JPS5965518A - Turbosupercharger - Google Patents

Abstract

PURPOSE:To improve the gas bearing performance by providing with an air compressor driven by an engine or a motor and feeding the high-pressure air generated in said air compressor into the lower part of a dynamic pressure type journal gas bearing which supports the revolution shaft of a turbosupercharger. CONSTITUTION:Turbine blades 13 of a turbosupercharger 2 are revolved by the exhaust gas discharged into an exhaust manifold 11 by the operation of an engine 1, and a compressor vane wheel 23 installed coaxially 12 with said vane wheel 13 is revolved, and air is supercharged to the engine 1. An air compressor 3 is operated through a transmission mechanism including a belt 5 by the revolution of the engine 1. The high-pressure air formed in the air compressor 3 is supplied into the dynamic pressure type journal gas bearing 19 of the turbo supercharger 2 through a discharge pipe 8 equipped with cooling fins 9, and an air film is formed between the bearing 19 and the revolution shaft 12 by feeding the high pressure air from an air feeding hole 21. Thus, contact between the revolution shaft 12 and the bearing 19 is prevened, and the durability of the bearing 19 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a turbocharger, and particularly to a small-sized turbocharger with high speed rotation suitable for small-sized automobile engines.

[Prior art]

In order to make the turbo supercharger lighter and more compact, the maximum rotational speed of the turbo supercharger used in small engines with a engine displacement of 2 or less is a high rotation speed of 150,000 or more. ing. At such high-speed rotations, if conventional oil-lubricated bearings are used, the overall efficiency of the υ turbocharger will drop by one level due to the large proportion of bearing loss. At 1:00, the effect of bearing loss is large in the low engine speed range where the turbine/output is small, and the rotation speed of the turbo supercharger does not increase, making it impossible to obtain the required supercharging pressure, resulting in a lack of output torque in the low engine speed range. Cause.

Therefore, if a gas bearing that uses air as the working fluid is used instead of an oil bearing, the power loss of the gas bearing will be approximately 1/2 of that of an oil bearing.
/10, so it is possible to significantly improve the overall efficiency. Additionally, oil bearings have an oil seal structure, but oil leaks and carbonization of oil due to surface heat on the turbine side can cause problems such as accelerating bearing wear. It also solves the problem.

There are two types of gas bearings: the dynamic pressure type, in which the rotating shaft is supported by a gas film generated by the rotation of the shaft, and the type in which high-pressure gas is supplied from the outside.
Static pressure is used to support the rotating shaft by pressure. In the case of a turbocharger, a dynamic pressure type gas bearing that does not require a high pressure air source is suitable.

With hydrodynamic gas bearings, the rotating shaft of the turbocharger comes into solid contact with the bearing when the engine is started or stopped.

For this reason, the bearings are made of wear-resistant materials and have a structure that completely absorbs the impact of contact.

In addition, in order for a hydrodynamic gas bearing to operate, the circumferential speed of the rotating shaft must be above a certain value, and when the engine is in an idle link state, the rotational speed of the turbo supercharger must be at its minimum. The rotating shaft rotates while rubbing against the bearing. Since the engine is operated in an idling state for a relatively long period of time, under such conditions the bearings will fail prematurely and the durability of the bearings will be reduced.

On the other hand, in hydrodynamic bearings, the pressure at the bearing section may be lower than the pressure at the turbine side, so exhaust gas enters the bearing section from the turbine side, raising the bearing temperature and reducing the strength of the bearing. In addition, foreign matter may enter the bearing portion and contaminate the bearing surface, causing problems such as corrosion and wear. Furthermore, bearings generate heat, so even gas bearings require cooling.

As described above, it has been extremely difficult to apply conventional hydrodynamic gas bearings to automobile turbochargers.

[Object of the Invention 1] The object of the present invention is to prevent the rotational axial force from coming into contact with the ball bearing surface even when the rotational speed of the turbocharger is low, and to seal and cool the +li+il bearing part. 'The purpose is to provide a complete range of dynamic pressure type gas bearing turbo turbines.

[Summary of the invention]

In principle, it is not necessary to supply high-pressure borrowed air from the outside for the operation of dynamic pressure type gas bearings, but in order to achieve bearing action even in low-speed rotation conditions, a small amount of intermediate-pressure air is supplied as an auxiliary. do. In order to supply this high-pressure air, a viewing compressor driven by an engine or electric motor is provided. The pressure of this air compressor is set to a value higher than the maximum turbine inlet pressure.

In the case of current gasoline engines for passenger cars, air pressure &
Is the pressure on the seashore I Ky '/cn? (gauge pressure) is sufficient.

