JP2013029067A - Device for estimating condition of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for estimating a condition of an internal combustion engine, capable of obtaining the pressure of an intake or exhaust system more easily, which is the engine condition necessary for the internal combustion engine control or the like.SOLUTION: The device for estimating the condition of the internal combustion engine includes a cylinder pressure sensor 45 for measuring a pressure in a cylinder 12. Based on a detection value of the cylinder pressure sensor 45 during a valve opening period of an intake valve 22 for opening and closing an intake port 21a of the cylinder 12 and an exhaust valve 24 for opening and closing an exhaust port 23a of the cylinder 12, at least one of the intake pressure or the exhaust pressure of the internal combustion engine 11 is estimated as the engine condition.

Description

  The present invention relates to an internal combustion engine state estimation device that estimates an intake system or exhaust system pressure as an engine state required for control of an internal combustion engine.

  Control of an internal combustion engine often requires intake system pressure (intake pressure) and exhaust system pressure (exhaust pressure). Usually, these pressures are measured by respective pressure sensors respectively provided in the exhaust system and the intake system. These pressure sensors are required to have high durability so that their malfunctions do not reduce the reliability in controlling the internal combustion engine. On the other hand, sensors with excellent durability are installed. An increase in the cost of the engine system due to this is inevitable. Therefore, in recent years, a technique for reducing pressure sensors necessary for obtaining intake pressure and exhaust pressure has been proposed, and an example thereof is described in Patent Document 1.

  In the pressure estimation device described in Patent Document 1, the exhaust pressure is calculated by applying the exhaust temperature estimated based on a plurality of engine states and the exhaust flow rate calculated based on the plurality of engine states to Bernoulli's equation. . At this time, the exhaust temperature is obtained based on the fuel injection amount, the intake air temperature, and the fuel injection timing, and the exhaust flow rate is obtained as the exhaust flow rate at the time of cylinder discharge based on the intake air flow rate and the engine rotation speed. That is, in this pressure estimation device, the exhaust pressure is estimated based on a plurality of engine operating parameters such as the fuel injection amount, the intake air temperature, the fuel injection timing, the intake air flow rate, and the engine speed.

JP-A-10-26049

  If the exhaust pressure is estimated using a plurality of operation parameters as in the pressure estimation device described in Patent Document 1, the number of pressure sensors that measure the exhaust pressure can be reduced. However, when exhaust pressure is estimated based on a large number of operating parameters, the calculation method increases because the calculation method is complicated and it takes time to calculate, so the influence of the calculation load on the processing capacity of the control device can be ignored. The adoption is not always easy.

  The present invention has been made in view of such circumstances, and an object thereof is an internal combustion engine that can more easily obtain the pressure of an intake system and an exhaust system, which are engine states necessary for control of the internal combustion engine and the like. It is in providing the state estimation apparatus of this.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
In order to solve the above-described problem, the invention described in claim 1 includes an in-cylinder pressure sensor that measures the pressure in the cylinder, and opens and closes an intake valve that opens and closes the intake port of the cylinder and an exhaust port of the cylinder. The gist is to estimate at least one of an intake pressure and an exhaust pressure of an internal combustion engine as an engine state based on a detection value of the in-cylinder pressure sensor during a valve opening period of the exhaust valve.

  According to such a configuration, the intake pressure and the exhaust pressure are estimated based on the pressure in the cylinder during the opening period of the intake valve and the exhaust valve, so that the intake pressure and the exhaust pressure are measured. It is not necessary to provide a pressure sensor in the intake passage or the exhaust passage. By doing so, the internal combustion engine state estimating apparatus can easily estimate the intake pressure and the exhaust pressure.

In addition, the intake air amount can be obtained from the intake pressure estimated by using a map that can obtain the intake air amount based on the intake pressure.
According to a second aspect of the present invention, in the internal combustion engine state estimating apparatus according to the first aspect, the intake pressure and the exhaust pressure are controlled by utilizing a repetitive characteristic of a pressure waveform based on a detection value of the in-cylinder pressure sensor. The gist is to estimate the pressure in at least one arbitrary period as the engine state.

  According to such a configuration, the intake pressure and the exhaust pressure during one cycle can be estimated from the detection values of the in-cylinder pressure sensor. For example, if the intake valve or exhaust valve is open, the value detected by the in-cylinder pressure sensor can be used as an estimated value of intake pressure or exhaust pressure, and the intake valve or exhaust valve is closed. If the detected value of the in-cylinder pressure sensor is corresponding to the intake valve or exhaust valve of the other cylinder during the open period, the intake pressure and exhaust pressure of the other cylinder are At least one of the atmospheric pressures can be estimated. As a result, the number of pressure sensors required for measuring the intake pressure and the exhaust pressure can be reduced, and the number of in-cylinder pressure sensors required for estimating the intake pressure and the exhaust pressure can also be reduced. It becomes like this.

  According to a third aspect of the present invention, in the internal combustion engine state estimating apparatus according to the first or second aspect, the in-cylinder pressure sensor is located on a side surface of the cylinder forming the cylinder, and is located above the piston. The gist is that it is arranged at a position closer to the combustion chamber than the dead center.

  According to such a configuration, since the in-cylinder pressure sensor can always measure the pressure in the combustion chamber partitioned in the cylinder, it is possible to control the internal combustion engine such as obtaining continuous pressure data. convenient.

  According to a fourth aspect of the present invention, in the internal combustion engine state estimating apparatus according to the first or second aspect, the in-cylinder pressure sensor is located on a side surface of the cylinder forming the cylinder, and the piston is at the upper side. The gist is that it is arranged at a position covered by the piston when the dead center is reached.

  According to such a configuration, in the compression / expansion stroke of the internal combustion engine, when the combustion chamber becomes high temperature and high pressure due to combustion, that is, when the capacity of the combustion chamber is minimized, the in-cylinder pressure sensor is covered by the piston and burned. Temporarily isolated from the room. As a result, the in-cylinder pressure sensor can avoid high temperature and high pressure in the combustion chamber, particularly high temperature and high pressure peaks. That is, the chance that the in-cylinder pressure sensor is exposed to high temperature or high pressure can be reduced. As a result, the pressure resistance of the pressure sensor can be lowered. Normally, the measurement range and pressure resistance of the in-cylinder pressure sensor are proportional to each other, so a sensor with a high pressure resistance has a wide measurement range, but the measurement accuracy is low, but the measurement range is narrowed by reducing the pressure resistance. Thus, the measurement accuracy in the measurement range necessary for estimating the intake pressure and the exhaust pressure can be increased.

