JP2012225172A - Oil supply system of internal combustion engine - Google Patents

Abstract

An oil supply system for an internal combustion engine capable of suppressing a decrease in durability performance of an exhaust emission control device due to occurrence of a misfire phenomenon is provided.
The system includes an oil supply passage that supplies oil fed by an oil pump to each part of the internal combustion engine, and an oil that is communicated with the oil supply passage and injects the oil in the passage toward the piston of the internal combustion engine. An oil jet and an exhaust gas purification device that is provided in an exhaust passage of the internal combustion engine and purifies exhaust gas. Through the operation control of the pressure change device, when the misfire phenomenon occurs in the internal combustion engine (S101: YES), the pressure of the oil in the oil supply passage is increased compared to when the misfire phenomenon does not occur (S101: NO). Set (S103).
[Selection] Figure 3

Description

  The present invention relates to an oil supply system for an internal combustion engine that supplies oil to various parts of the engine.

  Usually, an internal combustion engine is provided with an oil pan in which oil is stored and an oil pump that is driven when the engine is operated to pump oil in the oil pan. The oil pumped by the oil pump is supplied to each part of the internal combustion engine through an oil supply passage formed in the internal combustion engine for the purpose of lubrication and the like.

  The internal combustion engine is provided with an oil jet for blowing oil to the piston in the vicinity of the piston. The oil jet has a nozzle communicated with the oil supply passage, and the oil in the oil supply passage is ejected from the nozzle toward the piston. The piston is cooled by the oil injected from the oil jet.

  Here, when the internal combustion engine is operated, a phenomenon in which fuel does not sufficiently burn in the combustion chamber, a so-called misfire phenomenon may occur. Patent Document 1 proposes a device for reducing the oil pressure in the oil supply passage when a misfire phenomenon occurs in order to suppress the occurrence of such a misfire phenomenon. Normally, the oil jet has a structure in which the amount of oil ejected from the nozzle is reduced when the oil pressure in the oil supply passage becomes low. Therefore, in the apparatus described in Patent Document 1, since the amount of oil injected from the oil jet is reduced when a misfire phenomenon occurs, the temperature in the combustion chamber can be increased as the piston cooling effect decreases due to this. Thus, the occurrence of misfire is suppressed.

JP 2009-156186 A

  By the way, as a matter of course, even if the temperature of the combustion chamber is increased by suppressing the cooling of the piston by the oil jet as in the apparatus described in Patent Document 1, the occurrence of the misfire phenomenon may not be suppressed.

  When the misfire phenomenon occurs, the unburned fuel component (HC) is discharged into the exhaust passage of the internal combustion engine, so that the component burns (oxidizes) in the exhaust passage, and the temperature in the exhaust passage becomes higher. May be high. Since the exhaust passage is provided with an exhaust purification device with a built-in catalyst or filter for purifying the exhaust gas, if the temperature in the exhaust passage rises due to the occurrence of a misfire phenomenon, the temperature of the exhaust purification device May become unnecessarily high, leading to a decrease in durability of the apparatus.

  And in the situation where generation | occurrence | production of a misfire phenomenon cannot be suppressed as mentioned above, when the oil pressure in an oil supply passage is reduced so that the temperature in a combustion chamber may be raised like the apparatus of patent document 1, it accompanies this. As a result, the temperature of the gas discharged from the combustion chamber to the exhaust passage becomes high, and on the contrary, the durability performance of the exhaust purification device tends to be lowered.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an oil supply system for an internal combustion engine that can suppress a decrease in durability performance of the exhaust emission control device due to the occurrence of a misfire phenomenon. is there.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
According to a first aspect of the present invention, there is provided an oil supply passage that supplies oil pumped by an oil pump to each part of the internal combustion engine, and the oil in the passage is injected toward the piston of the internal combustion engine in communication with the oil supply passage. An oil jet that is disposed in the exhaust passage of the internal combustion engine, and a pressure changing device that changes the pressure of the oil in the oil supply passage. When the misfire phenomenon occurs in the internal combustion engine, the pressure changing device sets the oil pressure in the oil supply passage to a higher pressure than when no misfire phenomenon occurs.

  For this reason, when a misfire phenomenon occurs, the amount of oil injected from the oil jet per unit time can be increased, and the piston cooling effect can be enhanced to keep the temperature in the combustion chamber low. Thereby, since the temperature of the gas discharged from the combustion chamber to the exhaust passage is lowered, the temperature of the exhaust gas in the exhaust passage can be kept low, and an unnecessary increase in the temperature of the exhaust purification device can be restrained. Therefore, it is possible to suppress a decrease in the durability performance of the exhaust emission control device due to the occurrence of a misfire phenomenon.

