JP5458585B2 - Impeller and impeller balance adjusting method - Google Patents

Description

The present invention is an impeller for use in turbocharger, and a method in which balance the impeller.

  A general turbine impeller will be described with reference to FIGS.

  Here, FIG. 5 is a side sectional view of a general turbine impeller, and FIG. 6 is a side sectional view of another general turbine impeller.

  As shown in FIGS. 5 and 6, a general turbine impeller 101A (101B) is used for a turbocharger (not shown) and rotates using the energy of exhaust gas from an engine (not shown). is there. A general turbine impeller 101 </ b> A (101 </ b> B) includes a turbine hub 103, and the turbine hub 103 is integrally connected to a rotor shaft (turbine shaft) 105 in a coaxial manner. Further, the outer peripheral surface of the turbine hub 103 extends radially outward from the axial direction of the turbine hub 103, and the turbine hub 103 has a fixing nut 107 on the tip side. Further, a plurality of turbine blades 109 are provided on the outer peripheral surface of the turbine hub 103 at intervals in the circumferential direction.

  On the other hand, in order to suppress vibration during rotation of the turbine impeller 101A (101B), it is necessary to perform balance adjustment (balance correction) based on the result of the dynamic balance test before finally finishing the turbine impeller 101A (101B). There is. Therefore, in the general turbine impeller 101A, a cutting process for balance adjustment (for balance correction) is performed on a part of the fixing nut 107 (the tip of the turbine hub 103) and a part of the flat rear surface of the turbine hub 103. ing. In the other general turbine impeller 101B, a balance adjusting cutting process is performed on a part of the fixing nut 107 and a part of the annular balance adjusting protrusion 111 formed on the rear surface of the turbine hub 103. Yes. In FIG. 5 and FIG. 6, a part (balance adjustment part) FP that has been subjected to the cutting process for balance adjustment is indicated by an imaginary line.

  In addition, there exist some which are shown to patent document 1 and patent document 2 as a prior art relevant to this invention.

JP 2001-254627 A Japanese Patent No. 3916146

  Incidentally, in recent years, in response to a request for improving the performance of the turbine impeller 101A (101B) (in other words, improving the performance of the turbocharger), the rotational speed (rotational speed) of the turbine impeller 101A (101B) tends to increase. When the rotation speed of the turbine impeller 101A (101B) increases, the following problem occurs.

  That is, when a general turbine impeller 101A is rotated at a high speed, as shown in FIG. 7A, an excessive stress is not generated in a region excluding the balance adjustment portion FP on the rear surface of the turbine hub 103. As shown in FIG. 7B, excessive stress is generated around the balance adjustment portion FP on the back surface of the turbine hub 103. Further, when another general turbine impeller 101B is rotated at a high speed, no excessive stress is generated around the balance adjustment portion FP on the back surface of the turbine hub 103 as shown in FIG. 8B. However, as shown in FIG. 8A, excessive stress is generated around the portion SP remaining as a part of the balance adjustment projection 111. Therefore, in the general turbine impeller 101A (101B), when the performance of the turbine impeller 101A (101B) is to be improved, the turbine hub 103 is likely to fail, and the durability of the turbine impeller 101A (101B) is increased. There is a problem that decreases. In other words, there is a problem that it is not easy to simultaneously improve the performance of the turbine impeller 101A (101B) and the durability of the turbine impeller 101A (101B).

  Here, FIG. 7A is a diagram showing the stress distribution in a part of the region excluding the balance adjustment portion on the back surface of the general turbine hub, and FIG. 7B is the balance on the back surface of the general turbine hub. FIG. 8A is a diagram showing the stress distribution in a part of the region including the adjustment part, and FIG. 8A is a diagram showing the stress distribution in a part of the region excluding the balance adjustment part on the back surface of another general turbine hub. (B) is a figure which shows the stress distribution of the one part area | region including the balance adjustment part in the back surface of another general turbine hub, Comprising: Stress distribution of the back surface of a turbine hub is FEM (Finite Element Method) analysis. The stress on the rear surface of the turbine hub is made dimensionless.

  Therefore, an object of the present invention is to provide an impeller or the like having a novel configuration that can solve the above-described problems.

  In order to solve the above-mentioned problems, the inventor of the present invention has repeated various trials and errors, and as a result, the turbine blade (an example of the blade) in an arbitrary side cross section parallel to the axis of the turbine hub (an example of the hub). The length from the hypothetical reference line passing through the base end of the radially outer edge and perpendicular to the turbine hub axis to the rear surface of the turbine hub increases gradually as it approaches the axis side of the turbine hub. In this case, even if the turbine impeller (an example of the impeller) is rotated at a high speed, as shown in FIGS. 4A and 4B, the balance adjustment part (balance correction part) FP is included and the turbine hub A novel finding that generation of excessive stress on the entire back surface can be sufficiently suppressed can be obtained, and the present invention has been completed.

