JP2016196850A - Knocking detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve knocking detection accuracy.SOLUTION: A knocking detection device receives input of detection signals from multiple detection means which are arranged at different locations on an internal combustion engine and output the detection signals according to oscillation of the internal combustion engine, and comprises knocking determination means which determines an occurrence of knocking on the basis of a plurality of detection signals output from the respective detection means. The knocking determination means has first determination means and second determination means. The first determination means determines whether or not each detection signal indicates the occurrence of knocking (S120). When the first determination means determines that all of the plurality of detection signals indicate the occurrence of knocking (S130: YES), the second determination means determines for at least two of those detection signals whether or not a time lag Dt between times tA and tB at which a predetermined characteristic indicative of knocking appeared is within a predetermined range, and determines that knocking has occurred when the time lag Dt is within the predetermined range (S140 to S200).SELECTED DRAWING: Figure 3

Description

  The present invention relates to an engine knocking detection device.

  There is a knock detection device that converts engine vibration into an electrical signal by a knock sensor and determines the presence or absence of knocking (that is, whether or not knocking has occurred) based on the signal from the knock sensor (for example, Patent Documents) 1). Knock is an abbreviation for knocking.

JP-A-5-340292

  In a conventional knock detection device, for example, when a vibration similar to the knocking characteristic occurs in a portion different from the cylinder in the engine, there is a high possibility of erroneous determination that knocking has occurred (that is, knocking has occurred). .

  Therefore, an object of the present invention is to improve the detection accuracy of knocking.

  The knocking detection device of the first invention receives detection signals from a plurality of detection means. Each of the plurality of detection means is arranged at a different position with respect to the internal combustion engine, and outputs a detection signal corresponding to the vibration of the internal combustion engine.

  The knocking detection device according to the first aspect of the present invention includes knocking determination that determines whether knocking has occurred in the internal combustion engine based on a plurality of detection signals from the respective detection means. The knocking determination means includes a first determination means and a second determination means.

The first determination unit determines, for each of the plurality of detection signals, whether the detection signal indicates the occurrence of knocking.
The second determination unit operates when it is determined by the first determination unit that all of the plurality of detection signals indicate the occurrence of knocking. Then, the second determination means has a time difference between the times at which the predetermined characteristics indicating knocking appear for at least two of the plurality of detection signals determined to indicate the occurrence of knocking by the first determination means. It is determined whether or not it is within a predetermined range, and it is determined that knocking has occurred in the internal combustion engine on the condition that the time difference is within the predetermined range.

  The time from when knocking occurs in the cylinder of the internal combustion engine until a predetermined feature indicating knocking appears in each detection signal from each detection means is determined by the distance between the knocking occurrence position and each detection means. For this reason, when knocking occurs, the time difference between the times at which the predetermined features appear in the detection signals is considered to be within a predetermined range. On the contrary, even if it is determined by the first determination means that all of the plurality of detection signals indicate the occurrence of knocking, if the time difference between at least two detection signals is not within the predetermined range, knocking occurs. It can be judged that it is not. In that case, for example, it is considered that vibration similar to the knocking characteristic occurred in a portion different from the cylinder in the engine.

  Therefore, the second determination unit operates when the first determination unit determines that all of the plurality of detection signals indicate the occurrence of knocking, and the time difference between at least two detection signals is predetermined. If it is not within the range, it is determined that knocking has not occurred. That is, whether or not knocking has actually occurred is confirmed based on whether or not the time difference is within a predetermined range. Therefore, according to this knocking detection device, it is possible to improve the determination accuracy of whether knocking has occurred (that is, the knocking detection accuracy).

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is a block diagram showing the structure of the electronic controller (ECU) of 1st Embodiment. It is explanatory drawing of a knock determination period. It is a flowchart showing the knocking determination process of 1st Embodiment. It is explanatory drawing explaining the case where it determines with knocking as an effect | action of the knock determination process of 1st Embodiment. It is explanatory drawing explaining the case where it determines with no knocking as an effect | action of the knock determination process of 1st Embodiment. It is a block diagram showing the structure of the electronic controller (ECU) of 2nd Embodiment. It is a flowchart showing the knocking determination process of 2nd Embodiment.

  Hereinafter, an electronic control device (hereinafter referred to as ECU) according to an embodiment to which the present invention is applied will be described. The ECU of the present embodiment is an ECU that controls the engine (internal combustion engine) of the vehicle. Hereinafter, matters relating to detection of knocking will be described. Note that ECU is an abbreviation for “Electronic Control Unit”.

[First Embodiment]
As shown in FIG. 1, the engine 2 controlled by the ECU 1 of the first embodiment has, for example, four cylinders # 1 to # 4.

  The cylinder block (engine block) of the engine 2 includes two knocking sensors (hereinafter also simply referred to as sensors) 3A-1, 3B-1 to 3A-4, 3B-4 for each of the cylinders # 1 to # 4. Are provided.

