JP2013002312A - Turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the whirling of a rotary shaft in a bearing of the rotary shaft of a turbocharger.SOLUTION: A turbocharger 1 includes a movable housing 25 that has a cylindrical body annularly surrounding a bush 9 on an outer circumferential side of the bush 9 and is movable in an axial direction, and a drive means 26 for driving the movable housing 25 to relatively displace in the axial direction with respect to the bush 9. Moreover, outer circumferential clearances 11 are formed between an outer circumferential surface of the bush 9 and an inner circumferential surface of the movable housing 25, and oil is supplied to the outer circumferential clearances 11. The outer circumferential clearances 11 change according to a relative position of the movable housing 25 with respect to the bush 9. Therefore, the outer circumferential clearances 11 can be changed according to, for example, whether a possibility that a whirl vibration occurs is high, and thus, the whirling of the rotary shaft 2 can be suppressed.

Description

  The present invention relates to a turbocharger, and more particularly to a bearing structure for a rotating shaft of a turbocharger.

  Conventionally, in a turbocharger rotating at a high speed of several hundred thousand rpm, a so-called floating bush bearing is frequently used as a journal bearing structure of a rotating shaft connecting a turbine impeller and a compressor impeller. In this floating bush bearing, a cylindrical bush is inserted between a housing and a rotating shaft, and oil is supplied to both the inner and outer peripheral sides of the bush to form an oil film. The bush is driven by the oil pressure on the inner peripheral side, is braked by the oil pressure on the outer peripheral side, and rotates at a rotational speed corresponding to the rotational speed of the rotary shaft.

By the way, in a sliding bearing of a rotating shaft that rotates at high speed, it is well known that whirl vibration that is asynchronous with rotation is generated on the rotating shaft by itself, and the rotating shaft swings in a saw-tooth manner.
Therefore, in the floating bush bearing of a turbocharger, various countermeasures have been proposed and known in order to suppress the rotation of the rotating shaft caused by whirl vibration.

For example, according to the turbocharger of Patent Document 1, the bush and the housing are mechanically connected by a support member that is elastically deformable in the axial direction. Thereby, the whirl vibration of the rotating shaft can be attenuated.
Further, according to the turbocharger of Patent Document 2, the bush is divided into a turbine side bush and a compressor side bush, and a clearance is formed on each of the turbine side bush and the compressor side bush on the inner peripheral side and the outer peripheral side.

  And, it is considered that the whirl vibration is mainly caused by the specifications on the compressor side far from the center of gravity of the rotating shaft, and the inner peripheral clearance is set small and the outer peripheral clearance is set large in the compressor bush. Therefore, it is said that the whirl vibration of the rotating shaft can be suppressed.

However, according to the turbocharger of Patent Document 1, the vibration attenuation of the shaft depends on the elastic deformation of the support member, and the support member becomes fatigued by repeated deformation and restoration. For this reason, there exists a possibility that the intensity | strength of a supporting member may fall and a supporting member may be destroyed.
Further, although the turbocharger of Patent Document 2 is effective for suppressing the whirl vibration, when the whirl vibration is not so noticeable, the reverse clearance is caused by the large outer peripheral clearance in the compressor bush. In addition, there is an increased risk that the whirling will occur.

JP 2010-138757 A Japanese Patent No. 4386563

  The present invention has been made to solve the above-described problems, and an object thereof is to make it possible to suppress the rotation of the rotating shaft in the bearing of the rotating shaft of the turbocharger.

[Means of Claim 1]
According to the means of claim 1, the turbocharger includes a bush that supports a rotating shaft that connects a turbine that is rotated by exhaust gas and a compressor that compresses intake air, and a cylinder that annularly surrounds the bush on the outer peripheral side of the bush. A movable housing that is movable in the axial direction and a driving means that drives the movable housing to displace relative to the bush in the axial direction. In addition, a clearance is formed between the outer peripheral surface of the bush and the inner peripheral surface of the movable housing, and oil is supplied. The clearance changes according to the relative position of the movable housing with respect to the bush.

