US3793509A - Method and apparatus for counting work cycles of electrically driven devices - Google Patents

Method and apparatus for counting work cycles of electrically driven devices Download PDF

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Publication number
US3793509A
US3793509A US00211247A US3793509DA US3793509A US 3793509 A US3793509 A US 3793509A US 00211247 A US00211247 A US 00211247A US 3793509D A US3793509D A US 3793509DA US 3793509 A US3793509 A US 3793509A
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United States
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voltage
current
output
circuit
counter
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Expired - Lifetime
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US00211247A
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English (en)
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T Isnard
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Caterpillar Inc
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Caterpillar Tractor Co
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Assigned to CATERPILLAR INC., A CORP. OF DE. reassignment CATERPILLAR INC., A CORP. OF DE. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: CATERPILLAR TRACTOR CO., A CORP. OF CALIF.
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    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C3/00—Registering or indicating the condition or the working of machines or other apparatus, other than vehicles
    • G07C3/02—Registering or indicating working or idle time only
    • G07C3/04—Registering or indicating working or idle time only using counting means or digital clocks
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06M—COUNTING MECHANISMS; COUNTING OF OBJECTS NOT OTHERWISE PROVIDED FOR
    • G06M1/00—Design features of general application
    • G06M1/08—Design features of general application for actuating the drive
    • G06M1/10—Design features of general application for actuating the drive by electric or magnetic means

