JP2008240627A - Knocking determining device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a knocking determining device capable of determining whether or not a signal component except for knocking is superimposed on a detecting signal in actual operation. <P>SOLUTION: This knocking determining device 1 determines the existence of the knocking occurrence by processing the detecting signal from a vibration sensor 2 arranged in an engine, and is constituted for determining knocking by removing a vibration component except for the knocking by determining that the vibration component except for the knocking is superimposed, when an RMS value of the largest number area is larger than a predetermined reference value and its distribution width is within a predetermined range. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a knock determination device that processes a detection signal from a knock detection sensor such as a vibration sensor provided in an engine to determine whether or not knocking has occurred.

2. Description of the Related Art Conventionally, an engine knocking detection device is configured to subtract a predetermined background noise component stored in advance according to an operating state in order to remove the influence of mechanical vibration noise. 0014, 0019 and FIG.
JP-A-6-272607

  However, the conventional configuration is a configuration in which a predetermined background noise component corresponding to the driving state is uniformly subtracted from the detection signal, but there are cases where a signal component other than knocking is superimposed on the detection signal and not. First, it is necessary to determine whether or not a signal component other than knocking is superimposed on the detection signal.

  In addition, the conventional configuration needs to measure background noise in advance, but this is difficult to measure because it must be measured without knocking. Since the background noise changes with time, in order to prevent a decrease in determination accuracy, it must be measured at appropriate intervals even if it is measured once.

  Accordingly, an object of the present invention is to provide a knock determination device that enables determination during operation whether or not a signal component other than knocking is superimposed on a detection signal during actual operation.

  It is another object of the present invention to provide a knock determination device that removes signal components other than knocking when it is determined that signal components other than knocking are superimposed.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, according to the first aspect of the present invention, in the knocking determination device that determines whether knocking has occurred by processing a detection signal from a knocking detection sensor such as a vibration sensor provided in the engine, the RMS of the detection signal in a predetermined combustion cycle is determined. Among the distribution of values, when the RMS value of the most numerous region is larger than a predetermined reference value and the distribution width is within a predetermined range, it is determined that a vibration component other than knocking is superimposed and other than the knocking The vibration component is removed and knocking determination is performed.

  According to a second aspect of the present invention, in the knocking determination device that determines whether knocking has occurred by processing a detection signal from a vibration sensor provided in the engine, a predetermined threshold value is set in the RMS value of the detection signal in a predetermined combustion cycle. When the distribution of the integrated value of the RMS value exceeding the average value in the predetermined combustion cycle is within a predetermined range, it is determined that vibration components other than knocking are superimposed, and vibration components other than the knocking are removed. Knocking determination.

  According to claim 3, in the engine knock determination device according to claim 2, in calculating whether the distribution of the RMS value exceeding the predetermined threshold with respect to the average value of the integrated value is within the predetermined range, the average value and the appropriate value are determined. Comparing the magnitude relationship with the upper limit value, if the upper limit value is exceeded, the difference between the average value and the appropriate upper limit value is multiplied by a predetermined constant to calculate the estimated lower limit value of the integrated value, and the estimated lower limit value Is compared with the integrated value and the magnitude relation is less than or equal to the estimated lower limit value, it is determined that vibration components other than knocking are superimposed, and knocking determination is performed by removing vibration components other than the knocking. .

  According to a fourth aspect of the present invention, in the engine knocking determination device according to the third aspect, in removing the vibration component other than the knocking, a sum of a value obtained by multiplying the integrated value by the inverse of the predetermined constant and a predetermined adjustment value is used. A value obtained by subtracting the average value is used as a removal value and removed from the RMS value of the detection signal to perform knocking determination.

  According to claim 5, in the engine knock determination device according to claim 4, in calculating whether or not the distribution of the integrated value of the RMS value exceeding a predetermined threshold value is within a predetermined range, the average value and an appropriate value are determined. Compares the magnitude relationship with the lower limit value, and if it falls below the appropriate lower limit value, the difference value between the appropriate lower limit value and the average value is used as a return value to add to the RMS value of the detection signal to perform knocking determination. is there.

  According to claim 6, in the engine knock determination device according to claim 4, when selecting the appropriate upper limit value for comparing the average value with the magnitude relationship, the appropriate upper limit value is properly used for the steady operation and the transient time. Is set to a value smaller than the appropriate upper limit value during steady operation.

