JP4708300B2 - Turbocharger - Google Patents

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 that is provided around the turbine wheel and into which the exhaust of the internal combustion engine is sent, a nozzle that flows the exhaust in the turbine scroll to a passage between blades of the turbine wheel, and a compressor that rotates integrally with the turbine wheel. With wheels. 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.

  Patent Document 1 further includes a first nozzle that guides exhaust in the turbine scroll to the inlet of the inter-blade channel and a second nozzle that guides the exhaust to the middle of the inter-blade channel as the nozzle. There has been proposed a turbocharger that prohibits / permits the inflow of exhaust gas to the inter-blade passage through the second nozzle based on the opening / closing operation of a control valve provided upstream of the nozzle. Note that the gas flow area of the first nozzle is suitable for increasing the flow rate of the exhaust gas flowing from the nozzle to the inter-blade passage when the internal combustion engine rotates at a low speed to a value necessary for effectively rotating the turbine wheel. It is set to be the same value. The second nozzle is provided with a fixed blade for determining the direction of the flow of exhaust gas from the nozzle to the inter-blade channel. The fixed blade is inclined so that the portion closer to the turbine wheel is positioned forward in the rotation direction of the wheel so that the flow of the exhaust gas flows in a direction preferable for the rotation of the turbine wheel.

  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 flow path through the second nozzle is prohibited, and the inflow of exhaust gas into the inter-blade flow path is restricted to the first nozzle only. Is done from. 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, when the internal combustion engine is rotating at a medium to high speed, the control valve is opened to allow the exhaust to flow into the inter-blade flow path through the second nozzle, and the control valve opens more widely as the engine speed increases. Thus, the opening degree of the control valve is controlled. As a result, the flow of exhaust gas from the second nozzle to the inter-blade flow path during medium-high rotation of the internal combustion engine is suppressed while the exhaust flow rate increases as the engine speed increases and the pressure in the vicinity of the first nozzle becomes too high. Can be determined in a preferable direction for the rotation of the turbine wheel by the fixed blades of the nozzle.

  Here, assuming that both the first nozzle and the second nozzle are positioned corresponding to the inlet of the inter-blade channel, when the exhaust flows into the inter-blade channel from only the first nozzle, There is a region where exhaust does not flow in the portion corresponding to the second nozzle at the entrance of the inter-channel. For this reason, a vortex is generated in a region where the exhaust does not flow at the inlet of the flow path between the blades, and the rotational efficiency of the turbine with respect to the flow of the exhaust gas in the flow path between the blades is reduced. However, regarding such a problem, as disclosed in Patent Document 1, only the first nozzle is positioned so as to correspond to the inlet of the inter-blade flow path, and the inlet is formed in a size corresponding to the first nozzle. At the same time, the second nozzle can be avoided by being positioned so as to correspond to the middle part of the flow path between the blades.

  By the way, when the opening degree of the control valve located upstream of the second nozzle is controlled as described above, when the opening degree of the control valve is small during the middle rotation of the internal combustion engine, the exhaust gas has passed through the valve. Immediately after that, a rapid expansion of the gas distribution area occurs. When the above-described gas flow area suddenly expands on the exhaust flow path to the inter-blade flow path of the turbine wheel, the flow of the exhaust gas is separated from the wall surface of the exhaust flow path at that portion. Leads to loss of fluid energy of the exhaust. As a result, the rotational efficiency when the exhaust passes through the inter-blade flow path of the turbine wheel and rotates the wheel is lowered, and the supercharging efficiency of the turbocharger is lowered. Further, when the internal combustion engine is running at a low speed and the control valve is closed, it is inevitable that the exhaust gas flowing from the first nozzle to the inter-blade channel flows into the second nozzle side. And, since the exhaust flow into the second nozzle causes a disturbance in the exhaust flow in the inter-blade flow path, the rotation efficiency when rotating the turbine wheel decreases due to the disturbance in the exhaust flow, and the turbocharger Supercharging efficiency decreases.

