KR-102961505-B1 - How to balance the turbine wheel of an exhaust gas turbine and a balanced turbine wheel

KR102961505B1KR 102961505 B1KR102961505 B1KR 102961505B1KR-102961505-B1

Abstract

The present invention describes a method for balancing a turbine wheel (10) of an exhaust gas turbine and a balanced turbine wheel (10). The exhaust gas turbine wheel has a hub rear wall (15) facing away from the fluid flow area and having a depression (13) and a marking collar (16) created by the removal of material.

Inventors

가이스트 니코
젠 슈테판
부르거 프랑크

Assignees

액셀러론 스위츠랜드 엘티디

Dates

Publication Date: 20260508
Application Date: 20220518
Priority Date: 20210518

Claims (17)

A method for balancing a turbine wheel (10) for an exhaust gas turbine, wherein the turbine wheel (10) can be rotated about its rotation axis (11) and has a hub (12) and a plurality of turbine blades attached to the hub (12) and arranged within a fluid flow region (14), and the hub has a rear wall (15) of the hub having a marking bead (16) facing away from the fluid flow region (14) and extending concentrically about the rotation axis (11). The above method is: - A step of moving an elliptical material-removal tool relative to the turbine wheel (10) at a mass-removal position next to the marking bead (16); A method for balancing a turbine wheel (10) for an exhaust gas turbine, comprising the step of creating a mass-removal recess (13) asymmetric with respect to the rotation axis (11) within the hub rear wall (15) to balance the turbine wheel (10) by removing the hub material of the hub rear wall (15) next to the marking bead (16) with the above material-removal tool and leaving the marking bead (16) intact.
In paragraph 1, A method for balancing a turbine wheel (10) for an exhaust gas turbine, wherein the above material-removal tool is a grinding tool having an elliptical grinding head.
In paragraph 1, A method for balancing a turbine wheel (10) for an exhaust gas turbine, wherein the above material-removal tool is a spherical grinding tool having a spherical grinding head.
In paragraph 1, A method for balancing a turbine wheel (10) for an exhaust gas turbine, wherein the above mass-removal recess (13) is formed along a ring segment in a circumferential direction around the rotation axis (11).
In paragraph 1, - A step of determining the imbalance of the turbine wheel; - A step of setting a material-removal profile for the mass-removal depression (13) according to the above-determined imbalance; and - A method for balancing a turbine wheel (10) for an exhaust gas turbine, further comprising the step of creating the mass-removal depression (13) with the material-removal profile set above.
In paragraph 1, - A step for defining the hub test geometry without removal; and - Further includes the step of calculating a first hub quality parameter by using the maximum removal hub test geometry, obtained by subtracting the maximum removal amount from the hub rear wall of the hub test geometry without removal, as the above-defined hub test geometry without removal, and A method for balancing a turbine wheel (10) for an exhaust gas turbine, wherein the removal of the hub material from the rear wall (15) of the hub is limited by the maximum amount of removal.
In paragraph 6, A method for balancing a turbine wheel (10) for an exhaust gas turbine, further comprising the step of optimizing the hub geometry by optimizing the hub optimization variable calculated using the first hub quality parameter by repeatedly changing the hub test geometry between the hub test geometry without removal and the hub test geometry with maximum removal.
In paragraph 6, A method for balancing a turbine wheel (10) for an exhaust gas turbine, wherein the above hub quality parameters include at least one parameter selected from the following list: mechanical stress, mechanical cycle optimization variables, and cycle fatigue indicators.
In Paragraph 7, A method for balancing a turbine wheel (10) for an exhaust gas turbine, wherein the above hub quality parameters include at least one parameter selected from the following list: mechanical stress, mechanical cycle optimization variables, and cycle fatigue indicators.
In paragraph 6, A method for balancing a turbine wheel (10) for an exhaust gas turbine, further comprising the step of calculating a second hub quality parameter using the specified hub test geometry without removing the hub rear wall material from the hub test geometry.
