JP2007100644A - Bearing device for turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a turbocharger capable of dynamically inhibiting self-excited vibration. <P>SOLUTION: A bearing device 20 for a turbocharger provided with a compressor side bearing 8 and a turbine side bearing 9 as bearings of a rotary shaft 5 connecting a compressor and a turbine is provided with a bearing rotation speed control means controlling rotation speed of the compressor side bearing 8 and the turbine side bearing 9. The bearing rotation speed control means controls each rotation speed based on an operation condition of the engine and/or an operation condition of the turbocharger. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a turbocharger bearing device including a compressor side bearing and a turbine side bearing.

  The turbocharger increases the pressure of the air-fuel mixture sucked into the engine by rotating the turbine with exhaust gas and rotating a compressor connected to the turbine via a shaft. Since the shaft of the turbocharger rotates at an ultra-high speed, generally, all-floating type bearings in which the bearing itself also rotates are provided on the turbine side and the compressor side. This all-floating bearing is filled with oil in the clearance (clearance) between the inner diameter side of the bearing and the shaft and between the outer diameter side of the bearing and the bearing housing, and rotates freely between the shaft and the bearing housing. be able to. Further, since the oil film is formed in the gap with the fully floating bearing, the shaft rotates in a floating state with respect to the fully floating bearing.

When a fully floating bearing is used, a self-excited vibration (oil whirl phenomenon) that the shaft touches while rotating may occur, and noise is generated by this self-excited vibration. In order to suppress this self-excited vibration, there is a configuration in which the inner diameter side clearance and the outer diameter side clearance or the outer diameter width and the inner diameter width are configured with different bearing specifications for the turbine side bearing and the compressor side bearing (see Patent Document 1). ).
JP 2002-138846 A

  As described above, when self-excited vibration is suppressed only by the bearing specifications of each floating type bearing, the means for suppressing the self-excited vibration is fixed, so that self-excited vibration occurs when various conditions related to the turbocharger change. there's a possibility that. For example, while the vehicle is running, the operating state of the engine and the operating state of the turbocharger are constantly changing due to the accelerator operation of the driver. Under certain operating conditions due to these changes, the damping effect of the turbine-side bearing may decrease, or the oil film rigidity balance between the shaft and the compressor-side bearing may become unstable, and self-excited vibration cannot be suppressed. There is sex. Furthermore, since two types of bearings are required, the number of components increases because the components cannot be shared, and an increase in manufacturing costs such as prevention of erroneous assembly accompanying the increase in types leads.

  Therefore, an object of the present invention is to provide a turbocharger bearing device capable of dynamically suppressing self-excited vibration.

  A turbocharger bearing device according to the present invention is a turbocharger bearing device including a compressor side bearing and a turbine side bearing as bearings of a rotating shaft connecting a compressor and a turbine, and each rotation of the compressor side bearing and the turbine side bearing. Bearing rotational speed control means for controlling the number is provided, and the bearing rotational speed control means controls each rotational speed based on engine operating conditions and / or turbocharger operating conditions.

  In a turbocharger bearing device, a rotating shaft connecting a compressor and a turbine is rotatably supported by a compressor side bearing and a turbine side bearing. In this bearing device, the engine operating conditions (for example, engine speed, engine torque, engine load (throttle opening, etc.)) and / or turbocharger operating conditions (for example, compressor speed, The rotation speed of the compressor side bearing and the rotation speed of the turbine side bearing are respectively controlled based on the turbine rotation speed and the supercharging pressure. Thus, by controlling the rotation speed of the compressor side bearing and the rotation speed of the turbine side bearing, it is possible to change the oil film rigidity on the compressor side and the oil film rigidity on the turbine side, respectively. The self-excited vibration of the rotating shaft is affected by the instability of the oil film rigidity balance between the rotating shaft and each bearing. Therefore, in the bearing device, the rotational speed of the compressor-side bearing and the rotational speed of the turbine-side bearing are adjusted so as to suppress self-excited vibration according to the operating conditions of the engine and the operating conditions of the turbocharger. Thus, in this bearing device, even when various conditions relating to the turbocharger change, self-excited vibration can be suppressed dynamically, and noise can be suppressed. Further, in this bearing device, since self-excited vibration can be suppressed regardless of the bearing specifications of the compressor side bearing and the turbine side bearing, it is possible to use the compressor side bearing and the turbine side bearing having the same bearing specifications. Yes, parts can be shared, and the ease of assembly during manufacturing is improved.

