JP2004340104A - Correction method for output signal from vibration detection sensor, and correction coefficient calculation device for output signal from vibration detection sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a correction method for an output signal from a vibration detection sensor, and a correction coefficient calculation device for an output signal from a vibration detection sensor, applicable to an internal combustion engine of any kind. <P>SOLUTION: A noise level of a first internal combustion engine in a knocking generated driving state is detected using a microphone installed on a specific position with respect to the first internal combustion engine. An output signal corresponding to the noise level is recorded by a first knock sensor installed on the first internal combustion engine. A second internal combustion engine on which a second knock sensor is installed is driven in knocking generating conditions. The same microphone is installed on the same position with respect to the second internal combustion engine as that with respect to the first internal combustion engine. Its noise level and an output signal from the second knock sensor at the time are detected. The level of the output signal from the second knock sensor is corrected in such a way that the level of the output signal from the second knock sensor coincides with the level of the output signal of the first knock sensor to the same noise level. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for correcting an output signal of a vibration detection sensor, and a correction coefficient calculating device for an output signal of the vibration detection sensor.In particular, an output signal from a vibration detection sensor attached to a cylinder block of an internal combustion engine is used for an internal combustion engine. The present invention relates to a method of correcting the same value for the same knocking state and a device for calculating a correction coefficient of an output signal so as to obtain the same value.
[0002]
[Prior art]
In an internal combustion engine that uses gasoline as fuel, in the combustion stroke, the air-fuel mixture in the cylinder is ignited by the spark from the spark plug and burned, but the pressure in the cylinder becomes abnormally high during the flame propagation after ignition. In such a case, a knocking phenomenon occurs in which an unburned portion of the air-fuel mixture self-ignites before the propagation of the flame ends, causing an extreme pressure rise, and the internal combustion engine may be damaged.
[0003]
Therefore, a knock control system that is a control for suppressing such knocking and realizing an optimum torque and fuel efficiency has been conventionally proposed. In this knock control system, a vibration detection sensor called a knock sensor is attached to a cylinder block of the internal combustion engine to detect whether knocking occurs under the current operating conditions of the internal combustion engine. The presence or absence of knocking is determined by analyzing the vibration waveform of the internal combustion engine detected in step (1).
[0004]
Conventionally, when analyzing a signal detected by the knock sensor, a peak value of a vibration detection signal generated in each combustion cycle of the internal combustion engine has been used. That is, when the peak value is large, it is determined that knocking has occurred, and when the peak value is small, it is determined that background noise has occurred.
[0005]
However, according to the conventional method of detecting the occurrence of knocking based on the magnitude of the peak value of the vibration detection signal, when a large noise is generated from the internal combustion engine, a large peak value appears in the vibration detection signal, and this peak value is generated by the occurrence of knocking. May be erroneously determined. In other words, when the knocking strength is determined, the peak value of the signal from the knock sensor in each cycle is used and the magnitude is compared. However, since the knock sensor is a vibration detection sensor, the knock sensor is not used. In some cases, various vibrations (for example, valve seating noise and injector noise) generated from the internal combustion engine are detected, and electric noise or the like may be detected. If these noises are small, they can be ignored, but if these noises increase for some reason, the peak value of the vibration detection signal from the knock sensor increases, and the input noise is erroneously determined to be knocking. It will be done.
[0006]
On the other hand, in order to avoid the erroneous determination in the knocking determination based on the peak value as described above, it is possible to avoid the erroneous determination of the noise by using the effective value of the vibration detection signal from the knock sensor instead of the peak value. it can. Further, since the effective value of the signal from the knock sensor is very close to the knocking sound, the level of the sound actually audible can be determined from the knock sensor signal by determining the magnitude of the effective value.
[0007]
When the knock sensor is attached to the same internal combustion engine in the same state, the output signal from the knock sensor outputs the same signal with respect to the vibration of the cylinder block having the same magnitude. However, when they are attached to different internal combustion engines, the same signal is not necessarily output for vibrations of the same magnitude. This is due to a difference in the mounting position of the knock sensor to the internal combustion engine, the mounting method, and the like. Also, when different types of knock sensors are used, the outputs from the knock sensors are different.
[0008]
In order to solve such a problem, there has been proposed an apparatus which performs correction for unifying the input of the signal of the sensor for each model of the internal combustion engine. In this proposal, a correction coefficient for each model of an internal combustion engine is studied on a desk, and stored in a memory in a control device (control unit) for each model of the internal combustion engine, and this correction coefficient is used when calculating knock magnitude. The signal from the knock sensor is corrected (for example, see Patent Document 1).
[0009]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-195843 (page 8, left column, FIGS. 6 to 8)
[0010]
[Problems to be solved by the invention]
However, in the knocking detection device for an internal combustion engine described in Patent Literature 1, the correction coefficient for each model of the internal combustion engine is examined on a desk, so that a theoretical correction coefficient and a value that must be actually corrected are used. There is a possibility of deviation, and it is not possible to use the correct correction coefficient for the difference in the output signal of the knock sensor due to individual differences within the same model, and it is possible to respond to individual differences within the same model. There was a problem that it was not possible.
[0011]
Therefore, an object of the present invention is to provide a method for correcting an output signal of a vibration detection sensor that can be applied to all different internal combustion engines regardless of the model or the same model, and a correction coefficient calculation of an output signal of the vibration detection sensor. It is to provide a device.
[0012]
[Means for Solving the Problems]
A first mode of a method for correcting an output signal of a vibration detection sensor according to the present invention that achieves the above object is to operate a first internal combustion engine in a state where a microphone is installed at a specific position, and determine a noise level detected by the microphone. The output signal of the first vibration detection sensor attached to the first internal combustion engine is stored in association with the output signal of the first internal combustion engine. The operation is performed with the same microphone installed at the same position as the specific position, the noise level is detected, and the second vibration of the second internal combustion engine attached to the same position as that of the first internal combustion engine is detected. The output signal of the detection sensor is detected, and the second vibration is output so that the level of the output signal of the second vibration detection sensor with respect to the predetermined noise level matches the stored level of the output signal of the first vibration detection sensor. It is characterized in that to correct the level of the output signal of the detection sensor.