  When the exhaust temperature in the exhaust passage of the internal combustion engine is low, the temperature of the exhaust purification device is unlikely to become unnecessarily high, which may lead to a decrease in the durability performance of the exhaust purification device due to the occurrence of a misfire phenomenon Is also low. In this regard, in the configuration according to claim 2, the pressure of the oil in the oil supply passage is increased by the pressure change device on the condition that the temperature of the exhaust gas in the exhaust passage is higher than a predetermined temperature when the misfire phenomenon occurs. Set to

  In such a configuration, even when a misfire phenomenon occurs, the oil pressure in the oil supply passage is low when the exhaust temperature in the exhaust passage is low, that is, when it is unlikely to cause a decrease in the durability of the exhaust purification device. Is set to low pressure. At this time, since the amount of oil injected from the oil jet is reduced and the temperature in the combustion chamber is increased, the instability of the combustion state of the fuel in the combustion chamber can be suppressed and the occurrence of a misfire phenomenon can be suppressed. In addition, since the oil pressure in the oil supply passage can be kept low, the operating load of the oil pump can be kept small, and this can suppress a reduction in fuel consumption performance of the internal combustion engine.

  In addition, when the exhaust gas temperature in the exhaust passage is high at the time of occurrence of a misfire phenomenon, that is, when there is a relatively high possibility that the exhaust performance of the exhaust purification device will be lowered, the oil pressure in the oil supply passage is set to a high pressure. be able to. At this time, since the amount of oil injected from the oil jet increases and the temperature in the combustion chamber decreases, an unnecessary increase in the temperature of the exhaust purification device can be suppressed, and a decrease in durability can be suppressed.

As described above, according to the above configuration, it is possible to suppress the deterioration of the durability performance of the exhaust emission control device due to the occurrence of the misfire phenomenon and to suppress the occurrence of the misfire phenomenon.
In the configuration of the third aspect, the oil pressure control for adjusting the oil pressure in the oil supply passage according to the operating state of the internal combustion engine is executed by the pressure changing device. In addition, by limiting the use of the low pressure side of the oil pressure adjustment range in oil pressure control when a misfire phenomenon occurs, the oil pressure in the oil supply passage is compared to when no misfire phenomenon occurs. Set to high pressure.

  According to such a configuration, when the misfire phenomenon occurs, the cooling effect of the piston due to the oil jet can be suppressed and the cooling effect can be maintained in a large state, so that the gas discharged from the combustion chamber to the exhaust passage The temperature of can be kept low.

  According to the fourth aspect, the oil pressure control can be executed such that the operating state of the pressure changing device is selectively switched to one of the first operating mode and the second operating mode. In addition, by prohibiting switching to the first operation mode in such a pressure change device, it is possible to limit the use of the low pressure side region in the oil pressure adjustment range in the oil pressure control.

  Note that, as a pressure changing device capable of realizing the execution of the oil pressure control such as switching to one of the first operation mode and the second operation mode, according to claim 5, the oil pressure in the oil supply passage is controlled. A relief valve that opens as it rises and discharges part of the oil in the passage to the outside of the passage, and the pressure at which the relief valve opens is set to a low pressure when the first operation mode is selected, while When the two operation modes are selected, one having a switching valve set to a high pressure can be employed.

1 is a schematic diagram showing a schematic configuration of an oil supply system for an internal combustion engine according to an embodiment embodying the present invention. 1 is a schematic diagram showing a relationship between an operating state of a pressure change device and an engine operation region. The flowchart which shows the specific execution procedure of an oil pressure control process.

Hereinafter, an oil supply system for an internal combustion engine according to an embodiment of the present invention will be described.
As shown in FIG. 1, an intake passage 13 is connected to the combustion chamber 12 of the internal combustion engine 11, and a fuel injection valve 14 is attached to the intake passage 13. Air is sucked into the combustion chamber 12 of the internal combustion engine 11 through the intake passage 13 and fuel injected from the fuel injection valve 14 is supplied. When the air-fuel mixture composed of the intake air and the injected fuel is ignited by the spark plug 15, the air-fuel mixture burns, the piston 16 reciprocates, and the crankshaft 17 of the internal combustion engine 11 rotates. . The air-fuel mixture after combustion is sent out from the combustion chamber 12 of the internal combustion engine 11 to the exhaust passage 18 as exhaust. The exhaust passage 18 is provided with an exhaust purification device 19 incorporating a three-way catalyst. The exhaust gas sent to the exhaust passage 18 is purified when passing through the exhaust purification device 19 and then exhausted to the outside of the exhaust passage 18.

  The apparatus according to the present embodiment includes an electronic control unit 30 that executes various controls for the operation of the internal combustion engine 11. The electronic control unit 30 includes a central processing unit (CPU) that executes various arithmetic processes related to various controls, a non-volatile memory (ROM) that stores programs and data necessary for the arithmetic operation, and the arithmetic results of the CPU. A volatile memory (RAM) that is temporarily stored, an input / output port for inputting / outputting signals to / from the outside, and the like are provided.

  Various sensors are connected to the input port of the electronic control unit 30. Examples of such sensors include an accelerator sensor 31 for detecting an operation amount (accelerator operation amount AC) of an accelerator operation member (not shown), and an opening degree of the throttle valve 20 provided in the intake passage 13 (throttle opening TA). ) Is provided. In addition, an air amount sensor 33 for detecting the amount of air passing through the intake passage 13 (passage air amount GA), a rotation sensor 34 for detecting the rotational speed of the crankshaft 17 (engine rotational speed NE), and exhaust. A temperature sensor 35 and the like for detecting the temperature of the exhaust gas in the passage 18 (exhaust temperature THE) are also provided. The temperature sensor 35 is attached to a portion of the exhaust passage 18 upstream of the exhaust purification device 19 in the exhaust flow direction (in this embodiment, an exhaust manifold).

