Note: Descriptions are shown in the official language in which they were submitted.
~Q3~
B k~ound of the Inveneion
In high speed operation of rotating parts, lt is
necessary to maintain such parts at a rate of rotation which
pr~vides for reliable and efflcient results in accordan~e with
predetermined levels. In the field of printing, or example,
when the printing is acc~mpllshed by means of i~pact mechani~m
striking a character bearing member of the rotating type~ such
member must be rapidly moved into posl~ion for each and every
character thereon to be struck by the lmpact mechanism. The
character bearing member may9 for example, be in ~he form of a
drum or typewheel which is driven by a mo~or, the speed of such
motor being maintained to make certain that the drum or type-
wheel i8 in ~he proper posltion at ehe instant that the impace
mech~nism is dr'.ven agalnst the selected character thereon for
printing of such character. It is, therefore~ necessary that
~, the speed oi the motor driver for the character bearing member
be ad~usted so that such member cAn be positioned suficiently
fast to avoid printing a character too late in the cycle, while
. at the ~ame time ~eeing that the motor 18 not driven faster
than its rated speèd. Of cour~e~ the mo~or speed control
system should include provision for ad~u~t~ng the spe d of the
motor so as to obtain a ~peclfied number of bearing member
character positions in a predetermined time to meet the require~
ments of the operation.
A number of ways and means for controlllng motor
speeds have lncluded both simple and complex system~. Repre~
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., , . , : , .
3416
sentative of control systems in the prior ar~ is Uni~ed States
Patent No. 2,706,270, issued on April 129 1955 ~o F, G. S~eele9
which dlscloses a digital control system including a palr of -~
pul3e carrying channels for controlling ~he setting of a pair
o reversing switches connected to rotate the armature of a
motor~ on the occurrence of each clock pulse, in the direction
dictated by the informstion. Vnited Stat~s Patent No. 3,237,17
issued on February 22, 1966 to A.G. Valentine, discloses control
appar~tus for a closed loop system having a phase detector, a
reversible counter, flip-flop means or computer means, and a
digital to analog converter or voltage switch means. Indicating
means in the form of a voltmeter is connected to receive an
analog output signal from the voltage switch means. Unlted
States Patent No. 39586,953, issued on June 22, 1971 to C. O.
Markkanen et al., shows a stepper motor control system includ-
ing an encoder which develops a coded signal representative of
a plurality of sh~aft positions on either side o~ a reference
position. Coded s ign~ls representative of ~he desired position
of~the motor and shaft poSitiDn signals are applied to a com-
parator and logic circuit which develops output pulses to bringthe coded signals and the position signals into coincidence.
~` Another United States Paten~ No. 3,648,141, issued on March 7,
1972 to D. W, Scheer, shows a tape drive error-canceling system
having a speed control circuit using comparator means for c~m- -
paring a capstan speed responsive varlable frequency signal
with a reference frequency proportional to a desired capstan
.. .
3~
speed. A memory stores a separ~te speed correction signal for
each of the capstan angular positlons. The memory information
is read concurrently with a sensing of each position and applied -
~with the outpu~ signal from the comparator means to motor
energizing means to control the capstan speed. United States
Patent No. 3,659,524, issued on May ~9 1972 to J. Beery et al.,
shows a printer control system including first drive means
operated at one speed and second drive means operated at a
slower speed~ with means for detecting the presence of a docu
ment. The control means also synchronize~ the operation of the
prin~ hammer, the print wheel and document movement responsive
to speed of the document. And, Unit:ed States Patent No.
3,838,258, issued on September 24, 1974 to D. J~ Logan, dis-
closes a control system for a step motor which includes a
computer to control the energization of the motor in response
to information supplied thereto. Motor increments are produced
by~the computer program without the aid of an external clock or
feedback signals from the motor. The computer program includes
one wait loop following each change in the output word to pro- ~;
vide a predetermined delay preceding the nex~ word change ~nd
to control the motor velocity.
