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Патент USA US3079801

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March 5, 19673
3,079,791
K. MOSWALD
PICK up FOR TORQUE-MEASURING APPARATUS
Filed Sept. 15, 1958
6 Sheets-Sheet 1
March 5, 1963
7
K. OSWALD
3,079,791
PICK UP FOR TORQUE—MEASURING APPARATUS
Filed Sept. 15, 1958
s Sheets-Sheet 2
Fig.4
March 5, 1963
K. OSWALD
3,079,791
PICK UP FOR TORQUE-MEASURING APPARATUS '
Filed Sept. 15, 1958
’
I
e Sheets-Sheet a
March 5, 1963
‘K. OSWALD
3,079,791
PICK UP FOR TORQUE'MEASURING APPARATUS
Filed Sept. 15, 1958
e Sheets-Sheet 4
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March 5, 1963
3,079,791
K. OSWALD
PICK UP FOR TORQUE—MEASURING APPARATUS
Filed Sept. 15, 1958
6 Sheets-Sheet 5
March 5, 1963
'
K. OSWALD
3,079,791
PICK UP FOR TORQUE-MEASURING APPARATUS
Filed Sept. 15, 1958
e Sheets-Sheet e
72
Hg. 19
z
Hg. 15
ice
Federated Perla-r. E3, 1983
2
mentioned technical drawbacks, it is possible in a special
Sap/"9,7115.
embodiment to construct a pick-up in which the stator,
PHIK UP FUR TGRQUE-MEASUREQG APPARATUS‘;
Karl Oswald, Sari-zen, Switzerland, nssignor to G. A.
Messen-Jasehin, Sarnen, Switzerland, a corporation of
Switzerland
Filed Sept. 15, F958, Ser. No. 76%,94?
independently of the rotor formed by the toothed rims, is
pressed resiliently against the running surfaces of the
rotor, so that the distance between the magnet poles of the
magnet systems mounted on the stator and the toothed
rims is maintained constant as the rotor turns.
Claims priority, application dwitzerland Sept. 14-, 1%’?
11 Claims. (Cl. 73-136)
Constructional examples of the subject of the inven
tion are represented in the accompanying drawings, where
The invention relates to a transmitter or pick-up for 10
a torque-measuring instrument, the transmitter or pick
up having toothed rims which are secured at spaced posi
in:
FIGURE 1 shows a part of an axial section through a
pick-up,
FIGURE 2 a detail of the pick-up in an axial section
tions to a shaft, the torque of which is to be measured.
The rims are co-axial with the shaft and they co-operate
With a stator to bring about, in the case of each toothed
rim, a cyclic variation in some electrical parameter. The
two cyclic variations are compared in further apparatus
which gives an indication of the torque on the shaft. This
may involve supplying to an indicator two cyclically vary
offset relatively to the section according to FIGURE 1,
FIGURE 3 a detail of FIGURE 1 in end view,
FIGURE 4 a part of the stator of FIGURE 1 in end
view,
FIGURE 4:: a part of a radial section through an
alternative form of pick-up rotor,
FIGURE 5 a part of an axial section through a sec
ing voltages, induced in two dilferent magnetic ?elds, and 20
ond example of the pick-up according to the invention,
having an indicator which gives a torque indication in
FIGURE 6 an end view of the pick-up according to
dependence upon the phase difference between the two
FIGURE 5 on a smaller scale,
FIGURE 7 a detail of FIGURE 5 ‘in plan on a larger
voltages.
In known pick-ups of this type, each toothed-rim carrier
is mounted on the shaft by means of a cylindrical or con
25
ical surface. Due to the axial extent of this surface, which
in practice cannot be brought to bear completely against
the cooperating surface of the shaft, the exact extent of
the measuring section, i.e. the axial distance apart of the
supporting positions of the two toothed rims on the
shaft, is unknown, which may result in errors of measure
ment. Furthermore, in the known pick-ups, the stator is
supported independently of the two toothed rims. The
often unavoidable eccentricity of the toothed rims with
respect to the shaft axis results in a variation of the dis
tance of the toothed rims from the stator parts in?uenced
by them during a revolution of the shaft, which likewise
leads to errors of measurement.
