JP2007192123A - Turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress excessive increase of pressure near a nozzle while a flow rate of exhaust flowing from the nozzle to a flow passage between blades of a turbine wheel is accurately adjusted to be an optimum value, so as to suppress deterioration in supercharging efficiency of a turbocharger. <P>SOLUTION: A slider 27 having fixed blades 25 for middle and high speeds is displaced in an axial direction of a rotor shaft 13 when exhaust from a second nozzle 23 flows in the flow passage 16 between blades of a turbine wheel 14 of a turbocharger 11, so that a gas flowing area of the nozzle 23 is changed. The displacement of the slider 27 is performed between a projecting position where the fixed blades 25 for middle and high speeds is abutted on a nozzle wall face 23a, and a retreating position where the fixed blades 25 for middle and high speeds is in a state farthest away from the nozzle wall face 23a. When the slider 27 is displaced to the projecting position, there is no clearance generated between the fixed blades 25 for middle and high speeds and the nozzle wall face 23a. When an exhaust temperature of an internal combustion engine becomes high, the fixed blades 25 for middle and high speeds is not stuck to the nozzle wall face 23a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a turbocharger used for supercharging an internal combustion engine.

  2. Description of the Related Art Conventionally, internal combustion engines for automobiles and the like are known in which a turbocharger is provided as a supercharger in order to improve output. Such a turbocharger includes a turbine scroll into which exhaust gas from an internal combustion engine is sent, a nozzle for flowing the exhaust gas in the turbine scroll through a passage between blades of the turbine wheel, and a compressor wheel that rotates integrally with the turbine wheel. Then, when the wheel rotates due to the inflow of exhaust gas from the nozzle into the inter-blade flow path of the turbine wheel, the compressor wheel rotates accordingly and air is forcibly sent toward the combustion chamber of the internal combustion engine.

  By the way, when the internal combustion engine is running at a low speed, the exhaust flow rate of the engine is reduced, so that the flow rate of the exhaust gas flowing from the nozzle into the flow path between the blades of the turbine wheel decreases. Thus, when the flow velocity of the exhaust gas flowing into the inter-blade flow path of the turbine wheel decreases, the turbine wheel cannot be effectively rotated, and accordingly, the internal combustion engine can be effectively supercharged by the rotation of the compressor wheel. Disappear. In order to deal with these problems, when the internal combustion engine is running at a low speed where the exhaust flow rate is low, the flow rate of the exhaust gas flowing into the inter-blade passage of the turbine wheel is sufficiently high to effectively rotate the wheel. It is also conceivable to set the gas flow area of the nozzle small. However, when the gas flow area of the nozzle is set to be small as described above, the pressure in the vicinity of the nozzle becomes excessively high at the time of medium-high rotation of the internal combustion engine where the exhaust flow rate increases.

  Therefore, as shown in Patent Document 1, a nozzle with blades and a nozzle without blades are provided as the nozzle, and the gas flow area of the nozzle with blades is set to a value suitable for low rotation of the internal combustion engine. It has been proposed to provide a control valve that opens and closes in order to inhibit and permit the inflow of exhaust gas to the inter-blade flow path of the turbine wheel through it. In this case, when the internal combustion engine is running at a low speed, the control valve is closed and the inflow of exhaust gas to the inter-blade passage of the turbine wheel through the vaneless nozzle is prohibited. The inflow is performed only from the bladed nozzle. Therefore, when the internal combustion engine has a low rotational speed at which the exhaust gas flow rate is low, the flow velocity of the exhaust gas flowing into the inter-blade flow path of the turbine wheel can be sufficiently increased to effectively rotate the wheel. On the other hand, at the time of high rotation of the internal combustion engine, the control valve is opened to allow the inflow of exhaust gas to the inter-blade channel through the bladeless nozzle. For this reason, it is possible to suppress the pressure in the vicinity of the bladed nozzle from becoming excessively high during the high rotation of the internal combustion engine in which the exhaust gas flow rate increases.

