Abstrict A pulse transmitter for a liquid flow meter comprises an input
shaft rotatably mounted in a housing and magnetically coupled through
a wall of the housing to a rotor of the meter. A meanetic reed switch
for electrical current interrupt is operated by a rotating magnetic
member on an output shaft, the output shaft being connected to the
input shaft by a pair of calibration gears. The input shaft has
a pinion thereon, the transmitter including provisions for compound
reduction gearing to a sleeve on the input shaft, the sleeve driving
one of the calibration gears. The input shaft also has an upper
magnetic coupling member for driving a visible indicator ball through
a wall of the housing, the ball being confined in an external cavity
by a transparent member.
Claims What is claimed is:
1. Apparatus for generating pulses corresponding to the rotation
of a rotating member, the apparatus comprising:
(a) a rotatably mounted input shaft;
(b) means on the input shaft for coupling the input shaft to the
rotating member;
(c) an output shaft;
(d) means for repetitively interrupting an electrical current in
response to rotation of the output shaft;
(e) sleeve means on and concentric with the input shaft;
(f) calibration gear means for rotating the output shaft in response
to rotation of the sleeve means; and
(g) range means for rotating the sleeve means at a predetermined
turns ratio relative to the input shaft, comprising:
(i) auxiliary support means for rotatably mounting a compound shaft
and gearing the compound shaft to the input shaft and to the sleeve
means;
(ii) a first range member operatively connected between the input
shaft and the sleeve means, whereby the turns ratio is a first turns
ratio; and
(iii) means for disconnecting the first range member and receiving
and connecting a second range member between the input shaft and
the sleeve means at a second turns ratio without disturbing the
mounting of the input shaft during the disconnecting of the first
range member and the receiving and connecting of the second range
member.
2. The apparatus of claim 1 wherein the range means further comprises:
(a) pinion means on the input shaft;
(b) a support member mounted to the auxiliary support means; and
(c) a compound shaft rotatably mounted to the support member and
geared to the pinion means and to the sleeve means.
3. The apparatus of claim 2 wherein the range means further comprises
change gear means for connecting the compound shaft to the sleeve
means, the change gear means being mounted so that removal and replacement
thereof does not require the mounting of either one of the compound
shaft or the input shaft to be disturbed.
4. The apparatus of claim 1 wherein the calibration gear means
includes a drive gear, the drive gear being rotationally fixed to
the sleeve means, and an output gear rotationally fixed to the output
shaft, the apparatus further comprising means for replacing the
drive gear and the output gear without disturbing the mounting of
either the input shaft or the output shaft during the replacement
of the drive wear and the output gear.
5. The apparatus of claim 1 wherein the range means further comprises
coupling means for directly connecting the sleeve means to the input
shaft and releasing the sleeve means from the input shaft, without
disturbing the mounting of the input shaft during the connecting
and releasing of the coupling means.
6. The apparatus of claim 1 wherein range means comprises pinion
means fixed to the input shaft, and the auxiliary support means
comprises:
(a) a journal in the housing for rotatably receiving a first end
of the compound shaft; and
(b) a supportive surface fixed within the housing and having engaged
means for engaging at least one fastener for mounting a support
member for the compound shaft.
7. The apparatus of claim 6 wherein the range means further comprises:
(a) a support member mounted to the supportive surface and fixed
thereto by a fastener, the fastener engaging the engaging means;
and
(b) a compound shaft rotatably mounted to the support member and
geared to the pinion means and to the sleeve means, a first end
of the compound shaft rotatably engaging the journal.
