JP5530641B2 - Knocking control device for spark ignition type internal combustion engine - Google Patents

Description

  The present invention relates to a knocking control device for a spark ignition type internal combustion engine.

  As a conventional spark ignition type internal combustion engine, there is one in which an effective compression ratio is made variable by controlling an opening / closing timing of an intake valve (see, for example, Patent Document 1).

JP-A-8-121301

  However, in the conventional spark ignition internal combustion engine, after the compression ratio is determined, the ignition timing is controlled to be retarded from the knocking limit based on the compression ratio and the operating state. For this reason, there is a problem in that a combination of compression ratio and ignition timing that provides optimum fuel consumption cannot be selected according to the driving state.

  The present invention has been made paying attention to such conventional problems, and enables selection of a combination of a compression ratio and an ignition timing that provides optimum fuel consumption according to the driving state while avoiding knocking. With the goal.

The present invention solves the above problems by the following means .

The present invention relates to a knock control apparatus for a spark ignition internal combustion institution having a compression ratio variable mechanism for varying the machinery compression ratio, the knocking detection means to detect knocking, operating at low speed and low load When knocking is detected, the ignition timing is retarded while the mechanical compression ratio is fixed to cancel knocking.When knocking is detected when operating at high rotation and high load, the ignition timing is knocking eliminating means to eliminate knock by reducing the mechanical compression ratio fixed while, characterized in that it comprises a.

  According to the present invention, knocking can be eliminated at a compression ratio and ignition timing that provide optimum fuel consumption according to the driving state.

It is a figure which shows the engine provided with the multi-link type piston stroke mechanism. It is a figure explaining the compression ratio change method by a multilink type piston stroke mechanism. It is the figure which showed the relationship between the ignition timing at the time of driving | running with a low load, and BSFC for every compression ratio. It is the figure which showed the relationship between the ignition timing at the time of driving | running with a high load, and BSFC for every compression ratio. It is a block diagram explaining the knocking avoidance control by 1st Embodiment. It is a flowchart explaining the knocking avoidance control by 1st Embodiment. It is a map for determining the knocking elimination means according to the driving state. It is a time chart explaining the operation | movement of knocking avoidance control at the time of a steady low load driving | operation. It is a time chart explaining the operation | movement of knocking avoidance control at the time of a steady high load driving | operation. It is a block diagram explaining the knocking avoidance control by 2nd Embodiment. It is a flowchart explaining the knocking avoidance control by 2nd Embodiment. It is a time chart explaining the operation | movement of knocking avoidance control at the time of transition. It is a flowchart explaining the knocking avoidance control by 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a view showing an engine 1 having a multi-link type piston stroke mechanism.

  The engine 1 includes a cylinder block 31 and a cylinder head 30 that covers the top of the cylinder block 31.

  In the cylinder block 31, a plurality of cylinders 31a are formed. A piston 60 is slidably fitted into the cylinder 31a. The cylinder head 30, the cylinder block 31, and the piston 60 define a pent roof type combustion chamber 40.

  An intake passage 41 and an exhaust passage 42 that open to the combustion chamber 40 are formed in the cylinder head 30, and an intake valve 43 that opens and closes the opening of the intake passage 41 and an exhaust valve 44 that opens and closes the opening of the exhaust passage 42 are provided. It is done. The cylinder head 30 is provided with a fuel injection valve 46. The fuel injection valve 46 injects fuel into the intake passage 41. Further, the cylinder head 30 is provided with an ignition plug 45. The spark plug 45 ignites the air-fuel mixture by blowing a spark at the center of the top wall of the combustion chamber 40.

  The multi-link piston stroke mechanism connects the piston 60 and the crankshaft 33 with two links (upper link 11 and lower link 12), and controls the lower link 12 with the control link 13 to change the compression ratio.

  The upper link 11 has an upper end connected to the piston 60 via the piston pin 21, and a lower end connected to one end of the lower link 12 via the upper pin 22. The piston 60 receives the combustion pressure and reciprocates in the cylinder 31 a of the cylinder block 31.