  In this example, the sensors 3A-1, 3B-1 to 3A-4, 3B-4 are non-resonant sensors that convert vibration of the engine 2 into voltage by a built-in piezoelectric element. Therefore, the output signals of the sensors 3A-1, 3B-1 to 3A-4, 3B-4 (hereinafter referred to as sensor signals) are attached to the sensors 3A-1, 3B-1 to 3A-4, 3B-4. This is a voltage signal representing the vibration at the position. Each of the sensors 3A-1, 3B-1 to 3A-4, 3B-4 corresponds to detection means, and the sensor signal corresponds to a detection signal.

  In addition, in the code | symbol (3A-1, 3B-1 to 3A-4, 3B-4) of a sensor, when the number following "-" is set to n (n is either 1-4), "3A-n" , “3B-n” means that the sensor to which the symbol is attached corresponds to cylinder #n. Further, in the following description, when the cylinders # 1 to # 4 are not particularly distinguished, “#n” is used as a cylinder code, and “#n” is a code of two sensors provided for the cylinder #n. 3A-n "and" 3B-n "are used.

  A pair of sensors 3A-1, 3B-1 to 3A-4 and 3B-4 for each cylinder # 1 to # 4 sandwich each cylinder # 1 to # 4 and each cylinder # 1. Are provided at positions symmetrical to the central axis of # 4. Further, the positional relationship of the sensors 3A-1, 3B-1 to 3A-4, 3B-4 with respect to the respective cylinders # 1 to # 4 is the same in all the cylinders # 1 to # 4. Of course, such a sensor arrangement is merely an example.

Sensor signals from the sensors 3A-1, 3B-1 to 3A-4, 3B-4 are input to the ECU 1.
The ECU 1 includes two multiplexers (MPX) 5A and 5B, two amplifiers (amplifier circuits) 7A and 7B, two filters 9A and 9B, and a microcomputer (hereinafter referred to as a microcomputer) that controls the operation of the ECU 1. 11).

  The multiplexer 5A receives sensor signals from one of the sensors 3A-1, 3A-2, 3A-3, 3A-4 for the cylinders # 1 to # 4. Then, the multiplexer 5A selects any one of the sensor signals from the sensors 3A-1 to 3A-4 according to a command from the microcomputer 11 and outputs the selected signal to the amplifier 7A.

  The multiplexer 5B receives sensor signals from the other sensors 3B-1, 3B-2, 3B-3, and 3B-4 for the cylinders # 1 to # 4. Then, the multiplexer 5B selects any one of the sensor signals from the sensors 3B-1 to 3B-4 in response to a command from the microcomputer 11 and outputs the selected signal to the amplifier 7B.

  Each of the amplifiers 7A and 7B amplifies and outputs the sensor signal input from each of the multiplexers 5A and 5B. The output of the amplifier 7A is input to the filter 9A, and the output of the amplifier 7B is input to the filter 9B.

  The filter 9A is a band-pass filter that extracts and outputs a knocking frequency component (vibration frequency peculiar to knocking, for example, 5 to 15 kHz) from the sensor signal input from the amplifier 7A. The output of the filter 9A is input to the microcomputer 11.

  The filter 9B is also a band-pass filter that extracts and outputs a knocking frequency component from the sensor signal input from the amplifier 7B. The output of the filter 9B is also input to the microcomputer 11. In this example, the filters 9A and 9B are analog circuit filters, but the filters 9A and 9B may be digital filters.

  The microcomputer 11 includes a CPU 13, a ROM 15 in which programs and data executed by the CPU 13 are stored, a RAM 17 in which calculation results of the CPU 13 are stored, an A / D converter (ADC) 19, and a register 21. .

  The ECU 1 is connected to an injector 23 that injects fuel into each of the cylinders # 1 to # 4 and an igniter 25 that ignites each of the cylinders # 1 to # 4. In FIG. 1, one injector 23 and one igniter 25 are shown, but they are actually provided for each of the cylinders # 1 to # 4.

  In the ECU 1, any of sensor signals from the sensors 3A-1 to 3A-4 is input to the filter 9A via the multiplexer 5A and the amplifier 7A, and the sensor signal that has passed through the filter 9A is input to the microcomputer 11. Is done. Similarly, any of the sensor signals from the sensors 3B-1 to 3B-4 is input to the filter 9B via the multiplexer 5B and the amplifier 7B, and the sensor signal passing through the filter 9B is input to the microcomputer 11. The The arrangement order of the amplifiers 7A and 7B and the filters 9A and 9B may be reversed.

