JP2010242520A - Variable capacity turbine and variable displacement turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detune a turbine impeller 33 in a specific high speed zone by simple additional work and simple design change, and to avoid the resonance of the turbine impeller 33. <P>SOLUTION: A notch 61 is formed at a part of an outer edge of each turbine blade 37, and an orienting direction of a tip of each notch 61 is perpendicular to an axial center of a turbine impeller 33. A recessed part 63 is formed at an outer edge of each turbine blade 37 and each of the recessed part 63 includes a progressive reduction area 63a in which a length from an axis C of the turbine impeller 33 progressively decreases toward a downstream side, and a progressive increase area 63b which is adjacent to a downstream side of the progressive reduction area 63a and in which a length from the axis C of the turbine impeller 33 progressively increases toward a downstream side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable capacity turbine that generates a rotational force by using pressure energy of a gas such as exhaust gas.

  In recent years, various developments have been made on variable capacity turbines used in, for example, variable capacity turbochargers. Patent Documents 1 and 2 disclose prior art variable capacity turbines. The configuration of the variable capacity turbine according to the prior art will be described as follows.

  The variable capacity turbine according to the prior art includes a turbine housing, and the turbine housing is provided in a bearing housing in the variable capacity turbocharger. A turbine impeller is rotatably provided in the turbine housing. The turbine impeller is integrally connected to a rotor shaft (turbine shaft) in a variable displacement turbocharger, and has a shaft center (turbine impeller). And a plurality of turbine blades provided at equal intervals in the circumferential direction on the outer peripheral surface of the turbine wheel. A plurality of variable nozzles are arranged at equal intervals in the circumferential direction on the inlet side (upstream side) of the turbine impeller in the turbine housing, and each variable nozzle has an axis parallel to the axis of the turbine impeller. It can be rotated around the heart.

  A gas inlet for taking in exhaust gas from the engine is formed at an appropriate position of the turbine housing. In addition, a turbine scroll passage is formed inside the turbine housing so as to surround a plurality of variable nozzles, and the turbine scroll passage communicates with a gas intake port so that exhaust gas can be taken in. It is. Further, a gas discharge port for discharging exhaust gas is formed on the outlet side (downstream side) of the turbine impeller in the turbine housing.

  Therefore, the exhaust gas taken into the turbine scroll flow path is circulated from the inlet side to the outlet side of the turbine impeller, thereby generating a rotational force (rotational torque) using the pressure energy of the exhaust gas to rotate the rotor shaft. Can be made.

  Here, when the flow rate of the exhaust gas is small (in other words, when the engine speed is in the low speed range), the plurality of variable nozzles are rotated in synchronization with the direction in which the variable nozzles are throttled to move to the turbine impeller side. The flow rate of the exhaust gas to be supplied is increased to ensure a sufficient amount of work for the turbine impeller. On the other hand, when the flow rate of the exhaust gas is large (in other words, when the engine speed is in the high speed range), the throat area of the variable nozzle is increased and a large amount of exhaust gas is supplied to the turbine impeller side. Thereby, regardless of the flow rate of the exhaust gas, the rotational force can be generated sufficiently and stably by the variable capacity turbine, and the performance of the variable capacity turbine can be enhanced.

  Note that, as prior art related to the present invention, there is one shown in Patent Document 3 in addition to Patent Document 1 and Patent Document 2.

JP 2007-231934 A JP 2003-27951 A Japanese Patent Laid-Open No. 5-149103

  As described above, although the performance of the variable displacement turbine can be improved by a plurality of variable nozzles, the excitation frequency (turbine blade excitation frequency) due to the wake of the variable nozzle and the natural vibration of the turbine impeller If the numbers match, the turbine impeller will resonate. On the engine, the turbine pressure ratio increases and the excitation force increases as the turbine speed increases. When the turbine impeller reaches a specific high-speed rotation speed range, if the excitation frequency due to the wake of the variable nozzle matches the natural frequency of the turbine impeller, excessive vibration stress due to resonance occurs in the turbine blade, and the turbine impeller Impeller fatigue builds up. Therefore, by adjusting the excitation frequency by changing the number of variable nozzles, or by adjusting the natural frequency of the turbine impeller by changing the thickness distribution of the turbine blades, the specific frequency range of the turbine impeller can be adjusted. Must be detuned to avoid resonance of the turbine impeller.

