JP6424718B2 - Knocking detection device - Google Patents

Description

  The present invention relates to an engine knocking detection device.

  There is a knock detection device that converts engine vibration into an electric 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 (eg, patent document 1). Knocking stands for knocking.

Unexamined-Japanese-Patent No. 5-340292

  In the conventional knock detection device, for example, when a vibration similar to the characteristics of knocking occurs in a portion other than the cylinder in the engine, there is a high possibility that the knocking is erroneously determined to be present (that is, knocking occurred). .

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

  Detection signals from a plurality of detection means are input to the knocking detection device of the first invention. Each of the plurality of detection means is disposed at a different position with respect to the internal combustion engine, and outputs a detection signal according to the vibration of the internal combustion engine.

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

The first determination means determines, for each of the plurality of detection signals, whether or not the detection signal indicates the occurrence of knocking.
The second determination means operates when the first determination means determines that all of the plurality of detection signals indicate the occurrence of knocking. The second determination means determines a time difference between times when predetermined characteristics indicating knocking appear for at least two of the plurality of detection signals determined to indicate 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 the occurrence of knocking in the cylinder of the internal combustion engine to the appearance of a predetermined characteristic indicating knocking in each of the detection signals from each of the detection means is determined by the distance between the occurrence position of knocking and each of the detection means. Therefore, when knocking occurs, it is considered that the time difference between the times when the above-mentioned predetermined features appear in each detection signal is within the predetermined range. Conversely, even if it is determined by the first determination means that all of the plurality of detection signals indicate the occurrence of knocking, knocking occurs if the above time difference for at least two detection signals is not within the predetermined range. It can be judged that it is not. In that case, for example, it is considered that vibration similar to the characteristic of knocking occurred in a portion other than the cylinder in the engine.

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

  In addition, the code | symbol in the parentheses described in the claim shows 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 composition of the electronic control unit (ECU) of a 1st embodiment. It is explanatory drawing of a knocking determination period. It is a flowchart showing the knocking determination processing of 1st Embodiment. It is explanatory drawing explaining the case where it determines with knocking presence as an effect | action of the knocking determination processing of 1st Embodiment. It is explanatory drawing explaining the case where it determines with no knocking as an effect | action of the knocking determination process of 1st Embodiment. It is a block diagram showing the structure of the electronic control unit (ECU) of 2nd Embodiment. It is a flowchart showing the knocking determination process of 2nd Embodiment.

  Hereinafter, an electronic control unit (hereinafter referred to as an ECU) according to an embodiment to which the present invention is applied will be described. The ECU according to the present embodiment is an ECU that controls an engine (internal combustion engine) of a vehicle, but in the following, matters relating to detection of knocking will be described. The ECU is an abbreviation of "Electronic Control Unit".

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

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

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

  In the sensor code (3A-1, 3B-1 to 3A-4, 3B-4), "3A-n", where n (n is any one of 1 to 4) following "-" , “3B−n” means that the sensor attached with the code corresponds to the cylinder #n. Further, in the following description, when the cylinders # 1 to # 4 are not particularly distinguished, "#n" is used as the code of the cylinder, and "#n" is used as the code of the 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 of the cylinders # 1 to # 4 sandwich each of the cylinders # 1 to # 4 and each cylinder # 1. It is provided at symmetrical positions with respect to the central axis of ~ 4. The positional relationship of the sensors 3A-1, 3B-1 to 3A-4, and 3B-4 with respect to the cylinders # 1 to # 4 is the same for all the cylinders # 1 to # 4. Such arrangement of sensors is, of course, an example.

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

  Sensor signals from one of the sensors 3A-1, 3A-2, 3A-3, 3A-4 for each of the cylinders # 1 through # 4 are input to the multiplexer 5A. Then, in response to a command from the microcomputer 11, the multiplexer 5A selects one of the sensor signals from the sensors 3A-1 to 3A-4 and outputs the selected one to the amplifier 7A.