8. Apparatus for generating pulses corresponding to the rotation
of a rotating member, the apparatus comprising:
(a) a housing, the housing being adapted for mounting proximate
the rotating member;
(b) an input shaft rotatably mounted and enclosed within the housing
and having a first magnetic member thereon for coupling the input
shaft to the rotating member;
(c) pinion means fixed to the input shaft;
(d) auxiliary support means for rotatably mounting a compound shaft
and gearing the compound shaft to the pinion, without disturbing
the mounting of the input shaft and without requiring the first
magnetic member to be decoupled from the rotating member during
the mounting and gearing of the compound shaft to the pinion;
(e) an output shaft;
(f) means for repetitively interrupting an electrical current in
response to rotation of the output shaft;
(g) sleeve means on the input shaft;
(h) calibration gear means for coupling the output shaft to the
sleeve means at a calibration ratio;
(i) means for receiving and connecting coupling means whereby the
sleeve means is prevented from rotating relative to the input shaft,
the calibration ratio defining a first overall gear ratio between
the input shaft and the output shaft, without disturbing the mounting
of the input shaft and without requiring the first magnetic member
to be decoupled from the rotating member during the receiving and
connecting of the coupling means; and
(j) means for receiving and connecting change gear means for gearing
the sleeve means to the compound shaft, whereby a second overall
gear ratio between the input shaft and the output shaft is defined
by the product of a compound ratio from the input shaft to the sleeve
means through the compound shaft, and the calibration ratio, without
disturbing the mounting of the input shaft and without requiring
the first magnetic member to be decoupled from the rotating member
during the receiving and connecting of the change gear means.
9. The apparatus of claim 8 further comprising a support member
removably mounted to the auxiliary support means and having a compound
shaft rotatably mounted thereto, the compound shaft being geared
to the pinion means of the input shaft, and wherein the sleeve means
is geared to the compound shaft.
10. The apparatus of claim 8 wherein the calibration gear forming
the sleeve means and means includes a drive gear, the drive gear
being rotationally fixed to the input shaft.
11. The apparatus of claim 8 wherein the means for producing electrical
pulses comprising:
(a) an output magnetic member fixed to the output shaft; and
(b) a magnetically operated switch device coupled to the output
magnetic member.
12. The apparatus of claim 8 further comprising:
(a) an indicator magnetic member rotatably coupled to the input
shaft;
(b) an indicator cavity in the housing, the indicator cavity being
visible external to the housing; and
(c) an indicator device movable in the indicator cavity, the indicator
device being magnetically coupled to the indicator magnetic member
for displaying rotational movement of the input shaft.
13. The apparatus of claim 12 wherein the indicator device comprises
a spherical member rollable about the periphery of the cavity.
14. The apparatus of claim 8 wherein the housing comprises a lid
member for providing access to the auxiliary support means, the
sleeve means and the calibration gear means, the lid member being
sealingly connected to a main portion of the housing and removable
while the input shaft remains operationally coupled to the rotating
member and the interrupting means remains operationally connected
to the input shaft, without disturbing the mounting of either the
input shaft or the output shaft during removal of the lid member.
15. The method for changing a range scale factor of an apparatus
for generating pulses corresponding to the rotation of a rotating
member, the apparatus comprising a rotatably mounted input shaft,
means on the input shaft for coupling the input shaft to the rotating
member, an output shaft, means for repetitively interrupting an
electrical current in response to rotation of the output shaft,
sleeve means on and concentric with the input shaft, calibration
gear means for rotating the output shaft in response to rotation
of the sleeve means, and range means for rotating the sleeve means
at a first turns ratio with respect to the input shaft, the method
comprising the steps of:
(a) releasing the range means without disturbing the mounting of
the input shaft; and
(b) gearing the sleeve means at a second turns ratio with respect
to the input shaft without disturbing the mounting of the input
shaft.
16. The method of claim 15 further comprising the step of clamping
the sleeve to the input shaft.
17. The method of claim 15 further comprising the steps of:
(a) providing a compound shaft, the compound shaft having a driven
gear fixed thereto;
(b) rotatably supporting, without disturbing the mounting of the
input shaft, the compound shaft in the housing with the driven gear
in geared engagement with the input shaft;
(c) fixing a first change gear to the compound shaft; and
(d) engaging a second change gear with the sleeve, the second change
gear being in mesh with the first change gear.
