Detecting device of intake pipe pressure

Description: TECHNICAL FIELD [Detailed description of the invention]

[Industrial application field] The present invention relates to an intake pipe pressure detecting device for detecting the intake pipe pressure of an internal combustion engine, and in particular, the intake pipe pressure for detecting the intake pipe pressure of a so-called independent intake type internal combustion engine in which the internal combustion engine includes a throttle valve in the intake pipe for each cylinder. Regarding the detection device.

[Conventional technology] Conventionally, the amount of air sucked into the internal combustion engine is detected, the optimum amount of fuel that matches the amount of air is supplied to operate the internal combustion engine at the desired air-fuel ratio, and the optimum ignition according to the amount of air sucked The combustion timing is controlled by the timing. The intake air amount of a multi-cylinder internal combustion engine is usually calculated after detecting the intake pipe pressure using a pressure sensor as an average value of all cylinders, or is detected by an air flow meter. However, in recent years, a so-called independent intake type internal combustion engine in which a throttle valve is provided for each cylinder of the internal combustion engine in order to further improve the operating performance of the internal combustion engine and improve the response such as acceleration response has been proposed. The control technology for the internal combustion engine has been researched and developed. That is, since the independent intake type internal combustion engine has a throttle valve for each cylinder, not only the responsiveness is improved, but also the pressure interference between the cylinders is eliminated and the internal combustion engine can be operated more efficiently. On the other hand, in order to detect the intake air amount of each cylinder, it is necessary to provide an air flow meter, a pressure sensor, etc. for each cylinder, and the structure is complicated. Therefore, as a device for detecting the intake air amount for controlling the independent intake type internal combustion engine, a simple air flow meter system having a structure in which an air flow meter is provided at a place where each intake cylinder is gathered upstream of the throttle valve is used. As a method for detecting the intake pipe pressure, which is the mainstream, a new communication pipe leading to each cylinder is provided to detect the averaged pressure.

[Problems that the invention tries to solve] However, the above technology also has the following problems, and cannot be said to be sufficient yet. That is, the greatest advantage of the independent intake type internal combustion engine is the improvement of response, but the one provided with an air flow meter at the gathering part of each intake pipe has the above advantage because the air flow meter acts as a resistance of the intake air. Work to reduce. Therefore, in order to control the independently intake type internal combustion engine, it is a more preferable technique to accurately detect the air pipe pressure. However, in the conventional technique in which a communication pipe is provided in each cylinder to detect the intake air pressure, pressure interference between the cylinders occurs as a new problem through the communication pipe, and the structure is not sufficient. There was also a problem in terms of cost due to the complexity. The present invention has been made to solve the above problems, and even in an independent intake type internal combustion engine, the structure is simple and the intake pipe pressure of the internal combustion engine is accurate while taking advantage of the characteristics of the independent intake type. It is an object of the present invention to provide an excellent intake pipe pressure detecting device capable of detecting.