  If the turbocharger of the above-mentioned patent document 1 is used, the flow rate of the exhaust gas flowing into the inter-blade passage of the turbine wheel when the internal combustion engine is rotating at a low speed and the suppression of the excessive pressure rise near the nozzle when the internal combustion engine is rotating at a high speed It becomes possible to improve the efficiency of supercharging by the turbocharger by achieving both. However, when the internal combustion engine is running at medium speed, the exhaust flow rate of the engine is about halfway between the low speed and the high speed, so the control valve is controlled to be either in the open state or the closed state. However, it is difficult to suppress the pressure in the vicinity of the nozzle from becoming too high while setting the flow velocity of the exhaust gas flowing into the inter-blade flow path of the turbine wheel to a value that effectively rotates the wheel. That is, when the control valve is opened during the middle rotation of the internal combustion engine, it is possible to suppress an excessive increase in pressure near the nozzle, but the flow velocity of the exhaust gas flowing into the inter-blade passage of the turbine wheel is the same as that of the wheel. Is less than the value that effectively rotates. Further, when the control valve is closed during the internal rotation of the internal combustion engine, the flow velocity of the exhaust gas flowing into the inter-blade passage of the turbine wheel can be increased to a suitable value, but the pressure near the nozzle is increased. It is inevitable that the supercharging efficiency will decrease due to excessive increase.

  In order to deal with these problems, instead of adopting the above-described configurations such as the nozzle with blades, the nozzle without blades, and the control valve, the nozzle may be provided with variable blades that open and close to make the gas flow area of the nozzle variable. Conceivable. A plurality of the variable blades are provided at predetermined intervals between the nozzle wall surfaces facing each other in the nozzle, and are opened and closed in synchronization with each other in a rotation direction around an axis orthogonal to the nozzle wall surfaces. Based on the opening / closing operation of the adjacent variable blades, the size of the gap between the movable blades, in other words, the gas flow area of the nozzle changes.

As described above, in a turbocharger in which variable vanes are provided in a nozzle, the flow velocity of the exhaust gas flowing through the nozzles to the inter-blade flow path is changed by opening and closing the variable vanes and changing the gas flow area of the nozzles. It can be variable. Therefore, when the internal combustion engine rotates at a low speed, the movable blade is displaced to the closed side, and as the rotational speed of the internal combustion engine increases, the variable blade is displaced to the open side to increase the gas flow area of the nozzle, It is considered that the following effects can be obtained. In other words, while adjusting the flow rate of the exhaust gas flowing into the inter-blade flow path to an optimal value at low engine speed, the pressure near the nozzle is adjusted to an optimal value at the exhaust gas flow rate from engine rotation to high rotation. It is considered possible to suppress a decrease in supercharging efficiency due to excessive increase.
JP-A-60-166718

  However, in a turbocharger in which variable vanes are provided on the nozzle, it is unavoidable that the exhaust leaks from the clearance between the nozzle wall surface and the variable vanes, and the exhaust flowing from the nozzle to the flow path between the blades of the turbine wheel by the amount of the exhaust leak. The flow rate of Therefore, it becomes difficult to adjust the flow velocity of the exhaust gas flowing from the nozzle to the flow path between the blades of the turbine wheel to a value that can efficiently rotate the turbine wheel, and the turbocharger's supercharging efficiency is lowered.

  Further, when the exhaust temperature of the internal combustion engine becomes high, for example, 950 ° C. or higher, the nozzle that opens and closes between the nozzle wall surfaces facing the nozzles is fixed to the nozzle wall surface, and the gas flow area of the nozzle cannot be changed. . As a result, it becomes impossible to adjust the flow rate of the exhaust gas flowing from the nozzle to the flow path between the blades of the turbine wheel to a value that can efficiently rotate the turbine wheel, or the pressure near the nozzle may increase excessively. As a result, the turbocharging efficiency of the turbocharger decreases.