Definitions

  • the counting system is not dependent upon detection of any mechanical t.mq stnsnsgfi salslsm nis cithwz x be accessibly located to avoid possible tampering with the count.
  • the system can be adapted to counting work operations which involve more than one motor current peak in connection with processing of a single.
  • Counting devices heretofore employed for this purpose have involved various means for sensing some mechanical movement at the tool or the like which occurs in the course of each work cycle. Such devices are inherently susceptible to tampering or manipulation whereby false counts may be recorded. Moreover, such devices may be complex and bulky, prone to wear and difficult to install on certain machines.
  • This invention is a method and apparatus for counting work cycles in an electrically driven system which is less susceptible to tamperingand which may utilize compact economical elements. These results are accumplished by sensing and counting changes of electrical current to the drive motor or the like which occur in the course of each work cycle.
  • An electrical motor for example, typically draws an increased current each time it is loaded to perform a work operation.
  • means are provided for discriminating against current fluctuations which arise from other causes, such as the current surges associated with initial starting of a motor, and the system is adaptable to work cycles which may involve a series of current variations in the course of a single cycle.
  • FIG. 1 is an elevation view of an inertia welding machine showing elements of a work cycle counting system associated therewith,
  • FIG. 2 is a circuit diagram showing electrical elements of the work cycle counting system of FIG. 1, and
  • FIG. 3 is a circuit diagram showing a modified circuit for use where multiple current peaks may occur in the course of a single work cycle.
  • Welder 11 may have a base 12 supporting a rotatable spindle 13 which carries a flywheel l4 and a rotary chuck 16, the spindle, flywheel and rotary chuck being driven by an electrical motor 17 which is of the threephase alternating current form in this example.
  • an electrical motor 17 which is of the threephase alternating current form in this example.
  • Slidably positioned on base 12 opposite the rotary chuck 16 is a tailstock 15 carrying a non-rotating chuck 18.
  • Tailstock 15 and chuck 18 may bemoved towards the rotary chuck 16 and away therefrom by suitable means such as a hydraulic cylinder 21 within base 12.
  • the drive motor 17 is coupled to a suitable three-phase alternating current power supply 22 through three conductors 23, 24 and 26 and a switch 27 for selectively energizing the motor.
  • the current drawn by motor 17 from power supply 22 is a function of the load on the motor and thus rises during the period that the spindle l3, flywheel l4, and other rotating elements are in the process of being accelerated.
  • the current drawn by motor 17 from power supply 22 is a function of the load on the motor and thus rises during the period that the spindle l3, flywheel l4, and other rotating elements are in the process of being accelerated.
  • the counter 29 is a visually readable type mounted on the cabinet 32 of the welder 11 which contains other electrical control elements of the welder.
  • the circuit 31 which drives the counter is within the closed cabinet 32 where it is relatively inaccessible to the operator. In some instances the circuit 31 may be situated remote from the welder 11 as it operates wholly through electrical connections to the conductors 23, 24 and 26 which supply electrical current to the motor and these conductors'may extend a considerable distance away from the welder.
  • Operating power for the counter circuit 31 is obtained through conductors 33 and 34 which connect to two of the motor supply current conductors 26 and 24 respectively. In order that the circuit 31 remainenergized when the motor control switch 27 is open, this connection is preferably made between that portion of the conductors 26 and 24 which extendbetween switch 27 and power supply 22.
  • a pair of conductors 36 extend from the circuit 31 and are connected to the secondary of a current sensing trans former 35 having the third motor power supply lead 23 as a primary.
  • the two conductors 36 connect to opposite ends of the primary coil of an adjustable transformer 37.
  • the secondary winding of transformer 37 is in turn connected across the input terminals of a full wave diode bridge rectifier 38.
  • One output terminal of rectifier 38 connects to a terminal 39 through a resistor 41 while the other output terminal of the rectifier connects directly with a terminal 42.
  • a DC voltage E-1 appears between terminals 39 and 42 and has a magnitude proportional to the current in motor power supply conductor 23.
  • a capacitor 43 and resistor 44 are connected across the output terminals of the rectifier.
  • a zener diode 46 is also connected across the output of the rectifier.
  • voltage E4 is continually compared with a second voltage E-2 derived from the motor power supply conductors and' a work cycle count is initiated only when a rise of voltage E-l is unaccompanied by a corresponding rise of voltage E 2.
  • the primary winding of asecond adjuatable transformer 48 is connected between the previously described power conductors.
  • 33 and 34 former 48 is connected across the input terminals of a second full wave diode bridge rectifier 49.
  • a potentiometer 51 and resistor '52 are connected in series the capacitor 63 and resistor 64 differentiate the de across the output terminals of rectifier 49 and a ripple V smoothing capacitor 53 is also connected across the output terminals in parallel relationship with the potentiometer and resistor.
  • difference voltageE3- When motor 17 is not loaded, difference voltageE3- remains essentially constant at the value determined by zener diode 56.
  • voltage E-1 rises due to motor loading voltage E-3 decreases and this decrease is caused to initiate a work cycle count.
  • input conductors 58 and 59 of an amplifier 61 are connected to ground conductor 54 and terminal 39 respectively through a differentator circuit 62.
  • amplifier input 59 connects to terminal 39 through a capacitor 63 while amplifier input 58 connects directly with ground conductor 54 and a resistor 64 is connected across the amplifier input conductors whereby crease of voltage E.3 accompanying a work cycle and apply the differentiated signal to the amplifier input.