[Means to solve the problem] The configuration of the intake pipe pressure detecting device according to the first invention is as illustrated in FIG. 1 (A). In the intake pipe pressure detection device that detects the intake pipe pressure of an internal combustion engine having a throttle valve for each intake pipe of each cylinder. A pressure detecting means for detecting the intake pipe pressure on the downstream side of each throttle valve of a cylinder having a number smaller than the number of cylinders of the internal combustion engine in synchronization with the crank angle of the internal combustion engine. Throttle opening detection means for detecting the opening degree of the throttle valve at a frequency higher than the pressure detection frequency of the pressure detecting means, and Correction for setting a correction reference value as a reference for correction of the intake pipe pressure based on the opening degree of the throttle valve detected at a timing close to the timing at which the intake pipe pressure is detected by the pressure detecting means. Reference value setting means and The intake pipe pressure is corrected based on the deviation between the value corresponding to the opening degree of the throttle valve and the correction reference value detected at a frequency higher than the pressure detection frequency of the pressure detecting means, and the intake pipe of the internal combustion engine is corrected. A correction means to obtain a value according to the pressure, It is characterized by having. Further, the configuration of the intake pipe pressure detecting device according to the second invention is as illustrated in FIG. 1 (B). In the intake pipe pressure detection device that detects the intake pipe pressure of an internal combustion engine having a throttle valve for each intake pipe of each cylinder. A pressure detecting means for detecting the intake pipe pressure on the downstream side of each throttle valve of a cylinder having a number smaller than the number of cylinders of the internal combustion engine in synchronization with the crank angle of the internal combustion engine. A rotation speed detecting means for detecting the rotation speed of the internal combustion engine, and Throttle opening detection means for detecting the opening degree of the throttle valve at a frequency higher than the pressure detection frequency of the pressure detecting means, and A correction value setting means for setting a correction value based on the opening degree of the throttle valve and the rotation speed, and The correction value set based on the opening degree of the throttle valve and the rotation speed detected at a timing close to the timing at which the intake pipe pressure is detected by the pressure detecting means is used to correct the intake pipe pressure. Correction reference value setting means to be set as a correction reference value that serves as a reference for A correction means for correcting the intake pipe pressure based on the deviation between the correction value and the correction reference value to obtain a value corresponding to the intake pipe pressure of the internal combustion engine. It is characterized by having.

[Action, etc.] In the first invention, the intake pipe pressure of some cylinders is detected by the pressure detecting means in synchronization with the crank angle, and the throttle opening detection means detects the opening of the throttle valve at a frequency higher than the detection frequency. Then, the correction reference value setting means is used as a reference for correcting the intake pipe pressure based on the opening degree of the throttle valve detected at the timing closest to the timing at which the intake pipe pressure is detected by the pressure detecting means. Set the reference value. Further, the correction means corrects the intake pipe pressure based on the deviation between the value corresponding to the opening degree of the throttle valve detected more frequently than the pressure detection frequency of the pressure detection means and the correction reference value, and intakes the internal combustion engine. Obtain a value according to the tube pressure. Further, in the second invention, the rotation speed detecting means further detects the rotation speed of the internal combustion engine, and the correction value setting means sets the correction value based on the opening degree and the rotation speed of the throttle valve. The correction reference value setting means sets the correction value of the intake pipe pressure based on the throttle valve opening and the number of revolutions detected at a timing close to the timing at which the intake pipe pressure is detected by the pressure detecting means. Set as a correction reference value that serves as a reference for correction. Then, the correction means corrects the intake pipe pressure based on the deviation between the correction value and the correction reference value, and obtains a value corresponding to the intake pipe pressure of the internal combustion engine. In the second invention, since the rotation speed is taken into consideration in