  The electronic control unit 30 grasps the operating state of the internal combustion engine 11 such as the engine rotational speed NE and the engine load KL based on the output signals of various sensors. The engine load KL is calculated based on the intake air amount of the internal combustion engine 11 and the engine rotational speed NE obtained based on the accelerator operation amount AC, the throttle opening degree TA, and the passage air amount GA. The electronic control unit 30 outputs a command signal to various drive circuits connected to the output port in accordance with the operation state of the internal combustion engine 11 thus grasped. In this way, the electronic control unit 30 controls the operation of the fuel injection valve 14 (fuel injection control), the operation control of the spark plug 15 (ignition timing control), the operation control of the throttle valve 20 (throttle control), and the pressure described later. Various controls such as operation control (oil pressure control) of the changing device 40 are executed.

Hereinafter, a structure for supplying oil to each part of the internal combustion engine 11 will be described.
The internal combustion engine 11 is provided with an oil pan 21 for storing oil and an oil pump 22 for pumping oil in the oil pan 21. As the oil pump 22, an engine drive type drive-coupled to the crankshaft 17 is employed. When the internal combustion engine 11 is operated and the crankshaft 17 rotates, the oil pump 22 is driven by this rotation. As a result, the oil stored in the oil pan 21 is pumped up through the oil passage 23 and supplied to each part of the internal combustion engine 11 (for example, a lubrication site such as a bearing portion of the crankshaft 17 or a hydraulic operating device). The pressure is fed through the passage 24. An oil jet 25 communicates with the oil supply passage 24. When the internal combustion engine 11 is operated, oil in the oil supply passage 24 is injected from the oil jet 25 toward the piston 16.

  The internal combustion engine 11 is provided with a pressure changing device 40 for adjusting the pressure of oil in the oil supply passage 24 (hereinafter referred to as oil pressure PO). The pressure changing device 40 includes a relief oil passage 41 that is connected to the pumping oil passage 23 and the oil supply passage 24 and extends so as to bypass the oil pump 22. A relief valve 42 that opens as the oil pressure PO in the oil supply passage 24 increases is provided in the middle of the relief oil passage 41. When the relief valve 42 is opened, a part of the oil in the oil supply passage 24 is pumped up and discharged to the oil passage 23 through the relief oil passage 41. At this time, the oil in the oil supply passage 24 is discharged. The pressure PO will decrease.

  The pressure changing device 40 includes a changing mechanism 43 for changing the set pressure of the relief valve 42 (specifically, the oil pressure at which the relief valve 42 opens). Hereinafter, the changing mechanism 43 will be described.

  A sleeve 44 is provided inside the relief valve 42 so as to be reciprocally movable, and an end 44A on one side (downward in FIG. 1) in the moving direction of the sleeve 44 and an inner wall surface of the relief valve 42 Thus, the switching chamber 45 is partitioned. When oil is supplied to the switching chamber 45, the end 44A of the sleeve 44 is pressed by the pressure of the oil, and the sleeve 44 moves in the direction in which the switching chamber 45 is expanded (upper side in FIG. 1). Will come to do. On the other hand, when oil is discharged from the switching chamber 45, the sleeve 44 moves in a direction (downward in FIG. 1) in which the switching chamber 45 is reduced.

  A valve internal oil passage 46 extending along the moving direction is formed inside the sleeve 44. A piston 47 is provided inside the valve internal oil passage 46 so as to be capable of reciprocating in the same direction as the sleeve 44. The piston 47 is constantly urged to one side (upper side in FIG. 1) in the moving direction by a spring 48.

  A through hole 42 </ b> A that communicates the inside and the outside is formed in the wall portion of the relief valve 42 so as to open at an intermediate portion in the moving direction of the piston 47. The sleeve 44 is formed with a through hole 44 </ b> B that communicates the inside and the outside so as to open at an intermediate portion in the moving direction of the piston 47.

  In the relief valve 42, oil is introduced into the valve internal oil passage 46 from the relief oil passage 41 (specifically, the portion upstream of the relief valve 42 [upstream oil passage 41 </ b> A]), and the introduced oil This pressure acts against the urging force of the spring 48 so as to press the piston 47 (downward in FIG. 1).

  In such a relief valve 42, when the engine speed NE is low and the oil pumping amount of the oil pump 22 is small, the pressure of oil introduced into the valve internal oil passage 46 through the oil supply passage 24 and the upstream oil passage 41A is low. In addition, the amount of movement of the piston 47 is small. Therefore, the moving position of the piston 47 is a position above the through hole 44B of the sleeve 44, that is, the upstream oil passage 41A and the relief oil passage 41 downstream from the relief valve 42 (downstream oil passage 41B). Therefore, the relief valve 42 is not opened at this time.

