JP2006125343A - Turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turbocharger capable of sufficiently supplying lubricating oil to a contact face with a shaft side in thrust direction of a thrust bearing while maintaining supply pressure of lubricating oil to be supplied to the thrust bearing at low pressure. <P>SOLUTION: In this turbocharger, a main oil supply passage 38 in which an oil supply port 38a faces an outer peripheral face of a shaft 17 (17a) and a first auxiliary oil supply passage 39 and a second auxiliary oil supply passage 40 being independent from the main oil supply passage 38 are formed in the thrust bearing 26. An oil supply port 39a of the first auxiliary oil supply passage 39 is opened at a position being eccentric on a turbine wheel side of the thrust bearing 26, and an oil supply port 40a of the second auxiliary oil supply passage 40 is opened at a position being eccentric on a compressor wheel side. The first and second auxiliary oil supply passages 39, 40 are opened or closed in accordance with travel of the shaft 17 (17a) in thrust direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a turbocharger including a thrust bearing that restricts movement in a thrust direction of a shaft connecting two wheels for a turbine and a compressor.

As is well known, a turbocharger includes a turbine provided in an exhaust system of an internal combustion engine and a compressor provided in an intake system of the engine. As an example of such a turbocharger, Technical Document 1 is cited. In the turbocharger of the technical document 1, as shown in FIG. 8A, the wheels provided in the turbine and the compressor, that is, the turbine wheel (not shown) and the compressor wheel 91 are connected to one shaft 92 so as to be integrally rotatable. Has been. The shaft 92 is rotatably supported in the housing 93 via a thrust bearing 94 while its movement in the thrust direction is restricted. According to such a mechanism, when the turbine wheel is rotationally driven by the exhaust of the internal combustion engine, the rotation is transmitted to the compressor wheel 91 through the shaft 92. When the compressor wheel 91 is rotated, the intake fresh air (air) is compressed, and the compressed intake air is forcibly pumped to the combustion chamber of the engine. Since the shaft 92 rotates at a high speed, oil supply passages 95 and 96 are interposed between the outer peripheral surface of the shaft 92 and the thrust bearing 94 as shown in FIGS. 8B and 8C. Oil (lubricating oil) is supplied.
Japanese Patent No. 3268361

  When the lubricating oil is supplied between the outer peripheral surface of the shaft 92 and the thrust bearing 94, the lubricating oil is forcibly supplied at a predetermined pressure (however, specific supply means is disclosed in Patent Document 1). There is no disclosure). However, in this type of turbocharger, if the supply pressure of the lubricating oil is too high, the friction loss on the sliding surface tends to increase, which is not preferable. Specifically, an increase in the supply pressure of the lubricating oil, for example, causes an increase in energy for driving an auxiliary machine that generates the supply pressure. Deterioration of fuel efficiency will occur. For this reason, the supply pressure of the lubricating oil is set to be low so as not to affect these points so much, and a decrease in bearing capacity accompanying a decrease in the supply pressure of the lubricating oil increases the pressure receiving area (that is, increases the sliding area). )). This is a factor that causes the efficiency of the turbocharger to deteriorate.

  By the way, the lubricating oil supplied between the outer peripheral surface of the shaft 92 and the thrust bearing 94 is a contact surface in the thrust direction between the thrust bearing 94 and the shaft 92 (in Patent Document 1, the bushing 97 and the operating side surfaces 98 and 99 The contact surface in the thrust direction is also ensured. However, when the supply pressure of the lubricating oil is low, there may be a case where the lubricant does not sufficiently reach the contact surface in the thrust direction. Therefore, the lubrication of the contact surface in the thrust direction is not sufficient, and the turbo efficiency is deteriorated in combination with the increase in the pressure receiving area.

  The present invention has been made paying attention to such problems existing in the prior art. The objective is to provide a turbocharger that sufficiently supplies lubricating oil to the contact surface with the shaft side in the thrust direction of the thrust bearing while maintaining the supply pressure of the lubricating oil supplied to the thrust bearing at a low pressure. It is to provide.

In the following, means for achieving the above object and its effects are described.
In the first aspect of the invention, the turbine wheel and the compressor wheel are coupled to the shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing, thereby restricting the movement of the shaft in the thrust direction. In the turbocharger, in which the rotation in the circumferential direction is allowed, the compressor wheel is driven to rotate by the rotation of the turbine wheel rotated by exhaust gas, and fresh air compressed by the compressor wheel is supplied to the engine. A main oil supply passage for supplying oil to the outer peripheral surface of the shaft is formed in the bearing, and an oil supply port of the main oil supply passage is biased to either the turbine wheel side or the compressor wheel side of the thrust bearing. Opened to the position The door and the gist thereof.

  If comprised in this way, when a turbine wheel is rotationally driven by engine exhaust_gas | exhaustion, the rotation will be transmitted to a compressor wheel via a shaft. By rotating the compressor wheel, the sucked fresh air (air) is compressed, and the compressed air is forcibly pumped to the combustion chamber of the engine. Despite the high-speed rotation of the shaft, the supply pressure of the lubricating oil supplied to the sliding portion of the shaft supported by the thrust bearing cannot be so high considering friction loss.

  Therefore, the oil supply port of the main oil supply passage for supplying oil to the outer peripheral surface of the shaft is opened at a position biased to either the turbine wheel side or the compressor wheel side of the thrust bearing. As a result, the lubricating oil is supplied to the outer peripheral surface, and at the same time, a large amount of lubricating oil is supplied to either the turbine wheel side or the compressor wheel side. In other words, the lubricating oil can be preferentially supplied to this portion by biasing the oil supply port of the main oil supply passage toward the side where the contact pressure between the thrust bearing and the shaft is higher in the thrust direction.

  In the invention according to claim 2, the turbine wheel and the compressor wheel are coupled to the shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing, thereby restricting movement of the shaft in the thrust direction. In a turbocharger that allows rotation of the shaft in the circumferential direction, rotates the compressor wheel following rotation of the turbine wheel rotated by exhaust, and supplies fresh air compressed by the compressor wheel to the engine. In the thrust bearing, a fuel supply port forms a main oil supply passage facing the outer peripheral surface of the shaft, a branch oil supply passage branched from the main oil supply passage is formed, and the oil supply port of the branch oil supply passage is connected to the thrust bearing. The turbine wheel side and the compressor wheel That it has to be opened in a position offset to either side of the side as its gist.

  If comprised in this way, when a turbine wheel is rotationally driven by engine exhaust_gas | exhaustion, the rotation will be transmitted to a compressor wheel via a shaft. As the compressor wheel rotates, the sucked fresh air (air) is compressed, and the compressed air is forcibly pumped to the combustion chamber of the engine. Despite the high-speed rotation of the shaft, the supply pressure of the lubricating oil supplied to the sliding portion of the shaft supported by the thrust bearing cannot be so high considering friction loss.