the correction value, a value corresponding to the intake pipe pressure of the internal combustion engine is further obtained. Here, the pressure detecting means in the first and second inventions detects the intake pipe pressure of a certain cylinder in synchronization with the crank angle of the internal combustion engine. Synchronizing with the crank angle is to accurately detect the time when the cylinder for which the intake pipe pressure is to be detected is in the intake stroke. Therefore, for example, a conventionally used intake pipe pressure sensor may be used to capture the sensor output at a predetermined crank angle. Further, the rotation speed detecting means in the second invention is easily configured, for example, by calculating the number of outputs per unit time of the crank angle detecting means conventionally provided in the internal combustion engine. Further, the predetermined crank angle of the pressure detecting means is also easily detected by the rotation speed detecting means and the cylinder discrimination sensor conventionally provided in the internal combustion engine. Further, in the first and second inventions, the throttle opening degree detecting means detects the opening degree of the throttle valve provided in the intake pipe of each cylinder, and all the throttle valves are independently controlled, and the opening degree is controlled. If it is independent, the opening degree of each throttle valve may be detected, and if all throttle valves are interlocked, only one throttle opening degree may be detected. The detection frequency of the throttle opening degree is higher than the detection frequency of the intake pipe pressure by the pressure detecting means described above. Therefore, for example, when the intake pipe pressure of a certain cylinder is detected for each crank angle of 720 ° CA of the internal combustion engine, and N cylinders are provided with pressure detecting means. , The throttle opening detection means is, for example, 720. The opening of the throttle valve is detected by synchronizing the crank angle for each crank angle smaller than CA / N, or the opening of the throttle valve is set in a cycle shorter than the time required to rotate 720 CA / N at the crank angle. It should be detected. The value corresponding to the throttle valve opening degree in the first invention means a value obtained by converting the value of the throttle valve opening degree as necessary so that it can be calculated with the correction reference value. That is, in order to calculate the deviation from the correction reference value, the value of the throttle valve opening itself obtained by measurement may be inconvenient due to a unit problem or the like. Therefore, it is common knowledge among those skilled in the art that some adjustment is required between the throttle valve opening value and the correction reference value so that the deviation can be calculated. The adjusted value of the throttle valve opening degree is expressed as a value corresponding to the opening degree of the throttle valve. Of course, if the measured throttle valve opening is a value that can be calculated from the beginning without any adjustment, the measured throttle valve opening value itself is the throttle valve. It corresponds to the value corresponding to the opening degree. Further, the first and the correction means of the present invention correct the intake pipe pressure based on the deviation between the value corresponding to the opening degree of the throttle valve and the correction reference value, and obtain a value corresponding to the intake pipe pressure of the internal combustion engine. It is for getting. As described above, the pressure detecting means outputs information only in synchronization with the inspiratory stroke, but the frequency is once every 720 ° CA. Therefore, in the first invention, when the intake pipe pressure at an arbitrary time point is required, the intake pipe pressure actually measured by the pressure detecting means corresponds to the opening degree of the throttle valve detected by the throttle opening detection means. Correction is made based on the deviation between the value to be adjusted and the correction reference value, and a value corresponding to the intake pipe pressure is obtained in consideration of the change in the opening degree of the throttle valve by such correction. On the other hand, the correction means in the second invention corrects based on the deviation between the correction value and the correction reference value, but the correction value in this case is not only the opening degree of the throttle valve but also the rotation speed of the internal combustion engine. Is also taken into consideration. That is, when the intake pipe pressure cannot be directly measured by the pressure detecting means, the actual intake pipe pressure measured immediately before is corrected by considering the opening degree of the throttle valve and the rotation speed of the internal combustion engine. It is possible to obtain an accurate value according to the intake pipe pressure. The correction means in the first and second inventions are composed of a logical operation circuit centered on a microcomputer or a discrete operation circuit, and correction values and the like are calculated each time, or are searched from a map. either will do.

