JPS63297734A - Turbocharger - Google Patents

Abstract

PURPOSE:To prevent the entry of an exhaust gas in a turbocharger having a turbine and a compressor connected each other by a shaft supported by a gas bearing, by providing means for generating a gas flow toward the turbine between the turbine and the gas bearing. CONSTITUTION:A turbocharger includes a turbine 1 and an impeller 2 of a compressor connected to the turbine 1 by a shaft 6. An impeller 21 as means for generating a gas flow toward a back surface of the turbine 1 is mounted on the shaft 6. Thrust receiving members 22 and 23 are mounted on the shaft 6 with a sleeve 24 interposed therebetween, and a porous member 25 as a gas bearing is engaged with an inner housing 26. The inner housing 26 is formed with a gas induction hole 27 for supplying a pressure gas to the porous member 25, and is also formed with a gas discharging hole 28 at a position apart from the gas induction hole 27. A center housing 5 is formed with a plurality of gas inlet holes 35 and gas outlet holes 36 communicated with a mounting space 41 of the impeller 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a turbo supercharger used in an internal combustion engine of an automobile or the like.

[Prior Art] Fig. 4 shows a conventional example in which a gas bearing is applied to the bearing of an automobile turbocharger, in which 1 is a turbine, 2 is a compressor impeller, 3 is a turbine housing, 4 is a compressor housing, and 5 is a compressor housing. It is a center housing. Reference numeral 6 denotes a shaft serving as a rotating shaft that connects the turbine 1 and the impeller 2. The shaft 6 is inserted into a bearing hole 8 of a journal bearing 7 fitted in the center housing 5 with a predetermined gap. Reference numeral 9 denotes a plurality of air supply holes provided in the center 7 housing 5, and a constricted portion 10 is provided at the tip so as to open into the bearing surface 11 of the shaft 6.

12 is an air supply groove provided on the outer periphery of the journal bearing 7;
It communicates with the air supply hole 9 and also with the air supply hole 13 provided in the center housing 5. 14.
Reference numeral 15 denotes an exhaust groove provided on the inner and outer circumferences of the journal bearing 7, avoiding the constricted portion 10 and the air supply groove 12;
．． 15 are communicated with each other through an exhaust hole 16. 17 is an exhaust port provided in the center housing 5, and the exhaust groove 15
has been contacted. Reference numeral 18 denotes a thrust bearing with an air supply hole 19 communicating with the air supply hole 13, and an impeller 2 at the tip of the air supply hole 19.
A diaphragm section 20 that opens on the back side of the diaphragm is provided.

In the above configuration, when pressurized gas is sent from an external compressor through the air supply hole 13, this pressurized gas is passed through the air supply groove 12 to the air supply hole 9, the constriction part 10, the air supply hole 19, and the constriction part. 2
0 and is ejected and supplied to the gap between the bearing surface 11 and the journal bearing 7 and the gap between the back surface of the impeller 2 and the thrust bearing 18, and the shaft 6 and the back surface of the impeller 2 float up, causing the journal bearing 7 and the thrust bearing 18 to flow. It is supported without sliding contact.

The pressurized gas supplied to the gap between the shaft 6 and the journal bearing 7 and the gap between the back surface of the impeller 2 and the thrust bearing 18 is
The exhaust port 17 passes through the exhaust groove 14, the exhaust hole 16, and the exhaust groove 15.
On the other hand, the turbine 1 side and impeller 2
It flows out to the side.

[Problems to be Solved by the Invention] However, in the above conventional example, since the turbine 1 is driven by engine exhaust gas, the turbine 1 and the turbine housing 3
Exhaust gas enters the journal bearing flap side through the gap between the
Carbon and other substances adhere to the shaft 6 and the journal bearing 7 and accumulate, deteriorating the function of the journal bearing 7, causing wear due to sliding contact between the shaft 6 and the journal bearing 7, and in severe cases causing seizure. There was a problem with it being damaged. In addition, the turbine 1 is heated to a considerably high temperature by exhaust gas, and the heat is directly applied to the shaft 6, causing the shaft 6 to thermally expand and the bearing clearance to change.
There was a problem that the bearing characteristics changed.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and is designed to prevent turbine-driving exhaust gas from entering the gap between the shaft and the bearing, and to reduce the thermal influence of the turbine on the shaft. The aim is to provide a turbocharger with improved performance.