Therefore, instead of the control valve, as shown in Patent Document 2, the nozzle moves to the vicinity of the turbine wheel in the second nozzle in the center line direction of the second nozzle, and at the outlet portion of the nozzle, the inter-blade flow It is conceivable to provide an annular coupler that makes the gas flow area of the portion immediately upstream of the path variable. In this case, the gas flow area that can be changed by the coupler is the gas flow area of the outlet portion of the second nozzle (immediately upstream of the flow path between the blades). During the middle rotation, there is no sudden expansion of the gas distribution area on the exhaust distribution path reaching the flow path between the blades of the turbine wheel. Therefore, as described above, the loss of fluid energy of the exhaust gas does not occur, the rotational efficiency when the exhaust gas rotates through the passage between the blades of the turbine wheel, and the turbocharger is supercharged. The efficiency is not reduced. In addition, since the coupler is provided in the vicinity of the turbine wheel, when the second nozzle is closed by the coupler during low rotation of the internal combustion engine, the exhaust gas flowing from the first nozzle to the inter-blade channel is directed to the second nozzle side. Inflow is avoided. Therefore, the exhaust flow in the inter-blade channel does not disturb the exhaust flow in the inter-blade channel due to the flow of the exhaust into the second nozzle, and the rotation efficiency when rotating the turbine wheel due to the disturbance of the exhaust flow It can be avoided that the turbocharger supercharging efficiency decreases.
JP 2006-37818 A (paragraphs [0020] to [0022], FIG. 1) JP 2003-522310 A (paragraph [0014], FIG. 1)

  By the way, in the turbocharger, in order to determine the direction of the flow of exhaust gas from the second nozzle to the inter-blade flow path in a preferable direction for the rotation of the turbine wheel, the second nozzle must be provided with fixed blades. Even if the turbocharger is provided with the coupler, the coupler does not have a function of determining the direction of the exhaust flow from the second nozzle to the inter-blade flow path as a preferable direction for the rotation of the turbine wheel. For the purpose of providing a function, it is necessary to provide a fixed blade on the second nozzle. Therefore, in any case, an increase in labor and cost of providing fixed blades on the second nozzle cannot be ignored.

  In the turbocharger, if the coupler is provided in the vicinity of the turbine wheel, the fixed blade of the second nozzle must be moved to the upstream side of the exhaust by the amount of the coupler. However, with respect to the fixed blade for determining the direction of the flow of exhaust gas from the second nozzle to the inter-blade flow path, the function of determining the flow direction of the exhaust gas in the fixed blade as it is positioned upstream of the exhaust gas. Decreases. Therefore, if the position of the fixed blade is changed to the upstream side of the exhaust by the amount of the coupler, the fixed blade may not be able to determine the direction of the exhaust flow in a direction preferable for the rotation of the turbine wheel.

  The present invention has been made in view of such a situation, and an object of the present invention is to make the gas flow area of the second nozzle variable in the vicinity of the turbine wheel, and the flow path between the second nozzle and the blades. It is an object of the present invention to provide a turbocharger in which the direction of the flow of exhaust gas into the turbine can be accurately determined in a direction preferable for the rotation of the turbine wheel without using fixed blades.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, a turbine scroll provided around the turbine wheel to which the exhaust gas of the internal combustion engine is sent, and the exhaust gas flowing along the circumferential direction of the turbine wheel in the turbine scroll. And a second nozzle that guides the exhaust gas in the turbine scroll to a middle portion of the inter-blade channel. In the turbocharger in which the turbine wheel rotates through inflow of exhaust gas, a partition provided around the turbine wheel and in the vicinity of the middle portion of the inter-blade flow path so as to surround the turbine wheel in the circumferential direction, and the partition Formed in the turbine scroll and communicating with the middle portion of the inter-blade flow path, and provided in the hole, the turbine wheel A flow control valve that opens and closes the hole by rotating about an axis extending in parallel with the center line of the engine, and the flow control valve is disposed upstream of the exhaust flow direction in the turbine scroll. The hole is opened by rotating the end portion positioned so as to protrude from the hole to the turbine scroll side, and the hole is closed by rotating the end portion so as to be accommodated in the hole. The gist of the invention is that the second nozzle is formed between the opposed surfaces of the valve that approaches and separates when the flow control valve rotates and the inner surface of the hole.

  According to the said structure, a 2nd nozzle is formed between the opposing surfaces of the flow control valve provided in the hole of the partition located in the turbine wheel vicinity, and the inner surface of the said hole, By rotating this valve, The gas distribution area of the second nozzle is variable. Since this flow control valve is located in the vicinity of the turbine wheel, the gas flow area of the second nozzle can be varied in the vicinity of the turbine wheel. Further, regarding the expansion of the gas flow area of the second nozzle by the rotation of the flow control valve, the end portion of the valve located on the upstream side in the exhaust flow direction in the turbine scroll extends from the hole to the turbine scroll side. This is realized by rotating the valve so as to protrude. Therefore, the opposed surfaces of the valve and the inner surface of the hole that are separated from each other by the rotation of the flow control valve are inclined so as to approach the turbine wheel toward the downstream side in the exhaust flow direction in the turbine scroll. For this reason, the second nozzle formed on the opposite surface of the flow control valve and the inner surface of the hole is similarly inclined, and thereby the direction of the flow of exhaust gas from the second nozzle to the inter-blade flow path can be made without a fixed blade. It can be determined in a preferred direction for the rotation of the turbine wheel.

