JP2005163644A - Turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve both rising characteristics at starting and high speed rotational characteristics, by supporting a turbine shaft by a bearing formed by the combination of a rolling bearing element with a dynamic pressure bearing element, in a turbocharger. <P>SOLUTION: In this turbocharger in which the turbine shaft 1 transmitting rotation of a turbine blade 2 to a compressor blade 3 is supported by bearings 4, 5, the bearings 4, 5 are formed by the dynamic pressure bearing elements 41, 51 supporting the turbine shaft 1, and the rolling bearing elements 45, 55 supporting the dynamic pressure bearing elements 41, 51 on the peripheral sides of the dynamic pressure bearing elements 41, 51. The dynamic pressure bearing elements 41, 51 can be commonly used by the same member as the inner rings 46, 56 of the rolling bearing elements 45, 55. <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 bearing.

  Conventionally, a turbine shaft of a turbocharger is supported by bearings provided at two locations on the turbine side and the compressor side, and a sliding bearing or a rolling bearing using a floating metal has been used for these bearings.

  FIG. 5 is a cross-sectional view schematically showing a conventional turbocharger. In this turbocharger, a turbine-side bearing 4 that supports the turbine shaft 1 transmitting the rotation of the turbine blade 2 to the compressor blade 3 at two locations, and Rolling bearings are used for both the compressor-side bearing 5. Further, in this turbocharger, the turbine blade 2 is accommodated in the turbine housing 6 through which the high-temperature (for example, about 800 ° C.) exhaust gas G1 discharged from the internal combustion engine flows, and has flowed into the turbine housing 6. The exhaust gas G1 rotates the turbine blade 2 and is discharged from the outlet 61. On the other hand, the compressor blade 3 is accommodated in the compressor housing 7. The rotation of the turbine blade 2 is transmitted to the compressor blade 3 by the turbine shaft 1, and the rotation of the compressor blade 3 compresses the air A1 sucked into the compressor housing 7 from the inlet 71, for example, combustion of the engine Supercharged in rooms. The turbine blade 2 is attached to one end portion of the turbine shaft 1, and the compressor blade 3 is attached to the other end portion of the turbine shaft 1.

  On the other hand, conventionally, a ball bearing for high-speed rotation interposed between a rotating shaft and a casing has been proposed in which a first ball bearing having a small diameter and a second ball bearing having a large diameter are integrated ( Patent Document 1).

Japanese Utility Model Publication No. 62-16825

  By the way, although rolling bearings or ball bearings are excellent in alignment characteristics and rise characteristics at the start of rotation, it has been found that characteristics are deteriorated in a range exceeding a certain number of rotations in high-speed rotation characteristics. On the other hand, a dynamic pressure bearing known to have excellent high-speed rotation characteristics is inferior to a rolling bearing in rising characteristics at the time of starting rotation. Therefore, if the rolling bearings 4 and 5 are used as the bearings as in the conventional turbocharger described with reference to FIG. 4, the service life of the rolling bearings 4 and 5 is increased when the rotational speed of the turbine shaft 1 is increased. May cause problems.

  The present invention has been made in view of the above situation, and satisfies both the rise characteristic required at the time of rotation start and the high speed rotation characteristic required at the time of high speed rotation by combining the rolling bearing element and the dynamic pressure bearing element. It is an object of the present invention to provide a turbocharger that can improve the service life of a bearing by adopting a configuration in which a turbine shaft is supported by a bearing that can be made to operate.

  Another object of the present invention is to provide a turbocharger that does not complicate the process of assembling the bearing while using a combination of a rolling bearing element and a hydrodynamic bearing element as a bearing.

  A turbocharger according to the present invention is a turbocharger in which a turbine shaft that transmits the rotation of a turbine blade to a compressor blade is supported by a bearing. The bearing includes a hydrodynamic bearing element that supports the turbine shaft and an outer periphery of the hydrodynamic bearing element. It is characterized in that it is formed on the side by a rolling bearing element that supports the hydrodynamic bearing element (claim 1).