[Example] Hereinafter, an embodiment of the present invention will be described in detail in order to specifically explain the present invention. However, the present invention is not limited to the following embodiment, and includes all embodiments that are obvious to those skilled in the art. FIG. 2 is a schematic view of a control system of a 4-cylinder independent intake internal combustion engine equipped with the intake pipe pressure detection device of the embodiment. In the figure, 10 indicates a 4-cylinder engine, and the intake pipe 11 of each cylinder is connected to a throttle valve 12 linked to an accelerator pedal (not shown) and a fuel tank (not shown) to inject fuel toward the intake pipe. An injection valve 13 is provided. The cylinders are arranged in the order of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder from the upper part of the drawing. Further, the spark plug 14 provided for each cylinder is appropriately supplied with a high voltage by the distributor 15 to determine the ignition timing. Reference numeral 16 denotes a throttle opening sensor that detects the opening degree of the throttle valve 12, and outputs an analog output proportional to the opening degree of the throttle valve 12. In this embodiment, an intake pipe pressure sensor 17 including a pressure sensor for detecting the intake pipe pressure is provided on the downstream side of the throttle valve 12 of the intake pipe 11 of the first cylinder. Further, 18 represents a water temperature sensor that detects the cooling water temperature of the internal combustion engine 10, 19 represents an oxygen sensor that detects the oxygen concentration in the exhaust gas of the internal combustion engine 10, and 20 represents an intake air temperature sensor that detects the intake air temperature. The output of these various sensors and the operating state of various devices are centrally processed by the electronic control device 30. As shown in the figure, the electronic control device 30 is composed of a logical operation circuit 10 centered on a microcomputer, and operates by receiving electric power from a vehicle-mounted battery 21 via a key switch 22. 31 is the central part of the computer, which is a CPU that executes various operations, and performs processing according to the control program and map stored in ROM 32, which will be described later. 33 is RAM for temporary storage of data. 34 is the output from the various sensors mentioned above, the throttle opening sensor 16, the intake pipe pressure sensor 17, the water temperature sensor 18, the oxygen sensor 19, and the intake temperature sensor 20, the cylinder discrimination signal from the distributor 15, and the rotation angle of the crank angle. It is an input port that inputs the corresponding rotation angle signal, including an A / D converter, waveform meter, etc., and outputs necessary information to the CPU 31 as appropriate. Reference numeral 35 denotes an output port, which outputs the valve opening timing and time to the fuel injection valve 13 of each cylinder according to the calculation result of the CPU 31, and also outputs a signal for determining the ignition timing of the spark plug 14 to the distributor 15. There is. Each component of the electronic control device 30 is connected by a data and an address bus 36. FIGS. 3 (A), 3 (B) and 4 show a flowchart of the intake pipe pressure detection program stored in the ROM 32. FIGS. 3A and 3B show a flowchart of a routine for determining the timing of capturing the output of the sensor. In the figure (A), the timing of capturing the output of the intake pipe pressure sensor 17 is managed by a routine that is repeatedly executed by the CPU 31 in synchronization with the crank angle of the internal combustion engine 10. First, when the crank angle becomes a predetermined value and the CPU 31 enters the processing of this routine, it is determined in step 100 whether or not it is the timing to take in the output PS of the intake pipe pressure sensor 17. The intake timing of PS is as shown in the timing chart (A) of Fig. 5, when the crank angle with respect to the TDC of the first cylinder is taken as the horizontal axis, the intake pipe pressure sensor 17 takes in the intake of the first cylinder. It is the timing at which an output indicating the negative pressure status during the process is generated. Therefore, as is clear from the timing chart in Fig. 5 (A), the intake pipe pressure of the first cylinder shown by the solid line is arbitrary during the period (about 0 ° CA to 360 ° CA) in which the pressure is greatly depressed. At this point, in this embodiment, the capture of the output PS of the sensor is started at about 160 ° CA. If it is determined in this step 100 that the crank angle of the internal combustion engine 10 is about 160 ° CA, the A / D conversion process of the output of the intake pipe pressure sensor 17 is started in the next step 110, and the intake pipe pressure sensor A series