  Here, FIG. 4A is a diagram showing a stress distribution in a partial region (region corresponding to the arrow IVA in FIG. 1) excluding the balance adjustment portion on the rear surface of the turbine hub according to the novel knowledge. 4 (b) is a diagram showing the stress distribution in a partial region (region corresponding to the arrow IVB in FIG. 1) including the balance adjustment portion on the rear surface of the turbine hub according to the novel knowledge. The stress distribution on the back surface of the turbine hub is obtained by FEM analysis, and the stress on the back surface of the turbine hub is made dimensionless.

A first feature of the present invention (a feature of the invention described in claim 1) is that, in an impeller that is used in a turbocharger and rotates using the energy of exhaust gas, the outer peripheral surface is directed from the axial direction to the radially outer side. And a hub that is partly subjected to cutting for balance adjustment based on the result of the dynamic balance test, and provided at the end of the exhaust gas outlet side of the hub. A fixing nut that has been subjected to a cutting process for adjusting the balance based on the outer peripheral surface of the hub, and is provided at intervals in the circumferential direction, and the leading edge is radially outward from the maximum diameter portion of the outer peripheral surface of the hub. comprising a plurality of blades located, and in any cross-sectional side view parallel to the axis of the hub, from the reference line vertical virtual base end of the leading edge to the axis of the street and the hub of said blade, said Until the back of the hub. The length, in each other so as to increase stepwise in accordance with approaches toward the axis of said hub, a portion subjected to cutting for the balance adjustment, a portion of the outer peripheral edge of the fixing nut, The gist of the invention is that it is a part of the outer peripheral edge of a step-like increasing part on the back surface of the hub and is located radially inward of the maximum diameter part of the trailing edge of the blade.

A second feature of the present invention (a feature of the invention described in claim 2) is a method for balancing an impeller used in a turbocharger and rotating using the energy of exhaust gas. The leading edge is located radially outward from the maximum diameter portion on the outer peripheral surface of the hub of the impeller, and passes through the proximal end of the leading edge of the blade in any side cross section parallel to the axis of the hub; The length from an imaginary reference line perpendicular to the hub axis to the back surface of the hub increases in a step shape as it approaches the shaft center side of the hub, and increases in a step shape on the back surface of the hub. while satisfying the condition that the part based on the dynamic balancing test results of the impeller of the hub, and a fixing nut provided on the end of the outflow side of the exhaust gas in the hub one Be those subjected to cutting for balance adjustment, a portion subjected to cutting for the balance adjustment, a portion of the outer peripheral edge of the fixing nut, the outer portion which increases in a stepwise manner on the rear of the hub The gist of the invention is that it is a part of the peripheral edge and is located radially inward of the maximum diameter part of the trailing edge of the blade.

According to the present invention, even if the impeller is rotated at a high speed, it is possible to sufficiently suppress the occurrence of excessive stress on the entire back surface of the hub, so both improvement of the impeller performance and improvement of the durability of the impeller are achieved. Can be achieved.

It is a side view of the turbine impeller concerning the embodiment of the present invention, and a part is fractured. It is an enlarged view of the arrow view part II in FIG. 1 is a side sectional view of a turbocharger according to an embodiment of the present invention. FIG. 4A is a diagram showing a stress distribution in a part of a region excluding the balance adjustment portion on the rear surface of the turbine hub according to the new knowledge, and FIG. 4B is a diagram at the rear surface of the turbine hub according to the new knowledge. It is a figure which shows the stress distribution of the one part area | region containing a balance adjustment site | part. It is side sectional drawing of a common turbine impeller, Comprising: A part is fractured | ruptured. It is side sectional drawing of the other common turbine impeller, Comprising: A part is fractured | ruptured. FIG. 7A is a diagram showing the stress distribution in a part of the region excluding the balance adjustment portion on the rear surface of the general turbine hub, and FIG. 7B shows the balance adjustment portion on the rear surface of the general turbine hub. It is a figure which shows the stress distribution of the one part area | region containing. FIG. 8A is a diagram showing the stress distribution in a part of the region other than the balance adjustment portion on the back surface of another general turbine hub, and FIG. 8B is a diagram on the back surface of another general turbine hub. It is a figure which shows the stress distribution of the one part area | region containing a balance adjustment site | part.

  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. 2 and 3, the turbocharger 1 according to the embodiment of the present invention supercharges the air supplied to the engine using the energy of the exhaust gas from the engine (not shown). is there. The specific configuration of the turbocharger 1 is as follows.

