JPS6355327A - Turbocharger - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a turbocharger (supercharging v1),
More specifically, it relates to a compact design turbocharger with an improved bearing support and oiling system. A turbocharger harnesses the energy of the exhaust gases from an internal combustion engine to fill the combustion chamber of the engine. This is a well-known device for compressing combustion air flowing into a combustion chamber. A turbocharger has two impellers mounted on opposite ends of a common shaft, each impeller being allowed to rotate in its own free turn within the turbocharger housing. ing. One impeller functions as a fluid motor and is rotated by exhaust gas from the engine. The other impeller.

Usually called a pump or compressor impeller, it draws in outside air and compresses it to a higher pressure, increasing the flow of combustion air into the engine, for example.
thereby making it available to increase the power of the engine.

Typical turbocharger designs must rotatably support the impeller shaft with a bearing assembly located between the two impellers; such bearing assemblies typically support the shaft of the impeller. It is a housing with a journal type bearing around it. The structure of this type of bearing assembly is two.

For example, journal bearings tend to render turbochargers at least partially ineffective, especially at low speeds, and these bearings require significant internal and external clearances, which are extremely This is because a large compressor and turbine impeller clearance is required. Journal bearings also have relatively high friction losses. Additionally, it has an impeller lignically cantilevered from the end of the shaft. In particular,
- The reactive force caused by the journal bearing leader is further increased due to the tilting of the impeller, which requires a larger impeller clearance.

To minimize the reactive forces associated with the use of journal pairings, the diameter of the shaft should be as small as possible to reduce friction losses, and the span between the bearings should be as large as possible to minimize impeller tilt. This is what is normally done. As a result, the shaft tends to be quite flexible. With the impellers cantilevered apart at the ends of such flexible shafts, the high speed rotation of the impeller group may result in an unstable dynamic system that poses a risk of first bending or a high degree of risk. , or by some kind of braking means associated with the zero impeller group on which the bending is applied,
Only a barely stable dynamic system is achieved.

Journal bearings also require high hydraulic pressure to support the impeller group with a hydrodynamic oil film and a large amount of oil. The reason for the large amount of oil is to remove the heat generated in the journal bearing and the heat obtained from the turbine section due to viscous friction. Oil is typically supplied by an inconvenient route from the engine oil system. Since the engine sometimes develops sufficient oil pressure and needs to supply this to the turbocharger, when starting a conventional turbocharger, there are times when there is little or no oil, or the journal bearing temporarily acts as a bushing. The vehicle is driven with only 100% of oil remaining.

Proposals to reduce the above problems by replacing journal bearings in turbochargers with other types of bearings have met with limited success. The use of ball bearings in turbochargers, for example to support the impeller shaft, poses other problems; ball bearings do not have vibration isolation capabilities, and traditional designs suffer from bending over the operating range. Due to the danger, a fluid film damper of the type must be provided.
Furthermore, exposure to high temperatures tends to reduce the hardness of the bearing, thereby reducing its useful life. The bearings can experience very high temperatures after the hot turbocharger is closed.

This is commonly referred to as "soakback" and as the cooling effect provided by the air flow through the compressor section ceases, the residual heat in the turbine section increases the temperature of the entire turbocharger.

Accordingly, one object of the present invention is to provide a turbocharger having a bearing assembly in which a relatively short, thick-walled shaft is supported in a ball bearing, and the ball bearing supports the nose of a compressor impeller. .

Another object of the invention is to provide a turbocharger having a housing with ceramic parts and a metal heat sink to prevent bearing damage caused by 'soakback'.

Yet another object of the invention is to provide a turbocharger that is relatively easy to assemble and has a reduced number of parts.

Yet another object of the invention is to provide a turbocharger with an improved self-contained lubrication system.

Further objects, advantages, and features of the invention will become apparent from a detailed consideration of the arrangement and construction of the components set forth in the following detailed description in conjunction with the accompanying drawings.

In short, the present invention comprises turbine and compressor impellers mounted at the ends of shafts and a housing defining an annular surface around each impeller, the housing comprising: ,
a wall between the impellers and from which the shaft extends, the wall having a ceramic portion adjacent the turbine impeller and a compressor impeller and a metal portion adjacent the ceramic portion; The compressor is characterized by having a ball bearing in the metal part of the housing for supporting the shaft, and a ball bearing for supporting the compressor impeller in the housing.