[0013]
In this case, the specific position may be a position around the internal combustion engine at a predetermined distance from the internal combustion engine, and a position at which the maximum or minimum sound pressure of the internal combustion engine under predetermined operating conditions can be measured. can do. Further, the predetermined distance is increased as the microphone having higher directivity is used.
[0014]
According to a second aspect of the invention, there is provided a method of correcting an output signal of a vibration detection sensor according to the present invention, wherein a microphone installed at a specific position near an internal combustion engine is used in accordance with the engine speed of the internal combustion engine. Measuring the measured sound pressure level, comparing the sound pressure level corresponding to the engine speed obtained by the measurement with a reference sound pressure level preset according to the engine speed, and Determining that the internal combustion engine is a loud noise internal combustion engine when the pressure is higher than the reference sound pressure level, and determining the internal combustion engine as a low noise internal combustion engine when the pressure is lower than the reference sound pressure level; and a vibration detection sensor installed in the internal combustion engine. Calculating the effective value of the sound pressure of the engine vibration according to the engine speed of the internal combustion engine using the output signal from the engine, and calculating the effective sound pressure value according to the engine speed according to the engine speed. Preset A basic step of comparing with the calculated reference sound pressure effective value, and furthermore, when the calculated sound pressure effective value is larger than the reference sound pressure effective value and the internal combustion engine is a low-noise internal combustion engine. Determining that the vibration detection sensor has high sensitivity; and calculating a correction coefficient smaller than 1 and multiplying the calculated correction coefficient by the effective sound pressure value when the vibration detection sensor is determined to be high sensitivity. And correcting the sound pressure effective value.
[0015]
Furthermore, in a third mode of the method of correcting an output signal of a vibration detection sensor according to the present invention, which achieves the above object, in addition to the basic steps of the second mode, the calculated sound pressure effective value is equal to the reference sound pressure. When the internal combustion engine is smaller than the effective value and the internal combustion engine is a loud noise, the vibration detection sensor determines that the sensitivity is low. When the vibration detection sensor is determined to be low sensitivity, a correction coefficient greater than 1 is calculated. And correcting the effective sound pressure value by multiplying the effective sound pressure value by the calculated correction coefficient.
[0016]
Still further, the second and third embodiments further include a step of storing the calculated correction coefficient in association with the engine speed at the time of calculation, and a step of calculating a sound calculated from an output signal of the vibration detection sensor at a predetermined engine speed. Correcting the sound pressure effective value by reading and multiplying the effective pressure value by a correction coefficient at the same engine speed.
[0017]
The reference sound pressure level and the reference sound pressure effective value preset according to the engine speeds of the second and third modes are
(1) having a characteristic that increases linearly according to the engine speed;
(2) map values plotted according to the engine speed;
(3) It is an actual measurement value actually measured according to the engine speed of a certain reference internal combustion engine.
Any of
[0018]
Further, in the second embodiment, the section for calculating the effective value of the engine vibration using the vibration detection sensor is a section between (720 ° CA / number of cylinders) from the top dead center of the cylinder in the combustion stroke. This section can be a variable section.
[0019]
The above-described correction coefficient is a first coefficient determined by (sound pressure level / reference sound pressure level) with respect to a sound pressure level corresponding to the engine speed of the internal combustion engine obtained from the microphone; The sound pressure effective value of engine vibration according to the engine speed of the internal combustion engine obtained from the sensor is determined by multiplying the second coefficient defined by (reference sound pressure effective value / sound pressure effective value). be able to.
[0020]
On the other hand, a device for calculating a correction coefficient of an output signal of a vibration detection sensor according to the present invention, which achieves the above object, includes a microphone installed at a specific position near a first internal combustion engine, and a main body of the first and second internal combustion engines. First and second vibration detection sensors installed, means for storing a first sound pressure level corresponding to the engine speed of the first internal combustion engine, and a second sensor corresponding to the engine speed of the first internal combustion engine. Means for storing the effective sound pressure value of the first internal combustion engine and a microphone located at the same position as the specific position of the second internal combustion engine, and a second microphone corresponding to the engine speed of the second internal combustion engine obtained from the microphone. Means for measuring the sound pressure level of the second internal combustion engine, and vibration detection according to the engine speed of the second internal combustion engine obtained from a second vibration detection sensor attached to the same position as the first internal combustion engine Means for calculating a second effective sound pressure value from the value, Means for comparing the measured value of the second sound pressure level according to the number with the stored value of the first sound pressure level at the same rotation speed, and calculating the second effective sound pressure value according to the engine speed Means for comparing the value with a stored value of the first effective sound pressure value at the same rotation speed, and calculation means for calculating a correction coefficient for multiplying an output signal from the second vibration detection sensor corresponding to the engine speed. It is characterized by comprising.
[0021]
In the first form of the correction coefficient calculating means, the second sound pressure effective value at a certain engine speed of the second internal combustion engine is larger than the first sound pressure effective value, and the second sound pressure When the value is smaller than the level, the correction coefficient is set to a value smaller than 1. In a second form of the correction coefficient calculating means, the second sound pressure effective value at a certain engine speed of the second internal combustion engine is smaller than the first sound pressure effective value, and the second sound pressure When the level is larger than the level, the correction coefficient is set to a value larger than 1.
[0022]
Note that the correction coefficient calculation device for the output signal of the vibration detection sensor may further include a storage unit for the calculated correction coefficient. Further, the correction coefficient is obtained by dividing a value obtained by dividing a second sound pressure level corresponding to the engine speed of the internal combustion engine obtained from the microphone by the first sound pressure level and a first sound pressure effective value into a second sound pressure value. It can be expressed as the product of the values divided by the effective sound pressure value.