  Further, the compressor capacity, that is, the compressor impeller specification changes depending on the engine specification, but even if the compressor impeller specification changes, the turbine impeller specification may not be changed within a predetermined range. In this case, since the operating rotational speed on the engine changes, in some cases, it is necessary to adjust the natural frequency of the turbine impeller to reduce the frequency of resonance.

  However, changing the number of variable nozzles or changing the thickness distribution of the turbine blades involves a significant design change of the variable displacement turbine, and a great deal of labor and cost is required to finally finish the variable displacement turbine. Will be spent. That is, there is a problem that it is not easy to reduce labor and cost until the variable capacity turbine is finally finished while suppressing a decrease in fatigue life of the variable capacity turbine.

  In addition, as shown in Patent Document 3, even when the natural frequency of the turbine blade is adjusted by integrating the divided turbine blades by a combination of the projecting portion and the notch portion, the turbine blade is greatly reduced. This involves a design change and causes the same problem as described above.

  Therefore, an object of the present invention is to provide a variable capacity turbine having a novel configuration that can solve the above-described problems.

  As a result of repeating various trials and errors in order to solve the above-mentioned problems, the inventor of the present invention, as shown in FIG. 3, the direction of the tip of the turbine impeller is a part of the outer edge of each variable nozzle. By forming a notch perpendicular to the axis C, as shown in FIG. 4, the turbine impeller eigenvalue (primary eigenvalue, secondary eigenvalue, tertiary eigenvalue) is reduced, and the turbine impeller is reduced. New knowledge that the natural frequency can be adjusted has been obtained, and the present invention has been completed.

  Here, FIG. 3 is a half sectional view of the turbine impeller according to the new knowledge, and FIG. 4 is a diagram showing the relationship between the relative notch depth and the eigenvalue change rate of the turbine impeller, where the eigenvalue change rate of the turbine impeller is It is obtained by vibration analysis. The relative notch depth is the ratio (D2 / D1) of the notch depth D2 to the radial length D1 of the turbine impeller at the notch formation portion of the turbine blade, and is an eigenvalue of the turbine impeller. The rate of change is the rate of change in the eigenvalue of a turbine impeller with a notch relative to the eigenvalue of a turbine impeller without a notch.

  A first feature of the present invention is a variable displacement turbine that generates rotational force (rotational torque) by using pressure energy of gas, and is provided rotatably in a turbine housing and rotatable around an axis. A turbine impeller having a plurality of turbine blades provided at intervals on the outer peripheral surface of the wheel and the turbine wheel, and an inlet side (upstream side) of the turbine impeller in the turbine housing are spaced apart in the circumferential direction. And a plurality of variable nozzles arranged around and rotatable about an axis parallel to the axis of the turbine impeller, and capable of taking gas into the turbine housing Is formed so as to surround a plurality of the variable nozzles, and the outlet side (downstream) of the turbine impeller in the turbine housing ) Is formed with a gas discharge port for discharging gas, a notch is formed in a part of the outer edge of each turbine blade, and the direction of the tip of each notch (in other words, the depth direction of each notch) is The gist is that it is perpendicular (perpendicular direction) to the axis of the turbine impeller.

  In the specification and claims of the present application, “provided” means not only directly provided but also indirectly provided via an interposed member such as a bracket. Similarly, “arranged” means not only directly disposed but also indirectly disposed via an interposed member such as a bracket.

  According to the first feature, by causing the gas taken into the turbine scroll passage to flow from the inlet side to the outlet side of the turbine impeller, the rotational energy (rotational torque) is generated using the pressure energy of the gas. Can do.

