JP4266975B2 - Knock detection device - Google Patents

Description

  The present invention relates to a knock detection device, and more particularly to a knock detection device that calculates a threshold value for knock determination based on a detected knock signal of an internal combustion engine.

  There is a knocking control method that detects knocking occurring in the engine and controls the ignition timing in accordance with the knocking detection state (see, for example, Patent Document 1). This knocking control method uses a bandpass filter (BPF) to filter only the frequency components that may contain vibration due to knocking from the output from the knock sensor that detects vibration due to engine knocking, and obtains the peak value. Sampling is performed for each TDC (top dead center). Then, with respect to a value obtained by averaging the sampled peak values (hereinafter referred to as background), the presence or absence of knocking is determined based on whether or not the sampled peak value exceeds a predetermined level, and ignition progress is determined. The angular amount is feedback controlled. If knocking does not occur as a result of the determination, the ignition timing is advanced, and if knocking occurs, feedback control is performed to retard the ignition timing.

  By the way, the background is obtained by averaging the peak values as described above (specifically, the value obtained by adding a predetermined coefficient to the value obtained by subtracting the peak value from the previous background is added to the previous background. Since this addition value (update value is provided with an update guard value), it takes time to converge to a constant value when the engine is started.

FIG. 21 is a diagram for explaining the convergence of the background when the engine is started. As shown in the figure, the peak value is sampled when the engine is started. However, since the background is an average of the peak value, it is updated every TDC and gradually converges to the peak value. If knocking determination is made before the background has completely converged to the peak value (period F in the figure), the peak value may be determined to exceed the predetermined level, and knocking has occurred. Misjudgment. Therefore, conventionally, feedback control of knocking has been started after a certain time has elapsed in consideration of the time for the background to converge.
JP-A-8-218996

  As described above, conventionally, even if the background has converged to the peak value, knocking feedback control is started after a certain period of time, so that the knocking control range has been narrowed. .

  The present invention has been made in view of the above points, and provides a knock detection device capable of appropriately changing the start timing of knock determination so as not to make an erroneous determination of knocking and widening the control range of knocking. For the purpose.

In order to solve the above problem, the present invention provides a knock detection device that detects knocks in an internal combustion engine, and calculates threshold values for knock determination based on a plurality of knock signals of the internal combustion engine. A calculating means, a knock determining means for performing the knock determination based on the threshold value, and the threshold value until the predetermined time corresponding to the temperature at the time of starting the internal combustion engine elapses. And a knock determination control unit that prohibits the knock determination based on the knock detection device.

According to such a knock detection device, knock determination based on the threshold value is prohibited at the start of the internal combustion engine until a predetermined time corresponding to the temperature at the start of the internal combustion engine elapses. Thereby, it is possible to change the start time of knock determination so as not to make a false determination of knocking.

In order to solve the above problem, the present invention provides a knock detection device for detecting knocks of an internal combustion engine, which calculates a threshold value for knock determination based on a plurality of knock signals of the internal combustion engine. Threshold calculation means, knock determination means for performing the knock determination based on the threshold value, and when the internal combustion engine is started, the knock determination based on the threshold value is detected when the internal combustion engine is started There is provided a knock detection device comprising knock determination control means for prohibiting until a predetermined time corresponding to the magnitude of the knock signal elapses.

According to such a knock detection device, when the internal combustion engine is started, knock determination based on the threshold value is prohibited until a predetermined time corresponding to the magnitude of the knock signal detected when the internal combustion engine is started. Thereby, it is possible to change the start time of knock determination so as not to make a false determination of knocking.

In the knock detection device of the present invention, when the internal combustion engine is started, knock determination based on the threshold value is prohibited until a predetermined time corresponding to the temperature at the start of the internal combustion engine elapses. Accordingly, the knock determination start time can be changed so as not to make a knocking determination error, and the knocking control range can be widened.

In the knock detection device of the present invention, at the time of starting the internal combustion engine, knock determination based on the threshold value is prohibited until a predetermined time corresponding to the magnitude of the knock signal detected at the time of starting the internal combustion engine elapses. I made it. Accordingly, the knock determination start time can be changed so as not to make a knocking determination error, and the knocking control range can be widened.

Hereinafter, the principle of the knock detection device according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an outline of a knock detection device. As shown in the figure, the knock detection device 1 includes a peak value acquisition unit 1a, a background calculation unit 1b, a knock determination unit 1c, a temperature acquisition unit 1d, and a knock determination control unit 1e. The knock detection device 1 performs knocking feedback control by controlling the ignition timing of the internal combustion engine 2.

  The peak value acquisition unit 1a acquires the peak value (knock signal) of the vibration of the internal combustion engine 2 during a predetermined period of the rotation period of the crankshaft of the internal combustion engine 2. For example, a knock sensor that detects vibration is fixed to the internal combustion engine 2, and the vibration of the internal combustion engine 2 is acquired from the knock sensor.

  The background calculation means 1b calculates the background (threshold value) by averaging the peak values acquired by the peak value acquisition means 1a. Specifically, the value obtained by adding a predetermined coefficient to the value obtained by subtracting the peak value from the previous background is added to the previous background. For example, an update guard value is provided in the addition value (update value).

  The knock determination unit 1c determines knocking based on whether or not the peak value acquired by the peak value acquisition unit 1a exceeds a predetermined level with respect to the background. Then, knocking of the internal combustion engine 2 is feedback-controlled according to the determination of knocking. For example, if the peak value does not exceed a predetermined level with respect to the background, it is determined that knocking has not occurred, and the ignition timing of the internal combustion engine 2 is advanced. If the peak value exceeds a predetermined level with respect to the background, it is determined that knocking has occurred, and the ignition timing of the internal combustion engine 2 is retarded.

