U.S. patent application number 13/121705 was filed with the patent office on 2011-09-15 for support plate for bearings.
This patent application is currently assigned to ROBERT BOSCH GMBH. Invention is credited to Stefan Einbock, Vincent Riou, Ruediger Schroth.
Application Number | 20110220769 13/121705 |
Document ID | / |
Family ID | 41172361 |
Filed Date | 2011-09-15 |
United States Patent
Application |
20110220769 |
Kind Code |
A1 |
Einbock; Stefan ; et
al. |
September 15, 2011 |
SUPPORT PLATE FOR BEARINGS
Abstract
The invention relates to a support device (60) for fixing a
bearing (28) on a bearing shield (13.1, 13.2) of a housing (13) of
an electric machine (10). Rotatably mounted in the support device
is a rotor (20) with a shaft (27). The support device (60) is
substantially flat and comprises a plurality of fastening openings
(62) that are grouped about a central opening (64). The support
device (60) comprises at least one design break point (66, 68; 72,
74; 76, 78; 92) that acts to provide a local limit to the excess
stresses in the material of the support device (60).
Inventors: |
Einbock; Stefan; (Stuttgart,
DE) ; Riou; Vincent; (Ludwigsburg, DE) ;
Schroth; Ruediger; (Renningen-Malmsheim, DE) |
Assignee: |
ROBERT BOSCH GMBH
Stuttgart
DE
|
Family ID: |
41172361 |
Appl. No.: |
13/121705 |
Filed: |
September 28, 2009 |
PCT Filed: |
September 28, 2009 |
PCT NO: |
PCT/EP2009/062516 |
371 Date: |
May 10, 2011 |
Current U.S.
Class: |
248/224.8 |
Current CPC
Class: |
F16C 35/067 20130101;
F16C 2380/26 20130101; F16C 35/00 20130101; H02K 5/1732 20130101;
F16C 33/76 20130101; F16C 2226/60 20130101; F16C 19/06 20130101;
Y10T 29/49947 20150115; F16C 19/522 20130101; F16C 19/54
20130101 |
Class at
Publication: |
248/224.8 |
International
Class: |
F16C 41/00 20060101
F16C041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 2, 2008 |
DE |
102008042552.4 |
Claims
1. A support device (60) for fixing a bearing (28) on a bearing
plate (13.1, 13.2) of a housing (13) of an electric machine (10),
in which a rotor (20) is rotatably mounted with a shaft (27), and
the support device (60) is of substantially plate-shaped
configuration and has a number of fastening openings (62) which are
arranged around an opening (64), characterized in that the support
device (60) has at least one predetermined break point (66, 68; 72,
74; 76, 78; 92) which brings about locally delimited excessive
loadings.
2. The support device (60) as claimed in claim 1, characterized in
that at least one predetermined break point (66, 68; 72, 74) is
configured as a notch.
3. The support device (60) as claimed in claim 1, characterized in
that at least one predetermined break point (76, 78) is configured
as an aperture in the material of the support device (60).
4. The support device (60) as claimed in claim 2, characterized in
that at least one predetermined break point (92) is configured as a
notch on a planar side (94, 96) of the support device (60).
5. The support device (60) as claimed in claim 2, characterized in
that at least one predetermined break point (66, 68; 72, 74) is
configured on an external circumference of the support device
(60).
6. The support device (60) as claimed in claim 2, characterized in
that a number of predetermined break points (66, 68; 72, 74) are
configured on at least one of an external circumference and an
internal diameter (80) of the central opening (64).
7. The support device (60) as claimed in claim 2, characterized in
that the support device is configured with a variable thickness
(82, 84).
8. The support device (60) as claimed in claim 7, characterized in
that the support device has a tapered section (84), in which
plastically deformable webs (86) extend.
9. The support device (60) as claimed in claim 2, characterized in
that at least one predetermined break point (66, 68; 72, 74; 92)
which is configured as a notch has a stress concentration factor of
K.sub.t>2.0.
10. The support device (60) as claimed in claim 6, characterized in
that at least two predetermined break points (66, 68; 72, 74) are
arranged so as to lie opposite one another on at least one of the
external circumference and the internal diameter (80) of the
central opening (64).
11. The support device (60) as claimed in claim 6, characterized in
that at least two predetermined break points (66, 68; 72, 74) lie
on the external circumference of the support device (60), one at
the 6 o'clock position and one at the 12 o'clock position, or on
the external circumference, one at the 3 o'clock position and one
at the 9 o'clock position.