  • Amplifier 61 in turn, applies an amplified signal tothe input 66 of aSchmitt trigger circuit 67.
  • DC operating voltage for both the amplifier 61 and Scmitt triger 67 is obtained through a third transformer 68 having a primary winding connecting to the previously described conductors 33 and 34 respectively and having a secondary winding connected across the input terminals of a third full wave diode bridge rectifier 69.
  • the negative output terminal of rectifier 69 is grounded while the positive output terminal connects with a power terminal 71 for the Schmitt trigger circuit 67 and amplifier 61.
  • a capacitor 70 is connected between the positive output terminal and ground.
  • the collector of transistor 72 of the amplifier 61 connects with power terminal 71 through a resistor 73 and an additional resistor 74 of the Schmitt trigger.
  • amplifier 61 may consist of a resistor 77 connecting the base of the transistor with amplifier input 59 and a resistor 78 connecting the transistor emitter with grounded input 58.
  • a protective diode 79 is connected between the transistor emitter and input 59 and a capacitor 81 is connected between the collector and ground to suppress transient voltage spikes.
  • differentiator 62 applies a momentary voltage to the base of transistor 72 through base resistor 77 causing the transistor to conduct.
  • the input 66 of Schmitt trigger 67 is connected to the collector of transistor 72 and thus the momentary conduction of the transistor causes a momentary voltage decrease at input 66.
  • Schmitt trigger 67 may consist of a transistor 82 having a base connected to input 66 through a resistor 83 and having a collector connected to the power supply terminal 71 through a resistor 85 and resistor 74.
  • a zener diode 84 is connected between the emitter of transistor 82 and ground and diode 86 is connected between the emitter and-base of the transistor. Accordingly transistor 82 is normally conductive and becomes non-conductive when the previously described momentary voltage drop is applied to the base through input 66.
  • another zener diode 87 is connected between power supply terminal 71 and ground through resistor 74. Zener diode 87 also has the effect of providing a constant operating voltage to amplifier 61.
  • a capacitor 88 connected between the base of transistor 82 and ground avoids stopping of conduction through the transistor in response to brief spurious voltage transients.
  • Schmitt trigger 67 further includes a second transistor 89 having a base connected to the collector of transistor 82 and having an emitter connected to the emitter of transistor 82 and thus to ground through zener diode 84.
  • the collector of transistor 89 connects to power supply terminal 71 through a relay driver coil 91 and also through a diode 92 which protects the transis tor against transient voltages arising from the collapse of the magnetic field of coil 91.
  • transistor 89 is nonconductive as long as transistor 82 is in conduction. While transistor 82 ceases to conduct in response to a signal at input 66 a positive voltage rise occurs at the base of transistor 89 which then conducts to energize coil 91.
  • Relay contacts 93 are connected between one input of counter 29 and power conductor 34 in se- 6 ries with a load resistor 94, the other input of the counter being connected directly to power conductor 33. Accordingly each momentary closing of contacts 93 initiated by the current increase at motor 17 applies one pulse count to counter 29 which displays the total of pulse counts received and thus visually indicates the number of work cycles which have been performed by motor 17.
  • FIG. 3 illustrates a modified form of the circuit in which the counter 29 will record a single additional count for each work cycle of a machine of this kind wherein several current increases may occur during the work cycle.
  • the circuit 31' of FIG. 3 includes power supply conductors 33 and 34 which connect to two of the three conductors 26 and 24 respectively between motor power supply 22 and the three-phase motor 17 and further includes a current sensing transformer 35' having the third motor current conductor 23 as a primary, no other connections to the motor and power supply being necessarily required.
  • Certain portions of the modified circuit 31' of FIG. 3 are essentialy similar to corresponding portions of the previously described circuit and accordingly will not be redescribed in detail, the elements of these unmodified portions of the circuit being identified in FIG. 3 by primed reference numerals corresponding to the reference numerals used in FIG. 2 for similar elements. These essentially unmodified portions of the circuit of FIG.
  • a transformer 68 and rectifier 69' coupled to conductors 33 and 34 to provide DC operating power at a terminal 71 and an additional transformer 48' and rectifier 49 for providing a reference voltage E-2' between a terminal 42 and grounded conductor 54'.
  • Another transformer 37' and rectifier 38' provide a voltage E-l' between terminal 42 and a terminal 39 that is a function of the magnitude of current in the motor power conductor 23 as previously described.
  • a zener diode 56 is connected between terminals 39' and 54' to limit the difference between voltages E-2' and E-l' to a predetermined maximum.
  • a differential voltage 1-3-3 is present across the zener diode 56' and when voltage E-l increases responding portions of the previously described circuit the FIG. 3 circuit is somewhat more susceptible to false counts from brief voltage transients if appropriate corrective measuresare not taken.
  • anti-interference capacitors are'provided at various points in the circuit. This includes capacitors 101 and 102 each connected between'ground and a separate end of the primary'of transforrn'erx48' and a pair of capacitors l03 and '104 similarly connected between opposite ends of the primary of trans former'37' and ground. For similar purposes, still 811.7,.
  • Thie;base of, transistor '1 27 is connected toiground through a resistor tional count signals' to counter 29 that their flip-flop 118 is arranged to remain iin the set condition and therefore to be insensitive .to: additional input pulses for a predetermined'period corresponding to a time just a slightly less "than-the period required for'full work cycle of motor 17;