  The temperature acquisition unit 1d acquires the temperature of the internal combustion engine 2 when the internal combustion engine 2 is started, for example, when the starter is turned on. The temperature of the internal combustion engine 2 is, for example, a water temperature, an oil temperature, an intake air temperature, or the like of the internal combustion engine 2, and these temperatures are acquired from a sensor fixed to the internal combustion engine 2.

The knock determination control means 1e prohibits the operation of the knock determination means 1c until a predetermined time corresponding to the temperature of the internal combustion engine 2 acquired by the temperature acquisition means 1d has elapsed.
As described above, when the internal combustion engine 2 is started, knock determination based on the background is prohibited until a predetermined time corresponding to the temperature of the internal combustion engine 2 elapses. Accordingly, the knock determination start time can be changed so as not to make a knocking determination error, and the knocking control range can be widened.

Next, the knock detection device according to the first embodiment will be described in detail with reference to the drawings.
FIG. 2 is a block configuration diagram of the knock detection device according to the first embodiment. As shown in the figure, the knock detection device 10 includes a CPU (Central Processing Unit) 11, a BPF 12, a peak hold amplifier 13, an input interface 14, a RAM (Random Access Memory) 15, a ROM (Read Only Memory) 16, and an output interface 17. have. A knock sensor 21, a water temperature sensor 22, an oil temperature sensor 23, and an intake air temperature sensor 24 are connected to the knock detection device 10. Further, an igniter 31 to which a spark plug 32 is connected is connected.

  The knock sensor 21 is a vibration sensor that converts engine vibration into an electrical signal. The knock sensor 21 is a piezoelectric element, for example, and is fixed to an engine cylinder block or the like.

  The electrical signal output from the knock sensor 21 is input to the BPF 12. The BPF 12 filters only a signal in a frequency band where a signal component due to knocking may appear. The center frequency of the BPF 12 is 4 kHz, for example, and the bandwidth is 1 kHz to 100 kHz.

  A signal filtered by the BPF 12 is input to the peak hold amplifier 13. The peak hold amplifier 13 receives a gate control signal output from the control (CNT) terminal of the CPU 11 and a peak hold reset signal output from the peak hold reset (PHR) terminal of the CPU 11. The peak hold amplifier 13 holds the value while updating the peak value of the signal output from the BPF 12 while the gate control signal is output from the CNT terminal of the CPU 11. When the peak hold reset signal is output from the PHR terminal of the CPU 11, the held peak value is reset. The held peak value is input to the analog / digital conversion (A / D1) terminal of the CPU 11.

  The water temperature sensor 22, the oil temperature sensor 23, and the intake air temperature sensor 24 are sensors that convert the engine water temperature, the oil temperature, and the intake air temperature into electrical signals and output them. Signals from the water temperature sensor 22, the oil temperature sensor 23, and the intake air temperature sensor 24 are input to an analog / digital conversion (A / D2) terminal of the CPU 11 via the input interface 14.

  The RAM 15 and ROM 16 are connected to the CPU 11 via a bus. The RAM 15 temporarily stores at least a part of an OS (Operating System) program to be executed by the CPU 11 and an application program for performing knocking feedback control. The RAM 15 stores various data necessary for processing by the CPU 11. The ROM 16 stores the OS, application programs, various data, and the like. Note that the RAM 15 and the ROM 16 may be built in the CPU 11. The ROM 16 may be a rewritable FLASH memory or the like.

  The igniter 31 is connected to the ignition plug 32 and is connected to the CPU 11 via the output interface 17. The igniter 31 drives and controls the ignition timing of the spark plug 32 in accordance with an instruction from the CPU 11.

  The CPU 11 performs analog / digital conversion on the peak value input to the A / D1 terminal, and performs engine knocking determination. Based on the determination result, the ignition timing of the spark plug 32 is feedback-controlled. Specifically, the CPU 11 advances the ignition timing of the spark plug 32 if knocking does not occur as a result of the determination, and knocks so as to retard the ignition timing of the spark plug 32 if knocking occurs. Has feedback control.

  The CPU 11 can appropriately change the knocking feedback control start time so as not to make an erroneous determination of knocking when the engine is started. For example, after the engine is started, if the background converges quickly to the peak value, the knocking feedback control is started early, and if the background converges slowly, the knocking feedback control is started late. .

  The CPU 11 performs analog / digital conversion on the signals of the water temperature sensor 22, the oil temperature sensor 23, and the intake air temperature sensor 24 input to the A / D2 terminal, and acquires the engine water temperature, the oil temperature, and the intake air temperature. The ROM 16 stores the start time of the feedback control of knocking with respect to the water temperature, oil temperature, and intake air temperature of the engine. The CPU 11 refers to the ROM 16 and the water temperature, oil temperature, and intake temperature acquired from each sensor. The start time of the knocking feedback control with respect to the temperature is calculated.

Next, knocking determination will be described.
FIG. 3 is a waveform diagram for explaining the knocking determination. (A) of the figure shows a waveform input to the peak hold amplifier 13. FIG. 2B shows a waveform output from an engine crank angle sensor, which is not shown in FIG. The pulse output from the crank angle sensor is output every time the piston of the cylinder that is about to enter the ignition stroke reaches TDC. For example, in the case of a 4-cylinder 4-cycle engine, as shown in FIG. It is output every 180 ° CA (crank angle). (C) of the figure shows the waveform of the gate control signal output from the CNT terminal of the CPU 11.