  Therefore, a branch oil supply passage is formed in the main oil supply passage for supplying oil to the outer peripheral surface of the shaft, and the oil supply port of the branch oil supply passage is biased to either the turbine wheel side or the compressor wheel side of the thrust bearing. Open at the specified position. As a result, the lubricating oil is supplied to the outer peripheral surface, and at the same time, the lubricating oil is supplied to either the turbine wheel side or the compressor wheel side through the branch oil supply passage. In other words, the lubricating oil can be preferentially supplied to this portion by biasing the oil supply port of the branch oil supply passage toward the side where the contact pressure between the thrust bearing and the shaft is higher in the thrust direction.

  Further, in the invention according to claim 3, in addition to the configuration of the invention according to claim 2, the oil supply port of the branch oil supply passage is one of the side surface on the turbine wheel side and the side surface on the compressor wheel side of the thrust bearing. The gist of this is to open it facing the surface. That is, the side surface on the turbine wheel side and the side surface on the compressor wheel side of the thrust bearing are contact surfaces in the thrust direction with the thrust movement restricting surface of the shaft (for example, the side surface of the bushing). Lubricating oil can be quickly supplied to the contact surface between the thrust bearing and the shaft in the thrust direction.

  In the invention according to claim 4, the turbine wheel and the compressor wheel are connected to the shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing, thereby restricting movement of the shaft in the thrust direction. In a turbocharger that allows rotation of the shaft in the circumferential direction, rotates the compressor wheel following rotation of the turbine wheel rotated by exhaust, and supplies fresh air compressed by the compressor wheel to the engine. The thrust bearing forms a main oil supply passage with an oil supply port facing the outer peripheral surface of the shaft, and also forms first and second branch oil supply passages branched from the main oil supply passage. The oil supply port of the branch oil supply passage is biased toward the turbine wheel side of the thrust bearing. It is opened to a position, as its gist in that the fuel supply port of the second branch oil supply passages so as to open in a position offset to the compressor wheel side.

  If comprised in this way, when a turbine wheel is rotationally driven by engine exhaust_gas | exhaustion, the rotation will be transmitted to a compressor wheel via a shaft. As the compressor wheel rotates, the sucked fresh air (air) is compressed, and the compressed air is forcibly pumped to the combustion chamber of the engine. Despite the high-speed rotation of the shaft, the supply pressure of the lubricating oil supplied to the sliding portion of the shaft supported by the thrust bearing cannot be so high considering friction loss.

  Therefore, the first and second branch oil supply passages are formed in the main oil supply passage for supplying oil to the outer peripheral surface of the shaft, and the oil supply port of the first branch oil supply passage is opened at a position biased toward the turbine wheel side of the thrust bearing. The oil supply port of the second branch oil supply passage is opened at a position biased toward the turbine wheel. As a result, the lubricating oil is supplied to the outer peripheral surface, and at the same time, the lubricating oil is supplied also to the turbine wheel side and the compressor wheel side of the thrust bearing through the first and second branch oil supply passages, respectively. Accordingly, the lubricating oil can be sufficiently supplied around the contact surface between the thrust bearing and the shaft side in the thrust direction.

  Further, in the invention according to claim 5, in addition to the configuration of the invention according to claim 4, the oil supply port of the first branch oil supply passage faces the side surface of the thrust bearing on the turbine wheel side, and The gist is that the oil supply port of the second branch oil supply passage is opened to the side surface on the compressor wheel side.

  That is, the side surface on the turbine wheel side and the side surface on the compressor wheel side of the thrust bearing are contact surfaces in the thrust direction with the thrust movement restricting surface of the shaft (for example, the side surface of the bushing). Lubricating oil can be quickly supplied to the contact surface between the thrust bearing and the shaft in the thrust direction.

  In the invention described in claim 6, the turbine wheel and the compressor wheel are connected to the shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing, thereby restricting movement of the shaft in the thrust direction. In a turbocharger that allows rotation of the shaft in the circumferential direction, rotates the compressor wheel following rotation of the turbine wheel rotated by exhaust, and supplies fresh air compressed by the compressor wheel to the engine. In the thrust bearing, a main oil supply passage having an oil supply port facing the outer peripheral surface of the shaft and a sub oil supply passage independent of the main oil supply passage are formed, and the oil supply port of the sub oil supply passage is connected to the oil supply port of the thrust bearing. Either the turbine wheel side or the compressor wheel side That it has to be opened in the biased position as its gist.

  If comprised in this way, when a turbine wheel is rotationally driven by engine exhaust_gas | exhaustion, the rotation will be transmitted to a compressor wheel via a shaft. As the compressor wheel rotates, the sucked fresh air (air) is compressed, and the compressed air is forcibly pumped to the combustion chamber of the engine. Despite the high-speed rotation of the shaft, the supply pressure of the lubricating oil supplied to the sliding portion of the shaft supported by the thrust bearing cannot be so high considering friction loss.

  Therefore, in order to supply oil to the outer peripheral surface of the shaft, a sub oil supply passage independent of the main oil supply passage is formed, and the oil supply port of the sub oil supply passage is set to one of the turbine wheel side and the compressor wheel side of the thrust bearing. Open at a position biased to the side. As a result, the lubricating oil is supplied to the outer peripheral surface, and at the same time, the lubricating oil is supplied to either the turbine wheel side or the compressor wheel side through the auxiliary oil supply passage. In other words, the lubricating oil can be preferentially supplied to this portion by biasing the oil supply port of the auxiliary oil supply passage toward the side where the contact pressure between the thrust bearing and the shaft is higher in the thrust direction.

  Further, in the invention according to claim 7, in addition to the configuration of the invention according to claim 6, the oil supply port of the auxiliary oil supply passage is one of the side surface on the turbine wheel side and the side surface on the compressor wheel side of the thrust bearing. The gist of this is to open it facing the surface. That is, the side surface on the turbine wheel side and the side surface on the compressor wheel side of the thrust bearing are contact surfaces in the thrust direction with the thrust movement restricting surface of the shaft (for example, the side surface of the bushing). Lubricating oil can be quickly supplied to the contact surface between the thrust bearing and the shaft in the thrust direction.

  Further, in the invention according to claim 8, in addition to the configuration of the invention according to claim 6 or 7, on the basis of a change in operating condition parameter which causes a change in the position of the shaft in the thrust direction with respect to the thrust bearing. The gist is that the flow rate of the lubricating oil supplied to the auxiliary oil supply passage is variable.