  • a transistor 127 has a collectoriconnected ,to power supply terminal 71 "through a voltagedropping resistor 132 and to the junction between resistor 129 and ca ⁇ set the flip-flop.
  • one base electrode of i unijunction transistor 116' is coupled to DC power'ter-,
  • unijunction transistor is coupled to differentiator terminal 109 through a resistor 121.
  • the emitter of unijunction transistor 116 is coupled to the terminal 111 of the differentiator whereby a decrease of voltage E-3 causes the unijunction transistor to become conductive for a brief period.
  • Input 117 of flip flop 118 is connected to the junction between resistor 119 and the unijunction transistor 116 and thus a positive voltage at input 1 17 is momentarily decreased each time transistor 116 conducts.
  • the ernitterof transistor 134 is connected tog'g r ound'throughresistor 132 and to "the emitter of transistor 127J1 ejcollector'ofitransistor f r I 134 isac'oupled topfiwrsupply tenninalfll'ilthrough a "resistor 141'.
  • the above described cross couplings of the transistors 1'271land 134 result. in. a' bistable action, Y wherein conduction oforie transistor l27f or l3 f4'pre eludes conductionof the other, With transistor 127; initially in a conducting condition, transistor 1534 is biased.
  • transistor'l34 conduction through transistor'l34 is'stopped' and the circuit assumes the origi'nal'stable reset state.
  • the unijuhction' transistor 143 is trig I gered a predetermined interval' aft'er the flip-flop 118 is set thereby producing a reset pulse acrossresistor 14 9.
  • the reset pulse is transmitted to the base of tran- I sistor 134 by a capacitor 151 to turnofi transistor' l34fl and therebycause theflip-flop 118 to revert to the ini tial reset state.
  • one input to the counter is connected to AC power conductor 33 while the other counter input connects to AC power conductor 34 through relay contacts 124, a resistor 154 and a diode 156.
  • Resistor 154 and diode 156, together with a capacitor 157 act to rectify the count signal voltage transmitted to counter.
  • a capacitor 158 and resistor 159 are connected across relay contacts 124 to suppress arcing at the contacts.
  • a device for counting work cycles performed by an electrically operated apparatus having conductor means for connection to -a source of electrical power comprising:
  • a counter having input means for receiving count signals and having means for recording the number of said count signals received at said input,
  • said circuit means comprises a Schmitt trigger circuit having an output which changes between a first and a second predetermined fixed electrical states response to said output signals from said comparing means, and means controlled by said output of said Schmitt trigger for transmitting a count signal to said counter upon each change of state of said Schmitt trigger output.
  • said circuit means comprises a bistable multivibrator flip-flop circuit having an output which changes state in response to said output signals from said comparing means to assume a set condition, means coupled to said output of said flip-flop for transmitting a count signal to said counter each time said flip-flop assumes said set condition, and means for resetting said flip-flop circuit a predetermined time interval after said flip-flop circuit is set.
  • A'device as defined in claim 1 wherein said means for producing said first voltage has filter means for supressing any significant change of said first voltage when said change of said current is of less duration than a predetermined interval.
  • a device for counting work cycles performed at a machine tool or the like which is driven by an electrical motor having conductors which connect with a source 1 of alternating electrical current and wherein at least voltage sensing means coupled to said conductor means independently of said current sensing means for producing a second continuous voltage which is proportional to the voltage being applied to said apparatus by said source,
  • v circuit means coupled to said comparing means and to said counter input and having means for transmitting count signals to said counter input in response to output signals from said comparing means.
  • said current sensing means comprises a first transformer inductively coupled to said conductor means which connects said electrically operated apparatus with said source of electrical power and a first full wave rectifier connected to said transformer to produce said first voltage
  • said voltage sensing means for producing said second voltage comprises 7 a second transformer having primary and secondary windings and having said primary windings connected between a pair of conductors of said conductor means which connects said electrically operated apparatus with one increase of current in said conductors occurs in the course of each work cycle due to increased loading of said motor, comprising:
  • variable voltage means including a first rectifier coupled to said transformer means and having a pair of output terminals across which a first continuous voltage is generated which varies in response to said current changes, comparison means connected between a pair of said electrical conductors independently of said transformer means and having a second rectifier and output terminals across which a second continuous voltage is produced which is proportional to the voltage supplied to said motor through said conductors, conductive means interconnecting one output terminal of said variable voltage means with one output terminal of like polarity of said comparison means whereby a third voltage is present between the other terminals of said variable voltage means and said comparison means which third voltage varies in response to said changes of current in said conductors, voltage change detector means coupled between said other terminals of said variable voltage means and said comparison means and having an output for transmitting a signal when said third voltage is reduced to a predetermined value by an increase of said first voltage relative to said second voltage, a counter having input terminals for receiving count
  • relay means connected betvveensaid input terminals of said counter and said source of electrical current