  In the turbocharger bearing device of the present invention, the bearing rotation speed control means supplies a compressor-side oil passage that supplies oil that presses the compressor-side bearing toward the compressor, and supplies oil that presses the turbine-side bearing toward the turbine. Actuator driving based on turbine-side oil passages, valves for adjusting the opening degree of compressor-side oil passages and turbine-side oil passages, actuators for opening and closing the valves, and engine operating conditions and / or turbocharger operating conditions And a control unit for controlling.

  In this turbocharger bearing device, the controller controls the rotational speed of the compressor side bearing and / or the rotational speed of the turbine side bearing in order to suppress self-excited vibration based on the operating conditions of the engine or / and the operating conditions of the turbocharger. When it is determined that it is necessary to change the opening of the compressor side oil passage and / or the turbine side oil passage, the drive of the actuator is controlled. The opening of each oil passage may be adjusted in two stages of fully open / closed (and thus increase / decrease the number of rotations of the bearing), or in several stages from fully closed to fully open. The opening degree may be set and adjusted to each opening degree (and thus the rotational speed of the bearing may be increased or decreased in stages). When each opening degree of the compressor side oil passage and / or the turbine side oil passage is increased, oil is supplied from the compressor side oil passage and / or the turbine side oil passage to the compressor side bearing and / or the turbine side bearing. Is pushed to the compressor side and / or the turbine side bearing is pushed to the turbine side. As a result, the compressor side bearing is pressed against the compressor member and dragged by the rotation of the compressor to increase the rotation speed, and / or the turbine side bearing is pressed against the turbine member and dragged by the rotation of the turbine member. The rotational speed increases. On the contrary, when each opening degree of a compressor side oil path and / or a turbine side oil path is made small, the rotation speed of a compressor side bearing will decrease and / or the rotation speed of a turbine side bearing will decrease. Thus, in this bearing device, the rotational speed of each bearing can be controlled by a simple configuration in which each bearing is pressed by oil.

  According to the present invention, self-excited vibration can be suppressed dynamically by controlling the rotation speed of each bearing.

  Embodiments of a bearing device for a turbocharger according to the present invention will be described below with reference to the drawings.

  In the present embodiment, the turbocharger bearing device according to the present invention is applied to a turbocharger bearing device that is mounted on an automobile and includes a fully floating bearing with the same bearing specifications on the compressor side and the turbine side. In the bearing device according to the present embodiment, in order to suppress self-excited vibration, the rotational speed of each fully floating bearing is controlled by ejecting oil to each fully floating bearing. In this embodiment, there are two embodiments, the first embodiment is a basic form, and the second embodiment is a form in which a spacer for suppressing self-excited vibration is further provided in the basic form. Note that the basic configuration of the turbocharger 1 is common between the first embodiment and the second embodiment, and a partial configuration of the bearing device is different.

  With reference to FIG.1 and FIG.2, the turbocharger 1 which concerns on this Embodiment is demonstrated. FIG. 1 is a front sectional view of a turbocharger according to the present embodiment. FIG. 2 is a front sectional view of the bearing device for the turbocharger according to the first embodiment.

  In the turbocharger 1, a compressor housing 2 and a turbine housing 3 are integrally formed via a bearing housing 4. A shaft 5 is rotatably housed in the bearing housing 4. A compressor 6 is rotatably housed in the compressor housing 2, and the compressor 6 is attached to one end of the shaft 5 with a nut 6 a. A turbine 7 is rotatably housed in the turbine housing 3, and the turbine 7 is attached to the other end of the shaft 5 by welding or the like.

  The shaft 5 is rotatably supported by a compressor-side fully floating bearing 8 disposed on the compressor side and a turbine-side fully floating bearing 9 disposed on the turbine side. Each of the bearings 8 and 9 is inserted with a slight gap (outer diameter clearance) between the inner surface of the storage portion 4 a formed in the bearing housing 4. The shaft 5 is inserted with a slight gap (inner diameter clearance) between the inner peripheral surfaces of the bearings 8 and 9. A spacer 10 is disposed between the compressor side fully floating bearing 8 and the turbine side fully floating bearing 9. The spacer 10 has a cylindrical shape and is a spacer for positioning the two bearings 8 and 9. The shaft 5 is provided with a thrust collar 14 on the compressor side, and axial movement is restricted by a thrust bearing 15.