Summary of the Inventlon
~,
The present invention xelates to method and apparstus
for ad~usting the speed o~ a prime mover in the nature of a
stepping motor and more particularly to the providing of a
control system which utilizes a microprocessor
: .. .. " . ,
having clock pulse and processor memory capability for gener-
ating timing signals designated as reference and speed en
velopes. In accordance with the present invention, there is ~ ;
provided a method of controlling the speed of a prime mover
comprising the steps of generating a programmed re-ference
signal of predetermined time duration, generating a speed
signal indicative of the actual speed of the prime mover in
successive relationship with said reference signal, repeating `~
said reference signal in duplicating manner for a desired
number of times, repeating said speed signal in alternate -
relationship with said reference signal for said number of
times, utilizing programmed memory for tracking the number
of repeated speed signals and reference signals, synchronizing
said reference signals and said speed signals by clocking
predetermined time periods therewith, setting the programmed
memory to indic~te mode index of the prime mover, observing
diferences in time periods between said reference signals
and said speed signals, and adjusting the width of said
speed signals to equal the width of said reference signals.
Additionally, the present invention provides a control system
for adjusting the speed of a prime mover to conform with
predetermined parameters, including means for generating ~.
reference signals of fixed time duration, memory means asso-
ciated with said reference signal generating means for reading
the number of cycles of fixed time duration of said reference
:;
signals, means for generating signals indicative of the speed
of said prime mover in alternate relationship with said
reference signals, means indicating differences in time
duration between said reference signals and said speed sig-
nals, and means for adjusting the width of said speed signals
to correspond with the width of said reference signals. Upon
., .,. .. - .; . .
~ /;39!~6
starting rotation by the first phase switching of the prime
mover, a one-shot multivibrator, hereinafter referred to as
speed one-shot and associated with the prime mover, is trigger-
ed so as to generate two pulses for each character step of
rotation of the character bearing member, with subsequent phase :~
switchings of the prime mover occurring on the falling edge of
each of the speed one~shot pulses, with the resultant obser-
vation that the width of such speed one-shot pulses affects
the times of phase switching and the speed of rotation of the
motor~ Tbe leading edge of a particular speed one-shot pulse
triggers a further one-shot multivibrator, hereinafter
referred to as delay one-shot and associated with the micro-
processor, and the final phase switc.hing of such prime mover
occurs on the falling edge of this further one-shot pulse.
A first signal or speed envelope in the nature of a voltage
pulse is produced at a test point wit:h such signal beginning ~:
at the first phase switching of the prime mover and ending
at the triggering of the delay one-shot~
For a seven character sequence of stepping motion,
the width of the first signal or speed envelope is a predeter-
mined duration of time, and means for adjusting the speed one~
shot is desirable for achieving the correct relationship of
pulsewidth-time duration. At regular intervals of repeated
seven character sequence cycles, an indicating means in the
-5a- :-
~,"
.
39~
nature of a moving needle meter is connected for indlcating a
voltage reading which is proportional to the width of the
speed envelope, ~uring alternate time int~rvals of approximate- ~ :
ly one second, the stepping motor is mo~ed through the seven
character sequence twenty times, with each ~even character
stepping sequence being ~ynchronized with ~ transport clock
havlng a nominal period of time sufficlently long to allow the
meter to settle to an average voltage indication. During the
opposing one second alternate time in~ervals, a second signal
or reference envelope is generated by the microprocessor
through programmed delays at the speed envelope test point of
a determined time duration in width and is also synchr~nized
with the transport clock at the rate of twenty times ln
approximately one second. These alternate time interval
happenin~s are continued as long AS necessary for
adJusting ehe speed one-shot and observing a steady position of
the meter -- which steady position indlcates that the width of
the speed enyelope is equal to the width of the reference ~:
:: en~elope as any percentage difference in the width of the two
~velopes is directly proportional to the difference ln voltage
readings.
In view of the above d1scussion, the princ~pal ob~ect
;~ of the present invention is to provide a slmplifled method ~or
ad~usting the speed of a prime mover.