  The peak hold amplifier 13 updates the peak value of the signal output from the BPF 12 by using the gate control signal output from the CPU 11 as a knocking observation period between 10 ° CA and 75 ° CA, and holds the value. . The peak value held by the peak hold amplifier 13 is input to the A / D1 terminal of the CPU 11. After the peak value is input to the CPU 11 and A / D converted, a peak hold reset signal is output from the PHR terminal, and the peak value held by the peak hold amplifier 13 is reset.

  The CPU 11 calculates the background from the peak value subjected to analog / digital conversion. The formula for calculating the background is represented by the following formula (1), for example. BG in formula (1) indicates the background, and the annealing value is a value larger than 1. Note that an update guard value may be provided in the background so as not to change more than a predetermined amount.

BG = Previous BG + (Current peak value−Previous BG) × (1 / Annealing value) (1)
The background is obtained by averaging peak values as shown in Equation (1). The CPU 11 determines whether or not the peak value subjected to the analog / digital conversion this time exceeds a predetermined level with respect to the background obtained by the equation (1), and determines the presence or absence of knocking. An expression for determining the presence or absence of knocking is represented by the following expression (2), for example. K in Equation (2) is a value that is changed according to the engine speed and load.

Y = BG × K (2)
The CPU 11 determines that knocking has occurred when the peak value subjected to analog / digital conversion this time exceeds a value Y obtained by multiplying the background by K. Then, feedback control is performed so as to retard the ignition timing of the spark plug 32 that has been advanced.

  By the way, the background is obtained by averaging the peak values as described above. Therefore, the convergence time for convergence to the background peak value varies depending on the magnitude of the peak value. For example, if the difference between the background and the peak value is large, the convergence time of the background becomes long.

  FIG. 4 is a diagram for explaining the background convergence time. The background and the peak value are shown in (a) and (b) of the figure. The peak value in (a) in the figure is larger than the peak value in (b) in the figure.

  When the engine is started, a peak value is output from the peak hold amplifier 13. The CPU 11 calculates the background according to the above-described equation (1). Since the background is an average of the peak values, it gradually converges to the peak value as shown in FIGS.

  When the difference between the background and the peak value is large, the time for the background to converge is also prolonged. Since the peak value shown in (a) in the figure is larger than the peak value in (b) in the figure, the background convergence time in (a) in the figure is longer than the background convergence time in (b) in the figure. . Therefore, after starting the engine, the CPU 11 changes the start time of the knocking feedback control in accordance with the background convergence time so as not to perform erroneous feedback control due to erroneous determination of knocking. For example, in the case of (a) in the figure, the feedback control of knocking is started at the arrow A1. In the case of (b) in the figure, knocking feedback control is started at the arrow A2.

  Next, the relationship between the engine water temperature, the oil temperature, the intake air temperature, and the start time of the knocking feedback control will be described. As described with reference to FIG. 4, the background convergence time after engine startup depends on the magnitude of the peak value. The magnitude of this peak value varies depending on the state of the engine, and depends on, for example, the water temperature, oil temperature, and intake air temperature described above. Therefore, the CPU 11 obtains the engine water temperature, oil temperature, and intake air temperature from each sensor, and refers to the start time of the knocking feedback control for the engine water temperature, oil temperature, and intake air temperature stored in the ROM 16. Then, the time for starting the control is calculated.

  FIG. 5 is a table showing the relationship between the feedback control start time and the water temperature. As shown in the figure, the water temperature table 41 has columns of water temperature and start time, and stores the start time of knocking feedback control for each water temperature. The unit of the value shown in the water temperature column is ° C., and the unit of the value shown in the start time column is second. The water temperature table 41 is constructed in a storage device such as the ROM 16 shown in FIG.

  The CPU 11 calculates a start time with respect to a certain water temperature of the engine with reference to the water temperature table 41. When the water temperature acquired from the water temperature sensor 22 is between the water temperature columns shown in the water temperature table 41, the start time is calculated by interpolation based on the water temperatures in the columns on both sides. For example, when the water temperature acquired from the water temperature sensor 22 is between 10 ° C. and 30 ° C., the CPU 11 has a start time of 5.1 seconds at 10 ° C. and a start time of 3.1 seconds at 30 ° C. , And the start time for the water temperature acquired from the water temperature sensor 22 is calculated by interpolating these start times.

  FIG. 6 is a table showing the relationship between the feedback control start time and the oil temperature. As shown in the figure, the oil temperature table 42 has columns of oil temperature and start time, and stores the start time of knock feedback control for each oil temperature. The unit of the value shown in the oil temperature column is ° C., and the unit of the value shown in the start time column is second. The oil temperature table 42 is constructed in a storage device such as the ROM 16 shown in FIG.

  The CPU 11 calculates a start time for an oil temperature of the engine with reference to the oil temperature table 42. The method for calculating the start time with respect to the oil temperature is the same as the method for calculating the start time of the water temperature described with reference to FIG. 5, and detailed description thereof is omitted.

  FIG. 7 is a table showing the relationship of the feedback control start time with respect to the intake air temperature. As shown in the figure, the intake air temperature table 43 has columns of intake air temperature and start time, and stores the start time of knock feedback control for each intake air temperature. The unit of the value shown in the intake air temperature column is ° C., and the unit of the value shown in the start time column is second. The intake air temperature table 43 is constructed in a storage device such as the ROM 16 shown in FIG.