[0023]
According to the method for correcting the output signal of the vibration detection sensor and the correction coefficient calculation device for the output signal of the vibration detection sensor according to the present invention, the knock sensor signal output from the different internal combustion engine is output as the vibration sound actually audible to the ear. In the case of the same internal combustion engine vibration, the same output signal is obtained from the knock sensor, so that the knocking control can be reliably performed.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail based on specific examples with reference to the accompanying drawings.
[0025]
FIG. 1 shows a knock determination apparatus 10 for an internal combustion engine, showing a configuration of an embodiment for performing a method of correcting an output signal of a vibration detection sensor according to the present invention in the internal combustion engine 1. The cylinder block of the internal combustion engine 1 is provided with a vibration detection sensor (hereinafter referred to as a knock sensor) 2 as vibration detection means for detecting combustion vibration generated in the internal combustion engine 1. A knock signal of engine 1 is input to knock determination device 10. The knock determination device 10 can be configured by a data analysis device or an electronic control unit (ECU).
[0026]
Further, a microphone 3 for detecting noise of the internal combustion engine 1 is provided near the internal combustion engine 1. A signal indicating the magnitude of noise generated by the internal combustion engine 1 detected by the microphone 1 is input to the knock determination device 10. Further, an operation state parameter indicating the operation state of the internal combustion engine 1 is input to the knock determination device 10. The operating state parameters include an engine speed of the internal combustion engine 1, a cooling water temperature, an engine load, an intake air temperature, and the like.
[0027]
FIG. 2 is a flowchart showing a method of setting a reference value in the method of correcting the output signal of knock sensor 2 performed by knock determination device 10 shown in FIG. In this embodiment, the reference value is an actually measured value in the reference internal combustion engine. That is, the reference value of the noise detection level of the microphone is based on the detection value of one microphone (reference microphone) installed around the reference internal combustion engine, and the reference value for determining the magnitude of the output signal from the knock sensor is The sound pressure effective value in the gate section of the output signal of the reference knock sensor attached to the reference internal combustion engine is used. The gate section is a period for detecting knocking of the internal combustion engine, and the gate section is set to include a part of the combustion stroke of the internal combustion engine.
[0028]
For example, this gate section can be set as a section between (720 ° CA / number of cylinders) and the top dead center of a cylinder in a combustion stroke. The length of this gate section can be made variable so as to avoid other vibrations that occur even when knocking does not occur. If the gate section is narrowed to a range where knocking occurs, a signal having a better S / N can be obtained, and the reference value becomes accurate.
[0029]
In step 101, a knock sensor is attached to a prescribed position of the reference internal combustion engine body. The prescribed position of the internal combustion engine body may be, for example, the center of the cylinder block. In the following step 102, a reference microphone (hereinafter simply referred to as a microphone) is installed at a specific position near the reference internal combustion engine. For example, the microphone 2 is located around the reference internal combustion engine 1 indicated by a broken line in FIG. 4A, at a point where the noise detection output of the reference internal combustion engine 1 by the microphone 2 is maximum or minimum. Good.
[0030]
The microphone 2 may be either unidirectional or acutely directional, but as shown in FIG. 4B, the microphone 2 is unidirectional. Assuming that the distance from the reference internal combustion engine 1 to the microphone 2 is D1, when the microphone 2 with sharp directivity is used, the distance from the reference internal combustion engine 1 to the microphone 2 is a longer distance D2.
[0031]
When the knock sensor and the microphone are installed in the reference internal combustion engine, in step 103, the reference internal combustion engine is operated under specified operating conditions. The specified operating conditions are operating conditions under which knocking does not occur in the internal combustion engine.
[0032]
In step 104, the noise level of the reference internal combustion engine detected by the microphone is stored as a reference value. This noise level may be measured and stored for each predetermined engine speed of the reference internal combustion engine. In the next step 105, the signal from the knock sensor is sampled and read in the gate section. The signal from the knock sensor may be measured and stored for each predetermined engine speed of the reference internal combustion engine. Then, in step 106, the sound pressure effective value in the gate section is calculated as the reference sound pressure effective value, and in the next step 107, this reference sound pressure effective value is stored.
[0033]
The noise level and the reference sound pressure effective value of the reference internal combustion engine stored in this manner are used for correcting the output signal from the knock sensor attached to another internal combustion engine. The microphone used to correct the output signal from the knock sensor attached to another internal combustion engine is the same as the microphone used to measure the noise of the reference internal combustion engine, and the same position as that of the reference internal combustion engine is used. To detect noise. An example of a method of correcting an output signal from a knock sensor attached to such an internal combustion engine in the present invention will be described next with reference to FIG.
[0034]
When correcting the output signal from the knock sensor attached to the internal combustion engine, in step 201, the knock sensor is attached to a specified position of the internal combustion engine body. The prescribed position of the internal combustion engine body may be the same as that of the reference internal combustion engine, and may be, for example, the center of the cylinder block. In the following step 202, the same microphone as the microphone used for the reference internal combustion engine is installed at a specific position near the internal combustion engine. The microphone is installed at the same position as the position installed with respect to the reference internal combustion engine.
[0035]
When the knock sensor and the microphone are installed in the internal combustion engine, in step 203, the internal combustion engine is operated under specified operating conditions. The specified operating conditions are the same as the operating conditions of the reference internal combustion engine, and are operating conditions in which knocking does not occur in the internal combustion engine.
[0036]
In step 204, the noise level of the internal combustion engine is detected by the microphone. The noise level of the internal combustion engine may be detected for each predetermined engine speed of the internal combustion engine. In this case, the detected value is stored. In the next step 205, the signal from the knock sensor is sampled and read in the gate section. The signal from the knock sensor may be measured and stored for each predetermined engine speed of the internal combustion engine. Then, in step 206, the sound pressure effective value in the gate section is calculated. This gate section can be set at 720 ° / number of cylinders from the top dead center of the combustion cylinder, but can be made variable in a direction narrower than this in order to avoid vibrations generated in a state where knocking does not occur. When the noise level of the internal combustion engine is detected for each predetermined engine speed of the internal combustion engine, these are stored.
