JP2013057273A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of an internal combustion engine capable of suitably restraining oil leakage into an intake passage from a supercharger.SOLUTION: A compressor impeller and a throttle valve of the supercharger are arranged in order from the upstream side in the intake passage of the internal combustion engine. An oil supply device for supplying oil in a housing of the supercharger is installed in the internal combustion engine. A rotary shaft of the compressor impeller is rotatably supported in the housing, and a seal member for sealing the oil leakage to the intake passage via a clearance is arranged in the clearance between the rotary shaft and an inner surface of the housing. When throttle downstream pressure PA1 is lower than first determining pressure J1 and throttle upstream pressure PA2 is lower than second determining pressure J2 (S11: YES, and S12: YES), the pressure of the oil supplied in the housing of the supercharger is reduced by the oil supply device (S14) as compared with the case that the pressure is not so lowered (S11: NO, or S12: NO).

Description

  The present invention relates to a control device for an internal combustion engine equipped with a supercharger.

  In order to increase the intake air amount of an internal combustion engine, it is often used to mount a supercharger. As a supercharger, there is known a turbocharger provided with a compressor impeller provided rotatably in an intake passage of an internal combustion engine. In such a turbocharger, a bearing portion is formed in the housing, and the rotation shaft of the compressor impeller is rotatably supported by the bearing portion. Oil used for lubrication between the rotating shaft of the compressor impeller and the bearing portion is supplied into the housing. Further, a seal member for suppressing oil leakage from the inside of the housing to the intake passage through the gap is attached to the gap between the inner surface of the housing and the rotation shaft of the compressor impeller.

  The pressure in the intake passage of the internal combustion engine changes according to the operating state of the internal combustion engine, the operating state of the supercharger, and the like. Further, when a throttle valve is provided in the intake passage of the internal combustion engine, the pressure in the intake passage temporarily becomes very low when the opening of the throttle valve is reduced during the deceleration operation of the internal combustion engine. There is. At this time, the difference between the pressure in the intake passage and the pressure in the housing of the supercharger becomes large, so that the oil in the housing may be sucked into the intake passage and leak due to the pressure difference. Such oil leakage is not preferable because it causes an increase in oil consumption.

  Therefore, conventionally, as in the device described in Patent Document 1, when the pressure on the intake passage side of the seal member, specifically, the pressure on the back surface of the compressor impeller communicating with the same portion (impeller back pressure) is low, It has been proposed to introduce atmospheric pressure to the rear part. According to such an apparatus, since the impeller back pressure is increased by introducing a relatively high atmospheric pressure and the pressure difference is suppressed to be small, oil leakage at the portion where the seal member is disposed is suppressed.

JP-A-6-33896

  By the way, in the apparatus described in Patent Document 1, when the atmospheric pressure is introduced into the portion on the intake passage side of the seal member in order to suppress the difference between the impeller back pressure and the housing internal pressure, the introduction of the atmospheric pressure is started. It is inevitable that a time delay occurs until the impeller back pressure actually increases. For this reason, even if the introduction of atmospheric pressure is started on the condition that the impeller back pressure has actually decreased, it is difficult to properly suppress the pressure difference, and the intake air from the turbocharger housing caused by the pressure difference It can also be said that it is difficult to properly suppress oil leakage into the passage.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a control device for an internal combustion engine that can suitably suppress oil leakage from a supercharger into an intake passage.

Hereinafter, means for achieving the above-described object and its operation and effects will be described.
The apparatus described in each claim includes a compressor impeller of a supercharger disposed in an intake passage, a throttle valve disposed downstream of the compressor impeller in the intake passage in the intake air flow direction, and a turbocharger housing The present invention is applied to an internal combustion engine having an oil supply device for supplying oil therein. In the turbocharger, a rotation shaft of the compressor impeller is rotatably supported in the housing, and a seal member that seals oil leakage to the intake passage through the gap between the rotation shaft and the inner surface of the housing is provided. Arranged.

  In such a device, when the throttle valve opening (throttle opening) is rapidly reduced during engine speed reduction or the like, the pressure in the intake passage downstream of the throttle valve in the intake passage direction (throttle downstream pressure) is temporarily It becomes low. If the throttle opening rapidly increases in this state, a low-pressure throttle downstream pressure is introduced into a portion upstream of the throttle valve in the intake flow direction, and at this time, the pressure around the compressor impeller in the intake passage decreases. As a result, there is a large difference between the pressure on the back surface of the compressor impeller (impeller back pressure), more specifically, the pressure on the intake passage side of the seal member communicating with the back surface and the pressure in the housing of the turbocharger. Therefore, the oil in the housing may be sucked into the intake passage and leak due to this pressure difference.

  In the above device, if the throttle downstream pressure becomes extremely low and the throttle upstream pressure (pressure between the compressor impeller and the throttle valve in the intake passage) becomes somewhat low, the impeller back pressure is likely to be excessively lowered. Become. Specifically, if the throttle opening rapidly increases in such a state, the introduction of the throttle downstream pressure to the upstream side of the throttle valve may reduce the throttle upstream pressure and the impeller back pressure may become excessively low.

  In this regard, according to the device according to claim 1 or 3, the impeller back pressure is excessively decreased immediately after the throttle downstream pressure is lower than the first determination pressure and the throttle upstream pressure is lower than the second determination pressure. It can be determined that there is a high possibility of inviting. Based on this determination, it is determined appropriately that oil leakage from the supercharger into the intake passage may be caused at this time, and that the sealing performance by the sealing member may be lowered. Can do. Accordingly, it is possible to prepare for this by predicting that there is a possibility of oil leakage from the supercharger into the intake passage. Therefore, it is possible to execute the process for suppressing oil leakage from the turbocharger to the intake passage at an appropriate timing according to the period during which oil leakage may actually occur. It can suppress suitably.

  Specifically, in the device according to claim 1, when the throttle downstream pressure is lower than the first determination pressure and the throttle upstream pressure is lower than the second determination pressure, the case is not the case (that is, the throttle downstream pressure is the first determination pressure). The pressure of the oil supplied into the housing by the oil supply device is set to a low pressure as compared with the case where the pressure is 1 determination pressure or higher, or the throttle upstream pressure is higher than the second determination pressure.