[Means and effects for solving the problem] According to the present invention, in a turbocharger in which a shaft serving as a rotating shaft connecting a turbine and an impeller of a compressor is rotatably supported by a gas bearing, the turbine and the gas By providing means for generating a gas flow toward the turbine rear side between the bearing and the bearing, a gas flow from the gas bearing side toward the turbine rear side is generated.

[Embodiment] FIG. 1 shows a longitudinal sectional view of an embodiment of the present invention, and FIG. 2 shows a cross section taken along line AA in FIG. In FIG. 1, 1 is a turbine, 2 is a compressor impeller, 3 is a turbine housing, 4 is a compressor housing, and 5 is a center housing. 6 is a shaft as a rotating shaft connecting the turbine 1 and the impeller 2, and 21 is an impeller that is fitted on the shaft 6 and is a means for generating a gas flow toward the back side of the turbine. ), (b), vanes are provided on the outer peripheral surface or end surface so that when the shaft 6 rotates, a gas flow toward the back side of the turbine 1 is generated.

Reference numerals 22 and 23 designate thrust receiving members that are fitted onto the shaft 6 with a sleeve 24 that is fitted onto the shaft 6 interposed therebetween.

Reference numeral 25 is a porous material that is a gas bearing, and is fitted into the inner housing 26 by means such as shrink fitting or adhesion. 27 is an air supply hole for sending pressurized gas to the porous material 25 provided in the inner housing 26; 28 is an exhaust hole provided in a position avoiding the air supply hole 27 of the inner housing 26; Exhaust hole 2 provided
I am in contact with 9. The inner housing 26 has an elastic body 30 such as an O-ring attached to the inner circumference of the center housing 5.
It is fitted through. A cooling groove 31 is provided on the outer periphery of the inner housing 26, and a cooling space is formed by the elastic body 30. Cooling fluid is supplied to this cooling space from a supply port 32 provided in the center housing 5, and the inner housing 26 is cooled. The supplied cooling fluid is supplied to the supply port 3 of the center housing 5.
The liquid is discharged to the outside through a discharge port 33 provided at a position away from 2. The sleeve 24 fitted to the shaft 6 is inserted into the bearing hole 34 of the porous material 25 with a predetermined gap, and the thrust receiving members 22 and 23 are sandwiched between both end surfaces of the porous material 25 with a predetermined gap. . As shown in FIG. 2, the supply port 32 and the discharge port 3 of the center housing 5
H is an exhaust port provided in the center housing 5 similarly to the gas intake port 35. Filters (not shown) are installed in the openings 35 and 36 to prevent foreign matter from entering.
is provided. Reference numeral 37 denotes a partition wall member, which is fixed to the inner periphery of the center housing 5 with, for example, a C-shaped retaining ring 48, and is arranged around the outer periphery of the impeller 21 with a predetermined gap therebetween. The air intake port 35 of the center housing 5 is provided on the partition wall member 3f.
a groove 39 communicating with the space 38 between the partition member 37 and the inner housing 26, and a through hole 42 communicating from the space 41 between the partition member 37 and the shielding member 40 to the exhaust port 36 of the center housing 5. It is provided.

A flange member 43 is bolted to the center housing 5 (not shown) and bolted to the compressor housing 4 via a support member 44. The flange member 43 is provided with an air supply hole 45 and an exhaust port 46, which communicate with an air supply hole 27 and an exhaust hole 28 provided in the inner housing 26, respectively. The center housing 5 is bolted to the turbine housing 3 via a support member 47, and at this time, the shielding member 40 is also inserted and fixed at the same time.