  Here, when the flow rate of the gas is small, the flow velocity of the gas supplied to the turbine impeller side is increased by rotating the plurality of variable nozzles synchronously in the direction of constricting, and the turbine impeller Ensure sufficient work load. On the other hand, when the flow rate of the gas is large, the throat area of the variable nozzle is increased by rotating a plurality of the variable nozzles synchronously in the opening direction, and a large amount of exhaust gas is supplied to the turbine impeller side. Supply. Accordingly, the variable displacement turbine can sufficiently and stably generate a rotational force regardless of the gas flow rate, and the performance of the variable displacement turbine can be improved (according to the first feature). General action).

  A notch is formed in a part of the outer edge of each turbine blade, and the orientation direction of the tip of each notch is perpendicular to the axis of the turbine impeller. The natural frequency (primary eigenvalue, secondary eigenvalue, and tertiary eigenvalue) of the turbine impeller can be reduced to adjust the natural frequency of the turbine impeller. Thereby, by performing simple additional machining, the turbine impeller can be detuned with respect to a specific high-speed rotation speed range, and resonance of the turbine impeller can be avoided. ).

  A second feature of the present invention is a variable displacement turbine that generates rotational force (rotational torque) by using pressure energy of gas, and is provided rotatably in a turbine housing and rotatable around an axis. A turbine impeller having a plurality of turbine blades provided at intervals on the outer peripheral surface of the wheel and the turbine wheel, and an inlet side (upstream side) of the turbine impeller in the turbine housing are spaced apart in the circumferential direction. And a plurality of variable nozzles arranged around and rotatable about an axis parallel to the axis of the turbine impeller, and capable of taking gas into the turbine housing Is formed so as to surround a plurality of the variable nozzles, and a gas is provided at an outlet side of the turbine impeller in the turbine housing. A gas discharge port for discharging is formed, and a concave portion (pseudo-notch) is formed at the outer edge of each turbine blade. Each concave portion has a length from the axis of the turbine impeller (a length in the radial direction) on the downstream side. A gradually decreasing region that gradually decreases toward the tip of the turbine impeller, and the length from the axis of the turbine impeller that is adjacent to the downstream side of the gradually decreasing region and gradually increases toward the downstream side. The gist is to have a gradually increasing region.

  According to the second feature, in addition to the same operation as the general operation according to the first feature described above, the recess is formed on the outer edge of each turbine blade, and each recess has the gradually decreasing region and the gradually increasing region. Therefore, if the above-mentioned new knowledge is applied by analogy, the natural frequency (primary eigenvalue, secondary eigenvalue, tertiary eigenvalue) of the turbine impeller is reduced and the natural frequency of the turbine impeller is adjusted. it can. As a result, it is possible to avoid resonance of the turbine impeller by detuning with respect to a specific high-speed rotation speed range of the turbine impeller simply by making a simple design change (specific operation by the second feature). ).

  According to a third aspect of the present invention, there is provided the variable capacity turbocharger that supercharges the air supplied to the engine by using the energy of the exhaust gas from the engine. The gist is that a variable displacement turbine is provided.

  According to the 3rd characteristic, there exists an effect | action similar to the effect | action by the 1st characteristic or the 2nd characteristic.

  According to the present invention, the resonance of the turbine impeller can be avoided by performing detuning with respect to a specific high-speed rotation speed range of the turbine impeller simply by performing simple additional processing or simple design change. Thus, it is possible to sufficiently reduce labor and cost until the variable capacity turbine is finally finished while suppressing the speed of fatigue accumulation of the variable capacity turbine.

It is an expanded sectional view of the arrow view part II in FIG. 1 is a cross-sectional view of a variable capacity turbocharger according to an embodiment of the present invention. It is a half sectional view of a turbine impeller concerning new knowledge. It is a figure which shows the relationship between a relative notch depth and the eigenvalue change rate of a turbine impeller. It is a half sectional view of a turbine impeller concerning a modification of an embodiment of the present invention. It is a half sectional view of a turbine impeller concerning a modification of an embodiment of the present invention. It is a half sectional view of a turbine impeller concerning a modification of an embodiment of the present invention.

An embodiment of the present invention will be described with reference to FIGS.
In the drawings, “F” indicates the forward direction, and “R” indicates the backward direction.

