supported by another support shaft different from the drive shaft, for example. At the same time, the device itself becomes compact, and the vehicle mountability is good. Further, the operating angle of the intake valve can be maintained at an arbitrary operating angle within a predetermined range, and the degree of freedom of control is higher than that in, for example, switching control of the operating angle between two positions.

Further, the phase change mechanism according to the twelfth aspect of the present invention is compact and excellent in mountability on an engine, and the number of parts is suppressed to be low. In addition, even when used in combination with the operating angle changing mechanism according to claim 11, they can be arranged without interfering with each other. Further, the center phase of the operating angle of the intake valve can be maintained at an arbitrary phase within a predetermined range, and the degree of control freedom is higher than that of, for example, switching control to two positions.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which a knocking control device according to the present invention is applied to a gasoline internal combustion engine with a turbocharger will be described in detail with reference to the drawings.

FIGS. 1 to 4 show the mechanical structure of the operating angle changing mechanism 10 for changing the operating angle of the intake valve 1. One or more intake valves 1 are provided in each cylinder of the internal combustion engine, and a valve lifter 2 is arranged above each intake valve 1. Above these valve lifters 2, a drive shaft 3 that is driven to rotate around its axis in conjunction with a crankshaft (not shown) extends in the direction of the cylinder rows. A swing cam 4 is swingably fitted around the outer periphery of the drive shaft 3 corresponding to each intake valve 1. The swing cam 4 comes into contact with and presses the valve lifter 2. The intake valve 1 is driven to open and close against the spring force of a valve spring (not shown).

The operating angle changing mechanism 10 includes these drive shafts 3
By changing the attitude of a link provided between the swing cam 4 and the swinging cam 4 and mechanically linking the two with each other, FIGS.
In the range from the minimum operating angle (zero lift) shown in FIG. 2 to the maximum operating angle (full lift) shown in FIGS. 3 and 4, the operating angle of the intake valve 1 can be continuously changed and maintained at an arbitrary operating angle. I have. 1 and 3 show a state in which the swing cam 4 swings in the valve-opening direction (clockwise direction in the drawing), and FIGS. (In the counterclockwise direction of FIG. 2).

More specifically, the operating angle changing mechanism 10 is provided eccentrically on the drive shaft 3, and has a drive cam 11 that rotates integrally with the drive shaft 3, and an externally rotatable outer periphery of the drive cam 11. Ring-shaped link (first link) 12 to be fitted
And a control shaft 1 extending in the cylinder row direction substantially parallel to the drive shaft 3.
3, a control cam 14 provided eccentrically to the control shaft 13 and rotating integrally with the control shaft 13; a control cam 14 which is fitted around the outer periphery of the control cam 14 so as to be relatively rotatable; And a rocker arm 15 rotatably connected to the other end of the rocker arm 15 and the tip of the swing cam 4.
Link (second link) 1 for mechanically linking
And 6.

The drive shaft 3 and the control shaft 13 are rotatably supported on the cylinder head side of the internal combustion engine via a bearing bracket (not shown). One end of the control shaft 13 is provided with a hydraulic or electromagnetic actuation angle changing actuator 17 for driving the control shaft 13 to rotate around the axis within a predetermined control angle range and for maintaining the control shaft 13 at a predetermined rotation phase. The actuator 17 is controlled by a control unit (control unit) 40.

The control unit 40 is a digital computer system having a well-known CPU, memory, etc., and includes a water temperature sensor 41, a rotation speed sensor 42, and a hydraulic pressure sensor 4.
3. Detection signals from various sensors for detecting the operating state of the engine, such as a supercharging pressure sensor 46 and a knocking sensor 47, in addition to a throttle (or accelerator) opening sensor 44, a suction pressure (or suction air amount) sensor 45, and the like. Based on
As will be described later, the fuel injection timing and the injection amount are variably controlled, the ignition timing is variably controlled (ignition timing changing means), and a control signal is sent to the operating angle changing actuator 17 and the phase changing actuator 38. Output,
The operating angle of the intake valve 1 and its central phase are maintained or variably controlled.

With such a configuration, when the drive shaft 3 rotates in conjunction with the crankshaft, the ring-shaped link 12 substantially moves in translation via the drive cam 11 and the rocker arm 15 moves around the control cam 14. Rocks,
The swing cam 4 swings via the rod-like link 16, and the intake valve 1 is driven to open and close.