Another ob~ect of the present invention i~ to provide
a method utilizing present circuitry in apparatus whlch requires
-- 6 --
: ~ -
~ Q~346
speed ad~ustment of a prime mover .
An additional object of the present ~nvention is to
provide means for indicating the relative speed of a prime
mover.
A further ob~ect of the present i~ventlon is to
provide reference and speed envelopes at a test point for
observing indication of need for adjustment in speed of a prime
mover.
Additional advantages and features of the presant
lnvention will become apparent and fully understood from a !~
reading of the following description taken together wlth the
annexed drawlng, ln whlch:
Flg. 1 is a side elevational view of encoding mechan-
ism employing a stepping motor and with which the presen~
invention i~ assoeiated;
Fig. 2 is a diagrammatlc view of the ma~or components
of the stepping motor speed ad~usting system; .~:
Fig. 3 is a timing chart of the pulsing signals of
the system;
Fig. 4 ~s a dlagram showlng the sequence and time
dur~tion of speed and reference signals of the control system;
Flg. 5 is a flow diagram of the implementation of the
speed ad~ustment of the steppin~ motor;
Fig. 6 is a block diagram of the speed ~d~ustment
syRtem for a modlfied form of the invention~ -
Fig. 7 is a tim~ng chart of the pulsing signals o~
3~
the modification shown in Fig. 6;
Fig. 8 is a flow diagram of the implementation of the
speed ad~ustment of the lnvention modiflcation shGwn in Fig. 6;
Fig. 9, on the sheet with Figs. 6 and 7, ls a block
diagram of the speed ad~ustment system of a further modified
orm of the inventlon; and
Fig. 10, on the sheet with Fig. 8, is a timing chart
showing the relationship of th~ speed and ~he reference
envelopes to ~he clock pul~e.
The encGding mechanism of the preferred embodiment of
the instant invent~on basically includes a typewheel, a stepping
: motor for driving and controlling the! rotation and position of
the typewheel, and an electromagnetically operated h~mmer, the
impact of which can be controlled by potentiometers to regulate
hammer force to suit specific characters on the typewheel. Fig.
: 1 show3, in a side elevational viewt the important parts o~ such
~n encoding mechanism as supported from a m~unting plate 10 which
may be one side frame member of a business machine. A typewheel
12 with type characters 14 on the periphery thereof is driven
and controlled in incre~ental manner by a stepping motor 16~
and an aligner mechanism 18 is positioned adjacent the motor 1~.
The aligner mechanism 18 is provided with well-known al~gning
bar, etc. engageable with the typewheel 12 for holding the type-
wheel in precise position during the printing operation. A
ribbon 30 i5 caused to be driven in a path above the typewheel
and a check or like document 3~ may be placed or positloned above
-- 8 --
3~
the ribbon 30 to be contacted by the impact face 34 of a hamm~r
36 carried on a pivot 38 of a hæmmer frame 40. A hammer core
42 and a hammer coil 44 are carried on the frame 40 to operate
the hammer 36 against the return force of a spring 46. A timing
disc 48 having a plurality of slots or aper~ures 50 along the
circumference thereof is rotatably supported ad~acent the hammer
36 and the ~ypewheel 12, and is operably connected with the
motor 16. While the showing and the description of the encoding
mechanism are limited in scope, the various parts and the opera~
tion of these parts are generally well-kn~n in the encodlng of
documents.
~ In F~g. 2 is shown a block diagram of the ma~or
camponents of the speed ad~usting system for the stepplng motor
16, wherein a controller board 60 includes a microprocessor 62,
one type o which may be the MCS-4" as manufactured by Intel
Corporation~ associated with a memory 64 having instructions ~.
stored ~herein in any well-known manner for implementing the
invention, a clock 66 for providing pulses of a predetermined
rate to the microprocessor 62, and an input/output device 68
; 20 associated with the microprocessor 62 and the control circults
distal ~rom the board ~0. The memory 64 includes read only and ~;
random access (ROM and R~M) capability, and the microprocessor
has a counter for tracking the number of envelopes or repeats o
namlnal one second t~me periods. A delay one shot 69, of thP
monostable multivibrator type, ls triggered by the microprocessor
at programmed intervals and the microprocessor also receiveæ
- 9 -
3~L6
return signalx from the one-shot when the delay is completed.