  First, in the turbocharger, the position of the shaft changes in the thrust direction with respect to the thrust bearing in accordance with operating conditions. In other words, the force that moves the shaft toward the compressor wheel increases as the pressure of the fresh air supercharged by the compressor wheel (supercharging pressure) increases relative to the back pressure of the turbine wheel. The power to move increases. Since the supercharging pressure and the back pressure change according to operating conditions, for example, parameters such as the engine speed, the shaft moves in the thrust direction so that it can be reversed. When the shaft moves to the turbine wheel side, the thrust movement restricting surface (for example, the side surface of the bushing) of the shaft comes into contact with one side surface of the thrust bearing in the thrust direction, and when the shaft moves to the compressor wheel side, it comes into contact with the other side surface. When the thrust movement restricting surface of the shaft and the side surface of the thrust bearing are not in contact, it is preferable that no oil pressure is applied between both surfaces because friction resistance due to the oil pressure is eliminated.

  Therefore, it is preferable that the flow rate of the lubricating oil supplied to the auxiliary oil supply passage is made variable in accordance with the change in the operating condition parameter, as in the invention of claim 8. More specifically, for example, when there are many opportunities for the shaft to move to the compressor wheel side, the oil supply port of the auxiliary oil supply passage is opened to a position biased to the turbine wheel side. Then, the control is performed so that the flow rate of the lubricating oil supplied to the auxiliary oil supply passage side is increased even if the shaft is moved to the compressor wheel side. On the other hand, when the shaft is moved to the turbine wheel side, control is performed so that the flow rate of the lubricating oil supplied to the auxiliary oil supply passage is reduced (or the supply of the lubricating oil is stopped). This improves the lubrication efficiency of the portion where the thrust movement restricting surface of the shaft contacts the side surface of the thrust bearing, and eliminates the frictional resistance due to hydraulic pressure in the gap between the thrust bearing and the shaft for the non-contact portion. . The variable here is a concept including a case where no pressure is applied. The operating condition parameters include engine speed, fuel injection amount, supercharging pressure, opening of a variable nozzle vane for adjusting the pressure of exhaust gas supplied to the turbine, and the like.

  In the ninth aspect of the invention, the turbine wheel and the compressor wheel are connected to a shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing to restrict movement of the shaft in the thrust direction. In a turbocharger that allows rotation of the shaft in the circumferential direction, rotates the compressor wheel following rotation of the turbine wheel rotated by exhaust, and supplies fresh air compressed by the compressor wheel to the engine. In the thrust bearing, there are formed a main oil supply passage having an oil supply port facing the outer peripheral surface of the shaft, and first and second sub oil supply passages independent of the main oil supply passage. Open the oil filler port at a position biased to the turbine wheel side of the thrust bearing. A refueling port of the auxiliary oil supply passage that so as to open in a position offset to the compressor wheel side to the invention.

  If comprised in this way, when a turbine wheel is rotationally driven by engine exhaust_gas | exhaustion, the rotation will be transmitted to a compressor wheel via a shaft. As the compressor wheel rotates, the sucked fresh air (air) is compressed, and the compressed air is forcibly pumped to the combustion chamber of the engine. Despite the high-speed rotation of the shaft, the supply pressure of the lubricating oil supplied to the sliding portion of the shaft supported by the thrust bearing cannot be so high considering friction loss.

  Therefore, in order to supply oil to the outer peripheral surface of the shaft, first and second auxiliary oil supply passages independent of the main oil supply passage are formed, and the oil supply ports of these auxiliary oil supply passages are connected to the turbine wheel side of the thrust bearing and the compressor. Open each at a position biased to the wheel side. As a result, the lubricating oil is supplied to the outer peripheral surface, and at the same time, the lubricating oil is supplied to both sides of the turbine wheel side and the compressor wheel side through the auxiliary oil supply passages. Accordingly, the lubricating oil can be sufficiently supplied around the contact surface between the thrust bearing and the shaft in the thrust direction.

  Further, in the invention according to claim 10, in addition to the structure of the invention according to claim 9, the oil supply port of the first sub oil supply passage faces the side surface of the thrust bearing on the turbine wheel side, and The gist is that the oil supply port of the second auxiliary oil supply passage is opened on the side surface on the compressor wheel side.

  That is, the side surface on the turbine wheel side and the side surface on the compressor wheel side of the thrust bearing are contact surfaces in the thrust direction with the thrust movement restricting surface of the shaft (for example, the side surface of the bushing). Lubricating oil can be quickly supplied to the contact surface between the thrust bearing and the shaft in the thrust direction.

  Further, in the invention according to claim 11, in addition to the configuration of the invention according to claim 9 or 10, based on the change of the parameter of the operating condition which causes the change of the position of the shaft in the thrust direction with respect to the thrust bearing. The gist is that the flow rate of the lubricating oil supplied to the first and second auxiliary oil supply passages is variable.

  First, in the turbocharger, the position of the shaft changes in the thrust direction with respect to the thrust bearing in accordance with operating conditions. In other words, the force that moves the shaft toward the compressor wheel increases as the pressure of the fresh air supercharged by the compressor wheel (supercharging pressure) increases relative to the back pressure of the turbine wheel. The power to move increases. Since the supercharging pressure and the back pressure change according to operating conditions, for example, parameters such as the engine speed, the shaft moves in the thrust direction so as to be able to move forward and backward. When the shaft moves to the turbine wheel side, the thrust movement restricting surface (for example, the side surface of the bushing) of the shaft contacts one side surface of the thrust bearing in the thrust direction, and when the shaft moves to the compressor wheel side, the other side surface contacts. When the thrust movement restricting surface of the shaft and the side surface of the thrust bearing are not in contact, it is preferable that no oil pressure is applied between these surfaces because friction resistance due to the oil pressure is eliminated.

  Therefore, it is preferable that the flow rate of the lubricating oil supplied to the first and second auxiliary oil supply passages is made variable in accordance with changes in the parameters of the operating conditions as in the invention of claim 11. The operating condition parameters include engine speed, fuel injection amount, supercharging pressure, opening of a variable nozzle vane for adjusting the pressure of exhaust gas supplied to the turbine, and the like. More specifically, for example, the control is performed so that the flow rate of the lubricating oil supplied to the second auxiliary oil supply passage is increased even if the shaft is moved to the turbine wheel side. On the other hand, when the shaft is moved to the compressor wheel side, control is performed so that the flow rate of the lubricating oil supplied to the first sub oil supply passage is increased. This improves the lubrication efficiency of the portion where the thrust movement regulating surface of the shaft contacts the side surface of the thrust bearing, and eliminates the frictional resistance due to the hydraulic pressure in the gap between the thrust bearing and the shaft for the non-contact portion.

  In addition, when increasing the flow rate of the lubricating oil supplied to one sub-lubricating passage, the flow rate of the lubricating oil supplied to the other sub-lubricating passage is reduced compared to the one sub-lubricating passage, or the lubricating oil It is preferable to control such as stopping the supply. For example, the flow rate of the lubricating oil supplied to one of the sub oil supply passages is 70% of the total (total flow rate in the first and second sub oil supply passages), and the other sub oil supply passage is the remaining, that is, 30%, or There is a control mode in which one sub oil supply passage is set to 100% and the other sub oil supply passage is set to 0%. That is, the variable is a concept including a case where no pressure is applied.