18. Apparatus for generating pulses corresponding to the rotation
of a rotating member, the apparatus comprising:
(a) a rotatably mounted input shaft;
(b) means on the input shaft for coupling the input shaft to the
rotating member;
(c) means for repetitively interrupting an electrical current in
response to rotation of the input shaft;
(d) housing means for excluding moisture from the input shaft and
the interrupting means;
(e) a magnetic member rotatably mounted in the housing;
(f) means for rotating the magnetic member in response to rotation
of the input shaft;
(g) a cavity in the housing means external to the input shaft,
the interrupting means, and magnetic member, the cavity having a
circular periphery aligned concentrically with the magnetic member;
(h) a spherical member rollable about the periphery of the cavity
and magnetically coupled to the magnetic member; and
(i) window means for retaining the indicating means in the cavity,
whereby the spherical member rolls about the periphery of the cavity
in response to rotation of the input shaft.
19. The apparatus of claim 18 wherein the magnetic member is fixed
to the input shaft.
Description BACKGROUND
The present invention relates to fluid flow meters, and more particularly
to a pulse transmitter for a positive element or rotating-element
flow meter.
A conventional class of flow meters has a rotatable component such
as a spindle connected to a nutating disk. Traditionally, such meters
are equipped with mechanical counters or totalizers for indicating
a cumulative volume which is periodically read and recorded. In
industrial process applications such as mixing batches of concrete,
it is desired to continuously monitor and control the flow in order
to maintain a correct mixture. Thus the meter is equipped with a
transmitting device that is monitored by a computer, pulse counter
or the like in an electronic control system. Rotation of the element,
coupled magnetically through a wall of the meter, is transferred
to an input shaft of a pulse transmitter that is fastened to the
meter. The pulse transmitter is typically equipped with reduction
gears for providing a calibration range and interchangeable calibration
gears for making small-scale changes in the quantity of fluid metered
per pulse.
The conventional pulse transmitters have one or more of the following
disadvantages:
1. They are unreliable because of the excessive drag caused by
a large number or range and calibration gearing elements, particularly
where unity reduction or step-up gearing is required;
2. They are unreliable because of magnetic interference between
the magnetic coupling and a magnetically operated switch used as
the transmitting device;
3. They are expensive to produce in that a large number of transmitters
having separate calibration ranges must be inventoried because the
calibration gears provide a limited calibration range for each transmitter;
4. They are difficult to monitor in operation because the moving
parts are not visible; and
5. Field modification of the range of calibration is impractical
because difficult dissassembly and reassembly of the transmitter
is required.
Thus there is a need for a pulsed flow transducer that has low
rotational drag at unity reduction ratio, a large range of field-changeable
calibration, and is reliable, easy to monitor, and inexpensive to
produce.
SUMMARY
The pulse transducer of the present invention meets this need by
incorporating a unique convertible combination of direct drive,
reduction gearing and calibration gearing to a pulse device. The
transducer includes a rotationally mounted input shaft having input
coupling means, an output shaft coupled to current interrupt means,
calibration gear means for connecting the output shaft to sleeve
means on the input shaft, and range means for driving the sleeve
means from the input shaft at a predetermined turns ratio.
Preferably the transducer includes means for mounting a compound
shaft in geared relation to the input shaft without disturbing the
mounting of the input shaft, the calibration gear means being capable
of being driven by the compound shaft.
An important feature of the present invention is that the compound
shaft, being installable without disturbing the mounting of the
input shaft, facilitates field modification of the transmitter to
different ranges of calibration.
Another feature of the present invention is that a range turns
ratio of one-to-one is achieved by direct drive of the calibration
gears from the input shaft. Thus the complexity and added drag of
the compound shaft may be avoided when the one-to-one range ratio
is implemented.
Preferably the transducer includes a housing, indicating means
movable in a cavity of the housing and retained by window means,
and a magnetic member on the input shaft for coupling rotation of
the input shaft to the indicating means.
