JP4863010B2 - Combustion control device for internal combustion engine - Google Patents

Description

  The present invention relates to a combustion control device for an internal combustion engine, and is intended to reduce the accumulation of residual solid components that are solid components of soot and oil remaining in a combustion chamber when operated at a low combustion temperature. .

  In particular, the present invention relates to an internal combustion engine provided with intake flow control means for controlling the flow of intake air flowing into the combustion chamber by opening and closing the exhaust gas recirculation means and the intake passage, and the exhaust gas is exhausted when the intake passage is closed. In a state where the amount of gas reflux is increased, that is, in a state where the combustion temperature is low and soot and oil solid components are likely to remain, soot accumulation in the combustion chamber is reduced. It is a thing.

  As a device for reducing nitrogen oxide (NOx) in exhaust gas, an exhaust gas recirculation device (EGR device) that recirculates part of exhaust gas from an internal combustion engine (engine) to an intake system is known. The EGR device includes an EGR passage that communicates an intake passage and an exhaust passage to introduce exhaust gas into the intake passage, and controls the recirculation amount of exhaust gas according to the operating state of the engine by opening and closing the EGR passage with an EGR valve. (For example, refer to Patent Document 1 below).

  On the other hand, an intake control device is known that controls the flow of intake air flowing into a combustion chamber of an engine to generate a rotational flow (tumble flow) in the intake air in the combustion chamber to promote fuel combustion. The intake control device is provided with a flow control valve (intake flow control valve) in the intake passage. For example, by closing the lower portion of the intake passage with the intake flow control valve, the intake air is biased and circulated upward in the intake passage. A tumble flow is generated (see, for example, Patent Document 2 below).

  It is known that when the intake passage is closed by the intake flow control valve, even if the EGR passage is opened and a large amount of exhaust gas is introduced into the intake passage, the combustion fluctuation does not deteriorate and the fuel efficiency is improved. That is, by increasing the EGR rate and introducing a large amount of exhaust gas while the intake flow control valve is closed, it is possible to improve fuel efficiency without deteriorating combustion.

  When the engine operation is repeated at a low combustion temperature, for example, when the operation is repeated until the warm-up operation is completed, the residual solid component (combustion chamber deposit) which is a solid component of soot and oil Tends to accumulate in the combustion chamber of the engine. If the ratio of the exhaust gas recirculated by the EGR device increases, the amount of combustion chamber deposits may increase. In particular, in an engine equipped with an intake control device, a large amount of exhaust gas is introduced by increasing the EGR rate while the intake flow control valve is closed. The amount of deposits tends to increase.

JP 2007-32315 A JP 2004-293484 A

  The present invention has been made in view of the above situation, and even when operated under conditions of low combustion temperature, residual solid components (combustion chamber deposits) that are solid components of soot and oil remaining in the combustion chamber An object of the present invention is to provide a combustion control device for an internal combustion engine that can reduce deposition.

In order to achieve the above object, a combustion control device for an internal combustion engine according to claim 1 of the present invention has an operation region per unit period of a combustion chamber of the internal combustion engine of at least a low temperature combustion region having a low combustion temperature and a high temperature having a high combustion temperature. A combustion temperature detecting means for detecting or estimating which one of the plurality of combustion areas including the combustion area, a temperature raising measure means for raising the combustion temperature of the combustion chamber of the internal combustion engine, and the temperature raising measure means are operated. Combustion control means, wherein the combustion control means integrates the outputs of the combustion temperature detection means to obtain the ratio of the plurality of combustion areas, and the ratio of the low temperature combustion area increases based on the obtained ratio Then, a coefficient that increases and decreases as the ratio of the high-temperature combustion region increases is calculated. When the coefficient exceeds a predetermined value, the temperature raising measure means is operated.

  In the present invention according to claim 1, the combustion temperature of the combustion chamber of the internal combustion engine that affects the accumulation of residual solid components is detected or estimated, and when the combustion temperature continues to be low or the combustion temperature is high Sometimes, the internal combustion engine is operated so that the combustion temperature in the combustion chamber rises by the temperature raising measure means, and the amount of accumulated solid components can be reduced while taking into account the fuel efficiency.