  According to this configuration, there is a range where the in-cylinder pressure sensor cannot measure the pressure in the range where the intake pressure or the exhaust pressure is estimated. These pressures may be complemented by various complementing processes such as maintaining the pressure at the immediately preceding measurement pressure. This reduces costs by reducing the pressure resistance of the in-cylinder pressure sensor employed in the state estimation device for the internal combustion engine, maintains reliability by suppressing failures due to high pressure, and the like. The degree of freedom in design can be improved.

  According to a fifth aspect of the present invention, in the internal combustion engine state estimating device according to any one of the first to fourth aspects, the internal combustion engine is a V-type multi-cylinder engine, and the in-cylinder pressure sensor is a bank. Separately, it is provided for one representative cylinder.

  According to such a configuration, since the in-cylinder pressure sensor is provided only in one representative cylinder among the plurality of cylinders constituting the bank, the pressure for measuring the intake pressure and the exhaust pressure in the V-type multi-cylinder engine. Not only the sensor but also the in-cylinder pressure sensor provided in the cylinder can be reduced.

  The invention according to claim 6 is the internal combustion engine state estimation device according to any one of claims 1 to 4, wherein the internal combustion engine is an in-line multi-cylinder engine, and the in-cylinder pressure sensor is representative. The gist is that it is provided for one cylinder.

  According to such a configuration, since the in-cylinder pressure sensor is provided only in one representative cylinder among the plurality of cylinders, in the in-line multi-cylinder engine, not only the pressure sensor for measuring the intake pressure and the exhaust pressure, In-cylinder pressure sensors provided in the cylinder can also be reduced.

The schematic diagram which shows the schematic structure about 1st Embodiment which actualized the internal combustion engine provided with the state estimation apparatus of the internal combustion engine which concerns on this invention. The graph which shows the relationship between the intake pressure and cylinder pressure in the internal combustion engine of the embodiment. The graph which shows the relationship between the exhaust pressure and the cylinder pressure in the internal combustion engine of the embodiment. The graph shown about the intake pressure corresponding to 1 cycle in the internal combustion engine of the embodiment, and the intake pressure estimated from in-cylinder pressure. The graph which shows about the exhaust pressure corresponding to 1 cycle in the internal combustion engine of the embodiment, and the exhaust pressure estimated from the cylinder pressure. 6 is a flowchart showing a procedure for estimating and outputting intake pressure and exhaust pressure in the internal combustion engine of the embodiment. The schematic diagram which shows the schematic structure about 2nd Embodiment which actualized the internal combustion engine provided with the state estimation apparatus of the internal combustion engine which concerns on this invention. The graph which shows the relationship between the intake pressure and cylinder pressure in the internal combustion engine of the embodiment. The graph which shows the relationship between the exhaust pressure and the cylinder pressure in the internal combustion engine of the embodiment. The schematic diagram which shows the schematic structure about other embodiment which actualized the internal combustion engine provided with the state estimation apparatus of the internal combustion engine which concerns on this invention.

(First embodiment)
Hereinafter, a first embodiment of an internal combustion engine provided with an internal combustion engine state estimation device according to the present invention will be described with reference to FIG. Since the internal combustion engine of the present embodiment is a V-type 6 cylinder having six cylinders, the banks arranged on the left and right have three cylinders, respectively, one intake passage 21 and one exhaust. A passage 23 is connected. That is, the intake passage 21 and the exhaust passage 23 are shared by the three cylinders of the corresponding bank.

  As shown in FIG. 1, a piston 13 is provided in each cylinder 12 of the internal combustion engine 11 so as to be capable of reciprocating. Each cylinder 12 has a combustion chamber 14 defined by the top surface of the piston 13 and the inner surface of the cylinder 12. That is, the piston 13 moves its top surface between the position of the bottom dead center BDC and the position of the top dead center TDC by the reciprocating motion in the cylinder 12, and the capacity of the combustion chamber 14 partitioned by the top surface. Increase or decrease. For example, when the top surface of the piston 13 is arranged at the top dead center TDC, the capacity of the combustion chamber 14 is minimized.

  The internal combustion engine 11 is provided with a fuel injection valve 15 for injecting fuel separately for each cylinder 12. In each combustion chamber 14, the air-fuel mixture composed of intake air and injected fuel is ignited by the spark plug 16, whereby the air-fuel mixture is combusted and the piston 13 reciprocates to serve as an output shaft. The crankshaft 31 rotates. The driving force of the crankshaft 31 is transmitted to driving wheels (not shown) via a transmission or the like.

  Further, each cylinder 12 is provided with an in-cylinder pressure sensor 45 capable of measuring a pressure in the combustion chamber 14, that is, a so-called in-cylinder pressure CP, and outputting the in-cylinder pressure CP as a detection value. In other words, the in-cylinder pressure sensor 45 has a detecting portion arranged on the side surface of the cylinder forming the cylinder 12. In the present embodiment, the in-cylinder pressure sensor 45 is provided on the side surface of the cylinder and at a position closer to the combustion chamber 14 than the top dead center TDC, which is a position not covered by the piston 13 regardless of the position of the piston 13. It has been. From this, the in-cylinder pressure sensor 45 can measure the pressure in the combustion chamber 14 even when the piston 13 is at the position of the top dead center TDC. Therefore, from the top dead center TDC where the piston 13 reciprocates. The pressure in the combustion chamber 14 can be measured over the entire range of the bottom dead center BDC.

  In the internal combustion engine 11, the intake port 21 a, which is a communication portion of the intake passage 21 to the combustion chamber 14, is connected and cut off by the opening / closing operation of the intake valve 22. Further, the internal combustion engine 11 is communicated / blocked between the combustion chamber 14 and the exhaust port 23 a, which is a communication portion of the exhaust passage 23, with the opening / closing operation of the exhaust valve 24. That is, the intake passage 21 connected to the combustion chamber 14 is opened and closed in the cylinder 12 by the intake valve 22, and the exhaust passage 23 connected to the combustion chamber 14 is opened and closed in the cylinder 12 by the exhaust valve 24. The intake valve 22 opens and closes with the rotation of the intake camshaft 26 to which the rotation of the crankshaft 31 is transmitted, and the exhaust valve 24 opens and closes with the rotation of the exhaust camshaft 27 to which the rotation of the crankshaft 31 is transmitted. Operate.