  One end of the lower link 12 is connected to the upper link 11 via the upper pin 22, and the other end is connected to the control link 13 via the control pin 23. In addition, the lower link 12 is inserted with the crank pin 33b of the crankshaft 33 in a substantially central connecting hole, and swings about the crank pin 33b as a central axis. The lower link 12 can be divided into left and right members. The crankshaft 33 includes a plurality of journals 33a, a crankpin 33b, and a counterweight 33c. The journal 33 a is rotatably supported by the cylinder block 31 and the ladder frame 34. The crank pin 33b is eccentric from the journal 33a by a predetermined amount, and the lower link 12 is swingably connected thereto. The counterweight 33c is provided in an arm portion that connects the journal 33a and the crankpin 33b, and removes the weight imbalance of the rotating portion.

  One end of the control link 13 is connected to the lower link 12 via the control pin 23, and the other end is connected to the control shaft 25 via the connection pin 24. The control link 13 swings around the connecting pin 24. Further, a gear is formed on the control shaft 25, and the gear meshes with a pinion 53 provided on the rotation shaft 52 of the actuator 51. The control shaft 25 is rotated by the actuator 51, and the connecting pin 24 moves.

  The controller 2 includes a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The controller 2 receives signals from various sensors that detect one operating state of the engine such as the knock sensor 71. The controller 2 controls the actuator 51 according to the operating state to change the compression ratio (mechanical compression ratio) of the engine.

  FIG. 2 is a view for explaining a compression ratio changing method by a multi-link type piston stroke mechanism.

  The multi-link piston stroke mechanism can change the compression ratio by rotating the control shaft 25 and changing the position of the connecting pin 24.

  For example, as shown in FIGS. 2 (A) and 2 (C), when the connecting pin 24 is set to the position P, the top dead center position (TDC) is increased and the compression ratio is increased.

  As shown in FIGS. 2B and 2C, when the connecting pin 24 is set to the position Q, the control link 13 is pushed upward, and the position of the control pin 23 is raised. Accordingly, the lower link 12 rotates counterclockwise around the crank pin 33b, the upper pin 22 is lowered, and the position of the piston 60 at the piston top dead center (TDC) is lowered. Therefore, the compression ratio becomes a low compression ratio.

  In the case of an engine in which the compression ratio can be changed as in the present embodiment, a method of reducing the compression ratio is conceivable as a method for solving the occurrence of knocking in addition to a method of retarding the ignition timing. Considering the fuel consumption, there are cases where it is better to retard the ignition timing and cases where it is better to lower the mechanical compression ratio depending on the driving state. This point will be described with reference to FIGS.

  FIG. 3 is a graph showing the relationship between the ignition timing and the net fuel consumption rate (Brake Specific Fuel Consumption; hereinafter referred to as “BSFC”) for each compression ratio when operating at a low load.

  Consider the case where knocking occurs when operating at a high compression ratio. When operating at a low load, as shown by the broken line in FIG. 3, when the ignition timing is retarded to the knocking limit and knocking is eliminated, the compression ratio is lowered as shown by the one-dot chain line in FIG. Thus, the BSFC becomes smaller than when the ignition timing is advanced to the knocking limit.

  In other words, when knocking occurs while driving at a low load, the fuel efficiency is improved by retarding the ignition timing while maintaining the compression ratio.

  FIG. 4 is a diagram showing the relationship between the ignition timing and the BSFC when operating at a high load for each compression ratio.

  Consider the case where knocking occurs while driving at high load. When operating at a high load, rather than delaying the ignition timing to the knocking limit as shown by the broken line in FIG. 4 and eliminating the knocking, the compression ratio is set to the knocking limit as shown by the one-dot chain line in FIG. The BSFC becomes smaller when the compression ratio is lowered.

  In other words, when knocking occurs while driving at a high load, the fuel efficiency is improved by lowering the compression ratio while maintaining the ignition timing.

  Therefore, in the present embodiment, switching is performed between controlling whether the ignition timing is controlled to eliminate knocking or controlling the compression ratio to cancel knocking according to the operating state. Hereinafter, this knocking avoidance control will be described.

  FIG. 5 is a block diagram illustrating knocking avoidance control according to the present embodiment.

  The engine speed and the engine load are input to the basic ignition timing calculation unit 101. The basic ignition timing calculation unit 101 calculates a basic ignition timing based on the engine speed and the engine load, and outputs the basic ignition timing.