  Thereby, for example, the clearance (outer peripheral clearance) between the outer peripheral surface of the bush and the inner peripheral surface of the movable housing can be changed depending on whether or not there is a high possibility of occurrence of whirl vibration. That is, when there is a high risk of occurrence of whirl vibration, the movable housing can be positioned so that the outer peripheral clearance is increased, thereby reducing the possibility of occurrence of whirling due to whirl vibration.

Further, when the possibility of occurrence of whirl vibration is low, the movable housing is positioned so that the outer peripheral clearance becomes smaller, and the possibility of occurrence of whirling due to the large outer peripheral clearance can be reduced.
For this reason, in the bearing of the rotating shaft of the turbocharger, the swinging of the rotating shaft can be suppressed.

[Means of claim 2]
According to the means of claim 2, the bush is divided into a turbine side bush close to the turbine in the axial direction and a compressor side bush close to the compressor in the axial direction. Further, the clearance is divided into a turbine side clearance formed between the movable housing and the turbine side bush, and a compressor side clearance formed between the movable housing and the compressor side bush.

The turbine-side clearance and the compressor-side clearance change according to the relative positions of the movable housing with respect to the turbine-side bush and the compressor-side bush.
Thereby, since the sliding surface in the bearing of a rotating shaft can be reduced, the reliability with respect to a seizure avoidance can be improved.

[Means of claim 3]
According to the third aspect of the present invention, the inner peripheral surface of the movable housing is provided with concave portions that are recessed toward the outer peripheral side and convex portions that protrude toward the inner peripheral side, alternately in the axial direction. The clearance increases when the outer peripheral surface of the bush faces the concave portion in the radial direction, and decreases when the outer peripheral surface of the bush faces the convex portion in the radial direction.
This means shows one aspect in which the clearance is changed according to the relative position of the movable housing with respect to the bush.

[Means of claim 4]
According to the fourth aspect of the present invention, the step surface connecting the outer peripheral bottom surface of the concave portion and the inner peripheral top surface of the convex portion in the axial direction is inclined with respect to the concave portion and the convex portion adjacent in the axial direction.
Thereby, the possibility that the corners of the bush may interfere with the relative displacement of the movable housing can be reduced.

[Means of claim 5]
According to the fifth aspect of the present invention, oil passages for guiding oil to the clearance are opened on the outer peripheral bottom surface of the concave portion and the inner peripheral top surface of the convex portion, respectively.
Thereby, oil can be reliably supplied to the outer peripheral side clearance.

[Means of claim 6]
According to the means of claim 6, the turbocharger has a shaft rotation number detecting means for detecting the number of rotations of the rotating shaft per unit time (the number of rotations of the rotating shaft), and a detection value by the shaft rotation number detecting means is a predetermined value. And a control unit that operates the driving unit so that the outer peripheral surface of the bush faces the concave portion in the radial direction when within the range.

Since the frequency of the whirl vibration is a numerical value inherent to the shaft system including the rotation axis (hereinafter referred to as the whirl frequency), the whirl vibration is prominent in the range where the rotation speed of the rotation shaft is close to the whirl frequency. Become.
Therefore, in the turbocharger, the rotational speed of the rotating shaft can be detected, and when the detected value of the rotational speed is within a predetermined range including the whirl frequency, the outer peripheral surface of the bush and the concave portion are opposed to each other in the radial direction. The drive means is controlled as follows. That is, when the detected value of the rotational speed is in a range close to the whirl frequency, the outer peripheral clearance is increased so that the whirl vibration can be suppressed.

  This eliminates the need to perform complicated processing such as fast Fourier transform for each control period in order to determine whether or not the whirling vibration is noticeable. It is possible to control the driving means by judging whether or not.

It is a whole block diagram of a turbocharger (Example). It is a principal part block diagram of a turbocharger (Example). It is a disassembled block diagram of a turbocharger (Example). It is a principal part block diagram of the state which the movable housing of the turbocharger moved to the one end side (Example). It is a characteristic view which shows the rotation speed characteristic of a turbocharger (Example).