  Various controls of the internal combustion engine 11 are performed by an electronic control unit (hereinafter, ECU) 41 mounted on the vehicle. The ECU 41 inputs a CPU that executes arithmetic processing related to the control of the internal combustion engine 11, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores the arithmetic results of the CPU, and an external signal input For example, and an output port for outputting a signal to the outside. In particular, in the present embodiment, the program and data include processing for obtaining the intake pressure and exhaust pressure as the engine state, parameters necessary for the processing, and the like. A necessary parameter or the like includes a map that can obtain the intake air amount based on the intake pressure.

  Various sensors for detecting the state of the internal combustion engine 11 and the vehicle are connected to the input port of the ECU 41. Examples of the various sensors include a crank position sensor 42 for detecting a crank angle CA that is a rotation angle of the crankshaft 31 and an engine rotation speed NE that is a rotation speed of the crankshaft 31. Examples of the various sensors include an intake cam position sensor 43 for detecting the rotation angle of the intake cam shaft 26 and an exhaust cam position sensor 44 for detecting the rotation angle of the exhaust cam shaft 27. Furthermore, as various sensors, the said cylinder pressure sensor 45 which outputs the measured cylinder pressure CP as a detection value is mentioned. Note that the ECU 41 can hold the in-cylinder pressure CP in at least one cycle of the internal combustion engine in association with the crank angle CA. Various sensors include a shift position sensor 46 for detecting a shift position of a shift lever (not shown) operated by a driver, an accelerator position sensor 47 for detecting an accelerator depression amount, and an operation state of a brake pedal. Examples thereof include a brake sensor 48 for detecting, a vehicle speed sensor 49 for detecting a vehicle traveling speed, and the like.

  On the other hand, the fuel injection valve 15, the spark plug 16, and the like are electrically connected to the output port of the ECU 41. The ECU 41 performs various controls such as fuel injection and ignition timing based on the detection results of the various sensors described above. Specifically, cylinder discrimination is performed based on signals output from the crank position sensor 42, the intake cam position sensor 43, and the exhaust cam position sensor 44, and the fuel injection timing and ignition for each cylinder 12 based on the crank angle CA. Set the time.

  Next, with reference to FIG. 2, the relationship between the opening / closing operation of the intake valve 22, the in-cylinder pressure CP, and the intake pressure will be described. One bank is provided with three cylinders 12 having the same configuration. In this embodiment, one of the three cylinders 12 is a cylinder 12 representing the bank. For convenience of explanation, the state estimation device for the internal combustion engine 11 will be described focusing on the cylinder 12 as a representative example.

  As shown in FIG. 2, when the intake stroke is started, the intake valve 22 is in a state where the valve lift amount VLi is larger than “0” from the closed state where the valve lift amount VLi is “0”, that is, opened. Transition to the valve state. Then, after the valve lift amount VLi becomes the maximum, the intake valve 22 becomes smaller, and when it becomes “0”, the intake valve 22 is closed and the intake stroke is completed. For example, in FIG. 2, the intake valve 22 starts the intake stroke from a crank angle smaller than 360 ° (360 ° CA), and the valve lift amount VLi is maximized at 450 ° CA and reaches 540 ° CA. After that, the inhalation process ends. In this intake stroke, the in-cylinder pressure sensor 45 detects a pressure that fluctuates in the vicinity of the atmospheric pressure P0 as the in-cylinder pressure CP in the combustion chamber 14. Further, in the same intake stroke, a test pressure sensor provided on a trial basis in the intake passage 21 detects a pressure that fluctuates in the vicinity of the atmospheric pressure P 0 as the intake pressure IP that is the pressure in the intake passage 21.

  By the way, when the intake pressure IP and the in-cylinder pressure CP thus measured are compared in the range SI corresponding to the intake stroke, the intake pressure IP and the in-cylinder pressure CP are similar in value and fluctuation. I understand that. The in-cylinder pressure CP may include abrupt fluctuations due to noise or the like. However, by performing processing such as regulating such level fluctuations with a filter or leveling, the cylinder pressure can be reduced during the intake stroke. The internal pressure CP can be made more similar to the intake pressure IP. For this reason, the ECU 41 of the present embodiment uses the in-cylinder pressure CP in place of the intake pressure IP of the intake passage 21 in the intake stroke. That is, the in-cylinder pressure CP is used as the estimated value of the intake pressure IP. The ECU 41 may use a value obtained by performing a predetermined process on the in-cylinder pressure CP as the estimated value of the intake pressure IP.

Next, the relationship among the opening / closing operation of the exhaust valve 24, the in-cylinder pressure CP, and the exhaust pressure will be described with reference to FIG.
As shown in FIG. 3, when the exhaust stroke is started, the exhaust valve 24 is in a state where the valve lift amount VLe is larger than “0” from the closed state where the valve lift amount VLe is “0”, that is, opened. Transition to the valve state. Then, after the valve lift amount VLe becomes the maximum, the exhaust valve 24 becomes the valve lift amount VLe and becomes “0”, thereby closing the valve and completing the exhaust stroke. For example, in FIG. 3, the exhaust valve 24 starts the exhaust stroke from a crank angle smaller than 180 ° CA, and the valve lift amount VLe becomes maximum at 270 ° CA, and the exhaust stroke ends after 360 ° CA. To do. In this exhaust stroke, the in-cylinder pressure sensor 45 detects a pressure that largely fluctuates around the atmospheric pressure P 0 as the in-cylinder pressure CP in the combustion chamber 14. Further, in the same exhaust stroke, a test pressure sensor provided in a test in the exhaust passage 23 detects a pressure that largely fluctuates around the atmospheric pressure P0 as the exhaust pressure EP that is the pressure in the exhaust passage 23.

