Speed sensor insert with bearing spacer indexing for a turbocharger

Abstract

A number of variations may include a turbocharger bearing housing comprising a bearing bore, a rolling element bearing assembly including an inner race and an outer race having a plurality of ball bearings disposed therebetween, wherein the rolling element bearing assembly is disposed within the bearing bore, a shaft for rotating the rolling element bearing assembly, located and supported within the inner race, a tubular bearing spacer, having at least one radial opening, positioned within the bearing bore, a mounting bore, a generally tubular insert mounted in the mounting bore and extending into the at least one radial opening of the tubular bearing spacer, and a rotational speed sensor mounted to the tubular insert via threaded fitting or friction fit.

Claims

1. A turbocharger bearing housing, including a bearing bore, a rolling element bearing assembly including an inner race and an outer race having a plurality of ball bearings disposed therebetween, wherein the rolling element bearing assembly is disposed within the bearing bore, a shaft for rotating the rolling element bearing assembly, located and supported within the inner race, a tubular bearing spacer, having at least one radial opening, positioned within the bearing bore, a mounting bore, a generally tubular insert mounted in the mounting bore and extending into the at least one radial opening in the tubular bearing spacer, and a rotational speed sensor mounted to the tubular insert via threaded fitting or friction fit.

2. The turbocharger as in claim 1, wherein the generally tubular insert is mounted in the mounting bore by a screw fit, a friction fit, a pressed fit or by bonding, staking, or welding.

3. The turbocharger as in claim 1, wherein the tubular insert and speed sensor are provided with indexing features for setting the depth of penetration of the speed sensor.

4. The turbocharger as in claim 1, wherein the insert has internal threading and external threading.

5. The turbocharger as in claim 1, wherein the bearing housing has an outer surface, the tubular insert includes a segment projecting outwards beyond the outer surface of the bearing housing, and wherein said projecting segment includes features for engagement of said insert for rotation.

6. The turbocharger as in claim 5, wherein said features for engagement of said insert for rotation comprise one or more flat surfaces.

7. The turbocharger as in claim 6, wherein said flat surfaces form a hexagon.

8. The turbocharger of claim 1, wherein said outer race includes an outer race window wherein a first axial end of the tubular insert is disposed within said outer race window thereby maintaining the outer race in alignment with an axis of the rotational speed sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is illustrated by way of example and not limitation in the accompanying drawings in which like reference numbers indicate similar parts, and in which:

(2) FIG. 1 depicts the section for a typical floating bearing turbocharger;

(3) FIG. 2 depicts a, through section “S-S” of FIG. 1 of a typical turbocharger;

(4) FIG. 3 depicts a magnified view of FIG. 2;

(5) FIG. 4 depicts a magnified view of the inventive insert;

(6) FIG. 5 depicts a magnified view of a variation on the inventive insert; and

(7) FIG. 6 depicts a magnified view of the second embodiment to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(8) To solve the problem of the journal bearing spacer rotating while the speed sensor is removed for service or replacement, the inventor generated a design of an insert which allows for the removal of the speed sensor while maintaining alignment of the spacer, thus allowing the speed sensor to be re-inserted through the spacer. Another advantage of the invention is that the insert prevents the spacer from wearing and damaging the outside of the sensor probe which would otherwise be caused by the fluctuating torque transmitted from the shaft to the bearing spacer during normal turbocharger operation. Accordingly, the durability of the speed sensor is improved, and the rate of failure, and the need for replacement, is reduced.

(9) In a first embodiment of the invention, as depicted in FIG. 4, an insert (80) is screwed into the bearing housing (20) to provide a mount for the speed sensor (70). The insert (80) has a feature (85), such as a hex or flats, so that it can be rotated to be screwed into the bearing housing (20). The insert has an externally facing thread (82) which can be threaded into an internally facing complementary thread (22) in the bearing housing (20). In the preferred mode of the invention, the insert (80) is sealed to the bearing housing (20) by an “O” ring or other suitable means such as tapered threads (86), and the depth of the nose of the insert in the bearing housing (i.e. the distance from the shaft (11) axis) is controlled by the distance from the inward facing surface (87) of the nut or locating feature to the inner end of the insert (80). The inward facing surface (87) of the nut or locating feature is axially constrained by an abutment on the bearing housing (20). The sensor (70) has an externally facing thread (71) which can be threaded into an internally facing thread (21) in the insert.