  According to a seventh aspect of the present invention, in the knocking determination device according to the fourth aspect, the strength determination is performed using an integrated value equal to or greater than a predetermined threshold among the RMS values obtained by subtracting the removal value from the RMS value of the detection signal as a knocking strength determination value. When the value is equal to or greater than a predetermined limit value determined from the correlation with the knocking allowable limit, it is determined that knocking has occurred, and a function of retarding the ignition timing after the determination is added.

  As effects of the present invention, the following effects can be obtained.

  In the first aspect, only when signal components other than knocking are superimposed, knocking determination is performed by removing those signals, so that the determination accuracy is improved.

  In the second aspect, only when vibration components other than knocking are superimposed, knocking determination is performed by removing those vibration components, so that the determination accuracy is improved. Further, the storage capacity of the storage means can be saved as compared with the configuration in which the determination is made based on the distribution of all RMS values in the sampling period as in the first aspect.

  In the third aspect, only when vibration components other than knocking are superimposed, knocking determination is performed by removing those vibration components, so that the determination accuracy is improved. Further, the storage capacity of the storage means can be saved as compared with the configuration in which the determination is made based on the distribution of all RMS values in the sampling period as in the first aspect.

  According to the fourth aspect, only when vibration components other than knocking are superimposed, knocking determination is performed by removing those vibration components, so that the determination accuracy is improved. Further, the storage capacity of the storage means can be saved as compared with the configuration in which the determination is made based on the distribution of all RMS values in the sampling period as in the first aspect.

  According to the fifth aspect of the present invention, it is possible to restore the removal value to be removed from the RMS value, so that it is possible to cope with a decrease in vibration components other than knocking.

  According to the sixth aspect, the accuracy of knocking determination can be improved by reliably removing vibration components other than knocking at the time of transition where vibration components other than knocking such as mechanical vibration due to piston slap are highly likely to be superimposed.

  In claim 7, recurrence of knocking can be avoided.

  Next, embodiments of the invention will be described.

  FIG. 1 is a block diagram showing an overall configuration of a knock determination device according to an embodiment of the present invention, FIG. 2 is a diagram showing a distribution of RMS values of detection signals in a predetermined combustion cycle, and FIG. FIG. 4 is an explanatory diagram of a method for determining whether or not a vibration component other than knocking is superimposed on the RMS value of the detection signal of FIG. 4, FIG. 4 is a flowchart for removing vibration components other than knocking, and FIG. FIG.

  In a spark ignition engine such as a gas engine equipped with a knocking determination device 1 according to an embodiment of the present invention, a vibration sensor 2 for detecting engine vibration is provided at an arbitrary position such as a cylinder block or a cylinder head. The vibration sensor 2 is connected to control means (not shown) of the internal combustion engine, and as shown in FIG. 1, the detection signal is input to the knocking determination device 1 via the control means.

  In the knock determination device 1, the detection signal from the vibration sensor 2 is processed to determine whether or not knocking has occurred. The detection signal from the vibration sensor 2 input to the knocking determination device 1 is sent to the filter means 3 to first pass through the time gate 4 that passes only the vibration generated at a certain time, and then the noise component in a predetermined frequency range. It is passed through a frequency filter 5 that removes and passes only signals in a specific frequency range.

  In the filter means 3, first, a detection signal corresponding to the knocking occurrence timing of a predetermined cylinder is extracted by processing by the time gate 4 to be a first extraction signal. Next, a signal in a frequency range necessary for knocking determination is extracted from the first extraction signal by the bandpass processing of the frequency filter 5 to be a second extraction signal. Then, the second extracted signal after the band pass processing is output from the filter unit 3 and input to the calculation unit 6.

  In the calculation means 6, the RMS (Root Mean Square) value of the detection signal from the vibration sensor 2 that has passed through the filter means 3 is calculated. The RMS value is used to determine whether or not a vibration signal other than knocking that could not be removed by the filter means 3 is superimposed on the detection signal from the vibration sensor 2, that is, the second extraction signal, as will be described later. Then, an arithmetic process according to the determination result is performed.

  Subsequently, a knocking strength determination value is calculated from the RMS value after the arithmetic processing, and knocking determination is performed based on the knocking strength determination value. If it is determined that knocking has occurred in this knocking determination, various control signals for retarding the ignition timing or issuing an alarm are output. Thereby, the recurrence of knocking can be avoided.

