U.S. patent application number 10/489663 was filed with the patent office on 2004-12-02 for turbocharger comprising a torsional-vibration damper.
Invention is credited to Loos, Markus.
Application Number | 20040241015 10/489663 |
Document ID | / |
Family ID | 8184140 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040241015 |
Kind Code |
A1 |
Loos, Markus |
December 2, 2004 |
Turbocharger comprising a torsional-vibration damper
Abstract
The invention relates to an exhaust-gas turbocharger, which is
operated by the exhaust gas of a combustion engine and is equipped
with a rotor unit that rotates at high-speed. Said rotor unit
comprises a turbocharger shaft, a turbine wheel that is
rotationally fixed to the shaft, in addition to a compressor wheel
that is rotationally fixed to the shaft. To increase the
operational reliability of said turbocharger, a torsional-vibration
damper is located on the turbocharger shaft. The
torsional-vibration damper reduces torsional-vibration stresses
that arise in the shaft, which are caused by motor pulsations of a
higher order of the combustion engine.
Inventors: |
Loos, Markus; (Baden,
CH) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
8184140 |
Appl. No.: |
10/489663 |
Filed: |
March 16, 2004 |
PCT Filed: |
September 13, 2002 |
PCT NO: |
PCT/CH02/00506 |
Current U.S.
Class: |
417/407 |
Current CPC
Class: |
F01D 25/04 20130101;
F04D 25/04 20130101; F04D 29/668 20130101; F05D 2220/40 20130101;
F05D 2260/96 20130101; F01D 5/027 20130101; F02C 6/12 20130101 |
Class at
Publication: |
417/407 |
International
Class: |
F04B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 2001 |
EP |
01810898.5 |
Claims
1. An exhaust gas turbocharger with a rapidly rotating rotor unit
which comprises a turbocharger shaft, a turbine wheel connected
fixedly in terms of rotation to the shaft, and a compressor wheel
connected fixedly in terms of rotation to the shaft, the exhaust
gas turbocharger being capable of being connected to an internal
combustion engine and the rotor unit being capable of being
operated by means of the exhaust gases from the internal combustion
engine, wherein the exhaust gas turbocharger comprises means for
the damping of torsional vibrations of the turbocharger shaft which
are excited by higher engine orders of the internal combustion
engine when the exhaust gas turbocharger is in the state connected
to the internal combustion engine, the damping means comprising, a
torsional vibration damper arranged on the shaft.
2. The turbocharger as claimed in claim 1, wherein the torsional
vibration damper is a viscose torsional vibration damper.
3. The turbocharger as claimed in claim 1, wherein the torsional
vibration damper is an oil displacement damper.
4. The turbocharger as claimed in claim 1, wherein the torsional
vibration damper is a rubber damper.
5. The turbocharger as claimed in claim 1, wherein the torsional
vibration damper is a silicone-oil rubber damper.
6. The turbocharger as claimed in claim 1, wherein the torsional
vibration damper is secured to the turbocharger shaft in the region
of the compressor, and, in particular, on the inlet side upstream
of a compressor hub of the compressor wheel.
7. The turbocharger as claimed in claim 6, wherein the outside
diameter of the torsional vibration damper is about 80% to 110%,
preferably 90% to 100%, of the outside diameter of the compressor
hub in that region of the compressor hub which follows the
device.
8. The turbocharger as claimed in claim 1, wherein the torsional
vibration damper is arranged between the compressor wheel and the
turbine wheel or in the region of the turbine.
9. The turbocharger as claimed in claim 1, wherein more than one
torsional vibration damper is arranged on the turbocharger shaft,
in which case the torsional vibration dampers may be arranged at
various locations on the shaft and various types of torsional
vibration dampers may be provided.
Description
TECHNICAL FIELD
[0001] The invention relates to a turbocharger according to the
features of the preamble of patent claim 1.