The dri~er hardware 70 for the motor 16 is connected to the I/0
device 68 for recelving pulses therefrom for driving the motor
16. A speed one-shot 72y of the monostable multivibrator type,
receives trigger pulsing signals from the motor 16 via timing
d~sc 48 operated thereby and sends signals to the I/0 device 68,
the one-shot 72 having an ad~ustable device 74, in the form of
a potentiometer, for adjusting the width of the pulse or signal ~:
t~ the I/O device 6~. The motor driver hardware 70 ~nd the
10 speed one-shot 72 comprise a portion of driver board adjacent
the controller board. An exterlor connection from the I/O
module 68 also lncludes a signal path to a test point 76 to whlch
is connected a moving needle voltmeter 78, such voltmeter being
connected to a point 80 at ground potential.
A timing'ohart is shawn in Fig. 3 wherein the timing
relationship or "n" number of char~cter steps o the stepping
motor 16 i9 indicated only for a number of phase switching
t~mes. The fir~t phase switching shown as 90 causes the motor
16 to begin rotating frum a rest condition with speed one-shot
20 72 pulses 92 (two for each character step) being triggered by
the rotation of the motor and sensed by the microprocessor 62.
For a seven character step of the motor 16, a total of fourteen
such pulses 92 are triggered and are read by the microprocessor
62. Subsequent phase switchings (except for the final switch-
ing) occur on the falling edge of the speed one-shot pulses. It
is thus seen that the width of the speed one-shot pulses affect
- 10 -
.. ..
the times of phase switching and the speed of rot~tion of the
motor 16. As the pulsewldth 92 of the one-s~ots decreases, the
phase switchings 90 are compressed in time and the motor stepping
speed is increased~ whereas an increase in the width of the one-
shot pulses extends the time of phase switchings and the motor
stepping speed i8 decreased. In accordanee with derived para-
meters, there are 2 n phase switchings and 2 n speed one-sho~
pulses for n character steps. As illustrated in Fig. 3 9 the
leading edge of the 2 n-l speed one shot pulse 94 triggers a :~
delay one-sho~: pulse 96, and the final phase switching occurs
on the falling edge of this pulse.
: A speed signal or speed e~velope 98 of certain dura-
tion ls produced at the test point 76, such signal beglnning at
the time of first phase switching and ending at the triggering
of the delay one-shot pulse 96 (Fig. 3). The triggering of the
delay one-shot pulse 96 determines the time period or width of
the speed envelope 98. For a given .qequence covering seven
character~9 the wldth of the speed envelope pulse 98 is 23.5
~` milliseconds, such pulse width being achieved and maintained by
ad~usting ~he potentiometer 74 o the speed one-shot 72. If
this pulse width or speed enve~ope g8 is repeated at regular
intervals, the meter 78 (with a sufficiently long time constant),
connected between the test point 76 and ground 80; will indicate
a voltage whlch is proportional to the width of the speed
envelope 98. The voltage pulses of 0-5 volts produced at the
. test point 76 are read by the meter 78 as an average of the
- 11 -
~ 6
amplltudes of such voltages.
