JP4124070B2 - Atmospheric pressure detection device for internal combustion engine - Google Patents

Description

  The present invention relates to an atmospheric pressure detection device for an internal combustion engine that detects an atmospheric pressure of an ambient environment based on a detection value of an intake pressure in an intake passage of each cylinder of an internal combustion engine composed of a single cylinder or multiple cylinders of independent intake. Knowing the change in atmospheric pressure can be reflected in the fuel injection amount supplied to each cylinder of the internal combustion engine.

  Japanese Patent Application Laid-Open No. 10-280995 has been known in which an atmospheric pressure in an ambient environment of an internal combustion engine is detected and, for example, a fuel injection amount is corrected in accordance with the atmospheric pressure to maintain a good operating state of the internal combustion engine. What was disclosed in the publication is known. Like this, in a system in which an atmospheric pressure sensor is provided and the atmospheric pressure is detected from the detection result, a cost increase corresponding to that is unavoidable, leading to an increase in the price of the entire system.

As what copes with this, what was disclosed by Unexamined-Japanese-Patent No. 2002-30981 is known. This technique shows a technique for detecting the atmospheric pressure without incurring a cost increase by using a detection value of an intake pressure sensor disposed in an intake passage of an internal combustion engine.
JP-A-10-280995 (2nd page) JP 2002-30981 A (pages 2 to 3)

  By the way, in the above-mentioned Japanese Patent Application Laid-Open No. 2002-30981, the atmospheric pressure sensor is made unnecessary by approximately obtaining the atmospheric pressure based on the intake pressure when the atmospheric pressure detection execution condition based on the operating state of the internal combustion engine is satisfied. Yes. Even if there is no atmospheric pressure sensor, there is a period in which the intake pressure is considered to be almost atmospheric pressure immediately before the intake stroke in the middle / high load operation region after the start of the internal combustion engine. If attention is paid to this period, it is possible to approximately obtain the atmospheric pressure based on the intake pressure.

  However, at the time of idling after the start of the internal combustion engine or in the low load operation region, there is no period in which the intake pressure is regarded as almost atmospheric pressure even immediately before the intake stroke. When there is a mistake in taking in the atmospheric pressure, or when going downhill only by controlling the engine brake or low-load operating area on a long downhill, the atmospheric pressure cannot be detected, and fuel injection supplied to the internal combustion engine There is a possibility that the operation amount of the internal combustion engine becomes unsatisfactory due to an inappropriate amount.

  Therefore, the present invention was made to eliminate the predictability of such problems, and does not require an atmospheric pressure sensor, and can detect atmospheric pressure based on the intake pressure in the entire operating range regardless of the load state of the internal combustion engine. An object is to provide an atmospheric pressure detection device for an internal combustion engine.

  According to the atmospheric pressure detection device for an internal combustion engine of claim 1, the period during which the intake valve is closed is specified by the crank angle position by the crank angle detection means in the same combustion cycle of the internal combustion engine by the atmospheric pressure calculation means, Atmospheric pressure is calculated based on the throttle opening by the throttle opening detecting means and the intake pressure by the intake pressure detecting means at one point in the period, and the intake pressure change per unit time after a predetermined period from that point. Therefore, the atmospheric pressure is obtained based on the throttle opening and the intake pressure in the entire operation region without requiring an atmospheric pressure sensor and regardless of the load state of the internal combustion engine. For this reason, for example, even if there is a mistake in taking in atmospheric pressure before the start of start, or when descending only by control of an engine brake or a low load operation region on a long downhill, the atmospheric pressure is sequentially obtained. As a result, the fuel injection amount to be supplied to the internal combustion engine is suitably corrected, and the operation state is maintained favorably.