  A main oil passage 11 is formed in the bearing housing 4. Lubricating and cooling oil is sent to the main oil passage 11 from an oil supply source (not shown). Further, in the bearing housing 4, two supply oil passages 12 and 13 are formed between the main oil passage 11 and the storage portion 4 a. The supply oil passage 12 is an oil passage that supplies oil to the vicinity of the compressor-side fully floating bearing 8, and the supply oil passage 13 is an oil passage that supplies oil to the vicinity of the turbine-side fully floating bearing 9. Each of the bearings 8 and 9 is provided with a plurality of oil holes 8a and 9a penetrating the inner surface side and the outer surface side at the center thereof. The spacer 10 is provided with a plurality of oil holes 10a penetrating the inner surface side and the outer surface side at the center thereof.

  The oil sent to the main oil passage 11 is supplied to the bearings 8 and 9 of the storage portion 4a and the outer surface side of the spacer 10 (gap with the storage portion 4a) via the supply oil passages 12 and 13, respectively. The oil is supplied to the inner surfaces of the bearings 8 and 9 and the spacer 10 (the gap with the shaft 5) through the oil holes 8a, 9a and 10a. An oil film is formed in the gap between each of the bearings 8 and 9 and the storage portion 4a and the gap between each of the bearings 8 and 9 and the shaft 5, and a double oil film is formed on the bearings 8 and 9. By these oil films, the shaft 5 rotates while floating on the bearings 8 and 9. The bearings 8 and 9 are dragged by the rotation of the shaft 5 through the oil film, and are rotated at a rotation speed of 20 to 30% with respect to the rotation speed of the shaft 5.

  Here, the main factor of the occurrence of self-excited vibration in the turbocharger will be described using the Sommerfeld number S. The Sommerfeld number S deals with the oil film stability of a sliding bearing lubricated with oil or the like, and is a dimensionless number for evaluating the lubrication state between the sliding bearing and the shaft. The physical interpretation of the Sommerfeld number S is an image of the ratio of the viscous force (supporting capacity) of the oil to the load applied to the bearing, and is expressed by equation (1).

  The Sommerfeld number S is determined for each of the inner oil film and the outer oil film of the bearing, and is determined for each bearing. In the case of the inner oil film, the diameter clearance in the equation (1) is the inner diameter clearance of the bearing, the shaft diameter is the diameter of the shaft, and the rotation speed is the rotation speed of the shaft + the rotation speed of the bearing. In the case of the outer oil film, the diameter clearance in the equation (1) is the outer diameter clearance of the bearing, the shaft diameter is the outer diameter of the bearing, and the rotation speed is the rotation speed of the bearing.

  When the Sommerfeld number S is large, the margin ratio of the oil support capability with respect to the load is increased, the eccentricity of the shaft is decreased, and the shaft is difficult to contact the bearing (oil film breakage is difficult to occur). However, in this case, the instability of the oil film rigidity, which causes self-excited vibration, also increases, and self-excited vibration is likely to occur. Therefore, basically, the occurrence of self-excited vibration can be suppressed by reducing the Sommerfeld number S. As can be seen from Equation (1), the higher the rotational speed of the bearing in the inner oil film or the outer oil film, the larger the Sommerfeld number S, and the more likely self-excited vibration is generated. Thus, the self-excited vibration is affected by the rotation speed of the bearing (and consequently the oil film rigidity). The self-excited vibration is not determined only by the Sommerfeld number S, but the oil film rigidity unbalance between the turbine and compressor bearings, the oil film rigidity unbalance between the inside and outside of the bearing, and the shaft unbalance. The balance amount and the bending resonance frequency of the shaft are also factors.

  The bearing device 20 of the turbocharger 1 according to the first embodiment will be described with reference to FIGS. FIG. 3 is a configuration diagram of a control system of the turbocharger bearing device according to the present embodiment.

