JP5527306B2 - Variable capacity turbocharger - Google Patents

Description

  The present invention relates to a variable displacement turbocharger including a variable nozzle unit for changing the capacity of exhaust gas discharged from a scroll passage of a turbine housing to a discharge port via a turbine wheel.

  Conventionally, as a turbocharger equipped in a diesel engine or the like, a variable displacement turbocharger having a variable capacity on the turbine side is known (see, for example, Patent Document 1).

  In this type of turbocharger, a variable nozzle unit whose flow area or throat area is variable is disposed in a communication path that connects a scroll path of a turbine housing and an exhaust port to an exhaust pipe.

  This variable nozzle unit changes the posture of a plurality of nozzle vanes (also referred to as movable vanes) in the low engine speed range to reduce the spacing (flow area or throat area) between nozzle vanes adjacent in the circumferential direction. As a result, the flow rate of the exhaust gas is increased, whereby a high boost pressure is obtained from the low engine speed range.

  In Patent Document 1, the paragraph 0006 states that “the fuel or gas in the vortex chamber enters the link chamber through a gap such as a pin for operating the nozzle due to a pressure difference between the vortex chamber of the turbine housing and the link chamber. There is a problem that the accumulated fuel or gas hinders the sliding of the link mechanism and deteriorates the controllability ". The link mechanism is for transmitting the power generated by the actuator to the link plate of the variable nozzle unit to rotate the link plate, and is arranged in the link chamber.

  Therefore, in Patent Document 1, in order to suppress the movement of fuel from the vortex chamber to the link chamber, a connecting path that connects the vortex chamber and the link chamber is provided, and the pressure difference between the vortex chamber and the link chamber is set. It is made small (refer claim 1, paragraphs 0009 and 0041). In addition, in paragraph 0009 of Patent Document 1, “Because this connection path is disposed so as to protrude into the vortex chamber, fuel attached to the vortex chamber can be prevented from entering the connection path”. Have been described.

JP 2006-233940 A

  In the conventional example according to Patent Document 1, since the connecting path is always opened and is not opened or closed, exhaust gas leaks from the vortex chamber to the link chamber, and the supercharging efficiency decreases. There are concerns.

  In view of such circumstances, the present invention provides a variable displacement turbocharger including a variable nozzle unit for changing a capacity for discharging exhaust gas from a scroll passage of a turbine housing to a discharge port through a turbine wheel. The object is to make it possible to remove the deposit (deposit) even if unburned gas contained in the gas adheres to and accumulates on the movable part.

  A variable capacity turbocharger according to the present invention includes a variable nozzle unit for changing a capacity of exhaust gas exhausted from a scroll passage of a turbine housing to a discharge port through a turbine wheel. First and second nozzle plates arranged to face each other so as to form a flow path from the scroll passage to the discharge port, nozzle vanes provided at several circumferential positions between the first and second nozzle plates, and all nozzle vanes An actuator for changing the area of the flow path by changing the posture of the actuator at once, and in a region adjacent to the scroll passage, a part of the movable part for power transmission provided in the actuator is disposed. An annular space is provided in communication with the scroll passage. The first nozzle plate is attached to the portion so as to close the communication portion, and the first nozzle plate has a through-hole for allowing inflow of exhaust gas from the scroll passage to the annular space. And an opening / closing portion for opening or closing the through hole is provided in a part of the movable part.

  In this configuration, unburned gas contained in the exhaust gas flowing through the scroll passage may leak into the annular space from the mounting gap of the first nozzle plate with respect to the communicating portion. If such a leak is repeated, the unburned gas will accumulate on the movable part disposed in the annular space, and this deposit (deposit) hinders the movement of the movable part. It can be.

  On the other hand, in the configuration of the present invention, when the through hole is opened, a part of the high-temperature exhaust gas flowing through the scroll passage is caused to flow into the annular space through the through hole. In this way, the heat of the high-temperature exhaust gas flowing into the annular space acts to vaporize and disappear the deposit that has adhered and deposited on the movable part. As a result, the movement of the movable part can be maintained satisfactorily over a long period of time, so that the reliability of the variable capacity turbocharger can be improved. Moreover, since the said through-hole is not always open | released, it becomes possible to suppress the loss of supercharging efficiency.

  In addition, when the movable part provided in the actuator is moved in order to change the supercharging capability, the through hole is opened or closed in conjunction with the movement. It is possible to suppress the increase in equipment cost.

