JP2011117345A - Supercharging system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supercharging system of an internal combustion engine, enhancing an estimation accuracy for estimating whether or not coking is generated, and estimating an amount of deposits adhered in a compressor. <P>SOLUTION: The supercharging system includes: a movable vane 21 disposed to be movable between a storage position housed in a wall face forming a part of a diffuser part 16, and a projection position projecting from the wall face to cross the diffuser part 16; an actuator 19 driving the movable vane 21; and a compressor 10a disposed to an intake passage 3 of the internal combustion engine 1. The supercharging system further includes a stroke sensor 24 detecting a stroke amount of a rod 19a of an actuator 19. When a predetermined switching condition is satisfied and the actuator 19 moves the movable vane 21 from the storage position to the projection position, the amount of deposits C adhered to the diffuser part 16 is estimated based on the stroke amount detected by the stroke sensor 24. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a supercharging system for an internal combustion engine provided with a compressor provided in an intake passage of the internal combustion engine and having a retractable movable vane provided in a diffuser section.

  2. Description of the Related Art There is known a supercharging device in which a compressor having vanes provided in a diffuser section is provided in an intake passage and the internal combustion engine is supercharged by this compressor. In the intake passage, exhaust gas is recirculated from the exhaust passage or blow-by gas is introduced from the engine body. As is well known, exhaust gas and blow-by gas contain oil and unburned fuel, and when these are sucked into the compressor and heated, they may adhere to the inside of the compressor and cause coking. When this coking occurs, it becomes difficult for the intake air to flow or the flow of the intake air changes, which may reduce the efficiency of the compressor and reduce the supercharging performance. In the compressor, since the flow velocity of the intake air once decreases in the diffuser portion, coking is likely to occur in the diffuser portion. Therefore, a bypass passage that bypasses the diffuser section and an opening / closing member that opens and closes the bypass passage are provided, and when the efficiency of the compressor falls below a predetermined judgment value, when the intake air temperature rises above a predetermined temperature, There is known a supercharger that opens a bypass passage by determining that coking has occurred when the pressure of the oil rises above a predetermined pressure (see Patent Document 1).

JP 2009-108680 A

  In the apparatus of Patent Document 1, it is determined whether or not coking has occurred based on the efficiency of the compressor, the temperature of the intake air, or the pressure of the intake air. In this case, since the occurrence of coking is indirectly determined, there is a risk of erroneously determining whether or not coking has occurred. Moreover, in the apparatus of patent document 1, the quantity of the deposit | attachment adhering in the compressor is not estimated.

  Therefore, the present invention provides a supercharging system for an internal combustion engine that can improve the estimation accuracy of whether or not coking has occurred and can estimate the amount of deposits adhering to the compressor. Objective.

  A supercharging system for an internal combustion engine according to the present invention includes a housing that houses a compressor wheel and supports the compressor wheel so as to be rotatable about an axis, and a spiral-shaped housing provided on the outer periphery of the compressor wheel. The scroll, a diffuser portion provided as a passage space leading to the scroll from the outlet side of the compressor wheel, a storage position accommodated in a wall surface forming a part of the diffuser portion, and the diffuser portion so as to cross the diffuser portion An internal combustion engine having a movable vane movably provided between a projecting position projecting from a wall surface, and a drive means for driving the movable vane, and comprising a compressor provided in an intake passage of the internal combustion engine In the supercharging system, a moving amount detecting means for detecting a distance traveled by the movable vane, Control means for controlling the operation of the driving means so that the movable vane moves from the retracted position to the protruding position when the switching condition is satisfied, and the predetermined switching condition is satisfied and the driving means is Estimating means for estimating the amount of adhering matter adhering to the diffuser section based on the moving distance of the movable vane detected by the moving amount detecting means when the movable vane is moved. 1).

