JP3669175B2 - Preignition prevention device for variable valve engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for preventing preignition (premature ignition) by controlling the variable valve means in an engine having variable valve means for variably controlling the lift characteristics of intake and exhaust valves.
[0002]
[Prior art]
As a technology to prevent preignition, which is irregular combustion of the engine, conventionally, when preignition is detected, the throttle valve is moved in the closing direction to reduce the total gas amount in the cylinder, and the in-cylinder gas temperature during the compression stroke There is a known method for reducing the above (Japanese Patent Laid-Open No. 8-319931).
[0003]
[Problems to be solved by the invention]
However, in such a conventional pre-ignition prevention method, when the throttle valve is closed to generate intake negative pressure in order to reduce the intake air amount, on the other hand, during the overlap period of the intake and exhaust valves, the exhaust passage enters the cylinder. As a result, the amount of high-temperature burned gas entering increases, the temperature of the in-cylinder mixture during the compression stroke increases, the oxidation reaction rate of hydrocarbons increases, and the occurrence of preignition is promoted.
[0004]
Therefore, it is necessary to increase the throttle valve closing amount to reduce the total gas amount so that the gas reaction temperature during the compression stroke becomes equal to or lower than the oxidation reaction rate before ignition. There was a tendency to grow.
The present invention has been made by paying attention to such a conventional problem, and it is possible to effectively prevent pre-ignition while suppressing a torque reduction margin by controlling the variable valve. An object of the present invention is to provide an ignition prevention device.
[0005]
[Means for Solving the Problems]
  For this reason,The present invention is shown in FIG.As shown in FIG. 1, in an engine having variable valve operating means for variably controlling the lift characteristics of the intake / exhaust valves, pre-ignition detection means for detecting pre-ignition and pre-ignition are detected.Sometimes the exhaust valve closing timing control means for controlling the variable valve operating means so that the closing timing of the exhaust valve is close to top dead center;
  It is characterized by comprising
[0008]
  The present inventionAccording to the above, when the pre-ignition is detected by the pre-ignition detecting means, the variable valve operating means is controlled by the exhaust valve closing timing control means so that the closing timing of the exhaust valve is close to the top dead center.
  As a result, the exhaust valve is closed when the amount of burnt gas remaining in the cylinder near the exhaust top dead center is the smallest, and the proportion of high-temperature burned gas in the compressed mixture decreases. Pre-ignition can be avoided by reducing the in-cylinder gas temperature near the point.Also, the amount of fresh air is almost
Since it does not change, it is not necessary to reduce the torque.
[0011]
  Also,As shown in FIG. 4, it further comprises open overlap amount control means for controlling the variable valve means so as to reduce the open overlap amount of the intake / exhaust valves when pre-ignition is detected. Also good.
[0012]
  According to such invention,When pre-ignition is detected by the pre-ignition detection means, the variable valve means is controlled by the open overlap amount control means so as to reduce the open overlap amount of the intake / exhaust valve, and the exhaust valve closing timing control The variable valve operating means is controlled by the means so that the closing timing of the exhaust valve approaches the top dead center.
[0013]
This reduces the amount of burnt gas that blows back into the cylinder from the exhaust passage, and closes the exhaust valve when the amount of burnt gas remaining in the cylinder near the exhaust top dead center is minimized. In addition, the proportion of the high-temperature burned gas is reduced, so that the in-cylinder gas temperature near the compression top dead center is reduced and pre-ignition can be avoided.
Further, since the amount of fresh air is hardly changed, it is not necessary to reduce the torque.
[0014]
  Also,In the above invention,When pre-ignition is detected, the variable valve means is first controlled so as to reduce the open overlap amount of the intake / exhaust valve by the open overlap amount control means, and then the exhaust valve closing timing control means controls the exhaust valve. Control the variable valve mechanism so that the closing timing approaches the timing at which the residual burned gas near top dead center is minimizedIt is good also as composition to do.
