JP2008267463A - Floating bearing structure - Google Patents

Abstract

A floating bearing structure capable of suppressing the occurrence of fore vibration is provided.
A turbocharger 1 houses a shaft 7 extending in one direction, a cylindrical floating bush 24 surrounding the shaft 7 and having an inner peripheral surface facing the outer peripheral surface of the shaft 7, and the floating bush 24. And a center housing 36 provided with an internal space. The floating bush 24 is provided with a through hole 124 that penetrates the bush in the radial direction from the outer peripheral surface to the inner peripheral surface. The center housing 36 is provided with a first oil supply path 136 that supplies the oil 100 to the through hole and three or more second oil supply paths 236. The second oil supply passages 236 are arranged at a distance from each other in the circumferential direction of the outer peripheral surface.
[Selection] Figure 4

Description

  The present invention relates to a floating bearing structure, and more particularly to a floating bearing structure in which a shaft is held and lubricated with oil.

Conventionally, a floating bearing structure is disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-332864 (Patent Document 1).
JP 2002-332864 A

  In the conventional floating bearing structure, a technology for suppressing the whirl vibration by adjusting the viscosity of the lubricating oil according to the operation region is disclosed.

  However, the conventional technique has a problem that the control of the oil viscosity is low and the control of the whirl vibration cannot be sufficiently suppressed.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a floating bearing structure capable of suppressing whirl vibration.

  The floating bearing structure according to the present invention includes a shaft extending in one direction, a cylindrical floating bush surrounding the shaft and having an inner peripheral surface facing the outer peripheral surface of the shaft, and an internal space for housing the floating bush. And an oil is interposed between the outer peripheral surface of the shaft and the inner peripheral surface of the floating bush, and between the outer peripheral surface of the floating bush and the inner peripheral surface of the housing. A through hole that penetrates the floating bush in the radial direction from the outer peripheral surface to the inner peripheral surface is provided, and the housing has a first oil supply path that supplies oil to the through hole and an outer peripheral surface of the floating bush. Three or more second oil supply paths for injecting oil are provided, and the three or more second oil supply paths are arranged at a distance from each other in the circumferential direction of the outer peripheral surface.

  In the floating bearing structure configured as described above, since the first oil supply path for supplying oil to the through hole is provided, the oil is supplied from the outer peripheral surface to the inner peripheral surface through the through hole, and on the inner peripheral surface side. The shaft can be held.

  Further, since three or more second oil supply paths are provided and are spaced apart from each other in the circumferential direction of the outer peripheral surface, when the whirl vibration occurs and the shaft and the bush approach the housing side, The oil supplied from the second oil supply path hits the outer peripheral surface of the bush. Thereby, the bush is pushed back to the center position. Thereby, a whirl vibration can be prevented.

  Preferably, the second oil supply path injects oil toward the bush in a direction that prevents rotation of the bush. In this case, when the bush approaches the housing, oil is jetted from the second oil supply path toward the bush, thereby preventing the bush from rotating. Thereby, generation | occurrence | production of a whirl vibration can be suppressed by dropping a rotation speed temporarily.

  According to the present invention, a turbocharger that can suppress the occurrence of whirl vibration can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated. It is also possible to combine all the embodiments.

(Embodiment 1)
1 is a schematic configuration diagram showing a diesel engine system having a turbocharger having a floating bearing structure according to Embodiment 1 of the present invention. The diesel engine system shown in Fig. 1 combines a high-pressure common rail fuel injection system, a large-capacity electronically controlled EGR (Exhaust Gas Recirculation) cooler, and a DPNR (Diesel Particulate NOx Reduction) catalyst in order to achieve clean exhaust from the diesel engine. (Particulate Matter) and NOx are continuously and simultaneously reduced. In FIG. 1, an internal combustion engine (hereinafter referred to as an engine) 1000 is a four-cylinder diesel engine having a fuel supply system 1001, a combustion chamber 200, an intake system 300, and an exhaust system 400 as main parts. The number of cylinders is not particularly limited, and various shapes such as an in-line type, a V type, a W type, and a horizontally opposed type can be adopted as the shape of the engine. The DPNR 450 can be adopted even if it is a DPF (Diesel Particulate Filter) for regenerating PM.