  Then, the microcomputer 11 performs A / D conversion on each sensor signal that has passed through each of the filters 9A and 9B by the A / D converter 19 and whether knocking has occurred in the engine 2 using the A / D conversion result. Whether or not (that is, the presence or absence of knocking) is determined. In the present embodiment, the microcomputer 11 determines the presence or absence of knocking for each of the cylinders # 1 to # 4. Hereinafter, the sensor signal that has passed through each of the filters 9A and 9B is also referred to as a post-filter sensor signal. The A / D conversion result of the filtered sensor signal is also referred to as a filtered sensor value. The post-filter sensor value indicates the strength of knocking.

  Next, a process performed by the microcomputer 11 to determine the presence or absence of knocking will be described. Note that the processing performed by the microcomputer 11 is actually realized by the CPU 13 executing the program in the ROM 15.

  The microcomputer 11 sets a period during which knocking may occur for each of the cylinders # 1 to # 4 as a knocking determination period. The knocking determination period is a period for which the presence or absence of knocking is determined. For example, as indicated by the hatched portion in FIG. 2, a period corresponding to a predetermined crank angle from the ignition timing by the igniter 25 is set as the knocking determination period Kp for each of the cylinders # 1 to # 4. The period corresponding to the predetermined crank angle is a period required for the crankshaft of the engine 2 to rotate by the predetermined crank angle.

  In FIG. 2, the waveform of the “igniter” stage represents the ignition pulse to the igniter 25, and the fall timing of the ignition pulse from high (ON) to low (OFF) is the ignition timing. . The same applies to FIGS. 4 and 5 described later. Further, for example, the firing order of the cylinders # 1 to # 4 is “# 1 → # 2 → # 4 → # 3”. Of the three hatched portions in FIG. 2, for example, the left hatched portion is the knocking determination period Kp of the cylinder # 1, and the central hatched portion is the knocking determination period Kp of the cylinder # 2. The hatched portion is the knocking determination period Kp of cylinder # 4.

  In the knocking determination period Kp of each cylinder # 1 to # 4, the microcomputer 11 multiplexes the sensor signals from the sensors 3A-n and 3B-n provided for the cylinder #n corresponding to the current knocking determination period Kp. 5A and 5B are selected. Further, in the knocking determination period Kp, the microcomputer 11 performs A / D conversion for each of the post-filter sensor signals output from the filters 9A and 9B at regular intervals, and at the regular time A The / D conversion result (filtered sensor value) is sequentially stored in the RAM 17. The fixed time, which is the A / D conversion interval of the sensor signal after filtering, is set to a sufficiently short time so that the waveform of the sensor signal after filtering can be grasped.

  For this reason, at the end of the knocking determination period Kp of the cylinder #n, the RAM 17 stores the sensor values after filtering for each sensor signal from the sensors 3A-n and 3B-n corresponding to the cylinder #n. Thus, only the knocking determination period Kp is stored.

The microcomputer 11 executes the knocking determination process of FIG. 3 every time the knocking determination period Kp of each cylinder # 1 to # 4 ends.
The knocking determination process of FIG. 3 is a process for determining the presence or absence of knocking for the cylinder corresponding to the completed knocking determination period Kp. Hereinafter, the case where the knocking determination period Kp of the cylinder #n has ended will be described. That is, the cylinder #n will be described as determining whether or not knocking has occurred. Hereinafter, the sensor signal from the sensor 3A-n of the cylinder #n is referred to as a sensor signal A, and the sensor signal A that has passed through the filter 9A is referred to as a post-filter sensor signal A. The A / D conversion result of A is referred to as a post-filter sensor value A. Similarly, the sensor signal from the sensor 3B-n of the cylinder #n is referred to as a sensor signal B, and the sensor signal B that has passed through the filter 9B is referred to as a post-filter sensor signal B. The A / D conversion result is referred to as a post-filter sensor value B.

  As shown in FIG. 3, when the microcomputer 11 starts the knocking determination process, first, in S110, the microcomputer 11 sets a determination flag indicating the knocking presence / absence determination result to “0” indicating “no knocking”. That is, the determination flag is initialized. The determination flag is 1-bit data stored in the register 21, for example.

  In step S120, the microcomputer 11 determines whether or not the occurrence of knocking (with knocking) is indicated for each of the sensor signals A and B from the sensors 3A-n and 3B-n of the cylinder #n. . For example, for the sensor signal A, the microcomputer 11 has a filtered sensor value A equal to or greater than a predetermined knocking determination value Nth among the filtered sensor values A for the knocking determination period Kp stored in the RAM 17. Determine whether or not. If there is a post-filter sensor value A equal to or greater than the knock determination value Nth, it is determined that the sensor signal A indicates the occurrence of knocking. Similarly, for the sensor signal B, the microcomputer 11 determines whether or not there is a filtered sensor value B equal to or greater than the knocking determination value Nth among the filtered sensor values B for the knocking determination period Kp stored in the RAM 17. judge. If there is a post-filter sensor value B equal to or greater than the knock determination value Nth, it is determined that the sensor signal B indicates the occurrence of knocking.