PRIOR ART
[0002] Turbo chargers are used for increasing the power of
reciprocating piston engines. They possess a rapidly rotating rotor
unit which comprises a turbine, a compressor and a shaft connecting
the turbine and compressor. In exhaust gas turbochargers, the
turbine of the turbocharger is operated by means of the exhaust gas
from an internal combustion engine. The turbine drives the
compressor by means of the common shaft. The gas compressed by the
compressor is supplied to the combustion chambers of the engine for
charging the latter. The pressure, acting upon the turbine, of the
exhaust gas from the internal combustion engine is not constant,
and this may excite the turbocharger shaft into vibrations. The
pressure pulsations depend, inter alia, on the opening and closing
characteristic of the outlet valves of the engine and on the
configuration of the exhaust line. The predominating ignition
frequency of the engine is clearly to the forefront in the
frequency spectrum of these pressure pulsations, said ignition
frequency depending on the number of cylinders, on the working
process (2-stroke/4-stroke) and on the engine rotational speed. It
is the state of the art to dimension the shaft of the turbocharger
in such a way that all the characteristic torsional frequencies of
the turbocharger shaft are well above the maximum possible ignition
frequency of the engine. It has thereby been possible hitherto to
avoid resonance between the main excitation and the characteristic
torsional frequencies and to design the turbochargers so as to be
operationally reliable.
[0003] More recent investigations and measurements have shown that
higher engine orders also occur in the pressure pulsation spectrum
in addition to the ignition frequency. These pressure pulsations of
higher order may coincide with the characteristic torsional
frequency of the turbocharger shaft. These resonant vibrations,
which cannot be avoided in the case of variable engine rotational
speed, lead to torsional stresses in the turbocharger shaft. In the
past, however, the level of excitation was so low that, owing to
the internal damping of the turbocharger shaft, the resonant
vibrations led only to insignificant torsional stresses which were
tolerable over the long term.
[0004] However, due to steeper camshaft flanks and also rising
pressure conditions in engines and turbochargers, higher
excitations and consequently higher torsional stresses in the
turbocharger shaft are to be expected. The required increasing
power density of the turbocharger shaft is a further factor which
aggravates the problem. Inadmissibly high loads on the turbocharger
shaft are therefore to be expected in future.
[0005] The only measure known hitherto for counteracting the loads
caused by torsional vibrations in the turbomachines themselves is
the selection of larger shaft diameters. However, this is
associated with higher power losses in the shaft bearings of the
turbocharger.
PRESENTATION OF THE INVENTION
[0006] The object of the invention is, therefore, to provide a
cost-effective turbocharger with a rapidly rotating rotor unit, the
operating reliability of which is ensured without efficiency
losses, even in the event of the rising levels of excitation to be
expected in future for torsional vibrations of the turbocharger
shaft.
[0007] This object is achieved by means of a turbocharger according
to the features of patent claim 1. The arrangement of a torsional
vibration damper on the turbocharger shaft reduces the load on the
turbocharger shaft caused by any occurring torsional vibrations and
thus prevents critical load peaks. Operating reliability is thus
ensured even in the case of configurations with steep camshaft
flanks and/or rising pressure conditions in the engine and
turbocharger.
[0008] The known principles of torsional vibration dampers, such as
oil displacement dampers, rubber dampers, viscose torsional
vibration dampers and silicone-oil rubber dampers, come into
consideration. Such dampers known per se are described, for
example, in "Berechnung des dynamischen Verhaltens von
Viskosedrehschwingungs-dmpfern", ["Calculation of the dynamic
behavior of viscose torsional vibration dampers"], Dissertation TU
Berlin, 1982, Dipl. Ing. Rainer Hartmann, pp. 9-13.
[0009] The dampers are advantageously arranged at the
compressor-side shaft end, in particular on the inlet side of the
compressor wheel hub, since the vibration deflections and
consequently the damping action are at their greatest there. A
further advantage is also the good cooling action in the case of a
relatively constant and low temperature, this being advantageous
for all forms of damper construction.