  Thereby, since the amount of oil supplied into the housing per unit time can be reduced, even if the difference between the impeller back pressure and the internal pressure of the housing of the supercharger becomes large at this time, Due to the pressure difference, the amount of oil that leaks from the housing into the intake passage can be reduced. Moreover, when the engine rotational speed is switched from the deceleration state to the acceleration state, the time during which the impeller back pressure is excessively low is short. At this time, since the rotational speed of the compressor impeller is low, the oil necessary for lubrication of the rotating shaft is reduced. The amount is small. Therefore, even if the amount of oil supplied into the housing by the oil supply device at this time is reduced, there is little possibility of causing unnecessary deterioration in the lubrication performance of the rotating shaft of the compressor impeller. Therefore, according to the above apparatus, oil leakage from the inside of the turbocharger housing into the intake passage can be suitably suppressed.

  According to the third aspect of the present invention, when the throttle downstream pressure is lower than the first determination pressure and the throttle upstream pressure is lower than the second determination pressure, the opening speed of the throttle valve is higher than that when the throttle determination is not. Set to low speed. Here, when the throttle upstream pressure is reduced by increasing the throttle opening while the throttle downstream pressure is very low, the degree of decrease in the throttle upstream pressure increases as the increase rate of the throttle opening increases. Therefore, according to the third aspect of the present invention, since the throttle valve opening speed is set to a low speed, the degree of decrease in the throttle upstream pressure, and hence the impeller back pressure, can be kept small. Oil leakage from the housing to the intake passage due to the difference between the pressure and the internal pressure of the turbocharger housing can be suitably suppressed.

  In addition, the structure which reduces the valve opening speed of a throttle valve is realizable by setting the upper limit of the valve opening speed of a throttle valve like Claim 4.

  As described above, when the throttle opening is rapidly increased immediately after the throttle downstream pressure is lower than the first determination pressure and the throttle upstream pressure is lower than the second determination pressure, the impeller back pressure is excessively decreased. It is possible to appropriately determine that there is a possibility of incurring.

  According to the apparatus of claim 2, in addition to the throttle downstream pressure being lower than the first determination pressure and the throttle upstream pressure being lower than the second determination pressure, the throttle valve opening speed is higher than the determination speed. That is, it can be determined that there is a possibility that the sealing performance by the sealing member may be lowered when the throttle opening actually increases rapidly. Therefore, it is possible to accurately determine that there is a high possibility that the impeller back pressure will be excessively decreased immediately after that, and based on that determination, it is accurately determined that the sealing performance by the sealing member may be reduced. can do.

  In the apparatus according to claim 2, when the throttle downstream pressure is lower than the first determination pressure, the throttle upstream pressure is lower than the second determination pressure, and the valve opening speed of the throttle valve is higher than the determination speed, so (Ie, when the throttle downstream pressure is equal to or higher than the first determination pressure, when the throttle upstream pressure is equal to or higher than the second determination pressure, or when the throttle valve opening speed is equal to or lower than the determination speed). Thus, the pressure of the oil supplied into the housing by the oil supply device is set to a low pressure. As a result, the amount of oil supplied into the housing per unit time can be reduced, so that the intake passage from the housing is caused by the difference between the impeller back pressure at this time and the internal pressure of the turbocharger housing. The amount of oil leaking into the tank can be reduced. Therefore, according to the above apparatus, oil leakage from the inside of the turbocharger housing into the intake passage can be suitably suppressed.

1 is a schematic diagram showing a schematic configuration of an internal combustion engine to which a first embodiment embodying the present invention is applied. Sectional drawing which shows the cross-section of the compressor of a supercharger, and its peripheral part. The flowchart which shows the execution procedure of the leak suppression process concerning 1st Embodiment. The timing chart which shows an example of the execution aspect of the leak suppression process. The flowchart which shows the execution procedure of the leak suppression process concerning 2nd Embodiment. The timing chart which shows an example of the execution aspect of the leak suppression process. The flowchart which shows the execution procedure of the leak suppression process concerning 3rd Embodiment. The timing chart which shows an example of the execution aspect of the leak suppression process.

(First embodiment)
A control apparatus for an internal combustion engine according to a first embodiment embodying the present invention will be described below.

  As shown in FIG. 1, a throttle mechanism 12 for changing the cross-sectional area of the intake passage 11 is attached to the intake passage 11 of the internal combustion engine 10. The throttle mechanism 12 includes a throttle valve 13 disposed in the intake passage 11 and a throttle motor 14 connected to the throttle valve 13. In the apparatus of the present embodiment, the opening degree of the throttle valve 13 (throttle opening degree TA) is adjusted in accordance with the engine operating state through the operation control (throttle control) of the throttle motor 14 based on the operating state of the internal combustion engine 10. The

  The apparatus of the present embodiment includes an oil supply apparatus 20 for supplying oil to each part of the apparatus. The oil supply device 20 includes an oil pan 21 that is attached to the internal combustion engine 10 and stores oil, and an engine-driven oil pump 22 that is drivingly connected to the output shaft of the internal combustion engine 10. When the internal combustion engine 10 is operated, the oil pump 22 is activated and the oil in the oil pan 21 is pumped to each part of the apparatus through the oil supply passage 23. The oil supply device 20 includes a relief passage 24 and a relief valve 25 for relieving the oil in the oil supply passage 23 and returning it to the oil pan 21. As the relief valve 25, an electromagnetically driven valve capable of changing the pressure (relief pressure) at which oil in the oil supply passage 23 is relieved is adopted.

  The internal combustion engine 10 includes a compressor 31 disposed in an intake flow direction upstream side (hereinafter simply referred to as an upstream side) of a throttle mechanism 12 in the intake passage 11 and a turbine 32 disposed in an exhaust passage 15. A so-called exhaust-driven supercharger 30 is attached.