  The turbocharger according to the embodiment includes a bush that supports a rotating shaft that connects a turbine that is rotated by exhaust gas and a compressor that compresses intake air, and a cylindrical body that annularly surrounds the bush on the outer peripheral side of the bush. And a drive means for driving the movable housing and displacing the bush relative to the bush in the axial direction. In addition, a clearance (outer peripheral clearance) is formed between the outer peripheral surface of the bush and the inner peripheral surface of the movable housing, and oil is supplied, and the clearance changes according to the relative position of the movable housing with respect to the bush. .

  The bush is divided into a turbine side bush close to the turbine in the axial direction and a compressor side bush close to the compressor in the axial direction. Further, the clearance is divided into a turbine side clearance formed between the movable housing and the turbine side bush, and a compressor side clearance formed between the movable housing and the compressor side bush.

  The turbine-side clearance and the compressor-side clearance change according to the relative positions of the movable housing with respect to the turbine-side bush and the compressor-side bush.

In addition, concave portions that are recessed toward the outer peripheral side and convex portions that protrude toward the inner peripheral side are alternately provided in the axial direction on the inner peripheral surface of the movable housing. The clearance increases when the outer peripheral surface of the bush faces the concave portion in the radial direction, and decreases when the outer peripheral surface of the bush faces the convex portion in the radial direction.
In addition, regarding the recessed part and convex part which are adjacent to an axial direction, the step surface which connects the outer peripheral bottom face of a recessed part and the inner peripheral top face of a convex part is inclined. In addition, oil passages for guiding oil to the clearance are opened on the outer peripheral bottom surface of the recess and the inner peripheral top surface of the protrusion, respectively.

  Furthermore, the turbocharger has a shaft rotation number detecting means for detecting the number of rotations of the rotating shaft per unit time (the number of rotations of the rotating shaft), and a value detected by the shaft rotation number detecting means is within a predetermined range. And control means for operating the drive means so that the outer peripheral surface of the bush faces the recess in the radial direction.

[Configuration of Example]
The structure of the turbocharger 1 of an Example is demonstrated based on FIGS. 1-4.
The turbocharger 1 compresses intake air using the energy of exhaust gas exhausted from an internal combustion engine (not shown) and sends it to the internal combustion engine. It aims to reduce the fuel consumption and the harmful components of exhaust gas by allowing the air-fuel mixture exceeding the displacement to be inhaled and combusted.

  The turbocharger 1 includes a turbine 3 that converts heat energy and kinetic energy of exhaust gas into rotational energy of a rotating shaft 2, a compressor 4 that compresses intake air by rotational torque transmitted from the rotating shaft 2, and sends the compressed air to an internal combustion engine. A journal bearing 5 and a thrust bearing 6 for bearing the rotary shaft 2 are provided.

  Here, the turbine 3 is formed by accommodating the impeller 3I so as to be rotatable in the exhaust gas passage 3L of the turbine housing 3H, and the compressor 4 is inserted in the intake air passage 4L of the compressor housing 4H. It is formed by accommodating 4I so as to be rotatable. The rotating shaft 2 connects the impeller 3I and the impeller 4I. That is, the impeller 4I is attached to one end of the rotating shaft 2 in the axial direction by the nut 4N, and the impeller 3I is attached to the other end by welding or the like.

With such a configuration, the turbocharger 1 uses the energy of the exhaust gas to rotate the impeller 3I at high speed, and the impeller 4I is rotationally driven by the rotational torque to compress the intake air and send it to the internal combustion engine. .
Further, the number of rotations per unit time (the number of rotations) of the turbine 3 reaches as high as several hundred thousand rpm, and so-called floating bush bearings are adopted as the journal bearings 5.

  That is, in the journal bearing 5, a cylindrical bush 9 is inserted between the bearing housing 8 and the rotary shaft 2, the clearances 10 and 11 are formed on the inner peripheral side and the outer peripheral side of the bush 9, and oil is supplied. (Hereinafter, the clearances 10 and 11 formed on the inner peripheral side and the outer peripheral side of the bush 9 are referred to as inner peripheral side and outer peripheral side clearances 10 and 11, respectively). . Note that oil is supplied to the outer clearance 11 through an oil passage 12 provided in the bearing housing 8. In addition, oil is supplied from the outer peripheral side clearance 11 to the inner peripheral side clearance 10 through an oil passage 12 provided in the bush 9.