  Below, the arithmetic processing in the calculating means 6 of the knock determination apparatus 1 will be described in detail in two embodiments.

  When the RMS value of the detection signal from the vibration sensor 2 is calculated, the calculation means 6 calculates the distribution of the RMS value of the detection signal in a predetermined combustion cycle. In the RMS value distribution, it is determined whether the RMS value in the most numerous region is larger than a predetermined reference value and the distribution width is within a predetermined range. It is determined whether or not vibration components other than knocking such as mechanical vibration due to piston slap are superimposed.

  As shown in FIG. 2 (a), the distribution of the RMS value at the time of knocking occurs when the vibration signal other than knocking is not superimposed on the detection signal from the vibration sensor 2 as a tendency in a predetermined combustion cycle. Are distributed over a wide range R1 to form a so-called normal distribution. On the other hand, when vibration components other than knocking are superimposed, as shown in FIG. 2B, the sampling number is distributed in a predetermined range R2 near a specific RMS value. Further, this specific RMS value is larger than the predetermined reference value.

  Therefore, in the distribution of measured RMS values, when the RMS value of the most numerous region is larger than the predetermined reference value and the distribution width is within the predetermined range R2, the detection signal from the vibration sensor 2 is not knocked. Is determined to be superposed, and processing for removing vibration components other than knocking is performed. Thereafter, a knocking strength determination value is calculated, and based on this, knocking determination is performed.

  As described above, in the knocking determination device 1, when the vibration sensor 2 is used as a knocking detection sensor and a detection signal from now on is processed to determine whether or not knocking has occurred, the detection signal from the vibration sensor 2 other than knocking is detected. As a configuration for determining whether or not vibration components are superimposed, knocking determination is performed by removing those vibration components only when vibration components other than knocking are superimposed, so that the determination accuracy can be improved. it can.

  When the RMS value of the detection signal from the vibration sensor 2 is calculated, the calculation means 6 calculates the integrated value of the RMS values exceeding a predetermined threshold among the RMS values of the detection signal in a predetermined combustion cycle. The distribution of the integrated value of the values with respect to the average value in the predetermined combustion cycle is calculated. Then, it is determined whether or not the distribution of the integrated value of the RMS value is within a predetermined range, so that a vibration component other than knocking such as mechanical vibration due to piston slap is superimposed on the detection signal from the vibration sensor 2. It is determined whether or not.

  When the knocking occurs, the distribution of the integrated value of the RMS value is, as shown in FIG. 3, as a tendency in a predetermined combustion cycle, when a vibration component other than knocking is not superimposed on the detection signal from the vibration sensor 2, That is, when only the vibration component of knocking is included, it falls within the range R3 with respect to the average value in a predetermined combustion cycle. On the other hand, when vibration components other than knocking are superimposed, they fall within the range R4 defined by the characteristic line L1 having the same gradient as described above.

  Therefore, when the distribution of the average value of the RMS values exceeding the predetermined threshold is within the predetermined range R4, it is determined that a vibration component other than knocking is superimposed on the detection signal from the vibration sensor 2, and knocking is performed. A removal value is calculated to remove vibration components other than. Then, after processing using this is performed as follows, a knocking strength determination value is calculated, and knocking determination is performed based on this.

  The removal of vibration components other than the knocking will be described with reference to the flowchart shown in FIG.

  As shown in FIG. 4, the removal of vibration components other than knocking is performed at each control cycle (step S1), and it is first determined whether or not the engine is in operation (step S1). S2). If it is determined that the engine is not operating, the removal value stored in the storage means 7 during the previous operation is cleared to 0 (step S3). During the next operation, if it is determined that vibration components other than knocking are superimposed as described above, a new removal value is calculated.

  On the other hand, when it is determined that the engine is in operation, it is determined whether or not a predetermined time has elapsed since the start of control, for example, when a predetermined load or more is applied (step S4). That is, it is determined whether the engine is in steady operation or in transition. This determination can also be made based on whether or not the engine is at a predetermined number of revolutions or more and whether or not the coolant temperature or the lubricating oil temperature is at or above a predetermined value.