  Sensor signals from the other sensors 3B-1, 3B-2, 3B-3, 3B-4 for the cylinders # 1 through # 4 are input to the multiplexer 5B. Then, in response to a command from the microcomputer 11, the multiplexer 5B selects one of the sensor signals from the sensors 3B-1 to 3B-4 and outputs the selected one 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 (an oscillation frequency specific to knocking, for example, 5 to 15 kHz) from a sensor signal input from the amplifier 7A. Then, 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 the 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 filters of analog circuits, 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 for storing calculation results of the CPU 13, an A / D converter (ADC) 19, and a register 21. .

  Further, an injector 23 for injecting fuel to each of the cylinders # 1 to # 4 and an igniter 25 for igniting each of the cylinders # 1 to # 4 are connected to the ECU 1. Although one injector 23 and one igniter 25 are shown in FIG. 1, they are actually provided for the respective cylinders # 1 to # 4.

  In the ECU 1, one of the sensor signals from the sensors 3A-1 to 3A-4 is input to the filter 9A through the multiplexer 5A and the amplifier 7A, and the sensor signal passing through the filter 9A is input to the microcomputer 11 Be done. Similarly, any one 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 Ru. 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 of each sensor signal passed through each of the filters 9A and 9B by the A / D converter 19, and using the A / D conversion result, is knocking occurring in the engine 2? It is determined whether or not (ie, presence or absence of knocking). 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. And the thing of the A / D conversion result of a sensor signal after a filter is also called a sensor value after a filter. The filtered sensor value will indicate the magnitude of knocking.

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

  The microcomputer 11 sets a period in 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 it is determined whether or not knocking has occurred. For example, as shown by the hatched portion in FIG. 2, for each of the cylinders # 1 to # 4, a period for a predetermined crank angle from the ignition timing by the igniter 25 is set as the knocking determination period Kp. The period for 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 an ignition pulse to the igniter 25, and the fall timing from high (ON) to low (OFF) of the ignition pulse is the ignition timing. . And these things are the same also about FIG. 4, FIG. 5 mentioned later. Further, for example, the ignition order of the cylinders # 1 to # 4 is "# 1 → # 2 → # 4 → # 3". Of the three hatched portions in FIG. 2, for example, the hatched portion on the left is the knocking determination period Kp for cylinder # 1, the hatched portion in the center is the knocking determination period Kp for cylinder # 2, and the right hatched portion. The hatched portion is the knocking determination period Kp of the cylinder # 4.

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

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

Then, the microcomputer 11 executes the knocking determination process of FIG. 3 each time the knocking determination period Kp of each of the cylinders # 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 ends will be described. That is, it is assumed that the presence or absence of knocking is determined for the cylinder #n. Further, 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 passing through the filter 9A is referred to as a post-filtering sensor signal A, and the post-filtering sensor signal The result of A / D conversion 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-filtering sensor signal B. The result of A / D conversion is referred to as a post-filter sensor value B.

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

  Then, the microcomputer 11 determines whether 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 in the next S120. . For example, as to the sensor signal A, the microcomputer 11 determines whether there is 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 It is determined whether or not. Then, if there is a filtered sensor value A that is equal to or greater than the knocking determination value Nth, it is determined that the sensor signal A indicates the occurrence of knocking. Similarly, as to the sensor signal B, the microcomputer 11 determines whether or not the after-filtering sensor value B is equal to or higher than the knocking determination value Nth among the after-filtering sensor values B for the knocking determination period Kp stored in the RAM 17. judge. Then, if there is a filtered sensor value B that is equal to or greater than the knocking determination value Nth, it is determined that the sensor signal B indicates the occurrence of knocking.

  The microcomputer 11 determines in the next S130 whether or not all the determination results for each of the sensor signals A and B in S120 are "knocking present". That all the determination results for each of the sensor signals A and B are "knocking" means that it is determined in S120 that all of the sensor signals A and B indicate the occurrence of knocking.

  Then, when the microcomputer 11 makes a negative determination (determination is NO) in S130 (that is, even when one of the sensor signals A and B does not indicate occurrence of knocking), the knocking determination process is performed as it is. Finish.

  When the microcomputer 11 makes an affirmative determination (YES) at S130 (that is, when all the sensor signals A and B indicate the occurrence of knocking), the microcomputer 11 proceeds to S140 and determines that the determination flag is “ Set to “1”, which indicates “with knocking”. However, the setting of the determination flag in S140 is the setting based on the temporary determination (that is, the temporary setting).