Further, by controlling the rotation of the control shaft 13, the control cam 14 serving as the rocking center of the rocker arm 15 is controlled.
, The posture of each link 12, 16 and the like changes, the swing angle range of the swing cam 4 changes, and the valve lift characteristics change. Specifically, as shown in FIG. 5, the operating angle and the valve lift continuously change while the center phase of the operating angle remains substantially constant.

The operating angle changing mechanism 10 having such a mechanical structure connects various members such as a sliding contact portion between the driving cam 11 and the ring-shaped link 12 and a sliding contact portion between the control cam 14 and the rocker arm 15. Because the parts are in surface contact, lubrication is easy and durability and reliability are excellent.
Resistance at the time of switching is also suppressed low. In addition, since the swing cam 4 and the like are arranged coaxially with the drive shaft 3, the control accuracy is excellent compared to a configuration in which the swing cam is supported by another support shaft different from the drive shaft. In addition, the device itself becomes compact, and the vehicle mountability is good. Further, since the operating angle of the intake valve 1 can be maintained at an arbitrary operating angle within a predetermined range, the degree of freedom of control is higher than, for example, switching control of the operating angle to two positions.

FIG. 6 shows the mechanical structure of the phase changing mechanism 20 for changing the center phase of the operating angle of the intake valve 1.
The drive shaft 3 is rotatably supported on the cylinder head side via a bearing bracket 5, and a cam pulley (or sprocket) 6 is coaxially arranged on the outer peripheral side of the drive shaft 3. Rotational power is transmitted from the crankshaft to the cam pulley 6 via a chain or a timing belt, and the cam pulley 6 rotates in synchronization with the crankshaft.

The phase changing mechanism 20 is provided in a rotational power transmission path between the cam pulley 6 and the drive shaft 3 and changes the rotational phase of the two 6 and 3 so that the operating angle of the intake valve 1 is changed. The center phase is continuously changed within a predetermined range without changing the magnitude of the center, and is maintained at an arbitrary phase.

More specifically, the phase changing mechanism 20 is integrally formed on the inner peripheral side of the cam pulley 6,
And an outer cylinder portion 21 integrally rotating with the drive shaft 3 and a bolt 2
2, an inner cylindrical portion 23 which is fastened and fixed via the drive shaft 3 and rotates integrally with the drive shaft 3, a ring-shaped plunger 24 interposed between the outer cylindrical portion 21 and the inner cylindrical portion 23, A return spring 25 that constantly urges the plunger 24 in one direction (leftward in the figure). A sleeve 26 is fixed to the inner peripheral side of the outer cylindrical portion 21, and the sleeve 26 is rotatably supported by the bearing bracket 5 via a bearing 27.

Here, the inner and outer peripheral surfaces of the plunger 24,
The meshing portion 28 with the outer peripheral surface of the inner cylindrical portion 23 and the inner peripheral surface of the outer cylindrical portion 21 is a helical spline. Accordingly, by moving the plunger 24 in the axial direction (the left-right direction in FIG. 6) of the inner and outer cylindrical portions 23 and 21 by a phase changing actuator 38 described later, the movement in the axial direction is made to move between the inner cylindrical portion 23 and the outside. The rotation is converted into a relative rotational motion with the cylindrical portion 21, and the relative rotational phase between the outer cylindrical portion 21 and the inner cylindrical portion 23 changes continuously. For example, in the state where the plunger 24 is arranged in the leftmost direction in FIG. 6 (the state in FIG. 6), the waveform (b) in FIG.
As shown by, the operating angle of the intake valve 1 is maintained at the most retarded phase. On the other hand, in a state where the plunger 24 is arranged on the rightmost side in FIG. 6, as shown by a waveform (a) in FIG.
The operation angle of the intake valve 1 is set to the most advanced phase.