  In the next S130, the microcomputer 11 determines whether or not all the determination results for the sensor signals A and B in S120 are “knocked”. The fact that the determination results for the sensor signals A and B are all “knocked” means that it is determined in S120 that all of the sensor signals A and B indicate the occurrence of knocking.

  If the microcomputer 11 makes a negative determination (determined NO) in S130 (that is, if one of the sensor signals A and B does not indicate the occurrence of knocking), the microcomputer 11 directly performs the knocking determination process. Exit.

  If the microcomputer 11 makes an affirmative determination (determined as YES) in S130 (that is, if all of the sensor signals A and B indicate the occurrence of knocking), the microcomputer 11 proceeds to S140 and sets the determination flag to “ Set to “1” which indicates “knocking”. However, the setting of the determination flag in S140 is a setting based on provisional determination (that is, provisional setting).

  In step S150, the microcomputer 11 detects the time at which a predetermined feature indicating knocking appears (hereinafter referred to as a feature time) for each of the sensor signals A and B in the knocking determination period Kp.

  In the present embodiment, for example, the predetermined characteristic is that the post-filter sensor signals A and B are maximum values (in other words, peak values). For this reason, in S150, the microcomputer 11 detects the time when each of the post-filter sensor signals A and B becomes the maximum value as the characteristic time.

  Specifically, the microcomputer 11 detects the maximum value from the filtered sensor value A for the knocking determination period Kp stored in the RAM 17, and performs A / D conversion of the filtered sensor value A that is the maximum value. Is stored as the characteristic time tA for the sensor signal A. Similarly, the microcomputer 11 detects the maximum value from the filtered sensor value B for the knocking determination period Kp stored in the RAM 17, and performs A / D conversion of the filtered sensor value B, which is the maximum value. This time is stored as the characteristic time tB for the sensor signal B.

  In step S160, the microcomputer 11 calculates a time difference between the characteristic times tA and tB detected in step S150 (specifically, an absolute value of the time difference = | tA−tB |) Dt, and then the process proceeds to step S170.

In S170, the microcomputer 11 sets a knocking presence / absence determination time R used in the next S180. The knocking presence / absence determination time R will be described later.
In S180, the microcomputer 11 determines whether or not the time difference Dt calculated in S160 is equal to or less than the knocking determination time R. Since the minimum value of the time difference Dt is 0, the determination in S180 determines whether or not the time difference Dt is within the range of “0 to R”.

  If the microcomputer 11 determines in S180 that the time difference Dt is equal to or less than the knocking determination time R, the microcomputer 11 determines that knocking has actually occurred for the cylinder #n and changes the setting of the determination flag. If not, the process proceeds to S200.

  If the microcomputer 11 determines in S180 that the time difference Dt is not equal to or less than the knocking determination time R, that is, if the time difference Dt is not within the range of “0 to R”, knocking has not occurred. Determination is made and the process proceeds to S190. In S190, the microcomputer 11 rewrites the determination flag from “1” to “0”, and then proceeds to S200.

  In S200, the microcomputer 11 determines whether or not the determination flag is “1”. If the determination flag is not “1”, the microcomputer 11 ends the knocking determination process as it is, but if the determination flag is “1”. If so, the process proceeds to S210. In S210, the microcomputer 11 performs, for example, a process of retarding the ignition timing for the engine 2 as a process for eliminating the knocking, and then ends the knocking determination process.

Here, the knocking presence / absence determination time R used for the determination in S180 will be described.
The time from when knocking occurs in cylinder #n to when a predetermined characteristic indicating knocking appears in each of sensor signals A and B (in this embodiment, until sensor signals A and B after filtering reach a maximum value) Is determined by the distance between the knocking occurrence position and each of the sensors 3A-n and 3B-n. Therefore, when knocking occurs in the cylinder #n, the time difference Dt calculated in S160 is considered to be within a predetermined range determined by the positional relationship between the cylinder #n and the sensors 3A-n and 3B-n. Conversely, even if it is determined in S120 that all of the sensor signals A and B indicate that knocking has occurred, if the time difference Dt calculated in S160 is not within the predetermined range, knocking has not occurred. Judgment can be made.

  In this embodiment, since the distances from the center axis of the cylinder #n to the sensors 3A-n and 3B-n are equal, the minimum value of the time difference Dt when knocking occurs in the cylinder #n is 0. . Therefore, the knocking presence / absence determination time R is set to the maximum value of the time difference Dt when knocking occurs in the cylinder #n. Such knocking presence / absence determination time R can be determined by theoretical calculation and / or experiment. In the present embodiment, the ROM 15 stores a knocking presence / absence determination time R determined in advance by theoretical calculation or experiment, and the microcomputer 11 performs a process of reading the knocking presence / absence determination time R from the ROM 15 in S170.