  On the other hand, when the engine speed NE increases and the oil pumping amount of the oil pump 22 increases, the pressure of oil introduced into the valve internal oil passage 46 via the oil supply passage 24 and the upstream oil passage 41A increases. In addition, the amount of movement of the piston 47 increases. As a result, the movement position of the piston 47 is a position below the through hole 44B of the sleeve 44, that is, a position allowing the communication between the upstream oil passage 41A and the downstream oil passage 41B of the relief oil passage 41 (for example, in the figure). Therefore, the relief valve 42 is opened at this time.

  When the relief valve 42 is opened, the oil flows in the order of the upstream oil passage 41A, the valve internal oil passage 46, the through hole 44B of the sleeve 44, the through hole 42A of the outer wall of the relief valve 42, and the downstream oil passage 41B. As a result, the oil in the oil supply passage 24 is pumped up and discharged to the oil passage 23.

  As described above, in the present embodiment, the relief valve 42 opens as the oil pressure PO in the oil supply passage 24 increases, and a part of the oil in the oil supply passage 24 is removed from the oil pan 21 (in detail, It functions such as returning to the pumping oil passage 23).

  In the relief valve 42, when the moving position of the sleeve 44 changes, the position of the through hole 44B of the sleeve 44 changes accordingly. Therefore, the moving position of the piston 47 at which communication between the upstream oil passage 41A and the downstream oil passage 41B of the relief oil passage 41 is allowed to change, and the set pressure of the relief valve 42 changes. It becomes like this.

  In the present embodiment, as described above, the moving position of the sleeve 44 can be changed by switching between the state in which oil is supplied to the switching chamber 45 and the state in which oil is discharged from the switching chamber 45. It has become. Therefore, the set pressure of the relief valve 42 can be changed through the change of the moving position of the sleeve 44.

  The change mechanism 43 includes a switching valve 49 for switching between a state where oil is supplied into the switching chamber 45 and a state where oil is discharged from the switching chamber 45. The switching valve 49 includes a first switching oil passage 50 connected to the upstream oil passage 41A, a second switching oil passage 51 connected to the switching chamber 45, and a third connection connected to the downstream oil passage 41B. A switching oil passage 52 is connected to each other. The switching valve 49 changes the communication state between the ports provided corresponding to the switching oil passages 50 to 52, so that the lubricating oil is supplied from the switching chamber 45 to the state where the oil is supplied to the switching chamber 45. Switch to the discharged state.

  Specifically, through the operation control of the switching valve 49, the first switching oil passage 50 and the second switching oil passage 51 communicate with each other, and the first switching oil passage 50 and the third switching oil passage 52 communicate with each other. In the blocked state (first communication state), the oil in the oil supply passage 24 is supplied to the switching chamber 45 via the upstream oil passage 41A, the first switching oil passage 50, and the second switching oil passage 51. Become so.

  On the other hand, through the operation control of the switching valve 49, the communication between the first switching oil passage 50 and the second switching oil passage 51 and the communication between the first switching oil passage 50 and the third switching oil passage 52 are both blocked. When the second switching oil passage 51 and the third switching oil passage 52 are communicated with each other (second communication state), the oil in the switching chamber 45 is transferred to the second switching oil passage 51, the third switching oil passage 52, and the downstream side. The oil is drawn up to the oil passage 23 through the oil passage 41B.

  Note that even if the operation mode of the switching valve 49 (specifically, the moving position of the sleeve 44) is the same, the oil pressure PO in the oil supply passage 24 when the relief valve 42 is opened passes through the relief oil passage 41. Therefore, it varies depending on the amount of oil pumped up from the oil supply passage 24 and discharged to the oil passage 23, and therefore does not become constant. Specifically, the oil pressure PO in the oil supply passage 24 increases as the engine speed NE increases.

Such operation control (oil pressure control) of the pressure changing device 40 is basically executed based on the following idea.
When the oil pressure PO in the oil supply passage 24 is increased, the operating load of the oil pump 22 increases accordingly, and the fuel efficiency performance of the internal combustion engine 11 decreases. Therefore, in order to improve fuel efficiency, it is desirable to set the set pressure of the relief valve 42 to a low pressure. Further, in the engine operation region where the engine speed NE is high (high rotation region) and the engine operation region where the engine load KL is large (high load region), the amount of oil required for lubricating each part of the engine increases. Therefore, in a high rotation region or a high load region, it is preferable to set the oil pressure PO in the oil supply passage 24 to a high pressure in order to ensure lubrication performance.

  In the present embodiment based on such circumstances, the set pressure of the relief valve 42 is set to a low pressure in the engine operation region (low rotation / low load region) where the engine speed NE is low and the engine load KL is small. At this time, the operation control of the switching valve 49 is executed so that the oil is supplied into the switching chamber 45 (the first communication state), and the operating state of the pressure changing device 40 is the oil in the oil supply passage 24. Since it becomes the 1st operation mode which adjusts pressure PO to low pressure, improvement in fuel consumption performance is aimed at.

  On the other hand, in the engine operation region where the engine speed NE is high (high rotation region) and the engine operation region where the engine load KL is large (high load region), the set pressure of the relief valve 42 is set to a high pressure. At this time, since the operating state of the pressure changing device 40 becomes the second operating mode in which the oil pressure PO in the oil supply passage 24 is adjusted to a high pressure, the lubricating performance is ensured.