  With the above configuration, since the bearing load of the hydrodynamic bearing element is larger than that of the rolling bearing element when the turbine shaft starts rotating, the hydrodynamic bearing element rotates together with the turbine shaft and the inner ring of the rolling bearing element. As the rotational speed of the turbine shaft increases, the turbine shaft generates dynamic pressure in the lubricant by the pumping action of the hydrodynamic bearing elements, and starts rotating without contact. And when the rotational speed of the turbine shaft increases and rotates at high speed, and the bearing load of the hydrodynamic bearing element becomes smaller than that of the rolling bearing element, the turbine shaft continues to rotate without contact with the hydrodynamic bearing element. However, the inner ring of the hydrodynamic bearing element or the rolling bearing element stops rotating or rotates at a lower speed than the turbine shaft. Therefore, at the time of rotation start, the characteristics of the rolling bearing element having excellent start-up characteristics at the time of rotation start are utilized, while an excessive load is suppressed on the hydrodynamic bearing element, and at high speed rotation, the high speed rotation characteristics are excellent. While the characteristics of the hydrodynamic bearing element are utilized, an unreasonable load is suppressed from being applied to the rolling bearing element. This improves the service life of the bearing.

  In this invention, it is possible to employ | adopt the structure that the bearing main body of the said dynamic pressure bearing element is shared by the same member as the inner ring | wheel of the said rolling bearing element (Claim 2).

  According to this means, it is not necessary to separately incorporate the dynamic pressure bearing element and the rolling bearing element, and the dynamic pressure bearing element is also incorporated simply by incorporating the rolling bearing element. Although a combination of pressure bearing elements is used, the bearing assembling process can be performed with the same work efficiency as the process of incorporating the rolling bearing into the conventional turbocharger described with reference to FIG. In addition, although a combination of a rolling bearing element and a hydrodynamic bearing element is used as a bearing, there is an advantage that the size of the bearing is the same as that of the rolling bearing element alone and the bearing can be made compact.

  Further, according to the present invention, there is an advantage that the hydrodynamic bearing element is aligned by the excellent alignment effect exhibited by the rolling bearing element.

  As described above, according to the present invention, by the action of the bearing that combines the rolling bearing element and the hydrodynamic bearing element, both the start-up characteristics at the time of rotation start and the high-speed rotation characteristics are satisfied. It is possible to provide a turbocharger having an improved service life of the bearing. Also, in the case where the hydrodynamic bearing element is shared by the same member as the inner ring of the rolling bearing element, the assembly process of the bearing is not complicated, and the assembly work efficiency equivalent to the process of incorporating the conventional turbocharger bearing is ensured. Can be obtained.

  FIG. 1 is a cross-sectional view schematically showing a turbocharger according to a first embodiment of the present invention, and FIG. 2 is an enlarged view of a portion P in FIG. FIG. 3 is a cross-sectional view schematically showing a turbocharger according to another embodiment of the present invention, and FIG. 4 is an enlarged view of a portion Q in FIG.

  In the turbocharger of the first embodiment shown in FIG. 1, two locations of the turbine shaft 1 that transmit the rotation of the turbine blade 2 to the compressor blade 3 are supported by bearings 4 and 5, respectively. Although similar to what has been described, these bearings differ from those described with reference to FIG. 4 in that they are configured by combining the hydrodynamic bearing elements 41, 51 and the rolling bearing elements 45, 55.

  As shown in FIG. 2, the dynamic pressure bearing element 41 of the turbine side bearing 4 forms a clearance S around the turbine shaft 1 for holding a working fluid for generating dynamic pressure when the turbine shaft 1 rotates. A sleeve 42 is provided, and a radial dynamic pressure groove 43 formed on the outer peripheral surface of the turbine shaft 1 is provided. The dynamic pressure bearing element 41 and the sleeve 42 are substantially the same, but the term “dynamic pressure bearing element 41” is used as a general term, and the term “sleeve 42” is used as a specific term (the following dynamics). The same applies to the pressure bearing element 51).

