JP5456182B2 - Engine knock control device - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an engine knock (hereinafter referred to as “knock”) knock control device, and more particularly to an engine knock control device capable of determining knock that requires a retarded ignition timing and knock that does not require a retarded angle. About.

  In an internal combustion engine, that is, an engine, generally, the ignition timing is retarded (retarded) when it is determined that knocking has occurred, and conversely, when it is determined that knocking has not occurred, the ignition timing is gradually advanced. Ignition timing control is performed to optimize the ignition timing by making the angle. The knock control device described in Patent Document 1 detects vibration generated in the engine with a knock sensor, sets a knock determination level based on the detected vibration intensity distribution, and detects the detected vibration and knock determination level. And determining whether knocking has occurred or not, and when the vibration intensity deviates from a distribution estimated in advance with respect to the intensity distribution, a means for performing a fail process is provided.

  Further, in Patent Document 2, in view of the fact that engine noise is included in the output signal of the knock sensor, if this noise level exceeds the average value, knock control is performed in which this is regarded as a knock and the ignition timing is retarded. Some devices have been proposed that reduce operation with excessive amounts of retard.

JP 2002-188504 A Japanese Patent Laid-Open No. 1-100375

  There are two types of engine knock: one that occurs continuously and one that occurs once. Of these, for those that occur continuously, it is necessary to retard and optimize the ignition timing, but for those that occur only once and at a low frequency, even if the ignition timing is not retarded, There is little impact on the engine.

  In the knock control devices described in Patent Documents 1 and 2, regardless of the frequency of occurrence of knock, when the vibration level is greater than a predetermined value, even if the knock is a single shot, it is determined that the knock has occurred and the ignition timing is retarded. I do. At that time, immediately after the processing for the single knock, it is also necessary to return the ignition timing or advance the ignition timing. Such advance and retard processing imposes an extra burden on the microcomputer that constitutes the control device, and therefore it is desirable that the processing for retarding and advancing is small in a single knock determination. On the other hand, there are cases where it is better to retard the ignition timing from the standpoint of engine protection in the case of knocks that occur continuously even if the vibration level is low and the combustion is not determined to be a knock. There is also.

  The object of the present invention is to create a state in which knock combustion is not performed by judging over time from the viewpoint of engine protection, rather than determining knock by the magnitude of the vibration level of the knock in response to the above problem. An object of the present invention is to provide an engine knock control device.

  To achieve the above object, the present invention provides a knock sensor that is attached to an engine and outputs a voltage value corresponding to the vibration of the engine as detection data, and a plurality of the detection data input from the knock sensor within a predetermined time. And a data distribution detecting means for detecting a distribution for each voltage value of the detection data based on the voltage value, and a plurality of the detection data output within the predetermined time. An average means for calculating the average value of the knock level voltages of the detection data by dividing the total of the knock level voltages by the number of detection data output within the predetermined time, and the average value calculated by the average means A retard determination means for outputting an ignition retard command when the retard determination average value is greater than or equal to the retard determination average value, and the level of the detection data of the knock sensor is a predetermined knock determination voltage The retard determination means when there was an upper is characterized in that it is configured to be energized.

According to the present invention, even when the level of the detection data by the knock sensor exceeds the knock determination value, in the case of a single knock, the ignition timing is not immediately retarded, so unnecessary output suppression can be avoided. . In other words, the distribution of the number of occurrences of data detected by the knock sensor within a predetermined time is examined, and based on this distribution, a retard command is issued only when it is determined that a knock determination has occurred with a high detection data generation frequency. Thus, the ignition timing can be retarded.

  Accordingly, the retard command is not generated even if detection data of a single high level is generated, so that the ignition timing is not changed more than necessary, and the engine can always be operated at the optimal ignition timing. . In addition, the processing burden on the control device including the CPU can be reduced. Further, in the situation where knocking occurs frequently with a low level, the ignition timing is retarded in advance even when the occurrence of a high level of knocking is expected, so that the engine can be well protected.

It is a block diagram which shows the principal part function of the knock control apparatus which concerns on one Embodiment of this invention. It is a figure which shows the example of the detection signal by a knock sensor. It is a system configuration figure of the knock control device concerning one embodiment of the present invention. It is a figure which shows the generation number distribution of the detection signal for every knock level voltage. It is a flowchart of a data distribution detection process. It is a flowchart of a retard judgment process. It is a flowchart of the average value determination which concerns on 2nd Embodiment. It is a figure which shows distribution of the generation number of the detection data for every knock level voltage which concerns on 3rd Embodiment. It is a block diagram which shows the principal part function of the average value determination which concerns on 3rd Embodiment.