The invention further includes turbine and compressor impellers mounted at the ends of the shaft, and a housing defining an annular surface around each impeller, the housing defining an annular surface between the impellers and along the shaft. has an extending wall, and has a bearing mounted to the wall and supporting a shaft, a bearing mounted to the housing and supporting a compressor impeller, and a lubrication system, the lubrication system having a lubrication system in the compressor impeller. a central hole in the shaft, a connecting central hole in the shaft, and a radial hole in the shaft extending to a bearing supporting the shaft.

"Example" Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a turbocharger according to the present invention, the turbocharger including a housing including a turbine housing section 12 and a compressor housing section 14, each of which has an annular surface (volute-8h).
The turbid housing part 12 forming the aped toroid has an exhaust gas inlet 12 and a gas outlet and encloses a turbine impeller with blades. The compressor housing portion 14 has an air inlet 22 and includes a compressor impeller 24 provided with blades. Between the turbine impeller 20 and the compressor impeller 24,
Turbocharger housing! 1 is located, which wall 25 has a ceramic part 2B adjacent to the turbine impeller 20 and an adjacent metal part 28 adjacent to the compressor impeller 24. A shaft 30 connected to the turbine impeller 20 extends through a hole in the ceramic part 2B and the metal part 28. The shaft 30 is the compressor impeller 2
4, two impellers 20 and 24 are coupled for rotation in unison. Preferably, the shaft 30 is bolted to the turbine impeller 20 or is cast integrally therewith, and the compressor impeller 24 is threaded onto the end of the shaft.

Although the composition of the ceramic portion 26 of the wall 25 can vary considerably, the currently preferred material is a synthetic mica silicon dioxide matrix composite. The preferred material for metal portion 28 is cast iron because its coefficient of thermal expansion matches that of the preferred ceramic material.

The impellers 20 and 24 are connected by a shaft 30.

It is rotatably supported by ball bearings 32 and 34. The bearing 32 is located within the metal portion 28 of the wall 25 and is connected to the turbine impeller 20 and the compressor impeller 24.
supports a shaft 30 extending between. A bearing 34 is mounted within a bearing housing 35 centrally located in the air inlet 22 by a plurality of struts and supports the nose or end of the compressor impeller 24. The strut a6 is preswirled.
+) The trailing edge of an articulated wing may be shaped and oriented to function as a device or the strut 3B may function as a movable introductory vane to improve airflow within the compressor portion of the turbocharger 10. can be provided. Rotatable spacers 37 and 38 are located on the compressor side of the bearing 32 and on the turbine side of the bearing, respectively, each spacer having a respective piston ring 39.

Bearings 32 and 34 are lubricated by oil contained in a sump 40 located within compressor housing portion 14 . Oil is pumped through a delivery line 42 and a hollow nipple 43 to a central hole 44 in compressor impeller 24 leading to a coaxial central hole 46 in shaft 30 . Although the delivery line 42 may extend into the sump 40, preferably the delivery line is stopped above the oil level and the wick 41 extends from the delivery line into the sump so that the air and oil mixture flows into the bearings 32 and 34.
By using different types of wicks, the flow of oil to the bearings is reduced and is generally less than that supplied by the delivery line alone. . As best shown in FIG. 2, the portion of the compressor impeller 24 adjacent the bearing 34 is provided with a plurality of radial holes 48 extending from the central bore outwardly into the bearing area. Similarly, shaft 30 includes a plurality of radial holes 50 extending from bore 4B into the bearing area, as shown in FIG. An oil return opening 52 extends from the bearing 34 to the oil sump 40 and an oil return hole 54 extends from the bearing 32 to the metal portion 25 of the wall 25.
It extends through to the oil sump. To simplify the structure,
The radial hole 48 in the compressor impeller 24 is
It can also be omitted, in which case the oil flow path to the bearing 34 is connected to the terminal of the compressor impeller and the nipple 4.
The gap between 3 and 1 makes them the same party.