In Paragraph 10, A method for balancing a turbine wheel (10) for an exhaust gas turbine, further comprising the step of optimizing the hub geometry by optimizing the hub optimization variable calculated using first and second hub quality parameters by repeatedly changing the hub test geometry between a hub test geometry without removal and a hub test geometry with maximum removal.
A turbine wheel (10) for an exhaust gas turbine, and the turbine wheel (10) can be rotated around its rotation axis (11). - Hub (12); and - It has a plurality of turbine blades attached to the hub (12) and arranged within the fluid flow region (14), and the hub has a hub rear wall (15) facing away from the fluid flow region (14). In order to balance the turbine wheel (10), an asymmetric mass-removal recess (13) with respect to the rotation axis (11) is provided within the hub rear wall (15), and The above mass-removal recess (13) is configured as a concave depression within the hub rear wall (15) having a cross-sectional contour in the shape of an elliptical segment, and the cross-sectional contour of the mass-removal recess (13) is formed within a cross-sectional plane (ZZ) including the rotation axis (11). The hub rear wall (15) also has a marking bead (16) that extends concentrically with respect to the rotation axis (11), and the marking bead (16) and the mass-removal recess (13) are adjacent to each other and do not overlap radially, in a turbine wheel (10).
In Paragraph 12, The above mass-removal depression (13) has the following characteristics (a) to (g): (a) The cross-sectional contour of the above-mentioned mass-removal depression (13) has the shape of a circular segment; (b) The cross-sectional contour of the mass-removal recess (13) has a minimum radius of curvature greater than 0.03*F, where F is the diameter of the rear wall of the turbine wheel (10); (c) A cross-sectional contour of the mass-removal recess (13) satisfies the condition (((B*B)/H)/F ≥ 0.03), wherein H is the large half-axis of the elliptical cross-sectional contour of the mass-removal recess (13), B is the small half-axis of the elliptical cross-sectional contour of the mass-removal recess (13), and F is the diameter of the rear wall of the turbine wheel (10); (d) The mass-removal depression (13) is at least partially arranged within the radially outer half of the hub rear wall (15); (e) The characteristic that the above mass-removal depression (13) is created by a material-removal tool; (f) The mass-removal depression (13) has the characteristic of extending along a ring segment that extends circumferentially around the axis; (g) The mass-removal indentation (13) extends as a continuous line, as a sequence of parts of a continuous line, or as a sequence of intermittent spot indentations. A turbine wheel (10) having at least one of the following.
In Paragraph 12, The above marking bead (16) has the following characteristics (i) to (iv): (i) The marking bead (16) has a raised and convex characteristic within the cross-sectional plane; (ii) The marking bead (16) has a rotationally symmetric characteristic with respect to the rotation axis (11); (iii) The marking bead (16) is arranged according to the inequality (E ≤ (F - G)/2 and/or G/F > 0.5), wherein A is the radial range of the mass-removal recess (13) from the radial inner end of the mass-removal recess (13) to the radial outer end of the mass-removal recess (13), D is the radial distance from the mass-removal recess (13) to the apex of the marking bead (16), E = A + D is the radial distance from the radial outer limit of the mass-removal recess (13) to the apex of the marking bead (16), F is the diameter of the turbine wheel (10), and G is the diameter of the circle formed by the apex of the marking bead (16); (iv) The characteristic that the marking beads (16) are arranged radially inward of the mass-removal depression (13). A turbine wheel (10) having at least one of the following.
In Paragraph 12, The turbine wheel (10) is a radial turbine wheel for a radial exhaust gas turbine, or a mixed-flow turbine wheel for a mixed-flow exhaust gas turbine.
An exhaust gas turbine having a turbine wheel (10) as claimed in paragraph 12.
An exhaust gas turbocharger having a turbine wheel (10) as claimed in paragraph 12.