[0010] In an arrangement at the inlet of the compressor wheel, the
outside diameter of the torsional vibration damper is selected such
that it corresponds to approximately 80%-110%, most preferably to
90% to 100%, of the hub diameter of the compressor at the inlet. As
a result, the radial construction space is utilized efficiently and
the inflow of the compressor is not disturbed.
[0011] It may also be envisaged to arrange the damper in the region
of the turbine, in which case it is necessary to ensure that
materials with sufficient heat resistance are used.
[0012] It is likewise advantageous to arrange the torsional
vibration damper between the turbine wheel and the compressor
wheel. Since the construction space which is present there is
larger, above all, in the radial direction, the dimensioning of the
damper is simpler.
[0013] The use of a viscose torsional vibration damper has proved
particularly advantageous. An annular rotary mass is mounted freely
rotatably on the inside in a housing. A viscous medium is
introduced in the gap between ring and housing and, in the event of
relative movements between the two parts, generates a damping
action as a result of the shearing forces which arise. In this
case, it is particularly important to stabilize the damper
temperature. The damper is therefore advantageously arranged at the
inlet of the compressor wheel. The air stream with very high flow
velocities in the inlet region of the compressor ensures an optimum
cooling of the damper and consequently a largely uniform
temperature of the damper.
[0014] Depending on the design of the turbocharger and on the
torsional vibration loads which occur, it may be advantageous to
arrange a plurality of torsional vibration dampers on the
turbocharger shaft instead of one torsional vibration damper. In
this case, identical or different torsional vibration dampers may
be used in accordance with the load, and they may be provided
directly next to one another or at various locations on the
shaft.
[0015] Further preferred embodiments are the subject matter of
further dependent patent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The subject of the invention is explained in more detail
below with reference to preferred exemplary embodiments illustrated
in the accompanying purely diagrammatic drawings, in which:
[0017] FIG. 1 shows, in a section along its longitudinal axis, a
turbocharger with a torsional vibration damper in the region of,
the compressor inlet;
[0018] FIG. 2 shows the turbocharger from FIG. 1 with a torsional
vibration damper in the region between the compressor wheel and
turbine wheel;
[0019] FIG. 3 shows the result of a measurement of the amplitude of
the torsional vibration on a turbocharger shaft with torsional
vibration damper; and
[0020] FIG. 4 shows the result of a measurement of the amplitude of
the torsional vibration on a turbocharger shaft with torsional
vibration damper.
[0021] The reference symbols used in the drawings and their
significance are collated in the list of reference symbols.
Basically, identical parts are given the same reference symbols in
the figures. The embodiment described stands as an example of the
subject of the invention and has no restrictive effect.
WAYS OF CARRYING OUT THE INVENTION
[0022] FIGS. 1 and 2 each show a turbocharger 10 with a rapidly
rotating rotor unit 11 in a section along their longitudinal axes
18. Each rapidly rotating rotor unit 11 comprises a turbine 12 and
a compressor 16 which are connected to one another via a common,
turbocharger shaft 14. The turbine 12 has a turbine wheel 22,
surrounded by a turbine housing 20 and having turbine blades 23.
The compressor wheel 26 has compressor blades 27 which are
distributed regularly over the circumference of a compressor wheel
hub 25. The compressor wheel 26 is surrounded by a compressor
housing 24 and can be driven by the turbine 12 by means of the
common shaft 14. The common turbocharger shaft 14 is mounted
between the compressor wheel 26 and the turbine wheel 22 in a
bearing housing 28.
[0023] The turbine housing 20 forms a flow duct 29 which is
connected (not illustrated) to the exhaust line of an internal
combustion engine. The flow duct 29 leads via the turbine wheel 22
and makes it possible, via a gas outlet housing 30 of the turbine
housing 20, to discharge the exhaust gas of the internal combustion
engine from the turbocharger 10. The compressor housing forms a
second flow duct 32, via the inlet 34 of which air or another
combustible gas is sucked in, led via the compressor wheel 26 and
at the same time compressed. The compressed gas is finally
discharged from the turbocharger 10 via an outlet, not explicitly
illustrated, of the compressor housing 24 and into a feed line of
the internal combustion engine (not illustrated).