  FIG. 2 shows a result of an experiment in which a knock level, that is, an output voltage of a knock sensor described later is detected at a predetermined sampling interval. In FIG. 2, the horizontal axis represents the change amount (Δ finger pressure) of the cylinder pressure (finger pressure) of the engine, that is, the difference (absolute value) of the current value with respect to the previous value.

  In the figure, a mark indicated by a black circle is, for example, an output value of a knock sensor determined to have knocked by the method described in Patent Document 1, and a mark indicated by a black triangle is determined to have no knock by the same method. The output value of the knock sensor. As can be seen from this figure, there is a difference between the distribution of the detection signal determined to have knocked and the distribution of the detection signal determined to have no knock. That is, the detection signals determined as knocked are widely distributed, and the detection signals determined as not knocked are limited to a narrow range.

  Therefore, the present inventors detected the ignition timing with the knock sensor within a predetermined time without immediately retarding the ignition timing even when the output voltage of the knock sensor was a large value exceeding the knock determination voltage. Based on the signal distribution status, a retard necessity determination which will be described later is performed, and whether to retard is determined based on the determination result. Hereinafter, the present invention will be described according to embodiments.

  FIG. 3 is a system configuration diagram of the engine knock control apparatus according to the present embodiment. In FIG. 3, the engine 1 is a four-cycle water-cooled engine having a fuel injection device 2. The engine 1 includes a rotation speed sensor 4 for detecting the rotation speed of the crankshaft 3, a throttle sensor 6 for detecting the opening degree of the throttle valve 5, and an outer surface of an engine cylinder 7 having a water cooling jacket, in the vicinity of the combustion chamber 8. The knock sensor 9 is provided. The combustion chamber 8 is provided with an ignition device (ignition plug) 10.

  The engine control unit (ECU) 11 reads the detection signals of the rotational speed sensor 4 and the throttle sensor 6 and calculates the fuel injection amount by the fuel injection device 2 and the ignition timing by the ignition device 10, and the fuel injection device 2 and the ignition device 10 has a function of giving an instruction.

  The knock sensor 9 outputs a voltage signal corresponding to the vibration intensity of the cylinder 7 as detection data. The ECU 11 has a function of reading the detection data from the knock sensor 9 at a predetermined sampling interval, making a knock determination, and retarding the ignition timing of the ignition device 10 based on the result. The ECU 11 includes a microcomputer (CPU) 12, and a retard process based on the fuel injection amount, the ignition timing, or the knock determination is realized as a function of the CPU 12.

  FIG. 4 is a diagram illustrating an example of distribution of detection data (knock level voltage) of the knock sensor 9 at a predetermined time. The horizontal axis indicates the knock level voltage, and the vertical axis indicates the detection data for each knock level voltage at the predetermined time. The number of occurrences is shown respectively. In the figure, in the distribution A, a lot of detection data is detected only in the region where the knock level voltage is low, and the detection data is concentrated in a narrow range. As the distribution shifts from B to C, detection data is generated even in a region where the knock level voltage is high, and the detection data is distributed over a wide range, and the number of occurrences of the largest knock level voltage is the total detection data. The share is declining. That is, the peak P3 of the distribution C is lower than the peak values P1 and P2 of the distributions A and B.

  A distribution A represents a distribution of knock level voltages determined to have no knock in the sampling data shown in FIG. 2, and a distribution C represents a distribution of knock level voltages determined to have the knock. The distribution B is an example of an intermediate distribution C between the distributions A and B. In this embodiment, the distribution B is a distribution state in which it is determined that the retard is unnecessary.

  When a knock level voltage larger than knock determination value Vk is detected, it is determined that knocking occurs primarily. However, even if such a knock level voltage is detected, if it is generated only once, it is not regarded as a knock that requires a retard.

  Therefore, in the present embodiment, when the knock level voltage exceeds the knock determination value Vk, a knock level voltage (a peak region to be described later) where detection data is concentrated most in a predetermined time is detected. When the ratio of the number of detected data included in the peak area to the number of all detected data detected within the predetermined time is equal to or less than a preset ratio, for example, as shown in the distribution C, it is wide. Only when the detection data of the knock sensor 9 is distributed in the range, it is determined that the knock level voltage that needs to be retarded is detected.

  FIG. 1 is a block diagram showing the main functions of the CPU 12 according to the knock control device. In FIG. 1, the reading unit 13 reads a knock level voltage (detection data) that is detection data of the knock sensor 9 every time a clock CK is input. The read detection data is stored in the storage unit 14 and input to the knock determination unit 15. The storage unit 14 can store a predetermined number of detection data. When the input detection data reaches the predetermined number, the oldest detection data is deleted and rewritten with new detection data. Accordingly, the storage unit 14 stores the detection data read within the time determined by the read cycle and the number of stored data. Knock determination unit 15 compares knock determination value Vk with detection data, and outputs a knock detection signal when detection data is equal to or greater than the knock determination value.