  That is, when the exhaust pressure EP and the in-cylinder pressure CP thus measured are compared in a range SE corresponding to the exhaust stroke, the exhaust pressure EP and the in-cylinder pressure CP are similar in value and variation. I understand that. The in-cylinder pressure CP may include abrupt fluctuations due to noise or the like. However, in the exhaust stroke, a process that regulates or smoothes such abrupt fluctuations with a filter is performed. The internal pressure CP can be made more similar to the exhaust pressure EP. For this reason, the ECU 41 of the present embodiment uses the in-cylinder pressure CP in place of the exhaust pressure EP of the exhaust passage 23 in the exhaust stroke. That is, the in-cylinder pressure CP is used as the estimated value of the exhaust pressure EP. The ECU 41 may use a value obtained by performing a predetermined process on the in-cylinder pressure CP as the estimated value of the exhaust pressure EP.

Next, the estimation of the intake pressure and the exhaust pressure in one cycle of the internal combustion engine 11 will be described with reference to FIGS.
In the internal combustion engine 11, since the three cylinders 12 of the bank share one intake passage 21 and the exhaust passage 23, the three cylinders 12 provided in the bank have an intake stroke phase of each cylinder 12. Each is shifted by 240 ° CA, and the exhaust stroke phase of each cylinder 12 is also shifted by 240 ° CA.

  That is, as shown in FIG. 4, in the bank, three first to third intake strokes I1, I2, and I3 corresponding to the three cylinders 12 are arranged in one cycle at equal crank angle intervals. For example, the first suction stroke I1 starts from 330 ° CA, reaches the maximum lift amount at 450 ° CA, and ends at 570 ° CA. The second suction stroke I2 starts from 570 ° CA, reaches the maximum lift at 690 ° CA, and ends at 90 ° CA of the next cycle. Further, the third suction stroke I3 starts from 90 ° CA, reaches the maximum lift at 210 ° CA, and ends at 330 ° CA.

  That is, in the intake passage 21, the first to third intake strokes I1, I2, and I3 are sequentially repeated every 240 ° CA. Therefore, the intake pressure IP of the intake passage 21 is changed from the first to third intake steps every 240 ° CA. The changes corresponding to the intake strokes I1, I2, and I3 are sequentially repeated.

  By the way, when the intake pressure IP of the intake passage 21 is measured for one cycle by the test pressure sensor, the intake pressures in the portions corresponding to the first to third intake strokes I1, I2, and I3 have their values and fluctuations, respectively. It can be seen that they are similar to each other. That is, it can be seen that the intake pressure data of the first intake stroke I1 can be used as the intake pressure data of the second and third intake strokes I2 and I3. Therefore, when the intake pressure in the intake passage 21 is estimated based on the in-cylinder pressure CP in the first intake stroke I1, the estimated intake pressure in the intake passage 21 is changed to the second intake stroke I2 or the second intake stroke I2. It can be seen that it can also be used as an estimated value of the intake pressure of the intake passage 21 in the third intake stroke I3. That is, since the repetition of the pressure waveform of the in-cylinder pressure CP based on the detection value of the in-cylinder pressure sensor 45 has a characteristic corresponding to the change in the intake pressure IP, by using this characteristic, the second or third It can be seen that the intake pressure IP corresponding to the intake strokes I2 and I3 can be estimated from the detection values of the in-cylinder pressure sensors 45 of the other cylinders.

  Therefore, in the present embodiment, the ECU 41 calculates the estimated value of the intake pressure IP of the intake passage 21 in the first intake stroke I1 based on the in-cylinder pressure CPi measured in the cylinder 12 corresponding to the first intake stroke I1. I try to estimate. Further, the ECU 41 uses the estimated value of the intake pressure IP of the intake passage 21 in the first intake stroke I1 as the estimated value of the intake pressure IP corresponding to the second and third intake strokes I2 and I3, that is, The estimation is based on the in-cylinder pressure CPi in the cylinder 12 corresponding to the first suction stroke I1. As described above, the ECU 41 performs the intake of the intake passage 21 in any period of the first to third intake strokes I1 to I3 based on the in-cylinder pressure CPi in the cylinder 12 corresponding to the first intake stroke I1. Estimate atmospheric pressure.

  Further, as shown in FIG. 5, in the bank, three first to third exhaust strokes E1, E2, E3 corresponding to the three cylinders 12 are arranged in one cycle at equal crank angle intervals. For example, the first exhaust stroke E1 starts at 150 ° CA, reaches the maximum lift amount at 270 ° CA, and ends at 390 ° CA. The second exhaust stroke E2 starts from 390 ° CA, reaches the maximum lift amount at 510 ° CA, and ends at 630 ° CA. Further, the third exhaust stroke E3 starts at 630 ° CA, reaches the maximum lift amount at the next 60 ° CA, and ends at 150 ° CA.

  That is, in the exhaust passage 23, the first to third exhaust strokes E1, E2, and E3 are sequentially repeated every 240 ° CA. Therefore, the exhaust pressure EP of the exhaust passage 23 is changed to the first to the second every 240 ° CA. Changes corresponding to the third exhaust strokes E1, E2, and E3 are sequentially repeated.

  By the way, when the exhaust pressure EP of the exhaust passage 23 is measured for one cycle with the test pressure sensor, the exhaust pressures corresponding to the first to third exhaust strokes E1, E2, E3 have their values and fluctuations mutually. You can see that they are similar. That is, it can be seen that the exhaust pressure data of the first exhaust stroke E1 can be used as the exhaust pressure data of the second and third exhaust strokes E2 and E3. From this, when the exhaust pressure in the exhaust passage 23 is estimated based on the in-cylinder pressure CP in the first exhaust stroke E1, the estimated exhaust pressure in the exhaust passage 23 is changed to the second exhaust stroke E2 or the second exhaust stroke E2. It can be seen that it can also be used as an estimated value of the exhaust pressure in the exhaust passage 23 in the third exhaust stroke E3. That is, since the repetition of the pressure waveform of the in-cylinder pressure CP based on the detection value of the in-cylinder pressure sensor 45 has a characteristic corresponding to the change in the exhaust pressure EP, the second and third characteristics can be obtained by using this characteristic. It can be seen that the exhaust pressure EP corresponding to the exhaust strokes E2 and E3 can be estimated from the detection values of the in-cylinder pressure sensors 45 of the other cylinders.