  Further, as a configuration in which the flow rate of the lubricating oil is variable, as in the invention according to a twelfth aspect, in the invention according to the eleventh aspect, the lubricating oil is connected to the first and second auxiliary oil supply passages and lubricated. A mode in which a control valve for distributing lubricating oil supplied from an oil supply source to the first and second auxiliary oil supply passages can be employed. According to this, for example, the number of valves can be reduced as compared with the case where the valves for flow rate adjustment are individually provided in both the auxiliary oil supply passages.

  In the invention according to claim 13, the turbine wheel and the compressor wheel are coupled to the shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing, thereby restricting movement of the shaft in the thrust direction. In a turbocharger that allows rotation of the shaft in the circumferential direction, rotates the compressor wheel following rotation of the turbine wheel rotated by exhaust, and supplies fresh air compressed by the compressor wheel to the engine. The thrust bearing forms first and second main oil supply passages whose oil supply ports face the outer peripheral surface of the shaft, and the oil supply ports of the first main oil supply passages are arranged on the turbine wheel side of the thrust bearing. And open the oil supply port of the second main oil supply passage. That it has to be open to the serial and biased to the compressor wheel side position as its gist.

  If comprised in this way, when a turbine wheel is rotationally driven by engine exhaust_gas | exhaustion, the rotation will be transmitted to a compressor wheel via a shaft. As the compressor wheel rotates, the sucked fresh air (air) is compressed, and the compressed air is forcibly pumped to the combustion chamber of the engine. Despite the high-speed rotation of the shaft, the supply pressure of the lubricating oil supplied to the sliding portion of the shaft supported by the thrust bearing cannot be so high considering friction loss.

  Therefore, first and second main oil supply passages independent of the main oil supply passage are formed to supply oil to the outer peripheral surface of the shaft, and the oil supply ports of these sub oil supply passages are connected to the turbine wheel side of the thrust bearing and the compressor. Open each at a position biased toward the wheel. As a result, the lubricating oil is supplied to the outer peripheral surface, and at the same time, the lubricating oil is supplied to both the turbine wheel side and the compressor wheel side through the auxiliary oil supply passages. Accordingly, the lubricating oil can be sufficiently supplied around the contact surface between the thrust bearing and the shaft in the thrust direction.

  In addition to the configuration of the invention described in claim 13, in the invention described in claim 14, a first branch oil supply passage is formed in the first main oil supply passage, and the second main oil supply passage is formed. Has a second branch oil supply passage, the oil supply port of the first branch oil supply passage faces the side surface of the thrust bearing on the turbine wheel side, and the oil supply port of the second branch oil supply passage is the The gist is to open the side of the compressor wheel.

  That is, the side surface on the turbine wheel side and the side surface on the compressor wheel side of the thrust bearing are contact surfaces in the thrust direction with the thrust movement restricting surface of the shaft (for example, the side surface of the bushing). Lubricating oil can be quickly supplied to the contact surface between the thrust bearing and the shaft in the thrust direction.

  Further, in the invention described in claim 15, in addition to the configuration of the invention described in claim 13 or 14, on the basis of a change in operating condition parameter which causes a change in position of the shaft in the thrust direction with respect to the thrust bearing. The gist is that the flow rate of the lubricating oil supplied to the first and second main oil supply passages is variable.

  First, in the turbocharger, the position of the shaft changes in the thrust direction with respect to the thrust bearing in accordance with operating conditions. In other words, the force to move the shaft toward the compressor wheel increases as the pressure of the fresh air supercharged by the compressor wheel (supercharging pressure) increases relative to the back pressure of the turbine wheel. The power to move increases. Since the supercharging pressure and the back pressure change according to operating conditions, for example, parameters such as the engine speed, the shaft moves in the thrust direction so as to be able to move forward and backward. When the shaft moves to the turbine wheel side, the thrust movement restricting surface (for example, the side surface of the bushing) of the shaft contacts one side surface of the thrust bearing in the thrust direction, and when the shaft moves to the compressor wheel side, the other side surface contacts. When the thrust movement restricting surface of the shaft and the side surface of the thrust bearing are not in contact, it is preferable that no oil pressure is applied between these surfaces because friction resistance due to the oil pressure is eliminated.

  Therefore, it is preferable that the flow rate of the lubricating oil supplied to the first and second main oil supply passages is made variable in accordance with changes in the parameters of the operating conditions as in the invention of the fifteenth aspect. The operating condition parameters include engine speed, fuel injection amount, supercharging pressure, opening of a variable nozzle vane for adjusting the pressure of exhaust gas supplied to the turbine, and the like. More specifically, for example, the control is performed so that the flow rate of the lubricating oil supplied to the second main oil supply passage is increased even if the condition that the shaft is moved toward the turbine wheel is satisfied. On the other hand, when the shaft is moved toward the compressor wheel, the flow rate of the lubricating oil supplied to the first main oil supply passage is controlled to be increased. This improves the lubrication efficiency of the portion where the thrust movement regulating surface of the shaft contacts the side surface of the thrust bearing, and eliminates the frictional resistance due to the hydraulic pressure in the gap between the thrust bearing and the shaft for the non-contact portion.

  When the flow rate of the lubricating oil supplied to one main oil supply passage is increased, the flow rate of the lubricating oil supplied to the other main oil supply passage is reduced compared to the one main oil supply passage, or the lubricating oil is supplied. It is preferable to control such as stopping the supply. For example, the flow rate of the lubricating oil supplied to one of the main oil supply passages is 70% of the total (total flow rates in the first and second main oil supply passages), and the other main oil supply passage is the remaining, that is, 30%, or There is a control mode in which one main oil supply passage is 100% and the other main oil supply passage is 0%. That is, the variable is a concept including a case where no pressure is applied.

  Further, as a configuration in which the flow rate of the lubricating oil is variable, as in the invention according to the sixteenth aspect, in the invention according to the fifteenth aspect, the lubricating oil is connected to the first and second main oil supply passages and lubricated. A mode of including a control valve for distributing lubricating oil supplied from an oil supply source to the first and second main oil supply passages can be employed. According to this, for example, the number of valves can be reduced as compared with the case where the flow rate adjusting valves are individually provided in both the main oil supply passages.

  In addition, in the invention according to claim 17, in addition to the configuration of the invention according to any one of claims 1 to 16, a flow path penetrating in the thrust direction formed between the thrust bearing and the outer peripheral surface of the shaft. In this regard, the gist of the present invention is that a portion having a large cross-sectional area and a portion having a small cross-sectional area are formed, and the oil filler opening is opened to the portion having a large cross-sectional area.

  With this configuration, the lubricating oil supplied to the flow path from the oil supply port becomes difficult to flow to the opposite side beyond this portion due to the passage resistance of the lubricating oil in the portion having a small cross-sectional area. Therefore, the lubricating oil supplied to the flow path from the oil supply port can be efficiently distributed to the lubrication location.