  The apparatus of the present embodiment is provided with an electronic control unit 40 that executes various controls related to the operation of the internal combustion engine 10. The electronic control unit 40 captures output signals of various sensors and executes various arithmetic processes based on the output signals. Based on the calculation results, the electronic control unit 40 controls the throttle mechanism 12 and the relief valve 25. Various controls are executed.

  As various sensors, for example, a throttle sensor 41 for detecting the opening degree of the throttle valve 13 (throttle opening degree TA) or the downstream side in the intake flow direction (hereinafter, simply downstream) of the throttle valve 13 in the intake passage 11 of the internal combustion engine 10. Side) pressure sensor (throttle downstream pressure PA1) is provided. Further, in order to detect the pressure (throttle upstream pressure PA2) of the portion upstream of the throttle valve 13 in the intake passage 11 of the internal combustion engine 10 (specifically, the portion between the compressor impeller 31A and the throttle valve 13 in the intake passage 11). The pressure sensor 43 is also provided.

  In the supercharger 30, the compressor 31 and the turbine 32 are integrally formed via a connecting portion 33. A compressor impeller 31A is disposed inside the compressor 31 (specifically, a part constituting a part of the intake passage 11), and inside the turbine 32 (specifically, a part constituting a part of the exhaust passage 15). A turbine wheel 32A is disposed on the side. Both the compressor impeller 31 </ b> A and the turbine wheel 32 </ b> A are integrally formed with the rotary shaft 34.

  As shown in FIG. 2, a radial bearing 36 and a thrust bearing 37 are formed inside the housing 35 of the supercharger 30. The rotating shaft 34 of the supercharger 30 is rotatably supported by the radial bearing 36 and the thrust bearing 37.

  In the supercharger 30, lubricating oil is supplied to the radial bearing 36 and the thrust bearing 37 through the oil supply passage 23 (see FIG. 1) by the oil supply device 20. The inside of the housing 35 of the supercharger 30 is communicated with the crankcase of the internal combustion engine 10 via a drain passage 26 (FIG. 1), and the oil after being used for lubrication through the drain passage 26 is inside the crankcase, As a result, it is returned to the oil pan 21.

  A seal member 38 is attached to a gap between the rotary shaft 34 and the inner surface 35A (FIG. 2) of the housing 35 in the supercharger 30. The seal member 38 allows the inside of the intake passage 11 to pass from the inside of the housing 35 through the gap (specifically, the portion indicated by “AR1” in FIG. 2 where the radial bearing 36 and the thrust bearing 37 are formed). (In detail, the oil leakage to “AR2” in FIG. 2) is sealed.

  In the apparatus of this embodiment, oil leakage from the housing 35 to the intake passage 11 due to the difference between the pressure in the intake passage 11 of the internal combustion engine 10 and the pressure in the housing 35 of the supercharger 30 is suppressed. Processing (leakage suppression processing) is executed as follows.

  FIG. 3 shows the execution procedure of the leakage suppression process. The series of processes shown in the flowchart of FIG. 8 is executed by the electronic control unit 40 as an interrupt process at predetermined intervals.

As shown in FIG. 3, in this process, it is first determined whether or not all of the following [first condition] to [third condition] are satisfied (steps S11 to S13).
[First Condition] The throttle downstream pressure PA1 is lower than the first determination pressure J1 (step S11).
[Second Condition] The throttle upstream pressure PA2 is lower than the second determination pressure J2 (step S12).
[Third Condition] The increase speed of the throttle opening TA is higher than the determination speed JV (step S13).

  When all of the [first condition] to [third condition] are satisfied (all of steps S11 to S13 are “YES”), it is determined that the sealing performance by the seal member 38 may be reduced. . That is, at this time, there is a high possibility that oil leaks from the housing 35 to the intake passage 11 due to the difference between the pressure in the intake passage 11 of the internal combustion engine 10 and the pressure in the housing 35 of the supercharger 30. To be judged. In the present embodiment, the first determination pressure J1, the second determination pressure J2, and the determination speed JV are constant values that can accurately determine that the sealing performance by the seal member 38 may be deteriorated. Is obtained in advance based on the results of various experiments and simulations and stored in the electronic control unit 40.

  On the other hand, when one of the [first condition] to [third condition] is not satisfied (any of steps S11 to S13 is “NO”), the sealing performance by the seal member 38 may be lowered. The judgment is not made. That is, at this time, it is determined that the possibility of oil leakage from the housing 35 to the intake passage 11 due to the pressure difference is very low.

  Here, when the throttle opening degree TA is rapidly reduced at the time of engine speed reduction or the like, the throttle downstream pressure PA1 is temporarily reduced. If the throttle opening TA rapidly increases in this state, the low-pressure throttle downstream pressure PA1 is introduced into the portion upstream of the throttle valve 13, and at this time, the pressure around the compressor impeller 31A in the intake passage 11 decreases. To do. As a result, the pressure (impeller back pressure) at the back surface portion of the compressor impeller 31A (portion indicated by “AR2” in FIG. 2), more specifically, the pressure at the portion on the intake passage 11 side of the seal member 38 communicating with the back surface portion. And the pressure in the housing 35 of the supercharger 30 (portion indicated by “AR1” in FIG. 2) increases. Therefore, the oil in the housing 35 may be sucked into the intake passage 11 and leak due to this pressure difference.

  In such a device, if the throttle downstream pressure PA1 becomes extremely low and the throttle upstream pressure PA2 becomes low to some extent, there is a high possibility that the impeller back pressure will be excessively lowered. Specifically, if the throttle opening TA rapidly increases in such a state, the introduction of the throttle downstream pressure PA1 to the upstream side of the throttle valve 13 may cause the throttle upstream pressure PA2 to decrease and the impeller back pressure to become excessively low.

  Therefore, according to the apparatus of the present embodiment, it is determined that the throttle downstream pressure PA1 is lower than the first determination pressure J1 [first condition], and it is determined that the throttle upstream pressure PA2 is lower than the second determination pressure J2. If both of the two conditions are satisfied, it is possible to appropriately determine that there is a high possibility that the impeller back pressure will be excessively reduced immediately after that.