  Preferably, the temperature raising measure means is operated when the operation ratio in the low temperature combustion region exceeds a predetermined value. According to this configuration, in consideration of the increase in the amount of residual solid component accumulation due to operation in the low-temperature combustion region and the decrease in the amount of residual solid component accumulation due to operation in the high-temperature combustion region, Can be suppressed.

Combustion control device for an internal combustion engine of the present invention according to claim 2, before Symbol combustion control means, when the coefficient after operation of the heating measures means is less than another predetermined value for stopping the combustion temperature rise If it is determined, the temperature raising measure means is stopped.

  In the present invention according to claim 2, when the combustion temperature continues to be high or when the combustion temperature is low, the operation of the temperature raising measure means is stopped, and the continued operation of the excessive temperature raising measure means is suppressed. can do.

  Preferably, the operation of the temperature raising measure means is stopped when the operation in the high temperature combustion region reaches a predetermined value. According to this configuration, since the residual solid component is basically hardly deposited during the operation of the temperature raising measure means, the control can be simplified by considering only the high temperature combustion region.

Combustion control device for an internal combustion engine of the present invention according to claim 3, before Symbol combustion temperature detecting means, said plurality of based average value of the engine speed of the internal combustion engine per between unit period and the average value of the load characterized that you detecting or estimating which of regions.

  In the third aspect of the present invention, the combustion temperature can be easily detected based on the engine speed and the load. For example, a low rotation / low load region can be set as a low temperature combustion region, and a high rotation / high load can be set as a high temperature combustion region, and the combustion temperature of the unit period can be obtained based on the average engine speed and the average load of the unit period.

  Preferably, the unit period is from start to stop of the internal combustion engine. According to this configuration, it is not necessary to frequently detect the average engine speed, the average load, and the combustion temperature, and the combustion temperature in the combustion chamber can be detected, so that the amount of residual solid components deposited can be obtained.

  A combustion control apparatus for an internal combustion engine according to a fourth aspect of the present invention is the combustion control device according to any one of the first to third aspects, wherein the temperature raising measure means is means for reducing the amount of exhaust gas recirculated by the exhaust gas recirculation means, It is at least one of means for advancing the ignition timing and means for increasing the coolant temperature of the internal combustion engine.

  In the present invention according to claim 4, the EGR rate is lowered to reduce the exhaust amount to be recirculated, thereby suppressing a decrease in the combustion temperature. The ignition timing is advanced to increase the maximum pressure to raise the position of the maximum pressure. The combustion temperature can be raised by at least one means of raising the combustion temperature by approaching the dead center and raising the combustion temperature by raising the cooling water temperature.

  The combustion control apparatus for an internal combustion engine according to the present invention deposits residual solid components (combustion chamber deposits), which are solid components of soot and oil remaining in the combustion chamber, even when operated at a low combustion temperature. Can be reduced.

  In particular, in an internal combustion engine provided with intake flow control means for controlling the flow of intake air flowing into the combustion chamber by opening and closing the exhaust gas recirculation means and the intake passage, the recirculation amount of the exhaust gas when the intake passage is closed In other words, the accumulation of combustion chamber deposits remaining in the combustion chamber can be reduced in a state where the combustion temperature is low, that is, in a state where the combustion temperature is low and solid components of soot and oil tend to remain.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The internal combustion engine of the following embodiment is an intake pipe injection type multi-cylinder (for example, 4-cylinder) gasoline engine. Also, a gasoline engine provided with an exhaust gas recirculation device (EGR device) that recirculates part of the exhaust gas to the intake system and an intake air control device having a flow control valve (intake flow control valve) in the intake passage is illustrated.

  As the internal combustion engine, not only a multi-cylinder gasoline engine but also an in-cylinder injection gasoline engine, a diesel engine, or the like can be applied. It is also possible to apply an internal combustion engine that does not include an EGR device and an intake air control device.