The bush 9 is driven by the hydraulic pressure of the inner peripheral clearance 10, is braked by the hydraulic pressure of the outer peripheral clearance 11, and rotates at a rotational speed corresponding to the rotational speed of the rotary shaft 2.
Here, the bearing housing 8 is disposed between the turbine housing 3H and the compressor housing 4H, and accommodates the bush 9 and the like, and forms inner and outer clearances 10 and 11.

  In the thrust bearing 6, the thrust bearing 15 and the collars 16a and 16b are accommodated in an intermediate housing 14 disposed on one end side of the bearing housing 8, the rotating shaft 2 is passed through the collars 16a and 16b, and the rotating shaft 2 is mounted on the collar 16a. The step portion 2a is in contact with each other. In the thrust bearing 6, oil is supplied to the gap formed by the intermediate housing 14, the thrust bearing 15, the collars 16 a and 16 b, the rotating shaft 2, and the like through the oil passage 12 provided in the bearing housing 8 and the intermediate housing 14. Has been.

In addition, oil leakage prevention mechanisms 18 and 19 for preventing oil leakage to the passages 3L and 4L are provided on the other end side and one end side of the bush 9, respectively.
The oil leakage prevention mechanism 18 is mainly configured by a C-shaped seal ring 20 that seals between the rotary shaft 2 and the bearing housing 8 on the other end side of the rotary shaft 2, and the oil passes through the seal ring 20. It is prevented from leaking to 3L. A spacer 21 is attached to the other end of the bearing housing 8.

  The oil leakage prevention mechanism 19 is mainly composed of a plate 23 that is fitted into the cap 22 and accommodated in the intermediate housing 14. Here, the plate 23 is provided so that oil supplied to various gaps in the thrust bearing 6 can be returned to the bearing housing 8.

  In the intermediate housing 14, the circlip 23a is accommodated on the most end side, and the thrust bearing 15, the cap 22 and the plate 23 are urged to the other end side by the circlip 23a. An O-ring is appropriately disposed between the cap 22 and the intermediate housing 14, between the compressor housing 4H and the intermediate housing 14, and between the bearing housing 8 and the intermediate housing 14.

The turbocharger 1 has the following configuration in order to suppress the swing of the rotating shaft 2.
That is, the turbocharger 1 includes a bush 9 that supports the rotating shaft 2, a cylindrical body that annularly surrounds the bush 9 on the outer peripheral side of the bush 9, and a movable housing 25 that is movable in the axial direction. Drive means 26 that is driven to displace relative to the bush 9 in the axial direction, shaft rotation speed detection means 27 that detects the rotation speed of the rotary shaft 2, and drive according to a detection value by the shaft rotation speed detection means 27. And control means 28 for operating the means 26.

  The bush 9 is divided into a turbine side bush 9T close to the turbine 3 in the axial direction and a compressor side bush 9C close to the compressor 4 in the axial direction. The turbine side and compressor side bushes 9T and 9C are Separated in direction.

  The inner circumferential clearance 10 includes a turbine-side clearance 10T formed between the movable housing 25 and the turbine-side bush 9T, and a compressor-side clearance 10C formed between the movable housing 25 and the compressor-side bush 9C. Similarly, the outer peripheral side clearance 11 is also a turbine side clearance 11T formed between the movable housing 25 and the turbine side bush 9T, and a compressor side formed between the movable housing 25 and the compressor side bush 9C. It is divided into clearance 11C.

  The movable housing 25 is a part of the bearing housing 8 and is guided from the outer peripheral side by a housing body 8A that forms the body of the bearing housing 8 so as to be movable in the axial direction. In addition, the inner peripheral surface of the movable housing 25 is provided with concave portions 31T and 31C that are recessed toward the outer peripheral side and convex portions 32T and 32C that protrude toward the inner peripheral side, and the convex portions 32C that extend from one end to the other end in the axial direction. The concave portion 31C, the convex portion 32T, and the concave portion 31T are provided in this order.