  The radial dynamic pressure groove 43 is formed, for example, in a V shape or a herringbone shape. The radial dynamic pressure groove 43 may be formed on the inner peripheral surface of the sleeve 42. In the hydrodynamic bearing element 41 which is this sleeve, when the rotation of the turbine shaft 1 is stopped, the turbine shaft 1 sinks into the working fluid by its weight and is in line contact or surface contact with the bearing body 42. On the other hand, when the turbine shaft 1 is rotating, the working fluid generates dynamic pressure by the pumping action of the radial dynamic pressure groove 43 so that the working fluid film is held between the turbine shaft 1 and the sleeve 42. Therefore, the turbine shaft 1 rotates without contact with the sleeve 42.

  Further, the rolling bearing element 45 of the turbine side bearing 4 is fixed to the bearing main body 42 of the dynamic pressure bearing element 41 by means such as press fitting, and the inner ring 46 disposed on the outer peripheral side of the dynamic pressure bearing element 41 and the rolling bearing element 45. A moving body 47 and an outer ring 48 are provided, and the centering action inherent to the rolling bearing element 45 is exhibited.

  The same applies to the bearing 5 on the compressor side, 51 is a dynamic pressure bearing element, 52 is a sleeve of the dynamic pressure bearing element 51, 53 is a radial dynamic pressure groove, 56 is an inner ring of the rolling bearing element 55, 57 is a rolling element, and 58 is This is an outer ring of the rolling bearing element 55.

  In addition, the working fluid of the hydrodynamic bearing elements 41 and 51 is held in the bearing chamber 8 in which the bearings 4 and 5 are provided, and this working fluid may be used as a lubricant for the rolling bearing elements 45 and 55. is there.

  In the turbocharger of FIG. 1, when the rotation of the turbine shaft 1 is started, the bearing load of the dynamic pressure bearing elements 41 and 51 is larger than that of the rolling bearing elements 45 and 55. 42 and 52 rotate together with the turbine shaft 1 and the inner rings 46 and 56 of the rolling bearing elements 45 and 55, and then, as the rotational speed of the turbine shaft 1 increases, the turbine shaft 1 becomes the sleeve 42 of the hydrodynamic bearing elements 41 and 51, 52 starts rotating without contact. Then, when the rotational speed of the turbine shaft 1 increases and rotates at a high speed, and the bearing load of the dynamic pressure bearing elements 41 and 51 becomes smaller than that of the rolling bearing elements 45 and 55, the turbine shaft 1 moves accordingly. The rotation continues without contact with the sleeves 42 and 52 of the elements 41 and 51, and the dynamic bearing elements 41 and 51 and the inner rings 46 and 56 of the rolling bearing elements 45 and 55 stop rotating, or from the turbine shaft 1. Will also rotate at low speed. Therefore, at the time of starting rotation, the characteristics of the rolling bearing elements 45 and 55 having excellent rise characteristics at the time of starting rotation are utilized, while an excessive load is suppressed on the dynamic pressure bearing elements 41 and 51, and at the time of high speed rotation. In addition, while the characteristics of the hydrodynamic bearing elements 41 and 51 having excellent high-speed rotation characteristics are utilized, an unreasonable load is suppressed from being applied to the rolling bearing elements 45 and 55. The service life is improved.

  In the turbocharger of this embodiment, the bearings 4 and 5 are a set in which the hydrodynamic bearing elements 41 and 51 and the rolling bearing elements 51 and 55 are fitted in advance to form a unit, and the unit is attached to the turbine shaft 1. If the assembly process is performed, the assembly process is not complicated.

  The turbocharger of the second embodiment shown in FIG. 3 is that the sleeves 42 and 52 of the hydrodynamic bearing elements 41 and 51 are shared by the same members as the inner rings 46 and 56 of the rolling bearing elements 45 and 55. This is different from the embodiment described in FIG.