[0015]
  Such inventionAccording to the above, when pre-ignition is detected, the amount of burned gas blows back by first controlling the variable valve means so as to reduce the open overlap amount of the intake / exhaust valve by the open overlap amount control means. To prevent preignition, and if that is still not enough, the exhaust valve closing timing control means controls the variable valve means so that the closing timing of the exhaust valve is close to top dead center. Pre-ignition is more reliably avoided by adding an action to reduce the amount to a minimum.
[0020]
  Also,As shown in FIG. 6, the pre-ignition isWhen detected, the variable valve means is controlled so as to move the closing timing of the intake valve in a direction in which the intake air amount decreases.An intake valve closing timing control means may be further included.
[0021]
  Such inventionAccording to the above, when the pre-ignition is detected by the pre-ignition detection means, the variable valve means is controlled by the exhaust valve closing timing control means so that the closing timing of the exhaust valve is close to the top dead center, and the intake valve The variable valve operating means is controlled so that the closing timing moves in a direction in which the intake air amount decreases.
[0022]
  As a result, the exhaust valve is closed when the amount of burned gas remaining in the cylinder near the exhaust top dead center is minimized, and the total gas amount in the cylinder is reduced. The temperature decreases and preignition can be avoided.
  Also,In the above invention,When pre-ignition is detected, the variable valve means is first controlled by the exhaust valve closing timing control means so that the closing timing of the exhaust valve approaches the timing at which the residual burned gas near the top dead center is minimized, and then The variable valve mechanism is controlled by the intake valve closing timing control means so that the closing timing of the intake valve moves in the direction in which the intake air amount decreases.It is good also as composition to do.
[0023]
  According to such invention,When pre-ignition is detected, the variable valve mechanism is first controlled by the exhaust valve closing timing control means so that the closing timing of the exhaust valve approaches the timing at which the residual burned gas near top dead center is minimized. If the residual burned gas amount is reduced to avoid pre-ignition, and if this is not enough, the intake valve closing timing control means moves the intake valve closing timing so that the intake air amount decreases. By controlling the means, the action of reducing the total gas amount in the cylinder is added, and preignition is more reliably avoided.
[0024]
  Also,As shown in FIG.Pre-ignition detection means for detecting pre-ignition in an engine equipped with variable valve means for variably controlling the lift characteristics of the intake / exhaust valves, and opening and closing of intake / exhaust valves when pre-ignition is detected Open overlap amount control means for controlling the variable valve means to reduce the amount, and control the variable valve means so that when the pre-ignition is detected, the closing timing of the exhaust valve approaches the top dead center An exhaust valve closing timing control means; an intake valve closing timing control means for controlling the variable valve operating means so as to move the closing timing of the intake valve in a direction in which the intake air amount decreases when pre-ignition is detected; IncludingIt may be configured.
[0025]
  According to such invention,When pre-ignition is detected by the pre-ignition detection means, the variable valve means is controlled by the open overlap amount control means so as to reduce the open overlap amount of the intake / exhaust valve, and by the exhaust valve closing timing control means. The variable valve means is controlled so that the closing timing of the exhaust valve approaches the top dead center, and the variable valve means is controlled so that the closing timing of the intake valve moves in a direction in which the intake air amount decreases.
[0026]
  This reduces the amount of burnt gas that blows back into the cylinder from the exhaust passage, closes the exhaust valve when the amount of burnt gas remaining in the cylinder near the exhaust top dead center is minimized, and reduces the total gas in the cylinder. Since the amount is reduced, the in-cylinder gas temperature near the compression top dead center is reduced, and pre-ignition can be avoided.
  Also,In the above invention,When pre-ignition is detected, the variable valve means is first controlled so as to reduce the open overlap amount of the intake / exhaust valve by the open overlap amount control means, and then the exhaust valve closing timing control means controls the exhaust valve. The variable valve means is controlled so that the closing timing approaches the top dead center. Finally, the variable valve means is moved by the intake valve closing timing control means so that the intake valve closing timing is moved in the direction in which the intake air amount decreases. ControlIt is good also as a structure.