The above-described phase changing actuator 38
In this example, the operating hydraulic pressure to the advance hydraulic chamber 31 and the retard hydraulic chamber 32 defined before and after the plunger 24 is switched and controlled to move and hold the plunger 24 at a predetermined axial position. It is configured as a hydraulic actuator. The advance-side hydraulic chamber 31 is defined in a liquid-tight manner between one end of the plunger 24 and an end cap 30 fixed to the outer cylindrical portion 21 via a pin 29. Oil passage 3 formed in drive shaft 3
Hydraulic control valve 35 via 3a, 33b, 33c, 33d
It is connected to the. The retard side hydraulic chamber 32 is provided with the plunger 2.
4 is liquid-tightly defined on the other end side, and is connected to a hydraulic control valve 35 via an oil passage 34. This hydraulic control valve 3
An oil pump 37 that supplies hydraulic oil from an oil pan 36 is connected to 5, and the hydraulic pressure supplied to the hydraulic chambers 31 and 32 is switched based on a control signal from the control unit 40.

Such a phase changing mechanism 20 is compact and excellent in mountability on an engine, and the number of parts is suppressed to be low. Further, even when used in combination with the above-described operation angle changing mechanism 10, they can be arranged without interfering with each other. Furthermore, the center phase of the operating angle of the intake valve 1 can be maintained at an arbitrary phase within a predetermined range, and the degree of freedom of control is higher than, for example, switching control to two positions.

FIG. 8 schematically shows the structure of the turbocharger 50. The exhaust gas discharged from the cylinder 7 is supplied to an exhaust turbine 51 through an exhaust port 8a opened and closed by an exhaust valve 8. When the exhaust turbine 51 is rotated by this exhaust, an intake pipe 53 is provided by a compressor 52 provided back to back with the exhaust turbine 51.
And the intake air supplied to the intake port 1a is pressurized.

Here, the exhaust system is provided with a bypass passage 53 that bypasses the exhaust turbine 51 so that the pressure in the intake pipe 53 does not exceed a set value. An exhaust bypass valve (waist gate valve) 54 is provided in the bypass passage 53.
Is controlled by the control unit 40 based on a detection signal of a supercharging pressure sensor 46 provided in the intake pipe 53 and the like.

A knocking sensor 47 (knocking detecting means) for detecting knocking vibration of a predetermined frequency is mounted on the cylinder block 9, and the knocking detection signal is input to the control unit 40. . Note that, for example, an in-cylinder pressure sensor may be provided in the washer portion of the ignition plug, and knocking may be detected based on a change in the in-cylinder pressure.

9 and 10 correspond to typical operating conditions (operating range) of the engine, and FIG. 10 schematically shows an example of a suitable opening / closing timing of the intake valve 1 according to each operating condition. Is shown.

When the engine is in an idle range (idling state), preferably, the operating angle is set to a minimum operating angle, and the opening timing (IVO) of the intake valve 1 is set to about 40 degrees after the top dead center in crank angle. And the closing time (IVC)
Is set to the retard side so that is just before the bottom dead center. That is, when the actual compression ratio is lowered in the idling range, the combustion stability deteriorates.
By delaying VO, residual gas and pump loss are reduced.

When the engine is in a constant speed (R / L) range,
Preferably, the operating angle is set to be substantially the same as the above-mentioned minimum operating angle so that the IVO is near the top dead center and the IVC is advanced from the bottom dead center, and the center phase is set to be more advanced than the idle range. Set to. That is, the actual stroke and the compression ratio are reduced, and the pump loss is greatly reduced.

When the engine is in a gradual acceleration range (partial load range) where the engine accelerates gently, the internal recirculation effect due to the expansion of the valve overlap and the advance of the IVC are set with the IVO before (or near) the top dead center. In order to obtain a synergistic effect with the pump loss reduction effect due to the actual stroke reduction, preferably, the operating angle is slightly enlarged (or substantially equal) to the R / L region, and the center phase is advanced to the idle region. Corner side (R
/ L range).

When the engine is in a low speed, high load (acceleration) range, in order to secure the maximum amount of intake air, the operating angle is preferably set so that IVC is near bottom dead center and IVO is near top dead center. Is further expanded from the partial load range, and the center phase is set on the retard side (similar to the idle range) than the R / L range and the partial load range.

When the engine is in the high-speed high-load region, it is most efficient to delay the IVC to lower the actual compression ratio and use it as a supercharging mirror cycle, as in the case where the supercharging pressure is increasing. Preferably, the central phase is set further on the retard side while the operating angle is further enlarged than in the above-mentioned rapid acceleration region.

