JP2005147029A - Turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems of a turbocharger of shortening of endurance life of a radial bearing and a thrust bearing or atmospheric pollution caused polluted by the generation of smoke by changing lubricant for the radial bearing and the thrust bearing from circulation type oil to air. <P>SOLUTION: In the turbocharger wherein a turbine shaft 1 for transmitting rotation of turbine blades 2 to compressor vanes 3 is supported by the radial dynamic pressure bearings 4 and 5 and the thrust dynamic pressure bearings 6 and 7, the radial dynamic pressure bearings 4 and 5 and the thrust dynamic pressure bearings 6 and 7 are respectively formed of a radial dynamic pressure bearing and a thrust dynamic pressure bearing respectively using air as an operating fluid. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a turbocharger, and more particularly, to a turbocharger in which a turbine shaft that transmits rotation of a turbine blade to a compressor blade is supported by a radial bearing and a thrust bearing.

  In turbochargers that perform supercharging using exhaust gas generated in an internal combustion engine, circulating oil is used to lubricate radial bearings and thrust bearings that support the turbine shaft. Conventionally, there has been known a hybrid charger in which a turbine shaft for transmitting rotation of a turbine blade to a compressor blade is supported by a radial bearing and a thrust bearing (see Patent Document 1).

JP 11-311243 A

  However, in a turbocharger that uses circulating oil to lubricate the radial and thrust bearings that support the turbine shaft, the high temperature of the exhaust gas is transmitted to the radial and thrust bearings through the turbine blades and turbine shaft. As a result, it is difficult to achieve sufficient lubrication performance due to the high temperature of the oil, and there is a problem that the service life of the radial bearing and the thrust bearing may be shortened. In addition, since foreign matters such as sludge may be mixed in the circulating oil, there is a problem that the bearings may be damaged by the foreign matters and their service life may be shortened. Furthermore, there is a problem that oil as a lubricant leaks to the turbine side as white smoke exhaust, and the exhaust may pollute the atmosphere. These problems are obstacles to increasing the rotational speed of the turbine shaft.

  The present invention has been made in view of the above problems, and by making it possible to change the lubricant of a radial bearing or thrust bearing from circulating oil to air, the service life of the radial bearing or thrust bearing is improved. An object of the present invention is to provide a turbocharger that can solve the problem that the battery life may be shortened and the problem of air pollution caused by the generation of white smoke.

  Another object of the present invention is to provide a turbocharger capable of suppressing leakage of air used as a lubricant by a thrust bearing.

  A turbocharger according to the present invention is a turbocharger in which a turbine shaft for transmitting rotation of a turbine blade to a compressor blade is supported by a radial bearing and a thrust bearing, and the radial bearing has a radial dynamic pressure bearing using air as a working fluid. (Claim 1).

  By using the above means, it is not necessary to use circulating oil for lubrication of the radial bearing, and the radial bearing is lubricated by air, so that sufficient lubrication performance is exhibited even at high temperatures, and foreign matters such as sludge are mixed. As a result, the service life of the radial bearing is improved. In addition, no white smoke is generated.

In the present invention, it is also possible to adopt a configuration in which the thrust bearing is a thrust dynamic pressure bearing using air as a working fluid (claim 2).
When this configuration is adopted, it is not necessary to use circulating oil for lubrication of the thrust bearing, and the thrust bearing is lubricated by air, so that sufficient lubrication performance is exhibited even at high temperatures. Moreover, since the foreign matter such as sludge is not mixed, the service life of the thrust bearing is improved. In addition, no white smoke is generated.

  Furthermore, in the present invention, it is desirable that the thrust dynamic pressure bearing has a sealing function. According to this configuration, the situation where air as the working fluid leaks to the outside due to the sealing function of the thrust dynamic pressure bearing is suppressed or prevented.

  As described above, according to the present invention, since the radial bearing or the thrust bearing is changed to the radial dynamic pressure bearing or the thrust dynamic pressure bearing using air as a working fluid, there is no need to use a circulating oil as a lubricant. The problem that the service life of radial bearings and thrust bearings may be shortened has been improved, and even if air as a working fluid leaks, the air is a component of white smoke that causes air pollution. Since the oil gas is not included, the situation where the air is polluted by the leaked working fluid does not occur. Further, in the case where the thrust dynamic pressure bearing has a sealing function, leakage of air used as a lubricant is suppressed by the thrust bearing, so that a situation in which the leaked air contaminates the atmosphere is less likely to occur.

