US3793509A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for counting work cycles of electrically driven devices
Assignee: Caterpillar Inc
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Filing: 1971-12-23
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Granted: 1974-02-19
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Expires: 1991-12-23
Abstract
Abstract An accurate count of the number of workpieces processed on an electrically driven machine tool is maintained by a counter controlled by a circuit which responds to the changes of drive motor current in the course of each work cycle. As the counting system is not dependent upon detection of any mechanical movement, critical elements of the system may be inaccessibly 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 workpiece and is insensitive to supply current fluctuations arising from other causes such as motor starting surges and the like.
Inventors
- 👤 T Isnard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:18
CPC Classifications
G; G07; G07C; G07C3/00; G07C3/02; G07C3/04; G06; G06M; G06M1/00; G06M1/08; G06M1/10
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
172 words
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, current sensing means coupled to said conductor means to sense current changes therein and having means for producing a first continuous voltage which changes in response to said changes of said current, 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, means for comparing said first and second voltages for producing an output signal as said first voltage reaches a predetermined relationship to said second voltage, and 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.
Claim 2
Independent Claim
172 words
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, current sensing means coupled to said conductor means to sense current changes therein and having means for producing a first continuous voltage which changes in response to said changes of said current, 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, means for comparing said first and second voltages for producing an output signal as said first voltage reaches a predetermined relationship to said second voltage, and 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.
Claim 3
Dependent Claim
117 words
A device as defined in claim 1 wherein 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, and wherein said voltage sensing means for producing said second voltage comprises 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 said source of electrical power, a second full wave rectifier connected across the secondary winding of said transformer, and an adjustable potentiometer connected across said rectifier.
Claim 4
Dependent Claim
69 words
A device as defined in claim 1 wherein said circuit means comprises a Schmitt trigger circuit having an output which changes between a first and a second predetermined fixed electrical states in 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.
Claim 5
Dependent Claim
79 words
A device as defined in claim 1 wherein 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.
Claim 6
Dependent Claim
41 words
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.
Claim 7
Independent Claim
331 words
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 of alternating electrical current and wherein at least one increase of current in said conductors occurs in the course of each work cycle due to increased loading of said motor, comprising: current sensing transformer means inductively coupled to at least one of said conductors for sensing said current increase therein, 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 signals and having means for recording an accumulated total of said count signals, relay means connected between said input terminals of said counter and said source of electrical current for transmitting said count signals to said counter in response to actuation of said relay means, and circuit means for actuating said relay means in response to said output signals from said detector means.
Claim 8
Independent Claim
331 words
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 of alternating electrical current and wherein at least one increase of current in said conductors occurs in the course of each work cycle due to increased loading of said motor, comprising: current sensing transformer means inductively coupled to at least one of said conductors for sensing said current increase therein, 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 signals and having means for recording an accumulated total of said count signals, relay means connected between said input terminals of said counter and said source of electrical current for transmitting said count signals to said counter in response to actuation of said relay means, and circuit means for actuating said relay means in response to said output signals from said detector means.
Claim 9
Dependent Claim
30 words
The combination defined in claim 6 whereiN said circuit means has time delay means for blocking reactuation of said relay means for a predetermined interval after a prior actuation thereof.
Claim 10
Dependent Claim
35 words
The combination defined in claim 6 further comprising a breakdown device connected between said other terminals of said variable voltage means and said comparison means for limiting said third voltage to a predetermined maximum value.
Claim 11
Dependent Claim
21 words
The combination defined in claim 6 further comprising a differentiator circuit coupling said other terminals and said voltage change detector means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-18 | 1977-08-20 | 1978-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-18 | 1981-08-20 | 1982-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-18 | 1985-08-20 | 1986-02-19 | $7700.00 | Window Closed / Lapsed |