12. The support device (60) as claimed in claim 11, characterized
in that at least two predetermined break points (66, 68; 72, 74)
lie on the internal diameter (80) of the central opening (64), one
at the 6 o'clock position and one at the 12 o'clock position, or on
the internal diameter (80) of the central opening (64), one at the
3 o'clock position and one at the 9 o'clock position.
13. The support device (60) as claimed in claim 6, characterized in
that at least two predetermined break points (66, 68; 72, 74) lie
on the internal diameter (80) of the central opening (64), one at
the 6 o'clock position and one at the 12 o'clock position, or on
the internal diameter (80) of the central opening (64), one at the
3 o'clock position and one at the 9 o'clock position.
Description
BACKGROUND OF THE INVENTION
[0001] As a rule, air-cooled generators for applications in the
automotive sector are mounted by means of a locating bearing in a
first bearing plate (A bearing plate) and a floating bearing in a
second bearing plate (B bearing plate). A ball bearing which is
used as a bearing is fixed axially here between a bearing plate and
a support plate. As a result of the generally present bearing play,
oscillations of the rotor occur as overall body in the axial
direction. This phenomenon which is also called rotor bouncing
occurs as a rule between 100 Hz and 500 Hz and is generally
associated with very high mechanical loadings in the generator on
various components.
[0002] DE 44 03 957 A1 relates to a flange bearing. Said flange
bearing serves to receive a prong shaft of the winch or the pick-up
drum of a harvester or of another correspondingly equipped
agricultural machine. The flange bearing comprises a bearing body
which is divided on one side and the outer casing of which has a
cylindrical center section. The latter is adjoined by sections
which are beveled conically on both sides. The bearing body is
provided with a web which permits positionally accurate insertion
of the bearings into the receptacle of a winch star and at the same
time serves as antirotation safeguard. The bearing halves are
connected elastically to one another by an integral hinge, a cutout
being provided in an adjacent manner to the integral hinge, which
cutout facilitates the widening of the bearing body, which is
produced from a robust plastic, during mounting and dismantling.
This solution concerns a hinge which can be bent more easily on
account of the lower rigidity at a notched point.
[0003] U.S. Pat. No. 3,431,032 discloses a cylindrical bearing
housing which has a milled slot as viewed in the axial direction.
As a result, internal stresses which are produced are dissipated,
such as residual stresses which are produced during casting.
Deformation of the bearing housing is possible as a result of the
slot.
[0004] DE 10 2004 053 078 A1 relates to a bearing arrangement. The
latter comprises a bearing carrier which is connected to a bearing
which is preferably configured as an antifriction bearing. In one
of its bearing rings, the bearing has a groove which extends in the
circumferential direction. At least one projection which is
arranged on the bearing carrier and extends in the radial direction
engages into said groove. At a circumferential point, the bearing
carrier has a slot which extends substantially in the radial
direction.
[0005] Finally, WO 03/081750 A1 discloses a generator for a
vehicle, the generator comprising a support plate which has a slot
which extends in the radial direction. Said slot which extends in
the radial direction serves as tolerance compensation means.
According to this solution, any stresses which possibly occur
during the screwing connection of the support plate are dissipated,
since a deformation of the material of the support plate is
possible as a result of the slot and accordingly a dissipation of
the stresses can take place.
SUMMARY OF THE INVENTION
[0006] The present invention is based on the object of protecting
the components of the generator from excessive mechanical loadings,
in particular excessively high oscillating accelerations, acting on
the components of the generator for too long.
[0007] Following the solution which is proposed according to the
invention, in an electric machine, for instance a generator which
is used in the automotive sector, the support plate is configured
in the region of the mounting in such a way that its macroscopic
geometry changes during the operation of the generator. In
particular, the change in the macroscopic geometry of the support
plate is manifested by visible plastic deformations up to and
including fractures of the support plate. The change in the
geometry of the support plate achieves a situation where mechanical
component loadings in the frequency range, for example, between 100
Hz and 500 Hz act for only a short time period on the components of
the electric machine, for instance of a generator and for the most
part are absorbed by the material of the support plate. To this
extent, the material of the support plate acts as an absorber or
damper, in particular for high mechanical oscillating
accelerations.
[0008] The change in the macroscopic geometry of the support plate
is achieved by the induced enforcement of fractures in the case of
excessive loads as a result of defined predetermined break points.