  The data distribution detection unit 16 compares the detection data stored in the storage unit 14 with a plurality of knock level thresholds set in stages, and each detection data is divided into a plurality of knock level thresholds. Determine where in the knock level area. That is, the detection data corresponding to the knock level voltage is distributed for each knock level region, and the distribution of the detection data for each knock level region is determined.

  The peak area detection unit 17 detects a knock level area (peak area) that includes the most detection data among the knock level areas. In the ratio calculation unit 18, the number of detection data in the peak region detected by the peak region detection unit 17, that is, the number of detection data PDN included in the knock level region with the largest number of detection data occurrences is stored in the storage unit 14. The peak area data number ratio RATE is calculated by dividing by all the detected data numbers DN.

  The retard determination unit 19 compares the peak area data number ratio RATE with a predetermined retard determination ratio RATEref, and outputs a retard command when the peak area data number ratio is equal to or less than the retard determination ratio (RATE <RATEref).

  The retard command is input to the ignition timing control unit 20, and the ignition timing control unit 20 supplies an ignition signal retarded by a predetermined ignition angle to the ignition device 10.

  In the configuration of FIG. 1, the peak area detection unit 17, the ratio calculation unit 18, and the retard determination unit 19 are activated when a knock determination is made by the knock determination unit 15. However, at least only the retard determination unit 19 may be operated in response to the knock determination, and the peak region detection unit 17 and the ratio calculation unit 18 may be always operated.

  FIG. 5 is a flowchart showing the processing of the data distribution detection unit 16. In step S <b> 1, one piece of stored detection data is read from the storage unit 14. In step S2, it is determined whether or not the knock level L of the detected data is equal to or lower than the first threshold value L1. If step S2 is affirmative, it will progress to step S3 and will increment the counter value C1 of a 1st counter. If step S2 is negative, the process proceeds to step S4, and it is determined whether or not the knock level L of the detected data is equal to or lower than the second threshold L2 (L2> L1). If step S4 is affirmative, the process proceeds to step S5 to increment the counter value C2 of the second counter. If step S4 is negative, the process proceeds to step S6 to determine whether or not the knock level L of the detected data is equal to or lower than the third threshold L3 (L3> L2).

  If step S6 is affirmative, the process proceeds to step S7 to increment the counter value C3 of the third counter. If step S6 is negative, the knock level L is similarly compared with all the predetermined threshold values, and in step S8, the last threshold value Ln is compared with the knock level L of the detected data. That is, the number of thresholds is n. If the determination in step S8 is affirmative, the process proceeds to step S9 to increment the nth counter value Cn.

  If the determination in step S8 is negative, the process proceeds to step S10 to determine whether or not the knock levels of all the detection data in the storage unit 14 have been determined. Until all knock levels of the detection data in the storage unit 14 are determined, step S10 is negative and the process returns to step S1. When all the detection data in the storage unit 14 is determined, step S10 is affirmative and the process exits this flowchart.

  FIG. 6 is a flowchart showing the retard determination process. This processing corresponds to the processing of knock determination unit 15, peak region detection unit 17, ratio calculation unit 18, and retard determination unit 19. In step S11, it is determined whether or not the knock level voltage of the detection data read from the knock sensor 9 is equal to or higher than the knock determination value Vk. If step S11 is positive, the process proceeds to step S12. In step S12, the maximum counter value is extracted from the counter values C1 to Cn and is set as the detected data number PDN. That is, the number of detection data in an area where the most detection data is distributed among the areas divided by a plurality of threshold values is determined.

  In step S13, the peak data number ratio RATE is calculated by dividing the detection data number PDN by all the detection data numbers, that is, the total value DN of the counter values C1 to Cn. In step S14, it is determined whether or not the peak area data number ratio RATE is equal to or less than the retard determination ratio RATE. If step S14 is affirmative, it will progress to step S15 and will output a retard command. In step S16, the counter values C1 to Cn are reset to zero. If step S14 is negative, step S15 is skipped and the process proceeds to step S16.

  If the knock level voltage is less than the knock determination value Vk, step S12 is negative, and therefore the determination of whether or not the retard is necessary is not performed, and the process proceeds to step S16.

  Thus, in this embodiment, when the ratio of the number of detected data in the knock level region where the detected data is most concentrated to the total number of detected data stored in the storage unit 14 is smaller than a predetermined ratio, the retard is performed. It is determined that the required knock has occurred.