(Embodiment 1)
Hereinafter, a first embodiment in which the turbocharger of the present invention is embodied will be described with reference to the drawings. First, a schematic overall configuration of a turbocharger with variable nozzle vanes (hereinafter simply referred to as a turbocharger) 11 will be described with reference to FIG.

  As shown in FIG. 1, the turbocharger 11 includes a turbine housing 12 disposed in the exhaust passage of the engine, a compressor housing 13 disposed in the intake passage of the engine, and the turbine housing 12 and the compressor housing 13. And a bearing housing 14 for connecting the two.

  A turbine wheel 15 is disposed in the turbine housing 12 and is rotated by exhaust gas discharged from the combustion chamber of the engine. A compressor wheel 16 is disposed in the compressor housing 13. The compressor wheel 16 compresses fresh air flowing through the intake passage and pumps it to the combustion chamber. Both wheels 15 and 16 are coupled to each other by a rotor shaft 17 that is rotatably supported in the bearing housing 14.

  The turbine housing 12 is attached to one end of the bearing housing 14 so as to surround the outer periphery of the turbine wheel 15. In the turbine housing 12, there is provided a scroll passage 18 that circulates in a spiral shape. The scroll passage 18 communicates with the exhaust passage of the engine, and the exhaust from the combustion chamber is sent to the scroll passage 18 through the exhaust passage.

  An exhaust passage 19 that guides exhaust in the scroll passage 18 toward the turbine wheel 15 is provided in the turbine housing 12 along the extending direction of the scroll passage. A plurality of nozzle vanes 20 are arranged in the middle of the exhaust passage 19. The nozzle vane 20 is opened and closed by a variable nozzle mechanism 21 provided between the turbine housing 12 and the bearing housing 14, whereby the flow path cross-sectional area between the vanes 20 is variable. The variable nozzle mechanism 21 is driven by a first actuator 23 including a hydraulic motor and a hydraulic cylinder via a drive arm 21a.

  The compressor housing 13 is attached to the other end of the bearing housing 14 so as to surround the outer periphery of the compressor wheel 16. A compressor passage 25 that circulates in a spiral shape is provided in the compressor housing 13. The compressor passage 25 communicates with the combustion chamber. The compressor housing 13 is provided with a delivery passage 22 for sending fresh air (air) introduced into the housing 13 to the compressor passage 25.

  The rotor shaft 17 is rotatably supported by a roller bearing 24 and is restricted from moving in the thrust direction via a thrust bearing 26. The thrust bearing 26 is provided with a three-way switching valve (control valve) 27 for supplying lubricating oil, a tank 28 for storing lubricating oil, and a second actuator 29 including a hydraulic motor and a hydraulic cylinder. A tank 28 and a pump (lubricant supply source) P are connected to the switching valve 27.

  The first and second actuators 23 and 29 are controlled by an electronic engine management unit (ECU) 30. The ECU 30 controls the actuators 23 and 29 based on the output signal from the rotation speed sensor 31.

With regard to the turbocharger 11 of the first embodiment having such a basic configuration, the configuration around the thrust bearing 26 will be described in more detail.
As shown in FIG. 2, a cylindrical bearing metal 33 is fixed to the small diameter portion 17 a of the rotor shaft 17. The bearing metal 33 constitutes the outer peripheral surface of the rotor shaft 17 that is inserted into the through hole of the thrust bearing 26 and faces the inner peripheral surface of the hole. The thrust bearing 26 is disposed so as to be sandwiched between two bushings 34 and 35 disposed along the thrust direction of the rotor shaft 17. In the rotor shaft 17, a portion sandwiched between the bushings 34 and 35 (portion where the bearing metal 33 is provided) is referred to as an insertion portion 36. Both bushings 34 and 35 are installed slightly wider than the width of the thrust bearing 26 in order to allow the rotation of the rotor shaft 17 with respect to the thrust bearing 26. In FIG. (That is, the gap formed between the bushings 34, 35 and the end face of the thrust bearing 26 is larger than the actual one). In the first embodiment, the inner wall surface of the bushing 34 on the turbine wheel 15 side is a T surface, and the inner wall surface of the bushing 35 on the compressor wheel 16 side is a C surface.

  Between the through hole of the thrust bearing 26 and the outer peripheral surface of the bearing metal 33, a lubricating oil passage 37 penetrating in the thrust direction is formed. The lubricating oil passage 37 has a small-diameter passage 37a in which the vicinity of the center approaches the surface of the insertion portion 36 (outer peripheral surface of the bearing metal 33) and the interval is small, that is, the sectional area is small. The front and rear portions in the thrust direction adjacent to the small-diameter passage 37a are not approached like the small-diameter passage 37a, and are large-diameter passages 37b and 37c having a large distance from the surface of the insertion portion 36, that is, large cross-sectional areas.

  In the thrust bearing 26, oil supply passages 38, 39, 40 connected to the switching valve 27 are formed. An opening (oil supply port) 38 a of the main oil supply passage 38 is opened to the small diameter passage 37 a and faces the outer peripheral surface of the bearing metal 33. First and second auxiliary oil supply passages 39 and 40 are arranged in parallel with the main oil supply passage 38 in the front and rear of the thrust direction across the main oil supply passage 38. Openings (oil supply ports) 39a and 40a of the auxiliary oil supply passages 39 and 40 are opened to the large diameter passages 37b and 37c, respectively, and face the outer peripheral surface of the bearing metal 33.

The operation of the turbocharger 11 of the first embodiment configured as described above will be described.
First, the movement of the rotor shaft 17 in the thrust direction as the turbocharger 11 is driven will be described with reference to FIGS.

  FIG. 3 is a graph showing the opening characteristics of the nozzle vane 20 of the first embodiment. That is, the nozzle vane 20 is gradually opened with a characteristic curve as shown in FIG. 3 from the closed state as the engine speed increases. In such an opening degree characteristic of the nozzle vane 20, the relationship between the supercharging pressure, the turbine back pressure, and the hydraulic pressure with respect to the engine rotational speed has characteristics as shown in FIG. 4. That is, the supercharging pressure generated by the rotation of the compressor wheel 16 shows a characteristic curve that rises relatively abruptly as the engine speed increases and then gently falls. On the other hand, although the turbine back pressure based on the exhaust gas increases with an increase in the engine speed, the initial pressure is lower than the supercharging pressure and shows a characteristic curve with a gentle increase compared to the supercharging pressure. Therefore, the supercharging pressure prevails over the turbine back pressure in the low rotation range, and the turbine back pressure prevails in the high rotation range around 4000 rpm.