  Note that when the throttle upstream pressure PA2 is sufficiently high, even if the low throttle downstream pressure PA1 flows upstream from the throttle valve 13, there is a possibility that the throttle upstream pressure PA2 and the impeller back pressure will be excessively decreased. Is low. If only the [first condition] of the [first condition] and [second condition] is set, it may be erroneously determined that there is a high possibility that the impeller back pressure will be excessively reduced. Also, when the throttle downstream pressure PA1 is not so low, the degree of decrease in the throttle upstream pressure PA2 when the throttle downstream pressure PA1 flows upstream from the throttle valve 13 is small. It is unlikely to cause an excessive decrease in pressure. If only [Second Condition] of [First Condition] and [Second Condition] is set, in such a case, there is a possibility that it is erroneously determined that there is a high possibility of causing an excessive decrease in the impeller back pressure. In this regard, according to the present embodiment, when both the [first condition] and the [second condition] are satisfied, it is appropriately determined that there is a high possibility that the impeller back pressure will be excessively reduced immediately afterward. Can do.

  Moreover, in addition to satisfying both [first condition] and [second condition], [third condition] for determining that the valve opening speed of the throttle valve 13 is higher than the determination speed JV is satisfied. That is, it can be accurately determined that there is a high possibility that the impeller back pressure will be excessively decreased due to the fact that the throttle opening TA has actually increased rapidly.

  Based on this determination, there is a possibility of oil leakage from the housing 35 of the supercharger 30 to the intake passage 11 of the internal combustion engine 10 at this time, and the sealing performance by the sealing member 38 is lowered. It is possible to appropriately determine that there is a possibility. As a result, it is possible to prepare for this by predicting that there is a possibility of causing oil leakage from the supercharger 30 into the intake passage 11, and therefore processing for suppressing oil leakage is actually performed. It is possible to execute it at an appropriate timing in accordance with a period during which oil leakage may occur, and oil leakage can be suitably suppressed through the same processing.

  Specifically, when all the [first condition] to [third condition] are satisfied (“YES” in all of step S11 to step S13), the sealing performance by the sealing member 38 may be reduced. Is determined, and a process for suppressing oil leakage from the inside of the housing 35 to the intake passage 11 is executed (step S14). In this process, specifically, the operation of the relief valve 25 is controlled so that the relief pressure becomes a predetermined pressure PL set in advance. In the present embodiment, based on the results of various experiments and simulations, the pressure is lower than the lower limit of the setting range of the oil pressure when relief from the relief valve 25 is not performed, and the intake passage 11 extends from the housing 35. An oil pressure is required in advance to obtain a minimum lubrication performance in the radial bearing 36 and the thrust bearing 37 while suppressing oil leakage to a small amount. The same pressure is stored in the electronic control unit 40 as the predetermined pressure PL.

  As described above, in the apparatus according to the present embodiment, when all of the [first condition] to [third condition] are satisfied, the case is not true (that is, any one of [first condition] to [third condition]). Compared to the case where only one is not satisfied, the pressure of the oil supplied into the housing 35 (specifically, the radial bearing 36 and the thrust bearing 37) of the supercharger 30 via the oil supply passage 23 becomes lower.

  On the other hand, if any one of [First Condition] to [Third Condition] is not satisfied (any of Steps S11 to S13 is “NO”), the oil from the inside of the housing 35 to the intake passage 11 will be described. Processing for suppressing leakage is not executed. Specifically, the relief pressure is set to a high pressure through the operation control of the relief valve 25 so that relief by the relief valve 25 is not performed in the low pressure region (step S15). In this case, basically, an amount of oil corresponding to the engine rotational speed is supplied to each part of the internal combustion engine 10 and the supercharger 30 via the oil supply passage 23.

Hereinafter, the effect | action by performing a leakage suppression process is demonstrated, referring FIG.
FIG. 4 is a timing chart showing an example of an execution mode of the leakage suppression process.
In the example shown in FIG. 4, at time t11, when the throttle opening degree TA becomes smaller when the engine rotational speed is reduced, the throttle downstream pressure PA1 thereafter decreases. Further, the throttle upstream pressure PA2 and the impeller back pressure also decrease as the engine rotation speed and the rotation speed of the rotation shaft 34 of the compressor impeller 31A decrease. Incidentally, at this time, the throttle downstream pressure PA1 is extremely lower than the throttle upstream pressure PA2. When the throttle downstream pressure PA1 decreases and falls below the first determination pressure J1, the [first condition] is satisfied (time t12), and further when the throttle upstream pressure PA2 decreases and falls below the second determination pressure J2. Second condition] is satisfied (time t13).

  In such a state, when the throttle opening TA rapidly increases to accelerate the engine speed at time t14, the low-pressure throttle downstream pressure PA1 flows into the upstream side of the throttle valve 13, so that the throttle upstream pressure PA2, As a result, the impeller back pressure suddenly drops. In this example, since the [third condition] is satisfied by increasing the throttle opening degree TA at time t14, all of the [first condition] to [third condition] are satisfied and the sealing performance by the seal member 38 is improved. It is determined that there is a possibility of reduction.

  Then, over a period in which all of the [first condition] to [third condition] are satisfied (time t14 to t15), the relief pressure is set to a predetermined pressure PL in order to suppress oil leakage from the inside of the housing 35 to the intake passage 11. Thus, the operation of the relief valve 25 is controlled. As a result, the pressure of the oil supplied into the housing 35 of the supercharger 30 decreases.

  As described above, in the apparatus according to the present embodiment, when it is determined that the sealing performance by the sealing member 38 may be lowered (indicated by a solid line in the drawing), compared with the case where it is not (one point in the drawing). The pressure of the oil supplied into the housing 35 of the supercharger 30 through the oil supply passage 23 is reduced. As a result, the amount of oil supplied per unit time to the portion of the housing 35 adjacent to the seal member 38 can be reduced, and this is the case when the difference between the impeller back pressure and the internal pressure of the housing 35 becomes large. However, the amount of oil that leaks from the housing 35 to the intake passage 11 due to the pressure difference can be reduced.

