CONNECTION DEVICE FOR A TURBOCHARGER, AND TURBOCHARGER

Abstract

A connection device for an exhaust gas turbocharger has an essentially bent first element and an essentially bent second element. The first element and the second element are detachably connected with each other in a first end region or in a second end region, respectively, and are movably connected with each other in a third end region or in a fourth end region, respectively. A first supporting portion extends between the first end region and the third end region and a second supporting portion extends between the second end region and the fourth end region. The connection device comprises a recess which is formed in the element for the reduction of stresses.

Claims

1.-8. (canceled)

9. A connection device for an exhaust gas turbocharger, comprising: an essentially bent first element (2); and an essentially bent second element (3), wherein the first element (2) and the second element (3) are detachably connected with each other in a first end region (6) or in a second end region (7), respectively, and are movably connected with each other in a third end region (17) or in a fourth end region (21), respectively, and wherein a first supporting portion (16) extends between the first end region (6) and the third end region (17) and a second supporting portion (19) extends between the second end region (7) and the fourth end region (21), and wherein the supporting portions (16, 19) are provided for accommodating casing sections of the exhaust gas turbocharger, and wherein the connection device (1) comprises a recess (27) which is formed in the element (2; 3) for the reduction of stresses, and wherein the recess (27) is formed like an elongated hole, having a width (B) which is smaller than a length of the recess, which extends over the circumference of the element (2, 3).

10. The connection device according to claim 9, wherein the recess (27) is formed in the supporting portion (16; 19).

11. The connection device according to claim 9, wherein the recess (27) is formed in a region which is subjected to high tensile and compressive stresses.

12. The connection device according to claim 9, wherein the supporting portion (16; 19) comprises three recesses (27).

13. The connection device according to claim 9, wherein the recess (27) is formed in a band (24) of the supporting portion (16; 19).

14. The connection device according to claim 13, wherein the recess (27) comprises a maximum width (Bmax) which exhibits a value which is not greater than that of a width (B) of the band (24).

15. The connection device according to claim 9, wherein the recess (27) is formed mainly rounded.

16. An exhaust gas turbocharger, comprising a first casing section and a second casing section, wherein the first casing section and the second casing section are connected with each other by the connection device as in claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 shows a perspective view of a connection device for an exhaust gas turbocharger.

[0020] FIG. 2 shows a cross-section of the connection device according to FIG. 1.

[0021] FIG. 3 shows a plan view of the connection device according to FIG. 1.

[0022] FIG. 4 shows in a plan view a cutout of the connection device in a first alternative exemplary embodiment.

[0023] FIG. 5 shows in a plan view a cutout of the connection device in a second alternative exemplary embodiment.

[0024] FIG. 6 shows in a plan view a cutout of the connection device in a third alternative exemplary embodiment.

DETAILED DESCRIPTION

[0025] An exhaust gas turbocharger (not shown in detail) comprises a first casing section as a flow-through exhaust gas guide portion which during operation of the exhaust gas turbocharger is flown through by a fluid, generally by exhaust gas. The exhaust gas is generally, but not necessarily, a combustion product of a combustion engine (not shown in detail).

[0026] A second casing section, which is formed as a bearing portion and serves to support a rotor assembly (not shown in detail) is associated with the exhaust gas turbocharger. The bearing portion is positioned between a flow-through air guide portion (not shown in detail) of the exhaust gas turbocharger and the exhaust gas guide portion.

[0027] The rotor assembly (not shown in detail) comprises a compressor wheel (not shown in detail) and a turbine wheel (not shown in detail), which are connected non-rotatably with each other via a shaft (not shown in detail). The compressor wheel is arranged in a compressor wheel chamber (not shown in detail) of the air guide portion to take in generally fresh air. The turbine wheel (not shown in detail) is rotatably accommodated in a wheel chamber (not shown in detail) of the exhaust gas guide portion.

[0028] During operation of the exhaust gas turbocharger, the turbine wheel is subjected to the exhaust gas flowing through the exhaust gas guide portion and driven by it so that it may perform a rotary movement. This rotary movement may be transferred to the compressor wheel via the shaft, which thereby simultaneously to the rotary movement of the turbine wheel may perform a rotary movement. By means of the compressor wheel and its rotary movement, fresh air is taken in which is compressed in the air guide portion.

[0029] The exhaust gas guide portion comprises a first flange surface at its end facing the bearing portion. A second flange surface of the bearing portion is formed opposite this first flange surface, wherein the two flange surfaces are formed mainly complementary.