  The present invention has been made in view of such circumstances, and its purpose is to accurately adjust the flow velocity of the exhaust gas flowing from the nozzle to the inter-blade flow path of the turbine wheel to an optimum value, in the vicinity of the nozzle. An object of the present invention is to provide a turbocharger that can suppress an excessive increase in the pressure of the engine and suppress a decrease in turbocharging efficiency of the turbocharger.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, the invention according to claim 1 includes a turbine scroll into which exhaust gas from the internal combustion engine is fed, and a nozzle that causes the exhaust gas in the turbine scroll to flow into the inter-blade passage of the turbine wheel. In the turbocharger in which the wheel rotates by inflow of exhaust gas into the inter-blade passage of the turbine wheel, a protruding position that protrudes from one nozzle wall surface side to the other nozzle wall surface among the opposed nozzle wall surfaces in the nozzle And a slider that is displaced between an immersion position that is farthest from the other nozzle wall surface, and a portion that is located in the nozzle in the slider when the slider is in the protruding position. And a fixed wing for defining a gas flow area of the nozzle.

  According to the above configuration, when the slider is displaced to the protruding position, the gas flow area of the nozzle becomes a value determined by the fixed blade formed on the slider. As the slider is displaced from the protruding position toward the immersive position, the stationary blade formed on the slider moves away from the other nozzle wall surface, and the gas flow area of the nozzle increases. Therefore, the flow rate of the exhaust gas flowing from the nozzle to the inter-blade passage of the turbine wheel is adjusted by changing the gas flow area of the nozzle by displacing the slider between the protruding position and the immersion position. When adjusting the flow velocity of the exhaust gas flowing into the inter-blade flow path by changing the gas flow area of the nozzle by moving the fixed blade closer to or away from the other nozzle wall surface as described above, the following effects are obtained. Can be obtained. That is, due to exhaust leakage from the clearance between the nozzle wall surface and the variable blade, as in the case of adjusting the flow velocity of the exhaust flowing into the inter-blade flow path by opening and closing the variable blade provided in the nozzle, It is not difficult to adjust the flow rate of the exhaust gas to an appropriate value, and the adjustment can be performed accurately. In addition, when the exhaust temperature of the internal combustion engine becomes high, the variable blade does not adhere to the nozzle wall surface as in the case where the variable blade is adopted, and the exhaust flow velocity cannot be adjusted to an appropriate value. It is possible to avoid an excessive increase in pressure near the nozzle. Therefore, the flow rate of the exhaust gas flowing from the nozzle to the flow path between the blades of the turbine wheel is accurately adjusted to an optimum value for effectively rotating the turbine wheel, and an excessive increase in pressure near the nozzle is suppressed. Therefore, it is possible to suppress a decrease in turbocharger efficiency due to the inability to perform them.

  According to a second aspect of the present invention, the gist of the first aspect of the present invention is that the slider is provided so that the fixed blade is positioned immediately before the inter-blade passage of the turbine wheel.

  The farther the fixed blade is located upstream of the inter-blade flow path of the turbine wheel, the more difficult it is to determine the flow velocity of the exhaust gas flowing from the nozzle to the inter-blade flow path by the fixed blade. According to the above configuration, since the fixed blade is positioned immediately before the inter-blade channel, the flow velocity of the exhaust gas flowing from the nozzle into the inter-blade channel can be accurately determined by the fixed blade.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a first nozzle and a second nozzle are provided as the nozzles, and the first nozzle is fixed to a nozzle wall surface and gas from the same nozzle. A low speed fixed blade is provided for setting the flow area to a value suitable for low rotation of the internal combustion engine, and the internal combustion engine is fully closed to prohibit the inflow of exhaust gas to the second nozzle during low rotation of the internal combustion engine. A control valve is provided that is fully opened to allow inflow of exhaust gas to the second nozzle during middle and high rotations, and the slider is displaced between a projecting position and an immersion position in the second nozzle. The fixed blade formed on the slider is a medium-high speed fixed blade that sets the gas flow area of the second nozzle to a value suitable for the middle rotation of the internal combustion engine when the slider is displaced to the protruding position. The It was a fact.