  When caulking occurs in the diffuser part, deposits adhere to the surface of the wall surface forming the diffuser part. This deposit is sandwiched between the movable vane and the wall surface of the diffuser when the movable vane is protruded from the storage position into the diffuser, so that the moving distance of the movable vane changes. And this movement distance becomes small, so that there are many amounts of deposits. Thus, the moving distance of the movable vane is directly related to the deposit adhered by caulking. According to the supercharging system of the present invention, since the amount of deposits adhering to the diffuser portion is estimated based on the moving distance of the movable vanes, it is possible to improve the estimation accuracy as to whether or not coking has occurred. it can. Further, as described above, the moving distance of the movable vane becomes smaller as the amount of deposits increases, so the amount of deposits adhering in the compressor can be estimated from the moving distance of the movable vanes.

  In one form of the supercharging system of this invention, you may further provide the condition change means to change the said predetermined switching condition based on the quantity of the deposit | attachment estimated by the said estimation means (Claim 2). When deposits adhere, the flow passage cross-sectional area of the diffuser changes, and the gas flow rate at which surging occurs, the so-called surge limit, changes. For this reason, if the movable vane is controlled under the same conditions as when there is no deposit when the deposit is adhered, surging may occur in the compressor depending on the amount of deposit. In this embodiment, since the switching condition is changed according to the amount of deposits, surging can be prevented from occurring in the compressor. Further, by changing the switching condition in this way, it is possible to prevent the supercharging performance from changing suddenly when the position of the movable vane is switched. Therefore, it is possible to prevent a sudden change in the torque of the internal combustion engine. Moreover, this can suppress the deterioration of drivability.

  In this embodiment, the predetermined switching condition is satisfied when a gas flow rate sucked into the compressor is equal to or lower than a predetermined flow rate, and the condition changing unit is configured to perform the predetermined change based on the amount of deposit estimated by the estimation unit. The flow rate may be changed (claim 3). In this way, when the position of the movable vane is switched based on the gas flow rate sucked into the compressor, the switching condition can be changed according to the amount of deposits by changing the predetermined flow rate that is the determination criterion. it can.

  Further, the condition changing means may decrease the predetermined flow rate as the amount of deposit estimated by the estimating means increases. The surge limit of the compressor with the movable vane protruding from the diffuser portion changes to a smaller gas flow rate as the flow passage cross-sectional area of the diffuser portion becomes smaller. That is, as the amount of deposit increases, the surge limit changes to the side where the gas flow rate is smaller. In this embodiment, the larger the amount of deposits, the smaller the predetermined flow rate. Therefore, even if deposits adhere to the diffuser, it is possible to control the switching of the movable vanes while suppressing surging from occurring in the compressor.

  As described above, according to the supercharging system for an internal combustion engine of the present invention, the amount of deposit is estimated based on the moving distance of the movable vane that is directly related to the amount of deposit in the compressor. The estimation accuracy of whether or not coking has occurred can be improved. Further, since the moving distance of the movable vane becomes smaller as the amount of the deposit is larger, the amount of the deposit can be estimated from the moving distance of the movable vane.

The figure which shows schematically the internal combustion engine in which the supercharging system which concerns on one form of this invention was integrated. The figure which shows the cross section of the compressor of FIG. The figure which shows the characteristic curve of the compressor of FIG. The figure which shows the characteristic curve of the compressor when caulking generate | occur | produces. The flowchart which shows the movable vane control routine which ECU performs.

  FIG. 1 schematically shows an internal combustion engine incorporating a supercharging system according to an embodiment of the present invention. An internal combustion engine (hereinafter sometimes referred to as an engine) 1 in FIG. 1 is mounted as a driving power source for a vehicle, and includes an engine main body 2, an intake passage 3 connected to the engine main body 2, and an exhaust gas. And a passage 4. The intake passage 3 is provided with a compressor 10 a of the turbocharger 10, an intercooler 5 for cooling the intake air, and a throttle valve 6 for opening and closing the intake passage 3. In the exhaust passage 4, a turbine 10b of the turbocharger 10 is provided. The exhaust passage 4 on the downstream side of the turbine 10 b and the intake passage 3 on the upstream side of the compressor 10 a are connected by an EGR passage 7 for returning a part of the exhaust from the exhaust passage 4 to the intake passage 3. Although not shown, the engine body 2 and the intake passage 3 upstream of the compressor 10a are connected to each other through a blowby gas reduction passage for discharging blowby gas from the engine body 2 to the intake passage 3.