Durlng alternate time interv~ls of approximately one
~econd, i.e., period equal to 20 times nominal 50 milliseconds
clock pulse, the stepping motor 16 is caused to be moved 20
times through the seven character s~eps (speed envelope), with
the start of each seven character stepping sequence being
synchronized wi~h the transport clock 66 whlch has, as des~gnat-
ed above~ the nominal pulse period of 50 milliseconds and which
pulse period is of suffieient length to allow the meter 78 to
settle to an average voltage indication. Durlng the opposing
one second alternate timP intervals, the microprocessor 62 ~:~
generates, through programmed delay~ i.e., those delays which
are inherent within the instruction cycle times, a fixed
reference signal or envelope of 23.5 mllliseconds in width at
the speed envelope test point 7Sy such reference envelope being
also synchronized with the transport clock 66.and generated 20
~imes during such one second period. The test point 76 ser~es
as a common access port for both the sp2ed and reference signal~,
AS seen in Fig. 4, whlch shows the sequence of speed
and reference signals or envelopes appeArlng at the test point
76, the sequence is continued as long as required for completing
speed ad~ustment in accordance with the instant invention. The
sequence in Fig. 4 shows a series o such one second time
per~ods of alternate speed and reference en~elopes in relation
to the 20 time cy~les of the transport clock 66. With the
generation of such speed and reference signals at point 76, tha
- 12 -
39L~
speed one-sho~ 72 may~ if required~ be then adjusted through
the pulse width adjusting device 74 until the meter 78 needle
remains steady which indicates that the wid~h of thP speed
envelope ls equal to the wld~h of the reference envelope.
In analy~ing the relationship of the length of pulse
widths of ~he speed envelope and the reference envelope 9 it iq
seen that as the motor 16 is ro~ated the average voltage of the
- speed envelope 98 at the test point 76 i8 given by
VS ~ T~ X Vref
: 10 where Ts ~ width of speed envelope
Tx ~ period of transport clock
Vref - "ON" voltage! of speed envelope
Similarly, the average voltage of the reference
envelope at test po~nt 76 is given t)y
Vr ~ T x Vref
wher~
Tr ~ w~dth of reference envelope
The ratio of thes~ two voltage~ is glven by
ratio Vr Tr
wherein it iS seen that the voltage ratio is independent of
both Vref (the "ON" vol~age of the speed envelope) and the speed
of the transport clock assuming that any perturbations in the
period of the transport clock average out to zero.
The swlng of the needle on the meter 78 can ~180 be
used to indicate the relative width of the ~peed and reference
envelopes and whether the motor is running fast or slow. In ~-
this regard
Let T~ ~ Tr + ~ x Tr
where ~ ~ Ts - T~
~ that is, percent error ~ ~ x 100%
; the voltage ratio is given by
, ~rratio ~ TS ~ lr ~ ~ X Tr
It is thus seen that the percPntage difference in the
respective widths of the speed and reference envelopes is
directly proportional to the difference in the voltage readings~
Stepp~ng motor flnd speed ad~ustments in an encoding
mechanism generally have required in the past that a precise
time base generator be used to initla~e the seven character
steps repetitively at fixed intervals. The output of the speed
envelope is applied to a test point, however this voltage is
referenced to another test point having a voltage equal ~o the
average voltage ofithe sp ed envelope. A meter connected be-
tween these test points will then indicate zero volts at the
correct speed a~ustment.
~` Contrariwlse, the apparatus and method of the pres~nt
invention has eliminated the heretofore known drawbacks~ viz.
the meter must be ~ccurately calibrated to indicate zero volts
correctly, that the voltage at the reference test point must be
precise, and that a precise time base was needed. Additionally~
procedures have been simplified in that the test probe need not
be moved from one test point to another since the reference and
speed envelopes of the present invention are applied at the same
.,
. ~
- 14 -
3~ !
test point as used in the symmetry test for the motor, which
symme~ry test requires adjustment only for a steady needle on
the indicatlng device or meter.