  According to the above configuration, the control valve is closed during low rotation of the internal combustion engine, the inflow of exhaust gas to the second nozzle is prohibited, and the inflow of exhaust gas to the inter-blade passage of the turbine wheel is limited to the first nozzle. Is done from. With respect to the first nozzle, the low speed fixed blade is fixed to the nozzle wall surface, and the gas flow area of the nozzle is fixed to a value suitable for the low speed rotation of the internal combustion engine by the low speed fixed blade. There is no clearance between the fixed blade for low speed and the nozzle wall surface of the first nozzle, and the flow velocity of the exhaust gas flowing from the first nozzle to the inter-blade passage of the turbine wheel is appropriately affected by the exhaust leakage from the clearance. It does not become difficult to adjust to a correct value. Therefore, it is possible to accurately adjust the flow rate of the exhaust gas flowing from the first nozzle into the inter-blade passage of the turbine wheel when the internal combustion engine rotates at a low speed to a value suitable for effectively rotating the turbine wheel.

Further, the control valve is opened during middle and high speed rotation of the internal combustion engine, and exhaust flows into the inter-blade passage of the turbine wheel from both the first nozzle and the second nozzle.
By holding the slider in the protruding position during the middle rotation of the internal combustion engine, the fixed blade for medium and high speed formed on the slider comes into contact with the other nozzle wall surface of the second nozzle, and the fixed blade for medium and high speed The gas flow area of the second nozzle can be set to a value suitable for medium rotation of the internal combustion engine. In other words, the flow velocity of the exhaust gas flowing from the second nozzle into the flow path between the blades of the turbine wheel is effectively rotated during the middle rotation of the internal combustion engine, and the pressure near the second nozzle is not excessively increased. The value can be determined. At this time, there is no clearance between the medium- and high-speed fixed blades and the other nozzle wall surfaces, and therefore the second nozzle flows into the inter-blade channel due to exhaust leakage from the clearance. It is not difficult to adjust the exhaust flow rate to an appropriate value.

  From the middle rotation to the rotation of the internal combustion engine, the medium-to-high speed fixed blade formed on the slider moves away from the other nozzle wall surfaces by changing the slider from the protruding position to the immersed position as the rotational speed of the engine increases. The gas distribution area of the nozzle will increase. By changing the gas flow area of the second nozzle in this way, the flow velocity of the exhaust gas flowing from the second nozzle to the inter-blade passage of the turbine wheel can be adjusted to an appropriate value, and the vicinity of the second nozzle can be adjusted. An excessive increase in pressure can be suppressed. Further, as described above, when the gas flow area of the second nozzle is changed by moving the stationary blade for medium and high speed closer to or away from the other nozzle wall surface, even if the exhaust temperature of the internal combustion engine becomes higher, the other This prevents the middle and high speed fixed blades from adhering to the nozzle wall, thereby preventing the exhaust flow velocity from being adjusted to an appropriate value or causing an excessive increase in pressure near the second nozzle. be able to.

  As described above, while accurately adjusting the flow rate of the exhaust gas flowing into the inter-blade flow path of the turbine wheel from low to high rotation of the internal combustion engine to an optimum value for effectively rotating the turbine wheel, It is possible to suppress an excessive increase in pressure in the vicinity of the nozzle, and it is possible to suppress a decrease in turbocharging efficiency of the turbocharger due to the inability to perform them.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
FIG. 1 is a cross-sectional view showing a portion of an exhaust system side of a turbocharger 11 for supercharging an internal combustion engine mounted on an automobile.

  As shown in the figure, the turbocharger 11 includes a rotor shaft 13 that is rotatably supported by a center housing 12. A turbine wheel 14 is attached to one end portion (right end portion in the figure) of the rotor shaft 13. The turbine wheel 14 is provided with a plurality of blades 15 along a circumferential direction centering on the axis of the rotor shaft 13, and a space 16 between the blades 15 is an inter-blade flow path 16.

  A turbine scroll 17 is attached to one end side of the center housing 12 so as to surround the outer periphery of the turbine wheel 14 and extend in a spiral shape. The inside of the turbine scroll 17 communicates with an exhaust passage 21 of the internal combustion engine, and exhaust gas of the internal combustion engine is sent from the exhaust passage 21. The exhaust gas fed into the turbine scroll 17 is caused to flow through the inter-blade channel 16 of the turbine wheel 14 so that the turbine wheel 14 and the rotor shaft 13 are rotated. When the rotor shaft 13 rotates, the compressor wheel attached to the other end of the shaft 13 also rotates, and accordingly, the air in the intake passage of the internal combustion engine is forcibly sent toward the combustion chamber.