in the pick-up according to the invention, these disad
vantages are avoided. For this purpose, the pickup ac
cording to the invention comprising a shaft, ?rst and sec
ond toothed rims co-axial with the shaft, ?rst and second
cylindrical support members surrounding the shaft and to
which the ?rst and second toothed rims, respectively, are
?xed, ?rst and second ?xing means secured to the ?rst 45
and second support members, respectively, and making
substantially line contact with the shaft around ?rst and
second spaced peripheral lines on the shaft, whereby the
scale,
FIGURE 8 a third example of a pick-up according to
the invention in end view,
FEGURE 9 an wial section analogous ‘to FIGURE 5
through a fourth example of a pick-up according to the
invention,
FIGURE 10 an axial section of a pick-up according to
the invention with a ?rst example of a device for zero
point calibration,
FIGURES 11 and 12 in side view and end view,
respectively, the pick-up with a second example ‘of a de
vice for zero-point calibration, and
FIGURES l3 and 14 in side view and end view the
pick-up with a third example of a device for zero-point
calibration.
in FIGURES 1-4 of the drawings, the torque on a
shaft 1 is to be measured by reference to the amount
by which one end of a test section a of the shaft turns
relative to the other end. Mounted on said shit 1, at
a small distance apart within the measuring section a are
two toothed rims 2 and 3, the teeth of which are of equal
pitch and of magnetic material.
The toothed rim 2
is formed as end ?ange of a cylindrical support 4-, which
is mounted co-axially ‘and with radial spacing relatively
first and second rims will turn in accordance with the turn
to the shaft 1. The end of the support 4 carrying the
ing of the shaft at said first and second lines, respectively,
toothed rim 2 is supported on the shaft 1 by means of a
ring 5 mounted on the shaft so as to turn relative to the
a stator adjacent the toothed rims, magnetic means in the
stator for co-operating with the teeth for the generation
of alternating current when the shaft turns, and bearings
engaging the stator and one of the support members at
spaced locations distributed around the entire circum
ference of said one support member and supporting the
shaft. The other end of the support 4 is held by a ring
é, the inner edge of which ‘remote from the support 4
is bevelled. This bevelling and vthe adjacent end face
of a clamping ring 7 partly de?ne an annular recess be
tween the two rings 6 and ‘7 and the shaft 1, in which
ecess lies ‘a ring 3 of round wire. By means of screws,
stator in space and locating it both axially and radially
not shown, the clamping ring 7 is ?xed to the ring 6,
with respect to said one support member.
the wire ring 8 being pressed against the shaft 1. The
Since the toothed rims are each connected to the shaft
only on a circular, i.e. peripheral, line on the latter, the 60 wire ring 3 makes line contact with the shaft at the pe
ripheral line on the shaft 1 representing one boundary of
length of the measuring section situated between these two
the measuring section a, and against said shaft, so that
peripheral lines is exactly determinable. Measuring errors
the support a‘- and with it the toothed rim 2 is ?rmly con
due to eccentric mounting of the toothed rims on the shaft
nected to the shaft 1 at the desired position. The second
cannot occur, since the stator is mounted on one of the
toothed rim 3 is connected to one end of a cylindrical
toothed rim supports itself.
shell 9, surrounding the shaft 1 with radial spacing and
co-axially, the other end of said shell being fixed to the
external periphery of an annular disc 10 coaxial with the
runs in the stator. Such an arrangement, however, is_n_ot
shaft l. The annular disc 19 is anchored by its inner
always ree from transmission errors, and results in such
errors even if the two transmission elements, namely the 70 edge to a ring 11, the inner edge of which, remote from
the disc, is bevelled. By means of screws, not shown, a
rotor toothed rims and the pick-up magnet systems on the
clamping ring 12 is ?xed to the ring 11, and together
stator lie very close together. In order to avoid the above
In the constructions of torque pick-ups known hereto
fore, the arrangement is always such that the pick-up rotor
3,079,791
3
Al.
with the bevelling on the ring 11 partly de?nes an an
ul'ar recess facing the shaft 1. In this recess lies a ring
gether until after their ‘assembly in the pick-up and ?xing
resenting the corresponding limit of the measuring sec
of the toothed rim 3 to its support 9‘, 10.
The ball bearings 16 and 24', like the ring 25 carrying
the magnet systems Bl-Bé, are adjusted before the ap—
plication of the cover plates 20, 21. The magnet systems
tion a, and thus connects, the support 9, 10 with its
toothed rim 3 ?rmly to the shaft at the desiredposition.
displacement is adjusted, for which the measuring instru
Mountedin the toothed rim 2 at intervals apart on the
ment, not shown, indicates zero.
