JP2010138896A - Vibration reduction in turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid disadvantages such as encroachment on a usable rotational frequency region, degradation of efficiency, noise, an increase in load to a material, and functional disorder of a structure in the case resonance occurs, occurring by vibration of turbine blades. <P>SOLUTION: A fluid mechanism for the turbocharger having a guide device including a housing (1) defining a flow passage of a fluid flowing through the fluid mechanism, an impeller hub (2) rotatably supported in the housing (1), a plurality of turbine blades (3) provided to the hub (2) for changing the flow direction of the fluid, and guide blades (4) for changing the flow direction of the fluid, and an interference generating device (5) for generating interference in the flow of the fluid is proposed. The interference reduces vibration of the turbine blades (3) caused by the guide blades (4) by superposition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The invention relates to a fluid mechanism for a turbocharger as claimed in claim 1, a turbocharger for such a self-igniting internal combustion engine comprising such a fluid mechanism, and such a turbocharger. And a method for reducing vibration.

  A turbocharger for an internal combustion engine always has two fluid mechanisms: a compressor for compressing the combustion air for the internal combustion engine and a turbine for driving the compressor. In particular, in a turbocharger for a self-igniting internal combustion engine having a high output, for example a marine diesel engine, the compressor and the turbine are mechanical and thermodynamic by the fluid flowing through the compressor and the turbine, ie combustion air or exhaust gas. High load. On the other hand, efforts are now being made to mount such turbine blades of a fluid mechanism as slim as possible.

  However, such a moving blade is particularly susceptible to vibration excitation because of its small moment of inertia and rigidity. Such vibrations are induced, inter alia, by the guide vanes of the inflow guide device or the outflow guide device upstream or downstream of the turbine blade, causing the guide blade to cause interference, which is often periodic, in the fluid flow. Is done. The fluid thus interfering then vibrates turbine blades, which today tend to form increasingly thin. Such vibrational excitation violates the available speed range, reduces efficiency, increases noise and material loading, and can lead to structural failure in the event of resonance. There is sex.

  Therefore, the problem to be solved by the present invention is to reduce or avoid one or more of the above mentioned damages.

  In order to solve the above-mentioned problem, the fluid mechanism described in the writing portion in claim 1 is further formed by the features described in the claim. Claim 11 claims protection for a turbocharger with such a fluid mechanism, and claim 12 claims protection for a method for reducing vibrations in such a turbocharger. Advantageous embodiments and further formations of the invention are described in the dependent claims.

  As is well known, a fluid mechanism of a turbocharger according to the present invention includes a housing that defines a flow path for fluid flowing through the fluid mechanism, an impeller hub that is rotatably supported in the housing, and a fluid. A plurality of turbine rotor blades provided in the hub for changing the direction of the flow of the fluid, and a guide device including a guide blade for changing the direction of the flow of the fluid.

  The fluid flow is, for example, fuel air for an internal combustion engine, in particular fuel air compressed by a turbocharger compressor formed as a centrifugal compressor or a mixed flow compressor, or exhaust gas of an internal combustion engine, in particular a shaft. It may be exhaust gas that drives a turbine of a turbocharger formed as a flow turbine.

  The guide device may be an outflow guide device that is downstream in the flow direction and placed downstream of the turbine blade, but is also an inflow guide device that is upstream in the flow direction and forward of the turbine blade. obtain. The guide wing may be fixed relative to the guide device or may be adjustable.

  Such guide devices cause flow interference in the fluid, in particular pressure or velocity fluctuations, such as parasitic flow or opposing flow, which can cause the blades to vibrate.

  Therefore, it is proposed by the present invention that interference is generated in the fluid flow by the interference generator, which reduces the vibration of the turbine blades caused by the guide blades by superposition.

  It is known that the vibration amplitude can be reduced or eliminated by superposition of vibrations having substantially opposite phases. This principle, known as the principle of interference or counter-noise or anti-noise principle, can preferably be used in two ways in the present invention. That is, on the other hand, the interference generating device can cause flow interference, particularly pressure or velocity fluctuations in the fluid, which flow interference, especially pressure or velocity fluctuations cause the blades to vibrate, which are then superimposed. Reduces vibrations caused by the guide vanes. In this way, the turbine blades are interfered with two flows, and the vibrations of the turbine blades reduce each other due to the interference of the two flows. Additionally or alternatively, the interference generator can also cause flow interference in the fluid, in particular pressure or velocity fluctuations, which flow interference, in particular pressure or velocity fluctuations, are caused by the guide wings by superposition. And reducing flow interference that excites unwanted vibrations in the blades. The flow interference caused to the turbine blade and thus the excitation of vibrations in the turbine blade are thus reduced.