As described above, since IVO and IVC (operating angle and center phase) are set so as to differ greatly according to each of the operating conditions, when knocking occurs, it is necessary to cope with the situation of IVO, IVC, etc. at that time. It is desirable to change the control logic by doing so. Hereinafter, a specific example of control corresponding to each of the operation conditions 1 to will be described with reference to the timing charts of FIGS.

11 to 14, (a) shows an output signal of the knocking sensor 47. While the knocking signal is at a relatively small level, the ignition timing (b) is set at a so-called trace knock level (optimum level). (Ignition timing). In other words, by advancing as far as possible within a range in which knocking does not occur, a state in which extremely weak knocking occurs is maintained.

On the other hand, when the frequency at which the knocking signal exceeds the slice level exceeds a predetermined value, the retardation of the ignition timing (b) and the control of the operating angle (c) and the center phase (d) of the intake valve are combined. It is determined that knocking avoidance control should be started (the timing of T1 in the figure corresponds to this).

For example, as shown in FIG. 11, when the engine is in an extremely low load region below a predetermined load including an idle region or in a constant speed (R / L) region, the IVC (f) is advanced more than the bottom dead center. When knocking is detected in the first operating state, the ignition timing is first quickly retarded by a predetermined retard amount ΔR1. In addition, since this retarding can be performed with good responsiveness, knocking is quickly suppressed.

At the same time, in order to avoid the deterioration of fuel efficiency due to the retardation of the ignition timing, the operating angle and the center phase of the intake valve are maintained or variably controlled to prevent knocking due to the operating angle characteristic. I will replace it. Since the control of the operating angle and the center phase involves a mechanical delay,
The actual operating angle gradually changes depending on the operating speed of each of the actuators 17 and 38, as shown in FIGS.

Specifically, IVO (e) is kept substantially constant from the retard start timing T1 of the ignition timing to the timing T2 when the operating angle and the center phase of the intake valve reach the target value (T1 → T2). Meanwhile, the operating angle is slightly reduced and the center phase is advanced so that IVC (f) is advanced to lower the actual compression ratio. This reduces the actual compression ratio,
Knocking is unlikely to occur. Under normal temperature conditions, an excessive decrease in the actual compression ratio causes deterioration of combustion,
Under high temperature conditions where knocking occurs, there is enough room to lower the actual compression ratio. Thus, IVC (f)
Is gradually advanced (T1 → T2), there is no problem if the ignition timing (b) is gradually returned to the advanced side accordingly.

Then, the operating angle and the center phase (IVO, I
After it is detected that VC) has reached the target value (T2), the above-described trace knock control of the ignition timing is restarted, the trace knock level is searched, and the trace knock level is fixed (similarly in FIGS. 12 to 14).

On the other hand, as shown in FIG. 12, the engine is in the moderate acceleration range, the opening timing (e) of the intake valve is advanced more than the top dead center, and the closing timing (f) of the intake valve is increased. In the second operating state where the angle is advanced more than the bottom dead center, the pump loss is set to a maximum reduction, so that the suction negative pressure is low and the throttle valve is almost fully open.

When knocking occurs in the second operating state,
If the actual compression ratio is reduced by advancing the IVC, the charging efficiency is reduced, and the acceleration capacity tends to be insufficient. In this case, the setting approaches a low-speed and high-load region as in the case where the accelerator is depressed, so that the IVC is forced to have a large retardation. Therefore, such a second
When the knock is detected in the operation state (T1), since securing of the torque is the highest priority, the IVC is retarded so as to increase the actual compression ratio to secure the intake air amount, and the ignition timing is significantly increased. It is necessary to avoid knocking due to a large retardation.

That is, when knock occurrence is detected (T
1) First, in order to quickly suppress the occurrence of knocking,
The ignition timing is immediately retarded by a predetermined retard amount ΔR2. In the subsequent change period T1 → T2, while the operating angle is kept substantially constant, the center phase is gradually retarded to bring the closing timing closer to the bottom dead center, thereby improving the charging efficiency (ie, increasing the intake air amount). In addition, knocking is avoided by gradually changing the ignition timing further to the retard side in accordance with the retardation of the center phase. At this time, since the valve overlap is reduced with the retardation of the opening timing of the intake valve, high-temperature residual gas is reduced, which is effective in avoiding knock. However, the operating angle may be gradually increased in accordance with the retardation of the center phase so as to keep the valve overlap amount substantially constant in order to maintain the fuel efficiency improving effect at all.