FIG. 2 shows the relationship between the set pressure of the relief valve 42 (specifically, the operating state of the pressure changing device 40) and the operating region of the internal combustion engine 11.
As shown in FIG. 2, the engine operation region determined by the engine speed NE and the engine load KL is divided into two regions, a low pressure region R1 and a high pressure region R2, by a boundary line L. As the low pressure region R1, an operation region in which the engine rotational speed NE is lower than the boundary line L and the engine load KL is smaller is set. In the low pressure region R1, the operation of the pressure changing device 40 is controlled to be in the first operation mode. On the other hand, as the high pressure region R2, an operation region where the engine speed NE is higher than the boundary line L or an operation region where the engine load KL is larger is set. In the high pressure region R2, the operation of the pressure changing device 40 is controlled to be in the second operation mode.

  As described above, in the present embodiment, the oil pressure control is performed such that the operating state of the pressure changing device 40 is selectively switched to one of the first operating mode and the second operating mode. Further, in the present embodiment, the switching valve 49 sets the set pressure of the relief valve 42 to a low pressure when the first operating mode is selected, while increasing the set pressure of the relief valve 42 when selecting the second operating mode. It works like setting.

  In the present embodiment, the electronic control unit 30 executes a determination process for determining whether or not a phenomenon in which fuel is not sufficiently burned in the combustion chamber 12 of the internal combustion engine 11, that is, a so-called misfire phenomenon has occurred. The result of the determination by the misfire determination is referred to when the oil pressure control is executed. Hereinafter, this misfire determination will be described.

  In this misfire determination, first, in the combustion stroke of the internal combustion engine 11, a time T [i] required for the crankshaft 17 to rotate by 30 degrees at the crank angle starting from the compression top dead center is detected. Further, the difference (= T [i] −T [i−1]) between the time T [i] and the time T [i−1] detected in the previous combustion cycle is calculated as the rotation fluctuation amount ΔT. The Then, when this rotational fluctuation amount ΔT exceeds a predetermined threshold value, it is determined that a misfire phenomenon has occurred.

  When no misfire phenomenon has occurred, a value in the vicinity of “0” is calculated as the rotation fluctuation amount ΔT. On the other hand, when a misfire phenomenon occurs, a relatively large value is detected as the rotation fluctuation amount ΔT. As described above, since the rotation fluctuation amount ΔT when the misfire phenomenon occurs and the rotation fluctuation amount ΔT when the misfire phenomenon does not occur are different from each other, the rotation fluctuation amount associated with the occurrence of the misfire phenomenon depends on the threshold value. It is possible to determine an increase in ΔT.

  By the way, when a misfire phenomenon occurs in the internal combustion engine 11, the unburned fuel component (HC) is discharged from the combustion chamber 12 to the exhaust passage 18, so that the component is combusted (oxidized) in the exhaust passage 18. As a result, the exhaust temperature in the exhaust passage 18 may increase. If the exhaust temperature in the exhaust passage 18 becomes high in this way, the temperature of the exhaust purification device 19 provided in the exhaust passage 18 also becomes unnecessarily high. This causes a change in the characteristics of the three-way catalyst, and so on. There is a possibility that the durability performance of the device 19 is lowered.

  Here, the oil jet 25 has a structure in which the amount of oil injected from the nozzle decreases as the oil pressure PO in the oil supply passage 24 decreases. Therefore, by increasing the oil pressure PO in the oil supply passage 24 and increasing the amount of oil injected from the oil jet 25, the cooling effect of the piston 16 increases and the temperature of the piston 16 decreases. As a result, a portion of the heat generated in the combustion chamber 12 is transferred to the piston 16, so that the temperature in the combustion chamber 12 can be kept low and discharged from the combustion chamber 12 to the exhaust passage 18. The gas temperature can be kept low. Therefore, when a misfire phenomenon occurs in the internal combustion engine 11, the temperature of the gas (exhaust gas) discharged from the combustion chamber 12 to the exhaust passage 18 is kept low by increasing the oil pressure PO in the oil supply passage 24. It will be possible.

  In view of this point, in the present embodiment, when the misfire phenomenon occurs in the internal combustion engine 11, the oil pressure in the oil supply passage 24 is set to be higher than when the misfire phenomenon does not occur. Yes. Specifically, when the misfire phenomenon occurs, the operating state of the pressure changing device 40 is switched to the second operating mode and switching to the first operating mode is prohibited.

  As a result, when a misfire phenomenon occurs in the internal combustion engine 11, it is possible to keep the amount of oil from being increased while suppressing the amount of oil injected from the oil jet 25 per unit time from decreasing. Therefore, the amount of oil injected from the oil jet 25 per unit time can be increased, and the cooling effect of the piston 16 can be increased by that much, and the temperature in the combustion chamber 12 can be suppressed low. At this time, since the temperature of the gas discharged from the combustion chamber 12 of the internal combustion engine 11 to the exhaust passage 18 is lowered, the temperature of the exhaust gas in the exhaust passage 18 is kept low to suppress an unnecessary increase in the temperature of the exhaust purification device 19. Can do. Therefore, it is possible to suppress a decrease in the durability performance of the exhaust purification device 19 due to the occurrence of a misfire phenomenon.