  Preferably, the opening / closing part opens the through hole when the movable part is disposed at a position that maximizes the flow path area, while the movable part is at a position that minimizes the flow path area. The movable part is provided so as to close the through hole when arranged.

  Thus, even if the through hole is opened at the position where the flow path area is maximized by the movable part, the amount of exhaust gas flowing into the annular space from the scroll passage through the through hole is small. Since the total flow rate of the exhaust gas flowing through the scroll passage is small, the loss of the supercharging capability can be minimized.

  Preferably, the actuator is a unison ring formed of an annular plate that is arranged in a state of being rotatably supported at a position adjacent to the first nozzle plate and in which the nozzle vane is tiltably supported at several circumferential positions. A drive source that generates power necessary to rotate the unison ring from a position that maximizes the flow path area to a position that minimizes the flow path area; and the power generated by the drive source. A link mechanism for transmitting the rotational power to the ring as a rotational power, and a final power transmission member for directly transmitting the rotational power to the movable part in the link mechanism is a circumferential direction of the movable part comprising the annular plate. Arranged in a predetermined phase, and the through hole is installed corresponding to an arrangement position of the final power transmission member, and the unison ring and the outermost ring are arranged. Power transmission member is a movable part.

  Here, the movable parts are clarified and elements for operating the movable parts are clarified. In this configuration, even if the unburned gas adheres to and accumulates on the movable part (unison ring and final power transmission member), when the through hole is opened, it flows into the annular space from the scroll passage through the through hole. High temperature exhaust gas comes into contact with the moving parts immediately after the inflow. For this reason, deposits adhering to and accumulating on the movable parts (unison ring and final power transmission member) are easily vaporized and disappeared by the high-temperature exhaust gas.

  Preferably, the variable nozzle unit further includes a control unit that controls the actuator, and the control unit adds the exhaust gas purification fuel to the movable part on the upstream side of the scroll passage. Estimating means for estimating the amount of deposit deposited and deposited, and after determining that the estimated value by the estimating means exceeds a predetermined value, when determining that the flow rate of exhaust gas flowing through the scroll passage exceeds a predetermined value And a first processing means for operating the movable part so as to open the through hole by the actuator.

  In this configuration, the movable part can be automatically operated so as to open the through hole. Further, it becomes unnecessary to operate the movable part more than necessary.

  Preferably, the variable nozzle unit further includes a control unit that controls the actuator, and the control unit adds the exhaust gas purification fuel to the movable part on the upstream side of the scroll passage. Estimating means for estimating the amount of deposit deposited and deposited, and after determining that the estimated value by the estimating means exceeds a predetermined value, it is determined that the accelerator pedal is turned off so that the exhaust gas purification fuel is not added. And a first processing means for operating the movable part so as to open the through hole by the actuator when it is determined that the flow rate of the exhaust gas flowing through the scroll passage exceeds a predetermined value.

  In this configuration, since the movable part is operated so as to open the through hole when the accelerator pedal is turned off, the exhaust gas is contained in the exhaust gas when the through hole is opened. Disappear. For this reason, even if exhaust gas flows into the annular space from the through hole, it is possible to prevent excess fuel from remaining in the annular space. In this way, the through hole can be opened at an optimal timing.

  Preferably, the control unit integrates the opening times of the through holes, and operates the movable part to close the through holes with the actuator when it is determined that the integrated value exceeds a predetermined value. 2 processing means is further included.

  In this configuration, the movable part can be operated so as to close the through hole at an optimal timing.

  Preferably, the variable displacement turbocharger further includes a bearing housing for rotatably supporting a common rotating shaft that integrally rotates the turbine wheel and the compressor impeller, and the turbine housing includes the bearing housing. In the axially intermediate region of the outer periphery of the bearing, it is coupled to a radially outward flange provided near the turbine, and the annular space is provided at a coupling portion between the flange of the bearing housing and the turbine housing. Here, the place where the annular space is provided is clarified.

  Preferably, the opening / closing part is a leaf spring fixed to the movable part and elastically pressed against the first nozzle plate.

  Here, the opening / closing part is specified. According to this specification, when the through hole of the first nozzle plate is closed, there is no problem that the opening / closing part made of the leaf spring is separated from the first nozzle plate.

  The present invention relates to an unburned gas contained in an exhaust gas in a variable capacity turbocharger including a variable nozzle unit for enabling a change in the capacity of exhaust gas discharged from a scroll passage of a turbine housing to an exhaust port through a turbine wheel. Even if it adheres to and accumulates on the movable part, it is possible to remove this deposit (deposit).