  In particular, resonant vibrations in turbine blades can be reduced or avoided in this way. The method allows the use of rotational speed regions that would otherwise be inaccessible due to resonant vibrations, increase efficiency, improve thermodynamic and / or mechanical parameters, and / or increase noise or The load on the material can be significantly reduced.

  The interference generator may be formed as an active member, such as a piezoelectric sensor, an electromagnetically actuable membrane, etc., to cause a suitable flow interference in the fluid. Additionally or alternatively, the interference generator has one or more geometric discontinuities. As fluid flows along such discontinuities, the flow is interfered.

  The position and / or shape of the geometric discontinuity is preferably selected such that the vibration of the turbine blade caused by the guide blades is reduced by superposition. The person skilled in the art can determine the optimum discontinuities for the current fluid mechanism, for example by experimental and / or simulation calculations, in particular vibrations and / or flow simulations by the finite element method.

  One or more of the discontinuities can be formed in the wall, in particular as a recess or outlet without a penetration, i.e. as a sac-like recess, through which the fluid passes. Such a recess can be easily manufactured with a suitable shape. Additionally or alternatively, the discontinuity can be formed in the wall as a ridge, through which fluid passes. Such recesses and / or ridges can be formed from the original with the wall, or can be formed later, such as by cutting or applying additional material.

  Such recesses and / or ridges may have, for example, a circular, elliptical, drop-shaped, or rectangular cross-section where the fluid circulates. The recess may for example be formed in the shape of a hole, in particular a long hole or a slit. The main axis of the cross section of the recess or ridge through which the fluid circulates may extend in the axial direction and / or circumferential direction.

  The interference generating device, in particular said discontinuity, can preferably be provided in the guide device and / or in a housing that defines a flow path for the fluid.

  The number of geometric discontinuities preferably corresponds to the number of guide vanes of the guide device or an integer multiple of the number of guide vanes. This is because interference particularly suitable for reducing the vibration caused by the guide vanes is caused in the fluid flow.

  For particularly effective vibration reduction, the phase of the vibration caused to the turbine blade by the interference generator or the phase of the interference caused to the fluid flow by the interference generator is different from the phase of the vibration or interference caused by the guide blade. On the other hand, it may be oriented in approximately the opposite direction. However, vibrations or interference with other phase shifts and / or other frequencies are also suitable to reduce the vibrations caused by the guide vanes.

  Further advantages and features are described in the dependent claims and in the embodiments. The parts are schematically shown in the following drawings with respect to the embodiments.

It is a fragmentary perspective view of the compressor of the turbocharger by the Example of this invention. 1 is a partial perspective view of a turbine of a turbocharger according to an embodiment of the present invention.

  FIG. 1 is a perspective view showing a part of a centrifugal compressor of a turbocharger of a marine diesel engine according to the present invention.

  The impeller hub or rotor hub 2 is supported in the housing 1, whereby a flow path for combustion air for a marine diesel engine is defined between the impeller hub and the housing. A turbine rotor blade 3 for accelerating air is provided in the flow path, and the turbine rotor blade rotates around the longitudinal axis of the compressor at the rotation speed n together with the impeller hub 2 and is provided downstream. Air is conveyed to the guide vanes 4 of the outflow guide device, where the kinetic energy of the air is partially converted into pressure energy.

  The guide vanes 4 cause interference in the air flow in the form of pressure and velocity fluctuations, which are brought to the turbine blade 3. Turbine blades are formed with a small wall thickness and thereby have a low bending strength, so that interference of air flow caused by the guide blades 4 causes undesirable vibrations in the turbine blades.

  In the housing 1, long holes 5 are formed upstream of the individual guide blades 4, and the long holes extend substantially in the circumferential direction. This also causes interference in the air flow in the form of pressure and velocity fluctuations, which also cause the turbine blade 3 to vibrate. The position, shape, size and depth of the long hole 5 are selected as follows. That is, the vibration caused to the turbine rotor blade by the long hole is selected so as to have a phase substantially opposite to the vibration caused by the guide blade 4. Accordingly, the two vibrations in the turbine rotor blade 3 are substantially eliminated from each other by the superposition, whereby the overall vibration amplitude of the turbine rotor blade 3 is greatly reduced.

  FIG. 2 is a perspective view showing a part of an axial flow turbine of a turbocharger of a marine diesel engine according to the present invention. Corresponding members are indicated by the same reference numerals as in FIG.