Next, the internal structure of the turbine scroll 17 will be described in detail.
In the turbine scroll 17, a scroll passage 19 connected to the exhaust passage 21 of the internal combustion engine is formed, and a first nozzle 22 and a second nozzle that flow exhaust gas in the scroll passage 19 to the inter-blade passage 16 of the turbine wheel 14. 23 is provided. A control valve 26 driven by an actuator 26 a is provided at a connection portion between the second nozzle 23 and the scroll passage 19. The control valve 26 opens and closes between a fully closed state and a fully open state to prohibit / permit the inflow of exhaust gas from the scroll passage 19 to the second nozzle 23 through driving by the actuator 26a.

  A low-speed stationary blade 24 for setting the gas flow area of the first nozzle 22 is fixed to a portion of the turbine wheel 14 near the inter-blade channel 16 on the nozzle wall surface facing the first nozzle 22. A plurality of the low speed fixed blades 24 are provided around the turbine wheel 14 at equal intervals along the circumferential direction as shown in FIG. The gas flow area of the first nozzle 22 flows from the scroll passage 19 into the inter-blade passage 16 of the turbine wheel 14 from the scroll passage 19 through the first nozzle 22 when the internal combustion engine rotates at low speed. The exhaust gas flow rate is set to a value capable of effectively rotating the wheel 14.

  In the turbine scroll 17 shown in FIG. 1, a cylindrical slider 27 extending in the axial direction of the rotor shaft 13 (left and right in the figure) is provided at a portion corresponding to the second nozzle 23 so as to be displaceable in the axial direction. ing. Such displacement of the slider 27 is performed by driving the actuator 27a, and a groove 32 for receiving the driving force in the axial direction by the actuator 27a is formed on the outer peripheral surface of the slider 27. The slider 27 is driven by the actuator 27a from the protruding position where the nozzle wall surface 23b of the second nozzle 23 faces the other nozzle wall surface 23a and the other nozzle wall surface 23a. It is displaced between the most distant position and the immersing position where the nozzle wall surface 23b is immersed.

  When the slider 27 is in the protruding position, that is, in the position shown in FIG. 1, a portion located in the second nozzle 23 of the slider 27 has a medium / high speed for determining the gas flow area of the second nozzle 23. A fixed blade 25 is formed. A plurality of the medium- and high-speed stationary blades 25 formed on the slider 27 are provided around the turbine wheel 14 at equal intervals along the circumferential direction as shown in FIG. And the gas distribution area of the 2nd nozzle 23 is set as follows by each said fixed blade 25 for medium and high speeds. That is, the flow rate of the exhaust gas flowing into the inter-blade passage 16 of the turbine wheel 14 from the scroll passage 19 through the second nozzle 23 during the middle rotation of the internal combustion engine becomes a value capable of effectively rotating the wheel 14. In addition, the pressure in the vicinity of the second nozzle 23 is set to a value that does not increase excessively.

  The slider 27 is provided so that the medium-to-high speed fixed blade 25 is located as close as possible to the inter-blade passage 16 of the turbine wheel 14 and is located immediately before the inter-blade passage 16. . This is because the intermediate / high speed fixed vane 25 moves from the second nozzle 23 to the inter-blade channel 16 as the intermediate / high speed fixed vane 25 is positioned more upstream from the inter-blade channel 16 of the turbine wheel 14. This is because it becomes difficult to determine the flow velocity of the flowing exhaust gas.