To this end, notches can be made at defined points of the support
plate, which notches lead to high but locally delimited excessive
loadings of the material of the support plate. If said delimited
excessive loadings exceed a limiting value, this necessarily leads
to the occurrence of a plastic deformation and, as a final
consequence, to the formation of fractures. As a result of the
support plates being partially or completely fractured at one or
more points, the transmission of high mechanical component loadings
to the components of the generator is avoided and damped or
absorbed by the partially/completely fractured support plate.
[0009] In addition to the formation of notches at defined points of
the support plate, plastic deformations can be forced in the
support plate in the case of overloads, for instance also as a
result of local rigidities, such as tapering regions of the support
plate. This results in a reduction in the loading of the
functionally important components of the support plate.
[0010] The support plate which is proposed according to the
invention is designed, in particular, in such a way that at least
one crack, that is to say a partial fracture or a complete fracture
of the support plate, is produced in the case of more than 150,000
load changes with accelerations over 400 m/s.sup.2. Accelerations
of this type do not occur during the normal vehicle operation. In
contrast, no fractures or cracks may be produced in the case of
accelerations below 300 m/s.sup.2. After the occurrence of at least
one fracture in the support plate which is proposed according to
the invention, the response characteristic of the generator
changes, as a result of which the maximum load is reduced on
account of damping effects which are produced.
[0011] Should the fracture faces not rub against one another after
the fracture of the support plate, this is associated with a loss
of friction energy. However, a completely fractured or partially
fractured support plate will have a lower rigidity in comparison
with an intact, that is to say unfractured, support plate. A
reduced rigidity of the support plate leads to greater deformations
of the latter and, as a result, additionally to damping potential
which results in addition to the damping potential which exists at
the fracture face. It is a further positive effect that the
transmission characteristic of the generator can be influenced
positively by the lower rigidity of the support plate. This effect
is substantially independent of whether the fracture faces of the
support plate rub against one another or whether this is not the
case.
[0012] With regard to the pitch circle of the support plate screws,
it is to be aimed for that it corresponds to the pitch circle of
the holes which are formed in the support plate, that is to say the
two pitch circles have identical dimensions.
[0013] In that design variant of the support plate proposed
according to the invention which is provided with notches at
defined points, it is to be aimed for that the geometry of the
notch is designed in such a way that said notch has a stress
concentration factor of K.sub.t>2.0.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In the following text, the invention will be described in
more detail using the drawing, in which:
[0015] FIG. 1 shows a longitudinal section through a generator,
[0016] FIG. 2 shows the plan view of a conventionally configured
support plate,
[0017] FIG. 3 shows a first design variant of the support plate
which is proposed according to the invention,
[0018] FIG. 3a shows the changing macroscopic geometry of the
support plate in accordance with the first embodiment according to
FIG. 3,
[0019] FIG. 4 shows a further, second possible embodiment of the
support plate which is proposed according to the invention,
[0020] FIG. 4a shows the change which is produced in the
macroscopic geometry of the support plate in accordance with the
second embodiment according to FIG. 4,
[0021] FIG. 5 shows a further, third possible embodiment of the
support plate which is proposed according to the invention,
[0022] FIG. 5a shows the changing macroscopic geometry of the third
embodiment (shown in FIG. 5) of the support plate which is proposed
according to the invention,
[0023] FIG. 6 shows a horizontal sectional profile through the
support plate,
[0024] FIG. 7 shows a sectional profile in accordance with the
sectional profile A-A which is shown in FIG. 6,
[0025] FIG. 7a shows the plastic deformation which is produced in
the sectional plane in accordance with the illustration in FIG.
7,
[0026] FIG. 8 shows a vertical section through the support
plate,
[0027] FIGS. 9 and 9a show the illustration of fracture faces which
are produced during the complete or partial fracture of the support
plate which is proposed according to the invention, and
[0028] FIGS. 10 and 10a show macroscopic geometry changes which are
produced in the support plate which is proposed according to the
invention, in the sectional plane of the section B-B in accordance
with FIG. 6.