[0027]
  According to such invention,When pre-ignition is detected, the amount of burnt gas is reduced by controlling the variable valve means so that the open overlap amount of the intake and exhaust valves is first reduced by the open overlap amount control means. If pre-ignition is avoided, and if that is not enough, the residual valve gas control system controls the variable valve mechanism so that the exhaust valve closing timing approaches the top dead center. If this is not sufficient, the variable valve means is controlled by the intake valve closing timing control means so that the intake valve closing timing is moved in the direction in which the intake air amount decreases. Thus, the action of reducing the total gas amount in the cylinder is added and the pre-ignition is more reliably avoided.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In FIG. 8 showing the overall configuration of one embodiment, an intake valve 3 and an exhaust valve 4 whose opening and closing are electronically controlled by a valve drive device 2 are mounted on the engine 1. A fuel injection valve 6 is attached to the intake port 5 of each cylinder, a spark plug 8 and an ignition coil 9 are attached to the combustion chamber 7, and pre-ignition detection means for detecting the in-cylinder pressure for pre-ignition detection. As shown in FIG. The pre-ignition detection means includes a method for detecting that the secondary voltage output of the spark plug 8 changes due to the combustion chemical reaction of the gas in the cylinder when pre-ignition occurs, vibration and pressure when pre-ignition occurs. A method of detecting the state with a knock sensor, a method of detecting in-cylinder ions generated by the combustion chemical reaction, a method of detecting the in-cylinder temperature, and the like can be used. The engine body is also provided with a crank angle sensor 11 that outputs a reference signal at the reference crank angle of each cylinder and outputs a unit angle signal for each minute crank angle.
[0029]
Signals from the in-cylinder pressure sensor 10, the crank angle sensor 11, and the like are output to the control unit 12, and the control unit 12 outputs a fuel injection signal to the fuel injection valve 6 based on these detection signals to control fuel injection. The ignition control is performed by outputting an ignition signal to the ignition coil 9, and the valve driving signal is output to the valve driving device 2 to control the opening and closing of the intake valve 3 and the exhaust valve 4. In particular, as a configuration according to the present invention, when pre-ignition is detected based on a signal from the in-cylinder pressure sensor 10, control for avoiding pre-ignition is performed by controlling the opening / closing timing of the intake and exhaust valves.
[0030]
The configuration of the valve drive device 2 is shown in FIG. In FIG. 9, the valve drive device 2 is provided integrally with a housing 21 made of a nonmagnetic material provided on the cylinder head and a stem of the intake valve 3 (or the exhaust valve 4, hereinafter referred to as the intake valve 3). Fixed in the housing 21 at a position facing the upper surface of the armature 22 so as to be able to exert an electromagnetic force for sucking the armature 22 and closing the intake valve 3 by sucking the armature 22 The valve closing electromagnet 23 and the armature 22 are fixedly disposed in the housing 21 at a position facing the lower surface of the armature 22 so as to exert an electromagnetic force for attracting the armature 22 and opening the intake valve 3. A valve opening electromagnet 24, a valve closing side return spring 25 for biasing the armature 22 in the valve closing direction of the intake valve 3, and a valve opening side for biasing the armature 22 in the valve opening direction of the intake valve 3 A return spring 26, and Constructed. Then, when both the valve closing electromagnet 23 and the valve opening electromagnet 24 are demagnetized, the valve closing side return spring 25 and the valve closing side return spring 25 are arranged so that the intake valve 3 is at a substantially central position between the fully opened position and the valve closing position. When the spring force with the valve opening return spring 26 is set and only the valve closing electromagnet 23 is excited, the intake valve 3 is closed, and when only the valve opening electromagnet 24 is excited, the intake valve 3 is opened. It is driven to fully open. The valve driving device 2 constitutes intake valve driving means.
[0031]
The opening / closing timing for intake / exhaust of the intake valve 3 and the exhaust valve 4 by the valve drive device 2 is usually a target opening / closing timing set based on the operating state of the engine 1 as shown in FIG. In particular, the closing timing IVC before the intake bottom dead center of the intake valve 3 is variably controlled over a wide range based on the accelerator opening and the engine speed, or the required torque set based on these. The intake air amount is controlled. Further, when pre-ignition is detected, the opening / closing timing of the intake / exhaust valves is controlled so as to avoid pre-ignition.