As shown in FIG. 13, in the third operating state where the engine is in the low-speed high-load region and the IVC is after the bottom dead center but near the bottom dead center (the retard amount is very small), The actual compression ratio is extremely high (substantially the highest value), and near the bottom dead center, the sensitivity of the reduction of the actual compression ratio due to the retardation of the IVC is extremely low. Therefore, also in this case, it is difficult to avoid knocking only by retarding the IVC, and the ignition timing is retarded to quickly and surely avoid knocking, and after the retarding amount of the IVC takes effect, It is necessary to devise control such as recovering the ignition timing.

Specifically, as in the above case, immediately after knocking detection (T1), the ignition timing is first retarded immediately by a predetermined retard amount ΔR3 to avoid knocking. At the same time, the operating angle is expanded and the central angle is retarded so that the IVC is retarded while maintaining the IVO substantially constant, so as to shift to avoid knocking due to a decrease in the actual compression ratio. To gradually return the ignition timing to the advance side.

As shown in FIG. 14, in the fourth operating state in which the engine is in a high-speed and high-load region and the IVC has already been retarded by a considerable amount, the charging efficiency is near the maximum value, but the IVC is retarded. Therefore, it is effective to minimize the retardation of the ignition timing with a high exhaust temperature rise and to avoid knocking mainly by retarding the IVC.

Specifically, immediately after knocking is detected, T
The retard amount ΔR4 of the first ignition timing is set to a minimum (it does not need to be performed), that is, set sufficiently smaller than the above-mentioned ΔR1 to ΔR3. Then, while keeping the IVO substantially constant, the operating angle is increased and the center phase is retarded so that the actual compression ratio is reduced by retarding the IVC.

FIG. 15 is a flowchart executed by the control unit 40, and shows the overall flow of the above-described knock avoidance control.

First, step (simply indicated as S in the figure) 1
At 1, it is determined whether knocking has occurred.
More specifically, based on an output signal from knocking sensor 47, it is determined whether the frequency of occurrence of knocking at or above the slice level exceeds a predetermined value. If it is equal to or smaller than the predetermined value, the knocking avoidance control routine ends.

In the following step 12, the current IVO, I
The control status of the VC is indirectly detected. Specifically, the current IVO and IVC are calculated based on the current actual operating angle and the actual center phase of the intake valve 1. The actual operating angle is estimated from the current target operating angle or directly detected by an operating angle sensor (not shown) that detects the rotational phase of the control shaft 13 (operating angle obtaining means). The actual center phase is estimated from the current target phase, or directly detected by a phase detection sensor (not shown) for detecting the rotation phase of the drive shaft 3 and the rotation speed sensor 42 (phase acquisition means).

In steps 13 and 14, these IVs
O, IVC, the ignition timing IA (ignition advan
ce), and the IA retard control is executed based on the retard amount (step 14).

In step 15, the sensitivity of adjusting the actual compression ratio of IVC and the sensitivity of adjusting residual gas of IVO are calculated. In addition,
The actual compression ratio adjustment sensitivity of the IVC is divided into several stages based on, for example, a predetermined control logic. As this control logic, the actual compression ratio is determined by “whether the IVC is before or after bottom dead center”. In addition to a simple control logic based on a rough difference in sensitivity such that the lowering direction is reversed, detailed and highly accurate while taking into account the difference in stroke displacement sensitivity due to the crank angle of the IVC and the IVC that maximizes the charging efficiency. Advanced control logic utilizing a database (step 16) can be used.

The sensitivity of the IVO to adjust the residual gas is related to the possibility of knocking due to the ratio of the residual gas at a high temperature.
These are also taken into account in the setting of VC and IVO (steps 17 and 18). For example, IVC, IV
In the O setting, if the IVC is advanced, the pump loss is reduced, while the actual compression ratio is also reduced. Since the advance angle of the IVC is limited,
Instead, the IVO is advanced so as to increase the residual gas ratio, so that the intake air temperature increases and the decrease in the compression end temperature due to the decrease in the actual compression ratio can be compensated. On the other hand, in the R / L region, if the amount of residual gas is large, the combustion deteriorates quickly, so that such a setting cannot be used. As described above, the setting of the IVC and IVO in the step 17 is based on a complicated effect diagram, and the setting of the IVO and the IV
In addition to the controllable range of C, it is necessary to store the sensitivity corresponding to the operating conditions as a database.