  In the present embodiment, the positional relationship of the sensors 3A-1, 3B-1 to 3A-4, 3B-4 with respect to the respective cylinders # 1 to # 4 is the same in all the cylinders # 1 to # 4. The knocking presence / absence determination time R is the same value for all the cylinders # 1 to # 4. On the other hand, for example, when cylinders # 1 to # 4 have different vibration transmission speeds to sensors 3A-1, 3B-1 to 3A-4, 3B-4, or sensors 3A-1, 3B-1 to 3A. If the positional relationship with −4, 3B-4 is different, in S170, the knocking presence / absence determination time R may be set to a different value for each of the cylinders # 1 to # 4.

  Next, the operation of the knocking determination process (FIG. 3) will be described with reference to FIGS. 4 and 5, the waveform of the “sensor A” stage represents the filtered sensor signal A, and the waveform of the “sensor B” stage represents the filtered sensor signal B.

  When knocking occurs in the cylinder #n, as shown in FIG. 4, in the knocking determination period Kp for that cylinder #n, both the filtered sensor signal A and the filtered sensor signal B are knocked determination values. Nth or more. Therefore, in the knocking determination process of FIG. 3, it is determined in S120 that all of the sensor signals A and B indicate the occurrence of knocking, YES is determined in S130, and the determination flag is “ Set to 1 ". Further, in this case, as shown in FIG. 4, the time difference Dt (= | tA−tB |) calculated in S160 of FIG. For this reason, in the knocking determination process of FIG. 3, it is determined YES in S180, and the determination flag remains “1”. That is, it is finally determined that knocking has occurred for cylinder #n. As a result, a process for retarding the ignition timing is performed to eliminate knocking (S210).

  On the other hand, in the knocking determination period Kp of the cylinder #n, for example, it is assumed that vibration similar to the knocking characteristic occurs outside the cylinder #n. As shown in FIG. 5, it is assumed that both the filtered sensor signal A and the filtered sensor signal B in the knocking determination period Kp are equal to or greater than the knocking determination value Nth. Then, in the knocking determination process of FIG. 3, it is determined in S120 that all of the sensor signals A and B indicate the occurrence of knocking, YES is determined in S130, and the determination flag is “1” in S140. "Is set.

  However, as shown in FIG. 5, if the time difference Dt (= | tA−tB |) calculated in S160 of FIG. 3 is larger than the knocking presence / absence determination time R, the knocking determination process of FIG. In S190, the determination flag is rewritten from “1” to “0”. That is, the determination result of the presence / absence of knocking is changed to “no knocking”, and it is not finally determined that knocking is present (it is determined that knocking is not present). As a result, the ignition timing is not retarded. For example, it is assumed that vibration similar to the knocking characteristic occurs on the side opposite to the cylinder #n side as viewed from the sensor 3A-n or the sensor 3B-n of the cylinder #n, and YES is determined in S130 of FIG. However, it is possible to prevent NO from being determined in S180 and erroneously determining that knocking has occurred.

  Therefore, according to the ECU 1 of the present embodiment, it is possible to improve the determination accuracy (knocking detection accuracy) of whether or not knocking has occurred. As a result, the engine 2 can be controlled with a minimum knocking avoidance control (ignition timing control), which leads to an improvement in fuel consumption and output. In general, the knocking determination adopts a method of determining that there is knocking when it is determined that there is knocking in a plurality of combustion cycles in consideration of erroneous determination due to noise. It is also possible to determine that knocking is present in one combustion cycle. For this reason, knocking can be detected earlier and damage to the engine 2 due to knocking can be more reliably avoided.

  Further, the ECU 1 extracts the knocking frequency components from the sensor signals output from the sensors 3A-1, 3B-1 to 3A-4, 3B-4 by the filters 9A, 9B. In the knocking determination process of FIG. The filtered sensor signals that have passed through the filters 9A and 9B are processed. For this reason, only signals in the frequency band generated by knocking among signals of various frequencies can be processed. Therefore, useless calculation can be eliminated and the knocking determination time can be shortened.

  Further, the ECU 1 detects a feature that the sensor signal (filtered sensor signal in the present embodiment) has reached the maximum value as the “predetermined feature indicating knocking” in the sensor signal. Since the process of detecting the maximum value is relatively easy, the processing load for knocking determination can be reduced.

  In the present embodiment, a plurality (two in this example) of sensors 3A-n and 3B-n are provided for each cylinder #n of the engine 2. In the knocking determination process, whether or not knocking has occurred is determined for each cylinder #n based on the sensor signals A and B from the sensors 3A-n and 3B-n corresponding to the cylinder #n. Therefore, the distance between the knocking source and the sensor can be reduced, and the presence / absence of knocking can be determined more accurately based on the sensor signal having a good S / N ratio related to knocking. In addition, there is an advantage that it is difficult to be influenced by the cylinders.