  Then, at the next S150, the microcomputer 11 detects the time at which a predetermined feature indicating knocking appears (hereinafter referred to as feature time) for each sensor signal A, 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 have become maximum values (in other words, peak values). Therefore, in S150, the microcomputer 11 detects, for each of the post-filter sensor signals A and B, the time at which it reaches the maximum value as the characteristic time.

  Specifically, the microcomputer 11 detects the maximum value from the after-filter sensor value A for the knocking determination period Kp stored in the RAM 17, and performs A / D conversion of the after-filter sensor value A, which is the maximum value. The time when the above is performed is stored as the characteristic time tA for the sensor signal A. Similarly, the microcomputer 11 detects the maximum value from the after-filter sensor value B for the knocking determination period Kp stored in the RAM 17, and performs A / D conversion of the after-filter sensor value B which is the maximum value. The stored time is stored as the characteristic time tB for the sensor signal B.

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

In S170, the microcomputer 11 sets a knocking presence / absence determination time R used in the next S180. The knocking presence determination time R will be described later.
At S180, the microcomputer 11 determines whether the time difference Dt calculated at S160 is equal to or less than the knocking determination time R. In addition, since the minimum value of the time difference Dt is 0, the determination in S180 is to determine whether the time difference Dt is in the range of “0 to R”.

  When the microcomputer 11 determines in S180 that the time difference Dt is equal to or less than the knocking determination time R, it determines that knocking has actually occurred for the cylinder #n, and changes the setting of the determination flag. Instead, the process directly proceeds to S200.

  When the microcomputer 11 determines in S180 that the time difference Dt is not less than the knocking determination time R, that is, when the time difference Dt is not within the range of "0 to R", it is assumed that knocking has not occurred. Judge and proceed to S190. Then, in S190, the microcomputer 11 rewrites the determination flag from "1" to "0", and then proceeds to S200.

  The microcomputer 11 determines in S200 whether the determination flag is "1". If the determination flag is not "1", the knocking determination process is ended as it is, but the determination flag is "1". For example, it progresses to S210. Then, in step S210, the microcomputer 11 performs, for example, processing of retarding the ignition timing for the engine 2 as processing for canceling the knocking, and then ends the knocking determination processing.

Here, the knocking presence / absence determination time R used for the determination in S180 will be described.
The time from the occurrence of knocking in cylinder #n to the appearance of a predetermined feature indicating knocking in each of sensor signals A and B (in the present embodiment, the time until filtered sensor signals A and B reach a maximum value) The time t) is determined by the distance between the occurrence position of knocking and each sensor 3A-n, 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 each of 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 the occurrence of knocking, knocking does not occur if the time difference Dt calculated in S160 is not within the predetermined range. It can be judged.

  Further, in the present embodiment, since the distances from the central 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, knocking presence / absence determination time R is set to the maximum value of time difference Dt when knocking occurs in 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 determination time R predetermined by theoretical calculation or experiment, and the microcomputer 11 performs a process of reading the knocking presence 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, and 3B-4 with respect to the cylinders # 1 to # 4 is the same for all the cylinders # 1 to # 4. The knocking presence / absence determination time R also uses the same value for all the cylinders # 1 to # 4. On the other hand, for example, when the transmission speed of vibration from the sensors 3A-1, 3B-1 to 3A-4, and 3B-4 is different for each of the cylinders # 1 to # 4, or the sensors 3A-1, 3B-1 to 3A If the positional relationship between -4 and 3B-4 is different, in step 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 using FIG. 4 and FIG. 4 and 5, the waveform of the stage of "sensor A" represents the filtered sensor signal A, and the waveform of the stage of "sensor B" represents the filtered sensor signal B.

  When knocking occurs in the cylinder #n, as shown in FIG. 4, both the after-filtering sensor signal A and the after-filtering sensor signal B have knocking determination values in the knocking determination period Kp of the cylinder #n. Nth or more. For this reason, 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, and YES is determined in S130, and the determination flag is “S140”. It is set to 1 ". Furthermore, 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 as YES in S180, and the determination flag remains “1”. That is, it is finally determined that knocking has occurred for the cylinder #n. As a result, in order to eliminate knocking, processing is performed to retard the ignition timing (S210).