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Ac Motors In General (AREA)
US00211247A 1971-02-17 1971-12-23 Method and apparatus for counting work cycles of electrically driven devices Expired - Lifetime US3793509A (en)

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FR7105427A FR2125708A5 (enrdf_load_stackoverflow) 1971-02-17 1971-02-17

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BE (1) BE779262A (enrdf_load_stackoverflow)
FR (1) FR2125708A5 (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4038617A (en) * 1974-09-27 1977-07-26 Joseph Milom Apparatus for indicating the output of a machine
US4965513A (en) * 1986-09-30 1990-10-23 Martin Marietta Energy Systems, Inc. Motor current signature analysis method for diagnosing motor operated devices
US5029188A (en) * 1989-11-03 1991-07-02 Joyner Engineers And Trainers Apparatus for monitoring operation cycles of an electrically actuated device
US6815650B1 (en) * 2004-01-02 2004-11-09 Kathleen M. Bartz Energization cycle counter for induction heating tool
WO2005069694A3 (en) * 2004-01-02 2005-09-09 Kathleen M Bartz Energization cycle counter for induction heating tool

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1744840A (en) * 1924-11-25 1930-01-28 American Telephone & Telegraph Voltage-indicating and translating device
US3329806A (en) * 1963-11-08 1967-07-04 Microdyne Inc Monitoring circuits
US3346725A (en) * 1964-07-10 1967-10-10 Gen Motors Corp Commutator pulse counting apparatus
US3604904A (en) * 1969-02-06 1971-09-14 Radex Corp Monitoring device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1744840A (en) * 1924-11-25 1930-01-28 American Telephone & Telegraph Voltage-indicating and translating device
US3329806A (en) * 1963-11-08 1967-07-04 Microdyne Inc Monitoring circuits
US3346725A (en) * 1964-07-10 1967-10-10 Gen Motors Corp Commutator pulse counting apparatus
US3604904A (en) * 1969-02-06 1971-09-14 Radex Corp Monitoring device

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4038617A (en) * 1974-09-27 1977-07-26 Joseph Milom Apparatus for indicating the output of a machine
US4965513A (en) * 1986-09-30 1990-10-23 Martin Marietta Energy Systems, Inc. Motor current signature analysis method for diagnosing motor operated devices
US5029188A (en) * 1989-11-03 1991-07-02 Joyner Engineers And Trainers Apparatus for monitoring operation cycles of an electrically actuated device
US6815650B1 (en) * 2004-01-02 2004-11-09 Kathleen M. Bartz Energization cycle counter for induction heating tool
US20050145621A1 (en) * 2004-01-02 2005-07-07 Bartz Kathleen M. Energization cycle counter for induction heating tool
US20050145620A1 (en) * 2004-01-02 2005-07-07 Bartz Kathleen M. Energization cycle counter for induction heating tool
WO2005069694A3 (en) * 2004-01-02 2005-09-09 Kathleen M Bartz Energization cycle counter for induction heating tool
US6965098B2 (en) * 2004-01-02 2005-11-15 Bartz Kathleen M Energization cycle counter for induction heating tool
US7041946B2 (en) 2004-01-02 2006-05-09 Bartz Kathleen M Energization cycle counter for induction heating tool

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FR2125708A5 (enrdf_load_stackoverflow) 1972-09-29
BE779262A (fr) 1972-08-11

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Owner name: CATERPILLAR INC., A CORP. OF DE.,ILLINOIS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905

Effective date: 19860515

Owner name: CATERPILLAR INC., 100 N.E. ADAMS STREET, PEORIA, I

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905

Effective date: 19860515