  The fuel supply system 1001 includes a supply pump 110, a common rail 120, a fuel injection valve 130, a shielding valve 140, a metering valve 160, a fuel addition nozzle 170, an engine fuel passage 800, and an addition fuel passage 810.

  The supply pump 110 pumps up fuel from the fuel tank, raises the pumped fuel to a high pressure, and supplies the pumped fuel to the common rail 120 via the engine fuel passage 800. The common rail 120 functions as a pressure accumulation chamber that holds (accumulates) the high-pressure fuel supplied from the supply pump 110 at a predetermined pressure, and distributes the accumulated fuel to each fuel injection valve 130. The fuel injection valve 130 includes an electromagnetic solenoid therein, and is appropriately opened to inject and supply fuel to the combustion chamber 200.

  The supply pump 110 supplies a part of the fuel pumped from the fuel tank toward the fuel injection nozzle (reducing agent injection nozzle) 170 via the added fuel passage 810. In the addition fuel passage 810, a shielding valve 140 and a metering valve 160 are sequentially arranged from the supply pump 110 toward the fuel addition nozzle 170. The shielding valve 140 blocks the added fuel passage 810 in an emergency and stops the fuel supply. The metering valve 160 controls the pressure (fuel pressure) of the fuel supplied to the fuel addition nozzle 170. The fuel addition nozzle 170 is a mechanical on-off valve that opens when a fuel pressure (for example, 0.2 MPa) equal to or higher than a predetermined pressure is applied and injects fuel into the exhaust system 400 (exhaust port 410). That is, by controlling the upstream fuel pressure of the fuel addition nozzle 170 by the metering valve 160, desired fuel is injected and supplied (added) from the fuel addition nozzle 170 at an appropriate timing.

  The intake system 300 constitutes a passage (intake passage) for intake air supplied into each combustion chamber 200. The exhaust system 400 is configured by connecting various passage members such as an exhaust port 410, an exhaust manifold 420, a catalyst upstream side passage 430, and a catalyst downstream side passage 440 in order from upstream to downstream, and exhaust exhausted from each combustion chamber 200. A gas passage (exhaust passage) is formed.

  Further, the engine 1000 is provided with a variable capacity turbocharger 1. The turbocharger 1 has a structure in which a compressor wheel 34 and a turbine wheel assembly 22 are connected via a turbine shaft 7. The intake system compressor wheel 34 is exposed to the intake air in the intake system 300, and the turbine wheel assembly 22 is exposed to the exhaust system 400. The turbocharger 1 having such a configuration performs so-called supercharging in which the compressor wheel 34 is rotated and the intake pressure is increased by utilizing the exhaust pressure (exhaust flow) received by the turbine wheel assembly 22.

  In this embodiment, a variable capacity turbocharger 1 is shown, but a non-variable capacity turbocharger 1 may be used.

  In the intake system 300, the intercooler 310 also received by the turbocharger 1 forcibly cools the intake air whose temperature has been increased by the intake and intake. The throttle valve 320 provided further downstream than the intercooler 310 is an electronically controlled on-off valve whose opening degree can be adjusted in a stepless manner, and restricts the flow area of the intake air under a predetermined condition. It has a function of adjusting (reducing) the supply amount of intake air.

  Further, the engine 1000 is formed with an exhaust circulation passage (EGR passage) 600 that bypasses the upstream (intake system 300) and the downstream (exhaust system 400) of the combustion chamber 200. The EGR passage 600 has a function of returning a part of the exhaust to the intake system 300 as appropriate. The EGR passage 600 is opened and closed steplessly by electronic control, and an EGR valve 610 that can freely adjust an exhaust passage flowing through the passage, and an exhaust for passing (refluxing) the EGR passage 600 is cooled. An EGR cooler 620 is provided.

  In this embodiment, an engine having EGR is shown, but the turbocharger of the present invention can also be applied as a turbocharger of an engine not having EGR.

  In the exhaust system 400, a catalyst 450 constituted by DPNR is disposed downstream of the turbine wheel assembly 22 (the catalyst upstream side passage 430 and the catalyst downstream side passage 440). The catalyst 450 serves to reduce NOx and PM in the exhaust. Various sensors are attached to each part of the engine 1000, and signals related to the environmental conditions of each part and the operating state of the engine 1000 are output.

  Also, DPR and DPNR are not necessarily provided, and the turbocharger of the present invention can be applied as a turbocharger of an engine not provided with DPR and DPNR.