1 is a cross-sectional view showing a schematic configuration of an embodiment of a variable capacity turbocharger according to the present invention. It is sectional drawing which expands and shows the upper half of the variable nozzle unit of FIG. It is a figure which shows the outer surface of the unison ring of the variable nozzle unit of FIG. 1, and has shown the state which enlarged the nozzle vane opening degree. It is a figure which shows the inner surface of the 1st nozzle plate of the variable nozzle unit of FIG. 1, and has shown the state which enlarged the nozzle vane opening degree. It is a figure which shows the outer surface of the unison ring of the variable nozzle unit of FIG. 1, and has shown the state which made the nozzle vane opening degree small. It is a figure which shows the inner surface of the 1st nozzle plate of the variable nozzle unit of FIG. 1, and has shown the state which made the nozzle vane opening degree small. It is a perspective view which shows a part of link mechanism of FIG. It is a perspective view which decomposes | disassembles and shows a part of link mechanism of FIG. It is the figure which looked at a pair of plate and unison ring of FIG. 1 from the top, and has shown the state which has obstruct | occluded the through-hole. It is the figure which looked at a pair of plate and unison ring of FIG. 1 from the top, and has shown the state which has opened the through-hole. It is a flowchart for demonstrating operation | movement of the variable nozzle unit shown in FIG. It is a graph which shows the case where the through-hole is obstruct | occluded within the normal rotation angle area | region which uses the unison ring 21 for normal control of a supercharging capability, and a through-hole is open | released outside the said normal rotation angle area | region. It is a graph which shows the case where a through-hole is open | released or obstruct | occluded in the normal rotation angle area | region which uses the unison ring 21 for normal control of a supercharging capability.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  1 to 12 show an embodiment of the present invention. The illustrated variable displacement turbocharger 1 is attached to an internal combustion engine (not shown). As shown in FIGS. 1 to 8, the variable capacity turbocharger 1 includes a turbine wheel 2, a compressor impeller 3, a bearing housing 4, a turbine housing 5, a compressor housing 6, a variable nozzle unit 7, and the like.

  The turbine wheel 2 is integrally formed at one axial end of the turbine shaft 2a, and the compressor impeller 3 is integrally attached to the other axial end of the turbine shaft 2a. The turbine shaft 2a is inserted into the center hole of the bearing housing 4 so as to be rotatable via two radial bearings 8A and 8B.

  The two radial bearings 8A and 8B are substantially cylindrical slide bearings called metals and bushes, and are in a floating state in a state where displacement in the axial direction is restricted.

  A turbine housing 5 is attached to one end of the bearing housing 4 in the axial direction, and a compressor housing 6 is attached to the other end of the bearing housing 4 in the axial direction. The turbine wheel 2 is accommodated in the turbine housing 5, and the compressor impeller 3 is accommodated in the compressor housing 6.

  The turbine housing 5 is provided with a scroll passage 5a for turning the exhaust gas, and a discharge port 5b for discharging the exhaust gas in the scroll passage 5a to an exhaust pipe (not shown) via the turbine wheel 2.

  The compressor housing 6 has an inlet 6a through which intake air from an intake system (not shown) is introduced toward the compressor impeller 3 and intake air whose pressure is increased by the rotation of the compressor impeller 3 (not shown). And a delivery passage 6b for delivery to the vehicle.

  The turbine wheel 2 is rotated using the energy of the exhaust gas discharged from the internal combustion engine to an exhaust manifold (not shown), and fresh air having a pressure higher than the atmospheric pressure is generated by the compressor impeller 3 that rotates integrally with the turbine wheel 2. The air is supplied from an intake manifold (not shown) into a combustion chamber (not shown).

  The variable nozzle (VN) unit 7 can change the capacity for discharging exhaust gas from the scroll passage 5a of the turbine housing 5 through the turbine wheel 2 to the discharge port 5b, as shown in FIGS. Further, a pair of first and second nozzle plates 11 and 12, a plurality of nozzle vanes 13, an actuator 20, a control unit 100, and the like are provided.

  The first and second nozzle plates 11 and 12 are annular plates and are arranged to face each other in parallel so as to form a flow path from the scroll passage 5a of the turbine housing 5 to the discharge port 5b. Nozzle vanes 13 are attached to several circumferential locations (for example, 12 locations) of the flow path formed between the first and second nozzle plates 11 and 12 so that the posture can be changed.