  1 is a schematic configuration of a combustion control apparatus for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a control flowchart for setting an operating region, FIG. 3 is a combustion temperature control flowchart, and FIG. Is a map for setting the operation region, FIG. 5 is a graph showing the relationship between the combustion temperature and the EGR rate, FIG. 6 is a graph showing the relationship between the combustion temperature and the ignition timing, and FIG. 7 is a combustion temperature and cooling. A graph showing the relationship with water temperature is shown.

  Based on FIG. 1, the structure of the combustion control apparatus of an internal combustion engine is demonstrated.

  As shown in the drawing, an ignition plug 3 is attached to each cylinder head 2 of an engine main body (hereinafter referred to as an engine) 1 which is an internal combustion engine (engine), and an ignition that outputs a high voltage to the ignition plug 3. The coil 4 is connected. An intake port 5 is formed in the cylinder head 2 for each cylinder, and an intake valve 7 is provided on the combustion chamber 6 side of each intake port 5. The intake valve 7 is opened and closed in accordance with a cam of a camshaft (not shown) that rotates according to the engine rotation, so that the intake ports 5 and the combustion chambers 6 are communicated and blocked.

  One end of an intake manifold 9 is connected to each intake port 5, and the intake manifold 9 communicates with each intake port 5. An electromagnetic fuel injection valve (injection) 10 is attached to the intake manifold 9, and fuel is supplied from the fuel tank to the fuel injection valve 10 through a fuel pipe.

  Further, an exhaust port 11 is formed in the cylinder head 2 for each cylinder, and an exhaust valve 12 is provided on the combustion chamber 6 side of each exhaust port 11. The exhaust valve 12 is opened and closed following a cam of a camshaft (not shown) that rotates in accordance with engine rotation, so that each exhaust port 11 and the combustion chamber 6 are communicated and blocked. One end of an exhaust manifold 13 is connected to each exhaust port 11, and the exhaust manifold 13 communicates with each exhaust port 11.

  In addition, since such an engine is a well-known thing, it abbreviate | omitted about the detail of the structure.

  An intake pipe 14 (intake passage) is connected to the intake manifold 9 on the upstream side of the fuel injection valve 10, and an electromagnetic throttle valve 15 is attached to the intake pipe 14 to detect the valve opening of the throttle valve 15. A position sensor 16 is provided. An air flow sensor 17 for measuring the intake air amount is provided on the upstream side of the throttle valve 15. As the air flow sensor 17, a Karman vortex type or hot film type air flow sensor is used. A surge tank 18 is provided in the intake pipe 14 between the intake manifold 9 and the throttle valve 15.

  An exhaust pipe 20 is connected to the other end of the exhaust manifold 13, and an exhaust gas circulation port (EGR port) 21 is branched to the exhaust manifold 13. One end of an EGR pipe 22 is connected to the EGR port 21, and the other end of the EGR pipe 22 is connected to the intake pipe 14 upstream of the surge tank 18. An EGR valve 23 is provided in the EGR pipe 22 close to the surge tank 18, and a part of the exhaust gas is introduced into the intake pipe 14 upstream of the surge tank 18 through the EGR pipe 22 by opening the EGR valve 23. Is done.

  That is, the EGR pipe 22 and the EGR valve 23 constitute exhaust gas recirculation means (EGR device). The EGR device recirculates a part of the exhaust gas to the intake system (surge tank 18) of the engine 1, lowers the combustion temperature in the combustion chamber 6 of the engine 1, and reduces the emission amount of nitrogen oxides (NOx). When the EGR valve 23 is opened and closed, a part of the exhaust gas is recirculated to the intake system as EGR gas at a predetermined EGR rate according to the opening degree.

  On the other hand, the intake manifold 9 is provided with a flow control valve (intake flow control valve) 25, and the intake flow control valve 25 is opened and closed by an actuator 26 such as a negative pressure actuator. The intake flow control valve 25 is composed of an open / close valve such as a butterfly valve or a shutter valve, and as shown in the figure, opens and closes the lower half of the intake passage. That is, by closing the intake flow control valve 25, an opening is formed on the upper side of the cross section of the intake passage, and a vertical tumble flow is generated inside the combustion chamber 6 by narrowing the cross sectional area of the intake passage. ing.