[0030] The two flange surfaces are formed to extend both radially as well as in the circumferential direction relative to a longitudinal axis of the exhaust gas turbocharger, which corresponds to an axis of rotation of the turbine wheel. The exhaust gas guide portion comprises a first portion collar opposite the bearing portion, which is associated with an axially adjacent second portion collar of the bearing portion. The first flange surface and the second flange surface extend over the first portion collar and the second portion collar, respectively.

[0031] The exhaust gas guide portion and the bearing portion are connected with each other by a connection device 1 in the region of the flange surfaces. The connection device 1 comprises a first element 2 which is mainly bent in the circumferential direction and a second element 3 which is mainly bent in the circumferential direction, which on one end are detachably connected with each other by means of a first connecting element 4 and on the other end are movably connected with each other by means of a second connecting element 5, see FIG. 1 which illustrates the connection device 1 in a perspective view. The connection device 1 is basically formed similar to a pipe clamp connection. In other words, for the connection of the two casing sections a band-shaped connection device 1 is provided which at least partially encompasses the circumference of the first portion collar and the second portion collar in the radial, in the axial and in the circumferential direction.

[0032] A first end region 6 of the first element 2 and a second end region 7 of the second element 3 are configured for making a connection by means of the first connecting element 4 which is formed as a screw-nut element and, for this purpose, comprise a first clamping arm 8 and a second clamping arm 9, respectively. In the clamping arms 8, 9 each an opening 10 is formed through which the first connecting element 4, the screw, may be inserted. A head 11 of the first connecting element 4 is formed to rest on the first clamping arm 8. At the element end 12 facing away from the head 11, a clamping disk 13 and a safety element 14, in the present exemplary embodiment in the form of a nut, are arranged, so that the two elements 2, 3 may be clamped together through a preload force of the first connecting element 4.

[0033] The first element 2 extends starting from the first clamping arm 8 with a first stop 15, over a first supporting portion 16 to a third end region 17 which comprises a first eye-shaped safety element 18. The second element 3 is formed identically and extends starting from the second clamping arm 9 over a second supporting portion 19 to a second eye-shaped safety element 20 in a fourth end region 21. The second clamping arm 9 comprises a second stop 22 at its second end region 7 which faces away from the second safety element 20.

[0034] In order to obtain a relative adaptation of an inner circumference 23 of the connection device 1 to an outer circumference of the portion collars the two elements 2, 3 are made from a profiled material with legs 25 formed between a band 24, which comprises an essentially U-shaped or V-shaped profile. The profile could also be referred to as a trapezoidal profile.

[0035] FIG. 2 shows the connection device 1 in a cross-section. The places 26 marked by an arrow identify places where tensile and compressive stresses occur during operation, wherein the places 26, in particular in the third end region 17 and in the fourth end region 21, are places with heavy material reshaping.

[0036] For reducing these tensile and compressive stresses, the first supporting portion 16 and the second supporting portion 19 comprise recesses 27. The recesses 27 are formed near the places 26, wherein also a portion region 28 of the supporting portions 16, 19, which in particular during installation is subjected to tensile stress, comprises recesses 27. In the present exemplary embodiment the recess 27 formed in the portion region 28 is arranged centrally between the two recesses in the region of place 26. This means that the element 2; 3 preferably comprises three recesses 27.

[0037] Ideally, the places of the tensile and compressive stresses are determined simulatively by means of computational programs, so that the positioning of the recesses 27 brings about a reduction or elimination of the compressive and tensile stresses.

[0038] FIGS. 4 to 6 show different shapes of the recesses 27. The choice of a suitable shape of the recess 27 depends on the occurring stresses or the stresses to be expected as well as on the selected material of the elements 2, 3. Another dependency is inherent in the constructive design of the connecting elements 4, 5.

[0039] As may be seen in particular in FIG. 3, in a plan view of the connection device 1, the selected shape of the recess 27 here is an elongated hole. Preferably, sharp edges of the recess 27 are to be avoided, because these may cause cracking.

[0040] The recesses 27 are formed in such a manner that they completely penetrate the thickness D of the band 24. In order to avoid a reduction in strength of the supporting portions 16, 19, the recesses 27 are portionwise formed at these. Preferably, they are formed to be symmetrically to a band center 29, wherein their maximum width Bmax does not exceed half a band width B. Exceeding half the band width B could lead to weakening, i.e. to a reduction of a section modulus of a cross-section comprising the recess 27 of the corresponding supporting portion 16; 19, which might in particular result in an expansion and thus loosening of the connection device 1 due to increased temperatures.

[0041] When positioning the recesses 27, the arrangement of the connection device 1 relative to the casing sections has also to be taken into consideration. A more pronounced thermal expansion is to be expected on the side facing the exhaust gas guide portion of the connection device 1, compared to the side facing the bearing portion of the connection device 1.