(10) When the sensor is threaded into the insert, a flange (76) on the sensor abuts against an indexing surface on the insert, thus setting the depth of the sensor in the insert. As explained above, the depth of the insert (in the bearing housing) is set in a similar method with the inwards facing surface (87) of the insert abutting against an outwards facing surface of the bearing housing. Thus the resultant air gap between the end (73) of the sensor and the rotating shaft (11) is set.

(11) The lower end of the tubular part (84) of the insert locates in the window (68) of the spacer (67). When the sensor is removed, the insert remains in place, thus keeping the spacer window aligned with the axis of the sensor position so that the sensor can be re-inserted into its correctly operating position.

(12) In a second embodiment of the invention, as depicted in FIG. 6, for sensing the speed of the rotating assembly in turbochargers equipped with rolling element bearings (REB), the outside diameter of the inner race is equipped with a flat for the purpose of creating a cyclic signal for sensing the rotational speed of the inner race and thus the rotating assembly. In the case in which the inner race is axially split onto two pieces, the flat can be on either inner race piece as long as the sensor axis is axially aligned with the axis of the center of the flat so that the sensor can read a cyclic signal.

(13) In the second embodiment of the invention, the shaft (11) for the rotating assembly is supported and located in an inner race (102) of an REB assembly. The REB assembly (or cartridge) is located within a bore (23) in the bearing housing (20). Typically, the outside diameter of the outer race (101), or in some cases the outside diameter of a cartridge, which contains the outer race (101), is supported by an oil film for the purposes of damping the REB assembly. With no metal to metal contact between the outer surface of the outer race (or cartridge) and the bore (23) in the bearing housing, the outer race is completely unconstrained angularly and axially and is partially constrained radially. The inventor saw the opportunity to provide both axial and angular constraint to the REB outer race (or cartridge) while providing a mount for the speed sensor.

(14) An insert (80) is screwed into the bearing housing (20) to provide a mount for the speed sensor (70). The insert (80) has a feature (85) such as a hex or flats so that it can be rotated to be screwed into the bearing housing (20). The insert has an externally facing thread (82) which can be threaded into an internally facing complementary thread (22) in the bearing housing (20). In the preferred mode of the invention, the insert (80) is sealed to the bearing housing (20) by an “O” ring (86), and the depth of the nose of the insert in the bearing housing (i.e. the distance from the shaft (11) axis) is controlled by the distance from the inwards facing surface (87) of the nut or locating feature to the inner end of the insert (80). The inwards facing surface (87) of the nut or locating feature is axially constrained by an abutment on the bearing housing (20). The sensor (70) has an externally facing thread (71) which can be threaded into an internally facing thread (21) in the insert.

(15) When the sensor is threaded into the insert, an inwards facing surface (76) on the sensor abuts an outwards facing surface on the insert, thus setting the depth of the sensor in the insert. The depth of the insert (in the bearing housing) is set in a similar method with the inwards facing surface (87) of the insert abutting an outwards facing surface of the bearing housing. Thus the resultant air gap between the end (73) of the sensor and the rotating inner race (102) is set.

(16) The end of the tubular part (84) of the insert locates in the window (100) of the outer race (101), thus keeping the outer race window (100) aligned with the axis of the sensor so that the sensor can be re-inserted into its correctly operating position. In a manner similar to the assembly of the sensor directly into the bearing housing, the outer race (101) of the REB is held in position (such that the window (100) in the outer race is aligned with the axis of the sensor) by a magnetic tool inserted into the REB bore (23) before the closure to the REB is assembled.

(17) In this design, the tubular end (84) of the insert (80) thus provides a means of keeping the window (100) in the outer race aligned with the axis of the speed sensor (enabling simple service replacement of the speed sensor) while also providing axial and angular constraint for the outer race (or cartridge) relative to the bearing housing (20).

(18) In a variation to the first and second embodiments of the invention, the insert (80) can be pressed or staked into the bearing housing or soldered or welded, as long as the axial air gap dimension between the end (73) of the sensor and the outside surface of the shaft (11) is maintained and the interface provides for an oil tight seal with the bearing housing to prevent oil leakage. Towards the outer end of the insert (80) is a generally cylindrical outside surface (83), which is pressed or shrunk into a generally cylindrical bore (92), concentric with the axis of the speed sensor (80) in the bearing housing to provide alignment with the desired axis of the sensor. The insert (80) is constrained in an outward direction by staking (91) of the bearing housing material over the outward facing surface of the flange (90).

(19) In further variations to the design, the insert (80) could be constrained in the bearing housing in an outward direction by other mechanical or chemical means such as welding or bonding, or by simply a greater shrink fit of the bore (92) with the surface (83) of the outside of the insert.