In Fig. 5 is shown a fl~w diagram of the implementa^
tion of the speed ad~ustment on the encoding mechanism applica-
tion of the present invention wherein the program sets forth
and completes a series of steps by the microprocessor 62 for
controlling the speed of the stepping motor 16 in positioning
the typewheel 12. The first steps cover the ~etting of or
initiating the control count for twenty repeats of the seven
character sequence along with setting of a mode index of the
microprocessor to 7ero and synchronizing of negative and posi-
tive voltages of the transport clock 66. The mode index is used
to ascertain whether to output the speed envelope or reference
envelope to the test point 76. A twelve millisecond delay is
genera~ed to reflect the timing of motor positioning in nonmal
operation after whlch it is determined whether or not the
twenty repeats have been completed. If such twenty repeats are
completed and the mode of the motor output is zero9 the mode ~-
index is complemented to change the mode from the motor output
to the reference output. The counter or regis~er associated
with the microprocessor 62 counts up by one on generation of the
speed envelope 98, and likewise counts up by one on generation
of the reference envelope, the generation of such speed and
reference envelopes being under control of the micropxocessor.
If the speed test mode index equals zero, the test output is ;~
- 15 -
. -
.. .
)3~6
turned on ~ust ~efore the first phase switching of the motor
; 16, the motor is moved clockwise ~hrough the seven character
steps, and then the test output is turned off just prior to
~; the "next-to-last" phase swltching. If the mode index does not
equal zero after complementing from motor to reference output,
the test output signal is turned on and a 24 millisecond delay
is generated to the reference output. In elther case~ a repeat
operation counter (Fig. 5) is incremented and another cycle is
then begun. Implementation of the speed ad~us~ment of the
motor 16 may include an alternate step to that of incrementing
the counter near the end of the program~ such alternate s~ep
giving an indication whether the diagnostics switch is on or
off. If this switch is still on, another cycle is set and com-
pleted. If this switch is off, the test is completed.
A modified form of the present inventive concept is
shown in Figs. 63 7, and 8 for ad~ustment of the idllng speed
of an automobile engine 120 (Fig, 6~ wherein a voltmeter 122
s connected between the test point P of a test set 124, which
test set is connected by a spark plug lead 130 to the engine
120. The voltmeter 122 is connected to ground 126 and an idle
ad~usting device 128 (spark control~ fuel-air mixture control,
etc.) is used to set the idle engine speed. Fig. 7 shows a
timing diagram of slgnals or pulses ln the idle ad~u~tment of
:
the engine 120, with the engine being exemplified as running
fast or above the correct idle speed Basically, the speed of
the engine 120 ls a function of the rate of firing of the spark
- 16 -
. " ~ :
plugs employed, the ~iming diagram of Fig. 7 showing only the
successive firings of one plug. For each pulse 132 of a flxed
number of firings N of the spark plug, a microprocessor in the
test set 124 detects the firing and outputs a pulse 134 of
known width Tl, which pulse is output to test point P. The
time between the ccmpletion of one pulse and the start of the
next pulse (shown as T2V) is variable and is a funol~n of the
engine speed. After completion of the above N firings, the
microprocessor for N repeat cycles outputs to ~est point P a
~ 10 pulse 136 of width T~ followed by no pulse for a fixed time
T2r which time T2r is chosen to be equal to the width T2V when
the engine is adjusted to the desired idle speed. At the com- -~
pletion of N cycles of generated reference pulses 136 at the
test point P, the firing cycle is repeated until the engine
speed ad~ustment is completed. The moving needle voltmeter 122
connected between test point P and ground 126 will indicate a
-~ steady needle position when the engine idle speed is correctly
:: .
ad~usted to the desired value. The number of cycles N of gen-
erated reference pulses at test point P must be suff~len~ to ~'~
allow the meter 122 to reach a steady state condition.
In F~g. 8 is shown a f low chart of the implementation
of the engine speed ad~ustment. Starting at I ~counter set)
- equal to zero, the output pulse 134 of width Tl is caused to
appear at test point P when the spark plug fires. This indica-
tion results in 1 3 I ~ l. The next step detenmines whether or
not I ~ N. If not, the above sequence is repeated until I - N.
- 17 -
: .......... , . ~
~ 3~ 6
When I - N, I is then set to zero. An output pulse 136 of
wldth Tl is caused to be output to test point P, followed by a
delay of tlme T2r durlng which no signal i8 output to test
point P. This results in I = I ~ 1. The next step determines
whether or no~ I a N. If not, the sequence is repeated until
I - N~ When I = N, the sequence associated with the spark plug
firing is repeated. The above cycle continues until the meter
122 connected to test point P indicates a steady reading,
thereby indicating correct ad~ustment of the engine idling speed.