  Even if a misfire phenomenon occurs in the internal combustion engine 11, when the exhaust temperature THE in the exhaust passage 18 is low, the temperature of the exhaust purification device 19 is unlikely to become unnecessarily high. The possibility of deteriorating the durability performance of the exhaust purification device 19 is also low.

  In view of this point, in the present embodiment, when the misfire phenomenon occurs in the internal combustion engine 11, the operation state of the pressure change device 40 is changed on condition that the exhaust temperature THE in the exhaust passage 18 is higher than the predetermined temperature TL. Switching to the second operation mode and prohibition of switching to the first operation mode are executed.

  Therefore, even when a misfire phenomenon occurs in the internal combustion engine 11, when the exhaust temperature THE in the exhaust passage 18 is low, that is, when there is a low possibility that the exhaust performance of the exhaust purification device 19 will be reduced, the internal combustion engine The operation control of the pressure changing device 40 is executed in accordance with the operating state of the engine 11. In this case, when the operating state of the internal combustion engine 11 is in the low rotation and low load region (see FIG. 2), the operating state of the pressure changing device 40 is in the first operating mode in which the oil pressure PO in the oil supply passage 24 is adjusted to a low pressure. Since the switching is performed, it is possible to suppress a decrease in fuel consumption performance of the internal combustion engine 11 correspondingly. In addition, since the oil injection amount per unit time from the oil jet 25 is reduced at this time and the cooling effect of the piston 16 is reduced, the temperature in the combustion chamber 12 can be increased. It is also possible to suppress the occurrence of misfire by suppressing instability of the combustion state of the fuel.

  On the other hand, when the misfire phenomenon occurs in the internal combustion engine 11 and the exhaust temperature THE in the exhaust passage 18 is high, that is, when there is a relatively high possibility that the exhaust performance of the exhaust purification device 19 will be lowered, the pressure change device The operation state of 40 is switched to the second operation mode and switching to the first operation mode is prohibited. At this time, since the amount of oil injected from the oil jet 25 increases and the temperature in the combustion chamber 12 increases, a decrease in the durability of the exhaust purification device 19 can be suppressed.

  As described above, according to the present embodiment, it is possible to suppress the deterioration of the durability performance of the exhaust emission control device 19 due to the occurrence of the misfire phenomenon in the internal combustion engine 11 and to suppress the occurrence of the misfire phenomenon itself.

  FIG. 3 shows a specific execution procedure of the process related to oil pressure control (oil pressure control process) including the process when the misfire phenomenon described above occurs. The series of processes shown in the flowchart of FIG. 5 is executed by the electronic control unit 30 as an interrupt process at predetermined intervals.

  As shown in FIG. 3, in this process, it is first determined whether or not the misfire phenomenon has occurred in the internal combustion engine 11 based on the determination result of the misfire determination described above (step S101). Here, it is determined that the misfire phenomenon has occurred when the elapsed time after the last determination that the misfire phenomenon has occurred in the determination process is less than the predetermined time. That is, in the present embodiment, when the internal combustion engine 11 is generated at a predetermined period after it is determined that the misfire phenomenon has occurred in the misfire determination, or when the frequency at which it is determined that the misfire phenomenon has occurred in the misfire determination is high. It is judged that there is.

  When it is determined that a misfire phenomenon has occurred (step S101: YES), it is determined whether the exhaust temperature THE in the exhaust passage 18 is higher than the predetermined temperature TL (step S102). The predetermined temperature TL is a temperature at which it is possible to achieve both suppression of a decrease in durability performance of the exhaust purification device 19 due to occurrence of a misfire phenomenon and suppression of occurrence of the misfire phenomenon itself through the processing of step S102. Or obtained in advance based on the result of the simulation and stored in the electronic control unit 30.

  When the exhaust temperature THE in the exhaust passage 18 is higher than the predetermined temperature TL (step S102: YES), the set pressure of the relief valve 42 is set to a high pressure (step S103). At this time, the operation control of the switching valve 49 is executed so that the oil is discharged from the switching chamber 45 (FIG. 1) (the second communication state), and the operating state of the pressure changing device 40 is the oil supply passage. This is the second operation mode in which the oil pressure PO in 24 is adjusted to a high pressure.

  As described above, in the present embodiment, when the misfire phenomenon occurs in the internal combustion engine 11, when the exhaust temperature THE in the exhaust passage 18 is high, the oil pressure control is performed so that the oil pressure PO in the oil supply passage 24 becomes high. Executed.

  On the other hand, when the exhaust temperature THE in the exhaust passage 18 is equal to or lower than the predetermined temperature TL (step S102: NO in FIG. 3), it depends on the operating range of the internal combustion engine 11 determined by the engine speed NE and the engine load KL. The set pressure of the relief valve 42 is switched.