In a preferred version, the transmitter includes a housing, an
input shaft in the housing having a pinion and a first magnetic
member coupling the input shaft to an external rotating member,
support means for a compound shaft geared to the pinion, current
interrupt means responsive to rotation of an output shaft, and calibration
gear means for coupling the output shaft to the input shaft. A drive
gear of the calibration gear means may be fixed to the input shaft
for providing a range turns ratio of unity. Alternatively, the calibration
gear means is geared to the compound shaft.
Preferably the current interrupt means includes a magnetically
operated switch coupled to an output magnetic member on the output
shaft. Preferably the input and output magnetic members have axially
concentrated magnetic fields facing apart, the output magnetic member
being located between the switch and the input magnetic member for
preventing magnetic interference between the magnetic members and
the switch.
The present invention provides a method for generating electrical
pulses corresponding to rotation of a rotating member, the method
including the steps of:
(a) rotatably mounting an input shaft in axial alignment with the
rotating member;
(b) coupling the input shaft to the rotating member for rotating
the input shaft in unison with the rotating member;
(c) mounting a pinion gear on the input shaft;
(d) providing a sleeve on the input shaft, the sleeve rotating
in response to rotation of the input shaft;
(e) gearing an output shaft to the sleeve;
(f) providing means for mounting a compound shaft geared to the
pinion and to the sleeve; and
(g) interrupting an electrical current by operating switch means
from the output shaft.
Preferably the method includes the further steps of:
(a) providing a compound shaft, the compound shaft having a driven
gear fixed thereto;
(b) inserting, without disturbing the mounting of the input shaft,
the compound shaft into the mounting means with the driven gear
in mesh with the pinion;
(c) affixing a first change gear to the compound shaft;
(d) engaging a second change gear with the sleeve, the second change
gear being in mesh with the first change gear.
DRAWINGS
These and other features, aspects, and advantages of the present
invention will become better understood with reference to the following
description, appended claims, and accompanying drawings where:
FIG. 1 is a fragmentary plan view of a pulse transmitter according
to the present invention;
FIG. 2 is a fragmentary sectional elevational view of the transmitter
of FIG. 1 taken on line 2--2 in FIG. 1;
FIG. 3 is a fragmentary sectional elevational view of the transmitter
of FIG. 1 taken on line 3--3 in FIG. 1;
FIG. 4 is a fragmentary sectional elevational view of an alternative
configuration of the transmitter of FIG. 1 within region 4 in FIG.
3;
FIG. 5 is a fragmentary plan sectional detail view taken on line
5--5 in FIG. 4; and
FIG. 6 is a schematic diagram of the transmitter of FIG. 1.
DESCRIPTION
The present invention is directed to a pulse transmitter for a
rotational or positive displacement fluid flow meter. With reference
to FIGS. 1-3 a transmitter unit 10 according to the present invention
is attached to a meter 12 the transmitter unit 10 having a housing
14. The housing 14 has a body 16 and a cover 18 the body 16 having
a bayonet mount 20 for engaging the meter assembly 12. A base screw
21 secures the housing 14 to the meter assembly in a selected orientation.
The meter assembly 12 includes a magnetic rotor 22 coupled to a
measuring element therein (not shown), the rotor 22 being located
proximate to a wall portion or coupling partition 24 of the body
16.
A gear plate assembly 26 having an upper plate 28 and a lower plate
30 is mounted inside the housing 14 the lower plate 30 being fastened
to the body 16 by at least one mounting screw 32. The upper plate
28 and the lower plate 30 are held in separated parallel alignment
by a plurality of standoffs 34. The upper plate 28 and the lower
plate 30 are fastened to the standoffs 34 by corresponding plate
screws 36 and 38.