[0037]
In step 207, it is determined whether the detected noise level is the same as the noise level in the reference internal combustion engine. If the noise levels are the same, the process proceeds to step 208, where a first correction coefficient K1 is calculated to make the effective sound pressure value calculated in step 206 equal to the effective reference sound pressure value of the reference internal combustion engine. Then, in a step 212, the first correction coefficient K1 is stored, and the routine ends.
[0038]
On the other hand, if it is determined in step 207 that the detected noise level is not equal to the noise level in the reference internal combustion engine, the process proceeds to step 209. In step 209, a second correction coefficient K2 is calculated by dividing the detected noise level by the reference value. In the next step 210, the reference sound pressure effective value is corrected by multiplying the read value of the reference sound pressure effective value by the second correction coefficient K2 to calculate a corrected reference sound pressure effective value. The corrected reference sound pressure effective value increases when the detected noise level is higher than the reference value, and decreases when the detected noise level is lower than the reference value.
[0039]
Then, in step 211, a first correction coefficient K1 is calculated which makes the sound pressure effective value calculated in step 206 equal to the corrected reference sound pressure effective value calculated in step 210. Then, in step 212, the first correction coefficient K1 is stored in any one of the memories of the knock determination device 10 shown in FIG. 1, and the routine ends. If the reference value of the noise level and the reference sound pressure effective value are measured and stored for each predetermined engine speed of the internal combustion engine, the procedure from step 207 to step 212 is repeated for each engine speed, and The first correction coefficient K1 for each rotation speed may be stored in the memory.
[0040]
When the first correction coefficient K1 is calculated and stored in the memory in this manner, the microphone 3 used for the measurement is removed from the knock determination device 10. Thereafter, knock determination device 10 determines whether knocking has occurred based on a value obtained by correcting the sound pressure effective value of the output signal from knock sensor 2 with this first correction coefficient K1. Further, when the first correction coefficient is calculated for each engine speed of the internal combustion engine, the sound pressure effective value of the output signal from the knock sensor 2 is corrected by the first correction coefficient corresponding to the engine speed of the internal combustion engine. Just do it.
[0041]
As a result, the effective sound pressure value of the output signal from knock sensor 2 is corrected in accordance with the sensitivity of the knock sensor, so that knock determination in knock determination device 10 can be accurately performed.
[0042]
FIG. 5A is a block diagram showing a configuration of an embodiment of the correction coefficient calculating device 20 of the present invention provided in the knock detecting device 10 shown in FIG. The correction coefficient calculation device 20 calculates a correction coefficient K for correcting the output signal of the vibration detection sensor. The output signal of the knock sensor 2, the output signal of the microphone 3, and the engine speed signal NE from the engine speed sensor SN are input to the correction coefficient calculation device 20. An input / output interface (abbreviated as I / F in the figure) 21 that converts an input signal into a signal that can be processed inside the device, outputs a correction coefficient K, and temporarily stores data inside the correction coefficient calculation device 20. There are a RAM 22 for temporarily storing, a ROM 26 for storing fixed data and programs, a filter 9 for limiting the frequency of an input signal from the knock sensor 2, a CPU 25 for calculating a correction coefficient, and the like. Interconnected.
[0043]
FIG. 5B is a block diagram showing the internal functions of the correction coefficient calculation device 20 shown in FIG. Inside the correction coefficient calculating device 20, the microphone sound pressure reference value storage means 4 and the reference sound pressure effective value storage means 5, the microphone sound pressure measurement means 6, the microphone sound pressure comparison means 7, the sound pressure effective value comparison means 8, There are a filter unit 9, a correction coefficient K1 calculation unit 11, a correction coefficient storage unit 12 for each rotation speed, a gate section setting unit 13, and a sound pressure effective value calculation unit 14.
[0044]
The microphone sound pressure reference value storage means 4 and the reference sound pressure effective value storage means 5 are provided in the ROM 23. In this embodiment, the microphone sound pressure reference value storage means 4 stores a reference value of a noise level (hereinafter referred to as a microphone sound pressure) as a reference for determining a noise level detected by the microphone 3 for each predetermined engine speed in this embodiment. ing. Further, the reference sound pressure effective value storage means 5 stores a reference sound pressure effective value for determining the magnitude of the effective value of the output signal from the knock sensor 2 for each predetermined engine speed in this embodiment. .
[0045]
As shown in FIG. 8A, the reference value according to the engine speed of the microphone sound pressure stored in the microphone sound pressure reference value storage means 4 has a characteristic that linearly increases according to the engine speed. A method of setting a reference value, a method of setting a map value plotted according to the engine speed as shown in FIG. 8B as a reference value, and a method of setting a reference internal combustion engine as shown in FIG. There is a method in which an actual measurement value measured according to the rotation speed is used as a reference value. In the embodiment of the present invention, when the microphone sound pressure detected by the microphone 3 is higher than the reference value of the microphone sound pressure, when the internal combustion engine is a noisy engine and is lower than the reference value of the microphone sound pressure. Has determined that the internal combustion engine is a low noise engine.
[0046]
On the other hand, as shown in FIG. 9A, the rotation reference sound pressure effective value according to the engine speed stored in the reference sound pressure effective value storage means 5 increases linearly according to the engine speed. A method using a characteristic as a reference value, a method using a map value plotted according to the engine speed as shown in FIG. 9B as a reference value, and a method using a certain internal combustion engine as shown in FIG. There is a method in which an actually measured value according to the engine speed is used as a reference value. In the embodiment of the present invention, when the effective sound pressure value in the gate section of the output detected by the knock sensor 2 is larger than the reference effective sound pressure value, the sensitivity of the knock sensor 2 is good and the sensitivity is high. When it is smaller than the effective sound pressure value, it is determined that the sensitivity of knock sensor 2 is low and the sensitivity is low.
