Turbocharger compressor with an elliptical diffuser wall

Abstract

A turbocharger (10) having a compressor housing (15) and a bearing housing (17). The compressor housing (15) including an elliptical shaped wall (16) extending between an air inlet (11) and a volute (13) formed by the compressor housing (15). The bearing housing (17) forms a flat bearing housing wall (14) opposing the compressor wall (16) wherein the compressor wall (16) and bearing housing wall (14) form an elliptical diffuser (12) between the air inlet (11) and the volute (13).

Claims

1. A turbocharger (10) comprising: a compressor housing (15) including: a compressor wall section (16) for housing a compressor wheel; a volute (13); a diffuser, wherein the diffuser has a diffuser compressor wall section extending between the compressor wall section (16) and the volute (13); a bearing housing (17) including a flat bearing housing wall (14) situated opposite to the diffuser compressor wall section; wherein a portion of the diffuser compressor wall section (16) has an elliptical shape with a major axis of the elliptical shape parallel to the flat bearing housing wall (14) and a minor axis perpendicular to the flat bearing housing wall (14).

2. The turbocharger according to claim 1, wherein the ratio of the major axis to the minor axis is within a range of 2:1 to 20:1.

3. The turbocharger according to claim 1, wherein the ratio of the major axis to the minor axis is within a range of 5:1 to 15:1.

4. The turbocharger according to claim 1, wherein the ratio of the major axis to the minor axis is within a range of 5:1 to 10:1.

5. The turbocharger according to claim 1, wherein the ratio of the major axis to the minor axis is within a range of 6:1 to 8:1.

6. The turbocharger according to claim 1, wherein the ratio of the major axis to the minor axis is 7:1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

(2) FIG. 1 shows a conventional turbocharger compressor housing having a straight diffuser wall section. It is not an illustration of the present invention;

(3) FIG. 2 shows a turbocharger compressor housing having a diffuser wall section with an elliptical shape and thus a gradual pinch. It is an illustration of the present invention. The compressor wheel and the turbine shaft are not shown, and

(4) FIG. 3 shows the major and minor axis of the ellipse defining the elliptical shape of the compressor housing diffuser wall section.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) FIG. 1 shows the compressor portion 1 of a conventional turbocharger. The compressor portion 1 has an air inlet 2, a compressor wheel 3, a straight diffuser 4, a volute 6, a bearing housing 7, and a compressor housing 8.

(6) FIG. 2 shows a compressor portion of a turbocharger 10 according to one embodiment of the invention. The compressor portion has an air inlet 11, an elliptical diffuser with a gradual pinch 12, a volute 13 a bearing housing having a straight, or flat, bearing housing diffuser wall 14, and a compressor housing 15. The compressor wheel and the turbine shaft are not shown. The elliptical diffuser 12 is formed by the compressor housing 15 which has an elliptical wall 16 and the flat wall of the bearing housing 14. The diffuser 12, therefore, has an elliptical wall and an opposing flat wall. As illustrated in FIG. 3, the major axis A.sub.major of the ellipse may be either close to parallel to the face of the bearing housing wall 14 or extend away from perpendicular to the bearing housing wall 14. The axes need not be exactly parallel or perpendicular to the bearing housing wall 14.

(7) The ratio of the major A.sub.major and minor A.sub.minor axes influences the shape and length of the diffuser 12. If the major axis A.sub.major of the ellipse is directed away from the face of the bearing housing wall 14 and if the major axis A.sub.major is much longer than the minor axis A.sub.minor, then the ellipse will be more pointed and the diffuser 12 will be curved and rather short. On the other hand, if the major A.sub.major and minor axes A.sub.minor are close in length the diffuser 12 will be less curved and longer. In this configuration a ratio of the major axis A.sub.major to the minor axis A.sub.minor of between 2:1 and 20:1 is generally appropriate.

(8) The performance of a turbocharger compressor may be assessed by measuring the optimum compressor pressure ratio, and the optimum compressor efficiency. Testing can be performed on a calibrated turbocharger performance gas stand, which, with few exceptions, is consistent with the Turbocharger Gas Stand Test CodeSAE J1826 and the SAE Turbocharger Nomenclature and TerminologySAE J922 Recommended Practice.

EXAMPLE 1

(9) A baseline turbocharger having a 71 mm diameter compressor wheel was constructed utilizing a conventional, straight diffuser and was gas stand performance tested. At a speed of 129,000 rpm, and a flow range between 0.22-0.33 kg/s, the turbocharger produced an average pressure ratio of 3.02 and a baseline efficiency curve. A second turbocharger was constructed and gas stand performance tested with a different compressor cover having an elliptical diffuser with an axis ratio of approximately 7:1. This second turbocharger, tested within the same speed and flow range, produced an average increase in pressure ratio over the baseline of 0.06 and an average increase in compressor efficiency of 2%.

(10) Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of 2:1 to 20:1 is intended to include any and all sub-ranges between and including the recited value of 2:1 and the recited value of 20:1.