  FIG. 2 shows a cross-sectional view of the compressor 10a. As shown in FIG. 2, the compressor 10 a includes a compressor housing 11 and a compressor wheel 13 that is accommodated in the compressor housing 11 and is supported by the rotary shaft 12 so as to be rotatable about the axis Ax. The compressor housing 11 is provided as a wheel space 14 that houses the compressor wheel 13, a spiral scroll 15 provided on the outer periphery of the wheel chamber 14, and a passage space that leads from the outlet side 13 a of the compressor wheel 13 to the scroll 15. And a diffuser section 16. The compressor wheel 13 is connected to the rotating shaft 12 so as to rotate integrally with a turbine wheel (not shown) of the turbine 10b. In addition, since these parts may be the same as the compressor 10a of the well-known turbocharger 10, detailed description is abbreviate | omitted.

  As shown in this figure, the compressor 10a is provided with a movable vane mechanism 17. The movable vane mechanism 17 includes a movable part 18 provided so as to be movable in the direction of the axis Ax, and an actuator 19 as a driving means for driving the movable part 18. The movable portion 18 includes an annular base plate 20 and a plurality of vanes 21 (only one is shown in FIG. 2) provided on the base plate 20. The plurality of vanes 21 are provided on the base plate 20 so as to be arranged at equal intervals on the same circumference. In addition, as shown in this figure, each vane 21 is provided so as to extend in the axis Ax direction from the same surface of the base plate 20. In addition, since the cross-sectional shape of the vane 21 may be the same as the well-known thing provided in the compressor 10a, detailed description is abbreviate | omitted.

  The compressor housing 11 is provided with a storage chamber 22 so as to line up with the diffuser portion 16 in the axis Ax direction. The diffuser portion 16 and the storage chamber 22 are separated by a partition wall 23 that forms a part of the diffuser portion 16. The partition wall 23 is provided with through holes 23a corresponding to the plurality of vanes 21, and the movable portion 18 is accommodated in the accommodating chamber 22 so that each vane 21 is inserted into the through hole 23a. The movable portion 18 is accommodated so as to be movable between a storage position where each vane 21 is accommodated in the partition wall 23 and a protruding position where each vane 21 projects from the partition wall 23 so as to cross the diffuser portion 16. It is accommodated in the chamber 22. In the storage position, the tip of each vane 21 is flush with the partition wall 23. In the protruding position, the tip of each vane 21 is in contact with the facing surface 16 a facing the partition wall 23.

  The actuator 19 includes a rod 19a whose tip is connected to the movable portion 18, and a drive portion 19b for expanding and contracting the rod 19a. The drive unit 19b is the same as that provided in a known air cylinder. The actuator 19 drives the movable portion 18 between the retracted position and the protruding position by expanding and contracting the rod 19a. The actuator 19 is provided with a stroke sensor 24 as movement amount detecting means for outputting a signal corresponding to the stroke amount of the rod 19a. Since this stroke sensor may be a known one, detailed description thereof is omitted.

  The operation of the actuator 19 is controlled by an engine control unit (ECU) 30. The ECU 30 is configured as a computer including a microprocessor and peripheral devices such as RAM and ROM necessary for its operation, and controls the opening degree of the throttle valve 6 and the like based on output signals from various sensors. It is a well-known computer unit which controls the driving | running state of. As shown in FIG. 1, the ECU 30 corresponds to, for example, an air flow meter 31 that outputs a signal corresponding to the intake air amount, and an intake pressure of an intake manifold 3 a that forms a part of the intake passage 3, that is, a supercharging pressure. A supercharging pressure sensor 32 that outputs a signal to be connected is connected. In addition, a stroke sensor 24 is also connected to the ECU 30. Various other sensors are connected to the ECU 30, but their illustration is omitted.