  For example, the rail pressure sensor 700 outputs a detection signal corresponding to the fuel pressure stored in the common rail 120. The fuel pressure sensor 710 outputs a detection signal corresponding to the pressure (fuel pressure) Bg of the fuel introduced into the metering valve 160 among the fuel flowing through the added fuel passage 810. The air flow meter 720 outputs a detection signal corresponding to the flow rate (intake amount) Ga of intake air downstream of the throttle valve 320 in the intake system 300. The air-fuel ratio (A / F) sensor 730 outputs a detection signal that continuously changes in accordance with the oxygen concentration in the exhaust gas downstream of the catalyst casing of the intake system 300. Similarly, the exhaust temperature sensor 740 outputs a detection signal corresponding to the exhaust temperature (exhaust temperature) Tex downstream of the catalyst casing of the exhaust system 400.

  Accelerator opening sensor 750 is attached to an accelerator pedal of engine 1000 and outputs a detection signal corresponding to the depression amount Acc of the pedal. The crank angle sensor 760 outputs a detection signal (pulse) every time the output shaft (crankshaft) of the engine 1000 rotates by a certain angle. Each of these sensors 700 to 760 is electrically connected to an electronic control unit ECU (also referred to as an engine control unit) 1100. ECU 1100 includes a CPU (Central Processing Unit), ROM, RAM and backup RAM, a timer, a counter, and the like, and these are bidirectional with an external input circuit and an external output circuit including an analog / digital (A / D) converter. Connected by bus.

  Next, the structure of the turbine will be described. FIG. 2 is a perspective view including a partial cross section of the turbocharger according to the first embodiment of the present invention. 3 is a cross-sectional view taken along line III-III in FIG. Referring to FIGS. 2 and 3, turbocharger 1 according to the first embodiment of the present invention is a variable nozzle turbocharger, and includes housing 201, turbine shaft 7 rotatably accommodated in housing 201, and The compressor wheel 34 and the turbine wheel assembly 22 are attached to the turbine shaft 7.

  The housing 201 is divided into a compressor housing 2, a center housing 36 and a turbine housing 48, and the compressor housing 2 and the turbine housing 48 are attached to both sides of the center housing 36. In the compressor housing 2, it is set as the shape which can take in air from a center part, and can discharge | release it outside. Specifically, air is introduced into the central portion of the compressor housing 2, and this air is accelerated and compressed in the outward direction (radial direction) by the rotating compressor wheel 34, and the compressed air is guided to the intec manifold. It is burned.

  A compressor wheel 34 is accommodated in the compressor housing 2. The compressor wheel 34 is fixed to the turbine shaft 7 and rotates together with the turbine shaft 7. The compressor wheel 34 is fixed to the turbine shaft 7 by a lock nut 35. The compressor wheel 34 is provided with a plurality of blades. When the compressor wheel 34 rotates, the blades are accelerated and compressed in the radial direction by centrifugal force.

  A seal ring collar 25 is disposed adjacent to the compressor wheel 34. The seal ring collar 25 has a shape surrounding the turbine shaft 7.

  The center housing 36 is provided at the center of the turbocharger 1. A thrust bearing 26 is disposed in the center housing 36. The thrust bearing 26 is a bearing for receiving a load in the thrust direction of the turbine shaft 7 and is lubricated by oil or the like.

  The center housing 36 is provided with a floating bush 24 as a floating bearing for holding the rotation of the turbine shaft 7. The floating bush 24 holds a load in the radial direction of the turbine shaft 7. An oil film exists between the floating bush 24 and the turbine shaft 7, and the floating bush 24 does not directly contact the turbine shaft 7. Further, there is an oil film between the floating bush 24 and the center housing 36, and the floating bush 24 is not in direct contact with the center housing 36.

  The floating bush 24 is positioned by a retainer ring 30. A drive mechanism 202 as a link mechanism is disposed in the center housing 36 and the turbine housing 48. The drive mechanism 202 includes a unison ring 45 housed in the link chamber 301, an arm 44 that is located on the inner peripheral side of the unison ring 45 and contacts the unison ring 45, and a nozzle plate 43 provided adjacent to the turbine housing 48. And a main arm 37 for driving a plurality of arms 44, a vane shaft 21 connected to the arms 44 for driving the nozzle vanes 42, and a nozzle plate 43 for holding the vane shafts 21.