The bearing load when the rotating shaft is rotating at low speed is determined by the weight of the rotor, which consists of the impeller and the shaft.The weight of the metal rotor of a small turbocharger is 400g or less, and if a ceramic material is used, the weight can be halved. do. Bearing part + fi'
If fc 8 cr/l, the bearing load is 0.05Kgf
/crIi, the rotor can be supported even at a small volume of air pressure #II'i.

Since the pressure at the bearing section is higher than at least the pressure at the turbine side, the air supplied to the bearing section flows to the turbine 4111. Therefore, leakage of exhaust gas from the turbine side can be prevented. At this time, the air flow transports the heat generated in the bearing, which also has the effect of cooling the bearing.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3.

Fig. 1 is a system diagram including the engine and the turbo supercharging system of the present invention. 1 is the engine body, 2 is the turbo supercharger. The air filter 7 is connected to the tip of the suction #6 of the air compressor 3. The discharge pipe 8 of the air compressor 3 is connected to the turbocharger 2. , the discharge pipe 8 is provided with cooling fins 9. The conopressor outlet of the turbo supercharger 2 is connected to the intake pipe of the engine 1. The turbine outlet is connected to the exhaust manifold 11 of the engine 1. has been done.

FIG. 2 is a longitudinal cross-sectional view of the turbocharger 2 of this actual hW example. The rotating shaft 12 is arranged almost horizontally, and the rotating shaft 12
A turbine impeller 13 is provided at one end of the turbine impeller 13, and a turbine casing 14 is arranged to surround the turbine impeller 13. The turbine casing 14 is fixed to the center housing 15 by bolts 16.

The heat shroud 17 is sandwiched between the center 7, housing 15 and the turbine casing 14, and the turbine impeller 13
and the center housing 15, and constitutes a heat insulating chamber 18. Inside the center housing 15, one dynamic pressure type journal gas bearing 19 is provided on each of the turbine side and the compressor side. A discharge pipe 8 of the air compressor 3 is connected to the central portion of the center 71 housing 15, and a flow path 20 is provided that connects the discharge pipe 8 and the outer circumference of the journal gas bearing 49. .

An air supply hole 21 communicating with the shaft hole is provided in the lower part of the journal gas bearing 19. A discharge hole 22 is provided in the upper part of the turbine side journal gas bearing 19, and a heat insulating chamber 18 is provided.
It leads to

A compressor impeller 23 is fixed to a side of the rotating shaft 12 opposite to the turbine impeller 13 with a nut 24 .

Compressor impeller 23? : The compressor casing 25 is arranged so as to surround the compressor casing 25.
is fixed to the center housing 15 by bolts 26. On the back of the compressor impeller 23, there is a back plate 2 that separates the compressor impeller 23 and the bearing part.
7 is provided, and the back plate 27 is fixed to the center 71 housing 15 with bolts 28. Compressor impeller 23 of rotating shaft 12 and journal gas bearing 1
A thrust disk 29 is provided between the compressor 9 and the rotary shaft 12 , and the thrust disk 29 is fixed to the rotating shaft 12 via a compressor impeller 23 . Thrust gas bearings 30 are provided on both sides of the thrust disk 29, and are fixed to the center 71 housing 15 and the nozzle grate 27, respectively.

8g3 is a sectional view of the hydrodynamic journal gas bearing 19 of FIG. 2 taken along a plane perpendicular to the rotational axis direction. 31
(bearing) is a housing and is fitted into a hole in the center housing 15. Shaft hole 32 of bearing housing 31
The rotating shaft 12 passes through the bearing housing 31 , and a gap 33 is provided between the inner circumference of the bearing housing 31 and the rotating shaft 12 .

A plurality of pads 34 are provided in the gap 33, and the space between the inner surface of the knot 34 and the rotating shaft 12 is formed to have a wedge-shaped cross section. A plurality of screw holes 35 for supporting the pad 34 are provided in the glaze receiver 1 housing 31, and a spring-loaded pivot 36 for supporting the pad 34 is inserted into the screw hole 35, and its position is determined by a machine screw 37. It is determined. An air supply hole 21 is provided at the bottom of the bearing housing 31, and a discharge hole 22 is provided at the top.

When the engine 1 operates, exhaust gas flows into the turbine casing 14 of the turbocharger 2 through the exhaust manifold 11, and the turbine impeller 13 operates. This causes the shaft 12 to rotate, transmitting power to the compressor blades and the root wheel 23, and supercharging air to the engine 1 through the intake pipe 10. When the engine 1 starts, the crankshaft 4 and belt 5
The air compressor 3 operates with all valves closed, sucks air through the entire near filter, and the compressed air is supplied to the bearing section of the turbocharger 2 through the discharge valve 8. The air supplied at this time is cooled by the fins 9.