  In the throttle opening degree detecting means in the atmospheric pressure detecting device of the internal combustion engine according to the second aspect, the throttle opening degree including the ISC control amount of the ISC valve for adjusting the intake air amount by bypassing the throttle valve is detected. Thus, in a system having an ISC valve in addition to a throttle valve, an ISC control amount of the ISC valve is added to the throttle opening of the throttle valve in order to set the intake air amount introduced downstream of the throttle valve. In this configuration, the actual throttle opening is appropriately detected.

  In the atmospheric pressure calculation means in the atmospheric pressure detection apparatus for an internal combustion engine according to claim 3, the atmospheric pressure is calculated when the intake pressure is at least one of the latest atmospheric pressures at about 52.8%. . That is, when calculating the atmospheric pressure, an execution condition indicating whether the intake pressure is approximately 52.8 [%] of the latest atmospheric pressure is added. The effect is obtained that the atmospheric pressure is detected based on the intake pressure in the entire operation region of the engine.

  In the atmospheric pressure calculation means in the atmospheric pressure detection device for an internal combustion engine according to claim 4, the throttle opening and the amount of change in intake pressure per unit time with the intake pressure approximately 52.8% of the latest atmospheric pressure as a boundary. Is used to switch the map for calculating atmospheric pressure using and as parameters. As described above, the map for calculating the atmospheric pressure using the throttle opening and the amount of change in the intake pressure per unit time as parameters before and after the intake pressure is approximately 52.8% of the latest atmospheric pressure is switched. The effect is obtained that the atmospheric pressure is calculated with high accuracy.

  According to the atmospheric pressure detecting device for an internal combustion engine of claim 5, the intake air temperature detected by the intake air temperature detecting means is set to a value obtained by the atmospheric pressure calculating means using a map using the throttle opening and the intake pressure change amount per unit time as parameters. By applying the correction according to the above, an effect that the atmospheric pressure is calculated with higher accuracy can be obtained.

  In the atmospheric pressure detecting device for an internal combustion engine according to claim 6, since the internal combustion engine is composed of a single cylinder or multiple cylinders of independent intake, and an intake pressure detecting means is provided for each cylinder, the intake valve in each cylinder is closed. There is an effect that the intake pressure is stably detected by the intake pressure detection means corresponding to the section.

  Hereinafter, the best mode for carrying out the present invention will be described based on examples.

  FIG. 1 is a schematic configuration diagram showing an internal combustion engine and its peripheral devices in a motorcycle to which an atmospheric pressure detection device for an internal combustion engine according to an embodiment of the present invention is applied.

  In FIG. 1, an internal combustion engine 1 is configured as a four-cycle single cylinder spark ignition type, and its intake air passes through an air cleaner 2, an intake passage 3, and a throttle valve 4 from the upstream side, and enters an injector (fuel injection) in the intake passage 3. The fuel is injected from the fuel injected from the valve (5) and supplied to the cylinder as an air-fuel mixture having a predetermined air-fuel ratio from the intake port 6 as the intake valve 7 is opened and closed. An ignition plug 8 is disposed in the cylinder head of the internal combustion engine 1, and a high voltage is applied from the ignition coil / igniter 9 to the ignition plug 8 at each ignition timing to ignite the air-fuel mixture in the cylinder. The exhaust gas burned in the cylinder of the internal combustion engine 1 passes through the three-way catalyst 13 disposed on the downstream side of the exhaust passage 12 from the exhaust port 11 as the exhaust valve 10 is opened and closed, and is discharged into the atmosphere. Is done.

  An intake air temperature sensor 21 is disposed in the air cleaner 2, and the intake air temperature THA [° C.] flowing into the air cleaner 2 is detected by the intake air temperature sensor 21. An intake pressure sensor 22 is disposed in the intake passage 3, and the intake pressure sensor 22 detects an intake pressure PM [kPa: kilopascals] on the downstream side of the throttle valve 4. The throttle valve 4 is provided with a throttle opening sensor 23, which detects the throttle opening TA [°] of the throttle valve 4. A water temperature sensor 24 is disposed in the cylinder block of the internal combustion engine 1, and the coolant temperature THW [° C.] in the internal combustion engine 1 is detected by the water temperature sensor 24.