Description

How to balance the turbine wheel of an exhaust gas turbine and a balanced turbine wheel The present disclosure relates to a method for balancing a turbine wheel of an exhaust gas turbine by creating a mass-removal region of a defined shape and location within the rear wall of the hub of the turbine wheel of the exhaust gas turbine, and to a balanced turbine wheel for an exhaust gas turbine. Exhaust gas turbines are used to utilize energy within exhaust gases. To extract energy from the exhaust gas stream, a turbine wheel of the exhaust gas turbine is used, positioned within the exhaust gas stream and having a hydro-mechanically optimized shape. The turbine wheel is mounted here so as to be rotatably rotated around an axis of rotation. Due to the high rotational speed of the turbine wheel of an exhaust gas turbine and its location within the exhaust gas tract, the turbine wheel is a component of the exhaust gas turbine subjected to large thermal and mechanical loads. Above all, the mechanical load within the turbine wheel of an exhaust gas turbine is very large and is mostly caused by the high rotational speed and the associated centrifugal force. Deviations in the mass distribution along the circumference of the turbine wheel, which can impair the circularity of the turbine wheel and potentially generate additional loads, play a significant role here. Accordingly, both structural means and subsequent processing of the turbine wheel of the exhaust gas turbine actively address the mass unevenly distributed along the circumference, known as imbalance. In the prior art, to reduce imbalance in the turbine wheel of an exhaust gas turbine, a balancing rim is generally provided on the rear wall of the hub. The balancing rim takes the form of a convex bead extending circumferentially from the rear wall of the hub. During the balancing process, the balancing rim can be removed in a prescribed manner, thereby achieving a uniform mass distribution circumferentially in the turbine wheel of the exhaust gas turbine. Here, it is known that the balancing rim is removed using a flat grinding process. However, the balancing rims provided for the balancing process have disadvantages in many respects. These include, but are not limited to, providing, designing, and calculating additional components (and consequently mass) within the turbine wheel of the exhaust gas turbine, additional processing steps required in the production process, and the negative impact on the internal load distribution and stress of the turbine wheel of the exhaust gas turbine. Applying additional mass to the turbine wheel of a high-speed rotating exhaust gas turbine, which generates additional centrifugal force and adverse characteristics of the balancing rim, is detrimental to the mechanical stress within the turbine wheel of the exhaust gas turbine. Consequently, the balancing rim also has an adverse effect on cycling capacity, and specifically on cycling capacity related to low-cycle fatigue, also known here as low-cycle capacity. Considering the foregoing, there is a need for a method of balancing a turbine wheel of an exhaust gas turbine and a corresponding balanced turbine wheel that can at least partially reduce the foregoing disadvantages. US 2020/392 848 A1 describes an exhaust gas turbocharger wheel having a hub having a lug, a rear disc having a shaft connection part, a rotating shaft, and blades extending from the hub to form an exhaust gas flow channel. US 8 936 439 B3 describes a turbine wheel, wherein the turbine wheel is arranged around a shaft and has a rear side with a separator arranged above it, an inner undercut arranged between the separator and the shaft, and an outer undercut between the separator assigned to the rear side and the outer circumference. The present invention will be described in more detail below with reference to embodiments that do not limit the scope of protection defined by the claims. The attached drawings serve to illustrate embodiments and, together with the detailed description, explain the principles of the present invention. The elements of the drawings are relative to one another and are not necessarily at actual scale. Identical reference numerals indicate similar components. FIG. 1 shows a top view of the rear wall (15) of the hub of the turbine wheel (10) of an exhaust gas turbine according to one embodiment. FIG. 2 illustrates a radial cross-section along the cross-sectional plane (ZZ) of the turbine wheel (10) of FIG. 1. Figure 3 shows a radial cross-section as in Figure 2, along with the geometric dimensions of individual (partial) components. Figure 4 shows a detailed view of the cross-section of Figure 2. FIG. 5 illustrates a radial cross-section along the cross-sectional plane (ZZ) of a turbine wheel (10) during the execution of a method according to one embodiment of the present invention. With reference to FIGS. 1 to 4, a turbine wheel (10) of an exhaust gas turbine according to one embodimen