In the above configuration, when pressurized gas is sent from an external compressor through the air supply hole 45, this pressurized gas passes through the air supply hole 27 provided in the inner housing 26 and passes through the porous material 2.
5, sleeve 24, thrust receiving member 22.23
The sleeve 24 and the thrust receiving members 22 and 23 float up and are rotatably supported without coming into sliding contact with the porous material 25. The pressurized gas supplied to the gap between the sleeve 24, the thrust receiving member 22, 23, and the porous material 25 passes through the exhaust hole 2g provided in the porous material 25 and the exhaust hole 28 provided in the inner housing 26. hand,
While being exhausted to the outside from the exhaust port 46 provided in the flange member 43, it also flows out to the space 38 and the impeller 2 side.

Now, when the turbine 1 is driven by engine exhaust gas, the impeller 21 also rotates at the same time, and the gas flowing out from the gap between the porous material 25 and the thrust receiving member 23 and the intake port 3
5, the gas flows toward the back side of the turbine as shown by the arrow in FIG. 1, that is, the space 3.
8 to the space 41. space 41
The gas flowing into the center housing 5 passes through a through hole provided in the partition member 37 and is exhausted to the outside from the exhaust port 36 of the center housing 5.

According to the embodiment of the present invention, the gas flow generated as the impeller 21 rotates causes exhaust gas to flow from the gap between the turbine 1, the turbine housing 3, and the blocking member 40 to the gas bearing section made of the porous material 25. Intrusion can be reliably prevented, and the heat transferred from the turbine 1 heated by the exhaust gas is cooled in a portion of the shaft 6 near the turbine 1.

In this example, the porous material used as a gas bearing was formed by cold isostatic pressing (CIP) and fired, so that the particle size of the material was almost uniform and the open pores were almost uniformly distributed. The use of porous graphite provides a uniform distribution of gas flow through the porous material. This will be explained by comparing it with the conventional porous Graphite. here,
FIG. 5(a) is a model representation of the gas permeation flow rate distribution on the bearing surface of porous graphite in a conventional gas bearing, and FIG. FIG. 3 is a model-like diagram showing the distribution of gas permeation flow rate on the bearing surface. In the figure, A' is a modeled cross-section of porous graphite used in conventional bearings, A is a modeled cross-section of porous graphite used in this example, and B and B' are Diagram showing the distribution of gas permeation flow rate of each porous graphite, C
is a diagram showing that gas is supplied at a constant pressure.

In the conventional porous graphite A', each particle size of '' in the material particles is not uniform and the open pores are also distributed non-uniformly, so the distribution B' of gas permeation flow rate is not uniform. The material particles of porous graphite A in this example have uniform particle diameters, and open pores are almost evenly distributed, so that the distribution of gas permeation flow rate is almost uniform. As such porous graphite, for example, porous graphite with the trade name Cerafite (manufactured by Toshiba Ceramics) can be used. Furthermore, since porous graphite has a self-lubricating effect, it is possible to prevent scratches and seizure even if the bearing surface and the mating member come into contact.

In addition, since conventional porous graphite has an uneven gas permeation flow rate distribution as described above, the flow rate is adjusted using a resin or the like to make the gas permeation flow rate distribution uniform. When used in a turbocharger, if the bearing part becomes very high temperature, the resin etc. will melt and fly away, and the adjustment effect cannot be expected.The porous graphite of the embodiment of the present invention cannot be adjusted as described above. Since this is not necessary, a uniform gas permeation flow rate distribution can be obtained even in a high-temperature environment, and a good gas bearing can be achieved.

In the embodiments of the present invention, explanations have been given on the case where a multi-hole diaphragm is used as the gas bearing, but even when other types of gas bearings such as a self-diagnosis diaphragm, an orifice diaphragm, a surface diaphragm, etc. You can expect good results.