  In addition, the time during which the impeller back pressure is excessively low when switching the engine rotational speed from the deceleration state to the acceleration state is short, and at this time, the rotational speed of the compressor impeller 31A is low, which is necessary for lubricating the rotary shaft 34. The amount of oil is low. Therefore, even if the amount of oil supplied into the housing 35 by the oil supply device 20 is reduced at this time, there is a low possibility that the lubricating performance of the rotating shaft 34 of the compressor impeller 31A will be unnecessarily reduced.

Therefore, according to the present embodiment, oil leakage from the housing 35 of the supercharger 30 into the intake passage 11 can be suitably suppressed.
Then, when any of the [first condition] to [third condition] is not satisfied due to the subsequent increase in the throttle downstream pressure PA1, the increase in the throttle upstream pressure PA2, or the decrease in the increase speed of the throttle opening TA (time) t15) The execution of the process for suppressing oil leakage from the inside of the housing 35 to the intake passage 11 is stopped. Specifically, the relief pressure is set to a high pressure through the operation control of the relief valve 25 so that relief by the relief valve 25 is not performed in the low pressure region. Thus, thereafter, an amount of oil corresponding to the engine rotational speed is supplied to each part of the internal combustion engine 10 and the supercharger 30 via the oil supply passage 23.

As described above, according to the present embodiment, the following effects can be obtained.
(1) When the throttle downstream pressure PA1 is lower than the first determination pressure J1, the throttle upstream pressure PA2 is lower than the second determination pressure J2, and the opening speed of the throttle valve 13 is higher than the determination speed JV, or not As compared with the above, the pressure of the oil supplied into the housing 35 of the supercharger 30 through the oil supply passage 23 is lowered. Therefore, oil leakage from the housing 35 of the supercharger 30 into the intake passage 11 can be suitably suppressed.

(Second Embodiment)
Hereinafter, the control apparatus for an internal combustion engine according to the second embodiment that embodies the present invention will be described focusing on differences from the first embodiment.

  In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. This embodiment is different from the first embodiment in the execution procedure of the leakage suppression process. Hereinafter, the leakage suppression process according to the present embodiment will be specifically described.

  FIG. 5 shows an execution procedure of the leakage suppression process according to the present embodiment. Note that a series of processes shown in the flowchart of FIG. 8 is executed by the electronic control unit 40 as an interrupt process at predetermined intervals.

As shown in FIG. 5, in this process, first, it is determined whether or not both the [first condition] and [second condition] are satisfied (step S11, step S12).
When both [first condition] and [second condition] are satisfied (step S11: YES and step S12: YES), it is determined that the sealing performance by the seal member 38 may be reduced. That is, at this time, there is a high possibility that oil leaks from the housing 35 to the intake passage 11 due to the difference between the pressure in the intake passage 11 of the internal combustion engine 10 and the pressure in the housing 35 of the supercharger 30. To be judged.

  According to the apparatus of the present embodiment, it is determined that the throttle downstream pressure PA1 is lower than the first determination pressure J1 [first condition], and it is determined that the throttle upstream pressure PA2 is lower than the second determination pressure J2. It is possible to properly determine that there is a high possibility that the impeller back pressure will be excessively reduced immediately after the condition] is satisfied. As a result, it is possible to prepare for this by predicting that there is a possibility of causing oil leakage from the supercharger 30 into the intake passage 11, and therefore processing for suppressing oil leakage is actually performed. It is possible to execute it at an appropriate timing in accordance with a period during which oil leakage may occur, and oil leakage can be suitably suppressed through the same processing.

  Specifically, when both [first condition] and [second condition] are satisfied (step S11: YES and step S12: YES), it is determined that the sealing performance by the sealing member 38 may be reduced. Then, the operation of the relief valve 25 is controlled so that the relief pressure becomes a predetermined pressure PL determined in advance (step S14).

  On the other hand, if either [first condition] or [second condition] is not satisfied (step S11: NO or step S12: NO), the sealing performance by the sealing member 38 may be reduced. Judgment is not made. At this time, the relief pressure is set to a high pressure through the operation control of the relief valve 25 so that relief by the relief valve 25 is not performed in the low pressure region (step S15).

Hereinafter, the effect | action by performing a leakage suppression process is demonstrated, referring FIG.
FIG. 6 is a timing chart showing an example of an execution mode of the leakage suppression process.
In the example shown in FIG. 6, at time t21, when the throttle opening degree TA becomes smaller when the engine speed is reduced, the throttle downstream pressure PA1 thereafter decreases. Further, the throttle upstream pressure PA2 and the impeller back pressure also decrease as the engine rotation speed and the rotation speed of the rotation shaft 34 of the compressor impeller 31A decrease.

  In this example, as the throttle downstream pressure PA1 and the throttle upstream pressure PA2 decrease, the [first condition] and the [second condition] are satisfied at time t22, and the sealing performance by the seal member 38 may decrease. It is determined that there is. Then, over a period in which both the [first condition] and the [second condition] are satisfied (time t22 to t24), the relief pressure is predetermined in order to suppress oil leakage from the inside of the housing 35 to the intake passage 11. The operation of the relief valve 25 is controlled so as to reach a predetermined pressure PL. As a result, the pressure of the oil supplied into the housing 35 of the supercharger 30 decreases.

  As described above, in the apparatus according to the present embodiment, when it is determined that the sealing performance by the sealing member 38 may be lowered (indicated by a solid line in the drawing), compared with the case where it is not (one point in the drawing). The pressure of the oil supplied into the housing 35 of the supercharger 30 through the oil supply passage 23 is reduced. Thus, in preparation for the difference between the impeller back pressure and the internal pressure of the housing 35 immediately after that, the oil supply amount per unit time for the portion adjacent to the seal member 38 in the housing 35 of the supercharger 30 is set in advance. Can be kept to a small amount.