  A crank angle sensor 25 is disposed on a crankshaft (not shown) of the internal combustion engine 1, and a crank angle [° CA (Crank Angle)] accompanying rotation of the crankshaft is detected by the crank angle sensor 25. The engine speed NE [rpm] of the internal combustion engine 1 is calculated according to the crank angle signal detected by the crank angle sensor 25. Further, the cylinder discrimination and the crank angle reference position are detected based on the crank angle signal from the crank angle sensor 25 and the fluctuation of the intake pressure by the intake pressure sensor 22 accompanying the combustion cycle. In addition, a power supply voltage sensor 29 is provided in the in-vehicle battery (not shown), and the power supply voltage sensor 29 detects the power supply voltage VB [V: volts].

  On the other hand, the fuel pumped up from the fuel tank 31 by the fuel pump 32 is pumped in the order of the fuel pipe 33, the fuel filter 34, the fuel pipe 35, and the delivery pipe 36 and is supplied to the injector 5. Excess fuel in the delivery pipe 36 is returned into the fuel tank 31 through a path of a pressure regulator 37 and a return pipe 38. The pressure regulator 37 adjusts the fuel pressure in the delivery pipe 36 so that the differential pressure between the fuel pressure (fuel pressure) in the delivery pipe 36 and the intake pressure becomes constant.

  An ECU (Electronic Control Unit) 40 that controls the operating state of the internal combustion engine 1 includes a CPU 41 as a central processing unit that executes various known arithmetic processes, a ROM 42 that stores a control program, a control map, and various data. Are composed of a logical operation circuit centered on a RAM 43, a B / U (backup) RAM 44, etc., and various input actuators such as an injector 45, a fuel pump 32, etc. A bus 47 is connected to an output port 46 for outputting each control signal to the ignition coil / igniter 9.

  Next, the behavior of the intake pressure [kPa] in the intake stroke → compression stroke → combustion (expansion) stroke → exhaust stroke, which is one combustion cycle (720 [° CA]) of the internal combustion engine 1 of the present embodiment, is shown in FIG. This will be described with reference to a time chart.

  As shown in FIG. 2, the intake pressure in the high / medium load range where the throttle opening is “large / medium (open side)” increases from atmospheric pressure to the positive pressure side for a moment at the beginning of the intake stroke, and then increases to the negative pressure side. After decreasing and reaching the minimum value (bottom pressure), it starts to increase by the beginning of the compression stroke and returns to the atmospheric pressure level by the end of the combustion stroke. For this reason, although depending on the operating state of the internal combustion engine 1, it can be said that the intake pressure in the exhaust stroke is at the atmospheric pressure level.

  Here, when the engine speed NE is constant, the minimum value of the intake pressure increases as the throttle opening increases from “small (closed side)” to “large”, and increases from the minimum value to the atmospheric pressure level. Speed to do. For this reason, as the throttle opening becomes “large”, the intake pressure intake period can be extended to the combustion stroke and further to the middle of the compression stroke in addition to the exhaust stroke. Thus, the atmospheric pressure can be estimated by sequentially taking in the intake pressure at the timing when the intake pressure reaches the atmospheric pressure level.

  By the way, as shown in FIG. 2, in the low load region where the throttle opening is “small”, the intake pressure does not rise to the atmospheric pressure, that is, the intake pressure does not reach the atmospheric pressure level. Even if it was taken in, atmospheric pressure estimation was impossible. A process for coping with this and enabling the atmospheric pressure to be obtained from the intake pressure even in a low load range where the throttle opening is “small” will be described below.