  The bearing device 20 includes fully floating bearings 8 and 9 and supports the shaft 5 in a freely rotatable manner. In particular, the bearing device 20 controls the rotational speeds of the bearings 8 and 9 in order to suppress the self-excited vibration of the shaft 5. In the bearing device 20, oil is ejected to the bearings 8 and 9 in order to control the rotational speed of the bearings 8 and 9. For this purpose, the bearing device 20 includes a connection oil passage 21, a compressor-side bearing adjustment oil passage 22, a turbine-side bearing adjustment oil passage, in addition to a mechanism for rotatably supporting the shaft 5 such as the fully floating bearings 8 and 9. 23, an on-off valve 24, an actuator 25, an engine speed sensor 26, an engine load sensor 27, and an ECU [Electronic Control Unit] 28.

  In the bearing housing 4, a connection oil passage 21 is formed between the main oil passage 11 and the on-off valve 24. The connection oil passage 21 is an oil passage that guides the oil in the main oil passage 11 to the on-off valve 24. In the bearing housing 4, a compressor-side bearing adjustment oil passage 22 and a turbine-side bearing adjustment oil passage 23 are formed between the on-off valve 24 and the storage portion 4 a. The compressor-side bearing adjustment oil passage 22 opens near the contact between the compressor-side fully floating bearing 8 and the spacer 10, and is an oil that ejects oil toward the end surface of the compressor-side fully floating bearing 8 on the turbine side. Road. The turbine-side bearing adjustment oil passage 23 opens near the contact between the turbine-side fully floating bearing 9 and the spacer 10, and the oil that jets oil toward the compressor-side end surface of the turbine-side fully floating bearing 9. Road.

  The on-off valve 24 is disposed between the main oil passage 11 in the bearing housing 4 and the storage portion 4 a and in the vicinity of the center between the compressor-side fully floating bearing 8 and the turbine-side fully floating bearing 9. The on-off valve 24 has one inlet and two outlets, the connection oil passage 21 is connected to the inlet, the compressor side bearing adjustment oil passage 22 is connected to one outlet, and the turbine side bearing adjustment is connected to the other outlet. It is connected to the oil passage 23. The on-off valve 24 includes two valve portions. The open / close of the first valve portion allows the connection oil passage 21 and the compressor-side bearing adjustment oil passage 22 to communicate with each other, and the opening / closing of the second valve portion. By closing, the connecting oil passage 21 and the turbine side bearing adjustment oil passage 23 are communicated / blocked.

  The actuator 25 is an actuator that opens and closes the two valve portions of the on-off valve 24. The engine speed sensor 26 is a sensor that detects the engine speed, and transmits the detected engine speed to the ECU 28. The engine load sensor 27 is a sensor that detects an engine load (for example, throttle opening), and transmits the detected engine load to the ECU 28.

  The ECU 28 includes a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like, and functions as a control unit of the bearing device 20. The ECU 28 takes in the detected values from the sensors 26 and 27, performs bearing rotation speed control based on the detected values, and controls the driving of the actuator.

  The ECU 28 holds an engine speed-engine load map and a bearing speed control map. The engine speed-engine load map is a map set in advance by a vehicle running experiment, and a region in which self-excited vibration is likely to occur is set according to the relationship between the engine speed and the engine load. The bearing speed control map is a map set in advance by a vehicle running experiment, and is used to suppress the self-excited vibration in a region where the self-excited vibration is likely to occur due to the relationship between the engine speed and the engine load. Whether or not the rotational speed of the compressor-side fully floating bearing 8 and the rotational speed of the turbine-side fully floating bearing 9 are increased is set for each value of the engine load.

  The ECU 28 refers to the engine speed-engine load map at regular time intervals to determine whether the relationship between the taken-in engine speed and engine load is in a region where self-excited vibration is likely to occur. When the ECU 28 is in a region where self-excited vibration is likely to occur, the ECU 28 refers to the bearing speed control map, and in order to suppress the self-excited vibration, the values of the incorporated engine speed and engine load are set to the compressor. Only the rotational speed of the side fully floating bearing 8 is increased, only the rotational speed of the turbine side fully floating bearing 9 is increased, or the rotational speed of the compressor side fully floating bearing 8 and the turbine side fully floating bearing It is determined whether the number of rotations 9 is increased.