[0032]
  In the following, embodiments of the intake / exhaust valve opening / closing timing control at the time of detecting the pre-ignition will be described with reference to the flowchart of FIG. Figure 10The open overlap amount control means shown in FIG. 1 is provided.The flowchart which concerns on 1st Embodiment is shown. This flow is executed at a predetermined time period (the same applies to the following flows).
  Step (denoted as S in the figure, the same applies hereinafter) In step 1, pre-ignition is measured. Specifically, based on the signal from the in-cylinder pressure sensor 10, the occurrence of pre-ignition is detected from the level of in-cylinder pressure fluctuation near the compression top dead center considering the ignition timing or the ignition delay period, and the pre-ignition is detected. The frequency of occurrence is measured, or the in-cylinder pressure fluctuation near the compression top dead center is integrated.
[0033]
In step 2, it is determined whether the pre-ignition has occurred at a level that should be avoided, depending on whether the pre-ignition occurrence frequency or the in-cylinder pressure fluctuation integrated value exceeds a certain value.
If it is determined in step 2 that pre-ignition has occurred at a level that should be avoided, control proceeds to step 3 and subsequent steps to control the intake / exhaust valve opening / closing timing to avoid pre-ignition.
[0034]
In step 3, the target open overlap amount of the intake / exhaust valve is calculated. Here, the target open overlap amount is set smaller than the normal open overlap amount so as to avoid pre-ignition.
In step 4, a target exhaust valve closing timing and a target intake valve opening timing are calculated so as to satisfy the target opening overlap amount.
[0035]
In step 5, the valve drive device 2 is controlled so that the exhaust valve 4 is closed and the intake valve 3 is opened at the target exhaust valve closing timing and the target intake valve opening timing calculated in step 4. In this way, when detecting pre-ignition, by reducing the open overlap amount of the intake / exhaust valve, the amount of burned gas blown back into the cylinder from the exhaust passage is reduced, so that the high temperature burned gas in the compressed mixture Therefore, the pre-ignition can be avoided (see FIG. 13) by reducing the in-cylinder gas temperature near the compression top dead center (see FIG. 12).
[0036]
Further, even if the open overlap amount of the intake / exhaust valve is reduced, the amount of fresh air is not reduced, and the reduction of torque can be prevented. In addition, since the amount of fresh air slightly increases due to the decrease in the amount of residual burnt gas, the closing timing of the intake valve 3 is advanced (in the case of the early closing mirror cycle in which the intake valve is closed in the intake stroke) or delayed ( In the case of a delayed closing mirror cycle in which the intake valve is closed in the compression stroke), a configuration in which the amount of fresh air is not increased may be used, and an increase in torque can be suppressed.
[0037]
  Figure 14According to the basic embodiment (second embodiment) including the exhaust valve closing timing control means according to the present invention shown in FIG.A flowchart is shown.
  In Step 1 and Step 2, pre-ignition measurement and determination as to whether or not pre-ignition exceeding a predetermined level to be avoided is generated as described above. Then, when it is determined that pre-ignition exceeding a predetermined level has occurred, the routine proceeds to step 11 where the target closing timing of the exhaust valve 4 is set near the compression top dead center.
[0038]
In step 12, the valve drive device 2 is controlled so that the exhaust valve 4 is closed at the target closing timing.
In this way, when pre-ignition is detected, the exhaust valve closes at a time when the amount of burned gas remaining in the cylinder near the exhaust top dead center is minimized, so that high-temperature burned gas in the compressed mixture is obtained. Therefore, the pre-ignition can be avoided (see FIG. 13) by reducing the in-cylinder gas temperature near the compression top dead center (see FIG. 12).
[0039]
  In the second embodiment as well, an increase in torque can be suppressed by adjusting the opening timing of the intake valve 3 in order to suppress an increase in the amount of fresh air due to a decrease in residual burned gas.