  Based on the flowchart of FIG. 3 which shows the processing procedure of the atmospheric pressure calculation in CPU41 in ECU40 used by the present Example, it demonstrates with reference to above-mentioned FIG.2 and FIG.4. Here, FIG. 4 corresponds to the processing of FIG. 3, and is a time chart showing transition states of various control amounts and the like during a downhill in a fully closed low load region where the throttle opening degree TA [°] is “minimum”. is there. The atmospheric pressure calculation routine is repeatedly executed by the CPU 41 about every 2 [ms: milliseconds] or every time a crank angle signal is input.

  In FIG. 3, in step S101, it is first determined whether or not it is in the intake pressure detection region. Here, as shown in FIG. 2 as the detection permission period, it is determined whether the intake valve 7 is in the closed period determined by the crank angle signal. When the determination condition of step S101 is not satisfied, that is, when the intake valve 7 is not closed, this routine is terminated without doing anything.

  On the other hand, when the determination condition of step S101 is satisfied, that is, when the intake valve 7 is closed, the routine proceeds to step S102, where the throttle opening degree TA [°] detected by the throttle opening degree sensor 23 is, for example, The full closure shown in 4 is read. Next, the process proceeds to step S103 where the current intake pressure PM [kPa] and the previous intake pressure PMO [kPa] are read as the intake pressure for a predetermined period detected by the intake pressure sensor 22. Here, the predetermined period is set in advance, for example, as a period of time from the predetermined crank angle signal to the predetermined crank angle signal, or a predetermined time from the predetermined crank angle signal.

  Next, in step S104, the intake pressure change amount ΔPM [kPa] for a predetermined period is calculated by subtracting the previous intake pressure PMO from the current intake pressure PM. Next, the process proceeds to step S105, and the intake pressure change amount ΔPMT per unit time with respect to the intake pressure change amount ΔPM [kPa] calculated in step S104 is calculated. Note that, as shown in FIG. 4, the air pressure normally increases as the road goes down from a highland to a flatland, so that the intake pressure change amount ΔPMT increases. Next, the process proceeds to step S106, and the intake air temperature THA [° C.] detected by the intake air temperature sensor 21 is read. Next, the process proceeds to step S107, on the basis of a map (not shown) using the throttle opening TA [°] read in step S102 and the intake pressure change amount ΔPMT per unit time calculated in step S105 as parameters. As shown in FIG. 4, an atmospheric pressure correction value PAS is calculated. This map is switched with respect to the latest atmospheric pressure calculated by the current intake pressure at the boundary of the intake pressure of about 52.8 [%].

The basis of about 52.8 [%] of this map switching will be briefly described below. Unit that a suction air at about 52.8 [%] before and after the intake air pressure P _M is the atmospheric pressure (absolute pressure) P ₀ is due to exceed sonic velocity, the intake air pressure P _M is returned to the atmospheric pressure P ₀ Since the intake pressure change amount (slope) ΔPMT per hour greatly changes, map switching is effective to increase the accuracy in calculating the atmospheric pressure. About 52.8 [%] is obtained by the following equation (1). Note that κ is the specific heat ratio of air and is about 1.4.

・・・（１）

... (1)

  Next, the process proceeds to step S108, and the intake air temperature correction value KTHA is calculated based on a table (not shown) using the intake air temperature THA [° C.] read in step S106 as a parameter. Next, the process proceeds to step S109, and a value obtained by multiplying the atmospheric pressure correction value PAS and the intake air temperature correction value KTHA is added to the previous intake pressure PMO [kPa] to obtain the current atmospheric pressure PA calculated value [kPa]. This routine is terminated. As shown in FIG. 4, the atmospheric pressure PA calculation value increases as the slope goes down from the high ground to the flat ground.