  In this example, at the subsequent time t23, the throttle opening TA rapidly increases to accelerate the engine speed, and the throttle upstream pressure PA2 and the impeller back pressure decrease, and the impeller back pressure and the internal pressure of the housing 35 are reduced. The difference increases. However, since the amount of oil supplied per unit time to the portion adjacent to the seal member 38 in the housing 35 of the supercharger 30 is previously suppressed to a small amount, The amount of oil that leaks into the intake passage 11 is suppressed to a low level.

  Then, when the [first condition] and [second condition] are not satisfied due to the subsequent increase in the throttle downstream pressure PA1 or the increase in the throttle upstream pressure PA2 (time t24), the inside of the housing 35 leads to the intake passage 11 Execution of processing for suppressing oil leakage is stopped.

As described above, according to the present embodiment, the effect described in the following (2) can be obtained.
(2) When the throttle downstream pressure PA1 is lower than the first determination pressure J1 and the throttle upstream pressure PA2 is lower than the second determination pressure J2, the turbocharger is connected via the oil supply passage 23 as compared to the case where it is not. The pressure of the oil supplied into the 30 housings 35 is lowered. Therefore, oil leakage from the housing 35 of the supercharger 30 into the intake passage 11 can be suitably suppressed.

(Third embodiment)
Hereinafter, a control device for an internal combustion engine according to a third embodiment embodying the present invention will be described focusing on differences from the first embodiment and the second embodiment.

  In the following description, the same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The execution procedure of the leakage suppression process is different between the first embodiment and the second embodiment and this embodiment. Hereinafter, the leakage suppression process according to the present embodiment will be specifically described.

  FIG. 7 shows the execution procedure of the leakage suppression process according to this embodiment. Note that a series of processes shown in the flowchart of FIG. 8 is executed by the electronic control unit 40 as an interrupt process at predetermined intervals.

As shown in FIG. 7, in this process, it is first determined whether or not both the [first condition] and [second condition] are satisfied (step S11, step S12).
If both the [first condition] and the [second condition] are satisfied (step S11: YES and step S12: YES), it is determined that the sealing performance by the sealing member 38 may be reduced. That is, at this time, there is a high possibility that oil leaks from the housing 35 to the intake passage 11 due to the difference between the pressure in the intake passage 11 of the internal combustion engine 10 and the pressure in the housing 35 of the supercharger 30. To be judged.

  In this case, the upper limit speed VL of the valve opening speed of the throttle valve 13 is set to suppress oil leakage from the inside of the housing 35 to the intake passage 11 (step S23). The upper limit speed VL is a constant speed that can accurately suppress an excessive decrease in the impeller back pressure even when the throttle downstream pressure PA1 is reduced based on the results of various experiments and simulations. Is set as required.

  Here, when the throttle upstream pressure PA2 decreases due to an increase in the throttle opening TA while the throttle downstream pressure PA1 is extremely low, the degree of decrease in the throttle upstream pressure PA2 increases as the increase speed of the throttle opening TA increases. growing.

  In this regard, in this process, when both the [first condition] and the [second condition] are satisfied, when not (that is, when either the [first condition] or the [second condition] is not satisfied) In comparison, by setting the upper limit value of the valve opening speed of the throttle valve 13, the valve opening speed of the throttle valve 13 is limited to a low speed. As a result, the degree of decrease in the throttle upstream pressure PA2, and consequently the impeller back pressure, can be suppressed to a low level. Oil leakage to 11 can be suitably suppressed.

  On the other hand, if either [first condition] or [second condition] is not satisfied (step S11: NO or step S12: NO), the sealing performance by the sealing member 38 may be reduced. Judgment is not made. At this time, the opening speed of the throttle valve 13 is not limited by the upper limit speed VL (step S24).

Hereinafter, the effect | action by performing a leakage suppression process is demonstrated, referring FIG.
FIG. 8 is a timing chart showing an example of an execution mode of the leakage suppression process of the present embodiment.
In the example shown in FIG. 8, at time t31, when the throttle opening degree TA becomes smaller when the engine speed is reduced, the throttle downstream pressure PA1 thereafter decreases. Further, the throttle upstream pressure PA2 and the impeller back pressure also decrease as the engine rotation speed and the rotation speed of the rotation shaft 34 of the compressor impeller 31A decrease.

  In this example, as the throttle downstream pressure PA1 and the throttle upstream pressure PA2 decrease, the [first condition] and the [second condition] may be satisfied at time t32 and the sealing performance by the seal member 38 may be reduced. It is determined that there is. Then, over the period when both the [first condition] and the [second condition] are satisfied (time t32 to t34), the opening speed of the throttle valve 13 is limited by the upper limit speed VL.

  In this example, when it is assumed that at time t33, it is assumed that there is no possibility that the sealing performance by the sealing member 38 is deteriorated, the increasing speed of the throttle opening degree TA exceeds the upper limit speed VL (FIG. The mode of operation of the internal combustion engine 10 changes in the manner indicated by the one-dot chain line in FIG.

  At this time, in the apparatus of the present embodiment, since both the [first condition] and the [second condition] are satisfied, as shown by the solid line in FIG. 8, the increase speed of the throttle opening TA is the upper limit speed VL. Thus, the speed at which the low-pressure throttle downstream pressure PA1 is introduced into the portion upstream of the throttle valve 13 is kept low. As a result, the increasing speed of the throttle downstream pressure PA1 is slowed and the decreasing speed of the throttle upstream pressure PA2 and the impeller back pressure is slowed. Therefore, the throttle upstream pressure PA2 and the impeller back pressure are gradually lowered without rapidly decreasing. become. Then, since the intake air amount gradually increases as the throttle opening degree TA increases and the engine speed increases thereafter, the degree of decrease in the throttle upstream pressure PA2 and the impeller back pressure can be kept small. Become.

  According to the apparatus of the present embodiment, since the difference between the impeller back pressure and the internal pressure of the housing 35 of the supercharger 30 can be suppressed in this way, the intake passage from the inside of the housing 35 caused by the pressure difference can be suppressed. Oil leakage to 11 can be suitably suppressed.

