JP4367628B2 - Electric motor integrated turbocharger - Google Patents

Description

  The present invention relates to a turbocharger for an internal combustion engine, and more particularly, to a turbocharger in which an auxiliary drive motor is integrated.

  In a turbocharger that performs supercharging operation of intake air in an internal combustion engine, generally, a turbine wheel that is provided in an exhaust passage and rotates by exhaust gas, and a compressor wheel that is provided in the intake passage and performs supercharging operation of intake air by rotation, However, the structure provided in the both ends of the axis | shaft is taken.

  In such a turbocharger, the shaft rotates at a high speed and the turbine wheel side is exposed to a high-temperature environment. Therefore, a ball bearing using ceramic balls is used as the bearing device, and air is lubricated. Various proposals have been made, such as one in which the shaft is supported by two fluid dynamic bearings that are fluids (see, for example, Patent Document 1). It is excellent because it can be easily cooled and a damper effect can be expected. An example is shown in FIG.

  In the example shown in FIG. 2, a shaft 23 having a turbine wheel 21 attached to one end and a compressor wheel 22 attached to the other end is supported by two floating bushes 24 and 25 with a predetermined span open, and on the compressor wheel 22 side. A thrust bearing 26 is provided adjacent to the floating bush 25 (see Non-Patent Document 1, for example).

  The floating bushes 24, 25 have a clearance with respect to both the shaft 23 and the housing 27, have a through hole that extends from the outer periphery to the inner periphery, and are forcibly supplied through an oil supply passage 27 a provided in the housing 27. The oil also flows into the inner peripheral side through the through hole, and rotates relative to both the shaft 23 and the housing 27 while being lubricated. The thrust bearing 26 is constituted by a collar 26a fixed to the shaft 23 and a disk-like member 26b fixed to the housing 27 side, and lubricating oil is forcibly supplied between them, so that the disk is The generation of an oil film is promoted by the action of the taper land formed on the shaped member 26b.

  By the way, in general, a turbocharger has a phenomenon called a so-called turbo lag in which a supercharging operation is not effectively performed unless the rotation speed of the internal combustion engine reaches a certain rotation speed. In addition, a permanent magnet is attached to the outer periphery of the shaft of the turbocharger, and a motor stator is disposed on the outer side of the turbocharger so that the shaft is used as a motor rotor for auxiliary electric drive when the rotational speed of the internal combustion engine is low. Chargers are known (see, for example, Patent Document 1).

An attempt has been made to apply a floating bush having the above-described advantages to support the shaft of such a motor-integrated turbocharger, and an example is shown in FIG. 3 (see, for example, Non-Patent Document 2). In this example, a shaft 33 having a turbine wheel 31 and a compressor wheel 32 attached to both ends is supported by two floating bushes 34 and 35, and a permanent magnet 36 forming a motor rotor and a shaft of a motor stator 37 disposed outside the permanent magnet 36 are provided. As shown in the figure, the directional position is between the compressor wheel 33 and the floating bush 35, and a mechanical seal 38 is disposed between the permanent magnet 36 and the floating bush 35.
Tsutomu Gomi “Automotive Engineering Complete Book 4 Gasoline Engine” Sankai-do Publishing, 1980 p. 167-169 JP 58-37319 A JP-A-7-259576 SMShahed "Smart Boosting System e-Turbo (TM) and e-Charger (TM)" New Frontier? "[Online] August 6-9,2001 US Department of Energy Diesel Engine Emission Reduction Workshop [February 10, 2004 ] Internet <URL;http://www.osti.gov/fcvt/deer2001/shaheds.pdf>

  By the way, in the turbocharger in which the electric motor is integrated so as to eliminate the turbo lug, the structure shown in FIG. 3 adopting the floating bush having many advantages described above including the cooling performance as a bearing for supporting the shaft is provided. Although this is the most practical, in this structure, the lubricating oil for forcibly lubricating the floating bush leaks to the motor to eliminate the risk of leakage, and at the same time, the lubricating oil leaks to the compressor wheel 32 side and the engine efficiency In order to prevent the deterioration of the motor, the mechanical seal 38 is provided between the two floating bushes 34 and 35 and the permanent magnet 36 constituting the rotor of the electric motor. In this structure, the motor rotor and the compressor comprising the permanent magnet 36 are provided. The problem that the wheel 33 is substantially cantilevered and the rotation balance of the shaft 33 is deteriorated. A.

  The present invention has been made in view of the above circumstances, and uses a floating bush with good cooling performance as a bearing, eliminates the possibility of lubricating oil leaking to the compressor wheel side, and uses a shaft radial bearing as a rotor of an electric motor. It is an object of the present invention to provide a motor-integrated turbocharger that can be disposed on both sides of the motor and can provide a good rotational balance of the shaft.