  By the way, the supercharging efficiency of the turbocharger 11 is greatly influenced by the inflow mode of the exhaust gas into the inter-blade channel 16 such as the flow velocity when the exhaust gas flows into the inter-blade channel 16 of the turbine wheel 14. Further, the inflow mode of exhaust into the inter-blade channel 16 of the turbine wheel 14 includes the opening / closing operation of the control valve 26 and the displacement of the slider 27 in the axial direction of the rotor shaft 13, that is, the protruding position (FIG. 1) and the immersion It is made variable through displacement between the positions (FIG. 4). Therefore, in order to effectively perform the supercharging by the turbocharger 11, the control valve 26 and the slider 27 are controlled so that the exhaust flow into the inter-blade channel 16 is suitable for the operating state of the internal combustion engine. It becomes necessary to do.

  In this embodiment, such control of the control valve 26 and the slider 27 is performed through an electronic control unit 29 that performs various controls of the internal combustion engine mounted on the automobile. The electronic control unit 29 receives detection signals from various sensors such as a rotational speed sensor 28 that detects the rotational speed of the internal combustion engine, and opens and closes the control valve 26 and the slider 27 based on the engine operating state grasped from these detection signals. The actuators 26a and 27a are controlled for displacement in the axial direction. Through such control of the control valve 26 and the slider 27, the inflow mode of the exhaust gas into the inter-blade channel 16 of the turbine wheel 14 is a mode suitable for realizing effective supercharging by the turbocharger 11.

Next, the control of the control valve 26 and the slider 27 will be described in detail.
When the internal combustion engine rotates at a low speed, the control valve 26 is fully closed, and the inflow of exhaust gas from the second nozzle 23 to the inter-blade passage 16 of the turbine wheel 14 is prohibited. At this time, the inflow of exhaust gas into the inter-blade channel 16 is performed only from the first nozzle 22. With respect to the first nozzle 22, the low speed stationary blade 24 is fixed to the nozzle wall surface facing the nozzle 22, and the gas flow area of the nozzle 22 is suitable for the low speed rotation of the internal combustion engine by the low speed stationary blade 24. It is set to be the same value. There is no clearance between the low-speed stationary blade 24 and the nozzle wall surface of the first nozzle 22, and flows from the first nozzle 22 to the inter-blade channel 16 of the turbine wheel 14 under the influence of exhaust leakage from the clearance. It is not difficult to adjust the exhaust flow rate to an appropriate value. Accordingly, the flow rate of the exhaust gas flowing from the first nozzle 22 to the inter-blade passage 16 of the turbine wheel 14 when the internal combustion engine rotates at a low speed can be adjusted to a value suitable for effectively rotating the turbine wheel 14.

  Further, the control valve 26 is fully opened when the internal combustion engine rotates at a medium to high speed, and exhaust flows into the inter-blade passage 16 of the turbine wheel 14 from both the first nozzle 22 and the second nozzle 23.

  By holding the slider 27 in the protruding position, that is, in the position shown in FIG. 1 during the internal rotation of the internal combustion engine, the medium and high speed fixed blades 25 formed on the slider 27 come into contact with the nozzle wall surface 23 a of the second nozzle 23. The gas flow area of the second nozzle 23 is set to a value suitable for the middle rotation of the internal combustion engine by the medium and high speed fixed blades 25. In other words, the flow velocity of the exhaust gas flowing from the second nozzle 23 into the inter-blade passage 16 of the turbine wheel 14 is adjusted so that the turbine wheel 14 is effectively rotated during the middle rotation of the internal combustion engine while the pressure near the second nozzle 23 is increased. It is determined to be a value that does not increase. At this time, there is no clearance between the medium- and high-speed stationary blades 25 and the nozzle wall surface 23a, so that the air flows into the inter-blade channel 16 from the second nozzle 23 due to exhaust leakage from the clearance. It is not difficult to adjust the flow rate of exhaust gas to an appropriate value.