13 of round wire, which like the wire ring 8, is pressed
on the shaft 1 along a peripheral line’ on the latter, rep
liq-B4 are adjusted so that for zero torque a desired phase
_
In the operation of the pick-up, due to the twisting of
circle are bushes 14, each of which has an end part which
is eccentric relative to the bush axis and which carries a 10 the measuring section a or of the toothed rims 2 and 3,,
ball bearing 15.
.
,
occurring during the rotation of the loaded shaft 1, cyclic
variation takes place of the magnetic ?eld of the magnet
“On the external periphery of‘ the support 40f the
toothed rim 2 are supported a plurality of ball bearings
systems of ‘the stator, whereby corresponding alternating
16, axially parallel \to the ‘shaft axis arid each mounted
on "an eccentric end part of a bush 17.
voltages are generated in the coils 27 and 29. The
phase difference between the voltages is used for indicat
ing the torque e?ective on the shaft 1.
In the example described, the supports of the toothed
mims 2 and 3 are clamped on the measuring shaft 1' by
The bushes 17
are mounted in alstator, disc 18 and can be swung about
pivot axes’ of arms .19 (FIGURE .3) for radial adjust
ment of the ‘bearings ,16. The arms 19 arepermanently
carried by the stator disc. The stator disc 18, supported
means of wire rings 8 and 13 which do not, in fact, fol
low a complete circle but are split, like piston rings.
It is evident that instead of rings of round wire, rings
wedge-shaped in cross-section or individual 'balls dis
tributed around the periphery of the shaft could’be‘used;
radially on the support 4 by means of the bearings 16
is prevented from. rotating by means .BQZYShIOWR» Such
means may take a form_-similarto;-that‘described below
and illustrated in FIGUREY6. ’ The stator disc 18 is pro
In the exampleshown, the magnetic ?ux in. the magnet
vided with detachable cover plates ‘20 andZl. In an
inner ?ange 22 (FIGURE 2) of the stator disc 18, v7co
axial with the shaft, rotatably adjustable pivots 2} are
systems is varied cyclically for. generating the desired ale
ternating voltages; similarly, however, the magnitudeof
mounted between the bearings 16, the, end parts of which
another electrical parameter (for example inductance or
capacitance) could be .varied cyclically by the relative
pivots, projecting towards the shaft 1 from the ?ange
22..are eccentric vand each carry a ball'bearing 24. _The
outer rings of said bearings bear against a radial surface
‘on the support 4, so that by means of said bearings '24,
the stator is supported axially on the support 4.
30
blindbores 2A of equal depth, diameter’ and spacing, so
that the rotor parts between the teeth simulate. salient
l ‘
Magnet systems A1-A4 (FIGURE 1) with pole shoes
26 and induction coils 27 are provided at equal inter
vals apart on a circle,»the pole shoes-"26 facing the pe
riphery of the toothed rim 2. Between the magnet sys
tems A1—_A4, fourv magnet systems 131-134 with pole shoes
28 and induction coils 29 are provided, the pole shoes
28 facing the periphery, of the. toothed rim ,3‘. Between
the magnet systems A; and B; there isprovided an iden
tic-a1 magnet system vC with pole shoes facing 'one of the
toothed rims, while between the magnet systems A1 and
B1 is mounted afurther magnet system D with pole shoes
facing the other toothed rim.’ The arrangement, of the
magnet systems on the disc 18 oryping 2'5 isgindicated
in FIGURE 4. The magnet systems A1 to A4 and C and
D are?xed on the stator disc '18 by means of bolts passing
through round holes in the stator disc and-through arcuate
slots in a ring 25 which islet into a recess in the stator
,disc. The remaining magnet systems are ?xed on the
ring 25 ‘which can be turned about its axis, as far, as per
movement between stator and toothed rims.
As shown in FIGURE 40, instead of providing salient
teethion the rotor, .the parts 2 and 3 may be formed with
teeth.
35
.
.
.
s
..
1
_
-
.