  The CPU 11 calculates a start time for an intake air temperature of the engine with reference to the intake air temperature table 43. Note that the calculation method of the start time with respect to the intake air temperature is the same as the calculation method of the start time of the water temperature described in FIG. 5, and detailed description thereof is omitted.

  As described above, the CPU 11 acquires the engine water temperature, the oil temperature, and the intake air temperature from each sensor when starting the engine, and calculates the start time of the knocking feedback control for the acquired water temperature, oil temperature, and intake air temperature.

Next, the operation of the CPU 11 will be described using a flowchart.
FIG. 8 is a flowchart showing a process for calculating the feedback control start time. The CPU 11 executes processing according to the following steps.

  In step S1, the CPU 11 determines whether the starter has been switched from OFF to ON in order to take in the water temperature, oil temperature, and intake air temperature of the engine at the time of starting the engine. When the starter is switched from off to on, the process proceeds to step S2. If the starter is not switched from off to on, the process proceeds to step S7.

In step S <b> 2, the CPU 11 acquires the engine water temperature, oil temperature, and intake air temperature from the water temperature sensor 22, the oil temperature sensor 23, and the intake air temperature sensor 24.
In step S <b> 3, the CPU 11 refers to the water temperature table 41 and calculates the knocking feedback control (F / B) start time a for the water temperature acquired in step S <b> 2. In step S4, the CPU 11 refers to the oil temperature table 42 and calculates the start time b of knocking feedback control with respect to the oil temperature acquired in step S2. In step S5, the CPU 11 refers to the intake air temperature table 43 and calculates a start time c of knocking feedback control with respect to the intake air temperature acquired in step S2. In step S6, the CPU 11 calculates the maximum value d of the start times a to c calculated in steps S3 to S5.

  In step S7, the CPU 11 determines whether the maximum value d calculated in step S6 has elapsed after the engine is started. When the time elapses the maximum value d, the CPU 11 proceeds to step S8. If the time is less than the maximum value d, the process of the flowchart is terminated, and the process of the flowchart is repeated from the start at the next interruption.

  In step S8, the CPU 11 starts knocking feedback control. That is, if knocking does not occur as a result of knocking determination, the ignition timing of the spark plug 32 is advanced, and if knocking occurs, knock feedback control is started so as to retard the ignition timing of the spark plug 32. To do.

Next, the operation of the CPU 11 will be described using a control chart.
FIG. 9 is a diagram illustrating a control chart for calculating the feedback control start time. The waveform (a) of the figure shows the starter on / off timing. FIG. 4B shows a waveform indicating timing for counting the start time of knocking feedback control after the starter is turned on. (C) in the figure shows a background waveform. FIG. 4D shows a count value for starting knocking feedback control calculated based on the water temperature, the oil temperature, and the intake air temperature. (E) in the figure shows a counter value for counting time.

  As shown by a dotted line C1 in the figure, when the starter is switched from OFF to ON, the CPU 11 starts calculating the background. Since the background is an average of the peak values, it gradually converges to the peak value as shown in FIG. Further, the CPU 11 acquires the water temperature, oil temperature, and intake air temperature of the engine from each sensor, and refers to the water temperature table 41, the oil temperature table 42, and the intake air temperature table 43, and acquires the acquired water temperature, oil temperature, and intake air temperature. The start time (count value) of knocking feedback control with respect to the temperature is calculated. The count value for starting the feedback control of knocking with respect to the water temperature, the oil temperature, and the intake air temperature has a relationship of water temperature> oil temperature> intake air temperature as shown in FIG. Suppose that

  After calculating the count value for starting knocking feedback control, the CPU 11 starts counting the time for starting knocking feedback control as shown in FIG. Then, as shown in (e) of the figure, the counter value for counting time starts counting up from the timing of the dotted line C2.

  It is assumed that the counter value is counted up and reaches a count value for starting knocking feedback control based on the intake air temperature as indicated by an arrow C3. However, in the example of FIG. 7, the count value of the intake air temperature is not the maximum value of the count value for starting the knocking feedback control, and thus the CPU 11 does not start the knocking feedback control.

  It is assumed that the counter value is further counted up and reaches a count value for starting knocking feedback control based on the oil temperature as indicated by an arrow C4. However, in the example of FIG. 6, the count value of the oil temperature is not the maximum value of the count value for starting the knocking feedback control, and thus the CPU 11 does not start the knocking feedback control.

  Assume that the counter value is further counted up and reaches a count value for starting knocking feedback control based on the water temperature as indicated by an arrow C5. In the example of FIG. 5, the count value of the water temperature is the maximum value of the count value for starting the knocking feedback control, and thus the CPU 11 starts the knocking feedback control. As indicated by the dotted line C6, knocking feedback control is started after the background has converged to the peak value. In this way, by starting the feedback control of knocking with the maximum start time of the start time calculated based on the water temperature, oil temperature, and intake air temperature, for example, several convergence times when the background has not converged Even if calculated, it is possible to safely change the knocking feedback control start time and widen the control range.

  Thus, the water temperature, oil temperature, and intake air temperature for determining the convergence time at which the background will converge to the peak value when the engine is started are acquired, and based on the acquired water temperature, oil temperature, and intake air temperature. The background convergence time was calculated. Thus, the knocking control start time can be appropriately changed so as not to make an erroneous determination of knocking, and the knocking control range can be widened.

Further, since the knocking control start time is changed so as not to make an erroneous determination of knocking after the engine is started, it is possible to prevent an erroneous retardation of the engine.
Further, by using the maximum value of the convergence time obtained from the water temperature, the oil temperature, and the intake air temperature, it is possible to start the knocking feedback process more safely and prevent an erroneous delay angle.