A target operating angle and a target center phase are set based on the settings of IVO and IVC set in this way (step 19). Based on the target operating angle and the target center phase, each of the actuators 17, 38 is driven (step 20). At the same time, the ignition timing is appropriately controlled to be advanced or retarded in accordance with changes in the operating angle and the center phase. Then, in step 21, IVO, IVC
Is determined to have reached the target value, trace knock control of the ignition timing is restarted, and the process returns to step 11 described above.

As described above, according to the present embodiment, when knocking is avoided, the ignition timing, the operating angle, and the center phase are maintained or variably controlled based on the actual operating angle and the actual center phase. In addition, fine control according to the actual opening / closing timing of the intake valve can be performed, and knocking can be effectively and reliably avoided, and a decrease in driving performance due to the avoidance of knocking can be suppressed to a minimum.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a mechanical configuration of an operating angle changing mechanism according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a mechanical configuration of an operating angle changing mechanism.

FIG. 3 is a configuration diagram showing a mechanical configuration of an operating angle changing mechanism.

FIG. 4 is a configuration diagram showing a mechanical configuration of the operating angle changing mechanism.

FIG. 5 is a characteristic diagram showing how the operating angle of the intake valve is changed by the operating angle changing mechanism of the embodiment.

FIG. 6 is a configuration diagram showing a mechanical configuration of a phase change mechanism of the embodiment.

FIG. 7 is a characteristic diagram showing how the center phase of the operating angle is changed by the phase changing mechanism of the embodiment.

FIG. 8 is a configuration diagram showing an internal combustion engine with a supercharger according to the embodiment.

FIG. 9 is a characteristic diagram showing a rotation speed-torque characteristic of the internal combustion engine.

FIG. 10 is a characteristic diagram schematically showing a suitable opening / closing timing of an intake valve corresponding to each operating condition of the engine.

FIG. 11 is a timing chart showing characteristics when knocking is detected in the first operating state.

FIG. 12 is a timing chart showing characteristics when knocking is detected in a second operating state.

FIG. 13 is a timing chart showing characteristics when knocking is detected in a third operating state.

FIG. 14 is a timing chart showing characteristics when knocking is detected in a fourth operation state.

FIG. 15 is a flowchart illustrating an example of a control flow according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intake valve 10 ... Operating angle changing mechanism 11 ... Drive cam 12 ... Ring-shaped link 13 ... Control shaft 14 ... Control cam 15 ... Rocker arm 16 ... Rod-shaped link 17 ... Actuating angle changing actuator 20 ... Phase changing mechanism 21 ... Outer cylinder part 23 ... Inner cylinder part 24 ... Plunger 38 ... Phase change actuator 40 ... Control unit 47 ... Knocking sensor (knock detection means) 50 ... Turbocharger

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01L 13/00 301 F01L 13/00 301A 3G301 301K F02D 13/02 F02D 13/02 D 41/22 301 41 / 22 301B 320 320 43/00 301 43/00 301B 301Z F02P 5/152 F02P 5/15 D 5/153 17/00 R 17/12 F term (reference) 3G018 AB07 AB16 BA01 BA17 BA32 BA34 CA06 CA20 DA04 DA08 DA19 DA57 DA66 DA70 DA74 DA76 DA77 DA83 EA08 EA12 EA13 EA14 EA22 EA31 EA32 EA33 EA35 FA01 FA06 FA07 FA08 FA09 FA26 FA27 GA00 GA07 3G019 AB01 AB05 DA02 DC06 GA14 GA15 3G022 BA01 CA03 CA06 CA09 DA02 DA04 DA05 EA08 BA09 DA38 EB08 FA00 FA11 FA25 3G092 AA11 AA18 BA09 DA01 DA05 DA06 DB03 EA03 EA04 EC10 FA16 GA04 GA05 GA06 GA0 8 GA12 GA17 GA18 HA12Z HA13Z HA16Z HC05Z 3G301 HA01 HA11 HA19 JA22 KA07 KA08 KA09 KA12 KA21 KA24 KA25 LA00 LA07 NC04 NE11 NE12 PA00Z PA16Z PC08Z PE10Z

Claims (12)