  As a result, the rotor shaft 17 of the turbocharger 11 of the first embodiment is applied with a force (thrust force) for moving in the thrust direction with the characteristics shown in FIG. Under such characteristics, the rotor shaft 17 moves toward the compressor wheel 16 as shown in FIG. 6 due to the supercharging pressure in the low rotation range, and the side surface of the thrust bearing 26 contacts the T surface of the bushing 34. As shown in FIG. 5, the thrust force on the compressor wheel 16 side peaks and attenuates around 2000 rpm, and the direction of the thrust force changes around 4000 rpm.

  As shown in FIG. 6, the rotor shaft 17 moves toward the turbine wheel 15 due to the turbine back pressure, and the side surface of the thrust bearing 26 is in contact with the C surface of the bushing 35 in the high rotation region exceeding 4000 rpm. As shown in FIG. 5, the thrust force on the turbine wheel 15 side becomes a peak near 6000 rpm and attenuates.

In FIG. 6, the gap formed between the bushings 34, 35 and the end face of the thrust bearing 26 is shown exaggerated more than the actual for the explanation of the invention.
Now, the lubricating oil is always supplied to the main oil supply passage 38 of the thrust bearing 26 during engine rotation. The lubricating oil mainly lubricates the outer peripheral surface of the bearing metal 33 in a pressurized state.

  Further, when the engine speed does not reach 4000 rpm, the ECU 30 controls the actuator 29 so as to supply the lubricating oil to the first auxiliary oil passage 39 and close the second auxiliary oil passage 40. That is, in the opening characteristic of the nozzle vane 20 of the first embodiment, the thrust bearing 26 is in contact with the T surface of the bushing 34 in the low rotation range. The hydraulic pressure on the C surface side of the bushing 35 in which the gap is generated is released. The T surface side of the bushing 34 (the side in contact with the side surface of the thrust bearing 26) is lubricated while being pressurized by the lubricating oil supplied from the first sub oil supply passage 39. On the other hand, since the second sub oil supply passage 40 is closed, the pressurized lubricating oil is not supplied to the gap on the C surface side (the non-contact side with the side surface of the thrust bearing 26).

  Further, when the engine rotation speed exceeds 4000 rpm, the ECU 30 controls the actuator 29 so that the lubricating oil is supplied to the second auxiliary oil supply passage 40 and the first auxiliary oil supply passage 39 is closed. That is, in the high rotation range, the side surface of the thrust bearing 26 is in contact with the C surface of the bushing 35 contrary to the above, so that pressurized lubricating oil is supplied to the contact surface and a slight gap is generated in the bushing 34. Release the hydraulic pressure on the T side.

  Contrary to the above, the C surface side (the contact side with the side surface of the thrust bearing 26) of the bushing 35 is lubricated in a state of being pressurized by the lubricating oil supplied from the second sub oil supply passage 40. On the other hand, since the first auxiliary oil supply passage 39 is closed, the pressurized lubricating oil is not supplied to the gap on the T surface side (the non-contact side with the side surface of the thrust bearing 26).

According to the turbocharger 11 of the first embodiment described above, the following effects can be obtained.
(1) In the first embodiment, lubricating oil is always supplied in a pressurized state from the opening 38 a of the main oil supply passage 38 to the outer peripheral surface of the bearing metal 33 of the rotor shaft 17, and the friction of the rotor shaft 17 against the thrust bearing 26 is reduced. Is secured. In general, since the hydraulic pressure of the lubricating oil supplied to the thrust bearing 26 is set to a low pressure, it is difficult for the lubricating oil to rotate on the C and T surfaces of the bushings 34 and 35 only by the main oil supply passage 38. In this respect, in the present embodiment, the first and second auxiliary oil supply passages 39 and 40 are disposed near the C surface and the T surface of the thrust bearing 26, so that the thrust bearing 26 contacting the C surface and the T surface is arranged. Lubricating oil will be sufficiently supplied also to the side surfaces.
(2) Due to the change in the direction of the thrust force applied to the rotor shaft 17, the side surface of the thrust bearing 26 comes in contact with and separates from the C surface and the T surface. Lubricating oil is not supplied from the auxiliary oil supply passages 39 and 40 on the surface side that is supplied and separated. Therefore, efficient lubrication is performed on the contact portion between the thrust bearing and the bushings 34 and 35, and the frictional resistance due to the hydraulic pressure in the portion where a gap is formed between the both 34 and 35 is eliminated. Can do. Therefore, it contributes to the turbo efficiency of the turbocharger 11.
(3) The openings 39 a and 40 a of the auxiliary oil supply passages 39 and 40 are opened to large diameter passages 37 b and 37 c having a large cross-sectional area in the lubricating oil flow passage 37. The lubricating oil supplied from the openings 39a and 40a to the large diameter passages 37b and 37c is less likely to flow to the opposite side beyond this portion due to the passage resistance of the lubricating oil in the small diameter passage 37a having a small cross-sectional area. Therefore, the lubricating oil supplied from the openings 39a and 40a to the lubricating oil passage 37 can be efficiently distributed to the lubrication points.
(4) Since the lubricating oil is always supplied from the oil supply passage 38, the lubrication is insufficient when, for example, the auxiliary lubricating passage to be blocked is switched between the first auxiliary oil passage 39 and the second auxiliary oil passage 40. Can be prevented from occurring.

(Embodiment 2)
The second embodiment will be described with reference to FIG. The basic configuration of the second embodiment is the same as that of the first embodiment, and only the configuration of the thrust bearing 26 and the configuration of the switching valve 27 are different. For this reason, the following description will be focused on the parts different from the first embodiment.

  In the thrust bearing 26 of the second embodiment, unlike the first embodiment, the small diameter passage 37 a is not formed in the lubricating oil passage 37. The cross-sectional area of the lubricating oil passage 37 is the same as that of the large diameter passages 37b and 37c. Moreover, the 1st and 2nd main oil supply channel | paths 41 and 42 are arrange | positioned in the thrust direction front and back. Unlike Embodiment 1, since there are two oil supply passages, the switching valve 27 of Embodiment 2 is a two-way switching valve (control valve).

  In the turbocharger 11 of the second embodiment, unlike the first embodiment, the main oil supply passage 38 is not provided, but the lubricating oil can be supplied to the outer peripheral surface of the bearing metal 33 as in the first embodiment. In addition, efficient lubrication is performed on the contact portion between the thrust bearing and the bushings 34 and 35, and the frictional resistance due to the hydraulic pressure in the portion where a gap is formed between the both 34 and 35 is eliminated. Can do.

(Embodiment 3)
The third embodiment will be described with reference to FIG. The basic configuration of the third embodiment is the same as that of the first embodiment, and only the configuration of the thrust bearing 26 and the configuration of the switching valve 27 are different. For this reason, the following description will be focused on the parts different from the first embodiment.