  The basic compression ratio calculation unit 102 receives the engine speed and the engine load. The basic compression ratio calculation unit 102 calculates the basic compression ratio based on the engine rotation speed and the engine load.

  The knock determination unit 103 receives the output value of the knock sensor. Knock determination unit 103 compares the knock sensor output value with the knock determination level and outputs a determination result as to whether or not knocking has occurred.

  The correction value calculation unit 104 receives the determination result as to whether knocking has occurred, the engine rotation speed, and the engine load. When knocking has occurred, the correction value calculation unit 104 first detects the operating state from the engine speed and the engine load, and gives priority to either the ignition timing or the compression ratio according to the operating state. Decide whether to control. In accordance with the determination, a correction amount for the basic ignition timing (hereinafter referred to as “basic ignition timing correction amount”) and a correction amount for the basic compression ratio (hereinafter referred to as “basic compression ratio correction amount”) are calculated and output.

  The target ignition timing calculation unit 105 receives the basic ignition timing and the basic ignition timing correction amount. The target ignition timing calculation unit 105 calculates and outputs a target ignition timing based on the basic ignition timing and the basic ignition timing correction amount.

  The basic compression ratio and the basic compression ratio correction amount are input to the target compression ratio calculation unit 106. No. 9 table compression ratio calculation unit calculates and outputs a target compression ratio based on the basic compression ratio and the basic compression ratio correction amount.

  FIG. 6 is a flowchart illustrating the knocking avoidance control according to the present embodiment. The controller 2 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the engine.

  In step S1, the controller 2 calculates a basic ignition timing and a basic compression ratio according to the operating state.

  In step S2, the controller 2 determines whether knocking has occurred. When it is determined that knocking has occurred, the controller 2 proceeds to step S6. When it is determined that knocking has not occurred, the controller 2 proceeds to step S3.

  In step S3, the controller 2 sets the basic ignition timing to the target ignition timing.

  In step S4, the controller 2 sets the basic compression ratio to the target compression ratio.

  In step S5, the controller 2 controls the ignition timing to the target ignition timing, and controls the compression ratio to the target compression ratio.

  In step S6, the controller 2 determines knocking elimination means according to the operating state. Specifically, it is determined whether the engine is operating in the ignition timing control region or the compression ratio control region with reference to a map of FIG. 7 described later. When the engine is operating in the ignition timing control region, the controller 2 proceeds to step S7. On the other hand, when the engine is operating in the compression ratio control region, the process proceeds to step S9.

  In step S7, the controller 2 sets an ignition timing retarded from the basic ignition timing by a predetermined basic ignition timing correction amount as a target ignition timing.

  In step S8, the controller 2 sets the basic compression ratio to the target compression ratio.

  In step S9, the controller 2 sets the basic ignition timing to the target ignition timing.

  In step S10, the controller 2 sets a compression ratio obtained by reducing the basic compression ratio by a predetermined basic compression ratio correction amount as a target compression ratio.

  FIG. 7 is a map for determining knocking elimination means according to the driving state.

  As shown in FIG. 7, the operation is performed at a low rotation and a low load, but is an ignition timing control region, and the operation is performed at a high rotation or a high load is a compression ratio control region.

  FIG. 8 is a time chart for explaining the operation of knocking avoidance control during steady low-load operation. In order to clarify the correspondence with the flowchart, the step numbers of the flowchart will be described together.

  When knocking occurs at time t1 (FIG. 8 (D); Yes in S2), during steady low load operation, that is, when operating in the ignition timing control region (FIG. 8 (A); No in S6) The compression ratio remains the same (FIG. 8C; S8), and the ignition timing is retarded to the knock limit to eliminate knocking (FIGS. 8B, 8D, and S7).

  Similarly, when knocking occurs again at time t2, knocking is eliminated.

  FIG. 9 is a time chart for explaining the operation of the knocking avoidance control during the steady high load operation. In order to clarify the correspondence with the flowchart, the step numbers of the flowchart will be described together.

  When knocking occurs at time t11 (FIG. 8 (D); Yes in S2), in the case of steady high load operation, that is, when operating in the compression ratio control region (FIG. 8 (A); Yes in S6). The ignition timing remains the same (FIG. 8B; S9), and the compression ratio is lowered to the knock limit to eliminate knocking (FIGS. 8C and 8D; S10).