[Second Embodiment]
Next, the ECU of the second embodiment will be described. In addition, the same code | symbol as 1st Embodiment is used about the component and process similar to 1st Embodiment.

The second embodiment differs from the first embodiment in the following items <1> to <3>.
<1> As shown in FIG. 6, the cylinder block of the engine 2 controlled by the ECU 31 of the second embodiment is provided with two sensors 3A and 3B at both ends in the direction in which the cylinders # 1 to # 4 are arranged. . The two sensors 3A and 3B are the same sensors as the sensors 3A-1, 3B-1 to 3A-4 and 3B-4 of the first embodiment, but are common to all the cylinders # 1 to # 4. It is provided as.

  Also in the second embodiment, the output signals of the sensors 3A and 3B are referred to as sensor signals. In the second embodiment, the sensor signal from the sensor 3A is referred to as a sensor signal A, and the sensor signal from the sensor 3B is referred to as a sensor signal B.

  <2> The ECU 31 of the second embodiment is not provided with the multiplexers 5A and 5B. The sensor signal A from the sensor 3A is input to the microcomputer 11 via the amplifier 7A and the filter 9A, and the sensor signal B from the sensor 3B is input to the microcomputer 11 via the amplifier 7B and the filter 9B.

  For this reason, the microcomputer 11 does not perform the selection switching control for the multiplexers 5A and 5B. Then, during the knocking determination period Kp of each cylinder # 1 to # 4, the microcomputer 11 performs A / D conversion for each of the filtered sensor signals A and B output from the filters 9A and 9B at regular intervals. At the same time, the filtered sensor values A and B, which are the A / D conversion results at regular intervals, are sequentially stored in the RAM 17.

<3> The microcomputer 11 executes the knocking determination process of FIG. 7 instead of the knocking determination process of FIG.
Compared to the knocking determination process of FIG. 3, the knocking determination process of FIG. 7 is provided with S175 instead of S170, and is provided with S182 to S188 instead of S180.

  In S120, S130, S150, and S160 in the knocking determination process of FIG. 7, each sensor signal A, 3B from the sensors 3A, 3B, regardless of which knocking determination period Kp of the cylinders # 1 to # 4 has ended. For B, the same processing as in the first embodiment is performed.

In the knocking determination process of FIG. 7, the microcomputer 11 proceeds to S175 after S160.
In S175, the microcomputer 11 sets values corresponding to the cylinders subject to knocking determination as the two knocking presence / absence determination times R1 and R2 used in the subsequent determination in S188.

  The cylinder that is subject to knocking determination is a cylinder that is subject to knocking determination among cylinders # 1 to # 4, and is a cylinder that has completed the knocking determination period Kp this time. R1 of knocking presence / absence determination times R1 and R2 is the minimum value of the time difference Dt when knocking occurs in the cylinder subjected to knocking determination, and R2 of knocking presence / absence determination times R1 and R2 is the knocking determination target. This is the maximum value of the time difference Dt when knocking occurs in the cylinder. The time difference Dt is the time difference Dt calculated in S160.

  Such knocking presence / absence determination times R <b> 1 and R <b> 2 are also determined by theoretical calculation and / or experiment and stored in the ROM 15. Therefore, in S175, the microcomputer 11 reads the knocking presence / absence determination times R1 and R2 prepared for the knocking determination target cylinder from the ROM 15.

  The microcomputer 11 proceeds to S182 after S175, determines whether or not the cylinder subject to knocking determination is any one of the cylinders # 1 and # 2, and if the determination is affirmative (determined as YES), the microcomputer 11 performs S184. Proceed to

  In S184, the microcomputer 11 compares the feature times tA and tB for the sensor signals A and B detected in S150 to determine whether or not “tA <tB” (that is, the feature time tA is the feature time tB). If “tA <tB”, the process proceeds to S188.

If the microcomputer 11 makes a negative determination (NO) in S182, that is, if the cylinder subjected to knocking determination is any one of the cylinders # 3 and # 4, the microcomputer 11 proceeds to S186.
In S186, the microcomputer 11 compares the feature times tA and tB for the sensor signals A and B detected in S150 to determine whether or not “tA> tB” (that is, the feature time tA is the feature time tB). If “tA> tB”, the process proceeds to S188.

In S188, the microcomputer 11 determines whether or not the time difference Dt calculated in S160 is within the range from R1 to R2 set in S175.
If the microcomputer 11 determines in S188 that the time difference Dt is within the range of “R1 to R2”, the microcomputer 11 determines that knocking has actually occurred for the cylinder subjected to knocking determination, and the determination flag Without changing the setting, the process directly proceeds to S200 described above.