  In the thrust bearing 26 of the third embodiment, unlike the first embodiment, the small diameter passage 37 a is not formed in the lubricating oil passage 37. The cross-sectional area of the lubricating oil passage 37 is the same as that of the large diameter passages 37b and 37c. Further, one main oil supply passage 43 is arranged to be biased toward the turbine wheel 15 side. Unlike the first embodiment, since the number of oil supply passages is one, the switching valve 27 is unnecessary. Further, since there is only one main oil supply passage 43, the port for supplying the lubricating oil cannot be switched as in the first embodiment.

  In the turbocharger 11 of the third embodiment as well, the lubricating oil can be supplied to the outer peripheral surface of the bearing metal 33 as in the first embodiment, and in particular, since it is biased toward the turbine wheel 15 side, When the T surface of the bushing 34 comes into contact, the contact resistance can be reduced.

(Embodiment 4)
The fourth embodiment will be described with reference to FIG. The basic configuration of the fourth embodiment is the same as that of the first embodiment, and only the configuration of the thrust bearing 26 is different. For this reason, the following description will be focused on the parts different from the first embodiment.

  In the thrust bearing 26 of the fourth embodiment, unlike the first embodiment, the small diameter passage 37 a is not formed in the lubricating oil passage 37. However, the cross-sectional area of the lubricating oil passage 37 is the same as that of the small diameter passage 37a. Further, the first and second auxiliary oil supply passages 39, 40 are bent 90 degrees laterally, and the openings 39a, 40a open to the side surface of the thrust bearing 26 and face the T surface and the C surface.

  In the turbocharger 11 according to the fourth embodiment, in addition to the effects of the first embodiment, the opening portions 39a and 40a of the first and second auxiliary oil supply passages 39 and 40 open to the side surface of the thrust bearing 26. Therefore, it is possible to receive the supply of lubricating oil more directly when coming into contact with the T-plane and C-plane, and to quickly reduce the contact resistance.

(Embodiment 5)
The fifth embodiment will be described with reference to FIG. The basic configuration of the fifth embodiment is the same as that of the first embodiment, and only the configuration of the thrust bearing 26 and the configuration of the switching valve 27 are different. For this reason, the following description will be focused on the parts different from the first embodiment.

  In the thrust bearing 26 of the fifth embodiment, one main oil supply passage 43 is disposed in the center of the thrust bearing 26 in the thickness direction (same as the thrust direction) (similar to the main oil supply passage 38 of the first embodiment in this respect). Further, the first and second branch oil supply passages 44 and 45 are formed by branching in a cross shape along the thrust direction of the rotor shaft 17 at a position near the bearing metal 33. Openings (oil supply ports) 44a and 45a of both branch oil supply passages 44 and 45 open to the side surface of the thrust bearing 26 and face the T surface and the C surface.

  In this embodiment, the first branch oil supply passage 44 and the second branch oil supply passage 45 may be formed to have the same passage cross-sectional area (for example, the area of the openings 44a and 45a). These may be formed differently. When the passage cross-sectional areas are made different, for example, the passage cross-sectional area of the branch oil supply passages 44 and 45 that needs to secure a larger amount of oil supply is set larger.

  In the turbocharger 11 of the fifth embodiment as well, the lubricating oil can be supplied to the outer peripheral surface of the bearing metal 33 as in the first embodiment. Further, since the openings 44a and 45a of the first and second branch oil supply passages 44 and 45 are open on the side surfaces of the thrust bearing 26, the lubricant oil is supplied more directly when contacting the T and C surfaces. It is also possible to quickly reduce the contact resistance.

(Embodiment 6)
The sixth embodiment will be described with reference to FIG. The basic configuration of the sixth embodiment is the same as that of the first embodiment, and only the configuration of the thrust bearing 26 is different. For this reason, the following description will be focused on the parts different from the first embodiment.

  In the thrust bearing 26 according to the sixth embodiment, the first and second sub oil supply passages 39 and 40 are branched at positions close to the bearing metal 33 to form first and second branch oil supply passages 46 and 47. Openings (oil supply ports) 46a, 47a of the oil supply passages 46, 47 open to the side surface of the thrust bearing 26 and face the T surface and the C surface.

  In the turbocharger 11 of the sixth embodiment, in addition to the effects of the first embodiment, the openings 46a and 47a of the first and second branch oil supply passages 46 and 47 open to the side surface of the thrust bearing 26. Therefore, it is possible to receive the supply of lubricating oil more directly when coming into contact with the T-plane and C-plane, and to quickly reduce the contact resistance.

(Embodiment 7)
The seventh embodiment will be described with reference to FIG. The basic configuration of the seventh embodiment is the same as that of the first embodiment, and only the configuration of the thrust bearing 26 and the configuration of the switching valve 27 are different. For this reason, the following description will be focused on the parts different from the first embodiment.

  In the thrust bearing 26 of the third embodiment, a branch oil supply passage 49 is formed that branches from the middle of one main oil supply passage 48 toward the turbine wheel 15 side. The branch oil supply passage 49 is further bent downward, and an opening (oil supply port) 49a is opened in the large diameter passage 37b. Unlike the first embodiment, since the number of oil supply passages is one, the switching valve 27 is unnecessary. Further, since there is only one main oil supply passage 48, the port for supplying the lubricating oil cannot be switched as in the first embodiment.

  In the turbocharger 11 of the seventh embodiment as well, the lubricating oil can be supplied to the outer peripheral surface of the bearing metal 33 as in the first embodiment, and in particular, since it is biased toward the turbine wheel 15 side, When the T surface of the bushing 34 comes into contact, the contact resistance can be reduced.

It should be noted that the present invention can be modified and embodied as follows.
The above embodiments are merely examples, and it is possible to freely configure thrust bearings having other shapes within the scope not departing from the gist of the present invention.

  The switching valve 27 only switches between opening and closing the oil supply passage, but a flow rate control valve capable of adjusting the supply amount may be combined.

Sectional drawing which shows the structure of the turbocharger of Embodiment 1 of this invention. FIG. 3 is a partially enlarged cross-sectional view in the vicinity of a thrust bearing according to the first embodiment. The graph which shows the opening characteristic of a nozzle. The graph explaining the relationship between engine rotation speed, supercharging pressure, turbine back pressure, and hydraulic pressure. 5 is a graph for explaining a change in thrust force in the graph characteristics of FIG. 4. The conceptual diagram explaining the relationship of the motion of the thrust direction of a rotor shaft, and a thrust bearing. (A)-(f) is the elements on larger scale of the thrust bearing of other embodiment. (A) is a fragmentary sectional view which shows the conventional turbocharger, (b) And (c) is an expanded partial sectional view which shows the conventional thrust bearing.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Turbocharger, 15 ... Turbine wheel, 16 ... Compressor wheel, 17 ... Roller shaft, 26 ... Thrust bearing, 27 ... Switching valve (control valve), 38, 41, 42, 43, 48 ... Main oil supply path, 39, 40 ... Sub-oil supply passage, 44, 45, 46, 47, 49 ... Branch oil supply passage, 38a, 43a, 48a, 45a, 46a, 47a, 49a ... Opening (oil supply port).