[0047]
The microphone sound pressure measuring means 6 measures the microphone sound pressure corresponding to the engine speed at that time from the output signal of the microphone 3. The microphone sound pressure measured by the microphone sound pressure measuring means 6 is input to the microphone sound pressure comparing means 7. The microphone sound pressure comparison means 7 receives the microphone sound pressure reference value from the microphone sound pressure reference value storage means 4 and measures the microphone sound pressure reference value corresponding to the current engine speed. Microphone sound pressure is compared.
[0048]
On the other hand, the vibration detection output detected by knock sensor 2 is input to sound pressure effective value calculating means 14 after its frequency is adjusted by filter means 9. Further, the gate section setting means 13 calculates a gate section for determining knocking based on the input operating state parameters of the internal combustion engine, and inputs this to the sound pressure effective value calculating means 14. The sound pressure effective value calculating means 14 calculates the sound pressure effective value from the output signal of the knock sensor in the gate section input from the gate section setting means 13. The effective sound pressure value calculated by the effective sound pressure calculating means 14 is input to the effective sound pressure comparing means 8. A reference sound pressure effective value storage means 5 is connected to the sound pressure effective value comparing means 8, and the reference sound pressure effective value corresponding to the engine speed at this time is compared with the calculated sound pressure effective value. You.
[0049]
The comparison result of the microphone sound pressure comparison means 7 and the comparison result of the sound pressure effective value comparison means 8 are input to the correction coefficient calculation means 11 where the correction coefficient K of the effective value of the output signal of the knock sensor is It is calculated corresponding to the engine speed of the internal combustion engine. The correction coefficient K1 of the effective value of the output signal of the knock sensor calculated by the correction coefficient K calculation means 11 is input to and stored in the correction coefficient storage means 12 for each engine speed. The correction coefficient K stored in the correction coefficient storage means 12 for each engine speed is transferred to another memory of the knock determination device 10 shown in FIG. 1 or becomes unnecessary after the calculation of the correction coefficient K. The microphone 3 remains stored in the correction coefficient storage means 12 of the correction coefficient calculation device 20 from which the microphone 3 has been removed.
[0050]
When the correction coefficient calculation device 20 remains after the calculation of the correction coefficient K, as shown in FIG. 5B, a function of causing the correction coefficient storage unit 12 to output the correction coefficient K according to the input of the engine speed NE. Should be provided. When the multiplier 15 multiplies the correction coefficient K from the correction coefficient storage 12 by the sound pressure effective value at this engine speed from the sound pressure effective value calculator 14, the corrected sound at this engine speed is obtained. The effective pressure value can be obtained.
[0051]
Here, an embodiment of a method of calculating the output correction value of the knock sensor 2 by the correction coefficient calculation device 20 for the output signal of the knock sensor 2 will be described with reference to the flowchart shown in FIG. The procedure of the flowchart shown in FIG. 6 shows only a method of calculating the output correction coefficient K of the knock sensor at a certain engine speed of the internal combustion engine. When this procedure is completed, the engine speed of the internal combustion engine is increased by a predetermined speed, and the output signal of the knock sensor 2 of the internal combustion engine according to the next engine speed is obtained in exactly the same procedure as the procedure of the flowchart of FIG. The correction coefficient K is calculated. The calculated correction coefficient K of the output signal of the knock sensor 2 of the internal combustion engine at each engine speed is sequentially stored in the correction coefficient storage means 12 for each speed shown in FIG.
[0052]
In step 301, the noise generated by the internal combustion engine at this engine speed is measured as a microphone sound pressure using a microphone. Then, in the next step 302, it is determined whether or not the measured microphone sound pressure exceeds the microphone sound pressure reference value. The microphone sound pressure reference value is read from the microphone sound pressure reference value storage means 4 described with reference to FIG. Any of the characteristics shown in FIGS. 8A to 8C is stored in the microphone sound pressure reference value storage means 4, and the microphone sound pressure reference value corresponding to the engine speed at this time is read.
[0053]
If the measured microphone sound pressure is higher than the reference value, the routine proceeds to step 303, where it is determined that the internal combustion engine is a loud one, and the routine proceeds to step 305. On the other hand, when it is determined in step 302 that the microphone sound pressure is equal to or lower than the reference value, the process proceeds to step 304. Here, it is determined that the internal combustion engine is a low noise engine and the process proceeds to step 305.
[0054]
In step 305, the sound pressure effective value is calculated from the output signal of the knock sensor in the gate section in the normal state where knocking does not occur. This gate section can be set at 720 ° / number of cylinders from the top dead center of the combustion cylinder, but can be made variable in a direction narrower than this in order to avoid vibrations generated in a state where knocking does not occur. After calculating the effective sound pressure value in step 305, the process proceeds to step 306, and it is determined whether the calculated effective sound pressure value is larger than the reference effective sound pressure value. This sound pressure effective value is read from the reference sound pressure effective value storage means 5 in FIG. Any of the characteristics shown in FIGS. 9A to 9C is stored in the reference sound pressure effective value storage means 5, and the reference sound pressure effective value corresponding to the engine speed at this time is read out. When it is determined in step 306 that the effective sound pressure value is larger than the reference effective sound pressure value, the process proceeds to step 307, in which it is determined whether or not the internal combustion engine is a loud engine. If it is determined in step 306 that the effective sound pressure value is equal to or smaller than the reference effective sound pressure value, the process proceeds to step 310 to determine whether the internal combustion engine is a loud noise engine.
[0055]
If it is determined in step 307 that the internal combustion engine is a low noise engine, the process proceeds to step 308, in which it is determined that the knock sensor has high sensitivity, and the correction coefficient K at this engine speed is calculated by the following equation (A). .