DETAILED DESCRIPTION
[0029] The illustration according to FIG. 1 shows a section through
an electric machine 10, configured here as a generator or
three-phase generator for motor vehicles. Said electric machine 10
has, inter alia, a two-part housing 13 which consists of a first
bearing plate 13.1 and a second bearing plate 13.2. The first
bearing plate 13.1 and the second bearing plate 13.2 receive a
stator 16 between them, which stator 16 firstly consists of a
substantially circularly annular stator iron 17 and in the radially
inwardly directed, axially extending grooves of which a stator
winding 18 is inserted. Said annular stator 16 surrounds a rotor 20
with its radially inwardly directed grooved surface, which rotor 20
can be configured as a claw pole rotor. The rotor 20 consists,
inter alia, of two claw pole plates 22 and 23, on the external
circumference of which claw pole fingers 24 and 25 which extend in
the axial direction are arranged. The claw pole plates 22 and 23
are arranged within the rotor 20 in such a way that their claw pole
fingers 24 and 25 which extend in the axial direction alternate one
another on the circumference of the rotor 20. This results in
magnetically required intermediate spaces between the oppositely
magnetized claw pole fingers 24 and 25 which are called claw pole
intermediate spaces. The rotor 20 is mounted rotatably in the first
and second bearing plates 13.1 and 13.2 by means of a shaft 27 and
in each case one antifriction bearing 28 which is situated on in
each case one rotor side.
[0030] The rotor 20 has a total of two axial side faces, to which
in each case one ventilator 30 is fixed. Said ventilator 30
consists substantially of a plate-shaped or disc-shaped section,
from which ventilator vanes emanate in a known manner. The
ventilator 30 serves to make an exchange of air possible via
openings 40 in the bearing plates 13.1 and 13.2 between the outer
side of the electric machine 10 and the interior of the electric
machine 10. To this end, the openings 40 are provided substantially
at the axial ends of the bearing plates 13.1 and 13.2, via which
openings 40 cooling air is sucked into the interior of the electric
machine 10 by means of the ventilator 30. Said cooling air is
accelerated radially to the outside by the rotation of the
ventilator 30, with the result that said cooling air can pass
through the winding projection 45 which is permeable to cooling
air. The winding projection 45 is cooled by this effect. After
passing through the winding projection 45 or after flowing around
said winding projection 45, the cooling air follows a path radially
to the outside, through an opening which is not shown in FIG.
1.
[0031] Furthermore, it is apparent from the illustration in
accordance with FIG. 1 that a protective cap 47 which protects
various components against environmental influences is situated on
the right hand side. Thus, for example, this protective cap 47
covers a slip ring assembly 49 which serves to supply an exciter
winding 51 with exciter current. A cooling body 53 which acts here
as a positive cooling body is arranged around said slip ring
assembly 49. The second bearing plate 13.2 acts as what is known as
a negative cooling body. A connecting plate 56 is arranged between
the second bearing plate 13.2 and the cooling body 53, which
connecting plate 56 serves to connect negative diodes 58 which are
arranged in the bearing plate 13.2 and positive diodes (not shown
here in this illustration) in the cooling body 53 to one another
and therefore to realize a bridge circuit which is known per se. A
support plate of the electric machine 10 is denoted by designation
59 in FIG. 1.
[0032] A support plate in accordance with the prior art which is
used on an electric machine can be gathered from the illustration
in accordance with FIG. 2.
[0033] The support plate 60 which can be of rectangular, round or,
as shown in FIG. 2, square configuration comprises a through
opening 64 and a number of fastening openings 62. The fastening
openings 62 can be produced as punched holes, as drilled holes with
or without threads, or the like. The antifriction bearings 28 which
are shown in section in accordance with FIG. 1 are fixed in the
housing of the electric machine 10 by way of the support plate 60
in accordance with the illustration in FIG. 2. It is apparent from
the illustration in accordance with FIG. 2 that the support plate
60 which is shown there is of planar configuration in relation to
its outer and its inner borders.
[0034] FIG. 3 shows a support plate which is proposed according to
the invention and is illustrated in a first design variant.
[0035] It is apparent from the illustration in accordance with FIG.
3 that the opening 64 has an internal diameter 80 and contains a
number of fastening openings 62. A first outer notch 66 and a
second outer notch 68 which lies opposite the former are situated
in each case in a 6 o'clock arrangement and 12 o'clock arrangement
on the outer edge of the support plate 60 in accordance with the
illustration in FIG. 3. The first outer notch 66 and the second
outer notch 68 could also be configured to be turned by 90.degree.,
that is to say could be configured in the 3 o'clock and the 9
o'clock arrangement. Two outer notches 66, 68 which lie opposite
one another are preferably formed on the support plate 12 in its
first embodiment.