A vertically disposed input shaft 40 is rotatably mounted to the
plate assembly 26 on a pair of flanged bushings 42 and 44 the input
shaft 40 having a magnetic member or input coupling 46 fixed thereon
proximate the coupling partition 24 and aligned with the rotor 22
of the meter assembly 12. Thus the input shaft 40 rotates in unison
with the rotor 22 the housing 14 (including the coupling partition
24) being of a non-magnetic material for freely permitting passage
of a rotating magnetic field. The input coupling 46 has an axially
concentrated magnetic field, the flux of which is directed substantially
exclusively downwardly toward the rotor 22 for preventing magnetic
interference in the transmitter unit 10 as further described herein.
A centrally located thrust member or button 48 is fixed to the
bottom of the input coupling 46. The button 48 comprising a low-friction,
self-lubricating material such as an acetal resin, rests against
the coupling partition 24 for defining a vertical position of the
input coupling 46 and for limiting rotational drag on the input
shaft 40.
An output shaft 50 is rotatably mounted on a pair of bushings 52
and 54 to one side of the input shaft 40 and is connected thereto
by a pair of calibration gears 56 and 58. The gears 56 and 58 are
clamped to the output shaft 50 and the input shaft 40 by respective
set screws 60 and 62. The output shaft 50 has a magnetic member
or output coupling 64 fixed thereon for actuating a magnetic reed
switch 66. The output coupling 64 has an axially concentrated magnetic
field, the flux of which is directed substantially exclusively upwardly
toward the switch 66 for preventing magnetic interference between
the input coupling 46 and the output coupling 64. The output coupling
64 is located between the switch 66 and the input coupling 46 the
respective fields facing apart. Consequently, magnetic interference
with proper operation of the switch 66 is prevented by the downwardly
facing flux of the input coupling 46 described above, and the oppositely
facing flux of the output coupling 64 effectively shielding the
switch 66 from the rotor 22 and the input coupling 46.
The switch 66 has a pair of leads 68 and 70 each clamped with
a respective wire 72 and 74 by a corresponding terminal clamp 76
and 78 on the upper plate 28. The upper plate 28 is formed of an
electrically non-conductive material such as phenolic for isolating
the leads 68 and 70 from the housing 14. The switch 66 is located
in a slot 75 in the upper plate 28 for conveniently aligning the
switch 66 proximate to the output coupling 64. Rotational orientation
of the switch 66 on its axis is not critical; thus the switch 66
may be installed by dropping it in the slot 75 with the leads 68
and 70 engaging the clamps 76 and 78 then tightening the clamps
76 and 78.
The wires 72 and 74 permit the switch 66 to be connected in an
electrical circuit (not shown) for producing pulses corresponding
to the rotation of the output shaft 50 by interrupting electric
current in the circuit in a conventional manner. The wires 72 and
74 together with a ground wire 80 that is connected to the body
16 by the mounting screw 32 are brought out of the housing 14 through
a fitting 82 the fitting 82 being threaded into the body 16. Moisture
is excluded from the housing 14 by a barrier 84 of potting compound,
epoxy or the like, formed around the wires 72 74 and 80 in the
fitting 18. Moisture is further excluded from the housing 14 by
an O-ring seal 86 between a flange 88 of the cover 18 and a bore
90 of the body 16 the cover 18 being clamped in position by a cover
screw 92.
The cover 18 is provided with an annular cavity 152 on the outside
thereof in line with the input shaft 40. A magnetically permeable
ball 154 is free to roll within the cavity 152 for indicating movement
of the input shaft 40. A magnetic indicator coupling 156 is fastened
to the top of the input shaft 40 by a set screw 158 for coupling
movement of the input shaft 40 to the ball 154. Thus when rotation
of the rotor 22 produces a corresponding rotation of the input shaft
40 the ball 154 moves in unison with the rotor 22. A transparent
window 160 is fastened to the cover 18 by a window screw 162 the
window retaining the ball 154 in the cavity 152. The indicator coupling
156 has an axially concentrated magnetic field, the flux of which
is directed substantially exclusively upwardly away from the switch
66 and toward the ball 154 for preventing magnetic interference
between the indicator coupling 156 and the switch 66.