  As shown in FIGS. 1 and 2, the variable displacement turbocharger 1 according to the embodiment of the present invention supercharges air supplied to the engine using the energy of exhaust gas from the engine (not shown). (Compressed). The specific configuration of the variable capacity turbocharger 1 is as follows.

  The variable capacity turbocharger 1 includes a bearing housing 3, and a radial bearing 5 and a pair of thrust bearings 7 are provided in the bearing housing 3. A rotor shaft (turbine shaft) 9 extending in the front-rear direction is rotatably provided. In other words, the bearing housing 3 is provided with the rotor shaft 9 rotatably via a plurality of bearings 5 and 7. Yes.

  A compressor 11 that compresses air by using centrifugal force is disposed on the rear side of the bearing housing 3, and a specific configuration of the compressor 11 is as follows.

  That is, a compressor housing 13 is provided on the rear side of the bearing housing 3, and a compressor impeller 15 is rotatably provided in the compressor housing 13. More specifically, a compressor wheel 17 is provided in the compressor housing 13, and the compressor wheel 17 is integrally connected to the front end portion of the rotor shaft 9 via a fixing nut 19. The impeller 15 can rotate around the axis C (in other words, the axis of the rotor shaft 9) C. Further, the outer peripheral surface of the compressor wheel 17 extends radially outward from the axial direction of the compressor impeller 15. Furthermore, a plurality of compressor blades 21 are provided on the outer peripheral surface of the compressor wheel 17 at equal intervals in the circumferential direction.

  An air intake 23 for taking in air is formed on the inlet side of the compressor impeller 15 in the compressor housing 13 (the front side of the compressor housing 13). The air intake 23 is connected via a connecting pipe (not shown). It can be connected to an air cleaner (not shown). An annular diffuser flow path 25 that pressurizes the compressed air is formed on the outlet side of the compressor impeller 15 between the bearing housing 3 and the compressor housing 13. The diffuser flow path 25 is an air intake port. 23 communicates. Further, a compressor scroll passage 27 is formed in the compressor housing 13 so as to surround the compressor impeller 15, and the compressor scroll passage 27 communicates with the diffuser passage 25. An air discharge port (not shown) for discharging compressed air is formed at an appropriate position of the compressor housing 13, and this air discharge port communicates with the compressor scroll flow path 27, and Can be connected to an air supply manifold (not shown).

  A variable capacity turbine 29 that generates a rotational force (rotational torque) using the pressure energy of the exhaust gas is disposed on the front side of the bearing housing 3. The specific configuration of the variable capacity turbine 29 is as follows. It becomes as follows.

  That is, a turbine housing 31 is provided on the front side of the bearing housing 3, and a turbine impeller 33 is rotatably provided in the turbine housing 31. More specifically, a turbine wheel 35 is provided in the turbine housing 31, and this turbine wheel 35 is integrally connected to the rear end portion of the rotor shaft 9, and is connected to the shaft of the turbine impeller 33. It can rotate around the center (in other words, the axis of the rotor shaft 9) C. Further, the outer peripheral surface of the turbine wheel 35 extends radially outward from the axial direction of the turbine impeller 33. Further, a plurality of turbine blades 37 are provided on the outer peripheral surface of the turbine wheel 35 at equal intervals in the circumferential direction.

  A variable nozzle unit 39 is disposed in the turbine housing 31 so as to surround the turbine impeller 33. More specifically, a nozzle ring 41 is provided on the radially outer side of the turbine impeller 33 in the turbine housing 31 via an attachment ring 43, and a plurality of shroud rings 45 (1 (Only one is shown) is provided integrally and spaced apart in the front-rear direction. A plurality of variable nozzles 49 are arranged at equal intervals in the circumferential direction between the nozzle ring 41 and the shroud ring 45, in other words, on the inlet side of the turbine impeller 33 in the turbine housing 31. The variable nozzle 49 is rotatable (swingable) around an axis parallel to the axis C of the turbine impeller 33. Here, the nozzle shafts 49 s of the plurality of variable nozzles 49 are interlocked and connected by a synchronization mechanism 51 as shown in Patent Document 1.