of processing such as A / D conversion of the output of 17 at the input port 34 and temporarily storing the value PSAD (Fig. 5 (B)) in the buffer is started. If the crank angle is other than about 160 ° CA, this routine is terminated and other routines are executed without starting the process of step 110 as described above. FIG. 3B shows a routine for capturing the output (TA) of the throttle opening sensor 16 which is repeatedly processed by the CPU 31 every time a predetermined time elapses. First, when the processing of the CPU 31 shifts to this routine, it is determined in step 200 whether or not a predetermined time (T [ms]) has elapsed after the previous processing of this routine. Then, step 210 is processed only when it is determined that T [ms] has elapsed, and this routine is terminated otherwise. This step 210 controls the start of a series of processes for A / D converting the output TA of the throttle opening sensor 16 and storing the value (TAAD) at a predetermined address, and the intake of TAAD is started. .. FIG. 5 (D) is a timing chart for capturing the output of the throttle opening sensor 16. As shown in the figure, the value TAAD obtained by A / D converting TA is executed every predetermined cycle T [ms]. This predetermined period T [ms] is always smaller than the period during which the A / D conversion value PSAD of the intake pipe pressure is taken in, and TAAD is taken in at a frequency higher than the PSAD uptake frequency. Therefore, it is not limited to synchronizing with a short cycle T [ms] as in this embodiment, and the timing of TAAD may never be synchronized with a crank angle smaller than the crank angle of 720 ° CA, which is the cycle of PSAD. FIG. 4 shows the main routine of this embodiment, and calculates the intake pipe pressure PM of the internal combustion engine 10. This routine is repeatedly executed by the CPU 31 at predetermined time intervals. When CPU 31 enters the processing of this routine, A / D conversion of the output PS of the intake pipe pressure sensor 17 (a series of processing started in step 110 described above) is completed in step 300, and the latest PS value. It is judged whether or not it has been taken in. If it is determined in this step that the latest PS A / D conversion has not been completed, the process proceeds to step 330, which will be described later, and if the A / D conversion is completed, the next step 310 is processed. In step 310, the A / D conversion value PSAD of the output PS of the intake pipe pressure sensor 17 is calculated in the CPU 31. Then, the reference intake pipe pressure (the true intake pipe pressure when the output PS of the intake pipe pressure sensor 17 is taken in) is the basis for calculating the intake pipe pressure PM of the internal combustion engine 10 from this A / D conversion value PSAD. The PMB is calculated (step 320). That is, PMB is calculated every time the crank angle reaches 160 ° CA (Fig. 5 (C)). Subsequent steps 330 and 340 execute the same processing as in step 300 and step 310 described above, and the processing for taking in the throttle opening TA in step 210 in FIG. 3B is completed, and the latest TA value is obtained. Is obtained (step 330), and if it is not completed, step 380 described later is executed, and only when it is completed, the CPU 31 executes the calculation of the TA A / D conversion value TAAD. (Step 340). Then, the correction value PMTAi of the reference intake pipe pressure PMB is calculated from the value TAAD by the process of the next step 350 and stored in the RAM 33. In this case, the correction value PMTAi corresponds to a value corresponding to the opening degree of the throttle valve of the first invention. Both the above-mentioned PMB and PMTAi calculation in this step can be calculated by actually executing the calculation, or by preparing a map in ROM32 in advance to increase the execution speed and calculating by searching this map. Good. Further, in calculating PMTAi, PMTAi may be calculated from TA and NE in consideration of not only the throttle opening TA but also the rotation speed NE. Even if the throttle opening is the same, the intake pipe pressure changes depending on the number of revolutions, so if PMTAi is calculated from these two values, the correction value can be calculated with higher accuracy. In this case, PMTAi corresponds to the correction value of the second invention, and step 350 corresponds to the correction value setting means of the second invention. In the next step 360, it is determined whether or not the PMTAi calculated in step 350 is at the timing immediately before executing the PS A / D conversion. As shown in FIGS. 5 (B) and 5 (D), PSAD is calculated every 720 ° CA at the crank angle, TAAD is calculated every predetermined period T [ms], and TAAD is always calculated at a frequency of calculation. Is set higher than the calculation frequency of PSAD. Therefore, the TAAD calculation is always executed very close to the PSAD calculation timing (within a small time difference). Therefore, in this step, it is determined whether or not PMTAi is calculated by TAAD at the timing immediately before the PSAD timing. Then, only when this PMTAi is