[0036] As is apparent from the illustration in accordance with FIG.
3a, cracks 70 which run from the notch bottom of the first and/or
the second outer notch 66 and/or 68 inward toward the internal
diameter 80 are produced during operation of the generator and
during mechanical loading of the support plate 60. Said cracks 70
represent a macroscopic change in the geometry of the support plate
60 and convert the mechanical loadings into precisely the cracks
70, with the result that loading peaks can be absorbed not by the
components of the electric machine 10 in accordance with the
illustration in FIG. 1, but rather substantially by the support
plate 60.
[0037] The support device 60 is preferably configured to be
plate-shaped, that is to say as a support plate.
[0038] It is to be noted in relation to the cracks 70 which extend
from the notch bottom of the outer notches 66 and 68 in the radial
direction toward the internal diameter 80 of the central opening 64
that the faces which delimit the crack 70 are relatively rough and
brittle and accordingly do further damping work in the context of
the present invention by rubbing on one another and accordingly
absorbing oscillating accelerations with the acceptance of a slight
temperature increase.
[0039] A further, second design variant of the support device which
is proposed according to the invention and is configured to be, in
particular, plate-shaped can be gathered from the illustration in
accordance with FIG. 4.
[0040] FIG. 4 shows that, in addition to the first outer notch 66
and the second outer notch 68 on the external circumference of the
plate-shaped support device 60, notches which lie opposite one
another, that is to say a first inner notch 72 and a second inner
notch 74, are also configured on the internal diameter 80 of the
central opening 64. In an analogous manner to the first outer notch
66 in the 12 o'clock position, the first inner notch 72 is likewise
situated in the 12 o'clock position on the internal diameter 80 of
the central opening 64. The same applies to the second inner notch
74 which, analogously to the second outer notch 68, is situated in
the 6 o'clock position on the internal diameter 80 of the central
opening 64. It goes without saying that both the inner notches 72,
74 and the outer notches 66 can be arranged in each case turned by
90.degree. with respect to one another.
[0041] FIG. 4a shows the crack pattern which is produced of the
cracks 70 in the case of mechanical loading of the support device
60 which is proposed according to the invention and is preferably
configured to be plate-shaped. On account of the small remaining
material web between the notch bottoms which face one another of
the first outer notch 66 and the first inner notch 72 and the
second outer notch 68 and the second outer notch 74, relatively
short cracks 70 extend, as indicated in FIG. 4a, between the notch
bottoms which in each case point toward one another.
[0042] The faces which are produced and delimit the cracks 70 have
a relatively high roughness, which is favorable with regard to
additional damping work, via which oscillating accelerations can be
dissipated.
[0043] A further, third design variant of the support device 60
which is proposed according to the invention and is configured to
be, in particular, plate-shaped can be gathered from the
illustration in accordance with FIG. 5. In contrast to the first
design variant in accordance with FIG. 3 and the second design
variant in accordance with FIG. 4, the support device 60 which is
proposed according to the invention and is configured to be
plate-shaped has, in accordance with FIG. 5, shell-shaped openings
76, 78 which are oriented so as to lie opposite one another in the
solid material of the support device 60. This results in material
webs which extend in each case from the ends of the openings 76 and
78 and extend in the radial direction both to the external
circumference of the support device 60 which is configured to be
plate-shaped and also to the internal diameter 80 which delimits
the central opening 64. Excessive loadings are produced in said
remaining, relatively short material sections in the case of
mechanical loading of the support device 60 which is proposed
according to the invention, on account of oscillating accelerations
which occur, which excessive loadings lead to the crack courses 70
which are shown in FIG. 5a, firstly in the direction of the
external circumference and the support device 60 and secondly in
the direction of the internal diameter 80 of the central opening
64.
[0044] Fastening openings 62 are a common feature of all the design
variants in accordance with FIGS. 3 to 5 of the support device
which is proposed according to the invention and is configured to
be, in particular, plate-shaped. Said fastening openings 62 can be
simply punched holes, or they can be drilled holes which are
configured with or without internal threads. The pitch circle
diameters both of the pitch circle of the fastening openings 62 and
also that of the screws which penetrate the fastening openings 62
are preferably identical.
[0045] An illustration of the support device 60, in which a
horizontal sectional profile A-A is represented, can be gathered
from the illustration in accordance with FIG. 6.