  Similarly, when knocking occurs again at time t12, knocking is eliminated.

  According to the present embodiment described above, when knocking occurs, the ignition timing is preferentially controlled according to the operating state to eliminate knocking, or the compression ratio is preferentially controlled to eliminate knocking. I decided to switch.

  Thereby, knocking can be eliminated at the compression ratio and ignition timing at which the optimum fuel consumption is achieved according to the driving state.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in that knocking is eliminated by controlling both the ignition timing and the compression ratio when knocking is detected when the operation state is a transient state. Hereinafter, the difference will be mainly described. In the following embodiments, the same reference numerals are used for portions that perform the same functions as those in the first embodiment described above, and repeated descriptions are omitted as appropriate.

  FIG. 10 is a block diagram illustrating the knocking avoidance control according to the present embodiment.

  The engine speed and the engine load are input to the transient state determination unit 201. The transient state determination unit 201 determines whether the operation state is a steady state or a transient state based on the engine rotation speed and the engine load, and outputs the determination result. The transient state determination unit 201 determines that the state is a transient state when there is a predetermined or greater torque fluctuation such as during rapid acceleration.

  A determination result as to whether knocking has occurred is input to the transient correction value calculation unit 202. When knocking has occurred, the transient correction value calculation unit 202 corrects the basic ignition timing during the transition (hereinafter referred to as “transient basic ignition timing correction amount”) and the correction amount for the basic compression ratio during the transient ( Hereinafter, “transient basic compression ratio correction amount”) is output.

  The switching unit 203 receives a determination result as to whether or not it is in a transient state, a basic ignition timing correction amount, a basic compression ratio correction amount, a transient basic ignition timing correction amount, and a transient basic compression ratio correction amount. Is done. The switching unit 203 outputs a basic ignition timing correction amount and a basic compression ratio correction amount if the operating state is a steady state. On the other hand, if the operating state is a transient state, a transient basic ignition timing correction amount and a transient basic compression ratio correction amount are output.

  FIG. 11 is a flowchart illustrating knocking avoidance control according to the present embodiment. The controller 2 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the engine.

  In step S21, the controller 2 determines whether the operation state is a steady state or a transient state. If the operating state is a steady state, the controller 2 proceeds to step S6, and if it is in a transient state, the controller 2 proceeds to step S22.

  In step S22, the controller 2 sets, as a target ignition timing, an ignition timing that is retarded from the basic ignition timing by a predetermined transient basic ignition timing correction amount.

  In step S <b> 23, the controller 2 sets a compression ratio obtained by reducing the basic compression ratio by a predetermined transient basic compression ratio correction amount as a target compression ratio.

  FIG. 12 is a time chart for explaining the operation of knocking avoidance control at the time of transition. In order to clarify the correspondence with the flowchart, the step numbers of the flowchart will be described together.

  If knocking occurs at the transition time t21 (FIGS. 12A and 12D; Yes at S2, Yes at S21), the ignition timing is retarded from the basic ignition timing by the transitional basic ignition timing correction amount (FIG. 12 ( B); S22), and the compression ratio is decreased from the basic compression ratio by a predetermined transient basic compression ratio correction amount to eliminate knocking (FIGS. 12C, 12D, and S23).

  According to the present embodiment described above, the same effects as those of the first embodiment can be obtained, and knocking at the time of transition can be reliably eliminated.

(Third embodiment)
Next, a third embodiment of the present invention will be described. The present embodiment is different from the first embodiment in that when the knocking frequency exceeds a predetermined value, the retard amount of the ignition timing or the decrease amount of the compression ratio is corrected. Hereinafter, the difference will be mainly described.

  FIG. 13 is a flowchart illustrating knocking avoidance control according to the present embodiment. The controller 2 executes this routine at a predetermined calculation cycle (for example, 10 ms) during operation of the engine.

  In step S31, the controller 2 determines whether or not the knocking frequency has become higher than a predetermined frequency. If the knocking frequency exceeds the predetermined frequency, the controller 2 moves the process to step S32, and if not, ends the current process.

  In step S32, the controller 2 updates the basic ignition timing value determined in advance according to the operating state to a new value. Specifically, the target ignition timing calculated in the previous step is set as the basic ignition timing used in the next calculation.