at the timing immediately before PSAD, the process as the correction reference value setting means is executed in step 370, the PMTAi value is set to the correction reference value PMTAB, and otherwise, the process proceeds to step 380. Proceed with. Figure 5 (D) shows the relationship between PMTAi and PMTAB. Since step 370 is executed immediately before a new reference intake pipe pressure PMB is obtained by executing step 320, ΔPMTA becomes zero from the execution timing of step 370 to the execution timing of step 320. However, as is clear from the change state of the PM value shown in FIG. 5 (E), the correction reference value PMTAB is rewritten in step 370 from the execution timing of step 370 to the execution timing of step 320. Use the previous correction reference value PMTAB. Then, after the execution of step 320, step 380 is executed using the new correction reference value PMTAB. Step 380 and step 390 are steps for executing the process as the correction means to calculate the intake pipe pressure PM, and calculate PM from the latest PMB value, PMTAB value, and PMTAi value by the following equation. .. PM = PMB + (PMTAi-PMTAB) That is, the PMB value is corrected by the value of (PMTAi-PMTAB) calculated in step 380. As described above, PMTAB was calculated immediately before the PMB was calculated, and the effect (PMTAB) of this throttle opening TA on the intake pipe pressure has already been reflected in the PMB value. However, when the throttle valve 12 is controlled to open and close from the time of this PMB calculation, the intake pipe pressure PM and the rotation speed NE naturally change, but this change in PM should be calculated up to the next predetermined crank angle (160 ° CA). I can't. Therefore, when information on the intake pipe pressure PM of the internal combustion engine 10 is required within the undetectable time of this PM, PMTAi and PMTAB calculated from the throttle opening TA or the throttle opening TA and the rotation speed NE at that time are used. Difference ΔPMTA, that is, how much the intake pipe pressure changes based on changes in throttle opening TA and rotation speed NE compared to the time when PMB was calculated, and by adding this value to PMB, the internal combustion engine 10 The intake pipe pressure PM (Fig. 5 (E)) is always calculated. The shaded area in FIG. 5 (D) represents the throttle opening TA or the correction width (ΔPMTA) of the intake pipe pressure based on the throttle opening TA and the rotation speed NE. As described above, in this embodiment, in steps 370 to 390, ΔPMTA corresponding to the change in the throttle opening TA and the rotation speed NE based on the PMB calculation time is determined based on the output PS of the intake pipe pressure sensor 17. The intake pipe pressure PM is obtained by correcting it in addition to the calculated reference intake pipe pressure PMB. The value of the intake pipe pressure PM obtained in this way has less error than the case where the reference intake pipe pressure PMB is corrected by directly using the values of the throttle opening TA and the rotation speed NE, that is, the actual internal combustion engine 10 The value is closer to the intake pipe pressure of. Further, according to steps 360 to 390, the output TA of the throttle opening sensor 16 is A / D converted at the timing when the value of the intake pipe pressure sensor 17 is A / D converted and taken in, that is, immediately before the PSAD calculation timing. Since PMTAB = PMTAi when importing as TAAD, ΔPMTA becomes zero (see Fig. 5 (D)). Therefore, as shown in Fig. 5 (E), the value of the intake pipe pressure PM is the reference intake pipe pressure PMB calculated from PSAD at each timing when the value of the intake pipe pressure sensor 17 is A / D converted and taken in as PSAD. After that, the above-mentioned correction by ΔPMTA is performed based on the reference intake pipe pressure PMB (see Fig. 5 (D)). Therefore, even when this embodiment is continuously and repeatedly used, the intake pipe pressure PM obtained thereby is a value that does not include the accumulation of large errors. In this embodiment, a 4-cylinder independent intake internal combustion engine in which an intake pipe pressure sensor 17 is provided only in a 1-cylinder intake pipe has been described, but naturally, a 6-cylinder internal combustion engine has two intake pipe pressure sensors. Needless to say, it can be applied to an internal combustion engine having four intake pipe pressure sensors for an eight-cylinder internal combustion engine, or in short, having an intake pipe pressure sensor less than the number of cylinders. Further, the intake pipe pressure is proportional to the intake air amount of the internal combustion engine, and it is naturally possible to detect the intake air amount. The PM calculated in this way is then used for various existing controls. For example, it is widely used for calculating the fuel injection amount for keeping the air-fuel ratio of the internal combustion engine 10 at a desired value, calculating the ignition timing for controlling the output torque and emission of the internal combustion engine 10. FIGS. 6A and 6B show an application