  As shown in FIGS. 4 and 6, the first and second support shafts 14 and 15 are fixed to the left and right sides of the nozzle vane 13 so as to be connected in a straight line. The protruding end of the first support shaft 14 rotates in a through hole (reference numeral omitted) of the first nozzle plate 11, and the protruding end of the second support shaft 15 rotates in a through hole (reference numeral omitted) of the second nozzle plate 12. Insertion is supported as possible.

  The actuator 20 collectively changes the postures of all the nozzle vanes 13 and includes a unison ring 21, a drive source 22, a link mechanism 23, and the like.

  First, the unison ring 21 is arranged so as to be adjacent to the first impeller plate 11 in a non-contact manner closer to the compressor impeller 2. The unison ring 21 is supported by the first nozzle plate 11 so as to be rotatable in both circumferential directions. For this purpose, as shown in FIGS. 3, 5 and 7, a plurality of rollers 31 are rotatably attached to the first nozzle plate 11 via support shafts 32. Each roller 31 is inscribed in the inner peripheral surface of the unison ring 21.

  Although not shown in detail, the drive source 22 converts a direct current motor (DC motor) that generates rotational power into a linear motion for pushing and pulling the link rod 24 of the link mechanism 23. And a power conversion mechanism (for example, a gear mechanism and a worm mechanism).

  The link mechanism 23 transmits power generated by the drive source 22 to the unison ring 21 as rotational power. As shown in FIGS. 7 and 8, the link rod 24, the link arm 25, the first and second Link pins 26 and 27, an operation lever 28, a vane arm 29, and the like are provided.

  As shown in FIGS. 3, 5, and 8, grooves 21 a are provided at several locations on the inner periphery of the unison ring 21. A part of one operating lever 28 and many vane arms 29 are engaged with each groove 21a.

  The vane arms 29 are provided in the same number as the nozzle vanes 13, and the protruding ends of the first support shafts 14 are individually fixedly attached to the tilting fulcrums of the vane arms 29. When the operation lever 28 is tilted by a predetermined angle in a predetermined direction by the actuator 20, the unison ring 21 is rotated by a predetermined angle in the predetermined direction, and the vane arms 29 are collectively linked by the unison ring 21 in the predetermined direction. It can be tilted at an angle.

  One end of the second link pin 27 is fixed to the tilting fulcrum of the operation lever 28, and one end side of the link arm 25 is fixed to the other end of the second link pin 27. One end of the first link pin 26 is fixed to the other end of the link arm 25, and one end of the link rod 24 is fixed to the other end of the first link pin 26. An output member (not shown) of the power conversion mechanism of the drive source 22 is connected to the other end of the link rod 24. The second link pin 27 is inserted so as to be rotatable in a cylindrical bush 33 penetratingly attached to the flange 4 a of the bearing housing 4.

  The control unit 100 controls the actuator 20. In this embodiment, the control unit 100 is, for example, an existing engine control computer (ECU) that is essential for various operation controls of the engine 1. The control unit 100 composed of such an existing ECU is equipped with at least a function for controlling the supercharging capability of the turbocharger 1 and a function for removing deposits adhering to the movable part of the actuator 20 at an appropriate timing. Has been.

  Although not shown in detail, the control unit 100 has a known configuration including a CPU (central processing unit), a ROM (program memory), a RAM (data memory), a backup RAM (nonvolatile memory), and the like. The The ROM stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU executes arithmetic processing based on various control programs and maps stored in the ROM. The RAM is a memory that temporarily stores calculation results in the CPU, data input from each sensor, and the like. The backup RAM is a nonvolatile memory that stores data to be saved when the engine 1 is stopped. It is memory.

  By the way, some of the movable parts of the actuator 20 (the unison ring 21, the second link pin 27 of the link mechanism 23, the operation lever 28, and the vane arm 29) are annular spaces 9 provided between the bearing housing 4 and the turbine housing 5. However, the drive source 22 of the actuator 20, the link rod 24 of the link mechanism 23, the link arm 25, and the first link pin 26 are arranged so as to be exposed to the outside of the flange 4 a of the bearing housing 4. .

  Specifically, the annular space 9 will be described. A radially outward flange 4 a is provided at a position near the turbine in the axially intermediate region of the outer peripheral surface of the bearing housing 4. An outer cylinder portion 5c of the turbine housing 5 is coupled to the flange 4a. In the joint portion, the annular space 9 is formed so as to be adjacent to the scroll passage 5a.

  By the way, the inner diameter side region on the side wall near the bearing housing 4 in the turbine housing 5 is opened to form a row portion that communicates the scroll passage 5a and the annular space 9. However, the first nozzle plate 11 is attached to the communication portion so as to block the communication portion.