  When it is determined that only the rotational speed of the compressor side fully floating bearing 8 is to be increased, the ECU 28 transmits a control signal indicating “open first valve portion of the on-off valve 24” to the actuator 25. When it is determined that only the rotational speed of the turbine-side fully floating bearing 9 is increased, the ECU 28 transmits a control signal indicating “open the second valve portion of the on-off valve 24” to the actuator 25. When it is determined that the rotation speed of the compressor-side fully floating bearing 8 and the rotation speed of the turbine-side fully floating bearing 9 are to be increased, the ECU 28 indicates “open the first valve portion and the second valve portion of the on-off valve 24”. A control signal is transmitted to the actuator 25.

  With reference to FIGS. 1-3, the operation | movement for suppressing the self-excited vibration in the bearing apparatus 20 is demonstrated.

  At the start of vehicle travel, the first and second valve portions of the on-off valve 24 are closed. Accordingly, the connection oil passage 21 and the compressor side bearing adjustment oil passage 22 are cut off, and the connection oil passage 21 and the turbine side bearing adjustment oil passage 23 are cut off, so that the compressor side fully floating bearing 8 and the spacer 10 are separated. Oil is not ejected between the turbine and the turbine side fully floating bearing 9 and the spacer 10.

  During the traveling of the vehicle, the oil sent to the main oil passage 11 is supplied to the storage portion 4a through the supply oil passages 12 and 13. The supplied oil is filled in a gap between the outer peripheral surfaces of the two fully floating bearings 8 and 9 and the inner surface of the storage portion 4a, and the inner peripheral surfaces of the two fully floating bearings 8 and 9 and the shaft 5 Filled with gaps. As a result, an oil film is formed in the gap on the outer peripheral side and the gap on the inner peripheral side of the two fully floating bearings 8 and 9, respectively, and the shaft 5 rotates while floating on the two fully floating bearings 8 and 9, The two fully floating bearings 8 and 9 rotate while being dragged by the shaft 5 through the oil film.

  The engine speed sensor 26 detects the engine speed and transmits the detected value to the ECU 28. The engine load sensor 27 detects the engine load and transmits the detected value to the ECU 28.

  The ECU 28 receives detection signals from the sensors 26 and 27. Then, the ECU 28 determines whether or not the relationship between the current engine speed and the engine load is within a region where self-excited vibration is likely to occur based on the engine speed-engine load map at regular intervals. . When it is determined that it is not in a region where self-excited vibration is likely to occur, the ECU 28 does not transmit a control signal to the actuator 25 when the two valve portions of the on-off valve 24 are closed, and at least the on-off valve 24 When one valve portion is in an open state, a control signal indicating “the valve portion is closed” is transmitted to the actuator 25. When this control signal is received, the actuator 25 closes the valve portion. Therefore, in the on-off valve 24, the first valve portion and the second valve portion are closed, and no oil is ejected between the all floating bearings 8 and 9 and the spacer 10, as described above.

  If it is determined that the vehicle is in a region where self-excited vibration is likely to occur, the ECU 28 determines the values of the all-floating bearings 8 and 9 for each value of the current engine speed and engine load based on the bearing speed control map. It is determined which bearing rotation number is to be increased.

  When it is determined that the rotation speed of the compressor-side fully floating bearing 8 has increased, the ECU 28 transmits a control signal indicating “open the first valve portion of the on-off valve 24” to the actuator 25. When this control signal is received, the actuator 25 opens the first valve portion. Then, the connection oil passage 21 and the compressor side bearing adjustment oil passage 22 are in communication with each other, and the oil sent to the main oil passage 11 passes through the connection oil passage 21, the on-off valve 24, and the compressor side bearing adjustment oil passage 22. Then, it is ejected between the compressor side fully floating bearing 8 and the spacer 10. The jetted oil presses the compressor side fully floating bearing 8 toward the compressor side and presses it against the thrust collar 14. Therefore, the compressor-side fully floating bearing 8 is dragged by the rotation of the thrust collar 14 that is rotating together with the shaft 5 to accelerate the rotation, and the rotation speed increases. At this time, the rotational speed of the compressor-side fully floating bearing 8 is relatively higher than the rotational speed of the turbine-side fully floating bearing 9. By increasing the rotation speed of the compressor side fully floating bearing 8, the oil film rigidity on the compressor side is stabilized and self-excited vibration is suppressed.