  According to a second aspect of the present invention, in the first aspect of the invention, the surface on the turbine wheel side of the flow control valve when the hole is closed is the same curved surface as the surface on the turbine wheel side of the partition wall. The gist is that it is curved so as to be located above.

  According to the above configuration, when the flow control valve is rotated so as to close the hole so that the gas flow area of the second nozzle is “0”, the surface on the turbine wheel side of the valve is on the turbine wheel side of the partition wall. The surface, in other words, the surface around the opening on the turbine wheel side of the hole is located on the same curved surface. Therefore, it is possible to suppress the exhaust gas flowing from the first nozzle to the inter-blade flow path from flowing into the hole, and to prevent the exhaust flow in the inter-blade flow path from being disturbed by the exhaust flow. For this reason, it is possible to avoid a decrease in the rotational efficiency when the turbine wheel is rotated by the exhaust due to the disturbance of the exhaust flow in the inter-blade flow path, and a decrease in the turbocharger supercharging efficiency.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, with respect to the opposing surface between the flow control valve and the inner side surface of the hole when the hole is opened, the wheel becomes closer to the turbine wheel. As for the inclination of the facing surface, the direction of the flow of the exhaust gas flowing through the second nozzle formed between the facing surfaces and flowing into the inter-blade channel is determined. The gist of the present invention is that the direction is optimal for the rotation of the turbine wheel.

  According to the above configuration, the direction of the exhaust flow from the second nozzle to the inter-blade flow path is determined to be the optimal direction for the rotation of the turbine wheel, so that the rotation efficiency when rotating the turbine wheel by the exhaust is the best. Therefore, the turbocharger supercharging efficiency can be made the best state.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, with respect to the hole and the flow rate control valve, a width in a center line direction of the turbine wheel is between the blades. A portion that extends downstream from the outlet of the flow path and extends downstream from the outlet of the inter-blade flow path in the flow control valve has a protrusion that protrudes toward the center line of the turbine wheel. The protrusion is formed and is positioned so as to intersect with the inner surface of the hole forming the second nozzle when the flow control valve is closed.

  According to the above configuration, when the opening of the flow rate control valve is small and the intersection between the protrusion and the inner surface of the hole is large, the exhaust flow may flow from the second nozzle to the downstream of the turbine wheel. Is prohibited by the protrusion, so that all the exhaust gas flowing out from the second nozzle flows into the inter-blade channel. When the flow control valve is rotated in the valve opening direction from that state, the intersection between the protrusion and the inner surface of the hole becomes smaller, and the flow of exhaust gas from the second nozzle to the downstream of the turbine wheel is reduced. Since it is allowed little by little, some of the exhaust gas flowing out from the second nozzle begins to escape downstream of the turbine wheel without passing through the inter-blade channel. Then, the smaller the intersection between the protrusion and the inner surface of the hole, the greater the amount of exhaust that flows from the second nozzle downstream of the turbine wheel without passing through the inter-blade passage. Therefore, when the internal combustion engine is running at medium to high speeds and the exhaust flow rate increases as the engine rotational speed increases, the flow control valve is gradually turned from the closed state to the valve opening direction as the engine rotational speed increases. By moving the air, a quantity of exhaust that is preferable for the rotation of the turbine wheel flows from the second nozzle to the flow path between the blades, and the exhaust that exceeds the required amount bypasses the flow path between the blades to the downstream side of the turbine wheel. It can flow. Thereby, when the exhaust gas flow rate gradually increases as the operation region of the internal combustion engine changes from the middle rotation region to the high rotation region, the rotation efficiency of the turbine wheel is maintained in a suitable state in the middle rotation region, As a result, the supercharging efficiency of the turbocharger can be maintained in a suitable state. Further, in the high engine speed range, it is possible to suppress the deterioration of exhaust performance due to an increase in exhaust gas flow rate and an increase in exhaust resistance and a decrease in high speed performance of the internal combustion engine. Furthermore, the bypass of the exhaust inter-blade flow path in the high rotation range for suppressing the deterioration of the high speed performance of the internal combustion engine can be realized without adding a mechanism such as a waste gate valve.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein a plurality of the holes and the flow rate control valve are provided at equal intervals in the rotation direction of the turbine wheel. The summary.