  On the other hand, in the knocking determination period Kp of the cylinder #n, for example, it is assumed that a vibration similar to the characteristic of knocking occurs outside the cylinder #n. Then, as shown in FIG. 5, it is assumed that both the after-filtering sensor signal A and the after-filtering sensor signal B in the knocking determination period Kp become 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, and YES is determined in S130, and the determination flag is “1” in S140. Set to '.

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

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

  Further, in the ECU 1, from the sensor signals outputted from the sensors 3A-1, 3B-1 to 3A-4, and 3B-4, frequency components of knocking are extracted by the filters 9A and 9B, and in the knocking determination process of FIG. , And the filtered sensor signal that has passed through the filters 9A and 9B is to be processed. Therefore, it is possible to process only the signal of the frequency band generated by knocking out of the signals of various frequencies. Therefore, unnecessary calculations can be eliminated, and the knocking determination time can be shortened.

  Further, the ECU 1 detects the feature that the sensor signal (in the present embodiment, the post-filtering sensor signal) reaches 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.

  Further, in the present embodiment, a plurality of (two in this example) sensors 3A-n and 3B-n are provided for each cylinder #n of the engine 2. Then, in the knocking determination process, it is determined whether or not knocking has occurred for each cylinder #n based on sensor signals A and B from the sensors 3A-n and 3B-n corresponding to the cylinder #n. Therefore, the distance between the generation source of knocking and the sensor can be reduced, and the presence or absence of knocking can be determined with higher accuracy based on a sensor signal having a good S / N ratio related to knocking. Moreover, there is an advantage of being less susceptible to the influence between cylinders.

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

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

  Also in the second embodiment, 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 multiplexers 5A and 5B are not provided in the ECU 31 of the second embodiment. The sensor signal A from the sensor 3A is input to the microcomputer 11 through the amplifier 7A and the filter 9A, and the sensor signal B from the sensor 3B is input to the microcomputer 11 through the amplifier 7B and the filter 9B.

  For this reason, the microcomputer 11 does not implement selective switching control on the multiplexers 5A and 5B. Then, in the knocking determination period Kp of each of the cylinders # 1 to # 4, the microcomputer 11 performs A / D conversion for each of the after-filtering sensor signals A and B output from the filters 9A and 9B at regular intervals. While being carried out, after-filtering sensor values A and B which are A / D conversion results for every fixed time are stored in RAM17 one by one.

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

  In S120, S130, S150, and S160 in the knocking determination process of FIG. 7, the sensor signals A from the sensors 3A and 3B, even when any knocking determination period Kp of the cylinders # 1 to # 4 ends. The same processing as that of the first embodiment is performed for B.

The microcomputer 11 proceeds to S175 after S160 in the knocking determination process of FIG. 7.
Then, in S175, the microcomputer 11 sets values according to the cylinder for which knocking determination is to be made, as two knocking presence / absence determination times R1 and R2 used for determination in later S188.

  The cylinder subject to knocking determination is a cylinder among cylinders # 1 to # 4 for which the presence or absence of knocking is to be determined, and is a cylinder for which the present knocking determination period Kp has ended. R1 of knocking presence / absence determination times R1 and R2 is the minimum value of time difference Dt when knocking occurs in the cylinder subject to knocking determination, and R2 of knocking presence / absence determination times R1 and R2 is a knocking determination target The maximum value of the time difference Dt when knocking occurs in the cylinder of The time difference Dt is the time difference Dt calculated in S160.