  If the microcomputer 11 determines in S188 that the time difference Dt is not within the range of “R1 to R2”, the microcomputer 11 determines that knocking has not occurred, and proceeds to S190. In S190, the determination flag is determined. After rewriting to “0”, the process proceeds to S200.

  On the other hand, if the microcomputer 11 determines that “tA <tB” is not satisfied in S184 or if it is determined that “tA> tB” is not satisfied in S186, the microcomputer 11 proceeds to S190, and sets a determination flag in S190. After rewriting to “0”, the process proceeds to S200.

  That is, in the second embodiment, since the two sensors 3A and 3B provided in the engine 2 are used in common for each of the cylinders # 1 to # 4, when the knocking determination target cylinder is changed, the knocking determination target is changed. The positional relationship between the cylinder and the sensors 3A, 3B changes.

  For this reason, the microcomputer 11 switches and sets the knocking presence / absence determination times R1 and R2 used for the determination of the time difference Dt in S188 for each cylinder subjected to knocking determination by the process of S175.

Therefore, according to the ECU 31 of the second embodiment, the knocking presence / absence determination for each of the cylinders # 1 to # 4 can be accurately performed only by providing the engine 2 with the two sensors 3A and 3B.
Further, the position of the sensor 3A is closer to the position of the sensor 3B when viewed from the cylinders # 1 and # 2, and the position of the sensor 3B is closer to the position of the sensor 3A when viewed from the cylinders # 3 and # 4.

  Therefore, when either of the cylinders # 1 and # 2 is the knocking determination target, if knocking occurs in the cylinder for the knocking determination, the characteristic time tA for the sensor signal A is It should be before the characteristic time tB.

  If any of cylinders # 3 and # 4 is knocking determination target and if knocking occurs in the cylinder for knocking determination, the characteristic time tA for sensor signal A is It should be later than the characteristic time tB.

  For this reason, when either of the cylinders # 1 and # 2 is the knocking determination target (S182: YES), the microcomputer 11 determines whether or not “tA <tB” in S184, and “tA If it is not <tB ”(S184: NO), it is determined that knocking has not occurred. Similarly, when any of the cylinders # 3 and # 4 is the knocking determination target (S182: NO), the microcomputer 11 determines whether or not “tA> tB” in S186, and “tA” If it is not> tB ”(S186: NO), it is determined that knocking has not occurred.

  As described above, in S182, S184, and S186 in FIG. 7, a contradiction between which of the feature times tA and tB comes first is also detected, and erroneous determination that knocking is present is prevented. In other words, the condition of which feature time tA or tB comes first is also added to the condition for determining that knocking is present. In the second embodiment, it is determined whether or not the total time difference between S182 to S186 and S188 is within a predetermined range with a time difference with a positive / negative sign of “tA−tB”. Therefore, the presence / absence of knocking can be determined with higher accuracy.

[Other embodiment 1]
For example, in the first and second embodiments, the “predetermined feature indicating knocking” in the sensor signal is a feature that the sensor signal (filtered sensor signal in each of the above embodiments) is equal to or greater than the knocking determination value Nth. May be detected. In that case, in S150 of FIG. 3 or FIG. 7, each time when each of the filtered sensor signals A and B becomes the knocking determination value Nth or more is detected as each of the characteristic times tA and tB.

[Other embodiment 2]
For example, in the first embodiment, three or more knocking sensors may be provided for each cylinder #n of the engine 2.

In that case, in S120 of FIG. 3, it is determined whether or not the occurrence of knocking is indicated for each sensor signal from all the sensors of the cylinder #n.
If the determination in S130 of FIG. 3 is YES, for example, the above-described time difference Dt is calculated for each of the two sensor signals, and each of the time differences Dt must be within a predetermined range. For example, the process of S190 may be performed.

  Further, for example, even if the number of sensors is three or more, the above-described time difference Dt is calculated for only any two of the sensor signals, and if the time difference Dt is not within a predetermined range, the process of S190 May be performed.

  On the other hand, even when two sensors are provided for each cylinder #n as shown in FIG. 1, the same processing as when three or more sensors are provided for each cylinder #n can be performed. That is, the knocking determination for each cylinder may be performed using sensors for other cylinders. For example, when knocking determination is performed for cylinder # 1, not only sensor signals from sensors 3A-1 and 3A-2 but also sensor signals from sensors 3A-2 and 3B-2 for cylinder # 2 are used. It is also possible.

[Other embodiment 3]
For example, the plurality of knocking sensors are not limited to being arranged on the same plane with respect to the engine 2, and may be arranged three-dimensionally. For example, one of the three sensors may be provided on the upper surface of the engine 2, the other one on the lower surface of the engine 2, and the remaining one on the side surface of the engine 2.