  When it is determined that a predetermined time has elapsed from the start of control, the engine is determined to be in steady operation, and an appropriate upper limit value for steady state is selected as an appropriate upper limit value for comparing the average value with the magnitude relationship. (Step S5). Conversely, if it is determined that the predetermined time has not elapsed since the start of control, it is determined that the engine is in transition, and the appropriate upper limit for transition is selected as the appropriate upper limit (step S6).

  Here, the appropriate upper limit value for transition is set to a value smaller than the proper upper limit value for steady operation, and a vibration component other than knocking such as mechanical vibration due to piston slap is superimposed on the detection signal from the vibration sensor 2. In a transient state where there is a high possibility that the vibration component is likely to occur, the superposition of vibration components other than knocking can be reliably determined and removed. Thus, the accuracy of knocking determination can be improved by properly using the appropriate upper limit value during steady operation and during transition.

  Then, after the appropriate upper limit value of the average value of the RMS values is selected as either the appropriate upper limit value for steady operation or the appropriate upper limit value for transition, the above-mentioned appropriate upper limit value obtained from the selected appropriate upper limit value is used. A predetermined range R4 is determined. When the average value of the RMS values is within the predetermined range R4, it is determined that a vibration component other than knocking is superimposed on the detection signal from the vibration sensor 2 as described above, and is used to remove this. A removal value is calculated (step S7).

  That is, as shown in FIG. 5, in determining whether or not the average value of the RMS values exceeds a predetermined threshold value (appropriate upper limit value) and falls within the predetermined range R4, the average value of the RMS values and the appropriate upper limit value are small or large. The relationships are compared (step S71). For example, as shown in FIG. 3, when the distribution is made as indicated by the point N1, the average value of the RMS value is larger than the appropriate upper limit value in comparison with the average value of the RMS value and the appropriate upper limit value. The appropriate upper limit value is subtracted to obtain the difference value, and this difference value is multiplied by a predetermined constant (characteristic line gradient tan θ) to calculate the estimated lower limit value of the integrated value (step S72).

  Then, the estimated lower limit value of the integrated value is compared with the integrated value (Step S73). When the integrated value is less than or equal to the estimated lower limit value, it is determined that the average value of the RMS values is within the predetermined range R4. In the case of the point N1 shown in FIG. 3, since it is smaller than the estimated lower limit value of the integrated value, it is determined that it falls within the predetermined range R4. As a result, it is determined that a vibration component other than knocking is superimposed on the detection signal from the vibration sensor 2, and a removal value used to remove the vibration component other than knocking is calculated (step S74).

  In calculating the removal value, a characteristic line between an average value of RMS values and an integrated value when vibration components other than knocking do not overlap when knocking occurs is set as an adjustment line L2, and the removal value is calculated using the adjustment line L2. Calculated. That is, a value obtained by multiplying the integrated value by the reciprocal of the predetermined constant (tan θ) and the predetermined adjustment value of the average value are added together, and the total value is set as a corrected average value. The average value of the RMS values is subtracted from the corrected average value to calculate the removal value. Then, the removal value is added to the RMS value of the detection signal, and vibration components other than knocking are removed.

  In calculating the removal value after the first time, the removal value obtained by subtracting the average value from the correction average value is used as the correction removal value, and the correction removal value is added to the previous removal value to obtain the current removal value. Is calculated. As in the previous time, the removal value is added to the RMS value of the detection signal, and vibration components other than knocking are removed.

  On the other hand, when the average value is smaller than the appropriate upper limit value, the magnitude relationship between the average value and the appropriate lower limit value is subsequently compared (step S75). When the average value is lower than the appropriate lower limit value, the average value is subtracted from the appropriate lower limit value, and the difference value is set as the return value. This return value is added to the previous removal value, and the removal value is returned (decreased) (step S76). Thus, it is possible to cope with a decrease in vibration components other than knocking.

  After the removal of vibration components other than knocking, the RMS value obtained by subtracting the removal value from the RMS value of the detection signal from the vibration sensor 2 is accumulated, and the accumulated value is the knocking strength. Calculated as a judgment value. It is determined whether or not the knocking strength determination value is equal to or greater than a predetermined limit value determined from the correlation with the knocking allowable limit. If it is determined that the knocking strength determination value is equal to or greater than the predetermined limit value, it is determined that knocking has occurred.