  Here, the outer peripheral bottom surface 33 of the concave portions 31T and 31C and the inner peripheral top surface 34 of the convex portions 32T and 32C are provided as a cylindrical surface concentric with the movable housing 25 itself, and the outer peripheral bottom surface 33 of the concave portion 31T on the other axial end side. And the outer peripheral bottom surface 33 of the concave portion 31C on one axial end side have the same diameter. The inner peripheral top surface 34 of the convex portion 32T on the other axial end side and the inner peripheral top surface 34 of the convex portion 32C on the one axial end side have the same diameter.

  As described above, the turbine side and compressor side clearances 11T and 11C change in accordance with the relative positions of the movable housing 25 with respect to the turbine side and the compressor side bushes 9T and 9C, respectively. That is, the turbine-side and compressor-side clearances 11T and 11C become larger when the outer peripheral surfaces of the turbine-side and compressor-side bushes 9T and 9C are opposed to the outer peripheral bottom surfaces 33 of the recesses 31T and 31C in the radial direction, respectively (see FIG. 4). ), The outer peripheral surfaces of the turbine-side and compressor-side bushes 9T, 9C are made smaller by facing the inner peripheral top surfaces 34 of the convex portions 32T, 32C in the radial direction (see FIGS. 1 and 2).

  In addition, regarding the concave portion 31T and the convex portion 32T adjacent in the axial direction, the step surface 35 connecting the outer peripheral bottom surface 33 of the concave portion 31T and the inner peripheral top surface 34 of the convex portion 32T in the axial direction is inclined. Similarly, the stepped surface 35 that connects the outer peripheral bottom surface 33 of the concave portion 31C and the inner peripheral top surface 34 of the convex portion 32C in the axial direction is also inclined.

An oil passage 12 that guides oil to the outer peripheral side clearance 11 is opened in the outer peripheral bottom surface 33 of the concave portions 31T and 31C and the inner peripheral top surface 34 of the convex portions 32T and 32C.
Here, the configuration of the oil passage 12 in the journal bearing 5 will be described.

  First, the body housing of the bearing housing 8 is provided with an oil supply port 37 and a discharge port 38, and the oil passage 12 is supplied with oil from the supply port 37 to the journal and thrust bearings 5 and 6. It is configured to be discharged from the discharge port 38. The supply port 37 is supplied with oil passage 12a for supplying oil to the inner peripheral side on the other end, outer clearances 10T and 11T, and to the inner peripheral side and outer clearances 10C and 11C on one end side. An oil passage 12b for supplying oil to the thrust bearing 6 and an oil passage 12c for supplying oil to the thrust bearing 6 are connected.

In the movable housing 25, oil passages 12d, 12e, 12f, and 12g penetrating in the radial direction are sequentially provided at the same position in the circumferential direction from the other end toward the one end.
Here, the oil passages 12d and 12f open to the outer peripheral bottom surfaces 33 of the recesses 31T and 31C, respectively. The openings on the outer peripheral surfaces of the oil passages 12d and 12f face the openings of the oil passages 12a and 12b in the radial direction when the movable housing 25 is displaced to one end side and the outer peripheral clearance 11 is large (see FIG. 4). The oil flows into the oil passages 12d and 12f from the oil passages 12a and 12b, and is supplied to the outer peripheral side clearances 11T and 11C.

  The oil passages 12e and 12g are opened on the inner peripheral top surfaces 34 of the convex portions 32T and 32C. The openings on the outer peripheral surfaces of the oil passages 12e and 12g are opposed to the openings of the oil passages 12a and 12b in the radial direction when the movable housing 25 is displaced to the other end side and the outer peripheral clearance 11 is small (FIG. 1, FIG. 2), the oil flows from the oil passages 12a and 12b into the oil passages 12e and 12g and is supplied to the outer circumferential clearances 11T and 11C.

  Further, oil passages 12h and 12i that penetrate in the radial direction are provided in the turbine side and compressor side bushes 9T and 9C, respectively, and from the outer circumference side clearances 11T and 11C through the oil passages 12h and 12i, the inner circumference side clearance 10T. Oil is supplied to 10C.