  The turbocharger 1 includes a bearing housing 3, and a plurality of bearings 5 are provided in the bearing housing 3. The plurality of bearings 5 have a rotor shaft (turbine shaft) extending in the front-rear direction. In other words, the rotor shaft 7 is rotatably provided in the bearing housing 3 via the bearing 5.

  A compressor housing 9 is provided on the front side (one side) of the bearing housing 3, and a compressor impeller 11 that rotates integrally with the rotor shaft 7 is provided in the compressor housing 9. The components of the compressor impeller 11 will be described. A compressor hub 13 is provided in the compressor housing 9, and the compressor hub 13 is connected to the rotor shaft 7 via a fixing nut 15. Further, the outer peripheral surface of the compressor hub 13 extends radially outward from the axial direction of the compressor hub 13 (in other words, radially outward from the axial direction of the compressor impeller 11). Further, a plurality of compressor blades 17 are provided on the outer peripheral surface of the compressor hub 13 at intervals in the circumferential direction.

  An air intake port 19 for taking in air is formed on the front side of the compressor housing 9 (in other words, the inlet side of the compressor impeller 11), and this air intake port 19 can be connected to an air cleaner (not shown). is there. An annular diffuser flow path 21 for boosting the compressed air is formed on the outlet side of the compressor impeller 11 between the bearing housing 3 and the compressor housing 9, and the diffuser flow path 21 is an air intake port. 19 is communicated. Further, a compressor scroll passage 23 is formed in the compressor housing 9 so as to surround the compressor impeller 11, and the compressor scroll passage 23 communicates with the diffuser passage 21. An air discharge port (not shown) for discharging the compressed air is formed at an appropriate position of the compressor housing 9, and this air discharge port communicates with the compressor scroll passage 23, and Can be connected to a cylinder (not shown).

  A turbine housing 25 is provided on the rear side (other side) of the bearing housing 3. A turbine impeller 27 that rotates using the energy of exhaust gas from a cylinder of the engine is provided in the turbine housing 25. The components of the turbine impeller 27 will be described. A turbine hub 29 is provided in the turbine housing 25, and the turbine hub 29 is integrated with the rear end portion (the other end portion) of the rotor shaft 7. It is connected. The outer peripheral surface of the turbine hub 29 extends radially outward from the axial direction of the turbine hub 29 (in other words, radially outward from the axial direction of the turbine impeller 27). On the side, a fixing nut 31 is provided. Further, a plurality of turbine blades 33 are provided on the outer peripheral surface of the turbine hub 29 at intervals in the circumferential direction.

  A gas intake (not shown) for taking in exhaust gas is formed at an appropriate position of the turbine housing 25, and this gas intake can be connected to a cylinder of the engine. A turbine scroll passage 35 is formed inside the turbine housing 25 so as to surround the turbine impeller 27, and the turbine scroll passage 35 communicates with the gas intake port. Further, a gas discharge port 37 for discharging exhaust gas is formed on the rear side of the turbine housing 25 (in other words, on the outlet side of the turbine impeller 27). The gas discharge port 37 is connected to the turbine scroll passage 35. And can be connected to an exhaust gas purification device (not shown).

  Next, the main part of the embodiment of the present invention will be described.

  A portion of the fixing nut 31 and a portion of the rear surface of the turbine hub 29 are subjected to cutting for balance adjustment (for balance correction) based on the result of the dynamic balance test of the turbine impeller 27. In FIG. 1, a portion (balance adjustment portion) FP subjected to balance adjustment cutting is indicated by an imaginary line.

  In the embodiment of the present invention, the shaft center of the turbine hub 29 (in other words, the shaft center of the turbine impeller 27) SC based on the above-described novel findings (see [Means for Solving the Problems]). The length t from a predetermined imaginary reference line VL to the rear surface of the turbine hub 29 in an arbitrary side cross section parallel to is increased in a step-like manner as it approaches the axis SC side of the turbine hub 29 (an aspect of a gradual increase) ). Here, the predetermined virtual reference line VL is a virtual line that passes through the proximal end of the radially outer edge (front edge) of the turbine blade 33 and is perpendicular to the axis of the turbine hub 29.

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

  When the exhaust gas taken into the turbine housing 25 from the gas inlet is supplied to the turbine impeller 27 side via the turbine scroll passage 35, the turbine impeller 27 can be rotated by the energy of the exhaust gas, and the compressor impeller 11 can be rotated in conjunction with the rotor shaft 7. Thereby, the air taken in from the air intake 19 to the compressor impeller 11 side can be compressed and discharged from the air discharge port via the diffuser flow path 21 and the compressor scroll flow path 23 and supplied to the engine cylinder. Can be supercharged (operation (I) of the turbocharger 1).