  When the exhaust flows from the second nozzle to the inter-blade flow path, the force generated by the exhaust acts on the turbine wheel. Therefore, when only one second nozzle is formed, the turbine wheel receives the force from the exhaust at only one place in the circumferential direction, and the turbine wheel rotates smoothly based on the action of the force. There is a risk that it will not. However, according to the above configuration, the plurality of second nozzles are formed at equal intervals in the rotation direction of the turbine wheel. It acts equally on the turbine wheel in the circumferential direction. Therefore, the force by the exhaust acts on the turbine wheel, so that the turbine wheel does not rotate smoothly.

[First Embodiment]
Hereinafter, a first embodiment of 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 fixed to one end portion (left 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 centered on the center line thereof, that is, the axis of the rotor shaft 13, and a blade-to-blade channel 16 is formed between the blades 15.

  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. Inside the turbine scroll 17 is a scroll passage 19 that communicates with an exhaust passage of the internal combustion engine, and the exhaust of the internal combustion engine is fed into the scroll passage 19 from the exhaust passage. The exhaust gas fed into the scroll passage 19 in the turbine scroll 17 is caused to flow through the inter-blade channel 16 of the turbine wheel 14, whereby 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.
Inside the turbine scroll 17, a nozzle block 18 provided so as to surround the shaft 13 in the circumferential direction is fixed to a portion near the rotor shaft 13, and the wheel 14 is arranged in the circumferential direction near the turbine wheel 14. A partition wall 20 provided so as to surround is attached. A first nozzle 22 is formed between the nozzle block 18 and the partition wall 20 to guide the exhaust gas in the scroll passage 19 to the inlet 16 a of the inter-blade channel 16 of the turbine wheel 14. In addition, the size of the inlet 16 a of the inter-blade channel 16 is formed to a size corresponding to the first nozzle 22.

  Between the opposing nozzle wall surfaces of the first nozzle 22, in the portion near the inter-blade channel 16 of the turbine wheel 14, the gas flow area of the first nozzle 22 and the exhaust gas flowing from the nozzle 22 to the inter-blade channel 16. A low-speed stationary blade 24 for setting the direction is fixed. A plurality of the low-speed stationary blades 24 are provided around the turbine wheel 14 at equal intervals along the circumferential direction as shown in FIG. In addition, the figure is the figure which looked at the turbine scroll 17, the 1st nozzle 22, the fixed blade 24 for low speeds, etc. of FIG. 1 from the arrow AA direction.

  With regard to the gas flow area of the first nozzle 22, the flow between the blades of the turbine wheel 14 through the first nozzle 22 from the scroll passage 19 when the internal combustion engine rotates at low speed through the setting of the interval and inclination of the low-speed stationary blades 24. The flow rate of the exhaust gas flowing into the passage 16 is set to a value that can effectively rotate the wheel 14. Further, regarding the direction of the exhaust gas flowing from the first nozzle 22 to the inter-blade channel 16, it is preferable for the rotation of the turbine wheel 14 when the internal combustion engine is rotated at low speed through the setting of the interval and the inclination of the low-speed stationary blades 24. To be in the direction.

  FIG. 3 is a cross-sectional view of the partition wall 20 of FIG. 1 as viewed from the direction of the arrow BB. As shown in the figure, the partition wall 20 is formed with a hole 21 connected to the middle portion 16b of the inter-blade channel 16 and to the scroll passage 19 via the upstream portion of the first nozzle 22 (FIG. 1). A flow rate control valve 25 that opens and closes the hole 21 is provided in the hole 21. The direction of exhaust flow in the scroll passage 19 is the direction of arrow Y1 in FIG.

  In the flow control valve 25, the downstream end in the direction of the arrow Y <b> 1 is fixed to a shaft 26 extending in parallel with the center line of the turbine wheel 14, and is rotatable about the shaft 26. Then, the hole 21 is opened by rotating the valve 25 so that the upstream end of the flow rate control valve 25 in the direction of the arrow Y1 protrudes from the hole 21 to the turbine scroll 17 side. The hole 21 is closed by rotating the valve 25 so as to be accommodated in the valve 21. A surface 25a on the turbine wheel 14 side of the flow control valve 25 is a surface facing the inner surface 21a of the hole 21 when the valve 25 is opened. A second nozzle 23 that guides the exhaust of the scroll passage 19 (FIG. 1) to the midway portion 16b of the inter-blade channel 16 is formed between the opposing surface 25a and the inner surface 21a.

