MXPA00001246A - Turbocharger integrated bearing system - Google Patents

Abstract

An integrated bearing system with journal and thrust bearings is incorporated in a single unit (6) centrally pinned to the bearing housing and having integral thrust surface lubrication grooves (40) and journal surface lubrication grooves (38) in combination with turbine and compressor wheel thrust surfaces. The bearing employs a first aperture (32) substantially equidistant from the ends to engage the locating pin (18) to prevent rotation of the bearing within the bearing case bore, while allowing the bearing to be free to symmetrically wobble within the bearing case bore.

Description

INTEGRATED TURBOCARGER BEARING SYSTEM CROSS REFERENCE TO RELATED REQUESTS This application claims the benefit of the filing date of the provisional application 60 / 054,908 that has the filing date on August 6, 1997 entitled Integral .Bearing Turbocharger (Integral Turbocharger Bearing ). BACKGROUND OF THE INVENTION Field of the invention: This invention relates generally to bearings for turbochargers. More particularly, the invention offers an integrated bearing system with journal and thrust bearings incorporated in a single unit centrally interlocked on the bearing frame and having a thrust surface and groove surface lubrication grooves integrated in combination with surfaces of compressor wheel and turbine thrust. Description of the Related Art Exhaust gas-driven turbochargers include a rotary shaft carrying a turbine wheel and a compressor wheel, rotatably supported within a center frame by oil-lubricated bearings. The turbine wheel is driven by the exhaust gas at high speeds of rotation, frequently exceeding 100,000 revolutions per minute, in order to drive the compressor wheel to provide charge air under pressure for use by a machine. internal combustion. The axial movement of the axle and the wheels must be resisted by the bearing system and the dynamic characteristics of rotation of the rotor group must be received and cushioned by the action of the journal of the bearing system. The prior art systems typically employ a pair of trunnion bearings limited separately or spaced apart by a central spacer, in order to achieve desired dynamic rotation characteristics. Thrust loads are absorbed through thrust washers or collars and flange designs or end plates, an element of which can be integrated with one of the trunnion bearings. Accordingly, it is desirable to offer a bearing system that employs the least possible number of parts for simplicity. It is also desirable that the number of corresponding surfaces be reduced in the bearing system in order to improve normality and ease of balance. It is further desirable that the bearing maintain angular flexibility to allow movement of the shaft while providing adequate damping. It is further desirable that the bearing include an integral pressure powered lubrication capability for the thrust and stump surfaces.

SUMMARY OF THE INVENTION An integrated bearing system for a turbocharger employing the present invention incorporates a center frame that includes a bearing cover bore and a protrusion with an opening that receives a locating pin extending into the cover bore. bearing substantially centrally in the bore. The single-piece bearing is received in the bearing shell bore and has integral thrust surfaces at opposite ends and integral bearing surfaces at bearing portions near the ends. The bearing further includes an internal bore for receiving an axle extending between a compressor wheel and a turbine wheel, the internal bore having a plurality of axial grooves extending between the thrust surfaces. The bearing further includes a first aperture substantially equidistant from the ends and which engages the locating pin to indicate rotation of the bearing within the bearing cover bore. This arrangement allows the bearing to oscillate symmetrically within the bore of the bearing cover. The bearing further has a second opening located substantially centrally and in communication with a lubrication oil channel which penetrates the bearing cover bore in the center frame.