The movement of the ball 154 is useful for verifying that the rotor
22 is moving and that the motion is being coupled into the transmitter
unit 10. It has also been determined that observation of the ball
152 in motion greatly facilitates calibration of the meter assembly
12 in its process application. In fact, observation of the ball
154 is more effective in calibration than observation of a traditional
totalizer indicator.
The purpose of the calibration gears 56 and 58 is to permit ratio
changes between the input shaft and the output shaft for generating
electrical pulses at desired metered volume intervals. There is
a practical limit, however, in the range of possible ratios. The
maximum step-down or step-up ratio is limited firstly by the required
minimum gear size compatible with the respective shafts 40 and 50
and corresponding clearance about the other shaft. The maximum step-up
ratio is also limited secondly by a maximum resultant drag that
is reflected to the rotor 22. A third limitation is that a combination
of a very large gear in mesh with a small gear is subject to binding
between mating teeth unless unduly expensive manufacturing techniques
are utilized. Thus a maximum step-up or step-down ratio of approximately
3:1 is possible or, conservatively, 2:1 with molded gears on metallic
hubs that are easily interchangable.
Further gearing is needed, however, for covering typical pulse
rate requirements ranging from about eight pulses per revolution
of the rotor 22 down to about one pulse per forty revolutions of
the rotor 22. The range of required ratios is 80:1 even if the
output coupling 64 is appropriately selected to have either four
magnetic poles or one, giving rise to a corresponding number of
pulses per revolution of the output shaft 50. For example, a step-up
ratio of 2:1 between the input shaft 40 and the output shaft 50
produces eight pulses per revolution of the rotor 22 when the output
coupling 64 has four magnetic poles. Also, a step down ratio of
2:1 between the input shaft 40 and the output shaft 50 produces
one pulse in forty revolutions of the input shaft 40 using a single
magnetic pole output coupling 64 only if an additional 20:1 reduction
is applied between the input shaft 40 and the gear 58. For simplicity,
the following discussion is limited to the presence of four magnetic
poles in the output coupling 64.
The reflected drag is not excessive at a 2:1 step-up as long as
the gear 58 is directly connected to the input coupling 46; however,
difficulty with excessive drag may be encountered at a step-up ratio
greater than approximately 1.6:1 when additional gearing is introduced
between the input coupling 46 and the gear 58.
The present invention permits direct connection of the gear 58
to the input shaft 40 as described above, as well as connection
through a compound reduction as described herein. Field modifications
between these configurations are possible without requiring complicated
disassembly or removal of the gear plate assembly 26 from the housing
14 or disturbing the rotational mounting or alignment of either
the input shaft 40 or the output shaft 50.
As shown in FIGS. 1 and 3 the lower plate 30 incorporates a flanged
bushing 94 for receiving a compound shaft 96 described below. The
upper plate 28 is formed with an opening 98 for passing a driven
gear 100 described below, a pair of threaded mounting holes 102
being formed in the upper plate 28 on opposite sides of the opening
98. Additionally, the input shaft has a pinion 104 fixed thereto
between the plates 28 and 30 for driving the driven gear 100.
With further reference to FIGS. 4 and 5 when it is desired to
incorporate a gear reduction between the input shaft 40 and the
gear 58 the gear 58 is replaced by a sleeve 106 a driven gear
108 and a calibration gear 110 the gear 110 functioning in place
of the gear 58. The gear 56 is inverted as shown for properly engaging
the gear 110. The sleeve 106 turns freely on the input shaft 40
but the gears 108 and 110 are rotationally locked together by engaging
a non-circular portion of the sleeve 106. As shown in FIG. 5 a
shank portion 112 of the sleeve 106 is of square cross-section for
rotationally locking thereto the gears 108 and 110. The shank portion
112 is concentric with the input shaft 40 for maintaining alignment
of the gears 108 and 110. As shown in FIG. 4 a spacer 159 is located
on the input shaft 40 between the indicator coupling and the gear
110 for retaining the gear 110 on the spacer 106.