In the embodiment of the present invention, an impeller 21 and a thrust receiving member 23 are used, but a single member may function as an impeller and a thrust receiving member. The blade that generates the flow is attached to the shaft 6.
You can also have it.

In the embodiment of the present invention, gas is sucked in through the gas intake port 35, but means for forcibly supplying gas may be provided.

In the present invention, the gas flow is generated by the rotation of the impeller, but in addition, gas or (
and) means may be provided to blow out and supply the gas flowing out from the gas bearing directly toward the back side of the turbine.

Further, instead of using the impeller 21, a groove may be provided in the shaft 6 to form a gas film by a wedge effect as the shaft 6 rotates in the gap between the shaft 6 and the partition member 37. However, in this case, The shaft 6 is arranged so that the gas flow caused by the wedge effect is directed toward the back side of the turbine.
The direction of the groove is determined.

[Effects of the Invention] As explained above, the present invention is a means for generating a gas flow toward the back side of the turbine in the portion between the turbine and the gas bearing of the shaft serving as the rotating shaft that connects the turbine and the impeller. Providing an impeller has the effect of preventing exhaust gas from entering the gas bearing side through the gap between the turbine and the turbine housing, and also directs the heat transmitted from the turbine heated by the exhaust gas to the part of the shaft near the turbine. It has a cooling effect.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of an embodiment of the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is an overview of the impeller in the embodiment of the invention, and Fig. 4 is a conventional example. FIG. 5 is a longitudinal cross-sectional view of the porous graphite bearing surface permeation flow distribution model diagram. 1: Turbine, 2: Invera, 3: Turbine housing, 6: Shaft, 21: Impeller, 22 Ni-thrust receiving member, 23 Ni-thrust receiving member, 24 Ni-sleeve, 25: Porous material, 35: Gas intake, 36: Exhaust Mouth, 37: Partition member. Patent Applicant Canon Co., Ltd. Agent Patent Attorney Tetsuya Ito Agent Patent Attorney Tatsuo Ito Figure 2C Figure 5

Claims (8)

[Claims] (1) In a turbocharger in which a shaft serving as a rotating shaft connecting a turbine and an impeller of a compressor is rotatably supported by a gas bearing, a means for generating a gas flow toward the turbine between the turbine and the gas bearing. A turbo supercharger characterized by being equipped with. (2) The turbo supercharger according to claim 1, wherein the means for generating the gas flow comprises an impeller provided in a portion of the shaft near the turbine. (3) The impeller has a thick-walled cylindrical shape provided coaxially with the shaft, and a plurality of blades for generating gas flow toward the turbine side are provided on the outer peripheral side of the thick-walled cylindrical body. A turbo supercharger according to claim 2. (4) The impeller has a thick-walled cylindrical shape disposed coaxially with the shaft, and a plurality of blades for generating gas flow toward the turbine side are provided on the end face of the thick-walled cylindrical body. A turbocharger according to claim 2. (5) The turbo supercharger according to claim 1, wherein the means for generating the gas flow comprises a plurality of blades formed directly on the shaft. (6) A center housing is provided between the turbine and the impeller, a cylindrical inner housing coaxial with the shaft is provided within the center housing, a gas bearing is fitted within the inner housing, and the shaft is disposed within the gas bearing. A turbo supercharger according to any one of claims 1 to 5, characterized in that the turbocharger is equipped with a. (7) A turbo supercharger according to claim 6, characterized in that a space is formed between the center housing and the inner housing for a cooling fluid to flow along the outer peripheral surface of the inner housing. . (8) A partition member is provided facing the turbine side end surface of the inner housing, and a gas intake port communicating with the space between the partition member and the inner housing is provided in the center housing, and the space is connected to the gas bearing. an exhaust passage communicating with a gap between the shafts, configured to guide gas in the space to the turbine side of the partition member by means of generating the gas flow, and for releasing the guided gas to the outside; The turbo supercharger according to claim 6 or 7, characterized in that the partition wall member and the center housing are provided continuously.