JPH05125951A - Exhaust gas turbine supercharger - Google Patents

Abstract

PURPOSE:To provide a turbocharger with durability and to reduce mechanical loss and the amount of lubricating oil by disposing a rolling bearing on the compressor side of a rotary shaft connecting a compressor to a turbine, and a sliding bearing on the turbine side of the shaft. CONSTITUTION:An exhaust gas turbine supercharger has a turbine shaft 5 serving as a rotary shaft connecting the impeller 2 of a compressor 1 to the wheel 4 of a turbine 3. A ball bearing serving as a rolling bearing is disposed on the compressor side of the turbine shaft 5. A floating metal (floating bush bearing) 7 serving as a sliding bearing is disposed on the turbine side of the turbine shaft 5. The supercharger is so formed that its axial diameter (a) at the position of the ball bearing 6 is smaller than its axial diameter (b) at the position of the floating metal 7. With such constitition, the advantages of the bearings are properly exhibited and durability is provided and mechanical loss and the amount of lubricating oil can both be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas turbine supercharger.

[0002]

2. Description of the Related Art An exhaust gas turbine supercharger (turbocharger) is well known as a device for supercharging exhaust gas energy emitted from an internal combustion engine. The structure consists of a turbine wheel (impeller) and a compressor impeller connected by a common rotating shaft. By applying exhaust gas to the wheel, the coaxial compressor is rotated to compress air, which is then transferred to the internal combustion engine. It is designed to be supplied to the combustion chamber of the engine. The rotating body is supported by a bearing housing having a predetermined shape via a bearing that is appropriately arranged on the rotating shaft.

[0003]

By the way, a rolling bearing or a sliding bearing (floating bush bearing, etc.) is used as the bearing. Rolling bearings are the most desirable as bearings for exhaust gas turbine superchargers, because they have low friction and therefore have a small mechanical loss and require a small amount of oil supply. However, rolling bearings generally have a short life,
In particular, since the temperature of the turbine becomes high due to exhaust gas, even if a high quality material is used, its durability is limited.
For this reason, in conventional trucks and the like, durable sliding bearings have been adopted, and there has been no choice but to compromise in terms of mechanical loss and refueling amount.

Therefore, in view of the above circumstances, the present invention was devised to provide an exhaust gas turbine supercharger which is durable and can reduce mechanical loss and oil supply.

[0005]

According to the present invention, a rolling bearing is arranged on the compressor side of a rotary shaft connecting a compressor and a turbine, and a sliding bearing is arranged on the turbine side.

Further, it is desirable that the rotary shaft is formed so that the shaft diameter at the position of the rolling bearing is smaller than the shaft diameter at the position of the sliding bearing.

[0007]

With the above construction, the rolling bearing supports the rotary shaft on the compressor side, which has a relatively low temperature, and the sliding bearing supports the turbine shaft, which has a high temperature.

Further, since the rotary shafts are formed with different shaft diameters, the load on the rolling bearing is reduced.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of an exhaust gas turbine supercharger according to the present invention. This exhaust gas turbine supercharger includes a turbine shaft 5 that is a rotating shaft that connects an impeller 2 of a compressor 1 and a wheel 4 of a turbine 3.
The ball bearing 6 serving as a rolling bearing is disposed on the compressor side, and the floating metal (floating bush bearing) 7 serving as a sliding bearing is disposed on the turbine side.

The turbine shaft 5 extends integrally with the shaft center of the turbine wheel 4, and the other end penetrates the shaft center of the impeller 2 of the compressor 1 and is fastened by a nut 8 at its tip. The diameter of the turbine shaft 5 closer to the compressor than the position of the ball bearing 6 is reduced, and the inner ring 10 of the ball bearing 6 is fitted to the step portion 9 thereof. That is, the shaft diameter a at the position of the ball bearing 6 is formed to be smaller than the shaft diameter b at the position of the floating metal 7. The inner ring 10 of this ball bearing 6
The turbine shaft 5 and the turbine shaft 5 are loosely fitted to each other so that the torque is held by the tightening force in the axial direction. The ball bearing 6 receives the thrust force generated in the rotating region under high load.

A common bush (sleeve) 12 is provided between the ball bearing 6 and the floating metal 7 and the bearing housing 11, and these bearings (6, 7) are held at predetermined positions. There is. Further, the bush 12 and the ball bearing 6 are fitted by shrink fitting or press fitting, and the bush 12 at this position
The inner diameter of is expanded and the outer ring 13 of the ball bearing 6 is attached to the inner surface of the inner surface of the outer ring so that the axial positioning can be easily performed.

In the bearing housing 11, an oil supply passage 14 is provided.
Is formed, and oil can be supplied to the floating metal 7 through the oil hole 15 formed in the bush 12. The ball bearing 6 is not provided with the oil supply passage 14, and oil is supplied (mist oil supply) by the oil atmosphere on the floating metal 7 side.

In addition, a ring 16 for removing oil is provided between the ball bearing 6 and the compressor 1.

With this structure, the floating metal 7 pivotally supports the turbine shaft 5 on the high temperature side of the turbine, and the ball bearing 6 pivotally supports on the compressor side of relatively low temperature, which is an advantage of each bearing. It is possible to obtain an exhaust gas turbine supercharger that is properly exhibited, has durability, and can reduce mechanical loss and oil supply amount.

By reducing the diameter of the turbine shaft 5 at the position of the ball bearing 6, it is possible to reduce the factors that determine the life of the bearing (reduce the D _N value) and ensure its durability. .

Further, since the ball bearing 6 is supplied with mist, the cost of the oil supply mechanism can be reduced. Further, since the ball bearing 6 is fitted with the bush 12 by shrink fitting or press fitting, and is fitted with the turbine shaft 5 by clearance fitting, the ball bearing 6 can be handled like a cassette and the assemblability of parts is improved. You can

In this embodiment, the sliding bearing is a rotatable floating metal, but it may be a semi-floating bush bearing whose rotation is restricted by a pin or the like. Further, a predetermined gap S may be formed between the bush 12 and the bearing housing 11 so that the function of the damper is added by the oil film. Further, as rolling bearings, ball bearings may be doubly arranged side by side in the axial direction. Alternatively, a gap may be provided between the bush 12 and the bearing housing 11, and axial positioning may be performed by providing a step on the bush 12.

[0019]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) According to the configuration of claim 1, desired durability can be obtained, and further, mechanical loss and oil supply amount can be reduced.

(2) According to the configuration of claim 2, the durability of the rolling bearing is further improved.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of an exhaust gas turbine supercharger according to the present invention.

[Explanation of symbols]

 1 Compressor 3 Turbine 5 Turbine shaft (rotary shaft) 6 Ball bearing (rolling bearing) 7 Floating metal (sliding bearing)

Claims (2)

[Claims] 1. An exhaust gas turbine supercharger characterized in that a rolling bearing is arranged on the compressor side of a rotary shaft connecting a compressor and a turbine, and a slide bearing is arranged on the turbine side. 2. The exhaust gas turbine supercharger according to claim 1, wherein the rotary shaft is formed such that a shaft diameter at a position of the rolling bearing is smaller than a shaft diameter at a position of the sliding bearing.