  As described above, the atmospheric pressure detection device for the internal combustion engine of the present embodiment detects the intake pressure PM that is the pressure of the intake air introduced to the downstream side of the throttle valve 4 disposed in the intake passage 3 of the internal combustion engine 1. An intake pressure sensor 22 serving as an intake pressure detection means, a crank angle sensor 25 serving as a crank angle detection means for detecting a predetermined crank angle position of the internal combustion engine 1, and an intake air amount introduced downstream of the throttle valve 4 A throttle opening degree sensor 23 as a throttle opening degree detecting means for detecting the throttle opening degree TA of the throttle valve 4 and a period during which the intake valve 7 is closed as a detection permission period in the same combustion cycle of the internal combustion engine 1 The throttle angle TA and the intake pressure PMO at one point P (O) shown in FIG. 2 specified during the crank angle position and the intake pressure at the one point P (O) shown in FIG. Atmospheric pressure calculation means achieved by the ECU 40 that calculates the atmospheric pressure PA based on the intake pressure change amount ΔPMT per unit time after a predetermined period determined by MO and the intake pressure PM at the point P (N) shown in FIG. It comprises. In addition, the internal combustion engine 1 to which the atmospheric pressure detection device for an internal combustion engine of the present embodiment is applied is a single cylinder.

  That is, in the same combustion cycle of the single-cylinder internal combustion engine 1, the throttle opening degree TA and the intake pressure PMO at one point P (O) within the closed period of the intake valve 7 as the detection permission period, and the one point P ( The atmospheric pressure PA is calculated on the basis of the intake pressure change amount ΔPMT per unit time after a predetermined period determined by the intake pressure PMO at O) and the intake pressure PM at the point P (N).

  For this reason, the atmospheric pressure is obtained based on the throttle opening and the intake pressure in the entire operation region without requiring an atmospheric pressure sensor and regardless of the load state of the internal combustion engine. As a result, even if there is a mistake in taking in the atmospheric pressure before the start of the start, or when downhill only by control of the engine brake or low load operation area on a long downhill, the atmospheric pressure can be obtained sequentially. The fuel injection amount supplied to the internal combustion engine is suitably corrected, and the operation state can be maintained satisfactorily.

  Then, the atmospheric pressure calculation means achieved by the ECU 40 of the atmospheric pressure detecting device for the internal combustion engine of the present embodiment is that the throttle opening TA is set at the boundary of the intake pressure of about 52.8% of the latest atmospheric pressure. And an atmospheric pressure calculation map (not shown) using the intake air pressure change amount per unit time as a parameter. Thus, the atmospheric pressure is switched by switching the map using the throttle opening TA and the intake pressure change amount ΔPMT per unit time as parameters before and after the intake pressure is approximately 52.8% of the latest atmospheric pressure. The correction value PAS can be calculated with high accuracy.

  Further, the atmospheric pressure detection device for the internal combustion engine of the present embodiment includes an intake air temperature sensor 21 as an intake air temperature detection means for detecting an intake air temperature THA that is the temperature of the intake air introduced into the internal combustion engine 1. The atmospheric pressure calculation means achieved in this way is a correction using an intake air temperature correction value KTHA to an atmospheric pressure correction value PAS obtained from a map (not shown) using the throttle opening degree TA and the intake pressure change amount PMT per unit time as parameters. Is added. Thus, the atmospheric pressure correction value PAS can be calculated with higher accuracy by correcting the atmospheric pressure correction value PAS with the intake air temperature correction value KTHA.

  By the way, in the said Example, although the structure by which the intake air amount introduced into the downstream is set only by throttle opening TA of the throttle valve 4 was assumed, when implementing this invention, it is limited to this. In this configuration, an ISC valve that bypasses the throttle valve 4 to adjust the amount of intake air is set. The throttle valve includes an ISC control amount by the ISC valve in addition to the throttle opening TA of the throttle valve 4. The amount of intake air introduced to the downstream side of 4 may be set.

  Such an atmospheric pressure detection device for an internal combustion engine detects a throttle opening that includes an ISC control amount of an ISC valve that adjusts an intake air amount that bypasses the throttle valve by a throttle opening detection means. By adding the ISC control amount of the ISC valve to the throttle opening of the throttle valve is detected as the actual throttle opening in this configuration, the same operation and effect as in the above embodiment can be obtained.