  Figure 16The intake valve closing timing control means shown in FIG. 3 is provided.9 shows a flowchart according to a third embodiment.
  In Step 1 and Step 2, pre-ignition measurement and generation level determination are performed as described above.
[0040]
If it is determined that pre-ignition is occurring at a predetermined level or higher, the routine proceeds to step 21, where the target closing timing of the intake valve is changed and set so as to decrease the intake air amount. That is, in the case of the early closing mirror cycle, the closing timing is advanced, and in the case of the late closing mirror cycle, the closing timing is delayed.
In step 22, the valve drive device 2 is controlled so that the intake valve 3 is closed at the target closing timing.
[0041]
In this way, when pre-ignition is detected, the intake valve closes so that the amount of intake air (fresh air) decreases (see FIG. 17). The in-cylinder gas temperature near the point decreases (see FIG. 18), and pre-ignition can be avoided (see FIG. 13).
19 to 22 show the fourth to seventh embodiments, which are combined with the preignition avoidance control of the first to third embodiments.
[0042]
That is, in the fourth embodiment shown in FIG. 19, when the pre-ignition level of a predetermined level or higher is detected in steps 1 to 5 in the same manner as in the first embodiment, the intake / exhaust valve opening overlaps. After performing the control to reduce the amount, it is determined again in step 31 whether or not pre-ignition is generated at a predetermined level or more. If it is determined that it has elapsed, the valve drive device 2 is controlled in steps 33 and 34 so that the exhaust valve 4 is closed near the compression top dead center in the same manner as in the second embodiment. To do.
[0043]
In this way, when pre-ignition is detected, by first reducing the open overlap amount of the intake and exhaust valves, the amount of burnt gas blown back is reduced to avoid pre-ignition, which is still not sufficient In this case, pre-ignition can be avoided more reliably by reducing the amount of residual burned gas so that the closing timing of the exhaust valve approaches the top dead center.
[0044]
  Also,Figure 20 FIG. 5 shows a flowchart according to a fifth embodiment provided with the opening overlap amount control means and the intake valve closing timing control means as shown in FIG.In the same manner as described above, when pre-ignition exceeding a predetermined level is detected in step 1 to step 32, control is performed to reduce the opening overlap amount of the intake / exhaust valves, and then pre-ignition exceeding the predetermined level is generated. It is determined whether or not a predetermined time has elapsed, and if it is determined that the elapsed time has elapsed, the intake air amount is decreased at the closing timing of the intake valve 3 in step 41 and step 42 as in the third embodiment. Control is performed by the valve drive device 2 so as to move in the direction.
[0045]
In this way, when pre-ignition is detected, by first reducing the open overlap amount of the intake and exhaust valves, the amount of burnt gas blown back is reduced to avoid pre-ignition, which is still not sufficient In this case, the pre-ignition can be avoided more reliably by controlling the closing timing of the intake valve so that the intake air amount is reduced to reduce the total gas amount in the cylinder.
[0046]
In the sixth embodiment shown in FIG. 21, the exhaust valve is detected when a pre-ignition level of a predetermined level or higher is detected in step 1, step 2, step 11, and step 12 as in the second embodiment. 4 is controlled so that it closes near the compression top dead center, and then it is determined in step 32 and step 33 whether or not the state where the pre-ignition of the predetermined level or more has occurred for a predetermined time or more has passed. In this case, in step 41 and step 42, the target closing timing of the intake valve 3 is changed and set in the direction in which the intake air amount decreases in the same manner as in the third embodiment, and the intake valve 3 is set at the target closing timing. The valve drive device 2 is controlled so as to be closed.