  FIG. 1 is a sectional view schematically showing a turbocharger according to an embodiment of the present invention, FIG. 2 is an explanatory view showing a schematic structure of a radial dynamic pressure bearing, and FIG. 3 is an explanation showing a schematic structure of a thrust dynamic pressure bearing. FIG.

  As shown in FIG. 1, in the turbocharger of this embodiment, the rotation of the turbine blade 2 accommodated in the turbine chamber 2A is transmitted by the turbine shaft 1 to the compressor blade 3 accommodated in the compressor chamber 3A. ing. The turbine shaft 1 is supported at two locations by radial dynamic pressure bearings 4 and 5, and a back surface 21 formed by a disk surface of the turbine blade 2 and a back surface 31 formed by a disk surface of the compressor blade 3 are thrust. These are supported by dynamic pressure bearings 6 and 7, respectively. The radial dynamic pressure bearings 4 and 5 and the thrust dynamic pressure bearings 6 and 7 are arranged in an internal space 91 of the bearing housing 9 provided with the water jacket 8.

  In this turbocharger, when the high-temperature (for example, about 800 ° C.) exhaust gas G1 discharged from the internal combustion engine flows into the turbine chamber 2A and rotates the turbine blade 2, the rotation of the turbine blade 2 is compressed by the turbine shaft 1. It is transmitted to the blade 3. Then, the air A1 sucked into the compressor chamber 3A is compressed by the rotation of the compressor blade 3 and is supercharged, for example, into the combustion chamber of the engine. Further, the turbine shaft 1 is positioned in the radial direction and the axial direction by the radial positioning action exerted by the two radial dynamic pressure bearings 4 and 5 and the axial positioning action exerted by the thrust dynamic pressure bearings 6 and 7. Rotate with.

  An intake path 92 for introducing outside air into the internal space 91 by natural intake air is communicated with the internal space 91 of the bearing housing 9, and a filter 93 is provided in the intake path 92. The radial dynamic pressure bearings 4 and 5 are radial dynamic pressure bearings using air introduced from the intake passage 92 into the internal space 91 as a working fluid, whereas the thrust dynamic pressure bearings 6 and 7 are intake air. This is a thrust dynamic pressure bearing using air introduced from the passage 92 into the internal space 91 as a working fluid.

  The radial dynamic pressure bearings 4, 5 are arranged between the radial dynamic pressure grooves 42, 52 formed on the inner peripheral surfaces of the sleeves 41, 51 arranged around the turbine shaft 1 with gaps S 1, S 2, respectively, and the turbine shaft 1. The bearing is formed between the outer surface and the housing 9 and is fixed to the housing 9 with a snap ring 10 and a buffer body 103 (described later). The radial dynamic pressure grooves 42 and 52 are formed, for example, in a V shape or a herringbone shape. The radial dynamic pressure grooves 42 and 52 may be formed on the outer peripheral surface of the turbine shaft 1. In the radial dynamic pressure bearing, when the turbine shaft 1 rotates, the air as the working fluid generates dynamic pressure in the gaps S1 and S2 by the action of the radial dynamic pressure grooves 42 and 52, and the turbine shaft 1 and the sleeves 41 and 51 are generated. The turbine shaft 1 rotates without contact with the sleeves 41 and 51.

  The thrust dynamic pressure bearings 6 and 7 are provided with bearing bodies 61 and 71 made of annular members arranged at the back of the rear face 21 of the turbine blade 2 and the rear face 31 of the compressor blade 3 with gaps S3 and S4 therebetween. In addition, pump-out grooves 62 and 72 are formed on the surfaces of the bearing bodies 61 and 71 facing the respective rear surfaces 21 and 31. The pump-out grooves 62 and 72 may be formed on the respective rear surfaces 21 and 31. In the thrust dynamic pressure bearings 6, 7, when the turbine blade 2 and the compressor blade 3 rotate together with the turbine shaft 1, the air as the working fluid generates dynamic pressure by the action of the pump-out grooves 62, 72, and the gap S 3, 3. The air film is held in S4, and therefore the turbine shaft 1 rotates without contact with the sleeves 41 and 51. Further, since the air pressure in the gaps S3 and S4 becomes higher than the surrounding pressure, the internal space 91 of the bearing housing 9 is prevented from leaking into the turbine chamber 2A and the compressor chamber 3A through the gaps S3 and S4. This is the sealing function of the thrust dynamic pressure bearings 6 and 7, and this sealing function can be regarded as a kind of mechanical sealing function.