  When it is determined that the rotational speed of the turbine-side fully floating bearing 9 is increased, the ECU 28 transmits a control signal indicating “open the second valve portion of the on-off valve 24” to the actuator 25. When this control signal is received, the actuator 25 opens the second valve unit. Then, the connection oil passage 21 and the turbine side bearing adjustment oil passage 23 are in communication with each other, and the oil sent to the main oil passage 11 passes through the connection oil passage 21, the on-off valve 24, and the turbine side bearing adjustment oil passage 23. Then, it is ejected between the turbine side fully floating bearing 9 and the spacer 10. The jetted oil presses the turbine-side fully floating bearing 9 toward the turbine and presses it against the bearing end surface 7 a of the turbine 7. For this reason, the turbine-side fully floating bearing 9 is dragged by the rotation of the bearing end surface 7a rotating together with the shaft 5 to accelerate the rotation, and the rotation speed increases. At this time, the rotational speed of the turbine-side fully floating bearing 9 is relatively higher than the rotational speed of the compressor-side fully floating bearing 8. By increasing the rotational speed of the turbine-side fully floating bearing 9, the turbine-side oil film rigidity is stabilized and self-excited vibration is suppressed.

  When it is determined that the rotational speeds of both the fully floating bearings 8 and 9 are increased, the ECU 28 transmits a control signal indicating “open the first valve portion and the second valve portion of the on-off valve 24” to the actuator 25. When this control signal is received, the actuator 25 opens the first valve portion and the second valve portion. Then, the connection oil passage 21 and the compressor side bearing adjustment oil passage 22 and the connection oil passage 21 and the turbine side bearing adjustment oil passage 23 are in communication with each other, and the oil sent to the main oil passage 11 is in the compressor side fully floating bearing. 8 and between the spacer 10 and the turbine side fully floating bearing 9 and the spacer 10. The jetted oil presses the compressor-side fully floating bearing 8 against the thrust collar 14 and the turbine-side fully floating bearing 9 against the bearing end surface 7 a of the turbine 7. Therefore, the rotational speed of the compressor-side fully floating bearing 8 increases and the rotational speed of the turbine-side fully floating bearing 9 increases. At this time, the rotational speed of the compressor-side fully floating bearing 8 and the rotational speed of the turbine-side fully floating bearing 9 become higher than usual. By increasing the rotational speeds of both the all floating bearings 8 and 9, the oil film rigidity on the compressor side and the turbine side is stabilized, and self-excited vibration is suppressed.

  According to the bearing device 20, by controlling the rotational speed of the all-floating bearings 8 and 9, the self-excited vibration of the shaft 5 can be suppressed dynamically according to the operating state of the engine. In the bearing device 20, the rotational speed of the fully floating bearings 8 and 9 can be controlled by a simple configuration in which oil is jetted toward the fully floating bearings 8 and 9. Further, in the bearing device 20, since the two all-floating bearings 8 and 9 can be used with the same bearing specifications, the parts can be made common and there is no problem of erroneous assembly during manufacture.

  With reference to FIG. 4, the bearing apparatus 30 which concerns on 2nd Embodiment is demonstrated. FIG. 4 is a front sectional view of a bearing device for a turbocharger according to the second embodiment. In the bearing device 30, the same reference numerals are given to the same components as those of the bearing device 20 according to the first embodiment, and the description thereof is omitted.

  Compared with the bearing device 20, the bearing device 30 has a mechanism for suppressing the self-excited vibration in addition to controlling the rotational speed of the fully floating bearings 8 and 9 in order to suppress the self-excited vibration. ing. In the bearing device 30, in order to reduce the rotational speed of one of the two fully floating bearings 8 and 9, a braking force is applied to the one bearing. Therefore, the bearing device 30 is different in the configuration of the bearing device 20 and the spacer 31.