  In order to solve the above-described problems, an electric motor-integrated turbocharger according to the present invention includes a turbine wheel disposed in an exhaust passage of an internal combustion engine and a compressor wheel disposed in an intake passage at both ends of the shaft. It is attached and the rotational energy of the turbine wheel due to the exhaust gas is transmitted to the compressor wheel to perform the intake supercharging operation. On the shaft, a permanent magnet is attached between the turbine wheel and the compressor wheel to form a motor rotor. In the electric motor-integrated turbocharger in which the motor stator is arranged on the outer side, of the radial bearings supporting the shaft, the turbine wheel side is a floating bush to which lubricating oil is circulated and the compressor wheel side is A bearing that does not require the supply of lubricating oil. Together with the motor rotor during receiving it is formed, characterized by the seal for sealing is provided a lubricating oil between the motor rotor and the floating bush (claim 1).

  Here, in this invention, the structure (Claim 2) which makes the said bearing by the side of the said compressor wheel the dynamic pressure bearing which uses air as a lubricating fluid is employable suitably.

  The present invention is a compressor in which a floating bush that is excellent in cooling performance due to forced circulation of lubricating oil is arranged on the turbine wheel side where the temperature is likely to rise, and the leakage of lubricating oil affects engine efficiency. The wheel side is provided with a bearing that is less likely to leak oil and does not require the supply of lubricating oil, and the motor rotor is placed between these two bearings to achieve the intended purpose. is there.

  In other words, a floating bush with excellent cooling performance is provided on the turbine wheel side exposed to high-temperature exhaust gas by circulating supply of lubricating oil, while it is necessary to supply lubricating oil to the compressor wheel side where the temperature rise is small. Place no bearing and prevent the lubricating oil from leaking to the compressor wheel side. The motor rotor is disposed between these two bearings, and a seal is disposed between the motor rotor and the floating bush to prevent the lubricant from leaking to the motor rotor side while maintaining a good rotational balance. In addition, since the floating bush is interposed between the turbine wheel and the motor rotor, the heat of the turbine wheel is hardly transmitted to the motor rotor, and is not easily affected by the temperature rise of the electric motor.

  In the present invention, the bearing disposed on the compressor wheel side is not particularly limited as long as it does not require supply of lubricating oil. For example, a ceramic ball bearing can be used. By adopting a hydrodynamic bearing that uses air as a lubricating fluid as in the invention, no grease is required as in the case of using a ball bearing, and the hydrodynamic bearing that uses air as a lubricating fluid has a sealing effect. Therefore, oil leakage to the compressor wheel can be prevented more reliably.

  According to the present invention, a floating bush that is forcedly lubricated and has excellent cooling performance is disposed on the turbine wheel side that is likely to be heated to high temperatures due to exhaust, and supply of lubricating oil is required on the compressor wheel side that is greatly affected by leakage of lubricating oil. In this structure, a motor rotor is disposed between the two bearings and a seal is disposed between the motor rotor and the floating bush, so that the heat of the turbine wheel, which is heated by exhaust, is effectively cooled. This can prevent transmission to the motor rotor and reduce its output, and can effectively prevent the lubricating oil from leaking to the compressor wheel, and the motor rotor is disposed between the two bearings. Therefore, a turbocharger with excellent rotation balance can be obtained.

  Further, as in the invention according to claim 2, by making the bearing on the compressor wheel side a dynamic pressure bearing using air as a lubricating fluid, leakage of lubricating oil to the compressor wheel side can be prevented more reliably. Further, it is possible to prevent the engine efficiency from being lowered due to the lubricating oil mixed in the intake air.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an axial parallel sectional view showing the configuration of the embodiment of the present invention.

  A turbine wheel 2 is provided on one end side of the shaft 1, and a compressor wheel 3 is provided on the other end side. The turbine wheel 2 is placed in the exhaust passage of the engine and is rotated by exhaust. The compressor wheel 3 is placed in the intake passage of the engine, and the rotation of the turbine wheel 2 is transmitted through the shaft 1, and the air is compressed by this rotation and supplied to the engine. The shaft 1 on which both the turbine wheel 2 and the compressor wheel 3 are provided at both ends has two radial bearings, that is, a floating bush 5 and a hydrodynamic bearing 6 using air as a lubricating fluid. And one thrust bearing 7 is rotatably accommodated.