  Specifically, in the engine operation region (low rotation / low load region) where the engine speed NE is low and the engine load KL is small (step S104: YES), the set pressure of the relief valve 42 is set to a low pressure (step S104). S105). That is, at this time, the operation control of the switching valve 49 is executed so that the oil is supplied into the switching chamber 45 (FIG. 1) (the first communication state), and the operating state of the pressure changing device 40 is the oil This is the first operation mode in which the oil pressure PO in the supply passage 24 is adjusted to a low pressure.

  In the engine operation region where the engine speed NE is high (high rotation region) and the engine operation region where the engine load KL is large (high load region) (step S104 in FIG. 3: NO), the set pressure of the relief valve 42 is set to a high pressure. (Step S103). That is, at this time, the operating state of the pressure changing device 40 becomes the second operating mode.

  When it is determined that the misfire phenomenon does not occur in the internal combustion engine 11 (step S101: NO), the relief valve is set according to the operating range of the internal combustion engine 11 determined by the engine speed NE and the engine load KL. The set pressure of 42 is switched (steps S103 to S105).

As described above, according to the present embodiment, the effects described below can be obtained.
(1) When the misfire phenomenon occurs, the oil pressure PO in the oil supply passage 24 is set to be higher than when the misfire phenomenon does not occur. Therefore, it is possible to suppress a decrease in the durability performance of the exhaust purification device 19 due to the occurrence of a misfire phenomenon.

  (2) When the misfire phenomenon occurs, on the condition that the exhaust temperature THE in the exhaust passage 18 is higher than the predetermined temperature TL, the switching of the operating state of the pressure changing device 40 to the second operating mode and the first operating mode are performed. The prohibition of switching is executed. Therefore, it is possible to suppress the deterioration of the durability performance of the exhaust purification device 19 due to the occurrence of the misfire phenomenon and to suppress the occurrence of the misfire phenomenon itself.

  (3) When the misfire phenomenon occurs, the operating state of the pressure changing device 40 is switched to the second operating mode, and switching to the first operating mode is prohibited. As a result, when the misfire phenomenon occurs, the cooling effect of the piston 16 due to the oil injection from the oil jet 25 can be suppressed and the cooling effect can be kept large. It is possible to keep the temperature of the gas discharged to low.

The embodiment described above may be modified as follows.
The execution mode of the determination process for determining whether or not a misfire phenomenon has occurred in the internal combustion engine 11 can be arbitrarily changed. Further, the presence or absence of the misfire phenomenon is not limited to determination based on the fluctuation mode of the engine rotational speed NE, but based on parameters other than the engine rotational speed NE, such as determination based on the pressure in the combustion chamber 12 of the internal combustion engine 11. It is also possible to determine.

A temperature sensor for detecting the exhaust temperature in the exhaust passage 18 may be provided downstream of the exhaust purification device 19 in the exhaust passage 18 in the exhaust flow direction.
In the process of step S102 in the oil pressure control process (see FIG. 3), instead of determining whether or not the exhaust temperature THE in the exhaust passage 18 is higher than the predetermined temperature TL, the temperature of the exhaust purification device 19 is predetermined. You may make it judge whether it is higher than temperature. In short, it is only necessary to be able to determine that when the misfire phenomenon occurs, the temperature of the exhaust purification device 19 may be increased to such an extent that the durability performance of the exhaust purification device 19 is lowered. As the temperature of the exhaust purification device 19, a value detected by a dedicated temperature sensor is used, or a value estimated based on the operating state of the internal combustion engine 11 (engine rotational speed NE, passage air amount GA, etc.) is used. be able to.

  -The process of step S102 in the oil pressure control process may be omitted. That is, when the misfire phenomenon occurs in the internal combustion engine 11, the operating state of the pressure changing device 40 may be set to the second operating mode without depending on the exhaust temperature THE in the exhaust passage 18.

  The operation state of the pressure change device 40 is set to the second operation mode when the misfire phenomenon occurs in the internal combustion engine 11, while the operation state of the pressure change device 40 is set to the first operation mode when the misfire phenomenon does not occur. In addition, the oil pressure control may be executed.

  In addition to the case where it is determined that the misfire phenomenon has occurred, and when there is a history that is determined that the misfire phenomenon has occurred, the operation state of the pressure change device 40 is changed to the second operation state. The switching to the first operating mode in the same operating state may be prohibited.

Not only the pressure changing device 40 including the relief valve 42 and the switching valve 49, but the oil pressure PO in the oil supply passage 24 can be selectively switched between a low pressure state and a relatively high pressure state. If possible, a pressure changing device having an arbitrary configuration can be employed. Examples of such a pressure changing device include the following [Example 1] and [Example 2].
[Example 1] The movement position of the sleeve 44 of the relief valve 42 is changed by power other than oil pressure, such as by using an electromagnetically driven actuator.
[Example 2] Oil is supplied to an oil circuit including a first check valve having a low valve opening pressure, a second check valve having a high valve opening pressure, and a switching valve for switching between a state in which the first check valve functions and a state in which the first check valve does not function. Provided to be connected to the passage 24 and the pumping oil passage 23 together, and adjusts the oil pressure PO in the oil supply passage 24 through the operation control of the switching valve.