In the example according to FIGURES S to 7, 30 is
the measuring shaft with test section a.‘ Two toothed
rims 31 and 32 are mounted on said. shaft 30 ‘at a short
distance apart. Thevtoothed rim 31 is formed as end
?ange of a cylindrical support 33, ‘which isimounted co
axially and with a radial spacing relative to shaft'?tl. One
end of the support 33 is ?xed on shaft 31) by‘ means of a
clamping ring 34 of round wire. The wire ring 34 makes
‘line contact with the shaft at a peripheral 'line on shaft 30
so ‘that the support 33 and with it the toothed rim ‘3-1
can be rigidlyconnected to the shaft 3% atthe desired
position, i.e. at the end of the measuring section a. The
second toothed rim 32- is secured to. one end of a cylin-V
drical shell 35, surrounding the shaft 3% with radial spac
ing and co-axially, the other end of said shell being
secured'to the external periphery of an annular disc 36
co~axial with the shaftEil. The annular disc'36 is fixed
mitted by the ends of the arcuate slots, in order to ad
.to the shaft 30 by means of a clamping ring 37 of round
just the positions of the magnet systems A1 to, A4 [and C
wire like the support 33 around a peripheral line on said
and D relative to the other magnet systems. The magnet
shaft representing the corresponding limit of the meas
systems A, and C, as well as A1 and D serve for calibra 55 uring section a; thus the support 3'5, 36 withpits toothed
nim 32 is rigidly connected to the shaft 36 at the desired
tion ‘and Checking of the measuring instrument. Since
position. Mounted in the toothed rim 31, spaced apart
the angular. positions, around the ring 25, of the mag
on a circle, are pins 38 (FIGURE 5 only one visible).
net systems A1 and C, for example, are accurately known,
The end part of each pin projecting from the toothed rim
then it is known what the phase difference ‘between the
potentials from these two magnet systems really is. It
is suflicient, then, to apply the two potentials to the meas
uringinstrument, which gives an‘indicati-on of the phase
difference. If the indicated phase difference is not the
same as the accurately known phase difference, the am
pli?cation of the potentials by the instrument ‘requires
adjustment until exact correspondence is obtained. The
magnet systems A1—A4 and 31-134 serve for torque in
dioation.
.
.
60 31 is eccentric relatively to the pin axis and carries a ball _
bearing 39. The toothed rim 32 ?xed to the shell 35- is
mounted on said ball bearings 39. The eccentric pin 38
permits adjustment of the bearings 39 in the radial direc- '
tion.
.
t
.
The two toothed rims 31 and 32 are each provided on
their periphery with a cylindrical bearing surface 41) of
the same diameter; a further bearing surface 41, situated
in a plane at right-angles to the shaftaxis is also provided
on each-of the'end sides, facing away from each other,
‘Tne'two toothed rims‘ land-3 are made by screwing 70 of the twov toothed rims 3i and 32. A segment-shaped
their blanks together and machining them simultaneous—
stator carriage $3 is mounted by means of ball bearings
iv. The support 4 is machinedat the same time so that
42 on said bearing surfaces 49, 41 of thetwo toothed
accurate round running of 'the ball bearings 16 with
rims 31, 32. In the radial direction, the stator carriage
respect to the surface of the support-4,- upon which they
43 is pressed against the bearing surfaces 40 by means
bear'is ensured. The toothed rims, remainiscrewed to
- of a resilient system 44a (e.g. suitable springs), which is
3,679,791
5
supported at a ?xed point, situated outside the pick-‘1p
so that any play between bearing rollers and cylindrical
bearing surface is avoided. In the axial direction, each
of the two ball bearings 4-2, running on the bearing sur
face 41 of the toothed rim 31, is pressed against the hear
ing surface 41 of the toothed rim 31 by means of a spring
44b (FIGURE 7), supported on the carriage 43 itself
and engaging a pivotal arm 4-5 carrying the ball bearing.
The carriage 43 carries the magnet systems 46, the mag
net poles 47 of which stand opposite the toothed rims
3i and 32.
If, due to a displacement of the middle of the shaft 353
5
in the arrangement of a stator supported resiliently
against the rotor, it is not absolutely essential for the
two pick-up toothed rims 3?. and 32 to be mounted at
the smallest possible distances apart. The pick-up toothed
rim 33 may be arranged at the distance a from the
pick-up toothed 'im 32, in which case the shell tube 35
may be omitted; i.e. two mechanically independent pick
up and receiving systems may be mounted on the torque
transmitting shaft 3%. in this case, therefore, one or more
stator carriages each associated with both toothed rims,
are not provided, but one or more separate carriages are
provided for each toothed rim.
in the transmission of torque and power via shaft
or to non-circularity, produced for example by clamping
lines, two different principles may be used for their
of the toothed rims, the two rotor toothed rims 3f, 32
run eccentrically, the carriage 43 adapts itself to these 15 measurement. The first principle is based on the fact
that the twisting of the shaft occurring in the transmis
movements, so that the pick-up gap between the toothed
rims and the magnet poles remains constant and no
?uctuations can occur in the transmitted measured values.