[0024] The pressure pulses which are transmitted to the
turbocharger shaft 14 by the exhaust gas of the internal combustion
engine according to its engine order when said exhaust gas flows
over the turbine wheel 26 are damped by means of a torsional
vibration damper 36. In the example shown here, this is a viscose
torsional vibration damper which is secured fixedly in terms of
rotation to the shaft 14 on the inlet side upstream of a compressor
hub 25 of the compressor wheel 26. By virtue of this positioning,
it is possible for the viscose torsional vibration damper to be
cooled optimally by the gas flowing in. Moreover, the torsional
vibration damper is thus located in the region of the highest
torsional vibration amplitudes of the shaft 14 and can therefore
exert its greatest action. In this example, the radial extent of
the torsional vibration damper 36 amounts to 100% of the radial
extent of the compressor wheel hub 25 in the region of the latter
which follows the torsional vibration damper 36. The construction
space is thereby utilized optimally, without the flow via the
compressor wheel 26 being impeded.
[0025] The turbocharger 10 in FIG. 2 is identical to the
turbocharger 10 from FIG. 1. The torsional vibration damper 36 for
reducing the torsional vibration load on the shaft 14, however, is
not connected fixedly in terms of rotation to the turbocharger
shaft 14 in the region of the compressor wheel 26, but, instead,
between the compressor wheel 26 and turbine wheel 22 in the region
of the bearing housing 28 of the turbocharger 10. The greater
radial construction space can advantageously be utilized here, thus
giving the torsional vibration damper 36 a higher efficiency. This
higher efficiency, admittedly, cannot always have a full effect on
dampening efficiency because of the greater proximity to the nodal
point of the torsional vibration. Owing to the poorer cooling
possibilities, a rubber damper is used here instead of a viscose
torsional vibration damper.
[0026] FIGS. 3 and 4 show, by way of example, results of two
measurements of the torsional vibration amplitudes on a
turbocharger shaft, on the one hand, without a torsional vibration
damper in FIG. 3, and, on the other hand, with a torsional
vibration damper in FIG. 4. The measurements are based on the use
of a viscose torsional vibration damper in the region of the inlet
of the compressor. The vibration frequency of the torsional
vibration is plotted at the top in Hertz and the rotational speed
is plotted on the right in revolutions per second. The engine
orders 40 which occur are plotted diagonally. The increased
amplitudes 42 of the torsional vibrations 44 in the region of the
associated exciting engine order 40 can be seen clearly in both
figures. However, the level of the amplitudes 42 in FIG. 4,
measured on the turbocharger shaft with a torsional vibration
damper, is substantially lower than in FIG. 3, measured on the
turbocharger shaft without a torsional vibration damper. These
results show that the use of torsional vibration dampers in
turbochargers can contribute considerably to the operating
reliability of the turbochargers.
List of Reference Symbols
[0027] 10 Turbocharger
[0028] 12 Turbine
[0029] 14 Shaft
[0030] 16 Compressor
[0031] 18 Longitudinal axis
[0032] 20 Turbine housing
[0033] 22 Turbine wheel
[0034] 23 Turbine blades
[0035] 24 Compressor housing
[0036] 25 Compressor-wheel hub
[0037] 26 Compressor wheel
[0038] 27 Compressor blades
[0039] 28 Flow duct
[0040] 30 Gas outlet housing
[0041] 32 Flow duct
[0042] 34 Inlet
[0043] 36 Torsional vibration damper
[0044] 40 Engine order
[0045] 42 Torsional vibration amplitude
[0046] 44 Torsional vibration
* * * * *