  Of the two radial bearings, the floating bush 5 is provided on the turbine wheel 2 side, and the dynamic pressure bearing 6 is provided on the compressor wheel 3 side. Further, a thrust bearing 7 is disposed adjacent to the floating bush 5 on the opposite side to the turbine wheel 2. The floating bush 5 and the thrust bearing 7 are the same as those shown in FIG. 2 described above, and the lubricating oil is forcibly circulated and supplied through the lubricating oil supply passage 4 a formed in the housing 4. Further, a water jacket 4b is formed in the housing 4 corresponding to the position of the floating bush 5, and when the cooling water flows through the water jacket 4b, the floating bush 5 and the thrust bearing 7 are supplied to these. The lubricating oil is cooled. A piston ring type mechanical seal 8 is provided between the turbine wheel 2 and the floating bush 5.

  The hydrodynamic bearing 6 includes a sleeve 6a that is press-fitted and fixed to the shaft 1, and a bush 6b that is attached to the housing 4 via a seal ring 6c with a predetermined gap formed outside the sleeve 6a. A known herringbone-shaped dynamic pressure groove is formed on the outer peripheral surface of the sleeve 6a. When the shaft 1 rotates, a dynamic pressure of air is generated between the bush 6b and the air film by the pumping action of the dynamic pressure groove. And the fluid film keeps the sleeve 6a and the bush 6b in a non-contact state.

  A mechanical seal 9 made of a carbon material is provided adjacent to the thrust bearing 7 and on the opposite side of the floating bush 5. A motor rotor 10 is provided between the mechanical seal 9 and the hydrodynamic bearing 6 and has a permanent magnet 10 a fixed to the outer periphery of the shaft 1. A motor stator 11 fixed to the housing 4 is disposed outside the motor rotor 10. The motor stator 11 and the motor rotor 10 constitute a brushless motor, and a current flows through each coil 11 a of the motor stator 11. The motor rotor 10 is thus configured such that the shaft 1 rotates.

  According to the above embodiment, the lubricating oil is forcibly supplied to the turbine wheel 2 side that becomes high due to the rotation given by the high-temperature exhaust gas, and the cooling performance is combined with the water jacket 4b. Since the high floating bush 5 is disposed, the turbine wheel 2 and its vicinity can be cooled effectively, and a damper effect can be expected. Moreover, on the side of the compressor wheel 3 that adversely affects the engine performance due to the leakage of lubricating oil, there is disposed a hydrodynamic bearing 6 using air as a lubricating fluid, which does not require lubricating oil and has a sealing effect by itself. As a result, there is no risk that lubricant will enter the intake air of the engine. And while using the floating bush 5 which has cooling performance and a damper effect as mentioned above, the electric motor for carrying out auxiliary drive of a turbocharger is arrange | positioned between two bearings, and the favorable rotation balance is obtained.

  In the above embodiment, the example in which the dynamic pressure bearing 6 using air as a lubricating fluid is provided on the compressor wheel 3 side has been described. Instead of the dynamic pressure bearing 6, for example, ceramic is used as a rolling element. Even if a grease-lubricated rolling bearing is used, the same effect as described above can be obtained.

It is an axial parallel sectional view of an embodiment of the invention. It is an axial parallel sectional view showing a configuration example of a conventional turbocharger using two floating bushes as a radial bearing. It is an axis parallel sectional view showing an example of composition of a conventional motor-integrated turbocharger equipped with an auxiliary drive motor and using a floating bush.

Explanation of symbols

1 shaft 2 turbine wheel 3 compressor wheel 4 housing 4a lubricating oil supply path 4b water jacket 5 floating bush 6 dynamic pressure bearing 6a sleeve 6b bush 7 thrust bearing 8, 9 mechanical seal 10 motor rotor 10a permanent magnet 11 motor stator 11a coil

Claims (2)

A turbine wheel disposed in the exhaust passage of the internal combustion engine and a compressor wheel disposed in the intake passage are respectively attached to both ends of the shaft, and transmit rotational energy of the turbine wheel by the exhaust gas to the compressor wheel. In the turbocharger with an integrated motor, in which a turbo magnet is formed by attaching a permanent magnet to the shaft between the turbine wheel and the compressor wheel to form a motor rotor, and a motor stator is arranged on the outside of the shaft.
Of the radial bearings that support the shaft, the turbine wheel side is a floating bush to which lubricating oil is circulated and supplied, and the compressor wheel side is a bearing that does not require supply of lubricating oil. A motor-integrated turbocharger, wherein the motor rotor is formed between the motor rotor and a seal for sealing lubricating oil between the motor rotor and the floating bush.   The motor-integrated turbocharger according to claim 1, wherein the compressor wheel bearing is a hydrodynamic bearing using air as a lubricating fluid.

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