The only condition which must be made from the manu
facturing side is that the two cylindrical bearing surfaces
443 must be absolutely parallel to each other. This can be
obtained, however, without trouble in manufacture by
machining ‘die two surfaces together in one clamp on
the lathe. The arrangement described makes it possible
to manage with one set of magnet systems; at the
s .e time, by the incorporation of an adjusting system
48 (FIGURE 6), consisting of screwthreaded posts 48A
sion of torque and power is taken as a measure of the
power transmission. The second method is
stantially on the fact that strain gauge strips
to the surface of the transmission shaft, and
lengthen or shorten during the twisting of
based sub
are applied
these strips
the power
transmitting shaft in accordance with the geometrical
angle of twist. The changes in length are so vetted into
voltage variations and these voltage variations are fed to
the indicating instrument by means of a slip-ring system
and suitable electrical transmission. Common to both
principles is the need for a satisfactory so-called zero
and 45-313 pivotally connected to the stator and a fixed sup
point determination, i.e. adjustment of the measuring in
port 48D, respectively and provided with left and right
struments to the condition of freedom of the transmis
sion shaft from torque. This requirement first of all
hand threads, respectively, in combination with a turn
buckle
The latter can be turned to effect movement
of the carriage around the rotor, whereby it is possible
to obtain a zero-point adjustment. When the turnbuckle is
not being turned, the posts 48A and 48B prevent the
stator from turning around the axis of the rotor. Similar
assumes that the transmission shaft has no frictional
torque, appearing as pre-stress in the transmission shaft
and produced by starting up, for example, of a ship’s
engine. That is to say, therefore, at the commencement
of calibration or zero adjustment, the shaft must be
or comparable means may be provided ‘in the other en -
brought to a stress-free condition, or the pre-stressed con
bodiments to adjust the position of the stator and to
prevent from rotating once it has been adjusted.
For a so-called internal compensation of transmission
errors, it has been found to be particularly advanta
geous, instead of a single transmission magnet system, to
arrange three or more such systems around the periphery
of the pick-up rotor. Such an arrangement is shown
in FIGURE 8, in which the construction of the individual
stator carriages 43 is the same as in the example last
described. in the arrangement as shown in FEGURE 8,
the three carriages 43 are so arranged that they can be
moved in the radial direction, while remaining constant
relatively to each other in th lr segmental or angular
spacing 06. For this purpose, the guiding of the carriages
43 is effected by means of bolts 49 running in radial
dition must be included as ?xed magnitude in the zero
point. if we now start from the fact that the shaft
itself is in a state of freedom from stress, then in the
slots. For zero-point adiustment, the stator ring db
carrying the radially slidable carriages 43 with the magnet
tion, the strain gauge measuring method can then lead to
systems can be turned about the center P. F1. ing of the
stator ring 5% is effected by means of clamping slit 52
co-operating with an eccentric 51..
in other respects, the construction according to PEG
if the measurement is based on the principle of the
twisted shaft, and the torque magnitudes are measured
by means of a phase displacement, occurring through the
mutual displacement of two pick-up toothed rims, there
URE 8 corresponds to that according to FEGURES 5-7,
exce t that here instead of a single spring 44a for press
ing the individual carriages 43 against their bearing sur
faces it), two such springs re provided.
A further example is shown in FIGURE 9. Here again,
the supports 33 and 35', 36 of the toothed rims 31 and
32 are ?xed on the shaft 30 by means of clamping rings
must be rotation of the rotor relative to the stator for
34 and 37, respectively.
Contrary to the previously
measuring method employing strain gauges, the zero-point
calibration can be undertaken in the static condition, i.e.
with the shaft at rest. Calibration with strain gauges,
however, is generally dependent upon stress and tempera
ture, so that accuracy of measurement can only be at—
tained with di?iculty over a large range. Generally, in
zero point calibration, a so-called precompensation of
measuring errors to be found in the temperature expan
sion of the apparatus, is undertaken, so that then the
actual zero is mready displaced by a mean error. if,
new, during the loaded state, the measurement deviations
do not occur
the assumed order of magnitude or direc
considerable errors in indication.
any indications to be obtained.