  Then, if the [first condition] and [second condition] are not satisfied due to the subsequent increase in the throttle downstream pressure PA1 or the increase in the throttle upstream pressure PA2 (time t34), the upper limit speed of the opening speed of the throttle valve 13 The restriction by VL is released.

As described above, according to the present embodiment, the effect described in the following (3) can be obtained.
(3) When the throttle downstream pressure PA1 is lower than the first determination pressure J1 and the throttle upstream pressure PA2 is lower than the second determination pressure J2, the upper limit value of the valve opening speed of the throttle valve 13 compared to the case where it is not Is set to lower the opening speed of the throttle valve 13. Therefore, oil leakage from the housing 35 of the supercharger 30 into the intake passage 11 can be suitably suppressed.

(Other embodiments)
Each of the above embodiments may be modified as follows.
-Instead of using the value detected by the pressure sensor as the throttle downstream pressure used for the determination in [First Condition] and the throttle upstream pressure used for the determination in [Second Condition] in each embodiment, You may make it use the value estimated based on the driving | running state. Examples of parameters used for estimating the throttle downstream pressure and the throttle upstream pressure include an accelerator operation amount, a throttle opening degree TA, an intake air amount, an engine rotational speed, and a rotational speed of the rotating shaft 34 of the supercharger 30. it can.

  In place of setting the condition that the throttle downstream pressure PA1 detected by the pressure sensor 42 is lower than the first determination pressure J1 as the [first condition] in each embodiment, the throttle opening degree TA is A condition that a situation smaller than the predetermined opening degree has continued for a predetermined time may be set. In short, any condition may be used as long as it is possible to determine that the pressure in the portion downstream of the throttle valve 13 in the intake passage 11 of the internal combustion engine 10 is lower than the first determination pressure J1.

  In the first embodiment, the period for executing the process for suppressing oil leakage (the process of step S14 in FIG. 3) is determined in advance after all of the [first condition] to [third condition] are satisfied. It is good also as a period until predetermined time passes. As the predetermined time, various experiments and simulations are performed for a certain period of time during which the impeller back pressure may be excessively reduced as the engine speed is switched from the deceleration state to the acceleration state. Based on the result, it may be obtained and set in advance.

  The execution period of the process for suppressing oil leakage in the second embodiment (the process of step S14 in FIG. 5) and the process for suppressing oil leakage in the third embodiment (the process of step S23 in FIG. 7) The period of execution may be a period from when both the [first condition] and [second condition] are satisfied until a predetermined time elapses. As the predetermined time, various experiments and simulations are performed for a certain period of time during which the impeller back pressure may be excessively reduced as the engine speed is switched from the deceleration state to the acceleration state. Based on the result, it may be obtained and set in advance.

  In the first and second embodiments, as a process for suppressing oil leakage, the relief pressure of the relief valve 25 is set to a constant pressure (predetermined pressure PL) so as to reduce the oil pressure supplied to the housing 35. However, the relief pressure may be variably set.

  As a setting parameter used for setting the relief pressure in such a device, any value that changes the amount of oil leakage from the supercharger 30 to the intake passage 11 can be adopted. For example, the oil temperature, the internal pressure of the housing 35, The rotational speed of the compressor impeller 31A, the increasing speed of the throttle opening TA, and the like can be employed. The higher the oil temperature, the greater the oil leakage because the viscosity of the oil is lower. Therefore, when the oil temperature is adopted as the setting parameter, the relief pressure of the relief valve 25 may be set to a lower pressure as the oil temperature is higher. Further, the higher the internal pressure of the housing 35 of the supercharger 30 (or the internal pressure of the crankcase communicated with the housing 35), the greater the difference between the impeller back pressure and the housing 35 internal pressure when the impeller back pressure decreases. Therefore, the amount of oil leakage tends to increase. Therefore, when the internal pressure of the housing 35 or the internal pressure of the crankcase is adopted as the setting parameter, the relief pressure of the relief valve 25 may be set to a lower pressure as the internal pressure is higher. Furthermore, the higher the rotational speed of the compressor impeller 31A, the more the blow-by gas increases, so the crankcase internal pressure and the internal pressure of the housing 35 tend to increase, and the amount of oil leakage tends to increase. Therefore, when the rotation speed of the compressor impeller 31A is adopted as the setting parameter, the relief pressure of the relief valve 25 may be set to a lower pressure as the rotation speed of the compressor impeller 31A is higher. Further, the higher the increase rate of the throttle opening TA, the lower the pressure on the impeller back surface, so that the amount of oil leakage tends to increase. Therefore, when the increasing speed of the throttle opening degree TA is adopted as the setting parameter, the relief pressure of the relief valve 25 may be set to a lower pressure as the increasing speed is higher.

  According to such a configuration, the relief pressure of the relief valve 25 can be set to a lower pressure as the amount of oil leakage tends to increase. Therefore, when the amount of oil leakage tends to increase, the relief pressure is lowered to properly suppress oil leakage, while when the amount of oil leakage does not increase so much, the relief pressure is increased to suppress unnecessary deterioration of the lubricating performance. The relief pressure can be set appropriately according to the situation.

  In the third embodiment, as a process for suppressing oil leakage, the upper limit value of the increase speed of the throttle opening TA is not limited to a constant speed (upper limit speed VL), and the upper limit value is variably set. You may make it do.

  As a setting parameter used for setting the upper limit value in such a device, any value that changes the amount of oil leakage from the supercharger 30 to the intake passage 11 can be adopted. For example, the oil temperature, the oil pressure, the housing 35 can be used. The internal pressure, the rotational speed of the compressor impeller 31A, and the like can be employed. Specifically, the higher the oil temperature, the lower the upper limit value is set, or the higher the internal pressure of the housing 35 of the supercharger 30 (or the internal pressure of the crankcase communicated with the housing 35), the higher the upper limit value. May be set to a lower speed, or the upper limit value may be set to a lower speed as the rotational speed of the compressor impeller 31A is higher. Also, the higher the oil pressure, the greater the amount of oil supplied per unit time into the housing 35, and the greater the amount of oil leakage. Therefore, when the oil pressure is adopted as the setting parameter, the upper limit value may be set to a lower speed as the oil pressure is higher.