The air supplied by the discharge pipe 8 flows through the flow path 20 and is guided to the lower part of the outer circumference of the journal gas bearing, and is passed through the air supply hole 21 provided in the bearing housing 31 to the rotating shaft 12.
It is supplied to the gap 33 on the outer periphery of. When the rotating shaft 12 is in a rotating state, an air film is formed between the rotating shaft 12 and the pad 34, producing a lubricating effect. Air supply hole 2
The air supplied from 1 flows through the gap 33 and exits through the exhaust hole 22.
flows out through the For this reason, a pressure distribution occurs around the rotating shaft 12 in which the static pressure is high at the lower part and low at the upper part, causing air to float above the rotating shaft 12. Therefore, when the engine 1 is in an idle link state, the rotating shaft 12
Even in a state where no air film is formed due to low speed rotation, the rotating shaft 12 floats, so the rotating shaft 12 does not come into contact with the pad 34, and the pad 34 is not damaged.

The air discharged from the exhaust hole 22 transports the heat generated inside the bearing, so it has the effect of cooling the bearing. (The air discharged from the journal gas bearing 19 on the turbine side flows into the insulation chamber 18, but since the pressure of the air supplied by the air compressor 3 is set higher than the pressure on the turbine side, the inside of the insulation chamber 18 Air flows through the heat shroud 17 and the rotating shaft 12
It flows into the back of the turbine impeller 13 through the gap between the two. Therefore, the exhaust gas flowing through the turbine casing 14 and the turbine impeller 13 does not leak into the bearing, thereby preventing the bearing from becoming contaminated and heated.

FIG. 4 shows another embodiment of a turbocharger. Rotating shaft 12
are provided in a substantially vertical direction, the rotor, compressor, and shank impellers 23 are provided at the top, and the turbine impeller 13 is provided at the bottom. 19 is a dynamic pressure type journal gas bearing. A thrust disk 29 is fixed to the rotating shaft 12 between the journal gas bearing 19 and the compressor impeller 23, and dynamic pressure type thrust gas bearings 30 are provided on the upper and lower surfaces of the thrust disk 29. . A discharge pipe 8 of the air compressor 3 is connected to the center housing 15.
A flow path 40 connected to the thrust gas bearing 30 is provided on the lower side of the thrust disk 29 . The thrust gas bearing 30 is provided with an air supply hole 41 . In addition,
The components other than the turbocharger are the same as the configuration shown in FIG. 1.

In the case of this embodiment, when the rotary shaft 12 is rotating at a low speed, the load of the rotor acts on the lower dynamic pressure type thrust gas bearing 30. Therefore, by supplying high pressure air to the thrust gas bearing 30, Rotation can also levitate the rotor.

〔Effect of the invention〕

According to the present invention, even when the rotational speed of the turbocharger is low, the rotating shaft can operate without contacting the gas bearing, so the bearing is not damaged, and the bearing can be sealed and cooled. Therefore, there are many effects that can improve the durability of the bearing.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of the entire embodiment of the present invention, Fig. 2 is a vertical sectional view of a turbocharger according to an embodiment of the present invention, and Fig. 3 is a dynamic pressure type of the turbocharger shown in Fig. 2. FIG. 4 is a cross-sectional view of the journal gas bearing portion taken along a plane perpendicular to the rotation axis, and FIG. 4 is a longitudinal cross-sectional view of a turbocharger according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Engine, 2... Turbo supercharger, 3... Air compressor, 13... Turbine impeller, 19... Dynamic pressure type journal gas bearing, 21... Air supply hole, 22・
...Discharge hole, z3...Compressor impeller, 29...
・Thrust disk, 30...Dynamic pressure type thrust gas bearing. Y 1 Figure 2 Figure 'fJ 3 Figure

Claims (1)

[Claims] 1. A turbine driven by exhaust gas from the engine and a compressor for supercharging air to the engine are provided on a rotating shaft arranged approximately horizontally, and the rotating shaft is equipped with a hydrodynamic journal gas A horizontal shaft type turbocharger supported by a bearing has an air-free air compressor directly driven by an engine or an electric motor, and supplies high-pressure air from the air compressor to the lower part of the hydrodynamic journal gas bearing. A turbo pumping machine featuring a flow path with gold film girders that guide the flow. 2. The turbocharger according to claim 1, wherein the air pressure supplied by the air compressor is set higher than the pressure on the turbine side. 3. A turbine driven by exhaust gas from the engine and a compressor that completely supercharges air to the engine are installed on a rotating shaft arranged almost vertically, and the rotating shaft is mounted on a vertical shaft supported by a dynamic thrust gas bearing. Sukegata's turbo over t3
It is characterized by having an air compressor that is directly driven by an engine on the beach, and a flow path that leads high-pressure observation from the air compressor to the lower part of the dynamic pressure type thrust gas bearing. The turbo is a machine. 4. The turbocharger according to claim 3, characterized in that the air pressure supplied from the live air compressor is set higher than the pressure on the turbine side.