For zero-point calibra
tion, therefore, the transmission shaft must normally be
rotated and the speed must reach a value dependent upon
the transr -ission frequency. In normal ship’s drive, how
ever, the requirement of so-called dynamic calibration can
be satisfied in extremely few cases only, and a method
is therefore desirable for enabling zero calibration to
be carried out in the phase-displacement measuring meth
od but with the shaft stationary. The method described
in the following indicates a technically satisfactory way
of doing this.
stator carriage 55. in this case also, the stator carriage
is pressed resiliently against its bearing surfaces on the 70 The basic principle of the method is as follows: the
apparatus part acting as rotor in the working condition
rotor by means of a spring system, not shown, supporte
and rigidly connected to the transmission shaft is used
outside the pick-up. instead of the supporting bearings
as stator in t, a calibration method, while the apparatus
39 of the example first described, in this case a wire ball
part acting as stator in the normal working condition is
bearing 56 is provided between the two toothed rims
now used as rotor for zero-point calibration. In detail,
31 and 3M.
described examples, however, in this case there is pro
vided on each toothed rim only one conical bearing sur
face 5'3, upon which act ball bearings 54 mounted on the
the
3,079,791
%
this is-e?ected by the following device, shown in FIG
variable tip width of the tooth of the pick-up wheel.
URE 10. The ring 61, on which the magnet systems 62
are secured, is originally the stator part of the measuring
apparatus. A hollow cylinder 67 is formed integral with
the ring 61 and there is mounted on its external periphery
two slip rings 63, to which the phase-separated voltages
of the magnet systems 62 can be transmitted by means
Since the relative displacements of the two toothed rims
required for torque indication are in any event small,
any variation in the tooth tip widths very soon falsi?es
the measured result. This circumstance is counteracted
by using a tooth form in which ‘the tooth ?anks are
planes parallel to one another,‘so that variation in the
depth of cut of a tooth cannot produce any variation in
the tooth tip width. The result is that with teeth free
of electric leads. A resilient wheel 64 runs against the
inner surface 65 of the cylinder 67 in order to drive the
latter. An electric motor 66, mounted on a two part holder It) from pitch errors, the tooth tip widths remain constant,
66a to be secured to the transmission shaft, effects drive
even in the case of Variable tooth parts. Only such a
of the wheel 64 and the transmission of the rotary move
con?guration of the teeth permits transmission of the
ment to the part 67, '61 of the apparatus, which originally
was the stator, but for zero adjustment is the rotor of the
measuring apparatus. The electrical values are trans’
mitted to the measuring instruments by means of brushes
63A engaging the slip rings.
Since in the measuring
method described, phase differences are used for the meas
urements, slip-ring'transmission does not introduce any
transmission errors into the measurement itself, whereas
if voltage di?’erencesare to be measured, slip-ring trans
mission always gives rise to considerable transmission er
rors; From the standpoint of transmission’ accuracy,
therefore, the slip-ring ‘method can be used without ob
jection if, and this point is now important, after calibra
tion, by means of the slip rings, vthe line capacitance
resulting from‘the slip-ringlength and the slip-ring cross
sectionis compensated by a capacitance member to be
included in the line. The value of the transmission
phase displacement of the two pick-up wheels free from
error and independent'of mechanical effects.
I claim:
'
'
'
1. A pick-up for torque measuring apparatus, com
prising a shaft, ?rst and second juxtaposed toothed rims
in spaced relation ‘co-axial with the shaft whereof the
teeth are of equal‘pitch andare of magnetic material,
20 ?rst and second cylindrical support members surrounding
the shaft and to which the ?rst and second toothed rims,
respectively, are ?xed, ?rst and second ?xing means
secured to- the ?rst and second support members, re
spectively, and making substantial line contact with the
shaft around ?rst and second spaced peripheral lines
on the shaft, whereby the ?rst and second rims will turn
in accordance with the turning of the shaft at said ?rst
and second lines, respectively, a stator adjacent the
toothed rims, means connected to the stator for prevent
capacitance in the static zero-point calibration described 30 ing it from rotating when a measurement is to he made,
above can be ?xed, however, without di?iculty, and after
magnetic means in the stator for co-operating with the
zero-point calibration has been effected, the compensation
teeth for the generation of alternating current when the
capacitance member can be incorporated in the transmis
sion line or in the measuring part.