  A facing gap between the inner peripheral surface of the second nozzle plate 12 and the facing surface of the second nozzle plate 12 in the turbine housing 5 is sealed with a seal ring 16.

  Next, the operation of the variable nozzle unit 7 will be described.

  When the link rod 24 is pulled by the actuator 20 as shown by an arrow X1 in FIG. 3 or pushed as shown by an arrow Y1 in FIG. 5, the link arm 25 is rotated in a predetermined direction by a predetermined angle. The operation lever 28 is tilted by 25. As a result, the unison ring 21 is rotated by a predetermined angle in the clockwise direction as indicated by the arrow X2 in FIG. 3 or in the counterclockwise direction as indicated by the arrow Y2 in FIG. 5, and the vane arms 29 are tilted synchronously. . As the vane arms 29 are tilted, the nozzle vanes 13 integrated with the vane arms 29 via the first support shaft 14 are tilted in synchronization with each other. (Throat area) will be adjusted.

  Specifically, when the link rod 24 is pulled as shown by the arrow X1 in FIG. 3, the interval between the nozzle vanes 13 is maximized as shown in FIG. On the other hand, when the link rod 24 is pushed as shown by an arrow Y1 in FIG. 5, the facing interval (flow channel area or throat area) of each nozzle vane 13 is minimized as shown in FIG.

  Incidentally, if the attitude of the nozzle vane 13 is adjusted so that the facing interval (flow path area or throat area) between the adjacent nozzle vanes 13 is reduced in the low rotation range of the internal combustion engine, the flow rate of the exhaust gas increases and the low rotation speed is reduced. It becomes possible to obtain a high supercharging pressure from the region.

  By the way, the unburned gas contained in the exhaust gas flowing through the scroll passage 5a may leak into the annular space 9 from the attachment gap of the first nozzle plate 11 to the portion where the scroll passage 5a and the annular space 9 are communicated. . When such leakage is repeated, the unburned gas moves to the movable parts of the actuator 10 (the unison ring 21, the second link pin 27 of the link mechanism 23, the operation lever 28, the vane arm 29) disposed in the annular space 9. This deposit (deposit) may hinder the movement of the movable part.

  Therefore, in this embodiment, as shown in FIGS. 7 to 12, the first nozzle plate 11 is provided with a through hole 41 for allowing the exhaust gas to flow into the annular space 9 from the scroll passage 5a. The hole 41 is configured to be opened or closed by an opening / closing part 42 provided in the unison ring 21.

  When the through hole 41 is opened, a part of the high-temperature exhaust gas flowing through the scroll passage 5 a is caused to flow into the annular space 9 through the through hole 41. When the hot exhaust gas flows into the annular space 9 in this way, the heat of the hot exhaust gas causes the movable parts of the actuator 10 (the unison ring 21, the second link pin 27 of the link mechanism 23, the operation lever 28, Deposits deposited and deposited on the vane arm 29) are vaporized and lost. As a result, the movement of the movable parts of the actuator 10 can be maintained well over a long period of time, so that the reliability of the variable capacity turbocharger 1 can be increased.

  This will be specifically described below. The through hole 41 is provided so as to penetrate substantially parallel to the plate thickness direction or the central axis direction of the first nozzle plate 11. The opening / closing part 42 is attached to a location facing the through hole 41 in the unison ring 21 in the axial direction parallel to the central axis.

  The opening / closing part 42 is preferably an elastic body having at least heat resistance and corrosion resistance, and may be a leaf spring, for example. As shown in FIGS. 9 and 10, the opening / closing portion 42 made of a leaf spring is formed in a substantially trapezoidal shape when viewed from the side by bending several portions of the rectangular plate by press molding or the like. Thereby, the flat part 42a of the opening / closing part 42 is elastically pressed to the first nozzle plate 11 on the surface. Moreover, the flat portion 42 a of the opening / closing portion 42 is set such that the area of the flat portion 42 a is larger than the opening area of the through hole 41 so that the through hole 41 can be completely covered.

  As shown in FIG. 9, when the unison ring 21 is disposed at a position where the flow passage area between the nozzle vanes 13 is maximized, the opening / closing portion 42 is disposed at a position where the through hole 41 is opened. On the other hand, as shown in FIG. 10, when the unison ring 21 is disposed at a position where the flow path area is minimized, the opening / closing portion 42 is disposed at a position where the through hole 41 is closed.