  The drive mechanism 202 is a mechanism for adjusting the angles of the plurality of nozzle vanes 42. When the pin 40 is rotated by a predetermined angle, the rotation is transmitted to the nozzle vanes 42, and the nozzle vanes 42 are rotated. Has been. The pin 40 is connected to a drive link 41, and the drive link 41 is rotatable about a drive shaft 39. A bush 38 is provided on the outer periphery of the drive shaft 39, and the bush 38 is interposed between the drive shaft 39 and the center housing 36. The drive shaft 39 is connected to the main arm 37, and this rotation is transmitted to the main arm 37 when the drive shaft 39 rotates. An inner end portion of the main arm 37 is fixed to the drive shaft 39, and an outer end portion is engaged with the unison ring 45. Therefore, the main arm 37 rotates around the drive shaft 39, and this rotation is transmitted to the unison ring 45. The arm 44 is fitted on the inner peripheral surface of the unison ring 45, and when the unison ring 45 rotates, this rotation is transmitted to the arm 44. The arm 44 can rotate about the vane shaft 21, and the rotation of the arm 44 is transmitted to the vane shaft 21. Since the vane shaft 21 is connected to the nozzle vane 42, the nozzle vane 42 rotates together with the vane shaft 21 and the arm 44.

  The nozzle plate 43 is in contact with the turbine housing 48, and a link chamber 301 is provided between the turbine housing 48 and the center housing 36. The link chamber 301 is an internal space for storing the drive mechanism. The turbine housing 48 is provided with a turbine housing vortex chamber. Exhaust gas is supplied to the turbine housing vortex chamber, and the flow of the exhaust gas rotates the turbine wheel assembly 22. The rotation of the turbine wheel assembly 22 is transmitted to the compressor wheel 34 via the turbine shaft 7. Spacer bolts 47 are attached to the turbine housing 48.

  The drive link 41 of the drive mechanism 202 is connected to the motor rod 302. The motor rod 302 is a rod-like member and is connected to the link 33 and the variable nozzle controller 270. The variable nozzle controller 270 is connected to a direct current motor (DC motor). When the direct current motor rotates, the rotation is transmitted to the link 303 via the gear mechanism and the worm mechanism, and is driven from the link 303 via the motor rod 302. The link 41 is moved.

  The position of the link 303 is detected by an opening degree sensor 304, and the opening degree sensor 304 measures the position of the link 303. Thereby, the inclination angle of the nozzle vane 42 as the variable nozzle is detected.

  FIG. 4 is a schematic cross-sectional view for explaining the center housing in detail. Referring to FIG. 4, the center housing 36 of the floating bearing structure is provided with an internal space 6 for accommodating the turbine shaft 7. The interior space 6 is filled with oil 100. A floating bush 24 is disposed in the oil 100, and the floating bush 24 holds the turbine shaft 7. The center housing 36 is provided with a first oil supply path 136 and a second oil supply path 236. In this embodiment, the second oil supply path 236 is branched from the first oil supply path 136, but the present invention is not limited to this, and the first oil supply path 136 and the second oil supply path 236 are not limited thereto. And may be provided separately and independently.

  The turbocharger 1 includes a turbine shaft 7 as a shaft extending in one direction, a cylindrical floating bush 24 that surrounds the turbine shaft 7 and has an inner peripheral surface 224 that faces the outer peripheral surface 71 of the turbine shaft 7, and a floating bush And a center housing 36 in which an internal space 6 for storing 24 is provided. The floating bush 24 is provided with a through hole 124 that penetrates from the outer peripheral surface 324 to the inner peripheral surface 224. The center housing 36 is provided with a first oil supply path 136 that supplies oil to the through hole 126 and a second oil supply path 236 that supplies oil to the outer peripheral surface 324 of the floating bush 24. Three or more second oil supply paths 236 are provided for one floating bush 24. The three or more second oil supply paths 236 are arranged at a distance from each other in the circumferential direction of the outer peripheral surface.