  The ECU (electronic control unit) 31 includes an input / output device, a storage device (ROM, RAM, etc.), a central processing unit (CPU), a timer counter, and the like. The ECU 31 performs comprehensive control of the combustion control device including the engine 1, the EGR valve 23, and the intake flow control valve 25.

  On the input side of the ECU 31, there are various types such as the TPS 16, the air flow sensor 17, the crank angle sensor 32 that detects the engine crank angle and obtains the engine rotation speed (Ne), and the water temperature sensor 33 that detects the cooling water temperature of the engine 1. Sensors are connected, and detection information from these sensors is input.

  On the other hand, various output devices such as the fuel injection valve 10, the ignition coil 4, the throttle valve 15, the EGR valve 23, and the actuator 26 of the intake flow control valve 25 are connected to the output side of the ECU 31. These various output devices include a fuel injection amount, a fuel injection time, an ignition timing, an operation timing / operation amount of the EGR valve 23, and an operation timing of the intake flow control valve 25 calculated by the ECU 31 based on detection information from various sensors. Etc. are output respectively.

  Based on detection information from various sensors, the air-fuel ratio is set to an appropriate target air-fuel ratio, an amount of fuel corresponding to the target air-fuel ratio is injected from the fuel injection valve 10 at an appropriate timing, and the throttle valve 15 is set appropriately. The spark opening is adjusted at an appropriate timing by the spark plug 3.

  Further, the rotational speed (Ne) and the load of the engine 1 are obtained based on the detection information from the crank angle sensor 32 and the like, and the intake flow control valve 25 is controlled to open and close in accordance with the rotational speed (Ne) and the load. The strength of the tumble flow of the intake air can be switched. For example, the intake flow control valve 25 is closed when the engine 1 is low and the load is low, and the tumble flow is strengthened to improve the combustibility, and the intake flow control valve 25 is opened and the intake air is high and the load is high. High output is secured by suppressing the rise of flow resistance.

  Further, the EGR rate is set according to the speed (Ne) of the engine 1 and the load, and the EGR valve 23 is opened / closed so as to reach a predetermined EGR rate, and a part of the exhaust gas is taken into the intake system (surge tank) of the engine 1. 18), the combustion temperature in the combustion chamber 6 of the engine 1 is lowered, and the emission amount of nitrogen oxides (NOx) is reduced. In particular, when the intake flow control valve 25 is closed and the tumble flow is strengthened when the engine 1 is running at a low speed and a low load, the combustion is improved, the combustion is stable, and the combustion fluctuation hardly occurs. A part of the fuel is introduced to improve fuel efficiency.

  If the engine is repeatedly operated at a low combustion temperature, for example, if the engine is repeatedly operated for a short time until the warm-up operation is completed, or if the ignition timing is retarded (retarded), Residual solid components (combustion chamber deposits), which are solid components, tend to accumulate in the combustion chamber of the engine. If the ratio of the exhaust gas recirculated by the EGR device increases, the amount of combustion chamber deposits may increase. In particular, in an engine equipped with an intake air control device, a large amount of exhaust gas is introduced by increasing the EGR rate while the intake air flow control valve is closed. The amount of deposits tends to increase.

  In the engine 1 of the present embodiment, the combustion temperature is estimated based on the rotational speed (Ne) of the engine 1 and the load (combustion temperature detection means), and when the ratio of the operation region where the combustion temperature is low exceeds a predetermined ratio. Assuming that the combustion chamber deposit has increased, a measure for raising the combustion temperature (temperature raising measure means) is implemented to raise the combustion temperature in the combustion chamber 6 (operation of the temperature raising measure means: combustion control means).

  The measures to increase the combustion temperature are to reduce the exhaust gas recirculation amount (decrease the EGR rate) and to suppress the decrease in the combustion temperature, or to advance the ignition timing and increase the maximum pressure to increase the position of the maximum pressure. Increasing the combustion temperature by approaching the top dead center, or increasing the combustion temperature by increasing the cooling water temperature is performed.