[0047]
In this way, when pre-ignition is detected, the amount of burnt gas blown back is first reduced to avoid pre-ignition, and if that is not enough, the exhaust valve closing timing control means controls the exhaust valve closing timing. By controlling the variable valve means so as to be close to the top dead center, the preburn is avoided by adding the action of reducing the amount of residual burned gas, and if that is not enough, the intake valve closing timing control means By controlling the variable valve operating means so that the intake valve closing timing is moved in the direction in which the intake air amount decreases, the action of reducing the total gas amount in the cylinder is added and the pre-ignition is more reliably avoided. First, avoid the pre-ignition by reducing the amount of residual burned gas so that the closing timing of the exhaust valve is close to top dead center, and if that is not enough, reduce the intake air amount to the closing timing of the intake valve. By controlling and reducing the total gas amount in the cylinder, pre-ignition can be avoided more reliably.
[0048]
Further, in the seventh embodiment shown in FIG. 22, when pre-ignition is detected in steps 1 to 34, first, the intake / exhaust valve opening overlap is first performed. Control is performed to reduce the amount, and control is performed to close the exhaust valve near the compression top dead center when preignition cannot be avoided. After performing the two controls, it is determined again in step 51 and step 52 whether or not the pre-ignition state continues for a predetermined time or more. In 53 and step 54, control is performed to move the intake valve closing timing so that the amount of intake air decreases.
[0049]
In this way, when pre-ignition is detected, the amount of burnt gas blown back is first reduced to avoid pre-ignition, and if that is not enough, the closing timing of the exhaust valve is brought closer to top dead center. In addition, preignition can be avoided by reducing the amount of residual burned gas, and if that is not enough, preignition can be avoided more reliably by reducing the total gas amount in the cylinder.
[0050]
In the embodiment of the above combination, the first control is to reduce the opening overlap amount of the intake / exhaust valves, the second is the control of the exhaust valve closing timing, and the third is the control of the intake valve closing timing. The control is performed because the decrease in the amount of residual burned gas due to the reduction in the amount of burned gas blowback is more effective than the static decrease in the amount of residual burned gas due to the control of the exhaust valve closing timing. In addition, the control of the closing timing of the intake valve is performed last because it involves a decrease in torque.
[0051]
In the above embodiment, the intake / exhaust valve opening timing and closing timing can be variably controlled using electromagnetic force. However, the lift characteristics of the intake / exhaust valve can be controlled with a mechanical configuration. Applicable to variable control. In this case, the present invention can be applied not only to a variable amount of lift and operating angle but also to a variable amount of phase. For example, when only the phase is variably controlled, if the opening timing is also advanced by increasing the closing timing of the intake valve at the time of pre-ignition detection, and the opening overlap amount of the intake / exhaust valve increases, the amount of exhaust is increased accordingly. Control that advances the valve closing timing may be performed.
[0052]
Similarly, in the case where control is performed so that the closing timing of the intake valve is advanced at the time of detecting the pre-ignition as shown in the above embodiment, the opening / closing operation time of the intake valve is fixed, so the opening timing of the intake valve is also high in the high speed range. In such a case, it is necessary to advance the closing timing of the exhaust valve so that the opening overlap amount of the intake / exhaust valve does not increase.
[0053]
Further, in the case where the opening / closing timing of the intake / exhaust valve can be arbitrarily variably controlled as in the present embodiment, the internal EGR may be performed by temporarily opening the exhaust valve during the intake stroke. However, with this configuration, when pre-ignition is detected, it is also possible to perform control to stop the internal EGR and lower the compression mixture temperature to avoid pre-ignition. This configuration is included in the invention that substantially reduces the open overlap amount of the intake and exhaust valves.
[Brief description of the drawings]
[Figure 1]Of the first embodimentThe block diagram which shows a structure and a function.
[Figure 2]Of the second embodimentThe block diagram which shows a structure and a function.
[Fig. 3]Of the third embodimentThe block diagram which shows a structure and a function.
[Fig. 4]Of the fourth embodimentThe block diagram which shows a structure and a function.
[Figure 5]Of the fifth embodimentThe block diagram which shows a structure and a function.
[Fig. 6]Of the sixth embodimentThe block diagram which shows a structure and a function.
[Fig. 7]Of the seventh embodimentThe block diagram which shows a structure and a function.
FIG. 8 is a system configuration diagram according to one embodiment.
FIG. 9 is a cross-sectional view showing a configuration of a valve driving device.