  The floating bush 24 provided in the turbocharger 1 is driven by an oil film formed between the turbine shaft 7 and the floating bush 24 and follows the swing of the turbine shaft 7. Whirl vibration occurs when the turbine shaft 7 rotates. There are two modes of whirl vibration: a conical mode that occurs at low frequencies and a cylindrical mode that occurs at medium and high frequencies. In this embodiment, the second oil supply path 236 is provided from the second oil supply path 236 to the outer peripheral surface 324 of the floating bush 24 in order to effectively suppress the swing of the turbine shaft 7 due to the whirl vibration. Inject oil towards you. When the whirl vibration occurs, any part of the outer peripheral surface 325 approaches the second oil supply path 236. Since the strong oil is injected from the second oil supply path 236 to the approaching portion, the approaching portion tries to return to the original position. Thereby, whirl vibration can be suppressed. The turbine shaft 7 is moved by vibration to a position indicated by a dotted line in FIG. The turbine shaft 7 rotates in the direction indicated by the arrow R, and a second oil supply path 236 is provided in order to suppress whirl vibration during this rotation.

  FIG. 5 is a cross-sectional view taken along line VV in FIG. Referring to FIG. 5, oil 100 is stored in the internal space 6 of the center housing 36, and the floating bush 24 is disposed in the oil 100. Three second oil supply paths 236 are disposed so as to face the outer peripheral surface 324 of the floating bush 24. The number of second oil supply paths 236 is not limited to three, and more second oil supply paths 236 may be provided.

  The oil 100 supplied from the second oil supply path 236 is sprayed on the outer peripheral surface 324 of the floating bush 24. As a result, when the floating bush 24 vibrates and approaches the center housing 36, the floating bush 24 is returned to the vicinity of the center by the pressure of the oil supplied from the second oil supply path 236. Thereby, whirl vibration can be suppressed.

(Embodiment 2)
FIG. 6 is a sectional view of a turbocharger according to the second embodiment of the present invention. Referring to FIG. 6, in turbocharger 1 according to the second embodiment, the arrangement direction of second oil supply path 236 is different from the turbocharger according to the first embodiment. That is, the second oil supply path 236 is disposed so as to be inclined with respect to the radial direction indicated by the dotted line 261a in FIG. 6, and the inclination causes the first oil supply path 236 to be prevented from rotating in the rotational direction indicated by the arrow R. 2 Oil supply path 236 supplies oil. That is, oil is injected in the direction opposite to the rotation direction indicated by the arrow R.

  The turbocharger 1 according to the second embodiment configured as described above has the same effects as the first embodiment. Further, when the floating bush 24 approaches the second oil supply path 236, the oil flowing in the reverse direction is applied to the floating bush 24, so that the rotation of the floating bush 24 can be reduced. Thereby, generation | occurrence | production of a whirl vibration can be suppressed.

  Although the embodiment of the present invention has been described above, the embodiment shown here can be variously modified. First, the engine to which the turbocharger is attached may be either a diesel engine or a gasoline engine. Further, the rotation of the turbine shaft 7 may be assisted by a motor. Moreover, you may generate electric power with a motor using the rotational force of the turbine shaft 7. FIG.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram which shows the diesel engine system which has a turbocharger according to Embodiment 1 of this invention. 1 is a perspective view including a partial cross section of a turbocharger according to a first embodiment of the present invention. It is sectional drawing along the III-III line in FIG. It is typical sectional drawing for demonstrating a center housing in detail. It is sectional drawing along the VV line in FIG. It is sectional drawing of the turbocharger according to Embodiment 2 of this invention.

Explanation of symbols

  1 turbocharger, 7 turbine shaft, 24 floating bush, 36 housing, 124 through hole, 224 inner peripheral surface, 324 outer peripheral surface.

Claims (2)

A shaft extending in one direction;
A cylindrical floating bush surrounding the shaft and having an inner peripheral surface facing the outer peripheral surface of the shaft;
A housing provided with an internal space for storing the floating bush,
Oil is interposed between the outer peripheral surface of the shaft and the inner peripheral surface of the floating bush, and between the outer peripheral surface of the floating bush and the inner peripheral surface of the housing,
The floating bush is provided with a through-hole penetrating the floating bush in the radial direction from the outer peripheral surface to the inner peripheral surface,
The housing is provided with a first oil supply path for supplying oil to the through-hole and three or more second oil supply paths for injecting oil toward the outer peripheral surface of the floating bush. The above-described second oil supply path is a floating bearing structure, which is disposed at a distance from each other in the circumferential direction of the outer peripheral surface.   The floating bearing structure according to claim 1, wherein the second oil supply path injects oil toward the floating bush in a direction that prevents rotation of the floating bush.

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