The input shaft 40 is rotationally coupled to the gear 110 by means
of the driven gear 100 fixed to the compound shaft 96 as shown
in FIG. 4 the compound shaft 96 being rotationally mounted on the
bushing 94 and an additional bushing 114 in an auxiliary plate 116
the plate 116 being fastened to the upper plate 28 by a pair of
screws 118. A drive gear 120 fastened to the compound shaft 96
by a set screw 122 engages the driven gear 108 that is locked to
the gear 110 as described above. The compound shaft 96 together
with the driven gear 100 is lowered through the opening 98 by tipping
the shaft 96 outwardly away from the input shaft 40 until the gear
100 passes through the opening 98. Thus the opening 98 need not
be fully as large in diameter as the gear 100 for permitting assembly
of the shaft 96 with the gear 100 without separating the upper plate
28 or the lower plate 30 from the standoffs 34.
As shown in FIG. 5 the gear 110 and the sleeve 106 may be fixed
directly on the input shaft 40 by substituting a collar 124 for
the gear 108 a set screw 126 engaging the collar 124 and extending
through the sleeve 106 against the input shaft 40.
With further reference to FIG. 6 block 130 represents the calibration
gear ratio between the input shaft 40 (or sleeve 106) and the output
shaft 50 produced by the gears 56 and 58 (110). When the gear 58
is used, a hub 59 thereof functions as a sleeve directly coupled
to the input shaft by the set screw 62. In the block 130 m represents
the number of revolutions of the input shaft 40 (sleeve 106) during
a corresponding number n of revolutions of the output shaft 50.
Thus m/n is a reduction or step-down ratio between the input shaft
40 (sleeve 106) and the output shaft 50.
Similarly, block 132 represents a reduction ratio between the input
shaft 40 and the compound shaft 96 if present. The numeral 4 and
the phantom numeral 1 indicate a reduction or step-down ratio of
4:1 such as produced by the pinion 104 having 11 teeth and the
gear 100 having 44 teeth. Block 134 represents a gear ratio between
the compound shaft 96 and the sleeve 106 the phantom letters x
and y representing the number of corresponding revolutions of the
respective compound shaft 96 and sleeve 106. Thus x/y is the step-down
ratio between the shaft 96 and the sleeve 106. It should be understood
that when either m/n or x/y are less than unity, a step-up ratio
that is the inverse of the respective fraction is indicated.
In the following tables are given a number of possible gear combinations
in a preferred implementation of the present invention. In the tables,
"Vol." represents the number of revolutions of the input
shaft 40 (and the rotor 22) that is required to produce one opening
and closing of the switch 66.
TABLE 1 ______________________________________ Vol. m n m/n x y
x/y 4x/y ______________________________________ 0.1136 20 44 0.455
-- -- -- -- 0.125 19 38 0.500 -- -- -- -- 0.226 19 21 0.905 -- --
-- -- 0.250 28 28 1.000 -- -- -- -- 0.452 38 21 1.810 -- -- -- --
0.500 38 19 2.000 -- -- -- -- 0.500 28 28 1.000 19 38 0.500 2.000
0.678 19 21 0.905 24 32 0.750 3.000 0.750 28 28 1.000 24 32 0.750
3.000 0.905 19 21 0.905 27 27 1.000 4.000 1.000 28 28 1.000 27 27
1.000 4.000 1.131 19 21 0.905 30 24 1.250 5.000 1.200 28 28 1.000
30 24 1.250 5.000 1.357 19 21 0.905 30 20 1.500 6.000 1.500 28 28
1.000 30 20 1.500 6.000 1.809 19 21 0.905 38 19 2.000 8.000 2.000
28 28 1.000 38 19 2.000 8.000 2.262 38 21 1.810 30 24 1.250 5.000