FIG. 10 is a flowchart illustrating control according to the first embodiment.
FIG. 11 is a diagram showing the relationship between the open overlap amount of the intake / exhaust valve and the residual burned gas amount.
FIG. 12 is a diagram showing the relationship between the amount of residual burned gas and the in-cylinder gas temperature near the compression top dead center.
FIG. 13 is a diagram showing the relationship between the in-cylinder gas temperature near the compression top dead center and the pre-ignition occurrence frequency.
FIG. 14 is a flowchart illustrating control according to the second embodiment.
FIG. 15 is a diagram showing the relationship between the amount of residual burned gas and the exhaust valve closing timing.
FIG. 16 is a flowchart showing control according to the third embodiment.
FIG. 17 is a diagram showing a relationship between intake valve closing timing and fresh air amount.
FIG. 18 is a diagram showing the relationship between the amount of fresh air and the amount of residual burned gas.
FIG. 19 is a flowchart showing control according to the fourth embodiment.
FIG. 20 is a flowchart showing control according to the fifth embodiment.
FIG. 21 is a flowchart showing control according to the sixth embodiment.
FIG. 22 is a flowchart showing control according to the seventh embodiment.
[Explanation of symbols]
      1 engine
      2 Valve drive
      3 Intake valve
      4 Exhaust valve
      6 Fuel injection valve
      7 Combustion chamber
      10 In-cylinder pressure sensor
      12 Control unit

Claims (7)

In an engine equipped with variable valve operating means for variably controlling the lift characteristics of the intake and exhaust valves,
Pre-ignition detection means for detecting pre-ignition;
An exhaust valve closing timing control means for controlling the variable valve means so that the closing timing of the exhaust valve is brought close to top dead center when pre-ignition is detected;
A pre-ignition prevention device for a variable valve engine characterized by comprising When the pre-ignition is detected, to claim 1, characterized in that configured to include an open overlap amount control means for controlling the variable valve means to reduce the opening overlap amount of the intake and exhaust valves The pre-ignition prevention device of the variable valve engine as described . When pre-ignition is detected, the variable valve means is first controlled so as to reduce the open overlap amount of the intake / exhaust valve by the open overlap amount control means, and then the exhaust valve closing timing control means controls the exhaust valve. 3. The pre-ignition prevention device for a variable valve engine according to claim 2 , wherein the variable valve means is controlled so that the closing timing approaches the timing at which the residual burned gas near the top dead center is minimized. An intake valve closing timing control means for controlling the variable valve operating means so as to move the closing timing of the intake valve in a direction in which the intake air amount decreases when pre-ignition is detected is characterized in that The preignition prevention device for a variable valve engine according to claim 1 . When pre-ignition is detected, the variable valve means is first controlled by the exhaust valve closing timing control means so that the closing timing of the exhaust valve approaches the timing at which the residual burned gas near the top dead center is minimized, and then 5. The variable valve engine pre-ignition according to claim 4 , wherein the variable valve operating means is controlled by the intake valve closing timing control means so as to move the intake valve closing timing in a direction in which the intake air amount decreases. Prevention device. An open overlap amount control means for controlling the variable valve means so as to reduce the open overlap amount of the intake / exhaust valve when pre-ignition is detected ;
An intake valve closing timing control means for controlling the variable valve operating means so as to move the closing timing of the intake valve in a direction in which the intake air amount decreases when pre-ignition is detected ;
The pre-ignition prevention device for a variable valve engine according to claim 1, comprising: When pre-ignition is detected, the variable valve means is first controlled so as to reduce the open overlap amount of the intake / exhaust valve by the open overlap amount control means, and then the exhaust valve closing timing control means controls the exhaust valve. The variable valve means is controlled so that the closing timing approaches the top dead center. Finally, the variable valve means is moved by the intake valve closing timing control means so that the intake valve closing timing is moved in the direction in which the intake air amount decreases. The pre-ignition prevention device for a variable valve engine according to claim 6 , wherein the pre-ignition prevention device is controlled.

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