  Corresponding to FIG. 1, the impeller hub 2 is supported in the housing 1, thereby defining a flow path for the exhaust gas of the marine diesel engine between the impeller hub and the housing. A turbine rotor blade 3 for changing the direction of the exhaust gas is provided in the flow path, and the turbine rotor blade rotates around the longitudinal axis of the turbine at the rotation speed n together with the impeller hub 2.

  The guide blades 4 of the guide device that redirect the exhaust gas in a suitable manner cause interference in the air flow in the form of pressure and velocity fluctuations, which interference is brought to the turbine blade 3. The turbine blades are formed with a small wall thickness and thereby have a low bending strength, so that the turbine blades undergo undesirable vibrations due to exhaust gas interference caused by the guide blades 4.

  A long hole 5 formed in the housing 1 is provided for each guide blade 4, and the long hole extends substantially in the circumferential direction. This also causes interference in the exhaust gas flow in the form of pressure and velocity fluctuations. The position, shape, size and depth of the long hole 5 are selected as follows. In other words, the interference caused to the exhaust gas flow by the long holes is selected so as to have a phase substantially opposite to the interference caused by the guide vanes 4. Accordingly, the two interferences in the exhaust gas flow are almost eliminated from each other by superposition, thereby reducing the load on the turbine blade 3 and reducing the generation of vibrations. In this case as well, the overall vibration amplitude of the turbine blade 3 is greatly increased. Reduced.

DESCRIPTION OF SYMBOLS 1 Housing 2 Impeller hub 3 Turbine rotor blade 4 Guide blade 5 Hole n Rotation speed

Claims (13)

A fluid mechanism for a turbocharger,
A housing (1) defining a flow path for fluid flowing through the fluid mechanism;
An impeller hub (2) rotatably supported in the housing;
A plurality of turbine blades (3) provided in the hub for redirecting the flow of fluid;
In a fluid mechanism comprising a guide device comprising a guide blade (4) for changing the direction of flow of the fluid,
An interference generating device (5) for generating interference in the fluid flow is provided, and the interference reduces the vibration of the turbine rotor blade (3) caused by the guide blade (4) by superposition. A fluid mechanism characterized by.   2. Fluid mechanism according to claim 1, characterized in that the fluid mechanism is a turbocharger compressor, in particular a centrifugal or mixed flow compressor, or a turbine, in particular an axial turbine.   The guide device is an outflow guide device downstream in the flow direction and placed downstream of the turbine blade (3), or an inflow guide upstream of the flow direction and forward of the turbine blade (3). The fluid mechanism according to claim 1, wherein the fluid mechanism is an apparatus.   The interference generating device is formed to generate interference in the flow of fluid flowing through the fluid mechanism, thereby generating vibration in the turbine rotor blade (3) via the fluid, The vibration of the turbine blade (3) caused by the guide blade (4) is reduced by superposition and / or the interference caused by the flow of fluid flowing through the fluid mechanism by the guide blade (4) is superimposed. The fluid mechanism according to any one of claims 1 to 3, wherein the fluid mechanism is reduced by combination.   5. Fluid mechanism according to any one of the preceding claims, characterized in that the interference generating device has at least one geometrical discontinuity (5).   6. Fluid mechanism according to claim 5, characterized in that the at least one discontinuity is formed as a through-hole or a recess (5) without an outlet or as a ridge.   7. Fluid mechanism according to claim 6, characterized in that at least one discontinuity (5) has a cross section through which the fluid circulates, the main axis of the cross section extending in the axial direction and / or the circumferential direction.   The fluid mechanism according to any one of claims 1 to 7, wherein the interference generating device is provided in the guide device and / or the housing (1).   8. The number of geometric discontinuities corresponds to the number of the guide vanes (4) of the guide device or an integer multiple of the number of the guide vanes. 9. The fluid mechanism described in 1.   The position and / or shape of the geometric discontinuity is selected such that the resonance amplitude of the vibration of the turbine blade (3) caused by the guide blade (4) is reduced by superposition The fluid mechanism according to any one of claims 5 to 9, wherein:   The phase of vibration caused to the turbine blade (3) by the interference generator (5) is oriented in a substantially opposite direction to the phase of vibration caused by the guide blade (4), and / or The phase of interference caused by the fluid flow by the interference generator (5) is oriented in a substantially opposite direction to the phase of interference caused by the guide vanes (4). The fluid mechanism according to any one of 1 to 10.   A turbocharger, in particular for a self-igniting internal combustion engine, comprising a fluid mechanism according to any one of the preceding claims.   12. A method for reducing vibrations caused by said guide blades (4) in said turbine blade (3) of a turbocharger fluid mechanism according to claim 11, wherein said interference generator (5) Interfering with the flow, said interference reducing the vibration of the turbine blade (3) caused by the guide blade (4) by superposition.

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