  Depending on the turbocharger 1 and the specifications and operating conditions of the engine, the rotational speeds of the two fully floating bearings 8 and 9 are not necessarily the same. Therefore, the oil film rigidity between the compressor side and the turbine side becomes unbalanced, and self-excited vibration may occur. When it is known in advance from the turbocharger 1 and engine specifications that self-excited vibration may occur due to such factors, the rotational speeds of the two fully floating bearings 8 and 9 are the same. Such a mechanism can be incorporated in advance. Therefore, the bearing device 30 is characterized by the shape of the spacer 31 as a mechanism for reducing the rotational speed of the bearing, which is predicted to increase in order to eliminate the unbalanced rotational speed.

  The spacer 31 has a cylindrical shape, and a plurality of oil holes 31a penetrating the inner surface side and the outer surface side are provided at the center thereof. Of the both end surfaces of the spacer 31 that are in contact with the all-floating bearings 8 and 9, the end surface on the bearing side where the rotational speed is to be reduced is formed flat across the entire width, and the other end surface on the other bearing side is tapered on the inner surface side and outer surface side, respectively. Portions 31b and 31c are formed. Therefore, the end surface on the bearing side where the rotation speed of the spacer 31 is desired to be reduced has a rectangular cross-sectional shape, and the other end surface of the spacer 31 has an isosceles trapezoidal cross-sectional shape. In the case of the example shown in FIG. 4, tapered portions 31 b and 31 c are formed on the end surface of the spacer 31 on the compressor side in order to reduce the rotational speed of the turbine-side fully floating bearing 9.

  With reference to FIG. 4, the effect | action of the spacer 31 in the bearing apparatus 30 is demonstrated. Here, the case where the taper parts 31b and 31c are provided in the end surface by the side of the compressor of the spacer 31 shown in FIG. 4 is demonstrated. In this case, if the action of the spacer 31 does not work, the rotational speed of the turbine-side fully floating bearing 9 becomes higher than the rotational speed of the compressor-side fully floating bearing 8.

  When the oil from the main oil passage 11 is supplied to the outer peripheral surface side of the compressor-side fully floating bearing 8 through the supply oil passage 12, it flows to the inner peripheral surface side through the oil hole 8a and In the clearance on the outer peripheral surface side of the floating bearing 8, the air flows toward the turbine side and the compressor side. The oil that has flowed to the inner peripheral surface side also flows toward the turbine side and the compressor side in the gap on the inner peripheral surface side of the compressor-side fully floating bearing 8. The oil flowing toward the compressor side hits the inclined surface of the tapered portion 31c on the outer peripheral surface side, and hits the inclined surface of the tapered portion 31b on the inner peripheral surface side.

  The spacer 31 is pressed to the turbine side by the fluid pressure of the oil received by the taper portions 31 b and 31 c and pressed against the turbine-side fully floating bearing 9. As a result, the frictional force between the spacer 31 and the turbine-side fully floating bearing 9 increases, and the non-rotating spacer 31 acts as a braking force for the turbine-side fully floating bearing 9. As a result, the rotation of the turbine-side fully floating bearing 9 is suppressed and the rotational speed is reduced. Due to the decrease in the rotational speed of the turbine-side fully floating bearing 9, the rotational speed of the compressor-side fully floating bearing 8 and the rotational speed of the turbine-side fully floating bearing 9 become the same rotational speeds. The oil film rigidity is balanced and self-excited vibration is suppressed.

  According to the bearing device 30, the effect of the bearing device 20 according to the first embodiment is obtained, and the balance between the rotational speeds of the two all-floating bearings 8 and 9 is achieved, whereby the specifications of the turbocharger 1 are achieved. The self-excited vibration that can be predicted in advance can be suppressed. In this bearing device 30, the rotation speed of one bearing can be forcibly reduced to balance the rotation speed by a simple configuration in which the tapered portions 31 b and 31 c are provided on the spacer 31.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  For example, in the present embodiment, the present invention is applied to a turbocharger that is mounted on an automobile and includes a compressor-side fully floating bearing and a turbine-side fully floating bearing that have the same bearing specifications, but can also be applied to a turbocharger other than an automobile. In addition, the present invention can also be applied to a turbocharger including a compressor-side fully floating bearing and a turbine-side fully floating bearing with different bearing specifications.

  In the present embodiment, the rotational speed of each bearing is controlled by jetting oil between each bearing and the spacer. However, the rotational speed of each bearing may be controlled by other methods. . For example, the divided spacers divided into two can be moved in the respective bearing directions, the divided spacers are moved in the direction of the bearings by the actuators, and the bearings are pressed by the divided spacers to control the rotation speed of each bearing. .