[0056]
K = (b ÷ a) × (d ÷ c) (A)
Here, the symbols a and b are the microphone sound pressure reference values shown in FIGS. 10A and 10B and the measured microphone sound pressure, and the symbols c and d are the calculations shown in FIGS. 11A and 11B. The effective sound pressure value and the reference effective sound pressure value. Accordingly, since the correction coefficient K calculated in step 308 is calculated using the values indicated by the signs a and b in FIG. 10B and the values indicated by the signs c and d in FIG. The value is smaller than.
[0057]
Then, in step 313, the calculated correction coefficient K is stored in association with the engine speed at this time. The storage destination at this time is the correction coefficient storage unit 12 for each rotation speed described with reference to FIG.
[0058]
On the other hand, when it is determined in step 307 that the internal combustion engine is a loud noise engine, the process proceeds to step 309, in which it is determined that the knock sensor has the normal sensitivity. . This is because the calculation of equation (A) is based on the values (b / a> 1) indicated by reference signs a and b in FIG. 10A and the values (d / c) indicated by reference signs c and d in FIG. This is because the calculation is performed using <1), and the calculation result is almost 1. Then, in step 313, the calculated correction coefficient K is stored in association with the engine speed at this time, and this routine ends.
[0059]
If the internal combustion engine is determined to be a loud noise engine in the determination of step 310 that proceeds when the effective sound pressure value is equal to or less than the reference effective sound pressure value, the process proceeds to step 311 and determines that the knock sensor has low sensitivity. The correction coefficient K at this engine speed is calculated by the aforementioned equation (A). The correction coefficient K calculated in step 311 is calculated using the values indicated by the signs a and b in FIG. 10A and the values indicated by the signs c and d in FIG. This is a large value. Then, in step 313, the calculated correction coefficient K is stored in association with the engine speed at this time, and this routine ends.
[0060]
On the other hand, if it is determined in step 311 that the internal combustion engine is a low noise engine, the process proceeds to step 312, where it is determined that the knock sensor has normal sensitivity, and the correction coefficient K at this engine speed is set to 1 and the process proceeds to step 313. . This is because the calculation of the expression (A) is based on the values of the signs a and b (b / a <1) in FIG. 10B and the values of the signs c and d (d / c> 1) in FIG. ), The calculation result is almost 1. Then, in step 313, the calculated correction coefficient K is stored in association with the engine speed at this time, and this routine ends.
[0061]
After the correction coefficient K of the effective value of the sound pressure of the output signal of the knock sensor 2 is calculated for each engine speed as described above, the correction coefficient K is multiplied by the effective value of the sound pressure of the output signal of the knock sensor 2. By doing so, the effective sound pressure value of the output signal of knock sensor 2 can be corrected, and accurate knocking determination can be made. This procedure will be described with reference to the flowchart of FIG.
[0062]
In step 401, the engine speed NE of the internal combustion engine is read, and in the next step 402, the effective sound pressure value in the gate section is calculated from the output signal of the knock sensor 2. Next, a correction coefficient K corresponding to the engine speed read in step 401 is read, and the routine proceeds to step 404. In step 404, the corrected sound pressure effective value is calculated by multiplying the sound pressure effective value calculated in step 402 by the correction coefficient K read in step 403.
[0063]
In step 405, the corrected effective sound pressure value is compared with the knock determination value. If (corrected sound pressure effective value)> (knock determination value), the process proceeds to step 406, where it is determined that knocking has occurred in the internal combustion engine. The lever routine ends. On the other hand, if the determination in step 405 is (corrected sound pressure effective value) ≦ (knock determination value), the process proceeds to step 407, where it is determined that knocking has not occurred in the internal combustion engine, and this routine ends.
[0064]
As described above, the correction coefficient K calculated for each engine speed by the method for correcting the output signal of the knock sensor and the correction coefficient calculation device for the output signal of the knock sensor of the present invention is used to calculate the output signal of the knock sensor. By multiplying the effective sound pressure value, the effective sound pressure value obtained from the knock sensor is always correct, so that it is possible to accurately determine whether knocking has occurred in the internal combustion engine.
[0065]
【The invention's effect】
According to the method for correcting an output signal of a vibration detection sensor and the correction coefficient calculation device for an output signal of a vibration detection sensor of the present invention, the following effects are obtained.
(1) Since the output signal of the knock sensor is corrected by the sound pressure data acquired by the microphone, the effective value of the output signal of the knock sensor having the same volume can be calculated for the internal combustion engine having the same volume. Knocking can be accurately determined.
(2) By selecting the installation position of the microphone from several patterns, it is possible to accurately measure the sound pressure even in the case of different internal combustion engines.
(3) The output signal of the knock sensor is multiplied by a correction coefficient of the effective sound pressure value stored in advance in accordance with the engine speed of the internal combustion engine to thereby correct the output signal of the knock sensor. Since the comparison can be made based on the same reference regardless of the type, the output signal of the knock sensor is always reliable.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a configuration of a knock determination device for an internal combustion engine in which a method for correcting an output signal of a vibration detection sensor according to the present invention is implemented.
FIG. 2 is a flowchart showing a method of setting a reference value in a method of correcting an output signal of a vibration detection sensor performed by the knock determination device shown in FIG.
3 is a flowchart illustrating a method of correcting an output signal of a vibration detection sensor according to an embodiment of the present invention, among methods of correcting an output signal of the vibration detection sensor performed by the knock determination device illustrated in FIG. 1;
4A is a diagram for explaining the installation position of a microphone in the knock determination device of FIG. 1, and FIG. 4B is a diagram showing a case where a unidirectional microphone is used as the microphone shown in FIG. FIG. 9 is a diagram illustrating a difference in the installation position of the microphone from the internal combustion engine when the microphone is used.
5A is a block diagram showing the configuration of an embodiment of a device for calculating a correction coefficient of an output signal of a vibration detection sensor according to the present invention, and FIG. 5B is a diagram for correcting the output signal of the vibration detection sensor of FIG. FIG. 3 is a block diagram showing the internal functions of the coefficient calculation device.