  In addition to the measures for raising the combustion temperature, various measures can be taken as long as the combustion temperature in the combustion chamber 6 is raised, such as adjusting the control parameter of the engine 1 to change the combustion temperature. Is possible.

  For this reason, in an operating state where the ratio of the operating region where the combustion temperature is low is large, the engine 1 is operated so that the combustion temperature rises, and the EGR rate is increased with the intake flow control valve closed to increase the amount of exhaust. Even when soot and the like are likely to remain in the combustion chamber 6 after being introduced, it is possible to accurately perform the operation in a state where the combustion chamber deposit of the combustion chamber 6 is difficult to accumulate. As a result, even when the engine 1 that can increase the EGR rate and improve the fuel efficiency with the intake flow control valve closed is operated under a low combustion temperature condition, the combustion chamber deposit of the combustion chamber 6 Therefore, it is possible to achieve both suppression of combustion chamber deposit and improvement of fuel consumption.

  Details of the processing of the combustion control device described above will be described with reference to FIGS.

  The state of the operation region is verified by the process shown in FIG. 2, and the combustion temperature increasing process corresponding to the state of the operation region is executed by the process shown in FIG.

  As shown in FIG. 4, three operating regions A, B, and C are set according to the rotational speed (Ne) and load (Load) of the engine 1, and the combustion region A is low (low temperature) on the low load / low rotation side. Combustion region), C region (high temperature combustion region) where combustion temperature is high on the high load / high rotation side, and intermediate B region. The map of the region shown in FIG. 4 can be different depending on the open / close state of the intake flow control valve. For example, since the tumble flow is promoted when the intake flow control valve is closed, the boundary between the operation region A and the operation region B is shifted to the low load / low rotation side, and the operation region B and the operation region C Similarly, the boundary can be shifted to the low load / low rotation side.

  In the process of FIG. 2, it is determined in which region the average rotation speed (average Ne) and the average load (average load) in one cycle (one trip) from the start to the stop of the engine 1 as a unit period are. Then, a process of adding (up) the counter of each area is executed. In the process of FIG. 3, it is determined that the vehicle has traveled a predetermined distance for a predetermined period in a state where the process of FIG. 2 is repeated, and the ratio of each region where the combustion temperature is different is obtained. When the ratio of the A region where the combustion temperature is low is large, a process for taking a measure for raising the combustion temperature is executed.

  The operation region verification process will be described with reference to FIG.

  As shown in the figure, when the process is started, information on the rotational speed (Ne) / load (Load) of the engine 1 is read in Step S1, and the current Ne (n) and the current Load (Current) are read in Step S2 and Step S3. n) is set.

In step S2, the value obtained by multiplying the previous Ne (n-1) by the coefficient k and the value obtained by multiplying Ne, which is the instantaneous rotational speed, by (1-k) are added, and the current rotation is calculated by the following equation. The speed Ne (n) is set. That is, Ne (n) averaged by the soft filter process is set.
Ne (n) = (1-k) * Nes + k * Ne (n-1)

In step S3, the value obtained by multiplying the previous load (n-1) by the coefficient k and the value obtained by multiplying the load, which is the instantaneous load, by (1-k) are added. A certain Load (n) is set. That is, Load (n) averaged by the soft filter process is set.
Load (n) = (1−k) * Loads + k * Load (n−1)

  Whether or not the current Ne (n) is set in step S2 and the current Load (n) is set in step S3 and then one cycle (one trip) from the start to the stop of the engine 1 is completed in step S4. Is judged. If it is determined in step S2 that one trip has not been completed (No), the processes from step S1 to step S3 are repeated until one trip is completed.

  If it is determined in step S2 that one trip has been completed (Yes), it is determined in step S5 which region is Ne (n) and Load (n) averaged over one trip. That is, it is determined where Ne (n) and Load (n) averaged during one trip are located in the operation areas A, B, and C shown in FIG.