  In the above, the feedback control of knocking is started at the maximum value of the convergence time based on the parameters of the water temperature, the oil temperature, and the intake air temperature. However, at the convergence time based on one parameter, or one or more The knocking feedback control may be started at the maximum value of the convergence time based on the parameters. For example, only the convergence time based on the water temperature may be calculated to start knocking feedback control, or only the convergence time based on the water temperature and oil temperature may be calculated to start knocking feedback control.

  Next, a knock detection device according to a second embodiment will be described in detail with reference to the drawings. In the second embodiment, the number of samples of the peak value necessary to converge to an appropriate background is calculated based on the peak value after engine start, and the peak value is obtained after obtaining the calculated number of samples. , Start knocking feedback control.

  Since the background is obtained by averaging the peak values as shown in the equation (1), when the engine is started, it does not converge to an appropriate value until the number of samples of the predetermined peak value is obtained. The number of peak values that the background converges to an appropriate value depends on the size of the peak value. If the difference between the background and the peak value is large, a large number of peak values that converge to the appropriate background are required. And Also, the number of samples of the peak value at which the background converges to an appropriate value varies depending on the annealing rate of the peak value (the reciprocal of the annealing value). Therefore, the CPU 11 shown in FIG. 2 calculates the number of samples of the peak value necessary to calculate an appropriate background, acquires the calculated peak number of the peak value, and then starts knocking feedback control. . For example, the CPU 11 sets a value obtained by dividing the peak value acquired for the first time after engine startup by the smoothing rate as the number of samples for starting knocking feedback.

  The relationship between the number of samples of the peak value and the engine speed will be described. The time for which the peak value is equal to the number of samples is proportional to the engine speed. If the engine speed is high, the time for aligning the peak number of samples is faster, and if the engine speed is low, the time for aligning the peak value samples is delayed.

  FIG. 10 is a diagram showing the background and the engine speed. The peak value and the background are shown in FIG. The engine speed is shown in (b) of the figure. The peak value is sampled in proportion to the engine speed. The CPU 11 calculates the number of samples of the peak value necessary for calculating the background, and starts knocking feedback control as soon as the engine speed is high, and starts knocking feedback control as late as the engine speed is low. It will be.

Next, the operation of the CPU 11 will be described using a flowchart.
FIG. 11 is a flowchart showing processing for calculating the number of samples of peak values for starting feedback control. CPU11 performs the process according to the following steps for every predetermined period.

  In step S11, the CPU 11 determines whether the starter has been switched from OFF to ON in order to initialize variables α and β described below when the engine is started. When the starter is switched from off to on, the process proceeds to step S12. If the starter is not switched from off to on, the process proceeds to step S14.

  In step S12, the CPU 11 initializes a variable α for counting the number of samples of the peak value, for example, to a minimum value of 0. In step S13, the CPU 11 initializes, for example, a variable β indicating the number of samples for starting the knocking feedback process to a maximum value of 0xFFFF.

  In step S <b> 14, the CPU 11 determines whether the knocking feedback process is in the gate open state (knocking observation period). That is, it is determined whether the gate control signal described in FIG. 2 is output to the peak hold amplifier 13. If the gate is open, the process proceeds to step S15. If the gate is not open, the process proceeds to step S20.

  In step S15, the CPU 11 updates the peak value. That is, a new peak value is acquired from the peak hold amplifier 13. In step S16, the CPU 11 updates the background with the acquired peak value. In step S17, the CPU 11 adds 1 to the variable α.

  In step S18, the CPU 11 determines whether or not the processing in steps S15 to S17 is the first time. If it is the first time, the process proceeds to step S19. If it is not the first time, the process proceeds to step S20.

  In step S19, the CPU 11 calculates a variable β indicating the number of samples for starting the knocking feedback control. The variable β is expressed by the following equation (3). The annealing rate in equation (3) is the reciprocal of the annealing value.

β = peak value / annealing rate (3)
That is, the number of samples for starting knocking feedback control is proportional to the peak value. The larger the peak value, the larger the number of samples for starting knocking feedback control. The number of samples for starting knocking feedback control is inversely proportional to the annealing rate. This is because if the annealing rate is small, a large number of samples are required to converge to the background peak value.

  In step S20, the CPU 11 determines whether or not the variable α for counting the number of samples of the peak value is equal to or larger than the variable β that is the number of samples for starting knocking feedback control. If the variable α is greater than or equal to the variable β, the process proceeds to step S21. If the variable α is smaller than the variable β, the process of the flowchart of FIG. 11 is terminated, and the process of the flowchart is repeated from the start at the next interruption.

In step S21, the CPU 11 starts knocking feedback control.
In this way, the number of samples required for the peak value for calculating the background is calculated based on the magnitude of the peak value, and after starting the engine, the peak value is obtained for the calculated number of samples, and then knocking feedback is performed. Control was started. Thus, the knocking control start time can be appropriately changed so as not to make an erroneous determination of knocking, and the knocking control range can be widened.

Moreover, since the number of samples of the peak value is changed so as not to make an erroneous determination of knocking after the engine is started, it is possible to prevent erroneous retardation of the engine.
Note that the first embodiment and the second embodiment can be combined. For example, as described in the second embodiment, the number of samples for starting knocking feedback control is calculated. Then, after obtaining the number of samples for which the peak value has been calculated, the start time based on the water temperature, the oil temperature, and the intake air temperature described in the first embodiment is calculated, and after the calculated start time, knocking feedback control is performed. Start. Specifically, when the variable α becomes equal to or larger than the variable β in step S20 of the flowchart shown in FIG. 11, the processing after step S2 of the flowchart shown in FIG. 8 is executed.