  In the turbocharger of this embodiment, the radial dynamic pressure bearings 4, 5 and the thrust dynamic pressure bearings 6, 7 use air naturally aspirated into the internal space 91 of the bearing housing 9 through the intake passage 92 as the working fluid. Even if the temperature of the working fluid rises due to the influence of the high-temperature exhaust gas G1, the lubrication performance is not lowered thereby. Therefore, it is difficult to cause a situation in which the durability of the radial dynamic pressure bearings 4 and 5 and the thrust dynamic pressure bearings 6 and 7 is impaired due to the reduction of the lubricating performance of the working fluid. In addition, since the air naturally sucked into the internal space 91 of the bearing housing 9 is clean air from which dust is removed by the filter 93, the radial dynamic pressure bearings 4 and 5 and the thrust are caused by dust contained in the working fluid. It is also difficult for the dynamic pressure bearings 6 and 7 to lose their durability. In addition, the radial dynamic pressure bearings 4 and 5 and the thrust dynamic pressure bearings 6 and 7 are such that the sleeves 41 and 51 and the bearing main bodies 61 and 71 are the turbine shaft 1 as a rotating part, the rear surface 21 of the turbine blade 2, the compressor blade. 3 and non-contact rotation using air as the working fluid and excellent high-speed rotation characteristics. Therefore, it is possible to cope with an increase in the rotational speed of the turbine shaft 1. Furthermore, since the working fluids of the radial dynamic pressure bearings 4 and 5 and the thrust dynamic pressure bearings 6 and 7 are air that does not contain oil gas that generates white smoke, the working fluid leaks out of the bearing housing 9. However, there is an advantage that there is no room for the situation that the atmosphere is polluted by the leaked working fluid.

  Further, since the thrust dynamic pressure bearings 6 and 7 exhibit a sealing action similar to that of a mechanical seal as described above, it is difficult for air as a working fluid to leak and impair safety.

  In addition, when air is used as the working fluid for the radial dynamic pressure bearings 4 and 5 and the thrust dynamic pressure bearings 6 and 7, the bearing housing 9 is provided with a water jacket 8 and the cooling water is circulated through the water jacket 8 only. There is also an advantage that the dynamic pressure bearings 4 and 5 and the thrust dynamic pressure bearings 6 and 7 can be cooled.

  By the way, a turbocharger mounted in an automobile engine room is required to take measures to prevent external vibration from being directly transmitted to the radial dynamic pressure bearings 4 and 5 and the thrust dynamic pressure bearings 6 and 7. Therefore, in the turbocharger of this embodiment, as shown in FIG. 1, the radial dynamic pressure bearing 4 and the thrust dynamic pressure bearing 6 on the turbine side, which are easily affected by the temperature of the high temperature exhaust gas G1, have high temperature resistance characteristics. The radial dynamic pressure bearing 5 and the thrust dynamic pressure bearing 7 on the compressor side, which are not easily influenced by the temperature of the high-temperature exhaust gas G1, are attached to the bearing housing 9 via excellent metal leaf springs 101 and 102. The bearing housing 9 is attached via shock absorbers 103 and 104 having rubber elasticity such as O-rings. In this way, vibrations from the outside are absorbed by the metal leaf springs 101, 102 and the buffer bodies 103, 104, so that the vibrations are directly transmitted to the radial dynamic pressure bearings 4, 5 and the thrust dynamic pressure bearings 6, 7. Is suppressed.

1 is a cross-sectional view schematically showing a turbocharger according to an embodiment of the present invention. It is explanatory drawing which showed schematic structure of the radial dynamic pressure bearing. It is explanatory drawing which showed schematic structure of the thrust dynamic pressure bearing.

Explanation of symbols

1 Turbine shaft 2 Turbine blade 3 Compressor blade 4,5 Radial dynamic pressure bearing
6,7 Thrust dynamic pressure bearing

Claims (3)

In a turbocharger in which a turbine shaft that transmits rotation of a turbine blade to a compressor blade is supported by a radial bearing and a thrust bearing,
A turbocharger wherein the radial bearing is a radial dynamic pressure bearing using air as a working fluid. The turbocharger according to claim 1, wherein the thrust bearing is a thrust dynamic pressure bearing using air as a working fluid. The turbocharger according to claim 2, wherein the thrust dynamic pressure bearing has a sealing function.

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