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

  The microcomputer 11 proceeds to S182 after S175 and determines whether the cylinder subject to knocking determination is any one of the cylinders # 1 and # 2, and if a positive determination is made (YES is determined), the process proceeds to S184. Go to

  Then, in S184, the microcomputer 11 compares the feature times tA and tB of the sensor signals A and B detected in S150, and determines whether "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) at S182, that is, if the cylinder subject to knocking determination is any of the cylinders # 3 and # 4, the process proceeds to S186.
Then, in S186, the microcomputer 11 compares the feature times tA and tB of the sensor signals A and B detected in S150, and determines whether "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 the time difference Dt calculated in S160 is within the range from R1 to R2 set in S175.
Then, when the microcomputer 11 determines that the time difference Dt is within the range of “R1 to R2” at S188, it determines that knocking has actually occurred for the cylinder subject to knocking determination, and the determination flag Without changing the setting, the process directly proceeds to the above-described S200.

  Further, when the microcomputer 11 determines in S188 that the time difference Dt is not within the range of "R1 to R2", it determines that knocking has not occurred, proceeds to S190, and determines the flag in S190. Is rewritten to "0", and then the process proceeds to S200.

  On the other hand, when the microcomputer 11 determines that "tA <tB" is not satisfied at S184 or when it determines that "tA> tB" is not satisfied at S186, the process proceeds to S190, and the determination flag is set at S190. After rewriting to “0”, the process proceeds to S200.

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

  Therefore, the microcomputer 11 is configured to switch and set the knocking on / off determination time periods R1 and R2 used for the determination of the time difference Dt in S188 for each cylinder to be subjected to knocking determination in 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 two sensors 3A and 3B in the engine 2.
Further, as viewed from the cylinders # 1 and # 2, the position of the sensor 3A is closer than the position of the sensor 3B, and as viewed from the cylinders # 3 and # 4, the position of the sensor 3B is closer than the position of the sensor 3A.

  Therefore, when knocking determination is performed on any of the cylinders # 1 and # 2, if the knocking occurs in the cylinder, the characteristic time tA for the sensor signal A is the sensor signal B. It should be earlier than the feature time tB.

  When knocking determination is performed on any of the cylinders # 3 and # 4, if the knocking occurs in the cylinder subject to knocking determination, the characteristic time tA for the sensor signal A is the sensor signal B. It should be later than the feature time tB.

  Therefore, when any 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 one of the cylinders # 3 and # 4 is the knocking determination target (S182: NO), the microcomputer 11 determines whether or not "tA> tB" at 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 as to which of the feature times tA and tB comes first is also detected to prevent an erroneous determination of the presence of knocking. In other words, the condition that which of the characteristic times tA and tB comes first is added to the condition for determining that knocking is present. Further, in the second embodiment, it is determined whether the time difference with the plus and minus sign “tA−tB” is within the predetermined range in total of S182 to S186 and S188. Therefore, it is possible to more accurately determine the presence or absence of knocking.

[Other Embodiment 1]
For example, in the first and second embodiments, as the “predetermined feature indicating knocking” in the sensor signal, the sensor signal (in the above embodiments, the post-filtering sensor signal) has reached the knocking determination value Nth or more. May be detected. In that case, in S150 of FIG. 3 or FIG. 7, each time when each of the after-filtering sensor signals A and B becomes equal to or higher than the knocking determination value Nth 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 the occurrence of knocking is indicated for each sensor signal from all the sensors of cylinder #n.
And when it determines with YES by S130 of FIG. 3, the above-mentioned time difference Dt is calculated about each two of each sensor signal, for example, and each of the time difference Dt should be within the predetermined range defined beforehand. For example, the process of S190 may be performed.

  For example, even if the number of sensors is three or more, the above-mentioned time difference Dt is calculated for only any two of the sensor signals, and if the time difference Dt is not within the predetermined range, the process of S190 You may do it.

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

Another Embodiment 3
For example, the plurality of knocking sensors may be three-dimensionally arranged with respect to the engine 2 without being arranged on the same plane. For example, one of the three sensors may be provided on the upper surface of the engine 2, the other may be provided on the lower surface of the engine 2, and the remaining one may be provided on the side 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 in place of the sensors 3A-1, 3B-1 to 3A-4, 3B-4, 3A, 3B. . By using the microphone, the vibration of the engine 2 is detected through the air, so that the above-mentioned time difference Dt can be correctly detected regardless of the individual difference or the structure difference of the engine 2, and thus, The determination accuracy of knocking can be improved.

Another Embodiment 5
For example, the configuration of the ECU 1 of the first and second embodiments can be applied to a general knocking test device.