Thrust impellers on an end surface of a hub in each of the compressor wheel and turbine wheel engage the thrust surfaces of the bearing. BRIEF DESCRIPTION OF THE DRAWINGS The details and features of the present invention will be understood more clearly in relation to the detailed description and the drawings in which: Figure 1 is a side section view of a turbocharger incorporating a first embodiment of the system of the present invention with direct contact between the thrust surface of the integral bearing and the hub of the compressor wheel; Figure Ib is a side sectional view of a turbocharger incorporating a second embodiment of the present invention employing a thrust washer; Figure 2 is a detail of an upper section of the thrust bearing and integral stump unit; Figure 3a is an end view of the integral thrust and bearing bearing unit; Figure 3b is the end view of Figure 3 with geometric relation of the defined elements; Figure 3c is a detail of a partial view of the radial grooves in the thrust surface; Figure 3d is a detail of a partial view of a 3d line in Figure 2; Figure 4 is a section through line 4-4 of Figure 2; Figure 5 is a detailed section of the pushing face of the unit, through line 5-5 of Figure 3b, detailing steps, ramps, and flat surfaces in the lubrication system; Figure 6 is a sectional view of the compressor wheel used in the invention detailing the oil seal, the thrust surface and the coating; and Figure 7 is a detail of a partial sectional view of the line 7-7 in Figure 6. DETAILED DESCRIPTION OF THE INVENTION With reference to the drawings, a turbocharger incorporating the present invention is illustrated in the figure. A turbine frame 1, a center frame 2 and a compressor frame 3 form the cover of the turbocharger. A turbine wheel and a shaft assembly 4 are fixed on a compressor wheel 5, the shaft rotatably supported in a bearing 6 carried in the center frame. Piston ring seals 7 in the turbine wheel hubs and compressor wheel prevent lubrication oil leaks from the center frame in the turbine or compressor frames. A compression ring 8 increases the seal fixation of the compressor frame on the center frame. A ring 10 is engaged between the turbine frame and the center frame extending behind the turbine wheel as a thermal barrier. Bolts 11 extend through the washer clamps 12 and fix the turbine frame on the center frame while bolts 13 and washer clamps 14 fix the compressor frame on the center frame. The bearing 6 is limited in its rotation in the bearing cover hole 16 of the center frame by a pin 18 inserted through an opening 20 in a protrusion 22. The bearing is semiflotated with symmetrical freedom of end movement a end due to the centrally located pin thus optimizing the effectiveness of the oil film cushion in the clearance between the bearing outer diameter and the cover bore. Lubrication for the bearing is supplied through an inlet 24. The shaft extending through the bearing includes a recessed portion 26 that promotes oil flow between the shaft and the bearing. A detailed cross section of the bearing is illustrated in Figure 2. The thrust surfaces 28 and 30 are located at opposite ends of the bearing. The unitary bearing structure offers the minimum number of parts and causes a maximum parallelism of the thrust surfaces during the oscillating action of the bearing. The central location of the opening 32, which receives the locating pin, allows a uniform damping action of the bearing ends. The bore 34 of the bearing extends between the thrust surfaces and incorporates end portions 36 characterized by an improved surface finish for the bearing bracket of the non-recessed portions of the shaft. Axial grooves 38 extend longitudinally along the perforation surface for lubricant flow. The axial grooves also provide an improvement in the dynamic characteristics of the rotor by improving the resistance to the movement of the subsynchronous shaft through the reduction of the oil whirl which is in bearing conditions with light load. The bearing in accordance with that illustrated in the embodiment presented employs a lubrication system of feeding under pressure. The thrust surfaces of the bearing for a current production mode, as best seen in FIGS. 3 a-d, incorporates a plurality of radial slots 40 that provide improved thrust while improving control of contamination. For the embodiment illustrated in the drawings, eight spline radial slots at 45 ° (Figure 3b) are used with four of the slots in alignment with the axial slots in the bearing bore, as best seen in Figure 3c. The detail of the form V of the slots used in this modality appears in figure 3d. The slots have a V-shape at 90 ° with a depth between 0.15 and 0.25 mm. A radius in vertex is provided. A recess 42 in the inner periphery of each thrust surface further improves the delivery and distribution of oil. A cut in end view of the bearing illustrated in Figure 4 shows the pin opening 32 and the lubrication opening 44. Figure 5 shows the outline for both thrust surfaces in the bearing in the form of a cut through the line 5-5 of Figure 3b. In the relative direction of rotation of the compressor wheel and turbine wheel relative to the thrust surfaces, the radial grooves are followed by a lower plane 46 which is a transition to a ramp 48 ending at a higher level 50. For the current production mode illustrated in the drawings, a ramp length of approximately 1.55 mm employs an elevation of .025 to .051 mm between the lower plane and the upper level. A thrust surface of the bearing engages a thrust impeller in the turbine wheel hub as shown in Figures la and Ib. A compressor wheel used in combination with the described bearing is shown in detail in figure 6. The wheel 5 includes a seal ring slot 52 and a thrust surface 54 integrated in the hub 56. The direct incorporation of the surface Push on the wheel hub reduces the number of corresponding surfaces which improves the normality and ease of balance as well as improves heat transfer from the thrust surfaces. In the case of the illustrated embodiment, a hard anodization is employed in the compressor wheel to improve the wear resistance of seal ring and thrust in the hub. A Nituff coating produced by Ni et Industries, Inc. 2424 N. Foundation Drive, South Bend, Indiana offers a suitable surface. To facilitate processing, the outer surfaces of the wheel are covered, however, the shaft bore is not coated. As shown in FIG. 7, a chamfer 58 at the outlet of the bore towards the thrust surface is used for the transition of the lining in order to avoid a positive projection of coating buildup on the thrust surface due to the masking of the lining. the perforation during processing. The compressor wheel employed incorporates a threaded portion 60 in the nose of the perforation for its fixation on the shaft 62 which minimizes the hanging weight in the bearing. In addition, an overall reduction of the hanging distance from the bearing journal to the center of mass of the wheel is offered by the design of the bearing system embodying the present invention. A reduced overhang reduces the compressor end deviation and improves the relative location of the bearing cushion. A second embodiment of the invention appears in Figure Ib where a thrust washer 64 is included between the bearing thrust surface and the compressor wheel hub. The washer accommodates thrust loads with a greater wear tolerance. The use of a washer and not of a conventional thrust collar offers a simple fabrication geometry where the required surface finish and parallelism are more easily maintained. Having described the present invention with details in accordance with what is required by the patent statutes, experts in the field will recognize that modifications and substitutions can be made to the specific modalities presented here. Such modifications and substitution are within the scope of the present invention in accordance with that defined in the appended claims.