[Claims] An operating angle changing mechanism for changing an operating angle of an intake valve; a phase changing mechanism for changing a center phase of the operating angle of the intake valve; an ignition timing changing means for changing an ignition timing; Knocking detecting means for detecting occurrence of knocking, operating angle obtaining means for detecting or estimating the actual operating angle of the intake valve, and phase obtaining means for detecting or estimating the actual center phase of the intake valve, A knocking control device for an internal combustion engine, wherein when knocking is detected, the ignition timing, the operating angle, and the center phase are maintained or variably controlled based on the actual operating angle and the actual center phase at this time. 2. In a first operating state in which the engine is in an extremely low load range or a constant speed range below a predetermined load including an idle range, and at least the closing timing of the intake valve is advanced from the bottom dead center, 2. The knocking control device for an internal combustion engine according to claim 1, wherein when knocking is detected, the ignition timing is quickly retarded and the center phase is advanced. 3. The method according to claim 1, wherein when knocking is detected in the first operating state, the operating angle is reduced in accordance with the advance of the center phase so as to keep the opening timing of the intake valve substantially constant. Item 3. A knocking control device for an internal combustion engine according to Item 2. 4. A second operation in which the engine is in a moderate acceleration range, the opening timing of the intake valve is advanced from TDC, and the closing timing of the intake valve is advanced from BDC. The engine according to any one of claims 1 to 3, wherein when knocking is detected in the state, the central phase of the intake valve is retarded, and the ignition timing is gradually retarded in accordance with the retardation of the central phase. Knocking control device for an internal combustion engine according to claim 1. 5. The system according to claim 1, wherein when knocking is detected in the second operating state, the operating angle is increased in accordance with the retardation of the center phase so as to keep the valve overlap substantially constant. A knocking control device for an internal combustion engine according to claim 4. 6. The ignition timing is promptly retarded when knocking is detected in a third operating state in which the engine is in a low-speed high-load region and at least the closing timing of the intake valve is located near bottom dead center. The knocking control device for an internal combustion engine according to any one of claims 1 to 5, wherein the central phase is retarded. 7. When the knocking is detected in the third operating state, the operating angle is increased in accordance with the retardation of the center phase so as to keep the opening timing of the intake valve substantially constant. A knocking control device for an internal combustion engine according to claim 6. 8. When the engine is in a high speed range and knocking is detected in at least a fourth operating state in which the closing timing of the intake valve is retarded from bottom dead center, the center phase of the intake valve is retarded. The knocking control device for an internal combustion engine according to any one of claims 1 to 7, wherein the knocking control device is configured to: 9. When the knocking is detected in the fourth operating state, the operating angle is expanded in accordance with the retardation of the center phase so as to keep the opening timing of the intake valve substantially constant. The knocking control device for an internal combustion engine according to claim 8. 10. The knocking control device for an internal combustion engine according to claim 8, wherein, when knocking is detected in the fourth operation state, the ignition timing is promptly retarded. 11. The operating angle changing mechanism is provided between a drive shaft that rotates in conjunction with a crankshaft and a swing cam that swingably fits around the outer periphery of the drive shaft and drives an intake valve. A drive cam that is provided eccentrically to the drive shaft and rotates integrally with the drive shaft, a first link externally fitted to the outer periphery of the drive cam so as to be relatively rotatable, A control shaft extending substantially parallel to the shaft in the cylinder row direction; a control cam provided eccentrically to the control shaft and rotating integrally with the control shaft; and a control shaft externally rotatable relative to the outer periphery of the control cam. A rocker arm having one end rotatably connected to the first link; a second link rotatably connected to the other end of the rocker arm and a tip of the swing cam; To change the valve lift Knock control apparatus for an internal combustion engine according to claim 1, characterized in that it has a an actuator for operating angle changes for rotating the control shaft. 12. The phase change mechanism includes an outer cylinder portion that rotates in synchronization with the crankshaft, a coaxial arrangement with the outer cylinder portion, and a drive shaft that opens and closes an intake valve. An inner cylinder that rotates, an annular plunger interposed between the outer cylinder and the inner cylinder, and the plunger that changes the relative rotational phase of the inner cylinder and the outer cylinder. The intake valve drive control device for an internal combustion engine according to any one of claims 1 to 11, further comprising: a phase changing actuator that drives the inner cylinder and the outer cylinder in the axial direction.