  In addition to the action (I) of the turbocharger 1, the length t from a predetermined virtual reference line VL to the rear surface of the turbine hub 29 in an arbitrary side cross section parallel to the axis SC of the turbine hub 29 is determined by the length of the turbine hub 29. Since it gradually increases as it approaches the axis SC side, applying the above-described new knowledge, even if the turbine impeller 27 is rotated at a high speed, the balance hub 29 including the balance adjustment part FP is included. It is possible to sufficiently suppress the occurrence of excessive stress on the entire rear surface (operation (II) of the turbocharger 1).

  Therefore, according to the embodiment of the present invention, even if the turbine impeller 27 is rotated at a high speed, it is possible to sufficiently suppress the occurrence of excessive stress on the entire rear surface of the turbine hub 29. It is possible to improve the durability of the turbine impeller 27 (in other words, improve the performance of the turbocharger 1 and improve the durability of the turbocharger 1).

(Modification)
As described above, the length t from the predetermined virtual reference line VL to the rear surface of the turbine hub 29 in an arbitrary side cross section parallel to the axis SC of the turbine hub 29 is close to the axis SC side of the turbine hub 29. In addition to grasping the invention according to the embodiment as the turbine impeller 27 that gradually increases in accordance with the turbine impeller 27, the turbine impeller 27 can be regarded as a method of adjusting the balance (balance correction).

  That is, the turbine impeller balance adjusting method (balance correcting method) according to the modification of the embodiment of the present invention is based on a turbine hub from a predetermined virtual reference line VL in an arbitrary side section parallel to the axis SC of the turbine hub 29. A part of the rear surface of the turbine hub 29 based on the result of the dynamic balance test of the turbine impeller 27 while satisfying the condition that the length t to the rear surface of the turbine 29 gradually increases as it approaches the axis SC side of the turbine hub 29. It is intended to perform cutting for balance adjustment (for balance correction).

  The turbine impeller balance adjustment method according to the modification of the embodiment of the present invention also exhibits the same operations and effects as the operation (II) and the effects of the above-described embodiment of the present invention.

  The present invention is not limited to the description of the above-described embodiment, and can be implemented in various other modes, for example, a configuration applied to the rear surface of the turbine hub 29 is applied to the rear surface of the compressor hub 13. is there. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

FP Balance adjustment part VL Reference line 1 Turbocharger 7 Rotor shaft 9 Compressor housing 11 Compressor impeller 13 Compressor hub 15 Fixing nut 17 Compressor blade 19 Air intake port 21 Diffuser passage 23 Compressor scroll passage 25 Turbine housing 27 Turbine impeller 29 Turbine hub 31 Fixing nut 33 Turbine blade 35 Turbine scroll passage 37 Gas outlet

Claims (2)

In an impeller used for a turbocharger and rotating using the energy of exhaust gas,
A hub whose outer peripheral surface extends radially outward from the axial direction, and a part of which is subjected to cutting for balance adjustment based on the result of a dynamic balance test;
A fixing nut which is provided at an end portion on the exhaust gas outflow side in the hub and which is subjected to cutting for balance adjustment based on a result of a dynamic balance test;
A plurality of blades that are provided on the outer peripheral surface of the hub at intervals in the circumferential direction, and whose leading edge is positioned radially outward from a portion of the maximum diameter on the outer peripheral surface of the hub ,
At any cross-sectional side view parallel to the axis of the hub, from the reference line vertical virtual base end of the leading edge to the axis of the street and the hub of the blade, the length to the back of the hub, the is adapted to increase stepwise in accordance with approaches toward the axis of the hub,
The balance-adjusted cutting part is a part of the outer peripheral edge of the fixing nut and a part of the outer peripheral edge of the part that increases stepwise on the back surface of the hub and is the maximum of the trailing edge of the blade. impeller, characterized in that than the site of the diameter of a portion located radially inwardly. In a method of balancing an impeller that is used in a turbocharger and that rotates using the energy of exhaust gas,
The front edge of the blade of the impeller is positioned radially outward from the maximum diameter portion on the outer peripheral surface of the hub of the impeller, and the front edge of the blade is in an arbitrary side cross section parallel to the axis of the hub. The length from an imaginary reference line passing through the base end and perpendicular to the hub axis to the rear surface of the hub increases stepwise as it approaches the axial center of the hub, and the rear surface of the hub A part of the hub and a part of the fixing nut provided at the end of the exhaust gas on the outflow side of the hub based on the result of the dynamic balance test of the impeller To the balance for cutting,
The balance-adjusted cutting part is a part of the outer peripheral edge of the fixing nut and a part of the outer peripheral edge of the part that increases stepwise on the back surface of the hub and is the maximum of the trailing edge of the blade. A method for adjusting the balance of an impeller, wherein the balance is a portion located radially inward of a diameter portion.

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