6 is a flowchart showing one embodiment of a method of calculating an output correction value of a vibration detection sensor in the device of FIG.
FIG. 7 is a flowchart illustrating a procedure for determining knocking of the internal combustion engine using the correction coefficient calculated by the method and the apparatus of the present invention.
8A and 8B show examples of determination reference values for a noisy engine and a low-noise engine in the flowchart of FIG. 6, and FIG. 8A shows a case where the determination reference value increases linearly with respect to the engine speed. Is a diagram showing an example in which the reference value is plotted at a predetermined value with respect to the engine speed, and (c) is a reference internal combustion having a reference value. It is a diagram showing an example which is an actual measurement value in the engine.
9 shows an example of a reference value for judging the magnitude of the effective value of the vibration of the knock sensor in the flowchart of FIG. 6; FIG. 9A shows that the reference sound pressure effective value increases linearly with respect to the engine speed; (B) is a diagram illustrating an example in which the reference sound pressure effective value is plotted at a predetermined value with respect to the engine speed, and (c) is a diagram illustrating the reference sound pressure. FIG. 7 is a diagram illustrating an example in which an effective value is an actually measured value in a reference internal combustion engine.
10A is a diagram illustrating a method of calculating a correction value when the sound pressure of a microphone is large in an engine with a large noise, and FIG. 10B is a diagram illustrating a correction value when the sound pressure of the microphone is small in an engine with a small noise. It is a figure showing a calculation method.
11A is a diagram illustrating a method of calculating a correction value when the effective value of the sensor output of the vibration detection sensor having a small output is small, and FIG. 11B is a diagram illustrating the effectiveness of the sensor output of the vibration detection sensor having a large output; FIG. 7 is a diagram illustrating a method of calculating a correction value when the value is large.
[Explanation of symbols]
1. Internal combustion engine
2 ... Vibration detection means (knock sensor)
3. Microphone
4: Microphone sound pressure reference value storage means
5. Reference sound pressure effective value storage means
6 ... Microphone sound pressure measuring means
7. Microphone sound pressure comparison means
8 ... Sound pressure effective value comparison means
9 ... Filter (filter means)
10. Knock determination device
11 correction coefficient calculating means
12... Correction coefficient storage means for each rotation speed
13: Gate section setting means
14 ... Sound pressure effective value calculating means

Claims (19)

The first internal combustion engine is operated in a state where a microphone is installed at a specific position, and a noise level detected by the microphone is made to correspond to an output signal of a first vibration detection sensor attached to the first internal combustion engine. Remember,
A second internal combustion engine different from the first internal combustion engine is operated with the same microphone as in the first internal combustion engine installed at the same position as the specific position, and the noise level is detected. And detecting an output signal of a second vibration detection sensor attached to the same position as that of the first internal combustion engine of the second internal combustion engine,
The output signal of the second vibration detection sensor is adjusted so that the level of the output signal of the second vibration detection sensor with respect to a predetermined noise level matches the stored level of the output signal of the first vibration detection sensor. A method for correcting an output signal of a vibration detection sensor, comprising correcting a level. The specific position is a position around the internal combustion engine separated by a predetermined distance from the internal combustion engine, and is a position where a maximum or minimum sound pressure of the internal combustion engine under predetermined operating conditions can be measured. The method for correcting an output signal of a vibration detection sensor according to claim 1. 3. The method according to claim 2, wherein the predetermined distance is set such that the distance increases as the microphone having a higher directivity is used. Using a microphone installed at a specific position near the internal combustion engine, measuring a sound pressure level according to the engine speed of the internal combustion engine,
Comparing the sound pressure level according to the engine speed obtained by the measurement with a reference sound pressure level preset according to the engine speed,
When the measured sound pressure level is higher than the reference sound pressure level, the internal combustion engine is determined to be a high-noise internal combustion engine, and when the measured sound pressure level is lower than the reference sound pressure level, the internal combustion engine is determined to be a low-noise internal combustion engine;
Using an output signal from a vibration detection sensor installed in the internal combustion engine, calculating a sound pressure effective value of engine vibration according to the engine speed of the internal combustion engine,
Comparing the sound pressure effective value calculated according to the engine speed with a reference sound pressure effective value set in advance according to the engine speed;
When the calculated sound pressure effective value is larger than the reference sound pressure effective value and the internal combustion engine is a low-noise internal combustion engine, the vibration detection sensor determines high sensitivity,
Calculating a correction coefficient smaller than 1 when the vibration detection sensor is determined to be highly sensitive, and correcting the sound pressure effective value by multiplying the calculated correction coefficient by the sound pressure effective value; And a method of correcting an output signal of the vibration detection sensor. Using a microphone installed at a specific position near the internal combustion engine, measuring a sound pressure level according to the engine speed of the internal combustion engine,
Comparing the sound pressure level according to the engine speed obtained by the measurement with a reference sound pressure level preset according to the engine speed,
When the measured sound pressure level is higher than the reference sound pressure level, the internal combustion engine is determined to be a high-noise internal combustion engine, and when the measured sound pressure level is lower than the reference sound pressure level, the internal combustion engine is determined to be a low-noise internal combustion engine;
Using an output signal from a vibration detection sensor installed in the internal combustion engine, calculating a sound pressure effective value of engine vibration according to the engine speed of the internal combustion engine,
Comparing the sound pressure effective value calculated according to the engine speed with a reference sound pressure effective value set in advance according to the engine speed;
When the calculated sound pressure effective value is smaller than the reference sound pressure effective value and the internal combustion engine is a high-noise internal combustion engine, the vibration detection sensor determines that the sensitivity is low,
When the vibration detection sensor is determined to have low sensitivity, calculating a correction coefficient having a value greater than 1 and correcting the sound pressure effective value by multiplying the calculated correction coefficient by the sound pressure effective value; And a method of correcting an output signal of the vibration detection sensor. Storing the calculated correction coefficient in association with the engine speed at the time of calculation, and