  By changing the slider 27 from the projecting position as shown in FIG. 1 to the immersive position as shown in FIG. The medium / high speed fixed blade 25 formed on the nozzle 27 moves away from the nozzle wall surface 23a, and the gas flow area of the second nozzle 23 increases. By changing the gas flow area of the second nozzle 23 in this way, the flow rate of the exhaust gas flowing from the second nozzle 23 to the inter-blade channel 16 of the turbine wheel 14 can be adjusted to an appropriate value, and the second An excessive increase in pressure in the vicinity of the nozzle 23 can be suppressed. Further, when the gas flow area of the second nozzle 23 is changed by moving the stationary blade 25 for medium and high speed close to or away from the nozzle wall surface 23a, the fixed blade is placed on the nozzle wall surface 23a even if the exhaust temperature becomes high. Therefore, it is possible to prevent the exhaust gas flow rate from being adjusted to an appropriate value and the pressure in the vicinity of the nozzle from being excessively increased.

According to the embodiment described in detail above, the following effects can be obtained.
(1) During low rotation of the internal combustion engine, exhaust flows into the inter-blade passage 16 of the turbine wheel 14 from only the first nozzle 22. There is no clearance between the nozzle wall surface of the first nozzle 22 and the low speed fixed blade 24, and the flow between the blades of the turbine wheel 14 from the first nozzle 22 is affected by exhaust leakage from the clearance. It is not difficult to adjust the flow rate of the exhaust gas flowing through the passage 16 to an appropriate value. Therefore, when the internal combustion engine is rotating at a low speed, the flow rate of the exhaust gas flowing from the first nozzle 22 into the inter-blade channel 16 can be adjusted to a value suitable for effectively rotating the turbine wheel 14.

  (2) During the middle rotation of the internal combustion engine, exhaust flows from the second nozzle 23 into the inter-blade passage 16 of the turbine wheel 14 and the slider 27 is held at the protruding position. As a result, an excessive increase in pressure in the vicinity of the second nozzle 23 can be suppressed while setting the flow velocity of the exhaust gas flowing into the inter-blade channel 16 to an optimum value during the middle rotation of the internal combustion engine. Further, at this time, there is no clearance between the medium / high speed fixed blade 25 and the nozzle wall surface 23a, so that the air flows into the inter-blade channel 16 from the second nozzle 23 due to exhaust leakage from the clearance. It is not difficult to adjust the flow rate of exhaust gas to an appropriate value.

  (3) From the middle rotation to the high rotation of the internal combustion engine, exhaust flows into the inter-blade channel 16 from the second nozzle 23, and the slider 27 moves from the protruding position to the immersive position as the engine rotational speed increases. And displaced. As a result, an excessive increase in pressure in the vicinity of the second nozzle 23 is achieved while setting the flow velocity of the exhaust gas flowing from the second nozzle 23 to the inter-blade passage 16 of the turbine wheel 14 from the middle rotation to the high rotation of the internal combustion engine. Can be suppressed. Further, when the gas flow area of the second nozzle 23 is changed as described above, even if the exhaust gas temperature becomes high, the medium-to-high speed fixed vane 25 does not adhere to the nozzle wall surface 23a, and thereby the flow velocity of the exhaust gas. Can be prevented from being adjusted to an appropriate value or the pressure in the vicinity of the nozzle is excessively increased.

  (4) By the above (1) to (3), the turbine wheel 14 is effectively rotated with the flow velocity of the exhaust gas flowing into the inter-blade passage 16 of the turbine wheel 14 from low to high rotation of the internal combustion engine. It is possible to suppress an excessive increase in pressure near the nozzle while accurately adjusting to an optimum value. And the supercharging efficiency fall of the turbocharger 11 by not being able to perform them can be suppressed.

  (5) The medium-to-high speed fixed vane 25 is located on the upstream side of the inter-blade flow path 16 of the turbine wheel 14 from the second nozzle 23 by the medium-to-high speed fixed vane 25 so that the vane It becomes difficult to determine the flow rate of the exhaust gas flowing in the inter-channel 16. However, the slider 27 on which the medium / high speed fixed blade 25 is formed is provided so that the medium / high speed fixed blade 25 is positioned immediately before the inter-blade channel 16. For this reason, the flow velocity of the exhaust gas flowing into the inter-blade channel 16 from the second nozzle 23 can be accurately determined by the fixed blade 25 for medium and high speed.