[Other embodiment 4]
For example, in the first and second embodiments, a microphone (sound sensor) may be used as the detection means instead of the sensors 3A-1, 3B-1 to 3A-4, 3B-4, 3A, 3B. . If the microphone is used, the vibration of the engine 2 is detected through the air. Therefore, the time difference Dt can be correctly detected regardless of the individual difference or the structure difference of the engine 2, and thus The knocking determination accuracy can be improved.

[Other embodiment 5]
For example, the configuration of the ECU 1 of the first and second embodiments can be applied to a general knocking test apparatus.

[Other embodiment 6]
For example, in the first embodiment, the determination flag may be set to “1” before proceeding to S200 after determining YES in S180 of FIG. In that case, the processing of S140 and S190 can be deleted. Such a modification can be similarly applied to the second embodiment.

[Other embodiment 7]
For example, in the first and second embodiments, a resonance type knocking sensor may be used as the knocking sensor. In general, when a resonance type knocking sensor detects a vibration of a predetermined knocking frequency at a certain level or higher, the output voltage increases. For this reason, when the resonance type knocking sensor is used, the knocking determination process of FIG. 3 or FIG. 7 is not performed on the filtered sensor signal but on the sensor signal (corresponding to the detection signal) from the resonance type knocking sensor. What is necessary is just to be implemented with respect to it. In that case, the filters 9A and 9B in FIG. 1 or 6 can be deleted, or a low-pass filter as a noise filter can be used instead of the filters 9A and 9B. In that case, the processing of S120 and S150 in FIG. 3 or FIG. 7 can also be implemented by a hardware circuit that receives sensor signals.

[Other embodiment 8]
As the determination processing in S120 in FIG. 3 or 7 (processing for determining whether or not the sensor signal indicates knocking), other known processing for knocking determination may be used.

As mentioned above, although embodiment of this invention was described, this invention can take a various form, without being limited to the said embodiment. The above-mentioned numerical values are also examples, and other values may be used.
For example, the other embodiments 1 to 8 may be applied in combination. In addition, the functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified by the wording described in the claims are embodiments of the present invention. In addition to the ECU described above, the present invention is realized in various forms such as a system including the ECU as a constituent element, a program for causing a computer to function as the ECU, a medium storing the program, and a knocking detection method. You can also.

  DESCRIPTION OF SYMBOLS 1,31 ... ECU (electronic control apparatus), 2 ... Engine (internal combustion engine), 3A-1, 3B-1 to 3A-4, 3B-4, 3A, 3B ... Knocking sensor

Claims (6)

A plurality of detection means (3A-1, 3B-1 to 3A-4, 3B-4) which are arranged at different positions with respect to the internal combustion engine (2) and output detection signals corresponding to the vibration of the internal combustion engine. , 3A, 3B), the knocking detection device (1, 31) to which the detection signal is input,
Knocking determination means (S110 to S200) for determining whether knocking has occurred in the internal combustion engine based on the plurality of detection signals from the detection means;
The knocking determination means includes
For each of the plurality of detection signals, first determination means (S120) for determining whether the detection signal indicates occurrence of knocking;
If it is determined by the first determination means that all of the plurality of detection signals indicate the occurrence of knocking (S130: YES), it is determined that the first determination means indicates the occurrence of knocking. For at least two of the plurality of detected signals, it is determined whether or not a time difference in time at which a predetermined feature indicating knocking appears is within a predetermined range, and the time difference is within the predetermined range. Second determination means (S140 to S160, S180 to S200) for determining that knocking has occurred in the internal combustion engine,
A knocking detection device characterized by the above. The knocking detection device according to claim 1,
A plurality of filter means (9A, 9B) for extracting a knocking frequency component from each detection signal output from each detection means,
The first determination unit and the second determination unit operate using the detection signals output from the plurality of filter units as processing targets;
A knocking detection device characterized by the above. In the knocking detection device according to claim 1 or 2,
The predetermined characteristic is a characteristic that the detection signal has a maximum value;
A knocking detection device characterized by the above. In the knocking detection device according to any one of claims 1 to 3,
Two detection means (3A, 3B) are provided for the internal combustion engine,
The knocking determination means is configured to determine whether knocking has occurred for each of the plurality of cylinders of the internal combustion engine,
Further, the knocking determination means uses the predetermined range used by the second determination means (S140 to S160, S182 to S200) for determining the time difference for each cylinder to be determined whether knocking has occurred. Comprising setting means (S175) for switching and setting;
A knocking detection device characterized by the above. In the knocking detection device according to any one of claims 1 to 3,
The plurality of detection means (3A-1, 3B-1 to 3A-4, 3B-4) are provided for each of the plurality of cylinders of the internal combustion engine,
The knocking determination means determines, for each cylinder, whether knocking has occurred or not based on detection signals from the plurality of detection means corresponding to the cylinder;
A knocking detection device characterized by the above. The knocking detection device according to any one of claims 1 to 5,
The detection means is a microphone;
A knocking detection device characterized by the above.

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