Correcting the sound pressure effective value by reading and multiplying the sound pressure effective value calculated from the output signal of the vibration detection sensor at a predetermined engine speed by the correction coefficient at the same engine speed. The method for correcting an output signal of a vibration detection sensor according to claim 4, wherein the output signal is provided. The vibration according to any one of claims 4 to 6, wherein the reference sound pressure level preset according to the engine speed has a characteristic that increases linearly according to the engine speed. A method for correcting the output signal of the detection sensor. The vibration detection according to any one of claims 4 to 6, wherein the reference sound pressure level preset according to the engine speed is a map value plotted according to the engine speed. A method of correcting the output signal of the sensor. 7. The method according to claim 4, wherein the reference sound pressure level preset according to an engine speed is an actual measurement value measured according to an engine speed of a predetermined internal combustion engine. The correction method of the output signal of the vibration detection sensor described in the above. The section in which the effective value of engine vibration is calculated using the vibration detection sensor is a section between (720 ° CA / number of cylinders) from a top dead center of a cylinder in a combustion stroke. 10. The method of correcting an output signal of a vibration detection sensor according to any one of 4 to 9. The method of correcting an output signal of a vibration detection sensor according to claim 10, wherein a section for calculating an effective value of engine vibration using the vibration detection sensor is variable. 12. The device according to claim 4, wherein the reference sound pressure effective value preset according to the engine speed has a characteristic that increases linearly according to the engine speed. A method for correcting the output signal of the vibration detection sensor. 12. The vibration according to claim 4, wherein the reference sound pressure effective value preset according to the engine speed is a map value plotted according to the engine speed. A method for correcting the output signal of the detection sensor. 12. The method according to claim 4, wherein the reference sound pressure effective value preset according to an engine speed is an actual measurement value measured according to an engine speed of a reference internal combustion engine. 3. The method for correcting an output signal of a vibration detection sensor according to item 1. A first coefficient determined by (sound pressure level / reference sound pressure level) with respect to a sound pressure level corresponding to an engine speed of the internal combustion engine obtained from the microphone; The sound pressure effective value according to the engine speed of the internal combustion engine obtained from the sensor is multiplied by a second coefficient determined by (reference sound pressure effective value / sound pressure effective value). The method of correcting an output signal of a vibration detection sensor according to any one of claims 4 to 6, wherein: A microphone installed at a specific position near the first internal combustion engine;
First and second vibration detection sensors installed at the same position on the first and second internal combustion engine bodies;
Means for storing a first sound pressure level corresponding to an engine speed of the first internal combustion engine;
Means for storing a first effective sound pressure value according to the engine speed of the first internal combustion engine;
Means for installing the microphone at the same position as the specific position of the second internal combustion engine and measuring a second sound pressure level obtained from the microphone according to the engine speed of the second internal combustion engine When,
From a vibration detection value corresponding to the engine speed of the second internal combustion engine obtained from a second vibration detection sensor attached to the same position of the second internal combustion engine as that of the first internal combustion engine, a second sound is obtained. Means for calculating a pressure effective value;
Means for comparing a measured value of the second sound pressure level according to the engine speed with a stored value of the first sound pressure level at the same speed;
Means for comparing the calculated value of the second effective sound pressure value according to the engine speed with the stored value of the first effective sound pressure value at the same engine speed; and
Calculating means for multiplying an output signal from the second vibration detection sensor corresponding to an engine speed by a correction coefficient calculating means.
When the second effective sound pressure value at a certain engine speed of the second internal combustion engine is larger than the first effective sound pressure value and smaller than the second sound pressure level, the correction coefficient is set to 1 An apparatus for calculating a correction coefficient of an output signal of a vibration detection sensor, wherein the correction coefficient is set to a small value. A microphone installed at a specific position near the first internal combustion engine;
First and second vibration detection sensors installed at the same position on the first and second internal combustion engine bodies;
Means for storing a first sound pressure level corresponding to an engine speed of the first internal combustion engine;
Means for storing a first effective sound pressure value according to the engine speed of the first internal combustion engine;
Means for installing the microphone at the same position as the specific position of the second internal combustion engine and measuring a second sound pressure level obtained from the microphone according to the engine speed of the second internal combustion engine When,
From a vibration detection value corresponding to the engine speed of the second internal combustion engine obtained from a second vibration detection sensor attached to the same position of the second internal combustion engine as that of the first internal combustion engine, a second sound is obtained. Means for calculating a pressure effective value;
Means for comparing a measured value of the second sound pressure level according to the engine speed with a stored value of the first sound pressure level at the same speed;
Means for comparing the calculated value of the second effective sound pressure value according to the engine speed with the stored value of the first effective sound pressure value at the same engine speed; and
Calculating means for multiplying an output signal from the second vibration detection sensor corresponding to an engine speed by a correction coefficient calculating means.
When the second effective sound pressure value at a certain engine speed of the second internal combustion engine is smaller than the first effective sound pressure value and larger than the second sound pressure level, the correction coefficient is set to 1 An apparatus for calculating a correction coefficient of an output signal of a vibration detection sensor, wherein the correction coefficient is set to a large value. 18. The correction coefficient of the output signal of the vibration detection sensor according to claim 16, wherein the correction coefficient calculation device for the output signal of the vibration detection sensor further includes a storage unit for the calculated correction coefficient. Calculation device. The correction coefficient is a value obtained by dividing a second sound pressure level corresponding to an engine speed of the internal combustion engine obtained from the microphone by a first sound pressure level, and the first sound pressure effective value. 19. The correction coefficient calculating device for an output signal of a vibration detection sensor according to claim 16, wherein the correction coefficient is calculated by multiplying a value obtained by dividing by a second effective sound pressure value.

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