  The turbine side and compressor side bushes 9T and 9C are respectively provided with oil passages 12j and 12k penetrating in the radial direction on the side symmetrical to the oil passages 12h and 12i with respect to the rotating shaft 2. The oil is discharged from the inner peripheral side clearances 10T and 10C to the outer peripheral side clearances 11T and 11C through the oil passages 12j and 12k. The movable housing 25 is provided with an oil passage 12m penetrating in the radial direction on the side symmetrical to the oil passages 12d to 12g with the rotation shaft 2 interposed therebetween, and the outer clearance 11T through the oil passage 12m. The oil is discharged from 11C toward the discharge port 38.

  The oil flowing into the oil passage 12c is supplied to various gaps in the thrust bearing 6 through the oil passage 12 provided in the intermediate housing 14 and the thrust bearing 15 and returned to the bearing housing 8 by the plate 23. To the discharge port 38.

The driving means 26 includes, for example, a known driving force generator 40 such as a hydraulic piston, and an arm 41 that moves forward and backward in the axial direction by the driving force generated by the driving force generator 40, and the tip of the arm 41 is movable. It is fixed to the housing 25. Thereby, the drive means 26 transmits the drive force of the drive force generator 40 to the movable housing 25 via the arm 41, and drives the movable housing 25 in the axial direction.
The shaft rotation speed detection means 27 is, for example, a known rotation speed sensor of an electromagnetic pickup type.

  The control means 28 is a microcomputer having a well-known structure configured to include functions of a CPU for performing control processing and arithmetic processing, a storage device for storing various programs and various data, an input circuit, an output circuit, and the like. The operation of the driving means 26 is controlled in accordance with detection values input from various detection means such as the detection means 27, and the movable housing 25 is moved to a target position.

Hereinafter, position control of the movable housing 25 by the control means 28 will be described.
The position of the movable housing 25 is controlled with respect to the turbine side and the compressor side bushes 9T and 9C so that the size of the outer peripheral side clearance 11 changes according to the value detected by the shaft rotation number detecting means 27. It is displaced relative to the direction.

  That is, the control means 28 considers that there is a high risk of occurrence of whirl vibration on the rotary shaft 2 when the value detected by the shaft rotational speed detection means 27 is within the predetermined range α (see FIG. 5). The movable housing 25 is displaced to a position where the clearances 11T and 11C are increased, thereby reducing the possibility of occurrence of swinging due to whirl vibration. Further, when the value detected by the shaft rotational speed detecting means 27 is outside the range α, the control means 28 regards that the possibility that the whirl vibration is generated in the rotating shaft 2 is low, and the position where the outer peripheral side clearances 11T and 11C become small. The movable housing 25 is displaced to reduce the possibility of the occurrence of run-out due to the large outer peripheral clearances 11T and 11C.

  That is, when the detected value by the shaft rotation number detecting means 27 is within the range α, the control means 28 is configured so that the outer peripheral surface of the bush 9 faces the outer peripheral bottom surface 33 of the recesses 31T and 31C in the radial direction. Is displaced to one end side (see FIG. 4), and when the value detected by the shaft rotational speed detection means 27 is outside the range α, the outer peripheral surface of the bush 9 is the diameter of the inner peripheral top surface 34 of the convex portions 32T and 32C. The movable housing 25 is displaced to the other end side so as to face each other (see FIGS. 1 and 2).

  Here, since the frequency of the whirl vibration is a numerical value unique to the shaft system including the rotation shaft 2 (hereinafter referred to as the whirl frequency), the rotation frequency of the rotation shaft 2 is changed to the whirl frequency. It becomes noticeable in the near range.

  That is, when the rotational speed of the rotating shaft 2 substantially matches the whirl frequency, for example, the rotational speed characteristics obtained by Fourier transforming the time-series data related to the rotational angle of the rotating shaft 2 are the characteristics shown in FIG. As indicated by the line La, a large peak is exhibited at the whirl frequency. Further, when the rotational speed of the rotary shaft 2 is a numerical value considerably larger than the whirl frequency (hereinafter referred to as a significant large rotational speed), the same rotational speed characteristic is indicated by a special line Lb in FIG. As described above, although the peak is shown at the significant rotation speed, the height of the peak is not as high as the peak at the whirl frequency of the characteristic line La.