  In the above embodiment, the map is switched with the intake pressure at about 52.8 [%] of the latest atmospheric pressure as a boundary. However, the present invention is not limited to this. Even if the atmospheric pressure is calculated when the intake pressure is approximately 52.8 [%] of the latest atmospheric pressure and at least one of them, the operating state of the internal combustion engine 1 satisfies this execution condition. Since the atmospheric pressure is calculated at this time, there is a possibility that the opportunity will be less than in the above embodiment. However, as in the above embodiment, the atmospheric pressure is detected based on the intake pressure in the entire operation region of the internal combustion engine 1. Will be able to.

  In the above embodiment, the application to an internal combustion engine consisting of a single cylinder has been described. However, the present invention is not limited to this, and may be an internal combustion engine consisting of multiple cylinders with independent intake. For example, the intake pressure sensor for detecting the intake pressure is disposed on the downstream side of the throttle valve in the intake passage of each cylinder. I can expect.

FIG. 1 is a schematic configuration diagram showing an internal combustion engine and its peripheral devices in a motorcycle to which an atmospheric pressure detection device for an internal combustion engine according to an embodiment of the present invention is applied. FIG. 2 is a time chart showing the behavior of the intake pressure in the combustion cycle of the internal combustion engine of FIG. FIG. 3 is a flowchart showing a processing procedure of the atmospheric pressure calculation in the CPU in the ECU used in the atmospheric pressure detecting device for the internal combustion engine according to the embodiment of the present invention. FIG. 4 is a time chart showing transition states such as various control amounts corresponding to the processing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Intake passage 4 Throttle valve 7 Intake valve 22 Intake pressure sensor 23 Throttle opening sensor 25 Crank angle sensor 40 ECU (electronic control unit)

Claims (6)

An intake pressure detecting means for detecting an intake pressure that is a pressure of intake air introduced downstream of a throttle valve disposed in an intake passage of the internal combustion engine;
Crank angle detecting means for detecting a predetermined crank angle position of the internal combustion engine;
Throttle opening detection means for detecting the throttle opening of the throttle valve for setting the amount of intake air introduced downstream of the throttle valve;
In the same combustion cycle of the internal combustion engine, the period during which the intake valve is closed is specified by the crank angle position, and the throttle opening and intake pressure at one point within that period, the unit time after the predetermined period from that point An atmospheric pressure detecting device for an internal combustion engine, comprising: an atmospheric pressure calculating means for calculating an atmospheric pressure based on the amount of change in the intake pressure per hit.   The throttle opening detecting means detects the throttle opening including an ISC control amount of an ISC (Idle Speed Control) valve that adjusts an intake air amount that bypasses the throttle valve. The atmospheric pressure detection apparatus for an internal combustion engine according to claim 1, wherein the apparatus is an atmospheric pressure detection apparatus.   3. The atmospheric pressure calculating means calculates the atmospheric pressure when the intake pressure is at least one of the latest atmospheric pressure at about 52.8 [%] as a boundary. An atmospheric pressure detection device for an internal combustion engine according to claim 1.   The atmospheric pressure calculation means calculates atmospheric pressure using the throttle opening and the amount of change in intake air pressure per unit time as parameters, with the intake air pressure approximately 52.8 [%] of the latest atmospheric pressure. The atmospheric pressure detection device for an internal combustion engine according to any one of claims 1 to 3, wherein the map is switched. An intake air temperature detecting means for detecting an intake air temperature which is a temperature of intake air introduced into the internal combustion engine;
2. The atmospheric pressure calculation means adds a correction according to the intake air temperature to a value obtained by a map using the throttle opening and the intake pressure change per unit time as parameters. The atmospheric pressure detection device for an internal combustion engine according to claim 4.   The internal combustion engine according to any one of claims 1 to 5, wherein the internal combustion engine includes a single cylinder or multiple cylinders of independent intake, and the intake pressure detection means is provided for each cylinder. Atmospheric pressure detector.

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