  Therefore, in the present embodiment, the ECU 41 calculates the estimated value of the exhaust pressure EP in the exhaust passage 23 in the first exhaust stroke E1 based on the in-cylinder pressure CPe measured in the cylinder 12 corresponding to the first exhaust stroke E1. I try to estimate. Further, the ECU 41 also uses the estimated value of the exhaust pressure EP of the exhaust passage 23 in the first exhaust stroke E1 for the estimated values of the exhaust pressure EP corresponding to the second and third exhaust strokes E2 and E3. The estimation is based on the in-cylinder pressure CPe in the cylinder 12 corresponding to the first exhaust stroke E1. As described above, the ECU 41 is configured to exhaust the exhaust passage 23 in any period of the first to third exhaust strokes E1 to E3 based on the in-cylinder pressure CPe in the cylinder 12 corresponding to the first exhaust stroke E1. Estimate atmospheric pressure.

(Function)
A procedure in which the ECU 41 estimates and outputs the intake pressure and the exhaust pressure will be described with reference to FIG. Note that the process of estimating and outputting the intake pressure and the exhaust pressure is sequentially executed by the ECU 41 in response to the request for the intake pressure and the exhaust pressure due to an internal request or an external request of the ECU 41. Here, as described above, only the in-cylinder pressure sensor 45 provided in one representative cylinder 12 selected from the three cylinders 12 in one bank is used for the intake pressure and exhaust pressure of the internal combustion engine 11. The case where it uses for estimation is demonstrated.

  When the ECU 41 is required to estimate and output the intake pressure or exhaust pressure, the crank angle CA, the open / close state of the intake valve 22, the open / close state of the exhaust valve 24 corresponding to the representative cylinder 12, and the cylinder of the representative cylinder 12 The internal pressure CP is acquired (step S11). The ECU 41 determines whether the exhaust valve 24 is open based on the acquired open / closed state of the exhaust valve 24 (step S12). When it is determined that the exhaust valve 24 is open, the ECU 41 employs the measured in-cylinder pressure CP as the exhaust pressure, that is, estimates the in-cylinder pressure CP as the exhaust pressure (step S13). On the other hand, when it is determined that the exhaust valve 24 is closed, the ECU 41 controls the exhaust pressure based on the in-cylinder pressure CP that is held in the memory or the like and is measured when the representative cylinder 12 is in the exhaust stroke. Estimate (step S14). More specifically, the fact that the exhaust valve 24 of the representative cylinder 12 is closed means that the other cylinders 12 are in the exhaust stroke. Therefore, the ECU 41 determines whether the representative cylinder 12 is held based on the phase difference (for example, 240 ° CA or 480 ° CA) between the cylinder 12 during the exhaust stroke and the exhaust stroke of the representative cylinder 12. The phase of the in-cylinder pressure CP is shifted. The exhaust pressure based on the influence of the cylinder 12 during the exhaust stroke is estimated based on the in-cylinder pressure CP of the representative cylinder 12 whose phase is shifted.

Then, the ECU 41 outputs the exhaust pressure estimated in step S13 or step S14 as the exhaust pressure of the exhaust passage 23 (step S15).
Subsequently, the ECU 41 determines whether the intake valve 22 is open based on the acquired opening / closing state of the intake valve 22 (step S16). When it is determined that the intake valve 22 is open, the ECU 41 employs the measured in-cylinder pressure CP as the intake pressure, that is, estimates the in-cylinder pressure CP as the intake pressure (step S17). On the other hand, when it is determined that the intake valve 22 is closed, the ECU 41 controls the intake pressure based on the in-cylinder pressure CP that is held in the memory or the like and is measured when the representative cylinder 12 is in the intake stroke. Estimate (step S18). More specifically, the fact that the intake valve 22 of the representative cylinder 12 is closed means that the other cylinders 12 are in the intake stroke. Accordingly, the ECU 41 determines whether the representative cylinder 12 that is held is based on the phase difference (for example, 240 ° CA or 480 ° CA) between the cylinder 12 during the intake stroke and the intake stroke of the representative cylinder 12. The phase of the in-cylinder pressure CP is shifted. The intake pressure based on the influence of the cylinder 12 during the intake stroke is estimated based on the in-cylinder pressure CP of the representative cylinder 12 whose phase is shifted.

Then, the ECU 41 outputs the intake pressure estimated in step S17 or step S18 as the intake pressure of the intake passage 21 (step S19).
Thereby, the estimation and output processing of the intake pressure and the exhaust pressure by the ECU 41 ends.

As described above, according to the state estimation device for an internal combustion engine of the present embodiment, the effects listed below can be obtained.
(1) Since the intake pressure and the exhaust pressure are estimated based on the pressure in the cylinder 12 during the opening period of the intake valve 22 and the exhaust valve 24, a pressure sensor is used to measure the intake pressure and the exhaust pressure. Is not required to be provided in the intake passage 21 or the exhaust passage 23. By doing so, the internal combustion engine state estimating apparatus can easily estimate the intake pressure and the exhaust pressure.

In addition, the intake air amount can be obtained from the intake pressure estimated by using a map that can obtain the intake air amount based on the intake pressure.
(2) Repetition of the pressure waveform based on the detection value of the in-cylinder pressure sensor 45 utilizes characteristics corresponding to changes in the intake pressure and the exhaust pressure, and the intake pressure and the exhaust pressure in one cycle are changed to the in-cylinder pressure sensor 45. It was made to estimate by the detected value. For example, if the intake valve 22 or the exhaust valve 24 is open, the detected value of the in-cylinder pressure sensor 45 can be used as an estimated value of the intake pressure or the exhaust pressure. Further, if the intake valve 22 and the exhaust valve 24 are closed, the detected value of the in-cylinder pressure sensor 45 is used to open the intake valves 22 and the exhaust valves 24 of the other cylinders 12. By corresponding during the period, at least one of the intake pressure and the exhaust pressure of the other cylinder 12 can be estimated. As a result, the number of pressure sensors necessary for measuring the intake pressure and the exhaust pressure can be reduced, and the number of in-cylinder pressure sensors 45 required for estimating the intake pressure and the exhaust pressure can be reduced. become able to.

  (3) Since the in-cylinder pressure sensor 45 is disposed on the side surface of the cylinder forming the cylinder 12 and at a position closer to the combustion chamber 14 than the top dead center TDC of the piston 13, the in-cylinder pressure sensor 45 is always in the cylinder. Since the pressure in the combustion chamber 14 partitioned inside can be measured, it is convenient for control of the internal combustion engine 11 such as obtaining continuous pressure data.