  Therefore, for example, when the range α is set to have the same rotation speed width on the + side and the − side with respect to the whirl frequency, and the detection value by the shaft rotation speed detection means 27 is within the range α, the rotation shaft 2 Is considered to have a high possibility of occurrence of whirl vibration, and the risk of occurrence of whirling due to whirl vibration is reduced. Further, when the value detected by the shaft rotational speed detection means 27 is outside the range α, it is considered that there is a low risk of occurrence of whirl vibration in the rotary shaft 2 and there is a risk of occurrence of whirling due to the large outer peripheral clearance 11. Reduce.

[Effects of Examples]
The turbocharger 1 according to the embodiment includes a bush 9 that supports a rotating shaft 2, a cylindrical body that annularly surrounds the bush 9 on the outer peripheral side of the bush 9, and a movable housing 25 that is movable in the axial direction. And a driving means 26 for moving the shaft relative to the bush 9 in the axial direction. Further, an outer peripheral clearance 11 is formed between the outer peripheral surface of the bush 9 and the inner peripheral surface of the movable housing 25, and oil is supplied. The outer peripheral clearance 11 is positioned relative to the bush 9 of the movable housing 25. It changes according to.

  Thereby, the outer peripheral side clearance 11 can be changed depending on whether or not there is a high possibility of occurrence of whirl vibration. That is, when there is a high risk of occurrence of whirl vibration, the movable housing 25 can be positioned so that the outer peripheral clearance 11 is increased, thereby reducing the possibility of occurrence of whirling due to whirl vibration.

Further, when the possibility of occurrence of whirl vibration is low, the movable housing 25 is positioned so that the outer peripheral side clearance 11 becomes smaller, so that the possibility of occurrence of swinging due to the larger outer peripheral side clearance 11 can be reduced. it can.
For this reason, in the journal bearing 5 of the turbocharger 1, it is possible to suppress the swing of the rotating shaft 2.

  The bush 9 is divided into a turbine-side bush 9T close to the turbine 3 in the axial direction and a compressor-side bush 9C close to the compressor 4 in the axial direction, and the outer peripheral clearance 11 has a movable housing 25 and a turbine-side bush 9T. And a compressor side clearance 11C formed between the movable housing 25 and the compressor bushing 9C.

The turbine-side clearance 11T and the compressor-side clearance 11C change according to the relative positions of the movable housing 25 with respect to the turbine-side bush 9T and the compressor-side bush 9C.
Thereby, since the sliding surface in the journal bearing 5 can be reduced, the reliability with respect to a seizure avoidance can be improved.

In addition, regarding the concave portions 31T and 31C and the convex portions 32T and 32C adjacent in the movable housing 25 in the axial direction, the outer peripheral bottom surface 33 of the concave portions 31T and 31C and the inner peripheral top surface 34 of the convex portions 32T and 32C are connected in the axial direction. The step surface 35 is inclined.
Thereby, the possibility that the corners of the bush 9 interfere with the displacement of the movable housing 25 can be reduced.

Also, oil passages 12d to 12g are opened on the outer peripheral bottom surface 33 of the recess 31T, the inner peripheral top surface 34 of the convex portion 32T, the outer peripheral bottom surface 33 of the concave portion 31C and the inner peripheral top surface 34 of the convex portion 32C, respectively. The oil passages 12d and 12e and the oil passages 12f and 12g guide oil to the turbine side and compressor side clearances 11T and 11C, respectively.
Thereby, oil can be reliably supplied to the turbine side and compressor side clearances 11T and 11C.

Further, the turbocharger 1 detects the rotation speed of the bush 9 when the rotation speed detection means 27 for detecting the rotation speed of the rotation shaft 2 and the value detected by the rotation speed detection means 27 is within the range α including the whirl frequency. And a control means 28 for operating the driving means 26 so that the outer peripheral surface faces the recesses 31T and 31C in the radial direction.
The whirl vibration becomes prominent when the rotation speed of the rotary shaft 2 is close to the whirl vibration frequency.
Therefore, when the detected value of the rotational speed of the rotating shaft 2 is within the range α, the turbine side and compressor side clearances 11T and 11C are increased so that the whirl vibration can be suppressed.