  Next, a second embodiment of the present invention will be described. As can be seen from the example of the distribution shown in FIG. 4, the distribution determined to have knock has a lower peak and the spread of the knock level voltage is larger than the distribution determined to have no knock. The average value of the distribution is also decreasing. Therefore, a retard command is generated when the average value of this distribution is equal to or less than the knock determination average value.

  FIG. 7 is a flowchart according to the second embodiment. In step S20, the number NNL of knock level regions including at least one detection data is detected. That is, the same processing as the processing in steps S1 to S10 is performed, and when this processing is completed, the number of counters that are “1” or more among the counter values C1 to Cn is detected. The number NNL of regions is larger in the distribution C than the distributions A and B shown in FIG.

  In step S21, the number of detected data Dn stored in the storage unit 14, that is, the number of detected data processed in the same manner as in steps S1 to S10, is divided by the number of knock level areas NNL detected in step S20. The average value DAVE is calculated.

  In step S22, if the determination in step S22 for determining whether the average value DAVE is equal to or less than the knock determination average value AVref is affirmative, the process proceeds to step S23 to output a retard command. In step S24, the counter values C1 to Cn are reset to zero. If step S22 is negative, step S23 is skipped and the process proceeds to step S24.

  Thus, when the knock level voltage is spread over a wide range as in distribution C shown in FIG. 4, the average value DAVE is lowered, and the detected data is in a narrow knock level voltage region as shown in distribution A in FIG. When the concentration is concentrated, the average value DAVE becomes high, so whether or not the retard is necessary is determined based on the magnitude of the average value DAVE.

  Subsequently, a third embodiment of the present invention will be described. In the second embodiment, the necessity of the retard is determined based on the average value of the number of occurrences of the detection data. In the third embodiment, the average value is calculated in the axial direction of the knock level voltage. This will be described with reference to FIG. FIG. 8 is a diagram showing the distribution of the number of occurrences of detection data for each knock level voltage, and is the same diagram as FIG. In FIG. 8, the average values calculated in the knock level voltage axis direction for the respective distributions A, B, and C are as indicated by symbols Aa, Ba, and Ca, and the distributions A and B without knock in the knock level voltage axis direction. It can be seen that the average value Ca in the knock level voltage direction of the distribution C with knock is higher than the average values Aa and Ba.

  Therefore, the average value of the knock level voltages of all the detection data stored in the storage unit 14 is calculated, and if this average value is equal to or greater than the knock determination voltage average value, a retard command is output.

  FIG. 9 is a block diagram illustrating functions of the CPU 12 according to the third embodiment. In FIG. 7, the voltage summing unit 21 sums all the detection data stored in the storage unit 14, that is, the knock level voltage value, and inputs the sum to the voltage averaging unit 22. The voltage averaging unit 22 divides the total voltage value V input from the voltage totaling unit 21 by all the detection data numbers DN stored in the storage unit 14 to calculate the knock level voltage average value Vav of the detection data. .

  The knock determination reference value storage unit 23 stores a reference value (retard determination average value) Vref for determining the knock level voltage average value Vav. The average value determination unit (retard determination means) 24 stores the reference value. The value Vref and the knock level voltage average value Vav are compared, and if the knock level voltage average value Vav is equal to or greater than the reference value Vref, a retard command is output.

  As described above, according to the present embodiment, when a knock level voltage equal to or higher than the knock determination value Vk is detected, the detected high knock level voltage is only suddenly generated based on the distribution of the knock level voltage. It is possible to determine whether there is a situation in which one of many continuous knock level voltages is likely to occur continuously. As a result, unnecessary retard processing can be eliminated.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 7 ... Cylinder, 9 ... Knock sensor, 10 ... Ignition device, 11 ... ECU, 12 ... Microcomputer (CPU), 15 ... Knock determination part, 16 ... Data distribution detection part, 17 ... Peak area | region detection part, 18 ... Ratio calculation unit, 19 ... Retard determination unit, 20 ... Ignition timing control unit

Claims (2)

A knock sensor (9) attached to the engine and outputting a voltage value corresponding to the vibration of the engine as detection data;
Average means for calculating the average value of the knock level voltages of the detection data by dividing the sum of the knock level voltages of the plurality of detection data output within the predetermined time by the number of detection data output within the predetermined time (22)
A retard determination means (19) for outputting an ignition retard command when the average value calculated by the averaging means is equal to or greater than the retard determination average value;
The retard determination means (19) is configured when the level of detection data of the knock sensor (9) is equal to or higher than a predetermined knock determination voltage, and the average value calculated by the averaging means is equal to or higher than the retard determination average value. An engine knock control device that outputs an ignition retard command.   The retard determination means (19) is configured to be activated when the level of detection data of the knock sensor (9) is equal to or higher than a predetermined knock determination voltage. Engine knock control device.

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