2.500 38 19 2.000 30 24 1.250 5.000 2.714 38 21 1.810 30 20 1.500
6.000 3.000 38 19 2.000 30 20 1.500 6.000 3.619 19 21 0.905 44 11
4.000 16.00 4.000 28 28 1.000 44 11 4.000 16.00 7.238 38 21 1.810
44 11 4.000 16.00 8.000 38 19 2.000 44 11 4.000 16.00 ______________________________________
TABLE 2 ______________________________________ Vol. m n m/n x y
Nom V. Change ______________________________________ 0.1111 20 45
0.444 -- -- 0.1136 -2.22% 0.1163 20 43 0.465 -- -- 0.1136 +2.32%
0.1218 19 39 0.487 -- -- 0.125 -2.56% 0.1284 19 37 0.514 -- -- 0.125
+2.70% 0.220 29 33 0.879 -- -- 0.226 -3.00% 0.233 28 30 0.933 --
-- 0.226 +3.15% 0.242 32 33 0.970 -- -- 0.250 -3.10% 0.258 33 32
1.031 -- -- 0.250 +3.10% 0.440 37 21 1.762 -- -- 0.452 -2.70% 0.464
39 21 1.857 -- -- 0.452 +2.63% 0.485 32 33 0.970 19 38 0.500 -3.10%
0.486 37 19 1.947 -- -- 0.500 -2.70% 0.513 39 19 2.053 -- -- 0.500
+2.56% 0.515 33 32 1.031 19 38 0.500 +3.10% 0.659 29 33 0.789 24
32 0.678 -3.00% 0.700 28 30 0.933 24 32 0.678 +3.15% 0.727 32 33
0.970 24 32 0.750 -3.10% 0.773 33 32 1.031 24 32 0.750 +3.10% 0.879
29 33 0.879 27 27 0.905 -3.00% 0.933 28 30 0.933 27 27 0.905 +3.00%
0.970 32 33 0.970 27 27 1.000 -3.10% 1.031 33 32 1.031 27 27 1.000
+3.10% 1.098 29 33 0.878 30 24 1.131 -3.00% 1.166 28 30 0.933 30
24 1.131 +3.00% 2.434 37 19 1.947 30 24 1.250 -2.70% 2.566 39 19
2.053 30 24 1.250 +2.56% ______________________________________
Table 1 lists a number of "nominal" volumes that correspond
to useful engineering units when the transmitter unit 10 is used
with commercially available meters. Table 2 shows how the calibration
gears 56 and 58 (or 110) may be used to raise or lower the nominal
volumes on the order of three percent. Thus Nom. V. in Table 2 is
a corresponding Vol. from Table 1.
The transmitter unit 10 of the present invention is unencumbered
with complicated drag-producing gearing between the input coupling
46 and the calibration gear 58 unless a significant reduction ratio
is required, in which case gearing drag is not a serious factor
in reliable operation.
Additionally, the transmitter unit 10 is inexpensive to produce
in that a large number of transmitters having separate calibration
ranges need not be inventoried because an unlimited number of the
available gear combinations may easily be incorporated without requiring
complicated disassembly of the unit. Moreover, field modification
of the range of calibration is quite practical because difficult
dissassembly and reassembly of the transmitter is not involved.
In particular, a kit for implementing range gearing from the pinion
104 of the transmitter unit 10 includes the compound shaft 96 having
the driven gear 100 the auxiliary plate 116 having the bushing
114 a pair of the screws 118 the collar 106 and at least one
each of the gears 108 110 and 120.
Moreover, the transmitter unit 10 is easy to visually monitor in
operation by means of the indicating ball 154 that moves in unison
with the rotor 22.
Although the present invention has been described in considerable
detail with reference to certain preferred versions thereof, other
versions are possible. For example, the auxiliary plate 116 can
provide complete rotational support for the compound shaft 96 substituting
for the bushing 94. Also, the pinion 104 can be removably clamped
to the input shaft 40 above the upper plate 28. Therefore, the spirit
and scope of the appended claims should not necessarily be limited
to the description of the preferred versions contained herein. |