  Next, a knock detection device according to a third embodiment will be described in detail with reference to the drawings. While the starter is on, the engine is cranked by the starter motor, so that noise is likely to occur in the data, and there is a risk of erroneous determination regarding knock determination. Therefore, in the third embodiment, when the starter is switched from on to off after the engine is started, counting of the time for starting knocking feedback control is started, and knocking feedback control is always turned off. To be done after.

  FIG. 12 is a diagram illustrating an outline of the knock detection device. In FIG. 12, the internal combustion engine starting means 3 and the time measuring starting means 1f are shown in FIG. 12, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The internal combustion engine starting means 3 shown in the figure is an electric motor (starter) that performs cranking for starting the internal combustion engine 2. The internal combustion engine starting means 3 outputs a starter on / off signal to the time measuring starting means 1f.

  A signal indicating whether or not the internal combustion engine 2 has been started and an on / off signal for the internal combustion engine starting means 3 are input to the timing start means 1f. When a signal indicating that the engine is started from the internal combustion engine 2 is input and an off signal is input from the internal combustion engine start unit 3, the time measurement starting unit 1f allows the knock determination control unit 1e to measure a predetermined time. That is, the time measuring start means 1f causes the knock determination control means 1e to start measuring a predetermined time after the internal combustion engine 2 is started by the internal combustion engine starting means 3 and the internal combustion engine starting means 3 is turned off. The knock determination control means 1e starts measuring a predetermined time according to the temperature of the internal combustion engine 2 by the control of the time measurement start means 1f, and cancels the operation of the knock determination means 1c when the predetermined time elapses. To do.

  As described above, the predetermined time for starting the knocking feedback control is started after the internal combustion engine 2 is started and the internal combustion engine starting means 3 is turned off. Thereby, since the feedback control of knocking is performed after the internal combustion engine starting means 3 is turned off, the influence of noise due to cranking of the internal combustion engine starting means 3 can be reduced, and erroneous determination regarding knock determination is suppressed. be able to.

Next, a block configuration diagram of the knock detection device will be described.
FIG. 13 is a block diagram of the knock detection device. In FIG. 13, an engine 33 and a starter 34 are shown in FIG. Further, the CPU 11a of the knock detection device 10a has I / O (Input / Output) 1 and 2. 13, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  The starter 34 is turned on / off by a user's key operation, for example, and starts the engine 33. The starter 34 outputs an on / off signal indicating the on / off state to the I / O 1 of the CPU 11a. Further, when the engine 33 is started, it outputs a signal to that effect to the I / O 2 of the CPU 11a.

  When a signal indicating that the engine has started is input to I / O2 and an off signal of the starter 34 is input to I / O1, the CPU 11a starts measuring time for starting knocking feedback control.

Next, the operation of the CPU 11a will be described using a control chart.
FIG. 14 is a diagram illustrating a control chart for calculating the feedback control start time. FIG. 4A shows a waveform indicating the timing at which knock determination is performed. (B) of the figure shows a waveform showing the on / off timing of the starter. FIG. 2C shows a waveform showing the engine start timing. The waveform of the background is shown in FIG. (E) of the figure shows a count value for starting knocking feedback control calculated based on the water temperature, the oil temperature, and the intake air temperature. (F) in the figure shows a counter value for counting time. The third embodiment is different from the first embodiment in that counting of the time for starting knocking feedback control is started at the timing when the starter is switched from on to off after the engine is started. Other configurations and functions are the same as those in the first embodiment, and a detailed description thereof will be omitted.

  As shown by the dotted line D1 in the figure, when the starter is switched from OFF to ON, the CPU 11a starts calculating the background. Since the background is an average of the peak values, it gradually converges to the peak value as the engine rotates, as shown in FIG. Further, the CPU 11a obtains the engine water temperature, the oil temperature, and the intake air temperature from each sensor, and refers to the water temperature table 41, the oil temperature table 42, and the intake air temperature table 43 as shown in FIG. A time (count value) for starting the feedback control of knocking is calculated.

  When the engine is started as shown in (c) of the figure and the starter is turned off as shown in (b) of the figure, the CPU 11a starts the knocking feedback control as shown in (f) of the figure. Counting is started (dotted line D2 in the figure).

  When the counter value is counted up and reaches a count value for starting knocking feedback control as indicated by an arrow D3, the CPU 11a starts knocking feedback control as indicated by an arrow D4. Since the ignition timing is mechanically controlled before the engine start is completed, it is not necessary to reflect the knock determination result in the ignition timing control.

Next, the operation of the CPU 11a will be described using a flowchart.
FIG. 15 is a flowchart showing a process for calculating the feedback control start time. In FIG. 15, the same processes as those of FIG.

In steps S1 to S6, as described with reference to FIG. 8, the CPU 11a calculates a time (maximum value d) for starting the knocking feedback control.
In step S61a, the CPU 11a determines whether or not the engine 33 has been started. If the engine 33 does not start, the process ends. If the engine 33 starts, the process proceeds to step S62a.

  In step S62a, the CPU 11a determines whether or not the starter 34 is turned off. When the starter 34 is turned off, the process proceeds to step S63a. If the starter 34 is on, the process ends.

  In step S63a, the CPU 11a starts measuring time for starting feedback control. In step S7, as described with reference to FIG. 8, the CPU 11a determines whether the maximum value d has elapsed, and when the maximum value d has elapsed, the process proceeds to step S8. In step S8, the CPU 11a starts knocking feedback control.