  A transmission shaft 53 is rotatably provided at the front lower portion of the bearing housing 3, and a front end portion of the transmission shaft 53 is an actuator such as a cylinder that rotates a plurality of variable nozzles 49 synchronously. The rear end of the transmission shaft 53 is connected to the synchronization mechanism 51 by connecting (interlocking connection) to a connection lever 55 (not shown).

  A gas intake (not shown) for taking in exhaust gas is formed at an appropriate position of the turbine housing 31, and this gas intake can be connected to an exhaust manifold (not shown) of the engine. In addition, a turbine scroll passage 57 is formed inside the turbine housing 31 so as to surround the turbine impeller 33. The turbine scroll passage 57 communicates with a gas intake port to collect exhaust gas. It is possible to enter. Further, a gas discharge port 59 for discharging exhaust gas is formed at the outlet side of the turbine impeller 33 in the turbine housing 31 (the rear side of the turbine housing 31). , And can be connected to an exhaust gas purification device (not shown) via a connecting pipe (not shown).

  In addition, a notch 61 is formed at a part of the outer edge of each turbine blade 37, and the directing direction of the tip of each notch 61 (in other words, the depth direction of each notch 61) is a turbine impeller. It is perpendicular to the 33 axis. Here, the orientation direction of the tip of each notch 61 is set as described above because the centrifugal force is applied to the turbine blade 37 during the operation of the variable displacement turbocharger 1 (the operation of the variable displacement turbine 29). This is to avoid the occurrence of excessive tensile stress.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  By causing the exhaust gas taken into the turbine scroll passage 57 from the gas inlet to flow from the inlet side to the outlet side of the turbine impeller 33, a rotational force (rotational torque) is generated using the pressure energy of the exhaust gas, The rotor shaft 9 and the compressor impeller 15 can be rotated integrally with the turbine impeller 33. Thereby, the air taken in from the air intake port 23 can be compressed and discharged from the air discharge port via the diffuser passage 25 and the compressor scroll passage 27, and the air supplied to the engine is supercharged. be able to.

  Here, when the flow rate of the exhaust gas is small (in other words, when the engine speed is in the low speed range), the actuator is rotated in synchronization with the direction in which the plurality of variable nozzles 49 are throttled by the actuator. The flow rate of the exhaust gas supplied to the impeller 33 is increased to ensure a sufficient amount of work for the turbine impeller 33. On the other hand, when the flow rate of the exhaust gas is large (in other words, when the engine speed is in the low speed range), the variable nozzles 49 are rotated in synchronization with the opening direction of the plurality of variable nozzles 49 by the actuator. The throat area of 49 is increased and a large amount of exhaust gas is supplied to the turbine impeller 33 side. As a result, the rotational capacity can be sufficiently and stably generated by the variable displacement turbine 29 regardless of the flow rate of the exhaust gas, and the performance of the variable displacement turbine 29 can be improved (variable displacement turbo). General action by charger 1).

  A notch 61 is formed in a part of the outer edge of each turbine blade 37, and the directing direction of the tip of each notch 61 is perpendicular to the axis C of the turbine impeller 33. By applying (see [Means for Solving the Problems]), it is possible to adjust the natural frequency of the turbine impeller 33 by reducing the natural value (primary eigenvalue, secondary eigenvalue, and tertiary eigenvalue) of the turbine impeller 33. Thus, by performing simple additional machining, the turbine impeller 33 can be detuned with respect to a specific high-speed rotation speed range, and resonance of the turbine impeller 33 can be avoided (variable displacement turbocharger 1 (variable Specific action by the displacement turbine 29).

  Therefore, according to the embodiment of the present invention, it is possible to sufficiently reduce labor and cost until the variable capacity turbine 29 is finally finished while suppressing the speed of fatigue accumulation of the variable capacity turbine 29 (variable capacity). Effect of the turbocharger 1 (variable capacity turbine 29)).

(Modification)
A modification of the present invention will be described with reference to FIGS.