(Second Embodiment)
A second embodiment of the internal combustion engine equipped with the internal combustion engine state estimation apparatus according to the present invention will be described below with reference to FIG.

  The present embodiment is different from the first embodiment in that the in-cylinder pressure sensor 45A is arranged closer to the crankshaft 31 side than the in-cylinder pressure sensor 45 of the first embodiment. Since other configurations are the same, differences will be described below, and for convenience of explanation, the same numbers are assigned to the other configurations, and the configurations are omitted.

  As shown in FIG. 7, each cylinder 12 is provided with an in-cylinder pressure sensor 45A capable of measuring the pressure in the combustion chamber 14, that is, the so-called in-cylinder pressure. That is, the in-cylinder pressure sensor 45 </ b> A is arranged on the side surface of the cylinder forming the cylinder 12. The in-cylinder pressure sensor 45A is a pressure sensor that can detect the in-cylinder pressure in the intake stroke and the exhaust stroke with high accuracy, although the pressure resistance is lower than the in-cylinder pressure sensor 45 of the first embodiment. In the present embodiment, the in-cylinder pressure sensor 45A is on the side surface of the cylinder, and when the piston 13 is disposed at the top dead center TDC, the detection portion is covered with the side surface of the piston 13. That is, the detection part of the in-cylinder pressure sensor 45A is arranged at a position closer to the crankshaft 31 than at least one piston ring R1 arranged on the top dead center TDC side of the piston 13, and therefore the piston 13 is located on the upper side. When it is at the dead center TDC, it is isolated from the combustion chamber 14 by the piston ring R1. That is, the detection part of the in-cylinder pressure sensor 45A is provided at a position where the pressure in the combustion chamber 14 where the piston 13 is partitioned at the position of the top dead center TDC cannot be measured. For this reason, the in-cylinder pressure sensor 45A has a combustion chamber except for the front and rear ranges including the position where the piston 13 is at the top dead center TDC in the range from the top dead center TDC to the bottom dead center BDC where the piston 13 reciprocates. The pressure in 14 can be measured. On the other hand, in the present embodiment, the range before and after the position where the piston 13 is at the top dead center TDC is set as the non-measurable region Y, and the pressure in the combustion chamber 14 cannot be measured.

  As shown in FIGS. 8 and 9, the non-measurable region Y is formed in a range from 330 ° CA to 390 ° CA including 360 ° CA where the piston 13 becomes the top dead center TDC. Further, in the compression stroke and the expansion stroke, the non-measurable region Y is formed in a range from 690 ° CA to 30 ° CA including 720 ° CA (0 ° CA) where the piston 13 becomes the top dead center TDC.

Next, the opening / closing operation of the intake valve 22 and the estimation of the intake pressure based on the in-cylinder pressure will be described with reference to FIG.
The intake valve 22 starts the intake stroke from a crank angle smaller than 360 ° CA. When the intake valve 22 is 450 ° CA, the valve lift amount VLi becomes maximum, and the intake stroke ends after 540 ° CA. At this time, the in-cylinder pressure CP1i is measured. However, due to the influence of the non-measurable region Y, the in-cylinder pressure CP1i cannot be measured from 330 ° CA to 390 ° CA when the suction stroke is started. In the range SI1, the in-cylinder pressure CP1i having a value and change similar to the intake pressure IP is measured. That is, the intake pressure IP can be estimated based on the in-cylinder pressure CP1i. In the present embodiment, the in-cylinder pressure CP1i between 330 ° CA and 390 ° CA is supplemented by the in-cylinder pressure CP1e measured immediately before entering the unmeasurable region Y. For complementing the in-cylinder pressure in the non-measurable area Y, various complementing methods such as a method using immediately preceding data and a method using predetermined data can be used.

Next, the opening / closing operation of the exhaust valve 24 and the estimation of the exhaust pressure based on the in-cylinder pressure will be described with reference to FIG.
The exhaust valve 24 starts the exhaust stroke from a crank angle smaller than 180 ° CA. When the exhaust valve 24 is 270 ° CA, the valve lift amount VLe becomes maximum, and after 360 ° CA is passed, the exhaust stroke ends. At this time, the in-cylinder pressure CP1e is measured, but due to the influence of the unmeasurable region Y, the in-cylinder pressure CP1e cannot be measured from 330 ° CA to 390 ° CA before the exhaust stroke ends. In the range SE1 from 210 ° CA to 330 ° CA, the in-cylinder pressure CP1e having a value and change similar to the exhaust pressure EP is measured. That is, the exhaust pressure EP can be estimated based on the in-cylinder pressure CP1e. In the present embodiment, the in-cylinder pressure CP1e between 330 ° CA and 390 ° CA is supplemented by the in-cylinder pressure CP1e measured immediately before entering the unmeasurable region Y. For complementing the in-cylinder pressure in the non-measurable area Y, various complementing methods such as a method using immediately preceding data and a method using predetermined data can be used.

(Function)
In the compression / expansion stroke of the internal combustion engine 11, when the capacity of the combustion chamber 14 is minimized and the pressure in the combustion chamber 14 becomes high, and when the temperature becomes high due to combustion, the piston 13 causes the in-cylinder pressure sensor 45A to operate. By covering, the in-cylinder pressure sensor 45 </ b> A is temporarily isolated from the high pressure in the combustion chamber 14. As a result, the in-cylinder pressure sensor 45A can avoid high temperature and high pressure, particularly high temperature and high pressure peaks in the combustion chamber. That is, the in-cylinder pressure sensor 45A is less exposed to high temperatures and high pressures. This makes it possible to measure the in-cylinder pressure by providing the cylinder pressure sensor 45A with high accuracy in the cylinder 12, so that the intake pressure and exhaust pressure estimated from the measured in-cylinder pressure can be obtained with higher accuracy. Can be estimated.

  As described above, according to the state estimating device for an internal combustion engine of the present embodiment, in addition to the effects (1) and (2) described in the first embodiment, the effects listed below are obtained. Be able to.