  After the area is determined in step S5, it is determined in step S6 whether or not the determined area is the A area. If it is determined in step S6 that the area is (Yes), the A area is determined in step S7. The counter (Ca) is increased. If it is determined in step S6 that it is not the A area (No), it is determined in step S8 whether or not the determined area is the B area. If it is determined in step S8 that the area is the B area (Yes), the B area counter (Cb) is incremented in step S9. If it is determined in step S8 that the region is not the B region (No), the region based on Ne (n) and Load (n) averaged during one trip is the C region, so in step S10 the C region counter Increase (Cc).

  As a result, the operation during one trip becomes the A region where the combustion temperature is low on the low load / low rotation side, the C region where the combustion temperature is high on the high load / high rotation side, or the intermediate B region. It is determined whether or not the counter of any region is increased. In the process of FIG. 2, the area of driving in one trip is counted until the vehicle travels a predetermined distance.

  Based on FIG. 3, the process of the measure for raising the combustion temperature will be described.

  As shown in the figure, when the process is started, it is determined in step S11 whether or not the vehicle has traveled a predetermined distance 2 in the combustion temperature increasing process state. Since the combustion temperature raising process is not performed at first (No), the process proceeds to step S12. In step S12, it is determined whether or not the vehicle has traveled the predetermined distance 1. If it is determined in step S12 that the vehicle has not traveled the predetermined distance 1 (No), a return is made (R). If it is determined in step S12 that the vehicle is traveling the predetermined distance 1 (Yes), the values of the counters Ca, Cb, and Cc are added in step S13 to obtain the count value integration T. After obtaining the count value integration T in step S13, the ratio of each region is obtained in step S14. Note that the predetermined distance 1 <the predetermined distance 2 is set.

  That is, the ratio of Ca to the count value integration T (Ca / T) is set as the ratio A of the A region, the ratio of Cb to the count value integration T (Cb / T) is set as the ratio Br of the B region, and the count value is integrated. The ratio of Cc to T (Cc / T) is defined as the ratio Cr of the C region. As a result, within the entire operation range within the predetermined travel distance (within the count value integration T), how much each of the A region where the combustion temperature is low, the C region where the combustion temperature is high, and the intermediate B region exist. And a situation where the combustion temperature at a predetermined travel distance is low. That is, the status of the combustion chamber deposit is derived.

  After the ratio of each region is obtained in step S14, it is determined in step S15 whether or not the combustion temperature increase flag is ON, and whether or not a flag for executing the treatment is set with the condition for increasing the combustion temperature set. Is judged. At first, since it is determined that the combustion temperature increase flag is not ON (No), the process proceeds to step S16 to set a coefficient K for increasing the combustion temperature.

  The coefficient K is obtained by multiplying the ratio Ar of the A region where the combustion temperature is low by the weighting factor Wa, the value of multiplying the ratio Cr of the C region where the combustion temperature is high and the weighting factor Wc, and the ratio Br of the intermediate B region. It is calculated by adding the value multiplied by the weighting factor Wb. The weighting factors Wa, Wb, Wc are appropriately set according to the secular change of the engine 1, the total travel distance, the driving situation, and the like. The weighting factors Wa, Wb, and Wc are set to have a relationship of Wa> Wb> 0 and Wc <0. That is, in determining the coefficient K, the coefficient K increases as the ratio Ar of the A region where the combustion temperature is low increases, and the coefficient K decreases as the ratio Cr of the C region where the combustion temperature is high increases. A coefficient K is set in a state in which the ascent measure is implemented.

  After the coefficient K is set in step S16, it is determined in step S17 whether or not the coefficient K exceeds a predetermined value 1 (predetermined value for starting combustion temperature rise). In step S17, the coefficient K is determined to be a predetermined value. If it is determined that it does not exceed 1 (No), it is determined that the ratio Cr of the C region where the combustion temperature is high and the ratio Br of the intermediate B region are large, that is, it is determined that the accumulation amount of the combustion chamber deposit is small. In step S18, the counters Ca, Cb, and Cc are cleared, and the process returns without implementing measures for increasing the combustion temperature.