Claims (1)

1. CLAIMS An integrated bearing system for a turbocharger, comprising: a central frame including a bearing cover bore and a protrusion with an opening receiving a locating pin extending into the bearing bore bore substantially centrally in the bore; a one-piece bearing received in the bearing cover bore and having integral thrust surfaces at opposite ends and integral bearing surfaces at bearing portions near the ends, said bearing further having an internal bore for receiving a axis extending between a compressor wheel and a turbine wheel, the internal bore has a plurality of axial grooves extending between the thrust surfaces, said bearing has a first opening substantially equidistant from the ends and which engages the locating pin to prevent rotation of the bearing within the bearing cover bore, said bearing can oscillate symmetrically within the bearing bore bore, said bearing further having a second substantially central opening and in communication with a penetrating lubrication oil channel in the drilling of cushion cover ete in the center frame; and thrust drivers on an end surface of a hub in each of the compressor wheel and turbine wheel, said thrust drivers engage the thrust surfaces of the bearing. An integrated bearing system for a turbocharger as defined in claim 1 wherein each thrust surface incorporates a plurality of radial grooves extending from the internal bore, at least one of said grooves being aligned with one of said grooves axial in the internal perforation. An integrated bearing system for a turbocharger as defined in claim 2 wherein the thrust surface incorporates a recess surrounding the internal bore from the axial grooves to the radial grooves. An integrated bearing system for a turbocharger as defined in claim 2 wherein the thrust surface is circumferentially profiled with a lower plane substantially adjacent to each radial slot that is a transition to a ramp that terminates at a flat upper part adjacent to the next radial groove. An integrated bearing system for a turbocharger as defined in claim 1 wherein the shaft includes a central portion having a reduced diameter to promote lubricant flow in the bearing. An integrated bearing system for a turbocharger as defined in claim 1 wherein the outer diameter of the bearing has a recess between the trunnion surface portions and a central protruding portion including the first opening and the second opening. An integrated bearing system for a turbocharger as defined in claim 1 wherein the compressor wheel incorporates an integral hub having a thrust surface for engaging one of the thrust surfaces in the bearing. An integrated bearing system for a turbocharger as defined in claim 7 wherein the integral hub of the compressor wheel further incorporates a piston ring groove and the bearing system further comprises a piston ring mounted in the groove of the piston ring. piston ring and hooks the center frame in the form of a seal. An integrated bearing system for a turbocharger as defined in claim 7 further comprising an anodized coating on the bucket thrust surface. An integrated bearing system for a turbocharger as defined in claim 9 wherein the anodized coating is Nituff.