  With this configuration, when the turbine shaft 1 starts rotating, the bearing load of the dynamic pressure bearing elements 41 and 51 in which the sleeves 42 and 52 are shared by the same members as the inner rings 46 and 56 is the same as that of the rolling bearing elements 45 and 55. Since the sleeves 42 and 52 of the hydrodynamic bearing elements 41 and 51 rotate together with the turbine shaft 1 in the same manner as described in FIG. 1, the turbine shaft 1 increases as the rotational speed of the turbine shaft 1 increases. 1 begins to rotate without contact with the sleeves 42, 52 (inner rings 46, 56) of the hydrodynamic bearing elements 41, 51. Then, when the rotational speed of the turbine shaft 1 increases and rotates at high speed, and the bearing load of the hydrodynamic bearing elements 41 and 51 becomes smaller than that of the rolling bearing elements 45 and 55, the turbine shaft 1 is accordingly hydrodynamic bearing. The rotation continues without contact with the sleeves 42 and 52 (inner rings 46 and 56) of the elements 41 and 51, and the hydrodynamic bearing elements 41 and 51 (inner rings 46 and 56) stop rotating or from the turbine shaft 1. Will also rotate at low speed. Therefore, at the time of starting rotation, the characteristics of the rolling bearing elements 45 and 55 having excellent rise characteristics at the time of starting rotation are utilized, while an excessive load is suppressed on the dynamic pressure bearing elements 41 and 51, and at the time of high speed rotation. In addition, while the characteristics of the hydrodynamic bearing elements 41 and 51 having excellent high-speed rotation characteristics are utilized, an unreasonable load is suppressed from being applied to the rolling bearing elements 45 and 55. The service life is improved.

  In the turbocharger of this embodiment, the bearings 4 and 5 are rolling because the sleeves 42 and 52 of the hydrodynamic bearing elements 41 and 51 are shared by the same members as the inner rings 46 and 56 of the rolling bearing elements 45 and 55. Since the dynamic pressure bearing elements 41 and 51 are also incorporated simply by incorporating the bearing elements 45 and 55, the bearing assembling process is equivalent to the process of incorporating the rolling bearing into the conventional turbocharger described in FIG. It can be done with efficiency.

  By the way, the dynamic pressure bearing elements 41 and 51 are required to have a high accuracy in the mounting angle with respect to the turbine shaft 1, and if the mounting angle is inclined, the original functions of the dynamic pressure bearing elements 41 and 51 are not sufficiently exhibited. However, in each of the embodiments shown in FIG. 1 or FIG. 2, the dynamic pressure bearing elements 41 and 51 are also aligned by the excellent alignment effect exhibited by the rolling bearing elements 45 and 55, so that the dynamic pressure bearing is provided. The mounting accuracy required for the elements 41 and 51 is easily ensured. In particular, in the embodiment shown in FIG. 2, since the bearing bodies 42 and 52 of the dynamic pressure bearing elements 41 and 51 are shared by the same members as the inner rings 46 and 56 of the rolling bearing elements 45 and 55 having the alignment function, this action is achieved. Prominently demonstrated.

1 is a cross-sectional view schematically showing a turbocharger according to a first embodiment of the present invention. It is the P section enlarged view of FIG. 1 which shows the cross section of the turbocharger of the 1st Embodiment of this invention. It is sectional drawing which showed roughly the turbocharger which concerns on the 2nd Embodiment of this invention. It is the Q section enlarged view of Drawing 2 showing the section of the turbocharger of a 2nd embodiment of the present invention. It is sectional drawing which showed the conventional turbocharger roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbine shaft 2 Turbine blade 3 Compressor blade 4,5 Bearing 41,51 Dynamic pressure bearing element 45,55 Rolling bearing element

Claims (2)

In the turbocharger that supports the turbine shaft that transmits the rotation of the turbine blade to the compressor blade with a bearing,
A turbocharger in which the bearing is formed by a hydrodynamic bearing element that supports a turbine shaft and a rolling bearing element that supports the hydrodynamic bearing element on the outer peripheral side of the hydrodynamic bearing element. The turbocharger according to claim 1, wherein a bearing body of the dynamic pressure bearing element is shared by the same member as an inner ring of the rolling bearing element.

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