Another Embodiment 6
For example, in the first embodiment, the determination flag may be set to “1” before the process proceeds to S200 after the determination in S180 of FIG. 3 is YES. In that case, the processes of S140 and S190 can be deleted. Such a modification can be applied to the second embodiment as well.

Another Embodiment 7
For example, in the first and second embodiments, a resonant knocking sensor may be used as the knocking sensor. Generally, in the resonant knocking sensor, the output voltage increases when the vibration of a predetermined knocking frequency is detected at a predetermined level or more. Therefore, when a resonant knocking sensor is used, the knocking determination process of FIG. 3 or 7 is not for the post-filter sensor signal but for a sensor signal (corresponding to a detection signal) from the resonant knocking sensor. It is good if it is made to be implemented. In that case, the filters 9A and 9B of FIG. 1 or FIG. 6 can be eliminated or, instead of the filters 9A and 9B, a low pass filter as a noise filter can be used. In that case, the processing of S120 or S150 in FIG. 3 or 7 may be configured to be implemented by a hardware circuit that receives a sensor signal.

Another Embodiment 8
The determination process of S120 in FIG. 3 or 7 (a process of determining whether the sensor signal indicates the presence of knocking) may be another known process for determining knocking.

As mentioned above, although embodiment of this invention was described, this invention can take various forms, without being limited to the said embodiment. Moreover, the above-mentioned numerical value is also an example and may be another value.
For example, the other embodiments 1 to 8 may be applied in combination. Also, the function of one component in the above embodiment may be distributed as a plurality of components, or the function 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. In addition, part of the configuration of the above embodiment may be omitted. In addition, at least a part of the configuration of the above-described embodiment may be added to or replaced with the configuration of the other above-described embodiment. In addition, all the aspects contained in the technical thought specified by the words described in the claim are embodiments of the present invention. In addition to the above-described ECU, the present invention can be realized in various forms such as a system having the ECU as a component, a program for causing a computer to function as the ECU, a medium storing the program, a knocking detection method, and the like. You can also.

  1, 31 ... ECU (electronic control unit), 2 ... engine (internal combustion engine), 3A-1, 3B-1 to 3A-4, 3B-4, 3A, 3B ... knocking sensor

Claims (4)

Knocking detection in which the detection signals are input from a plurality of detection means ( 3A, 3B) which are respectively disposed at different positions with respect to the internal combustion engine (2) and output detection signals according to the vibration of the internal combustion engine The device ( 31),
Knocking determination means (S110 to S200) for determining whether or not knocking has occurred in the internal combustion engine based on a plurality of the detection signals from the detection means;
The knocking determination means
First determining means (S120) for determining whether or not the detection signal indicates the occurrence of knocking for each of the plurality of detection signals;
When it is determined that all of the plurality of detection signals indicate the occurrence of knocking by the first determination means (S130: YES), it is determined that the occurrence of knocking is indicated by the first determination means For at least two of the plurality of detected signals, it is determined whether or not a time difference between times when a predetermined feature indicating knocking appears appears within a predetermined range, provided that the time difference is within the predetermined range. said second determining means for determining that knocking has occurred in the internal combustion engine (S140~S160, S18 2 ~S200) provided with, a,
Two of the detection means are provided for the internal combustion engine,
The knocking determination means is configured to determine whether or not knocking has occurred for each of a plurality of cylinders of the internal combustion engine.
Further, the knocking determination means sets and switches the predetermined range used by the second determination means for determining the time difference for each cylinder for which it is determined whether knocking has occurred or not (S175). To provide
Knocking detection device characterized by. In the knocking detection device according to claim 1,
A plurality of filter means (9A, 9B) for extracting a knocking frequency component from the detection signals output from the detection means;
The first determination unit and the second determination unit operate with the detection signals output from the plurality of filter units as targets of processing.
Knocking detection device characterized by. In the knocking detection device according to claim 1 or 2,
The predetermined feature is that the detection signal has reached a maximum value,
Knocking detection device characterized by. The knocking detection device according to any one of claims 1 to 3.
The detection means is a microphone,
Knocking detection device characterized by.

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