JPH076538B2 - Air bearing type turbocharger - Google Patents

Description

The present invention relates to an air bearing turbocharger.

[Conventional technology]

In the air bearing type turbocharger, a top foil is used for forming a thrust bearing surface in a thrust bearing, and this top foil is elastically supported toward a thrust member by a bump foil. An example of such a structure is shown in FIG. 6, in which the top foil 1 and the bump foil 2 are arranged between the thrust member 3 and the thrust bearing member 4. As shown in FIG. 7, the top foil 1 has a rear end 5 viewed in the rotational direction of the thrust member 3 welded to the thrust bearing member 4 and a tip 6 freely movable. JP 60-8524
The publication also discloses a similar air bearing, in which the mounting surface of the top foil is mounted obliquely to the thrust member.

[Problems to be solved by the invention]

In the thrust bearing as described above, a high pressure gas film is formed between the top foil 1 and the thrust member 3 by the high speed rotation of the thrust member 3 to support the thrust force, but the rotation is low. At times, the pressure of the gas film does not become sufficiently large, so that the top foil 1 is thrust by the elastic force of the bump foil 2 and the thrust member 3
The thrust member 3 is pushed toward and easily comes into contact with the thrust member 3.
When the top foil 1 rotates while contacting the thrust member 3, there is a problem that seizure occurs.

[Means for solving problems]

The air bearing turbocharger according to the present invention defines a thrust member mounted on a rotary shaft, a pair of thrust bearing members mounted so as to sandwich the thrust member from both sides, and a space between the thrust bearing members. A ring-shaped thrust spacer inserted between the thrust bearing members on the outer peripheral side of the thrust member, and a top foil arranged between the thrust member and the thrust bearing member to form a thrust bearing surface. A bump foil for giving an elastic supporting force to the top foil, a part of which protrudes in the inner diameter direction so that the thrust spacer engages with an outer peripheral end of the top foil to receive the top foil. It is characterized by being formed.

〔Example〕

FIG. 2 is a view showing a part of a compressor and a part of a center housing of an air bearing type turbocharger. The air bearing type turbocharger has a rotary shaft 12 connecting a turbine wheel (not shown) and the compressor impeller 10, the rotary shaft 12 is rotatably supported by a center housing 16 by a radial air bearing 14, and a thrust air bearing 18. Supported for thrust direction movement. A disk-shaped thrust runner 20 is attached to the rotary shaft 12 to engage with the thrust air bearing 18, and the thrust runner 20 is fixed to the rotary shaft 12 by a nut 22 together with the compressor impeller 10.

As shown in FIG. 1, a pair of thrust air bearings 18 are provided so as to face each other so as to sandwich the thrust runner 20, and a ring-shaped thrust spacer 24 is provided between the pair of thrust air bearings 18 on the outer peripheral side of the thrust runner 20. Is located in. Thrust spacers 24 define the spacing between air bearings 18, thereby setting the bearing air film thickness to a predetermined value. These thrust air bearing 18 and thrust spacer 24 are the second
Installed in the diffuser case 26 as shown in the figure,
The position in the thrust direction is determined by fastening the center housing 16 and the diffuser case 26 with the bolt 28. The diffuser case 26 is connected to the compressor housing 30 and stopped by a snap ring.

Referring to FIG. 1 and FIG. 3, a top foil 32 for forming a thrust bearing surface is disposed in a space between the thrust runner 20 and the thrust air bearing 18, and the top foil 32 is elastically supported by the top foil 32. A bump foil 34 is located between the top foil 32 and the thrust air bearing 18 to provide force. The top foil 32 is formed of a thin fan-shaped plate as shown in FIG. 3, and a plurality of top foils 32 are arranged in the circumferential direction. Each top foil 32 is spot-welded 36 at its rear end when viewed in the direction of rotation of the thrust runner 20 shown by the arrow. The front end 38 of each top foil 32 can move about the rear end as a fulcrum, and the thin plate-shaped bump foil 34 urges the top foil 32 toward the thrust runner 20 and the rotation speed of the thrust runner 20 increases. A pressure is generated in the air bearing film formed between the top foil 32 and the thrust runner 20, and the bump foil 34 elastically supports the top foil 32 against this pressure.

The thrust spacer 24 is formed in a ring shape as described above, and as is clear from FIG. 1, the thickness of the outer peripheral side portion 24a has a size required as a spacer, and the inner peripheral side portion 24b is the outer peripheral side portion 24a. Smaller than the thickness of the outer peripheral side portion 24a and projecting in the inner diameter direction from the inner peripheral side portion 24b and the thrust air bearing 1
An annular groove 40 is formed between the groove 8 and the groove 8. Each top foil 3
2 is arranged so that the outer peripheral end of the fan shape enters the groove 40, and when the top foil 32 is biased toward the thrust runner 20 by the spring force of the bump foil 34, the inner peripheral side portion of the thrust spacer 24. 24b receives the top foil 32, which causes the top foil 32 to become a thrust runner.
It is possible to improve the durability of the thrust air bearing by suppressing the contact with the 20 and suppressing the occurrence of wear and the like.

4 and 5 show a second embodiment of the present invention, in which the inner peripheral side portion 24b is formed so as to project in the inner diameter direction along the entire circumference of the thrust spacer 24 in the first embodiment. Thus, in the second embodiment, an inner radial projection 24c is partially formed to overlap the rear end of each top foil 32, and extends considerably inward in the radial direction, as can be seen in FIG. ing. This corresponds to the fact that the welded portion 36 at the front end portion is provided along the entire front edge in the radial direction, so that the engagement portion at the rear end portion side is also lengthened so that not only the outer peripheral side of the top foil 32 but also the inner peripheral side thereof. It also means to prevent the rise of. The rear end portion 32a of the top foil 32 is bent stepwise as shown in FIG. 5, and the protrusion 24c in the inner diameter direction of the thrust spacer 24 has a thickness within the range of the folding step of the top foil 32. Therefore, the protruding portion 24c in the inner diameter direction does not come into contact with the thrust runner 20.

〔The invention's effect〕

As described above, according to the present invention, by controlling the lift of the top foil, the rotation at a light load is stabilized, and the thrust clearance can be managed in units of microns. In the charger, the man-hours for designing and manufacturing can be significantly reduced.

[Brief description of drawings]

1 is a partially enlarged view of the air bearing type turbocharger of FIG. 2, FIG. 2 is a sectional view showing a part of a compressor and a center housing of the air bearing type turbocharger, and FIG. 3 is a line III of FIG. -III, a sectional view similar to Fig. 3 of the second embodiment, Fig. 5 is a sectional view taken along line V-V of Fig. 4, FIG. 7 and FIG. 7 are diagrams for explaining the conventional technique. 12 …… Rotary shaft, 18 …… Thrust bearing member, 20 …… Thrust runner, 24 …… Thrust spacer, 32 …… Top foil, 34 …… Bump foil, 24b, 24c …… Projection part.

Claims (1)

[Claims] 1. A thrust member attached to a rotary shaft,
A pair of thrust bearing members mounted so as to sandwich the thrust member from both sides, and a ring shape inserted between the thrust bearing members on the outer peripheral side of the thrust member to determine a distance between the thrust bearing members. A thrust spacer, a top foil arranged between the thrust member and the thrust bearing member to form a thrust bearing surface, and a bump foil for giving an elastic supporting force to the top foil, An air bearing turbocharger, characterized in that a thrust spacer is formed so as to engage with an outer peripheral side end portion of the top foil and receive the top foil so that a part thereof projects in an inner diameter direction.