  A control method of the movable vane mechanism 17 by the ECU 30 will be described with reference to FIGS. 3 and 4. 3 and 4 show characteristic curves of the compressor 10a. In addition, the pressure ratio of these figures is a ratio of the pressure of the intake air at the inlet of the compressor 10a and the pressure of the intake air at the outlet of the compressor 10a. In these drawings, common parts are denoted by the same reference numerals. Solid lines S1a and S1b in these figures indicate surge lines when the movable portion 18 is in the retracted position, that is, when the vane 21 is not present in the diffuser portion 16. Further, solid lines S2a and S2b in these drawings indicate surge lines when the movable portion 18 is in the protruding position, that is, when the diffuser portion 16 has the vane 21 (hereinafter, sometimes referred to as a protruding surge line). ing. These solid lines S2a and S2b indicate surge lines when no coking occurs in the compressor 10a and there is no deposit in the compressor 10a. The alternate long and short dash line E in these drawings may be referred to as an operating line of the compressor 10a when the engine 1 is operating at full load, that is, the throttle opening is fully open (hereinafter referred to as engine operating line). ). As shown in FIG. 3, in the compressor 10a, when the intake air amount is the first flow rate G1, the engine operating line E and the protruding surge line S2b intersect. Therefore, the ECU 30 controls the operation of the actuator 19 so that the movable portion 18 moves to the storage position when the intake air amount is equal to or greater than the first flow rate G1. On the other hand, when the intake air amount is less than the first flow rate G1, the operation of the actuator 19 is controlled so that the movable portion 18 moves to the protruding position. That is, the first flow rate G1 is used as a determination value when determining the switching of the position of the movable portion 18.

  In the engine 1, exhaust gas is recirculated or blow-by gas is introduced upstream of the compressor 10a. For this reason, coking is caused by unburned fuel or oil that has flowed into the compressor 10a, and the deposit C (see FIG. 2) may adhere to the diffuser portion 16. When coking occurs in the compressor 10a in this way, the cross-sectional area of the flow path becomes small and the surge line changes. Dashed lines S3a and S3b in FIG. 3 show an example of a surge line at the time of protrusion when coking is generated in the compressor 10a. As shown in this figure, when coking occurs in the compressor 10a, the surge line at the time of protrusion changes to the side where the intake air amount is small. This change is determined according to the amount of deposit C adhering to the compressor 10a. As shown by the arrow A in the figure, the surge line at the time of protrusion has a smaller intake air amount as the amount of deposit C increases (see FIG. To the left of 3). In the example shown in this figure, when the intake air amount is the second flow rate G2, the engine operation line E and the protruding surge line S3b intersect. Therefore, in order to prevent surging of the compressor 10a, it is necessary to move the movable portion 18 to the storage position when the intake air amount is equal to or greater than the second flow rate G2. Therefore, the ECU 30 changes the determination value used for controlling the position of the movable portion 18 from the first flow rate G1 to the second flow rate G2.

  As described above, the change of the surge line at the time of protrusion is determined according to the amount of the deposit C. Therefore, when changing the determination value in this way, the ECU 30 first estimates the amount of the deposit C, and sets the determination value based on the estimated amount of the deposit C. When coking occurs in the compressor 10a, the deposit C is sandwiched between the tip of the vane 21 and the facing surface 16a when the vane 21 is protruded into the diffuser portion 16 as shown in FIG. Therefore, even if the movable part 18 is moved from the retracted position to the protruding position side, it does not reach the protruding position and stops halfway. That is, the moving distance of the movable part 18 becomes small. And the moving distance of the movable part 18 becomes small, so that the amount of the deposit | attachment C is large. Further, the moving distance of the movable portion 18 is equal to the stroke amount of the rod 19 a of the actuator 19. Thus, the stroke amount of the rod 19a when the movable vane 16 is driven from the retracted position to the protruding position side is directly related to the amount of the deposit C. Therefore, the ECU 30 acquires the stroke amount of the rod 19a when the movable portion 18 in the retracted position is moved to the protruding position side, and estimates the adhesion amount based on the stroke amount. In this estimation, the relationship between the stroke amount of the rod 19a and the amount of the deposit C may be obtained in advance by experiments or the like and stored in the ROM of the ECU 30 as a map. Next, the ECU 30 sets a determination value based on the estimated amount of deposit C. The determination value may be set to an intake air amount at which the protruding surge line and the engine operating line intersect. Therefore, the relationship between the amount of deposit C and the amount of intake air at which the surge line at the time of protrusion when the amount of deposit adheres is obtained as a map in the ROM of the ECU 30 as a map by an experiment or the like. The determination value may be set based on this map. This determination value is stored in the RAM of the ECU 30, and is used when determining whether or not the position of the movable portion 18 should be switched.