  Thus, the time measurement for starting the feedback control is started after the starter is switched from on to off after the engine is started. Thereby, since the knock determination is performed after the starter is turned off, it is possible to reduce the influence of noise due to the cranking of the motor when the starter is on, and it is possible to suppress erroneous determination regarding the knock determination.

  Next, a knock detection device according to a fourth embodiment will be described in detail with reference to the drawings. Since the engine is cranked by the starter motor while the starter is on, noise is likely to occur in the knock signal, and the background value may become abnormal. Therefore, in the fourth embodiment, after the engine is started, the background calculation is started when the starter is switched from on to off, and the counting of the time for starting the knocking feedback control is started. To.

  FIG. 16 is a diagram showing an outline of the knock detection device. In FIG. 16, the function of the background calculation means 1g is partially different from that in FIG. Also shown is an internal combustion engine starting means 3 that performs cranking for starting the internal combustion engine 2. 16, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The background calculation means 1g shown in the figure receives a signal indicating whether or not the engine has been started from the internal combustion engine 2 and an on / off signal from the internal combustion engine start means 3. When a signal indicating that the engine has been started from the internal combustion engine 2 is input and an off signal is input from the internal combustion engine starting means 3, the background calculation unit 1g starts calculating the background. That is, the background calculation means 1g starts the calculation of the background after the internal combustion engine 2 is started by the internal combustion engine start means 3 and the internal combustion engine start means 3 is turned off. The knock determination control unit 1e prohibits the operation of the knock determination unit 1c until a predetermined time corresponding to the temperature of the internal combustion engine 2 acquired by the temperature acquisition unit 1d has elapsed.

  Thus, the background calculation is started after the internal combustion engine 2 is started and after the internal combustion engine starting means 3 is switched from on to off. Thereby, the influence of the background noise by the cranking of the internal combustion engine starting means 3 can be reduced, and the erroneous determination about the knock determination can be suppressed.

  Next, the operation of the knock detection apparatus according to the fourth embodiment will be described using a control chart. The block diagram in the fourth embodiment is the same as that in FIG. However, the difference is that the CPU 11a calculates the background when an off signal is output from the starter 34 after the engine 33 is started.

  FIG. 17 is a diagram illustrating a control chart for calculating the feedback control start time. FIG. 4A shows a waveform indicating the timing at which knock determination is performed. (B) of the figure shows a waveform showing the on / off timing of the starter. FIG. 2C shows a waveform showing the engine start timing. The waveform of the background is shown in FIG. (E) of the figure shows a count value for starting knocking feedback control calculated based on the water temperature, the oil temperature, and the intake air temperature. (F) in the figure shows a counter value for counting time. In the fourth embodiment, after the engine is started, the background calculation is started at the timing when the starter is switched from on to off, and the counting of the time for starting the knocking feedback control is started. This is different from the third embodiment. Other configurations and functions are the same as those of the third embodiment, and a detailed description thereof will be omitted.

  When the starter is turned on, the CPU 11a acquires the engine water temperature, the oil temperature, and the intake air temperature from each sensor, and refers to the water temperature table 41, the oil temperature table 42, and the intake air temperature table 43 (e in FIG. The time (count value) for starting the feedback control of knocking as shown in FIG.

  When the engine is started and the starter is turned off as shown in (b) and (c) of the figure, the CPU 11a starts calculating the background as shown in (d) of the figure (dotted line E1 in the figure). . Since the background is an average of the peak values, it gradually converges to the peak value as shown in FIG. When the engine is started and the starter is turned off as shown in (b) and (c) of the figure, the CPU 11a counts for starting knocking feedback control as shown in (f) of the figure. Is counted up (dotted line E1 in the figure).

  When the counter value is counted up and reaches a count value for starting knocking feedback control as indicated by an arrow E2, the CPU 11a starts knocking feedback control as indicated by E3 in the figure.

Next, the operation of the CPU 11a will be described using a flowchart.
FIG. 18 is a flowchart showing a process for calculating the feedback control start time. 18, the same processes as those in FIG. 8 are denoted by the same reference numerals, and the description thereof is omitted.

In steps S1 to S6, as described with reference to FIG. 8, the CPU 11a calculates a time (maximum value d) for starting the knocking feedback control.
In step S61b, the CPU 11a determines whether or not the engine 33 has been started. If the engine 33 does not start, the process ends. If the engine 33 starts, the process proceeds to step S62b.

  In step S62b, the CPU 11a determines whether or not the starter 34 is turned off. When the starter 34 is turned off, the process proceeds to step S63b. If the starter 34 is on, the process ends.

  In step S63b, the CPU 11a starts calculating the background. In step S64b, the CPU 11a starts measuring time for starting feedback control. In step S7, as described with reference to FIG. 8, the CPU 11a determines whether the maximum value d has elapsed, and when the maximum value d has elapsed, the process proceeds to step S8. In step S8, the CPU 11a starts knocking feedback control.

  As described above, the background calculation and the time counting for starting the feedback control are started after the starter is switched from on to off after the engine is started. As a result, the influence of background noise due to the cranking of the motor when the starter is on can be reduced, and erroneous determination regarding knock determination can be suppressed.

  Next, a knock detection device according to a fifth embodiment will be described in detail with reference to the drawings. In the fifth embodiment, the knock determination result is not used for controlling the ignition timing of the engine until a predetermined time corresponding to the engine temperature has elapsed.