  On the surface 25a of the flow control valve 25, the portion near the downstream end in the arrow Y1 direction is on the same curved surface as the surface 20a on the turbine wheel 14 side of the partition wall 20 when the valve 25 shown in FIG. 4 is closed. It is curved to be located at. Further, on the surface 25 a of the flow control valve 25, a portion near the upstream end in the direction of the arrow Y <b> 1 is formed in a shape that is in surface contact with the inner surface 21 a of the hole 21 when the valve 25 is closed. Further, when the flow control valve 25 is opened as shown in FIG. 3, the surface 25 a of the valve 25 and the inner side surface 21 a of the hole 21 that face each other are more forward in the rotational direction of the wheel 14 as they approach the turbine wheel 14. It inclines so that it may go to (arrow Y1 direction front). Regarding the inclination of the surface 25a and the inner surface 21a, the flow direction (arrow Y2 direction) of the exhaust gas that passes through the second nozzle 23 formed between the surfaces 25a and 21a and flows into the inter-blade channel 16 is the turbine. The direction is set to be optimal for the rotation of the wheel 14.

Next, the operation mode of the flow control valve 25 will be described.
When the internal combustion engine is running at a low speed and the exhaust flow rate of the engine is small, the valve 25 sets the gas flow area of the second nozzle 23 to “0” through rotation about the shaft 26 of the flow control valve 25. Therefore, the valve closing state shown in FIG.

  In this case, the exhaust gas in the scroll passage 19 of FIG. 1 passes through only the first nozzle 22 and flows into the flow path 16 from the inlet 16a of the flow path 16 between the blades in the turbine wheel 14, and the flow path 16 between the blades. After passing through, the turbine wheel 14 exits to the downstream side. At this time, the flow velocity of the exhaust gas flowing into the inter-blade channel 16 from the first nozzle 22 becomes a value that allows the turbine wheel 14 to be effectively rotated by the low-speed stationary blade 24 when the internal combustion engine is rotated at a low speed. . Further, the flow direction of the exhaust gas from the first nozzle 22 to the inter-blade channel 16 is set to a direction suitable for the rotation of the turbine wheel 14 when the internal combustion engine is rotated at low speed by the low-speed stationary blade 24. Therefore, even when the internal combustion engine has a low rotational speed at which the exhaust flow rate is low, the rotational efficiency of the turbine wheel 14 due to the exhaust flow is increased as much as possible, and as a result, the supercharging efficiency of the turbocharger 11 is increased as much as possible. it can.

  Further, the surface 25a of the flow control valve 25 that is closed as shown in FIG. 4 is a surface 20a on the turbine wheel 14 side of the partition wall 20, in other words, a surface around the opening of the hole 21 on the turbine wheel 14 side. It will be located on the same curved surface. Therefore, it is possible to suppress the exhaust gas flowing from the first nozzle 22 into the inter-blade channel 16 from flowing into the hole 21, and it is possible to prevent the exhaust flow in the inter-blade channel 16 from being disturbed by the inflow. For this reason, it is possible to avoid a decrease in the rotational efficiency when the turbine wheel 14 is rotated by the exhaust due to the disturbance of the exhaust flow in the inter-blade flow path 16 and the turbocharger 11 is not supercharged.

  When the internal combustion engine is rotating at medium and high speeds and the exhaust flow rate of the engine is large, as the engine rotational speed increases and the exhaust flow rate increases, the flow control valve 25 is shown in FIG. The valve 25 is displaced to the open side so that the gas flow area of the second nozzle 23 is increased.

  The flow control valve 25 is provided in the partition wall 20 in the vicinity of the turbine wheel 14, and is positioned in the vicinity of the midway part 16 b of the inter-blade channel 16. For this reason, the gas flow area of the second nozzle 23 can be varied by the flow rate control valve 25 in the vicinity of the turbine wheel 14 (more precisely, in the vicinity of the midway portion 16b of the inter-blade channel 16).

  Regarding the expansion of the gas flow area of the second nozzle 23 by the rotation of the flow control valve 25, the upstream end of the valve 25 in the direction of the arrow Y1 protrudes from the hole 21 to the turbine scroll 17 side (upper side in the figure). This is realized by rotating the valve 25 as described above. At this time, the surface 25a of the valve 25 and the inner side surface 21a of the hole 21 which are separated from each other by the rotation of the flow control valve 25 are inclined so as to approach the turbine wheel 14 toward the downstream side in the arrow Y1 direction. For this reason, the second nozzle 23 formed between the surfaces 25a and 21a is similarly inclined, whereby the flow direction of the exhaust gas from the second nozzle 23 to the inter-blade channel 16 (arrow Y2 direction) is changed to the turbine wheel. The direction can be determined in a preferred direction for 14 rotations.