  As the oil pump, a variable discharge capacity type may be adopted, and the oil pressure PO in the oil supply passage 24 may be changed by changing the discharge amount itself of the oil pump. Examples of such oil pumps include an electric oil pump that can adjust the discharge amount through the operation control of the electric motor that is the drive source, and a swash plate type oil pump that can adjust the oil discharge amount by changing the angle of the swash plate. Can be mentioned.

  -When the misfire phenomenon occurs, the switching of the operating state of the pressure change device 40 to the first operating mode is not prohibited, and switching to the first operating mode may be limited. For example, instead of prohibiting the switching of the operating state of the pressure changing device 40 to the first operating mode in all periods during which it is determined that a misfire phenomenon has occurred, it is prohibited only in a part of the same period. , And can be prohibited repeatedly intermittently during the same period.

  -Instead of the pressure change device 40 whose operation state can be switched in two stages of the first operation mode and the second operation mode, a pressure change device whose operation state can be switched in three or more stages may be provided. . It is also possible to provide a pressure changing device that changes the operating state steplessly so as to change the oil pressure PO in the oil supply passage 24 steplessly within a predetermined pressure range. In short, any device capable of changing the oil pressure PO in the oil supply passage 24 can be employed as a pressure changing device.

  -When the misfire phenomenon occurs, not only prohibiting (or limiting) the switching of the operating state of the pressure changing device 40 to the first operating mode, but also on the low pressure side of the adjustment range of the oil pressure PO in the oil pressure control. The use of the area may be prohibited or restricted. Even with such a configuration, when the misfire phenomenon occurs, the oil pressure PO in the oil supply passage 24 can be set higher than when the misfire phenomenon does not occur. As such a configuration, for example, in a pressure change device in which the operating state is switched in multiple stages, a configuration is adopted in which switching to an operating state where the oil pressure PO is lower than the intermediate operating state is prohibited (or limited). can do. Further, in the pressure changing device in which the operating state is changed steplessly, a configuration is adopted in which the change to the operating state where the oil pressure PO is lower than the predetermined operating state is prohibited (or limited). It is also possible.

  DESCRIPTION OF SYMBOLS 11 ... Internal combustion engine, 12 ... Combustion chamber, 13 ... Intake passage, 14 ... Fuel injection valve, 15 ... Spark plug, 16 ... Piston, 17 ... Crankshaft, 18 ... Exhaust passage, 19 ... Exhaust purification device, 20 ... Throttle valve 21 ... oil pan, 22 ... oil pump, 23 ... pumping oil passage, 24 ... oil supply passage, 25 ... oil jet, 30 ... electronic control unit, 31 ... accelerator sensor, 32 ... throttle sensor, 33 ... air amount sensor, 34 ... Rotation sensor, 35 ... Temperature sensor, 40 ... Pressure changing device, 41 ... Relief oil passage, 41A ... Upstream oil passage, 41B ... Downstream oil passage, 42 ... Relief valve, 42A ... Through hole, 43 ... Change mechanism 44 ... Sleeve, 44A ... End, 44B ... Through-hole, 45 ... Switching chamber, 46 ... Valve internal oil passage, 47 ... Piston, 48 ... Spring, 49 ... Switching valve, 0 ... first switching oil passage, 51 ... second switching oil passage, 52 ... third switching oil passage.

Claims (5)

An oil supply passage for supplying oil pumped by an oil pump to each part of the internal combustion engine;
An oil jet that communicates with the oil supply passage and injects oil in the passage toward the piston of the internal combustion engine;
An exhaust purification device that is provided in an exhaust passage of the internal combustion engine and purifies exhaust;
An oil supply system for an internal combustion engine, comprising: a pressure changing device that sets the pressure of oil in the oil supply passage to a higher level when a misfire phenomenon occurs in the internal combustion engine than when no misfire phenomenon occurs. The oil supply system for an internal combustion engine according to claim 1,
The oil supply system for an internal combustion engine, wherein the pressure changing device sets the oil pressure to a high pressure on condition that the temperature of the exhaust gas in the exhaust passage is higher than a predetermined temperature. The oil supply system for an internal combustion engine according to claim 1 or 2,
The pressure changing device performs oil pressure control for adjusting the pressure of oil in the oil supply passage according to an operating state of the internal combustion engine, and is included in an oil pressure adjustment range in the oil pressure control. The oil supply system for an internal combustion engine is characterized in that the pressure of the oil is set to a high pressure when the misfire phenomenon occurs by restricting the use of the low pressure side region. The oil supply system for an internal combustion engine according to claim 3,
In the oil pressure control, either one of a first operation mode in which the operation state of the pressure changing device is adjusted to a low pressure in the oil supply passage and a second operation mode in which the pressure of the oil is adjusted to a high pressure. Control to selectively switch to
An oil supply system for an internal combustion engine, wherein the pressure change device restricts use of the low pressure side region by prohibiting switching to the first operation mode. The oil supply system for an internal combustion engine according to claim 4,
The pressure changing device includes a relief valve that opens as the oil pressure in the oil supply passage increases and discharges a part of the oil in the passage to the outside of the passage, and a pressure at which the relief valve opens. An oil supply system for an internal combustion engine, comprising: a switching valve that sets a low pressure when the first operating mode is selected, and sets a high pressure when the second operating mode is selected.

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