On one side of the bearing 32 opposite the radial hole 50 is a spacer having a plurality of small radial blades as a centrifugal pump that together pull the oil through the bearing. Similarly, the bearing 34 opposite the radial hole 48 also has a spacer 3 having a plurality of radial blades 58 which together act as a centrifugal pump to pull oil through the bearing.
8 is provided.

A particularly preferred configuration of the metal part 28 of the housing wall 25 is:
This is illustrated in the plan view of FIG. A plurality of radially extending fins BO are provided on the surface of the metal portion 28 adjacent to the ceramic portion 26 . The number of fins and their shape can vary considerably. The general purpose of the fins is to provide good contact between the metal part 28 and the ceramic part 28, especially when casting a flowing ceramic-containing material over the metal part and then solidifying this material. . The fin 60 has a metal part 28 and a ceramic part 2.
Promote good bonding between 8 and 8. In the embodiment described above, the bottom fin 80 is formed much thicker than the other fins so that the oil return hole 54 can be easily formed in the metal part of the wall 25 by means such as a drill. can be done. FIG. 5 shows the currently preferred shape and height of the fins 60.

In operation of turbocharger 10, exhaust gas from internal combustion engine 4 (not shown) enters turbine inlet 16, passes through turbine impeller 20, causing the impeller to rotate, and then exits from outlet 16. leak. The rotation of the turbine impeller 20 is transmitted to the turbine impeller which draws air through the inlet 22, compresses the air, and then supplies the air to the engine.

Rotating compressor impeller 24 and shaft 30 act as a centrifugal pump and draw oil from sump 40 to delivery line 42 and through nipple 43 to shaft center hole in compressor impeller 24 and hole 4B in shaft 30. The centrifugal force due to the rotation of the feeding impeller 24 and shaft 30 draws oil outwardly through radial holes 48 and 50 and then through circulation bearings 32 and 34 by blades 58 and 58 of spacers 37 and 38, respectively. The oil is at the compressor inlet 22
The air is cooled as it passes through an exit pipe in the flow path.

When the turbocharger stops operating, bearing 3
Damage to 2 and 3 is effectively prevented by the heat resistance of the ceramic part 2B and the heat shield by the metal part 28 of the wall 25, which acts as a cooling radiator. As a result, “turbocharger 10 due to soakback 9, especially bearing 3
Damages 2 and 34 are resolved.

As is clear from the above description, the turbocharger 10 according to the invention is such that the shaft 30 is so short and has a relatively long diameter that there is no risk of the shaft first bending outside the operating range of the turbocharger. It is sufficiently rigid that there is little or no need for vibration isolation, and by having the compressor impeller nose supported by ball bearings 34, one cantilever impeller is eliminated and a compact A long span between the bearings is achieved by the recess, and the compressor impeller acts as a very sturdy shaft. As a result, the slope of the impeller is drastically reduced, so that the clearances of the compressor and turbine impellers 20 and 24 with respect to the housing 11 can be made very small;
This improves the efficiency of the turbocharger. The use of ball bearings 32 and 34 considerably reduces bearing friction compared to journal type bearings, which further contributes to the efficiency of the turbocharger.
The walls 25 between the four tend to reduce heat loss from the turbine section, which also increases the efficiency of the turbine.

Similarly, walls 25 having ceramic portions 28 with metal portions 28 acting as cooling radiators tend to reduce heat gain in the compressor portion of the turbocharger, which improves compressor efficiency. . wall 2
The ceramic portion 26 of 5 reduces thermal loads on the bearing to increase bearing life, reduces the amount of oil flow required to cool the bearing, and allows the bearing to be assembled with lower temperature resistant materials. shall be.

Furthermore, by having a self-contained lubrication system, traditional line oiling to the engine lubrication system is eliminated. Also,
A self-contained lubrication system allows the use of lubricants specifically suited to the demands of the turbocharger environment in place of conventional engine oil.