  Furthermore, in this embodiment, since the operation lever 28 that directly transmits the rotational power to the unison ring 21 is disposed at a predetermined phase in the circumferential direction of the unison ring 21 at the installation location of the through hole 41, the operation lever The through hole 41 is installed at a position facing the arrangement position 28 in the axial direction. The operation lever 28 corresponds to a “final power transmission member” recited in the claims.

  Next, the opening / closing operation of the through hole 41 will be described with reference to the flowchart of FIG.

  This flowchart is executed every predetermined period (several milliseconds to several tens of milliseconds) from the start of the internal combustion engine.

  First, in step S1, the amount of deposit deposited on and depositing on the movable parts of the actuator 10 (the unison ring 21, the second link pin 27 of the link mechanism 23, the operation lever 28, and the vane arm 29) is estimated.

  In recent years, although not shown, by adding an exhaust gas purifying fuel to the upstream side of the scroll passage 5a, this fuel is combusted by an exhaust system catalyst connected to the exhaust port 5b of the turbine housing 5 and heated to a high temperature. The atmosphere is configured to enhance the exhaust gas purification ability. In such a case, a lot of unburned gas is contained in the exhaust gas discharged from the internal combustion engine to the scroll passage 5a.

  In consideration of this point, as an example of the estimation method in step S1, the movable parts (unison ring 21, link) of the actuator 10 are based on the timing and amount of the exhaust gas purification fuel added to the upstream side of the scroll passage 5a. The amount of deposit deposited on the second link pin 27, the operating lever 28, and the vane arm 29) of the mechanism 23 can be estimated. Generally, when an accelerator pedal (not shown) is turned off, the exhaust gas purification fuel is not added.

  Thereafter, in subsequent step S2, it is determined whether or not the estimated value A estimated in step S1 exceeds a predetermined threshold value X. The threshold value X is appropriately set based on results obtained by various experiments or simulations.

  Here, if A ≦ X, a negative determination is made in step S2, and this flowchart is terminated. On the other hand, if A> X, an affirmative determination is made in step S2, and the process proceeds to the subsequent step S3.

  In this step S3, the flow rate of the exhaust gas flowing through the scroll passage 5a is measured, and it is determined whether or not the measured value B exceeds a predetermined threshold value Y. The threshold value Y is appropriately set based on results obtained by various experiments or simulations.

  Here, if B ≦ Y, a negative determination is made in step S3, and step S3 is repeated until the measured value B exceeds the threshold value Y. On the other hand, if B> Y, an affirmative determination is made in step S3, and the process proceeds to the subsequent step S4.

  In this step S4, the through hole 41 is opened. Here, the actuator 10 operates the unison ring 21 in a predetermined direction in the circumferential direction (the direction of arrow 61 in FIG. 10), thereby displacing the opening / closing portion 42 in the predetermined direction in the circumferential direction integrally with the unison ring 21. The hole 41 is opened.

  In this embodiment, as shown in FIG. 12, the through hole 41 is closed in the normal rotation angle region where the unison ring 21 is used for normal control of the supercharging capability, and the rotation angle position deviated from the normal rotation angle region. The through hole 41 is fully opened at θx. Therefore, in step S4, the unison ring 21 is rotated beyond the maximum rotation angle position θmax to the rotation angle position θx.

  Thereby, a part of the exhaust gas flowing through the scroll passage 5 a flows into the annular space 9 from the through hole 41. Since the exhaust gas flowing into the annular space 9 is easy to touch the unison ring 21 and the operation lever 28 immediately after flowing in, the movable parts of the actuator 10 (the unison ring 21, the first link pin 27 of the link mechanism 23, the operation lever 28, When deposits are attached to the vane arm 29), the deposits are vaporized and lost by the high-temperature exhaust gas.

  Thereafter, in the subsequent step S5, the opening times of the through holes 41 are integrated, and it is determined whether or not the integrated value C exceeds a predetermined threshold value Z. The threshold value Z is appropriately set based on results obtained by various experiments or simulations.

  Here, if C ≦ Z, that is, if the deposit in the annular space 9 has not disappeared, a negative determination is made in step S5, and the process returns to step S3. On the other hand, if C> Z, that is, if the deposit in the annular space 9 can be eliminated, an affirmative determination is made in step S5, and the process proceeds to the subsequent step S6.

  In this step S6, the through hole 41 is closed. Here, the unison ring 21 is operated by the actuator 10 in a predetermined direction in the circumferential direction (the direction of the arrow 60 in FIG. 9). Thereafter, the flowchart is terminated.