  According to the above configuration, the upper limit value for the increasing speed of the throttle opening TA can be set to a lower speed as the amount of oil leakage is likely to increase. Therefore, when the amount of oil leakage is likely to increase, the degree of restriction on the increase rate of the throttle opening TA is increased to appropriately suppress the oil leakage. On the other hand, when the amount of oil leakage does not increase so much, the increase rate of the throttle opening TA is limited. The increase speed can be appropriately limited according to the situation, for example, by reducing the degree to suppress an unnecessary decrease in acceleration performance.

  In the first embodiment and the second embodiment, by adopting a variable discharge amount oil pump (for example, an electric oil pump or a swash plate type oil pump) and reducing the discharge amount of the pump, You may make it reduce the pressure of the oil supplied in the housing 35 of the supercharger 30. FIG. In addition, a bypass passage that bypasses the housing 35 and communicates the oil supply passage 23 and the drain passage 26, and a bypass valve that switches between the communication of the oil supply passage 23 and the drain passage 26 through the bypass passage and the shut-off of the communication are provided. At the same time, the pressure of the oil supplied into the housing 35 may be lowered by opening the bypass valve.

  In the third embodiment, instead of limiting the increase speed of the throttle opening degree TA by the upper limit speed VL, the increase speed of the throttle opening degree TA may be decreased by a predetermined speed. Such a configuration can be realized by the configurations described in [Configuration 1] to [Configuration 3], for example. [Configuration 1] In the throttle control, the calculation map (or calculation formula) for calculating the control target value for the throttle opening TA is switched to the calculation map (or calculation formula) for calculating a small opening. [Configuration 2] An arithmetic map (or an arithmetic expression) for calculating a control target value for the operation amount of the throttle motor 14 in the throttle control, and an arithmetic map (or an arithmetic expression) for calculating a value for reducing the driving force of the throttle motor 14 (or Switch to the formula. [Configuration 3] The feedback gain is changed to a small value in the apparatus in which the feedback control of the throttle opening degree TA is executed.

  The present invention is not limited to an internal combustion engine equipped with an exhaust-driven supercharger, but is an engine-driven supercharger in which a rotating shaft of a compressor impeller is drivingly connected to an engine output shaft, or a compressor impeller by an electric motor The present invention can also be applied to an electric supercharger in which the rotating shaft is driven. In short, the present invention can be applied to any internal combustion engine having a supercharger of the type disposed in the intake passage in a state where the compressor impeller can rotate.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Intake passage, 12 ... Throttle mechanism, 13 ... Throttle valve, 14 ... Throttle motor, 15 ... Exhaust passage, 20 ... Oil supply device, 21 ... Oil pan, 22 ... Oil pump, 23 ... Oil supply 24, relief passage, 25 ... relief valve, 26 ... drain passage, 30 ... supercharger, 31 ... compressor, 31A ... compressor impeller, 32 ... turbine, 32A ... turbine wheel, 33 ... coupling part, 34 ... rotating shaft 35 ... Housing, 35A ... Inner surface, 36 ... Radial bearing, 37 ... Thrust bearing, 38 ... Seal member, 40 ... Electronic control device, 41 ... Throttle sensor, 42, 43 ... Pressure sensor.

Claims (4)

Oil is supplied into the turbocharger compressor impeller disposed in the intake passage, a throttle valve disposed downstream of the compressor impeller in the intake passage in the intake air flow direction, and the turbocharger housing. An internal combustion engine control device comprising an oil supply device,
The turbocharger is configured such that the rotation shaft of the compressor impeller is rotatably supported in the housing, and oil leakage to the intake passage through the gap between the rotation shaft and the inner surface of the housing is prevented. A sealing member for sealing is provided,
The pressure in the intake passage downstream of the throttle valve in the intake flow direction is lower than the first determination pressure, and the pressure in the intake passage between the compressor impeller and the throttle valve is lower than the second determination pressure. A control device for an internal combustion engine, wherein the pressure of oil supplied into the housing by the oil supply device is lowered when the pressure is low compared to the case where it is not. Oil is supplied into the turbocharger compressor impeller disposed in the intake passage, a throttle valve disposed downstream of the compressor impeller in the intake passage in the intake air flow direction, and the turbocharger housing. An internal combustion engine control device comprising an oil supply device,
The turbocharger is configured such that the rotation shaft of the compressor impeller is rotatably supported in the housing, and oil leakage to the intake passage through the gap between the rotation shaft and the inner surface of the housing is prevented. A sealing member for sealing is provided,
The pressure in the intake passage downstream of the throttle valve in the intake flow direction is lower than the first determination pressure, and the pressure in the intake passage between the compressor impeller and the throttle valve is lower than the second determination pressure. An internal combustion engine characterized in that when the valve opening speed of the throttle valve is lower and higher than the determination speed, the pressure of the oil supplied into the housing by the oil supply device is made lower than when the throttle valve is not open Engine control device. Oil is supplied into the turbocharger compressor impeller disposed in the intake passage, a throttle valve disposed downstream of the compressor impeller in the intake passage in the intake air flow direction, and the turbocharger housing. An internal combustion engine control device comprising an oil supply device,
The turbocharger is configured such that the rotation shaft of the compressor impeller is rotatably supported in the housing, and oil leakage to the intake passage through the gap between the rotation shaft and the inner surface of the housing is prevented. A sealing member for sealing is provided,
The pressure in the intake passage downstream of the throttle valve in the intake flow direction is lower than the first determination pressure, and the pressure in the intake passage between the compressor impeller and the throttle valve is lower than the second determination pressure. A control apparatus for an internal combustion engine, characterized in that the opening speed of the throttle valve is reduced when the engine speed is low, compared with the case where it is not. The control apparatus for an internal combustion engine according to claim 3,
The control apparatus for an internal combustion engine is characterized in that the valve opening speed is reduced by setting an upper limit value of the valve opening speed of the throttle valve.

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