  If it is determined in step S17 that the coefficient K exceeds the predetermined value 1 (Yes), it is determined that the ratio Ar of the A region where the combustion temperature is low is large, that is, it is determined that the accumulation amount of the combustion chamber deposit is large, In step S19, a measure for increasing the combustion temperature is implemented to increase the combustion temperature. In step S20, the combustion temperature rise flag is turned ON, and the process proceeds to step S18. When it is determined that the ratio Ar of the A region where the combustion temperature is low is large, that is, when it is determined that there are many operating conditions in which the combustion deposit tends to increase, the combustion temperature is increased so that the combustion chamber deposit decreases. I have to. Thereafter, the process proceeds to step S18, where the counters Ca, Cb, Cc are cleared, and a measure for increasing the combustion temperature is implemented and the process returns.

  As a measure for increasing the combustion temperature, it is possible to lower the EGR rate by operating the EGR valve 23 (see FIG. 1) to the closed side to reduce the exhaust gas recirculation amount. As shown in FIG. 5, when the EGR rate is lowered, the combustion temperature increases. Therefore, the combustion temperature can be raised by reducing the EGR rate.

  As a measure for increasing the combustion temperature, the ignition timing by the spark plug 3 (see FIG. 1) is advanced, the maximum pressure is increased, and the position of the maximum pressure is brought close to top dead center. As shown in FIG. 6, since the combustion temperature increases when the ignition timing is advanced, the combustion temperature can be increased by advancing the ignition timing.

  Further, as a measure for increasing the combustion temperature, it is conceivable to suppress the cooling water cooling and raise the cooling water temperature of the engine 1 (see FIG. 1). As shown in FIG. 7, when the cooling water temperature is raised, the combustion temperature becomes higher. Therefore, the combustion temperature can be raised by raising the cooling water temperature.

  The measures for increasing the combustion temperature can be performed by appropriately combining a decrease in the EGR rate, an advance of the ignition timing, and an increase in the coolant temperature.

  Returning to the flowchart of FIG. 3, when the combustion temperature increase measure is returned in the implementation state, first, at step S11, whether or not the vehicle has traveled the predetermined distance 2 in the combustion temperature increase process state, the predetermined distance 1 is set at step S12. It is determined whether or not the vehicle has traveled. Here, since the predetermined distance 1 <the predetermined distance 2 is set, the process returns to the predetermined distance 1 in step S12. Thereafter, when the predetermined distance 1 is reached, the process proceeds to step S13, where the values of the counters Ca, Cb, Cc are added to obtain the count value integration T. After obtaining the count value integration T in step S13, the ratio of each region is obtained in step S14. Since the measure for raising the combustion temperature has already been implemented in step S15, it is determined that the combustion temperature rise flag is ON (Yes), and the coefficient K for raising the combustion temperature is changed in step S21. In step S21, the coefficient K is obtained by multiplying the ratio Cr of the C region where the combustion temperature is high by the weighting coefficient Wc (Wc <0), and the coefficient K is changed to only the coefficient K of the C region.

  After changing the coefficient K in step S21, it is determined in step S22 whether or not the coefficient K is equal to or less than a predetermined value 2 (predetermined value for stopping the rise in combustion temperature). In step S22, the coefficient K is set to the predetermined value 2. If it is determined as follows (Yes), the process proceeds to step S23 and the combustion temperature increase measure is stopped. That is, when the operation state of the C region where the combustion temperature is high is determined, the combustion temperature increase measure is stopped. If it is determined in step S22 that the coefficient K is not less than or equal to the predetermined value 2 (exceeded: No), a return is made (R), and the return is continued in step S12 until the vehicle travels the predetermined distance 1 again.

  If it is determined in step S11 that the vehicle has traveled the predetermined distance 2 in the combustion temperature increase process, the process proceeds to step S23 and the combustion temperature increase measure is stopped. That is, the predetermined distance 1 (<predetermined distance 2) is repeated several times, but if the predetermined distance 2 continues in the state of the combustion temperature increasing process even if the ratio of the C region does not reach the predetermined value 2, the combustion temperature increasing measure Appropriate control can be implemented by canceling.