  Further, as described above, as the exhaust gas flow rate increases as the engine rotational speed increases, the flow rate control valve 25 is greatly rotated in the valve opening direction, and the gas flow area of the second nozzle 23 is increased. As a result, the flow rate of the exhaust gas flowing into the inter-blade channel 16 from the second nozzle 23 can be maintained at a value preferable for the rotation of the turbine wheel 14 from the middle rotation to the high rotation of the internal combustion engine. Further, when the engine rotational speed increases from medium to high rotation speed of the internal combustion engine, the exhaust flow to the downstream side of the turbocharger 11 worsens as the exhaust flow rate increases, and the pressure near the second nozzle 23 increases. It can also be prevented that the engine operation becomes too high, thereby adversely affecting the engine operation.

According to the embodiment described in detail above, the following effects can be obtained.
(1) The flow rate control valve 25 for making the gas flow area of the second nozzle 23 variable is provided in the partition wall 20 in the vicinity of the turbine wheel 14, and is positioned in the vicinity of the middle portion 16 a of the inter-blade channel 16. . For this reason, the gas flow area of the second nozzle 23 can be varied by the flow rate control valve 25 in the vicinity of the middle portion 16 a of the inter-blade channel 16. Therefore, the fluid energy of the exhaust gas flowing into the inter-blade channel 16 from the second nozzle 23 is lost, as in the case where the gas flow area of the second nozzle 23 is variable at a position away from the inter-blade channel 16, Accordingly, it is possible to avoid the rotational efficiency of the turbine wheel 14 from being lowered and the supercharging efficiency of the turbocharger 11 from being lowered.

  (2) Expansion of the gas flow area of the second nozzle 23 is realized by rotating the flow control valve 25 as described above. The surface 25a of the flow control valve 25 and the inner side surface 21a of the hole 21 that are separated from each other through such rotation are inclined so as to approach the turbine wheel 14 toward the downstream side in the direction of the arrow Y1. For this reason, the second nozzle 23 is similarly inclined, and the direction of the flow of exhaust gas from the nozzle 23 to the inter-blade channel 16 is determined as a preferable direction for the rotation of the turbine wheel 14. This means that the surface 25a of the flow control valve 25 and the inner surface 21a of the hole 21 can obtain the same effect as the case where the second nozzle 23 is provided with a fixed blade for determining the flow direction of the exhaust gas. is doing. Therefore, the surface 25a, 21a can obtain the above-described effect without providing the second nozzle 23 with fixed wings, and can eliminate an increase in labor and cost due to the provision of the fixed wings.

  (3) Regarding the inclination of the face 25a and the inner face 21a that face each other when the flow control valve 25 is opened, the flow direction of the exhaust gas that passes through the second nozzle 23 and flows into the inter-blade flow path 16 is the turbine. The direction is set to be optimal for the rotation of the wheel 14. Therefore, the rotational efficiency when rotating the turbine wheel 14 by the exhaust can be made the best state, and the supercharging efficiency of the turbocharger 11 can be made the best state.

[Second Embodiment]
Next, 2nd Embodiment of this invention is described based on FIGS.
In this embodiment, when the flow rate control valve 25 of the first embodiment has a high rotation speed of the internal combustion engine and the exhaust flow rate of the engine increases, the exhaust gas bypasses the inter-blade passage 16 of the turbine wheel 14. A function of flowing to the downstream side of the wheel 14 is provided.

  FIG. 5 is an enlarged cross-sectional view showing the flow rate control valve 25 of this embodiment, the partition wall 20 provided with the valve 25, and the like. FIG. 6 is a cross-sectional view of the flow control valve 25 and the partition wall 20 of FIG. 5 as viewed from the direction of the arrow CC.