In the, example according to FIGURES 11 and 12, the
shaft turns, ball bearings engaging the stator and one of
the support members at spaced locations distributed
around the entire circumference of said one support
driving mechanism is also detachably mounted on the
member and supporting the stator in space and locating,
shaft by means of- a clamping holder 66a. The motor 65
drives the rim 67 of the stator by means of the resilient
it both axially and radially with respect to said one sup
port member, and eccentrics upon which the ball bear
ings are mounted and which are adapted to be turned
wheel 64. 'In other respects, this construction corresponds
to the example‘ described in the foregoing.
If, for technical process reasons, the driving mechanism
40
for adjusting the positions of the bearings.
2. A pick-up for torque measuring apparatus, compris
and the voltage take-o? device are to be mounted on the
ing a shaft, ?rst and second juxtaposed toothed rims in
shaft while it is at rest during zero-point calibration, it
spaced relation co-axial with the shaftwhereof the teeth
is possible-to proceed in accordance with the example
are of equal pitch and are of magnetic material, ?rst and
shown in FIGURES '13 and 14. A vertically adjustable on CA second cylindrical support members surrounding the shaft
shear arrangement 72 is mounted-on a ground beam 71
and to which the ?rst and second toothed rims, respec
so that .by spindle adjustment-73, the supporting block
tively, are ?xed, ?rst and second ?xing means secured'to '
74 can be raised or lowered. ' By means of this shear ar
the ?rst and second support members, respectively, and
making substantial line contact with the shaft around ?rst
and second spaced peripheral lines on the shaft, whereby
rangement, it ' is now possible 'to support the ground
beam 71 positively against the shaft 75. A bracket 76, 50
rotatable on the axis 76a, is coupled to the adjustable
the ?rst and second rims will turn in accordance with the
shears 72 so that the friction wheel '77, mounted on the
turning of the shaft at said ?rst and second lines, respec
shaft of the driving motor 78, is brought into frictional
tively, a stator adjacent the toothed rims, means connect
contact with the inner surface of the cylinder disc 79.
ed to the stator for preventing it from rotating when a
In the pick-up constructions so far described, the main
a measurement is to be made, magnetic means in the
principle of which consists in that the generation of
stator for co-operating with the teeth for the generation
the'voltagestakes place inductively, an important ques- , ' of alternating current when the shaft turns, bearings en
gaging the stator and one of the support-members at
' tion has been left unmentioned, namely that of the opti
mum tooth-form of the pick-up Wheels. Extensive the
spaced locations distributed around the entire circumfer
oretical and practical investigations have shown that the 60 ence of said one support member and supporting the
stator in space and locating itboth axially and radially
pick-up wheel, if it is'not to indicate any simulated phase
displacements, must ?rst of all be free from pitch errors.
with respect to said one support member, turnable
This requirement. for freedom from pitch errors is solved
eccentrics mounted on a ?rst of the support members and
from the point of view of process technique in modern
ball bearings mounted on the eccentrics and engaging a,
gear-cutting machines, so that this basic requirement can 65 bearing surface on the second support member, whereby
be regarded as satis?ed in construction. Much more
said second support member is supported with respect
di?icult from the point of view of manufacturing tech
to said ?rst support member while being rotatable rela
tive thereto.
'
nique, however, 'is the second requirement of absolute
circular'running of the toothed rim and the associated
3. A pick-up for torque measuring ‘apparatus, compris
constant‘ depth of cut of the individual teeth of the pick
ing a shaft, ?rst and second juxtaposed toothed rims in
spaced relation co-axial with the shaft whereof “re teeth
up. wheel. As soon, in fact, as the tooth parts ?uctuate,
in normally pro?led tooth flanks, variations occur in the
are of equal pitch and are of magnetic material, ?rst and
tooth ‘tip width which cause the magnetic flux formed
second cylindrical support members surrounding the shaft
between the magnet system-and tooth of the pick-up
and to which the ?rst and second’ toothed rims, respec
wheel to-undergo a phase displacement, produced by the
tively, are ?xed, ?rst and second ?xing means secured to
3,079,791
the ?rst and second support members, respectively, and
making substantial line contact with the sha?t around
?rst and second spaced peripheral lines on the shaft,
whereby the ?rst and second rims will turn in accordance
with the turning of the sha?t at said ?rst and second lines,
7. A pick-up according to claim 5, wherein the stator
comprises a carriage in the shape of a segment of a circle,
which carriage is urged towards the toothed rims by said
spring means.
8. A pick-up according to claim 7 and further com
prising means for adjusting the position ‘of the carriage
by turning it about the sha?t axis.