  In step S24, the combustion temperature rise flag is turned OFF, and the process proceeds to step S18 to clear the counters Ca, Cb, Cc and return.

  As described above, the ratio of the A region where the combustion temperature is low on the low load / low rotation side, the C region where the combustion temperature is high on the high load / high rotation side, and the intermediate B region are obtained, and the ratio of the A region where the combustion temperature is low Measures to raise the combustion temperature when there are many are taken into consideration, so consider the increase in the amount of residual solid components deposited by operation in the low temperature combustion region and the decrease in the amount of residual solid components deposited by operation in the high temperature combustion region. Thus, it is possible to suppress the measure for excessively raising the combustion temperature simply by increasing the operation in the low temperature combustion region.

  Therefore, even when the engine 1 that can increase the EGR rate and improve the fuel efficiency with the intake flow control valve closed is operated under a low combustion temperature condition, the combustion chamber deposit of the combustion chamber 6 Therefore, it is possible to achieve both suppression of combustion chamber deposit and improvement of fuel consumption.

  INDUSTRIAL APPLICABILITY The present invention is used in the industrial field of a combustion control device for an internal combustion engine that reduces the accumulation of soot remaining in a combustion chamber or a residual solid component that is a solid component of oil when operated at a low combustion temperature. can do.

1 is a schematic configuration diagram of a combustion control device for an internal combustion engine according to an embodiment of the present invention. It is a control flowchart for setting an operation area. It is a control flowchart of combustion temperature. It is a map for setting an operation area. It is a graph showing the relationship between combustion temperature and an EGR rate. It is a graph showing the relationship between combustion temperature and ignition timing. It is a graph showing the relationship between combustion temperature and cooling water temperature.

Explanation of symbols

1 Engine body (Engine)
2 Cylinder Head 3 Spark Plug 4 Ignition Coil 5 Intake Port 6 Combustion Chamber 7 Intake Valve 9 Intake Manifold 10 Fuel Injection Valve (Injection)
DESCRIPTION OF SYMBOLS 11 Exhaust port 12 Exhaust valve 13 Exhaust manifold 14 Intake pipe 15 Throttle valve 16 Throttle position sensor 17 Air flow sensor 18 Surge tank 20 Exhaust pipe 21 Exhaust gas circulation port (EGR port)
22 EGR pipe 23 EGR valve 25 Flow control valve (intake flow control valve)
26 Actuator 31 ECU (Electronic Control Unit)
32 Crank angle sensor 33 Water temperature sensor

Claims (4)

Combustion temperature detection means for detecting or estimating which one of a plurality of combustion regions including a low temperature combustion region where the combustion temperature is low and a high temperature combustion region where the combustion temperature is high is an operating region per unit period of the combustion chamber of the internal combustion engine When,
A temperature raising measure means for raising the combustion temperature of the combustion chamber of the internal combustion engine;
Combustion control means for operating the temperature raising measure means,
The combustion control means integrates the outputs of the combustion temperature detection means to obtain a ratio of the plurality of combustion areas, and increases based on the obtained ratio when the ratio of the low temperature combustion area increases, and the high temperature combustion A combustion control apparatus for an internal combustion engine, wherein a coefficient that decreases when the ratio of the region increases is calculated, and the temperature raising measure means is operated when the coefficient exceeds a predetermined value . The combustion control means stops the temperature increase measure means when it is determined that the coefficient is equal to or less than another predetermined value for stopping the increase in combustion temperature after the temperature increase measure means is actuated. The combustion control device for an internal combustion engine according to claim 1. The combustion temperature detecting means may you detecting or estimating which of the internal combustion engine of the engine rotational speed average value and the plurality of regions based on the average value of the load per during unit period The combustion control device for an internal combustion engine according to claim 1 or 2. The temperature raising measure means is at least one of means for reducing the amount of exhaust gas recirculated by the exhaust gas recirculation means, means for advancing ignition timing, and means for increasing the coolant temperature of the internal combustion engine. The combustion control device for an internal combustion engine according to any one of claims 1 to 3.

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