  As shown in FIG. 6, the width W1 of the flow rate control valve 25 in the center line direction of the turbine wheel 14 and the width W2 of the hole 21 in the center line direction of the turbine wheel 14 are determined by the outlet 16c of the inter-blade flow path 16. It extends to the downstream side (left side in the figure) beyond. A protrusion 27 that protrudes toward the center line side (lower side in the figure) of the turbine wheel 14 is formed at a portion of the flow rate control valve 25 that extends downstream from the outlet 16c of the inter-blade channel 16. . The surface 27a on the turbine wheel 14 side of the protrusion 27 is curved so as to be positioned on the same curved surface as the surface 20a on the turbine wheel 14 side of the partition wall 20 when the flow control valve 25 is closed. Further, when the flow rate control valve 25 is closed, the protrusion 27 is positioned so as to intersect with the inner side surface 21a of the hole 21 forming the second nozzle 23 as shown by a two-dot chain line in FIG. .

  When the internal combustion engine is running at a low speed and the flow control valve 25 is closed, the gas flow area of the second nozzle 23 is “0”, so that no exhaust flows from the second nozzle 23. . Further, when the flow control valve 25 starts to open as the engine rotational speed increases and the valve 25 opens little, the intersection of the protrusion 27 and the inner surface 21a of the hole 21 (K in FIG. 5). Therefore, even if the exhaust gas flows from the second nozzle 23 to the downstream side of the turbine wheel 14, the flow of the exhaust gas is prohibited by the protrusion 27. As a result, all the exhaust gas flowing out from the second nozzle 23 flows into the inter-blade channel 16. When the flow rate control valve 25 is rotated in the valve opening direction as the engine rotational speed further increases, the intersection K between the protrusion 27 and the inner surface 21a of the hole 21 becomes smaller, and the second nozzle 23 To the downstream of the turbine wheel 14 is allowed little by little. For this reason, some of the exhaust gas flowing out from the second nozzle 23 begins to escape downstream of the turbine wheel 14 without passing through the inter-blade channel 16. As the intersection K between the protrusion 27 and the inner surface 21a of the hole 21 becomes smaller, the amount of exhaust gas that flows from the second nozzle 23 to the downstream side of the turbine wheel 14 without passing through the inter-blade channel 16 increases.

  FIG. 7 shows a state in which the intersection K (FIG. 5) is eliminated by opening the flow control valve 25. FIG. 8 is a cross-sectional view of the flow control valve 25 and the partition wall 20 of FIG. 7 as viewed from the direction of the arrow DD.

  When the internal combustion engine is rotating at a high speed and the exhaust flow rate of the engine is increased, the flow control valve 25 is opened as shown in FIG. It is displaced toward the turbine scroll 17 side with respect to the side surface 21a. As a result, the prohibition of the flow of exhaust gas from the second nozzle 23 to the downstream side of the turbine wheel 14 by the protrusion 27 is released, so that most of the exhaust gas flowing out from the second nozzle 23 is indicated by the arrow Y3. It flows to the downstream side of the turbine wheel 14 without passing through the inter-blade channel 16.

According to this embodiment, in addition to the effects (1) to (3) described in the first embodiment, the following effects can be obtained.
(4) When the internal combustion engine has a large exhaust flow rate and the engine is running at medium and high speeds, the flow rate control valve 25 is gradually rotated from the closed state to the open direction as the exhaust flow rate increases as the engine speed increases. As a result, the intersection K (FIG. 5) between the protrusion 27 of the valve 25 and the inner surface 21a of the hole 21 gradually decreases. As the intersection K decreases, the amount of exhaust flowing from the second nozzle 23 to the downstream side of the turbine wheel 14 without passing through the inter-blade channel 16 increases. Therefore, an amount of exhaust gas that is preferable for the rotation of the turbine wheel 14 flows from the second nozzle 23 to the inter-blade channel 16 from the middle rotation region to the high rotation region of the internal combustion engine. 16 can be bypassed and flow downstream of the turbine wheel 14. Thereby, in the middle rotation range, the rotation efficiency of the turbine wheel 14 can be maintained in a suitable state, and the supercharging efficiency of the turbocharger can be maintained in a suitable state. Further, in the high rotation region, most of the exhaust gas flowing out from the second nozzle 23 flows downstream of the turbine wheel 14 without passing through the inter-blade channel 16, so that the exhaust flow rate of the internal combustion engine increases. As a result, it is possible to suppress the deterioration of exhaust gas exhaust and the increase in exhaust resistance, thereby reducing the high speed performance of the internal combustion engine.

  (5) The effect of suppressing the reduction in the high-speed performance of the internal combustion engine is realized by the exhaust gas flowing around the inter-blade passage 16 and downstream of the turbine wheel 14 in the high speed region of the engine. The inter-blade channel 16 can be bypassed without adding a mechanism such as a waste gate valve.