  The broken lines S4a and S4b in FIG. 4 indicate the surge line at the time of protrusion when the deposit C further adheres in the compressor 10a and the surge line at the time of protrusion changes to a smaller intake air amount side. If the surge line at the time of protrusion changes to this position, there is a possibility that surging or excessive rotation in which the rotational speed of the compressor wheel 13 excessively increases every time the position of the movable valve 18 is switched. Therefore, the ECU 30 prohibits the operation of the actuator 19 when the moving distance of the movable portion 18 is equal to or less than a preset lower limit value, maintains the state in which the vane 21 protrudes into the diffuser portion 16, and the intake air amount Restricts the operation of the throttle valve 6 so as to be limited to a predetermined amount or less. Hereinafter, this state may be referred to as a retreat operation.

  FIG. 5 shows a movable vane control routine that the ECU 30 repeatedly executes at a predetermined cycle during operation of the engine 1 in order to control the operation of the movable vane mechanism 17 by the control method described above. By executing this control routine, the ECU 30 functions as the control means of the present invention.

  In the control routine of FIG. 5, the ECU 30 first acquires the operating state of the engine 1 in step S11. As the operating state of the engine 1, for example, an intake air amount, a supercharging pressure, and the like are acquired. In the next step S12, the ECU 30 determines whether or not the engine 1 is being operated in a retreat operation. If it is determined that the evacuation operation is being performed, the current control routine is terminated. On the other hand, if it is determined that the retreat operation is not being performed, the process proceeds to step S13, where the ECU 30 determines whether a switching condition for moving the position of the movable portion 18 from the storage position to the protruding position is satisfied. As described above, this switching condition is determined to be satisfied when the intake air amount is less than the determination value stored in the RAM of the ECU 30. If it is determined that the switching condition is not satisfied, the process proceeds to step S14, where the ECU 30 executes storage control for controlling the operation of the actuator 19 so that the movable portion 18 moves from the protruding position to the storage position. In addition, when the movable part 18 has already moved to the storage position, the state is maintained. Thereafter, the current control routine is terminated.

  On the other hand, if it is determined that the switching condition is satisfied, the process proceeds to step S15, and the ECU 30 determines whether or not the movable portion 18 is in the storage position. If it is determined that the movable portion 18 is not in the storage position, the current control routine is terminated. On the other hand, if it is determined that the movable portion 18 is in the storage position, the process proceeds to step S16, and the ECU 30 executes protrusion control for controlling the operation of the actuator 19 so that the movable portion 18 moves from the storage position to the protrusion position. In the subsequent step S17, the ECU 30 acquires the stroke amount of the rod 19a when the protrusion control is executed based on the output signal of the stroke sensor 24. In the next step S18, the ECU 30 determines whether or not the stroke amount of the rod 19a is less than a preset allowable value. This allowable value is set to prevent useless change of the determination value. As is well known, the sensor has a detection error. Moreover, the surge line at the time of protrusion when the deposit C is small is almost the same as the surge line at the time of protrusion when there is no deposit C. Therefore, the allowable value may be set as appropriate according to, for example, the flow path cross-sectional area of the diffuser unit 16 and the detection error of the stroke sensor 24. If it is determined that the stroke amount is greater than or equal to the allowable value, the current control routine is terminated.

  On the other hand, if it is determined that the stroke amount is less than the allowable value, the process proceeds to step S19, where the ECU 30 determines whether or not the stroke amount is less than a preset lower limit value. As the lower limit value, for example, there is set a stroke amount at which surging or over-rotation of the compressor wheel 13 may occur each time the position of the movable valve 18 is switched due to a large amount of deposits. When it is determined that the stroke amount is less than the lower limit value, the process proceeds to step S20, and the ECU 30 controls the operations of the movable vane mechanism 17 and the throttle valve 6 so that the engine 1 is operated in the retreat operation. Thereafter, the current control routine is terminated.