  (4) In the compression / expansion stroke of the internal combustion engine 11, when the combustion chamber 14 becomes high temperature and high pressure due to combustion, that is, when the capacity of the combustion chamber 14 is minimized, the in-cylinder pressure sensor 45 </ b> A is covered by the piston 13 and burns. Temporarily isolated from chamber 14. As a result, the in-cylinder pressure sensor 45A can avoid high temperatures and high pressures in the combustion chamber 14, particularly high temperature and high pressure peaks. That is, the chance that the in-cylinder pressure sensor 45A is exposed to high temperature and high pressure can be reduced. As a result, the pressure resistance of the in-cylinder pressure sensor 45A can be lowered. Usually, since the measurement range of the in-cylinder pressure sensor 45A and the pressure resistance are in a proportional relationship, a sensor with a high pressure resistance has a wide measurement range, but the measurement accuracy is low, but the measurement range is narrowed by reducing the pressure resistance. As a result, the measurement accuracy in the measurement range necessary for estimating the intake pressure and the exhaust pressure can be increased. In this case, there is a range where the in-cylinder pressure sensor 45A cannot measure the pressure in the range in which the intake pressure or the exhaust pressure is estimated. You may make it complement by various complementation processes, such as maintaining a pressure at the last measurement pressure. As a result, cost reduction by reducing the pressure resistance of the in-cylinder pressure sensor 45A employed in the state estimation device for the internal combustion engine 11, maintenance of reliability due to suppression of failures due to high pressure, and the like. Improvement of the design freedom of the mounting position can be achieved.

(Other embodiments)
In addition, each said embodiment can also be implemented in the following aspects, for example.
-As an internal combustion engine of each said embodiment, a gasoline engine, a diesel engine, etc. are suitable. Thereby, the application range of the state estimation device for the internal combustion engine can be expanded.

  -An exhaust gas recirculation apparatus (EGR apparatus) may be provided in the internal combustion engine of each said embodiment. For example, as shown in FIG. 10, in an internal combustion engine 11 provided with an EGR device, intake air supplied to the combustion chamber 14 by a throttle valve 20A whose opening is adjusted by a throttle motor (not shown) is provided in an intake passage 21. Adjust the amount. The intake passage 21 is provided with a fuel injection valve 15 that injects fuel into the intake port 21a. Further, one end of an exhaust gas recirculation passage 33 for introducing a part of the exhaust gas flowing through the exhaust passage 23 into the intake passage 21 is connected to the downstream side of the throttle valve 20A in the intake passage 21. The exhaust gas recirculation passage 33 is provided with an exhaust gas recirculation valve 35 that adjusts the flow rate of the exhaust gas flowing through the exhaust gas recirculation passage 33 and an EGR cooler 36 that cools the exhaust gas recirculated to the intake air passage 21. On the other hand, an exhaust gas purification device 28 is provided in the exhaust passage 23. The exhaust purification device 28 carries a three-way catalyst for purifying hydrocarbons HC, carbon monoxide CO, and nitrogen oxides NOx contained in the exhaust. Further, in the exhaust passage 23, the other end of the exhaust gas recirculation passage 33 is connected to a portion upstream of the exhaust purification device 28. When the exhaust gas recirculation valve 35 provided in the exhaust gas recirculation passage 33 is opened, the exhaust gas upstream of the exhaust gas purification device 28 in the exhaust passage 23 is recirculated to the intake air passage 21 through the exhaust gas recirculation passage 33. .

  In general, the internal combustion engine 11 provided with the EGR device calculates the amount of external EGR, which is the exhaust gas recirculated to the intake air, from the exhaust pressure, the intake air pressure, the exhaust gas temperature, and the exhaust gas recirculation valve 35 opening degree. Intake pressure or exhaust pressure can be used. In addition, the internal combustion engine 11 provided with the EGR device has a tendency that the fluctuations in the intake pressure and the exhaust pressure tend to increase, for example, the pulsation tends to occur in the intake pressure and the exhaust pressure. Based on the estimation of the intake pressure and the exhaust pressure based on this, engine control including adjustment of the opening degree of the exhaust gas recirculation valve 35 can be suitably performed even if the number of pressure sensors is reduced.

  In the first embodiment, the case where the in-cylinder pressure sensor 45 is provided on the side surface of the cylinder forming the cylinder 12 is illustrated. However, the present invention is not limited to this, and the in-cylinder pressure sensor may be provided at a position other than the side surface of the cylinder, such as the cylinder head, as long as the in-cylinder pressure can be measured. Thereby, the degree of freedom of the arrangement position of the in-cylinder pressure sensor is increased, and the applicability of the internal combustion engine state estimation device can be improved.

  In the first embodiment, a plurality of intake strokes I1, I2, and I3 and a plurality of exhaust strokes E1, E2, and E3 are arranged at equal intervals of 240 ° CA in one cycle (720 ° CA). The case was illustrated. However, the present invention is not limited to this, and a plurality of intake strokes or a plurality of exhaust strokes may not be arranged at equal intervals in one cycle. Thereby, the applicability of the state estimation device for the internal combustion engine can be expanded.

  In the first embodiment, the intake pressure in the second or third intake stroke I2, I3 is estimated based on the in-cylinder pressure in the combustion chamber 14 of the cylinder 12 corresponding to the first intake stroke I1. Illustrated. However, the present invention is not limited to this, and the intake pressure in the intake passage corresponding to the first to third intake strokes is similar to each other. Therefore, the pressure measured in the combustion chamber of the cylinder corresponding to the second intake stroke I2 May be used to estimate the intake pressure in the first or third intake stroke. Alternatively, the intake pressure in the first or second intake stroke may be estimated based on the pressure measured in the combustion chamber of the cylinder corresponding to the third intake stroke I3.

  In the first embodiment, the exhaust pressure in the second or third exhaust stroke E2, E3 is estimated based on the in-cylinder pressure in the combustion chamber 14 of the cylinder 12 corresponding to the first exhaust stroke E1. Illustrated. However, the present invention is not limited to this, and the exhaust pressures in the exhaust passages corresponding to the first to third exhaust strokes are similar to each other. Therefore, the pressure measured in the combustion chamber of the cylinder corresponding to the second exhaust stroke E2 May be used to estimate the exhaust pressure in the first or third exhaust stroke. Alternatively, the exhaust pressure in the first or second exhaust stroke may be estimated based on the pressure measured in the combustion chamber of the cylinder corresponding to the third exhaust stroke E3.