  (6) If the gas flow area of the second nozzle 23 is made variable by the opening and closing operation of the variable blade, a plurality of variable blades are provided at predetermined intervals along the circumferential direction of the turbine wheel 14, and these variable It is necessary to open and close the blades in a synchronized state using a link mechanism or the like. For this reason, it is inevitable that the structure of the turbocharger 11 becomes complicated as much as the link mechanism and the like must be provided. However, when the gas flow area of the second nozzle 23 is changed by the displacement of the slider 27 on which the medium and high speed fixed blades 25 are formed, it is not necessary to provide the link mechanism or the like. The gas flow area of the second nozzle 23 can be varied without complicating the process.

In addition, the said embodiment can also be changed as follows, for example.
The slider 27 may be provided so that the medium-to-high speed fixed blade 25 is positioned upstream from immediately before the inter-blade channel 16.

  The present invention may be applied to a turbocharger that flows exhaust gas from the scroll passage 19 into the inter-blade channel 16 through one nozzle. In this case, the gas flow area of the nozzle is changed by displacing the slider 27 in the axial direction of the rotor shaft. However, the fixed vanes formed on the slider 27 are suitable for low-speed operation of the internal combustion engine. For example, it is preferable to change to the same shape as that of the fixed blade 24 for low speed.

  The inside of the turbine scroll may be divided into two scroll passages by a partition wall, and one scroll passage may be connected to the first nozzle 22 and the other scroll passage may be connected to the second nozzle 23. In this case, the control valve 26 is provided at a connection portion between the scroll passage connected to the second nozzle 23 and the exhaust passage 21.

FIG. 3 is a cross-sectional view showing a portion on the exhaust system side of the internal combustion engine in the turbocharger of the present embodiment. Sectional drawing which shows the structure around the 1st nozzle in the turbine scroll inside the said turbocharger. Sectional drawing which shows the structure around the 2nd nozzle in the turbine scroll inside the said turbocharger. The expanded sectional view which shows the state which has a slider in an immersion position.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Turbocharger, 12 ... Center housing, 13 ... Rotor shaft, 14 ... Turbine wheel, 15 ... Blade, 16 ... Flow path between blades, 17 ... Turbine scroll, 19 ... Scroll passage, 21 ... Exhaust passage, 22 ... First Nozzle, 23 ... second nozzle, 23a, 23b ... nozzle wall surface, 24 ... low speed fixed blade, 25 ... medium and high speed fixed blade, 26 ... control valve, 26a ... actuator, 27 ... slider, 27a ... actuator, 28 ... rotation Speed sensor, 29 ... electronic control device, 32 ... groove.

Claims (3)

A turbine scroll into which the exhaust gas of the internal combustion engine is sent, and a nozzle that causes the exhaust gas in the turbine scroll to flow into the inter-blade passage of the turbine wheel. In the turbocharger where the wheel rotates,
A slider that displaces between a protruding position that protrudes from one nozzle wall surface side to the other nozzle wall surface, and an immersion position that is farthest from the other nozzle wall surface, of the nozzle wall surfaces facing each other in the nozzle. When,
A fixed vane that is formed in a portion of the slider located in the nozzle when the slider is in the protruding position and defines a gas flow area of the nozzle;
A turbocharger comprising: The turbocharger according to claim 1, wherein the slider is provided so that the fixed blade is positioned immediately before a flow path between blades of the turbine wheel. A first nozzle and a second nozzle are provided as the nozzles,
The first nozzle is provided with a low-speed stationary blade that is fixed to the nozzle wall surface and sets the gas flow area of the nozzle to a value suitable for low-speed operation of the internal combustion engine,
Control that is fully closed to prohibit the inflow of exhaust gas to the second nozzle when the internal combustion engine is running at a low speed, and is fully opened to permit the inflow of exhaust gas to the second nozzle when the internal combustion engine is running at a medium or high speed. A valve is provided,
The slider is displaced between a protruding position and an immersion position in the second nozzle,
The fixed blade formed on the slider is a medium-high speed fixed blade that sets a gas flow area of the second nozzle to a value suitable for a middle rotation of the internal combustion engine when the slider is displaced to a protruding position. The turbocharger according to 1 or 2.

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