  In step S33, the controller 2 updates the basic compression ratio value determined in advance according to the operating state to a new value. Specifically, the target compression ratio calculated in the previous step is set as the basic compression ratio used in the next calculation.

  According to the present embodiment described above, when the knocking frequency is high, the basic ignition timing and the basic compression ratio values determined in advance according to the operating state are corrected. Thereby, in addition to obtaining the same effect as in the first embodiment, the frequency of knocking can be reduced.

  Note that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

1 Engine (spark ignition timing internal combustion engine)
DESCRIPTION OF SYMBOLS 11 Upper link 12 Lower link 13 Control link 25 Control shaft 31 Cylinder block 33 Crankshaft 51 Actuator 60 Piston 101 Basic ignition timing calculation part (basic value calculation means)
102 Basic compression ratio calculation unit (basic value calculation means)
104 Correction value calculation unit (correction value calculation means)
105 Target ignition timing calculation unit (target value calculation means)
106 Target compression ratio calculation unit (target value calculation means)
S1 Knock elimination means, basic value calculation means S2 Knock detection means S6 Knock elimination means S7 Knock elimination means, correction value calculation means, target value calculation means S8 Knock elimination means, target value calculation means S9 Knock elimination means, target value calculation means S10 Knocking canceling means, correction value calculating means, target value calculating means S21 Transient knocking canceling means S22 Transient knocking canceling means S23 Transient knocking canceling means S31 Knocking frequency calculating means S32 Basic value changing means S33 Basic value changing means

Claims (5)

A knocking control device for a spark ignition type internal combustion engine provided with a compression ratio variable mechanism that makes a mechanical compression ratio variable,
Knocking detection means for detecting knocking;
When knocking is detected when operating at low rotation and low load, knocking is canceled by retarding the ignition timing while fixing the mechanical compression ratio, and when operating at high rotation and high load. When detected, a knocking canceling means for canceling knocking by lowering the mechanical compression ratio while fixing the ignition timing;
A knocking control device for a spark ignition type internal combustion engine, comprising: The knock eliminating means is
Basic value calculating means for calculating a basic value of the ignition timing and compression ratio according to the operating state;
When knocking is detected when operating at low speed and low load, the ignition timing correction value is calculated. When knocking is detected when operating at high speed and high load, the mechanical compression ratio is corrected. Correction value calculating means for calculating a value;
When knocking is detected when operating at low rotation and low load, the basic value of the mechanical compression ratio is set as the target compression ratio, and the basic value of the ignition timing is corrected with the correction value of the ignition timing. When the ignition timing is calculated and knocking is detected when the engine is operating at a high rotation and high load, the basic value of the mechanical compression ratio is set to the mechanical compression ratio while the basic value of the ignition timing is set as the target ignition timing. Target value calculating means for calculating a target mechanical compression ratio by correcting with a correction value;
The knocking control device for a spark ignition type internal combustion engine according to claim 1, comprising: Knocking frequency calculating means for calculating the knocking frequency based on the detection result of knocking,
When the knocking frequency is higher than the predetermined frequency, the basic value of the ignition timing and compression ratio determined in advance according to the operating state is changed to the target value calculated at the time of the current calculation after the next calculation. Value changing means,
The knocking control device for a spark ignition type internal combustion engine according to claim 2, comprising: When knocking is detected in a transient state in which a torque fluctuation more than a predetermined value has occurred , the knocking canceling means is stopped, and a transient knocking canceling means for canceling knocking by controlling both the ignition timing and the compression ratio is provided. The knocking control device for a spark ignition type internal combustion engine according to any one of claims 1 to 3, wherein: The compression ratio variable mechanism is
A lower link supported rotatably on the crankshaft;
An upper link connecting the piston and the lower link;
A control shaft having an eccentric shaft portion that is rotatably supported by the cylinder block in parallel with the crankshaft and is eccentric with respect to the rotation axis;
A control link connecting the lower link and the eccentric shaft portion of the control shaft;
An actuator that rotates the control shaft within a predetermined angle range to change the position of the eccentric shaft portion of the control shaft;
The knocking control device for a spark ignition type internal combustion engine according to any one of claims 1 to 4, further comprising:

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