  In this embodiment, the step S1 corresponds to “estimating means” recited in the claims, the steps S2 to S4 correspond to “first processing means” recited in the claims, and the steps S5 and S6 are claimed. This corresponds to the “second processing means” described in the section.

  As described above, in the embodiment to which the present invention is applied, the movable parts (the unison ring 21, the first link pin 27 of the link mechanism 23, the operation lever 28, and the vane arm 29) of the actuator 10 disposed in the annular space 9 are used. Since unburned gas contained in the exhaust gas may adhere and accumulate over time, the deposits (vapor deposits) are vaporized and disappeared by opening the through holes 41 at an appropriate timing.

  As a result, the movement of the movable part of the actuator 10 can be maintained satisfactorily over a long period of time, so that the reliability of the variable capacity turbocharger 1 can be increased. Further, as shown in FIG. 12, since the through hole 41 is opened in a region exceeding the normal use region, it is possible to minimize the loss of supercharging efficiency.

  In particular, in this embodiment, since the through hole 41 is provided at a position facing the operation lever 28 whose movement is easily hindered by the deposit in the axial direction, the through hole 41 flows into the annular space 9 when the through hole 41 is opened. High temperature exhaust gas can easily touch the operation lever 28 of the movable parts immediately after the inflow. For this reason, it is possible to vaporize and eliminate deposits, which are movement hindering factors accumulated on the operation lever 28, among the movable parts, with the high-temperature exhaust gas.

  In this embodiment, since the unison ring 21 is operated so as to open the through hole 41 when the accelerator pedal (not shown) is turned off, the exhaust gas purification is performed when the through hole 41 is opened. Fuel is not included in the exhaust gas. For this reason, even if exhaust gas flows into the annular space 9 from the through hole 41, it is possible to prevent excess fuel from remaining in the annular space 9. In this manner, the through hole 41 can be opened at an optimal timing.

  Furthermore, in this embodiment, since the opening / closing part 42 for opening and closing the through hole 41 is a leaf spring, when the opening 41 of the first nozzle plate 11 is closed, the opening / closing part 42 made of a leaf spring is the first. It is possible to stabilize the opening / closing operation of the through hole 41, such as avoiding the problem of being separated from the nozzle plate 11.

  In addition, this invention is not limited only to the said embodiment, It can change suitably in the range equivalent to the claim and the said range.

  (1) In the above embodiment, an example is given in which one through hole 41 is installed at a location facing the operation lever 28 in the first nozzle plate 11 in the axial direction, but the present invention is limited to this. is not. The number of the through holes 41 and the installation location of the through holes 41 may be arbitrary.

  (2) In the above embodiment, as shown in FIG. 12, an example in which the through-hole 41 is opened in the rotation angle region removed from the normal rotation angle region used for the normal control of the supercharging capacity of the unison ring 21 is given. However, the present invention is not limited to this. For example, as shown in FIG. 13, the unison ring 21 can be configured to open or close the through hole 41 in a normal rotation angle region used for normal control of the supercharging capability.

  Specifically, in the example shown in FIG. 13, all the through holes 41 are formed in the unison ring 21 from the minimum rotation angle position θmin at which the flow path area is minimum to the rotation angle position θy of about 2/3 of the normal rotation angle region. When the unison ring 21 is disposed at the rotation angle position θy of about 2/3 of the normal rotation angle region so as to be closed, the maximum rotation angle position that starts to open the through hole 41 and maximizes the channel area The through hole 41 is fully opened at a position θz slightly before θmax.

  As described above, when the through hole 41 is opened and closed in conjunction with the rotation operation in the normal control of the supercharging capability of the unison ring 21, a control system dedicated to opening and closing the through hole 41 is provided as in the above embodiment. It is not necessary to equip, and it becomes possible to suppress an increase in equipment cost.

  Moreover, even if the unison ring 21 is disposed at the rotation angle position θmax that maximizes the flow path area, the exhaust that flows into the annular space 9 from the scroll passage 5a through the through hole 41 even if the through hole 41 is fully opened. Since the amount of gas is small from the total flow rate of the exhaust gas flowing through the scroll passage 5a, it is possible to minimize the loss of supercharging capability.

  The present invention can be suitably applied to a variable capacity turbocharger including a variable nozzle unit for enabling the capacity of exhaust gas discharged from a scroll passage of a turbine housing to an exhaust port through a turbine wheel to be changed. .