9. A pick-up according to claim 5, wherein the stator
when a measurement is to be ‘made, a set of magnet sys~
corn-prises a plurality of carriages in the shape of a seg
terns ?xed to the stator for the generation of alternating
current when the shaft turns, pole shoe-s of said magnet 10 ment of a circle equally spaced around the shaft axis,
which carriages are urged towards the toothed rims by
systems presented to the teeth of one rim, a ring mounted
respectively, a stator adjacent the toothed rims, means
connected to the stator for preventing it from rotating
in the stator for turning relative to the stator, another
set of magnet systems secured to the ring for the gen
eration of alternating current when the shaft turns, pole
shoes of those magnet systems presented to the teeth of
the other rim, the magnet systems of the two sets alter
nating at equal intervals around a circle centered on the
shaft taxis, and bearings engaging the stator and one of
the support members at spaced locations distributed
around the entire circumference of said one support mem
ber ‘and supporting the stator in space and locating it
both axially and radially with respect to said one support
member.
4. A pick-up according to claim 3 and further compris
said spring means.
10. A pick-up according to claim 9, wherein the ?xed
abutment member is a ring which serves as an abutment
for the spring means of ‘all the carriages and which is
mounted for turning about the shaft axis.
11. A pick-up for torque measuring apparatus, com
prising a shaft, ?rst and second juxtaposed toothed rims
in spaced relation coaxial with the shaft whereof the
teeth are of equal pitch and ‘are of magnetic material,
?rst and second cylindrical support members surrounding
and to which the ?rst and second toothed rims, respec
tively, are ?xed, ?rst and second ?xing means secured to
the shaft and to which the ?rst and second toothed rims,
respectively, are ?xed, ?rst and second ?xing means se
cured to the ?rst and second support members, respective
ly, and making substantial line contact with the sha?t
around ?rst ‘and second spaced peripheral lines on the
shaft, whereby the ?rst and second rims will turn in ac
cordance with the turning ‘of the shaft at said ?rst and
second lines, respectively, a stator adjacent the toothed
rims, drive means connected to the stator for turning the
stator about the shaft axis while the shaft is stationary,
means connected to the stator for preventing it from
rotating when \a measurement is to be made, magnetic
means in the stator for co-operating with the teeth for
the generation of alternating current when the shaft turns,
the ?rst and second support members, respectively, and
slip rings and cooperating brushes for conveying from
ing two further magnet systems ?xed on the stator and
each having a pole shoe, one shoe being presented to the
teeth of one rim and the other pole to the teeth of the
other rim.
5. A pick-up for torque measuring apparatus, compris
ing a shaft, ?rst and second juxtaposed toothed rims in
spaced relation co-axial with the shaft whereof the teeth
are of equal pitch and are of magnetic vmaterial, ?rst and
second cylindrical support members surrounding the shaft
the stator alternating currents generated in the magnetic
making substantial line contact with the shaft around
means thereof, and bearings engaging the stator and one
?rst and second spaced peripheral lines on the shaft,
of the support members at spaced locations distributed
whereby the ?rst and second rims will turn in accordance
with the turning of the shaft at said ?rst and second lines, 40 around the entire circumference of said one support
member and supporting the stator in- space and locating
respectively, a stator adjacent the toothed rims, a ?xed
it ‘both axially and radially with respect to said one sup
abutment member adjacent to the stator, spring means
port member.
effective between said abutment member ‘and the stator for
urging the stator towards the toothed rims, means con
nected to the stator for preventing it from rotating when
a measurement is to .be made, magnetic means in the
stator for co-operating with the teeth for the generation
of alternating current when the shaft turns, and bearings
engaging the stator and one of the support members at
spaced locations distributed around the entire circum
ference of said one support member and supporting the
stator in space and locating it both vaxially and radially
with respect ‘to said one support member.
6. A pick-up according to claim 5, wherein the spring
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,217,539
2,270,760
2,365,564
2,579,629
De Bruin ______________ __ Oct. 8,
Mershon ____________ __ Jan. 20,
L-anger ______________ __ Dec. 19,
Tubbs ______________ __ Dec. 25,
2,675,700
2,754,683
2,766,617
Van Degrift et a1 _______ _- Apr. 20, 1954
Waugh ______________ __ July 17, 1956
Tyler et al. __________ __ Oct. 16, 1956
763,063
Great Britain __________ __ Dec. 5, 1956
means urge the stator as aforesaid in both the axial and
the radial directions.
FOREIGN PATENTS
1940
1942
1944
1951
,
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