  After it is determined that knocking has occurred in the knocking determination, a control signal is output by a function added to the knocking determination device 1, and control for retarding the ignition timing is performed. Thus, the recurrence of knocking can be avoided. When the knocking reoccurrence cannot be avoided by this knocking avoidance control, an alarm is notified and the engine is stopped.

  As described above, in the knocking determination device 1, when the detection signal from the vibration sensor 2 is processed to determine whether knocking occurs or not, whether or not a vibration component other than knocking is superimposed on the detection signal from the vibration sensor 2. As a configuration for performing such determination, only when vibration components other than knocking are superimposed, knocking determination is performed by removing those vibration components, so that determination accuracy can be improved. Further, the storage capacity of the storage unit 7 can be saved as compared with the configuration in which the determination is made based on the distribution of all RMS values in the sampling period (predetermined fuel cycle) as in the first embodiment.

1 is a block diagram showing the overall configuration of a knock determination device according to an embodiment of the present invention. The figure which shows distribution of the RMS value of the detection signal in a predetermined combustion cycle. Explanatory drawing of the method of determining whether the vibration components other than knocking are superimposed on the RMS value of the detection signal in a predetermined combustion cycle. The flowchart figure about the removal of vibration components other than knocking. The flowchart figure about calculation of a removal value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Knocking determination apparatus 2 Vibration sensor etc. (detection means)

Claims (7)

  In a knock determination device that processes a detection signal from a knock detection sensor provided in an engine and determines whether knock has occurred or not, among the RMS value distributions of detection signals in a predetermined combustion cycle, the RMS value of the most numerous region Is larger than a predetermined reference value and the distribution width is within a predetermined range, it is determined that signal components other than knocking are superimposed, and signal components other than the knocking are removed and knocking determination is performed. An engine knock determination device.   In a knocking determination device that processes a detection signal from a vibration sensor provided in an engine and determines whether knocking has occurred or not, an integrated value of RMS values exceeding a predetermined threshold among RMS values of detection signals in a predetermined combustion cycle When the distribution with respect to the average value in the predetermined combustion cycle is within a predetermined range, it is determined that vibration components other than knocking are superimposed, and knocking determination is performed by removing vibration components other than knocking. An engine knock determination device.   3. The engine knock determination device according to claim 2, wherein the magnitude relationship between the average value and the appropriate upper limit value is calculated in calculating whether the distribution of the RMS value exceeding the predetermined threshold value with respect to the average value is within a predetermined range. If the value exceeds the appropriate upper limit value, the difference between the average value and the appropriate upper limit value is multiplied by a predetermined constant to calculate the estimated lower limit value of the integrated value, and the estimated lower limit value, the integrated value, Engine knocking determination characterized in that, when the relation is compared and the estimated lower limit value or less, it is determined that vibration components other than knocking are superimposed, and knocking determination is performed by removing vibration components other than knocking apparatus.   4. The engine knock determination device according to claim 3, wherein a value obtained by subtracting an average value from a sum of a value obtained by multiplying an integrated value by the reciprocal of the predetermined constant and a predetermined adjustment value when removing vibration components other than the knocking. An engine knock determination device that performs knock determination by removing from the RMS value of the detection signal as a removal value.   5. The engine knock determination device according to claim 4, wherein the magnitude relationship between the average value and the appropriate lower limit value is calculated in calculating whether the distribution of the RMS value exceeding the predetermined threshold is within a predetermined range. When the value falls below the appropriate lower limit value, the difference value between the appropriate lower limit value and the average value is used as a return value and added to the RMS value of the detection signal to perform knocking determination. Judgment device.   5. The engine knock determination device according to claim 4, wherein in selecting an appropriate upper limit value for comparing the average value with the magnitude relationship, the appropriate upper limit value is properly used for the steady operation and the transient state, and the appropriate upper limit value in the transient state is set to be steady. A knocking determination device characterized in that the value is smaller than an appropriate upper limit during operation.   5. The knock determination device according to claim 4, wherein the RMS value obtained by subtracting the removal value from the RMS value of the detection signal is an integrated value equal to or greater than a predetermined threshold value as a knock strength determination value, and the strength determination value is determined as a knocking allowable limit. A knocking determination device characterized by adding a function of determining that knocking has occurred when a predetermined limit value determined from the correlation of the above is exceeded and retarding the ignition timing after the determination.

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