  In the first embodiment, the intake pressure of the intake passage 21 connected to the three cylinders and the exhaust pressure connected to the exhaust passage 23 are estimated based on the repetition of the in-cylinder pressure CP of one cylinder. However, such estimation may not be performed. For example, if each cylinder is provided with an in-cylinder pressure sensor, the intake pressure and the exhaust pressure can be estimated based on the in-cylinder pressure sensor of each cylinder in the intake stroke and the exhaust stroke of each cylinder.

  In the first embodiment, the case where the cylinder pressure sensors 45 and 45A are provided in each cylinder 12 is illustrated. However, the present invention is not limited to this, and in the case of multiple cylinders, an in-cylinder pressure sensor may be provided in a representative cylinder including, for example, one cylinder, which is a part of the cylinder sharing the intake passage. In this case, the intake pressure estimated from the in-cylinder pressure sensor of the cylinder in the intake stroke of the representative cylinder may be estimated as the intake pressure in the intake stroke of the other cylinders. Similarly, in the case of multiple cylinders, an in-cylinder pressure sensor may be provided in a representative cylinder that is a part of a cylinder that shares an exhaust passage, for example, a single cylinder. In this case, the exhaust pressure estimated from the in-cylinder pressure sensor of the cylinder in the exhaust stroke of the representative cylinder may be estimated as the exhaust pressure in the exhaust stroke of the other cylinder. As a result, the number of in-cylinder pressure sensors provided in the internal combustion engine as well as pressure sensors for measuring the intake pressure and the exhaust pressure can be further reduced.

  In each of the above embodiments, the estimated intake pressure or exhaust pressure is used for engine control. However, the present invention is not limited to this, and the intake pressure and the exhaust pressure may be used for the other engine control and other control described above. For example, when a turbocharger that is a supercharger is provided in the internal combustion engine, the turbocharger flow rate may be calculated based on the intake pressure or the exhaust pressure estimated based on the in-cylinder pressure. Further, the clogging of the catalyst for purifying the exhaust component provided in the exhaust passage may be determined based on the exhaust pressure estimated based on the in-cylinder pressure. Furthermore, it is possible to determine whether or not the diesel particulate filter (DPF) that collects particulate matter (PM) in the exhaust provided in the exhaust passage based on the exhaust pressure estimated based on the in-cylinder pressure is clogged. Good.

  In each of the above embodiments, the internal combustion engine 11 is illustrated as a so-called port injection in which a mixture of intake air and injected fuel is sucked into the combustion chamber 14. It may be so-called direct injection in which fuel is directly injected into the room, or a combination of port injection and direct injection. As a result, the application range of the internal combustion engine state estimation device can be expanded.

  In each of the above-described embodiments, the case where the internal combustion engine is a V-type 6-cylinder engine is illustrated. However, the present invention is not limited thereto, and the internal combustion engine may be 2, 3, 4, 5 even if the number of cylinders is a single cylinder. There may be more cylinders than cylinders or six cylinders. Further, the cylinder arrangement may be an arrangement other than the V type such as a series type, a parallel type, and a horizontally opposed type. As a result, the pressure sensor for measuring the intake pressure and the exhaust pressure can be reduced regardless of the number of cylinders and the cylinder arrangement of the internal combustion engine, so that the application range of the state estimation device for the internal combustion engine can be expanded. become.

  For example, in the case of an in-line multi-cylinder engine, as a cylinder representing one of a plurality of cylinders, an in-cylinder pressure sensor of the representative cylinder is used for estimation of intake pressure or exhaust pressure, or only a representative cylinder is used. An in-cylinder pressure sensor may be provided. Thus, regardless of the number of cylinders and the cylinder arrangement of the internal combustion engine, the state estimation device for the internal combustion engine can also reduce the in-cylinder pressure sensor provided in the cylinder.

  DESCRIPTION OF SYMBOLS 11 ... Internal combustion engine, 12 ... Cylinder, 13 ... Piston, 14 ... Combustion chamber, 15 ... Fuel injection valve, 16 ... Spark plug, 20A ... Throttle valve, 21 ... Intake passage, 21a ... Intake port, 22 ... Intake valve, 23 DESCRIPTION OF SYMBOLS ... Exhaust passage, 23a ... Exhaust port, 24 ... Exhaust valve, 26 ... Intake camshaft, 27 ... Exhaust camshaft, 28 ... Exhaust purification device, 31 ... Crankshaft, 33 ... Exhaust recirculation passage, 35 ... Exhaust recirculation valve, 36 ... EGR cooler, 41 ... ECU (electronic control unit), 42 ... Crank position sensor, 43 ... Intake cam position sensor, 44 ... Exhaust cam position sensor, 45, 45A ... In-cylinder pressure sensor, 46 ... Shift position sensor, 47 ... Accelerator position sensor, 48 ... Brake sensor, 49 ... Vehicle speed sensor, P0 ... Atmospheric pressure, BDC ... Bottom dead , TDC ... top dead center.

Claims (6)

In-cylinder pressure sensor that measures the pressure in the cylinder,
Based on the detected value of the in-cylinder pressure sensor during the opening period of the intake valve that opens and closes the intake port of the cylinder and the exhaust valve that opens and closes the exhaust port of the cylinder, at least the intake pressure and the exhaust pressure of the internal combustion engine An internal combustion engine state estimation device characterized in that one of the states is estimated as an engine state. 2. The internal combustion engine according to claim 1, wherein a pressure in an arbitrary period of at least one of the intake pressure and the exhaust pressure is estimated as an engine state using a repetitive characteristic of a pressure waveform based on a detection value of the in-cylinder pressure sensor. State estimation device. 3. The internal combustion engine according to claim 1, wherein the in-cylinder pressure sensor is disposed on a side surface of the cylinder forming the cylinder, and is disposed at a position closer to the combustion chamber than the top dead center of the piston. State estimation device. 3. The cylinder pressure sensor according to claim 1, wherein the cylinder pressure sensor is disposed on a side surface of the cylinder forming the cylinder and is covered with the piston when the piston reaches top dead center. An internal combustion engine state estimation device. 5. The internal combustion engine according to claim 1, wherein the internal combustion engine is a V-type multi-cylinder engine, and the in-cylinder pressure sensor is provided for one representative cylinder for each bank. State estimation device. The internal combustion engine state estimation device according to any one of claims 1 to 4, wherein the internal combustion engine is an in-line multi-cylinder engine, and the in-cylinder pressure sensor is provided for one representative cylinder.

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