Although what is considered to be a desirable embodiment of the present invention has been described above with reference to the drawings, those skilled in the technical field will appreciate the following:
It will be apparent that various changes and modifications may be made without departing from the invention as defined in the appended claims.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a turbocharger according to the present invention, FIG. 2 is a partially detailed view of the lubrication system of the turbocharger shown in FIG. 1, and FIG. 3 is a diagram of the lubrication system of the turbocharger shown in FIG. Detailed views of other parts: - Figure 4 is a plan view of a preferred embodiment of a metal heat sink of the housing wall located between the turbine section and the compressor section of the turbocharger shown in Figure 1;

Claims (19)

[Claims] (1) having turbine and compressor impellers mounted at the ends of shafts and a housing defining an annular surface around each impeller, the housing being between the impellers and extending from the shaft; a wall having a ceramic portion adjacent the turbine impeller and a metal portion adjacent the compressor impeller and the ceramic portion; and a ball supporting a shaft in the metal portion of the wall. A turbocharger comprising a bearing and a ball bearing supporting a compressor impeller in the housing. (2) A turbocharger according to claim 1, wherein the housing includes a bearing housing mounted at the inlet adjacent to the compressor impeller, and the bearing housing includes a bearing supporting the compressor impeller. (3) A turbocharger according to claim 2, wherein the bearing housing is attached to the inlet by a plurality of struts. (4) In the turbocharger according to claim 1, a central hole in the compressor impeller, a connecting central hole in the shaft, and a radial hole in the compressor impeller extending to a bearing supporting the compressor impeller; The turbocharger further includes a lubrication system having a radial hole in the shaft extending into a bearing supporting the shaft. (5) A turbocharger according to claim 4, wherein the lubrication system further comprises an oil sump contained in the housing and a wick extending from the oil sump to a delivery line leading to one of the central holes. Charger. (6) A turbocharger according to claim 5, wherein the delivery line extends into a central hole in the compressor impeller. (7) A turbocharger according to claim 5, wherein the lubrication system includes an oil return opening extending from a bearing supporting the compressor to the oil sump, and an oil return hole extending from the bearing supporting the shaft to the oil sump. Charger. (8) A turbocharger according to claim 1, in which a ball bearing in the housing supports the nose of the compressor impeller. (9) A turbocharger according to claim 2, wherein a ball bearing in the bearing housing supports the nose of the compressor impeller. (10) having a turbine impeller and a compressor impeller mounted at the end of a shaft, and a housing defining an annular surface around each impeller, the housing being between the impellers and extending from the shaft; a bearing attached to the wall and supporting a shaft; a bearing attached to the housing and supporting a compressor impeller; and a lubrication system, the lubrication system having a central axis in the compressor impeller. a hole, a connecting center hole in the shaft,
A turbocharger having a radial hole in the shaft that extends into a bearing that supports the shaft. (11) A turbocharger according to claim 10, wherein the housing includes a bearing housing attached to an inlet adjacent to a compressor impeller, and the bearing housing includes a bearing supporting the compressor impeller. . (12) A turbocharger according to claim 10, wherein a bearing attached to the housing supports the nose of the compressor impeller, the housing includes a hollow nipple adjacent the nose of the compressor, and a gap between the nipple and the nose. TURBOCHARGER LIMITED. (13) A turbocharger according to claim 12, further comprising a sump contained in the housing and a delivery line leading from the sump to a nipple continuous with a central hole in the compressor impeller. There is a wick and a turbocharger. (14) The turbocharger according to claim 13, wherein the lubrication system further includes an oil return opening extending from the bearing supporting the compressor to the oil sump, and an oil return hole extending from the bearing supporting the shaft to the oil sump. turbocharger. (15) A turbocharger according to claim 10, wherein the lubrication system includes a radial hole in the compressor impeller extending adjacent to a bearing supporting the compressor impeller. (16) A turbocharger according to claim 10, wherein the lubrication system includes a rotatable spacer adjacent to a bearing supporting a compressor impeller, the spacer having a plurality of blades. (17) A turbocharger according to claim 10, wherein the lubrication system includes a rotatable spacer adjacent to a bearing supporting the shaft, the spacer having a plurality of blades. (18) A turbocharger according to claim 17, wherein the lubrication system includes a rotatable spacer adjacent to a bearing supporting a compressor impeller, the spacer having a plurality of blades. (19) In a turbocharger according to claim 17, the radial hole extends to one side of the bearing and the spacer is located on the other side of the bearing such that the blades of the spacer pull lubricant through the bearing. turbocharger.