[Other Embodiments]
In addition, each said embodiment can also be changed as follows, for example.
A plurality of flow control valves 25 and holes 21 may be provided at equal intervals in the circumferential direction of the turbine wheel 14 with respect to the partition wall 20. Specifically, as shown in FIGS. 9 and 10, a plurality of flow control valves 25 and holes 21 are provided. 9 shows an example in which two flow control valves 25 and holes 21 are provided, and FIG. 10 shows an example in which three flow control valves 25 and three holes 21 are provided.

  The turbine scroll 17 may be partitioned 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.

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. The figure which looked at the turbine scroll, the 1st nozzle, the fixed blade for low speeds, etc. in the turbocharger of FIG. 1 from the arrow AA direction. Sectional drawing which looked at the partition and the flow control valve in the turbocharger of FIG. 1 from the arrow BB direction. Sectional drawing which shows the closed state of a flow control valve. Sectional drawing which shows the flow control valve and partition of 2nd Embodiment. Sectional drawing which looked at the flow control valve and partition of FIG. 5 from the arrow CC direction. Sectional drawing which shows the state which the said flow control valve opened. Sectional drawing which looked at the flow control valve and partition of FIG. 7 from the arrow DD direction. Sectional drawing which shows the other example of installation of the flow control valve to a partition. Sectional drawing which shows the other example of installation of the flow control valve to a partition.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Turbocharger, 12 ... Center housing, 13 ... Rotor shaft, 14 ... Turbine wheel, 15 ... Blade, 16 ... Inter-blade flow path, 16a ... Inlet, 16b ... Middle part, 16c ... Outlet, 17 ... Turbine scroll, 18 DESCRIPTION OF SYMBOLS ... Nozzle block, 19 ... Scroll passage, 20 ... Partition, 20a ... Surface, 21 ... Hole, 21a ... Inner surface, 22 ... First nozzle, 23 ... Second nozzle, 24 ... Low speed fixed blade, 25 ... Flow control valve 25a ... surface, 26 ... shaft, 27 ... projection, 27a ... surface.

Claims (5)

A turbine scroll that is provided around the turbine wheel and into which the exhaust gas of the internal combustion engine is sent, and a first that guides the exhaust gas that flows in the turbine scroll along the circumferential direction of the turbine wheel to the inlet of the inter-blade passage of the turbine wheel. In a turbocharger comprising a nozzle and a second nozzle that guides exhaust in the turbine scroll to a middle portion of the inter-blade channel, and the turbine wheel rotates through inflow of exhaust into the inter-blade channel.
A partition wall provided around the turbine wheel and in the vicinity of the middle portion of the inter-blade channel so as to surround the turbine wheel in the circumferential direction;
A hole formed in the partition wall to communicate the inside of the turbine scroll and the middle part of the flow path between the blades;
A flow control valve that opens and closes the hole by rotating about an axis that is provided in the hole and extends parallel to the center line of the turbine wheel;
With
The flow control valve opens the hole by rotating an end located on the upstream side in the exhaust flow direction in the turbine scroll so as to protrude from the hole to the turbine scroll side, and opens the end. The hole is closed by rotating so as to be accommodated in the hole,
The turbocharger, wherein the second nozzle is formed between opposing surfaces of the valve that approaches and separates when the flow rate control valve rotates and an inner surface of the hole. The turbocharger according to claim 1, wherein a surface on the turbine wheel side of the flow rate control valve when the hole is closed is curved so as to be positioned on the same curved surface as a surface on the turbine wheel side of the partition wall. . The opposed surface between the flow rate control valve and the inner surface of the hole when the hole is opened is inclined so as to be directed forward in the rotational direction of the wheel as it approaches the turbine wheel. The direction of the flow of exhaust gas that passes through the second nozzle formed between the opposing surfaces and flows into the inter-blade flow path is set to be an optimal direction for rotation of the turbine wheel. The turbocharger according to 1 or 2. Regarding the hole and the flow control valve, the width of the turbine wheel in the direction of the center line extends downstream beyond the outlet of the inter-blade channel,
A protrusion that protrudes toward the center line of the turbine wheel is formed in a portion that extends downstream from the outlet of the inter-blade channel in the flow control valve,
The said protrusion is located so that it may be in the state which cross | intersected the inner surface of the said hole which forms the said 2nd nozzle at the time of valve closing of the said flow control valve. The listed turbocharger. The turbocharger according to any one of claims 1 to 4, wherein a plurality of the holes and the flow rate control valve are provided at equal intervals in a rotation direction of the turbine wheel.

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