A further form of the inventive concept is shown in
Fig. 9 wherein an inductlon motor lS0 drives a turn~able 152.
A sensor 154 senses the speed of rotation of the turntable and
is connected to a test set 156, A speed ad~usting de~ice 158
is connected to the motor 150, which device may, for example,
be in the form of a potentiometer to effect speed ad~ustment
to the motor, as determined by the needle of a voltmeter 160
connected between a te~t point P of the test set 156 and a
ground 162. Again the test set includes a microproce~ssor with
associated apparatus and circuitry to program the various steps
of implementing the adjustment procedure. It is to be noted
that while a microprocessor is well-adapted to provide the
processing logic of such various steps, hardwired logic could
also be used in the invention~
To further aid in understanding the timing of the
respective pulses or signals, Fig. 10 shGws a timing chart of
the relationship between the continuous cycle of clock pulses
- 18 -
~ 3
and the speed and reference envelopes, which chart relates one
test condition of times of pr~determined and actual operational
signals. As mentioned earller, the clock pulse has a nominal
period of 50 milliseconds, designated as pulse 170, such pulse
period being constant during the entire time of operation of
the adjusting procedure. Likewise, the reference envelope has
a predetermined time of 23.5 milliseconds for the first portion
172 of its cycle~ such time periods also being constant during
the entire time of operation. Regarding the speed envelope
(i.e. the moving of the stepping motor 16 through the seven
character steps), it is assumed that the speed of such motor
requires an ad~ustment thereof to properly posltion the type
characters 14 for printing. While an initial time period or
pulse may be of shorter or longer duration, for purposes of the
present description, a first portion 176 o the speed envelope
is shcwn in Fig. 10 as being lS.5 milliseconds with the latter
portion then being 34.5 milliseconds. It is of course readily
noted that the first portion of the speed envelope may have an
initial time per~od longer than 23.5 milliseconds and that the `;~
20 ad3ustment would be needed to correct back to the 23.5 milli- ;
second period Also9 while a plurality of like speed envelopes
:~will foll~w initially until the required ad~ustment operation
is commenced, for purposes of illustration a first portion 180
of a second speed envelope is shown in Fig. 10 as 16.5 milli-
seconds with the second portion 182 of such envelope being 33.5
milliseconds. Further, the first portion 184 of a third speed
-- 19 --
.. , ~ . . ... . .
391t~
envelope ls 17,5 milliseconds with the latter portion of such
envelope being 32,5 milliseconds, After the number of like
speed envelopes have been lnitially seen at the test point 76,
through ad~ustment of the potentiometer 74 the above representa-
tive speed envelope changes occur until the first portion 186 of
a succeeding speed envelope has a time of 23.5 milliseconds
which is the desired time for the speed envelope as compared to
the reference envelope. The above pul~e width adjustment of the
speed envelope ls performed during a period of time by observing
the position of the needle of the voltmeter 78 while ad~usting
the potentiometer 74 to produce a speed envelope of 23.5
milliseconds comparable to the 23.5 millisecond period of the
reference envelope.
It is thus se~n that herein shown and described ls
apparatus and method for adjustlng thle speed of a prime mover
wherein logic is provided by a microprocessor in a manner which
utilizes alternate signals in clrcuitry along with means for
indicating when the prime mover is or is not running at the
desired speed. The desired speed of such prime mover is attained
when the width of the speed envelope equals the width of the
reierence envelope. The apparatus and method compri6es a con-
~rol system whlch enables the accomplishments of the o~jects
and advantages mentioned above, and while several embodiments ~ -
have been disclosed herein9 variations thereof may occur to
those skilled in the art. It is contemplated that all such var-
iations not departing from the spirit and scope of the invention
hereof are to be construed in accordance with the followingclaims.
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