  Instead of forming a notch 61 at a part of the outer edge of each turbine blade 37, as shown in FIGS. 5 (a), 5 (b), 6 (a), (b), and 7 (a), A recess (simulated cutout) 63 may be formed in a part of the outer edge of the turbine blade 37, and each recess 63 has a length from the axis C of the turbine impeller 33 (a length in the radial direction). Gradually decreases toward the downstream side (in other words, toward the front end side of the turbine impeller 33), and the length from the axis C of the turbine impeller 33 is adjacent to the downstream side of the gradually decreasing region 63a. It has a gradually increasing region 63b that gradually increases toward the downstream side. Further, instead of forming the recess 63 in a part of the outer edge of each turbine blade 37, as shown in FIG. 7B, the recess 63 may be formed in the entire outer edge of each turbine blade 37. I do not care.

  And according to the modification of the embodiment of the present invention, in addition to the general effect of the variable displacement turbocharger 1 described above, the recess 63 is formed in a part or the whole of the outer edge of each turbine blade 37, Since each recess 63 has a gradually decreasing region 63a and a gradually increasing region 63b, applying the analogy to the above-described new knowledge (see [Means for Solving the Problems]), the eigenvalue (primary value) of the turbine impeller 33 is applied. The natural frequency of the turbine impeller 33 can be adjusted by reducing the natural value, the secondary eigenvalue, and the tertiary eigenvalue). Thereby, it is possible to avoid resonance of the turbine impeller 33 by performing detuning with respect to a specific high-speed rotation speed range of the turbine impeller 33 only by making a simple design change.

  Therefore, also in the modified example of the embodiment of the present invention, the same effects as those obtained by the variable displacement turbine 29 described above are obtained.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, It can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

DESCRIPTION OF SYMBOLS 1 Variable displacement type turbocharger 3 Bearing housing 9 Rotor shaft 11 Compressor 13 Compressor housing 15 Compressor impeller 29 Variable displacement turbine 31 Turbine housing 33 Turbine impeller 35 Turbine wheel 37 Turbine blade 39 Variable nozzle unit 49 Variable nozzle 57 Turbine scroll channel 59 Gas outlet 61 Notch 63 Recess 63a Gradually decreasing area 63b Gradually increasing area

Claims (3)

In a variable capacity turbine that generates rotational force using the pressure energy of gas,
A turbine wheel provided in a turbine housing so as to be rotatable and rotatable around an axis, and a turbine impeller comprising a plurality of turbine blades spaced from each other on an outer peripheral surface of the turbine wheel;
A plurality of variable nozzles disposed around the inlet side of the turbine impeller in the turbine housing at intervals in the circumferential direction and rotatable about an axis parallel to the axis of the turbine impeller. ,
A turbine scroll flow path capable of taking gas into the turbine housing is formed so as to surround a plurality of the variable nozzles, and a gas discharge port for discharging gas is formed on the outlet side of the turbine impeller in the turbine housing. And
A variable displacement turbine characterized in that a notch is formed in a part of an outer edge of each turbine blade, and a directing direction of a tip of each notch is perpendicular to an axis of the turbine impeller. In a variable capacity turbine that generates rotational force using the pressure energy of gas,
A turbine wheel provided in a turbine housing so as to be rotatable and rotatable around an axis, and a turbine impeller comprising a plurality of turbine blades spaced from each other on an outer peripheral surface of the turbine wheel;
A plurality of variable nozzles disposed around the inlet side of the turbine impeller in the turbine housing at intervals in the circumferential direction and rotatable about an axis parallel to the axis of the turbine impeller. ,
A turbine scroll flow path capable of taking gas into the turbine housing is formed so as to surround a plurality of the variable nozzles, and a gas discharge port for discharging gas is formed on the outlet side of the turbine impeller in the turbine housing. And
A concave portion is formed on the outer edge of each turbine blade, and each concave portion has a gradually decreasing region in which the length from the axis of the turbine impeller gradually decreases toward the downstream side, and is adjacent to the downstream side of the gradually decreasing region and the turbine impeller. A variable capacity turbine characterized in that it has a gradually increasing region in which the length from the shaft center increases gradually toward the downstream side. In the variable capacity turbocharger that uses the energy of the exhaust gas from the engine to supercharge the air supplied to the engine,
A variable capacity type turbocharger comprising a variable capacity type turbine comprising the specific matters of the invention according to claim 1.

Images