[0046] FIGS. 7 and 7a show the support device 60 in the sectional
plane A-A, which support device 60 is shown in FIG. 6 with the
sectional profile A-A, is proposed according to the invention and
is configured to be, in particular, plate-shaped. It is apparent
from the sectional illustration in accordance with FIG. 7 that, in
the region of the central opening 64, the support device 60 has a
reduced thickness 84 in relation to its thickness 82, that is to
say a tapered section 84. The tapered region 84 which adjoins the
central opening 64 of the support device 60 which is configured to
be, in particular, plate-shaped results in webs 86 which lie
opposite one another and experience a plastic deformation 88 in the
case of a mechanical loading of the support device 60 which is
configured to be, in particular, plate-shaped, as is shown in FIG.
7a.
[0047] The plastic deformation 88 (shown in FIG. 7a) of those ends
of the webs 86 which lie opposite one another represents a
macroscopic change in the geometry of the support device 60 which
is configured to be plate-shaped, by way of which change the
stresses can be dissipated which are produced in the support device
60 which is configured to be plate-shaped in the case of mechanical
loading of the latter, and accordingly a complete fracture or a
partial fracture is accepted of the support device 60 which is
configured to be, in particular, plate-shaped, in order as a result
to protect the components of the electric machine 10 in accordance
with the sectional illustration in FIG. 1 against excessive
mechanical loadings in the frequency range mentioned.
[0048] FIG. 8 shows a sectional profile A-A, B-B. FIG. 9 shows the
profile through the support device 60 before the fracture, whereas
FIG. 9a represents the sectional profile after the occurrence of a
fracture in the support device 60 which is proposed according to
the invention.
[0049] A sectional profile B-B in accordance with the sectional
illustration in FIG. 8 can be gathered from FIGS. 10 and 10a.
According to the sectional profile B-B as shown in FIG. 10, a
planar-side notch 92 is made on one of the planar sides 94 and 96
of the support device 60 which is configured to be, in particular,
plate-shaped. As a result, a reduced thickness is produced between
the notch bottom of the planar-side notch 92 and the planar side 94
which lies opposite it. A crack 70, as indicated in the
illustration in accordance with FIG. 10a, extends precisely in this
reduced thickness in the case of mechanical overloading of the
support device 60 which is proposed according to the invention and
is preferably configured to be plate-shaped. The crack 70 extends
from the notch bottom of the planar-side notch 92 to the planar
side 96. As an alternative to the position (shown in FIGS. 10 and
10a) of the planar-side notch 92 on the first planar side 94, it
goes without saying that the planar-side notch 92 can also be
formed on the opposite second planar side 96 of the support device
60 which is proposed according to the invention and is configured
to be, in particular, plate-shaped.
[0050] It is to be noted with respect to FIGS. 3, 4, 5 and 10 that
the notches which are shown there, whether they are outer notches
66, 68, inner notches 72, 74 or planar-side notches 92, are all
preferably configured with a stress concentration factor of
K.sub.t>2.0. The stress concentration factor x.sub.Kt is defined
as the quotient from maximum loading and nominal loading.
[0051] In the embodiments shown in FIGS. 3, 4, 5, 7 and 9 of the
support device 60 which is proposed according to the invention and
is configured to be, in particular, plate-shaped, it is to be noted
that the geometry of said support device is configured in such a
way that the support device 60 fractures when more than 150 000
load changes at accelerations over 400 m/s.sup.2 occur. The support
device 60 which is proposed according to the invention and is
configured to be, in particular, plate-shaped is preferably
dimensioned in such a way that it does not fracture in the case of
accelerations below 300 m/s.sup.2. After the fracture or partial
fracture of the support device 60 which is proposed according to
the invention as a result of at least one crack 70 occurring, the
response characteristic of the electric machine 10 changes, as a
result of which the maximum load is reduced by way of damping
effects.
[0052] If the fracture faces 90 which are shown in FIG. 9a no
longer rub against one another after the fracture, part of the
friction energy, in which energy is dissipated, is lost. However, a
fractured or partially fractured support device 60 will have a
lower rigidity than an intact support device 60. A reduced rigidity
of the support device 60 in turn leads to somewhat greater plastic
deformations 88, as is shown in an exaggerated manner in FIG. 7a,
and additionally leads, as a result, to damping which is to be
considered to be additional damping in relation to the damping
which can be achieved by way of the fracture faces 90.
* * * * *