1 Turbocharger
2 Turbine wheel
2a Turbine shaft
3 Compressor impeller
4 Bearing housing
4a Flange of bearing housing
5 Turbine housing
5a Scroll passage of turbine housing
5b Turbine housing outlet
7 Variable nozzle unit
9 annular space 11 first nozzle plate 11a through hole 12 second nozzle plate 13 nozzle vane 20 actuator 21 unison ring 22 drive source 23 link mechanism 24 link rod 25 link arm 26 first link pin 27 second link pin 28 operation lever 29 vane arm 41 through hole 42 opening / closing part 100 control part

Claims (8)

A variable nozzle unit for changing the capacity of exhaust gas exhausted from the scroll passage of the turbine housing to the exhaust port through the turbine wheel,
The variable nozzle unit is provided at first and second nozzle plates opposed to each other so as to form a flow path from the scroll passage to the discharge port, and at several circumferential positions between the first and second nozzle plates. A nozzle vane, and an actuator for changing the area of the flow path by changing the posture of all the nozzle vanes at once,
In an area adjacent to the scroll passage, an annular space for disposing a part of a movable part for power transmission provided in the actuator is provided in a state communicating with the scroll passage.
The first nozzle plate is attached to the communication part so as to close the communication part,
The first nozzle plate is provided with a through hole for allowing inflow of exhaust gas from the scroll passage to the annular space,
A variable capacity turbocharger, wherein an opening / closing part for opening or closing the through hole is provided in a part of the movable part. The variable capacity turbocharger according to claim 1, wherein
The opening / closing part opens the through hole when the movable part is disposed at a position that maximizes the flow path area, while the movable part is disposed at a position that minimizes the flow path area. A variable capacity turbocharger, wherein the variable capacity turbocharger is provided in the movable part so as to sometimes close the through hole. The variable capacity turbocharger according to claim 1 or 2,
The actuator includes a unison ring composed of an annular plate that is arranged in a state of being rotatably supported at a position adjacent to the first nozzle plate and in which the nozzle vane is tiltably supported at several circumferential positions. A drive source that generates power necessary to rotate the ring from a position that maximizes the flow path area to a position that minimizes the flow path area, and the power generated by the drive source is rotated to the unison ring. And a final power transmission member that directly transmits the rotational power to the movable part in the link mechanism at a predetermined phase in the circumferential direction of the movable part comprising the annular plate. Has been placed,
The variable capacity turbocharger is characterized in that the through hole is installed corresponding to an arrangement position of the final power transmission member, and the unison ring and the final power transmission member are the movable parts. The variable capacity turbocharger according to any one of claims 1 to 3,
The variable nozzle unit further includes a control unit that controls the actuator,
The control unit is configured to estimate an accumulation amount of deposit that adheres to and accumulates on the movable part based on a timing and an amount of the exhaust gas purification fuel added to the upstream side of the scroll passage;
After determining that the estimated value by the estimating means has exceeded a predetermined value, when it is determined that the flow rate of the exhaust gas flowing through the scroll passage has exceeded a predetermined value, the movable part is configured to open the through hole with the actuator. And a first processing means for operating the variable capacity turbocharger. The variable capacity turbocharger according to any one of claims 1 to 3,
The variable nozzle unit further includes a control unit that controls the actuator,
The control unit is configured to estimate an accumulation amount of deposit that adheres to and accumulates on the movable part based on a timing and an amount of the exhaust gas purification fuel added to the upstream side of the scroll passage;
After determining that the estimated value by the estimating means exceeds a predetermined value, it is determined that the accelerator pedal is turned off so that the exhaust gas purification fuel is not added, and the flow rate of the exhaust gas flowing through the scroll passage is a predetermined value. And a first processing means for operating the movable part so as to open the through-hole with the actuator when it is determined that the pressure exceeds the variable capacity turbocharger. The variable capacity turbocharger according to claim 4 or 5,
The control unit integrates the opening time of the through hole, and when it is determined that the integrated value exceeds a predetermined value, a second processing unit that operates the movable part to close the through hole with the actuator. A variable capacity turbocharger characterized by further comprising: The variable capacity turbocharger according to any one of claims 1 to 6,
A bearing housing for rotatably supporting a common rotating shaft that integrally rotates the turbine wheel and the compressor impeller;
The turbine housing is coupled to a radially outward flange provided near the turbine in an axially intermediate region of the outer periphery of the bearing housing;
The variable capacity turbocharger, wherein the annular space is provided at a joint portion between a flange of the bearing housing and the turbine housing. In the variable capacity turbocharger according to any one of claims 1 to 7,
The variable capacity turbocharger, wherein the opening / closing portion is a leaf spring fixed to the movable part and elastically pressed against the first nozzle plate.

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