example of determining the ignition timing of the internal combustion engine 10 by using the intake pipe pressure PM detected by the intake pipe pressure detection device of this embodiment. FIG. 6 (A) is a flowchart for determining the ignition timing, and FIG. 6 (B) is a map explanatory diagram used in the flowchart. The ignition advance calculation routine shown in FIG. 6 (A) is repeatedly executed as a part of the main routine for executing the control of the internal combustion engine 10 or as an independent routine, and the ignition advance of each cylinder, that is, the ignition timing. Calculate how much the best internal combustion engine operation can be ensured. First, in step 400, it is determined whether or not it is time to calculate the ignition advance angle. Whether or not any of the cylinders of the internal combustion engine 10 is approaching the time when ignition is required is determined from the crank angle and the like. Then, the processes of steps 410 to 430 are executed only when it is determined that it is the ignition advance calculation time, and this routine is terminated otherwise. In step 410, the current rotation speed NE of the internal combustion engine 10 and the intake pipe pressure PM are detected. It detects the operating status of the internal combustion engine 10 required to calculate the ignition advance. Here, the rotation speed NE can always be detected by the rotation angle signal from the distributor 15, and the calculation result of the above-described embodiment is used as the intake pipe pressure PM. Therefore, the routine shown in FIG. 4 of the embodiment is executed immediately before the execution of this routine, and the intake pipe pressure PM of the internal combustion engine 10 is required. Next, in step 420, the map for calculating the ignition advance shown in FIG. 6 (B) is searched from the above two values of NE and PM, and the ignition advance is calculated. After that, in step 430, the map search result is stored in the RAM 33, and ignition is performed according to the information in the RAM 33 by an ignition execution routine (not shown). As described above, the intake pipe pressure PM calculated in the above-described embodiment is not different from the intake pipe pressure as a control parameter of the internal combustion engine 10 from the conventional method, and can be widely used as a parameter for all existing controls. is there. Further, since the intake pipe pressure PM is equivalent to the intake air amount Q and Q is in a proportional relationship with M, the intake air amount Q can be easily calculated.

[Effect of the invention] In the first invention, since the correction reference value setting means and the correction means are provided, the change in the opening degree of the throttle valve, that is, the value corresponding to the opening degree of the throttle valve detected by the throttle opening degree detecting means. The intake pipe pressure detected by the pressure detecting means can be corrected based on the deviation from the correction reference value, and the error is smaller than the case where the correction is simply based on the opening degree of the throttle valve. A value corresponding to the intake pipe pressure can be obtained. Further, the value corresponding to the intake pipe pressure of the internal combustion engine thus obtained by the first invention is the intake air detected by the pressure detecting means at each timing when the intake pipe pressure is detected by the pressure detecting means. Since it is corrected to the value of the pipe pressure, there is no accumulation of errors even when the correction is repeated. Therefore, the intake pipe pressure of the independent intake type internal combustion engine can always be accurately detected with a simple structure, even though it is a low-cost device. In the second invention, the same effect as that of the first invention described above is obtained, and the accuracy is further improved because the rotation speed is also taken into consideration. Moreover, since no device such as an air flow meter that acts as a resistance to the intake air is used for the detection, the characteristics of the independent intake type internal combustion engine can be fully exhibited, and pressure interference between the cylinders can be caused. It is an extremely excellent intake pipe pressure detector.

[Simple explanation of drawings]

FIG. 1 (A) is an example diagram of the basic configuration of the first invention, FIG. 1 (B) is an example diagram of the basic configuration of the second invention, and FIG. 2 is a schematic configuration diagram of an embodiment. Fig. 3 (A), (B) and Fig. 4 are the flow charts of the control, Fig. 5 is the timing chart, and Fig. 6 (A) is the flowchart of the application example of the intake pipe pressure obtained in the examples. Figure 6 (B) is a map explanatory diagram of the ignition advance used for the control. 10 ...... Internal combustion engine, 11 ...... Intake pipe, 12 ...... Throttle valve, 15 ...... Distributor, 16 ...... Throttle opening sensor, 17 ...... Intake pipe pressure sensor, 30 ...... Electronic control device