  FIG. 19 is a diagram showing an outline of the knock detection device. In FIG. 19, the ignition timing control means 1h is shown with respect to FIG. 19, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  As described with reference to FIG. 1, knock determination means 1c performs knock determination based on the peak value and the background, and controls the ignition timing of internal combustion engine 2 to advance and retard according to the determination result. The ignition timing control means 1h advances and retards the ignition timing of the internal combustion engine 2 in accordance with the advance and retard control of the knock determination means 1c.

  The knock determination control means 1e prohibits the operation of the knock determination means 1c until the time corresponding to the temperature of the internal combustion engine 2 elapses as described in FIG. That is, the knock determination by the knock determination means 1c is not reflected in the ignition timing control until a predetermined time corresponding to the temperature of the internal combustion engine 2 has elapsed.

  Next, operation | movement of the knock detection apparatus based on 5th Embodiment is demonstrated using a flowchart. The block diagram in the fifth embodiment is the same as that in FIG. However, the CPU 11a does not reflect the knock determination result in the ignition timing control until a predetermined time corresponding to the temperature of the engine 33 has elapsed.

FIG. 20 is a diagram illustrating a control chart for calculating the feedback control start time. In FIG. 20, the same processes as those in FIG. 8 are denoted by the same reference numerals, and the description thereof is omitted.
In steps S1 to S6, as described with reference to FIG. 8, the CPU 11a calculates a time (maximum value d) for starting the knocking feedback control.

  In step S61c, the CPU 11a determines whether or not the engine 33 has been started. If the engine 33 does not start, the process ends. If the engine 33 starts, the process proceeds to step S62c.

  In step S62c, the CPU 11a determines whether or not the starter 34 is turned off. When the starter 34 is turned off, the process proceeds to step S63c. If the starter 34 is on, the process ends. In step S63c, the CPU 11a does not reflect the knock determination result in the ignition timing control.

  In step S64c, the CPU 11a starts measuring time for starting feedback control. In step S7, as described with reference to FIG. 8, the CPU 11a determines whether the maximum value d has elapsed, and when the maximum value d has elapsed, the process proceeds to step S8. In step S8, the CPU 11a reflects the result of the knock determination in the ignition timing control.

  As described above, the knocking control range can also be widened by not reflecting the knock determination result in the ignition timing control until a predetermined time corresponding to the temperature of the engine 33 has elapsed.

It is the figure which showed the outline | summary of the knock detection apparatus. It is a block block diagram of the knock detection apparatus which concerns on 1st Embodiment. It is a wave form diagram for demonstrating knock determination. It is a figure explaining the convergence time of a background. It is the table which showed the relationship of the feedback control start time with respect to water temperature. It is the table which showed the relationship of the feedback control start time with respect to oil temperature. It is the table which showed the relationship of the feedback control start time with respect to intake temperature. It is the flowchart which showed the process which calculates feedback control start time. It is the figure which showed the control chart which calculates feedback control start time. It is the figure which showed the background and the engine speed. It is the flowchart which showed the process which calculates the sample number of the peak value for starting feedback control. It is a figure which shows the outline | summary of a knock detection apparatus. It is a block block diagram of a knock detection apparatus. It is the figure which showed the control chart which calculates feedback control start time. It is the flowchart which showed the process which calculates feedback control start time. It is a figure which shows the outline | summary of a knock detection apparatus. It is the figure which showed the control chart which calculates feedback control start time. It is the flowchart which showed the process which calculates feedback control start time. It is a figure which shows the outline | summary of a knock detection apparatus. It is the figure which showed the control chart which calculates feedback control start time. It is a figure explaining the convergence of the background at the time of engine starting.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Knock detection apparatus 1a Peak value acquisition means 1b Background calculation means 1c Knock determination means 1d Temperature acquisition means 1e Knock determination control means 2 Internal combustion engine

Claims (7)

A knock detection device for detecting knock of an internal combustion engine,
Threshold calculation means for calculating a threshold for knock determination based on a plurality of knock signals of the internal combustion engine;
Knock determination means for performing the knock determination based on the threshold;
Knock determination control means for prohibiting the knock determination based on the threshold until a predetermined time corresponding to the temperature at the start of the internal combustion engine elapses when the internal combustion engine is started ;
A knock detection device comprising:   2. The knock detection device according to claim 1, wherein the predetermined time is determined according to a temperature of the internal combustion engine and a magnitude of the knock signal detected after the internal combustion engine is started. The threshold value is calculated based on the knock signal detected during a predetermined crank period of the internal combustion engine,
The knock detection device according to claim 1, wherein the predetermined time is obtained according to a temperature of the internal combustion engine and a magnitude of the knock signal detected during a predetermined crank period after the internal combustion engine is started.   2. The knock detection device according to claim 1, further comprising a timing start means for starting timing of the predetermined time after the start of the internal combustion engine and after the starter signal is turned off.   The knock detection device according to claim 1, wherein the calculation of the threshold value is started after the start of the internal combustion engine and the starter signal is turned off.   The knock determination control unit according to claim 1 or 5, wherein the knock determination control means does not use the result of the knock determination based on the threshold value for controlling the ignition timing of the engine until the predetermined time has elapsed. Detection device. A knock detection device for detecting knock of an internal combustion engine,
Threshold calculation means for calculating a threshold for knock determination based on a plurality of knock signals of the internal combustion engine;
Knock determination means for performing the knock determination based on the threshold;
A knock determination control means for prohibiting the knock determination based on the threshold value until a predetermined time corresponding to the magnitude of the knock signal detected at the start of the internal combustion engine has elapsed when the internal combustion engine is started;
A knock detection device comprising:

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