  In this embodiment, one on-off valve is provided to open and close the compressor-side bearing adjustment oil passage and the turbine-side bearing adjustment oil passage. However, the compressor-side bearing adjustment oil passage and the turbine-side bearing adjustment oil passage are opened and closed respectively. It is good also as a structure which provides a valve.

  In the present embodiment, the compressor-side bearing adjustment oil passage and the turbine-side bearing adjustment oil passage are opened / closed by the on-off valve to increase the rotational speeds of the compressor-side fully floating bearing and the turbine-side fully floating bearing. However, each opening of the compressor-side bearing adjustment oil passage and the turbine-side bearing adjustment oil passage is adjusted in stages, and the rotational speeds of the compressor-side fully floating bearing and turbine-side fully floating bearing are adjusted. It may be configured to control in stages, or normally, each bearing adjustment oil passage is opened, and whether or not the rotation speeds of the compressor side fully floating type bearing and the turbine side fully floating type bearing are reduced during control is determined. It is good.

  In the present embodiment, the rotational speed of each bearing is controlled based on the engine speed and the engine load. However, the control may be performed based on other engine operating conditions such as engine torque, Control may be performed based on the operating conditions of the turbocharger such as the compressor speed, the turbine speed, the supercharging pressure, or the control may be performed based on the operating conditions of the engine and the operating conditions of the turbocharger. .

  In the second embodiment, the turbocharger capable of controlling the rotation speed of each bearing is provided with a spacer having a tapered portion. However, when this spacer is provided in a turbocharger where the rotation speed of each bearing cannot be controlled. However, there is an effect of suppressing self-excited vibration by reducing the rotational speed of one of the bearings. In this case, a stopper that prevents movement of the bearing to the compressor side between the compressor-side fully floating bearing and the thrust collar, or a turbine-side bearing between the turbine-side fully floating bearing and the bearing end surface of the turbine, If the stopper which prevents the movement of this is provided, the brake force by a spacer will act more effectively.

1 is a front sectional view of a turbocharger according to the present embodiment. It is a front sectional view of a bearing device of a turbocharger concerning a 1st embodiment. It is a block diagram of the control system of the bearing device of the turbocharger which concerns on this Embodiment. It is a front sectional view of a bearing device for a turbocharger according to a second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Turbocharger, 2 ... Compressor housing, 3 ... Turbine housing, 4 ... Bearing housing, 4a ... Storage part, 5 ... Shaft, 6 ... Compressor, 6a ... Nut, 7 ... Turbine, 7a ... Bearing end surface, 8 ... Compressor side Fully floating bearing, 8a ... oil hole, 9 ... Turbine side fully floating bearing, 9a ... oil hole, 10 ... spacer, 10a ... oil hole, 11 ... main oil passage, 12, 13 ... supply oil passage, 14 ... thrust Collar, 15 ... Thrust bearing, 20 ... Bearing device, 21 ... Connection oil passage, 22 ... Compressor side bearing adjustment oil passage, 23 ... Turbine side bearing adjustment oil passage, 24 ... Open / close valve, 25 ... Actuator, 26 ... Engine speed Sensor 27 ... Engine load sensor 28 ... ECU 30 Bearing device 31 Spacer 31a Oil hole 31b 31c Taper

Claims (2)

In a turbocharger bearing device provided with a compressor side bearing and a turbine side bearing as a bearing of a rotating shaft connecting the compressor and the turbine,
Bearing rotational speed control means for controlling the rotational speeds of the compressor side bearing and the turbine side bearing,
A bearing device for a turbocharger, wherein the bearing rotational speed control means controls each rotational speed based on an operating condition of the engine or / and an operating condition of the turbocharger. The bearing rotation speed control means includes
A compressor-side oil passage for supplying oil that presses the compressor-side bearing toward the compressor;
A turbine-side oil passage that supplies oil that presses the turbine-side bearing toward the turbine;
A valve for adjusting each opening of the compressor side oil passage and the turbine side oil passage;
An actuator for opening and closing the valve;
The turbocharger bearing device according to claim 1, further comprising: a control unit that controls driving of the actuator based on engine operating conditions and / or turbocharger operating conditions.

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