  This eliminates the need to perform complicated processing such as fast Fourier transform for each control period in order to determine whether or not the whirling vibration is noticeable. It can be determined whether or not the driving means 26 can be controlled.

[Modification]
The aspect of the turbocharger 1 is not limited to an Example, Various modifications can be considered.
For example, according to the turbocharger 1 of the embodiment, the bush 9 is divided into the turbine side and the compressor side bushes 9T and 9C, and the outer peripheral side clearance 11 is also divided into the turbine side and the compressor side clearances 11T and 11C. One bush 9 that is not divided between the turbine side and the compressor side may be used, and the outer peripheral clearance 11 may be one without being divided into the turbine side and the compressor side.

  Further, according to the turbocharger 1 of the embodiment, the control means 28 is a drive means so that the outer peripheral clearance 11 changes depending on whether or not the value detected by the shaft rotation speed detection means 27 is within the range α. 26, for example, Fourier transform is performed for each control period based on time-series data related to the rotation angle of the rotating shaft 2 to obtain a rotation speed characteristic, and the numerical value of the vibration level at the whirl frequency exceeds the threshold value. The driving means 26 may be operated based on whether or not there is.

DESCRIPTION OF SYMBOLS 1 Turbocharger 2 Rotating shaft 3 Turbine 4 Compressor 9 Bush 9T Turbine side bush 9C Compressor side bush 11 Outer peripheral side clearance (clearance)
11T Turbine-side clearance 11C Compressor-side clearance 12, 12d to 12g Oil passage 25 Movable housing 26 Drive means 27 Shaft rotational speed detection means 28 Control means 31T, 31C Concavity 32T, 32C Convex portion 33 Outer peripheral bottom surface 34 Inner peripheral top surface 35 Step surface α range (predetermined range)

Claims (6)

A bush that supports a rotating shaft that connects a turbine that is rotated by exhaust gas and a compressor that compresses intake air; and
A movable housing that annularly surrounds the bush on the outer peripheral side of the bush and is movable in the axial direction;
Driving means for driving the movable housing to displace relative to the bush in the axial direction;
A clearance is formed between the outer peripheral surface of the bush and the inner peripheral surface of the movable housing, and oil is supplied,
The turbocharger, wherein the clearance changes according to a relative position of the movable housing with respect to the bush. The turbocharger according to claim 1, wherein
The bush is divided into a turbine side bush close to the turbine in the axial direction and a compressor side bush close to the compressor in the axial direction,
The clearance is divided into a turbine side clearance formed between the movable housing and the turbine side bush, and a compressor side clearance formed between the movable housing and the compressor side bush,
The turbocharger, wherein the turbine side clearance and the compressor side clearance change according to a relative position of the movable housing with respect to the turbine side bush and the compressor side bush. In the turbocharger according to claim 1 or 2,
On the inner peripheral surface of the movable housing, concave portions that are recessed toward the outer peripheral side and convex portions that protrude toward the inner peripheral side are alternately provided in the axial direction,
The turbocharger is characterized in that the clearance increases when the outer peripheral surface of the bush faces the concave portion in the radial direction and decreases when the outer peripheral surface of the bush faces the convex portion in the radial direction. The turbocharger according to claim 3, wherein
A turbocharger characterized in that, with respect to the concave portion and the convex portion adjacent to each other in the axial direction, a step surface connecting the outer peripheral bottom surface of the concave portion and the inner peripheral top surface of the convex portion in the axial direction is inclined. In the turbocharger according to claim 3 or 4,
The turbocharger, wherein oil passages for guiding oil to the clearance are opened on the outer peripheral bottom surface of the concave portion and the inner peripheral top surface of the convex portion, respectively. In the turbocharger as described in any one of Claim 3 thru | or 5,
Shaft rotation number detecting means for detecting the number of rotations per unit time of the rotation shaft;
A turbocharger comprising: a control unit that operates the driving unit so that an outer peripheral surface of the bush is opposed to the concave portion in a radial direction when a value detected by the shaft rotation number detection unit is within a predetermined range.

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