Claims (17)

A turbine wheel and a compressor wheel are connected to a shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing to restrict the movement of the shaft in the thrust direction and allow the shaft to rotate in the circumferential direction. In the turbocharger in which the compressor wheel is driven to rotate by the rotation of the turbine wheel rotated by the engine, and fresh air compressed by the compressor wheel is supplied to the engine.
A main oil supply passage for supplying oil to the outer peripheral surface of the shaft is formed in the thrust bearing, and an oil supply port of the main oil supply passage is provided on either the turbine wheel side or the compressor wheel side of the thrust bearing. A turbocharger characterized by opening at a biased position. A turbine wheel and a compressor wheel are connected to a shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing to restrict the movement of the shaft in the thrust direction and allow the shaft to rotate in the circumferential direction. In the turbocharger in which the compressor wheel is driven to rotate by the rotation of the turbine wheel rotated by the engine, and fresh air compressed by the compressor wheel is supplied to the engine.
In the thrust bearing, a fuel supply port forms a main oil supply passage facing the outer peripheral surface of the shaft, a branch oil supply passage branched from the main oil supply passage is formed, and the oil supply port of the branch oil supply passage is connected to the thrust bearing. The turbocharger is configured to open at a position biased to either the turbine wheel side or the compressor wheel side.   3. The turbocharger according to claim 2, wherein an oil supply port of the branch oil supply passage opens toward one of a side surface on the turbine wheel side and a side surface on the compressor wheel side of the thrust bearing. A turbine wheel and a compressor wheel are connected to a shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing to restrict the movement of the shaft in the thrust direction and allow the shaft to rotate in the circumferential direction. In the turbocharger in which the compressor wheel is driven to rotate by the rotation of the turbine wheel rotated by the engine, and fresh air compressed by the compressor wheel is supplied to the engine.
The thrust bearing forms a main oil supply passage with an oil supply port facing the outer peripheral surface of the shaft, and also forms first and second branch oil supply passages branched from the main oil supply passage. The oil supply port of the branch oil supply passage is opened at a position biased toward the turbine wheel of the thrust bearing, and the oil supply port of the second oil supply passage is opened at a position biased toward the compressor wheel. Features a turbocharger.   The oil supply port of the first branch oil supply passage faces the side surface on the turbine wheel side of the thrust bearing, and the oil supply port of the second branch oil supply passage opens on the side surface on the compressor wheel side. The turbocharger according to claim 4. A turbine wheel and a compressor wheel are connected to a shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing to restrict the movement of the shaft in the thrust direction and allow the shaft to rotate in the circumferential direction. In the turbocharger in which the compressor wheel is driven to rotate by the rotation of the turbine wheel rotated by the engine, and fresh air compressed by the compressor wheel is supplied to the engine.
In the thrust bearing, a main oil supply passage having an oil supply port facing the outer peripheral surface of the shaft and a sub oil supply passage independent of the main oil supply passage are formed, and the oil supply port of the sub oil supply passage is connected to the oil supply port of the thrust bearing. The turbocharger is configured to be opened at a position biased to either the turbine wheel side or the compressor wheel side.   The turbocharger according to claim 6, wherein an oil supply port of the auxiliary oil supply passage opens toward one of a side surface on the turbine wheel side and a side surface on the compressor wheel side of the thrust bearing.   The flow rate of lubricating oil supplied to the auxiliary oil supply passage is made variable based on a change in operating condition parameter that causes a change in the position of the shaft in the thrust direction relative to the thrust bearing. Item 8. The turbocharger according to Item 6 or 7. A turbine wheel and a compressor wheel are connected to a shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing to restrict the movement of the shaft in the thrust direction and allow the shaft to rotate in the circumferential direction. In the turbocharger in which the compressor wheel is driven to rotate by the rotation of the turbine wheel rotated by the engine, and fresh air compressed by the compressor wheel is supplied to the engine.
In the thrust bearing, there are formed a main oil supply passage having an oil supply port facing the outer peripheral surface of the shaft, and first and second sub oil supply passages independent of the main oil supply passage. A turbocharger characterized in that an oil supply port is opened at a position biased toward the turbine wheel of the thrust bearing, and an oil supply port of a second auxiliary oil supply passage is opened at a position biased toward the compressor wheel. .   The oil supply port of the first sub oil supply passage faces a side surface of the thrust bearing on the turbine wheel side, and the oil supply port of the second sub oil supply passage opens on a side surface of the compressor wheel. The turbocharger according to claim 9.   The flow rate of the lubricating oil supplied to the first and second auxiliary oil supply passages is made variable based on a change in operating condition parameters that cause a change in the position of the shaft in the thrust direction relative to the thrust bearing. The turbocharger according to claim 9 or 10, characterized in that   12. A control valve connected to the first and second auxiliary oil supply passages and distributing the lubricating oil supplied from a lubricating oil supply source to the first and second auxiliary oil supply passages. The turbocharger described in 1. A turbine wheel and a compressor wheel are connected to a shaft so as to be integrally rotatable, and the shaft is supported by a thrust bearing to restrict the movement of the shaft in the thrust direction and allow the shaft to rotate in the circumferential direction. In the turbocharger in which the compressor wheel is driven to rotate by the rotation of the turbine wheel rotated by the engine, and fresh air compressed by the compressor wheel is supplied to the engine.
The first and second main oil supply passages are formed in the thrust bearing so that the oil supply ports face the outer peripheral surface of the shaft, and the oil supply port of the first main oil supply passage is connected to the turbine wheel side of the thrust bearing. The turbocharger is characterized in that it is opened at a position biased to a position where the oil supply port of the second main oil supply passage is opened at a position biased toward the compressor wheel.   A first branch oil supply passage is formed in the first main oil supply passage, and a second branch oil supply passage is formed in the second main oil supply passage, and an oil supply port of the first branch oil supply passage is formed. 14. The turbocharger according to claim 13, wherein the turbocharger faces a side surface of the thrust bearing on the turbine wheel side, and an oil supply port of the second branch oil supply passage opens on a side surface on the compressor wheel side.   The flow rate of the lubricating oil supplied to the first and second main oil supply passages is made variable based on a change in operating condition parameter that causes a change in the position of the shaft in the thrust direction with respect to the thrust bearing. The turbocharger according to claim 13 or 14, characterized in that   16. A control valve is connected to the first and second main oil supply passages and includes a control valve that distributes the lubricating oil supplied from a lubricating oil supply source to the first and second main oil supply passages. The turbocharger described in 1.   Concerning the flow passage formed in the thrust direction formed between the thrust bearing and the outer peripheral surface of the shaft, the flow passage is configured so that a portion having a large cross-sectional area and a portion having a small cross-sectional area are formed, The turbocharger according to claim 1, wherein the turbocharger is opened at a portion having a large cross-sectional area.

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