  On the other hand, if it is determined that the stroke amount is equal to or greater than the lower limit value, the process proceeds to step S21, and the ECU 30 estimates the amount of deposit C attached to the compressor 10a based on the stroke amount. By executing this process, the ECU 30 functions as the estimation means of the present invention. In the next step S22, the ECU 30 executes a switching condition changing process. In this switching condition change process, first, a determination value is set based on the estimated amount of deposit C. Therefore, by executing this process, the ECU 30 functions as the condition changing means of the present invention. As described above, this determination value is stored in the RAM of the ECU 30 and is maintained until this process is executed next time. Further, in this process, in order to prevent surging of the compressor 10a, the target boost pressure set according to the operating state of the engine 1 is corrected in the direction of decreasing. Thereafter, the current control routine is terminated.

  As described above, according to this supercharging system, the amount of deposit C adhering in the compressor 10a is estimated based on the stroke amount of the rod 19a. As described above, since the stroke amount of the rod 19a is directly related to the amount of the deposit C, it is possible to improve the estimation accuracy as to whether or not coking is occurring in the compressor 10a. Further, since the stroke amount decreases as the amount of the deposit C increases, the amount of the deposit C can be estimated based on the stroke amount. And in this supercharging system, since the judgment value is changed according to the estimated amount of deposit C, it is possible to suppress the occurrence of surging in the compressor 10a. Further, when the determination value is changed, the target supercharging pressure is corrected so as to decrease, so that the temperature of the intake air in the compressor 10a can be reduced, thereby suppressing the deterioration of coking.

  The present invention is not limited to the above-described form and can be implemented in various forms. For example, the mechanism for driving the movable vane in the axial direction is not limited to that driven by a pressure difference. For example, the movable vane may be driven using an electric motor. Further, the means for detecting the moving distance of the movable vane is not limited to the stroke sensor. For example, when the power of the electric motor is transmitted to the movable vane via the link mechanism or the cam mechanism, a sensor that detects the rotation angle of the cam mechanism or the link mechanism is provided. And the movement distance of a movable vane may be detected based on the angle etc. which the cam mechanism or the link mechanism moved when the movable vane was driven.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Intake passage 10a Compressor 11 Compressor housing 13 Compressor wheel 15 Scroll 16 Diffuser part 19 Actuator (drive means)
21 Movable vane 24 Stroke sensor (movement amount detection means)
30 Engine control unit (control means, estimation means, condition change means)
Ax Axis C Deposit

Claims (4)

A housing that houses the compressor wheel and supports the compressor wheel so as to be rotatable about an axis, a spiral scroll provided on the housing so as to be disposed on the outer periphery of the compressor wheel, and the outlet from the compressor wheel Movement between a diffuser portion provided as a passage space leading to the scroll, a storage position accommodated in a wall surface forming a part of the diffuser portion, and a protruding position protruding from the wall surface so as to cross the diffuser portion In a supercharging system for an internal combustion engine having a movable vane provided in a possible manner and a drive means for driving the movable vane, and including a compressor provided in an intake passage of the internal combustion engine,
A moving amount detecting means for detecting a distance traveled by the movable vane, and a control for controlling an operation of the driving means so that the movable vane moves from the retracted position to the protruding position when a predetermined switching condition is satisfied. And attached to the diffuser section based on the moving distance of the movable vane detected by the movement amount detecting means when the predetermined switching condition is satisfied and the driving means moves the movable vane. An internal combustion engine supercharging system comprising: estimation means for estimating a kimono amount.   2. The supercharging system for an internal combustion engine according to claim 1, further comprising condition changing means for changing the predetermined switching condition based on the amount of deposit estimated by the estimating means. The predetermined switching condition is satisfied when a gas flow rate sucked into the compressor is less than a predetermined flow rate,
The supercharging system for an internal combustion engine according to claim 2, wherein the condition changing means changes the predetermined flow rate based on the amount of deposits estimated by the estimating means.   The supercharging system for an internal combustion engine according to claim 3, wherein the condition changing unit decreases the predetermined flow rate as the amount of deposit estimated by the estimating unit increases.

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