US3601773A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wireless r. f. radiation tachometer
Assignee: HARTMAN MARINE Inc
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Filing: 1969-06-16
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Granted: 1971-08-24
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Expires: 1989-06-16
Abstract
Abstract A tachometer which does not require any wired connections or inductive probes. It picks up radiation from ignition spark discharges and the like, and uses these to trigger a tunnel diode which activates a pulse-stretching monostable multivibrator. An ammeter is in series with the output current of the multivibrator, and is calibrated in r.p.m. The nonretriggerable period enhances the accuracy of the tachometer by providing noise blanking. A switching circuit adjusts the electrical value of a coupling network between stages of the multivibrator and adjusts the period thereof to accommodate two, three, four or six cylinder internal combustion engines without sacrificing any of the noise blanking capability. The coupling network incorporates a plurality of matched timing capacitors, enabling the tachometer to be calibrated for any number of engine cylinders by means of a single potentiometer.
Inventors
- 👤 Edward Frieling
- 👤 William G Konos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:09
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/4802; G01P3/4807
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
241 words
In a remotely responsive tachometer for measuring the angular speed of a motor having spark-generating means which radiates bursts of permanently escaping electromagnetic energy at radio frequencies over substantial distances in correspondence with its spark discharges, in addition to the magnetic induction field which surrounds the spark currents and which ultimately collapses and returns its energy to said spark-generating means when such currents terminate; said tachometer being of the type including a support having mounted thereon an indicator-driving circuit responsive to electrical pulses representative of spark discharges for generating an electrical indicator-driving signal having a magnitude substantially proportional to the repetition rate of said spark discharges, and visual indicating means responsive to said indicator-driving signal for providing an indication of the angular speed of the motor; the improvement comprising: an R.F. detection circuit including a threshold R.F. detector and means biasing said detector near enough to its threshold so that said detector exceeds said threshold at least primarily in response to said permanently escaping bursts of electromagnetic energy radiated by said spark discharges, independently of the magnetic induction field of the spark current; said detection circuit being mounted on said support and arranged so that the exceeding of said threshold by said detector causes said detection circuit to produce said sparkdischarge-representing electrical pulses in correspondence with said bursts of radiated electromagnetic energy detected thereby; and said indicator-driving circuit being connected to respond to said electrical pulses produced by said detection circuit.
Claim 2
Dependent Claim
241 words
In a remotely responsive tachometer for measuring the angular speed of a motor having spark-generating means which radiates bursts of permanently escaping electromagnetic energy at radio frequencies over substantial distances in correspondence with its spark discharges, in addition to the magnetic induction field which surrounds the spark currents and which ultimately collapses and returns its energy to said spark-generating means when such currents terminate; said tachometer being of the type including a support having mounted thereon an indicator-driving circuit responsive to electrical pulses representative of spark discharges for generating an electrical indicator-driving signal having a magnitude substantially proportional to the repetition rate of said spark discharges, and visual indicating means responsive to said indicator-driving signal for providing an indication of the angular speed of the motor; the improvement comprising: an R.F. detection circuit including a threshold R.F. detector and means biasing said detector near enough to its threshold so that said detector exceeds said threshold at least primarily in response to said permanently escaping bursts of electromagnetic energy radiated by said spark discharges, independently of the magnetic induction field of the spark current; said detection circuit being mounted on said support and arranged so that the exceeding of said threshold by said detector causes said detection circuit to produce said sparkdischarge-representing electrical pulses in correspondence with said bursts of radiated electromagnetic energy detected thereby; and said indicator-driving circuit being connected to respond to said electrical pulses produced by said detection circuit.
Claim 3
Dependent Claim
91 words
A tachometer as in claim 1 wherein said threshold detector includes a tunnel diode, and said biasing means biases said tunnel diode just below its switching threshold, and said detection circuit is connected for picking up said radiated energy and applying it to drive said tunnel diode beyond said switching threshold; and wherein said detection circuit is responsive to switching of said tunnel diode and arranged so that the output of said detection circuit has a magnitude which is substantially proportional to the repetition rate of said tunnel diode switching events.
Claim 4
Dependent Claim
100 words
A tachometer as in claim 1 wherein said indicator-driving circuit comprises: a monostable multivibrator having a predetermined period exceeding the duration of said spark-discharge-representing pulse; means causing said multivibrator to trigger in response to a spark-discharge-representing pulse whereby to generate a multivibrator pulse longer than said spark discharge representing pulse for Pulse-stretching purposes; said indicator-driving circuit being responsive to said multivibrator to produce output pulses, the duration and repetition rate of which are controlled respectively by the period and repetition rate of said multivibrator, whereby the output current of said indicator-driving circuit is substantially proportional to said multivibrator repetition rate.
Claim 5
Dependent Claim
86 words
A tachometer as in claim 3 wherein said multivibrator comprises: a first stage responsive to said spark-discharge-representing pulse; a second stage for latching said first stage during the period of said multivibrator; and impedance means connected between said multivibrator stages for causing said second stage to latch said first stage during said multivibrator period, and allowing said second stage to release said first stage at the conclusion of said multivibrator period, and arranged so that value of said impedance means determines the period of said multivibrator.
Claim 6
Dependent Claim
61 words
A tachometer as in claim 4 further comprising: means for adjusting the electrical value of said impedance means whereby to adjust the period of said multivibrator in order to adjust the duration of said indicator-driving circuit output pulses to compensate for a change in the repetition rate of said pulses due to a different number of spark discharges per motor revolution.
Claim 7
Dependent Claim
36 words
A tachometer as in claim 5 wherein: said adjusting means is arranged to adjust the electrical value of said impedance means in discrete steps corresponding to different, integrally related numbers of spark discharges per motor revolution.
Claim 8
Dependent Claim
71 words
A tachometer as in claim 6 wherein: said impedance means comprises a plurality of substantially equal-valued timing components, one of which is connected between said multivibrator stages, and adjusts said tachometer for a selected minimum number of spark discharges per motor revolution; and said adjusting means comprises means for switching additional ones of said equal-valued timing components into and out of connected relationship between said multivibrator stages one at a time.
Claim 9
Dependent Claim
145 words
A tachometer as in claim 7 wherein: said timing components are capacitors; means are arranged so that the connected ones of said capacitors are normally charged; means connect said second multivibrator stage to be on only when said connected capacitors are charged, and to turn off said first multivibrator stage when said second stage is on; means are connected so that, upon turning on in response to a spark-discharge-representing pulse, said first stage discharges said connected capacitors to turn off said second stage; means are connected to latch said first stage on when said second stage is off; means cooperate with said capacitors after said discharge to recharge said capacitors over an interval exceeding the duration of said spark-discharge-representing pulse; and means are connected to turn said second stage back on whereby to turn off said first stage at the end of said recharging interval.
Claim 10
Dependent Claim
25 words
A tachometer as in claim 8 wherein said adjusting means comprises: means for switching one or more of said capacitors in series with each other.
Claim 11
Dependent Claim
23 words
A tachometer as in claim 9 wherein said adjusting means further comprises: means for switching at least two of said capacitors in parallel.
Claim 12
Dependent Claim
83 words
A tachometer as in claim 10 wherein: said impedance means comprises a first group of at least one of said capacitors in series between a first set of at least two terminals, and a second group of at least two of said capacitors alternately interspersed in series with a second set of at least two terminals; and said adjusting means comprises connecting means for selectively connecting at least one of said terminals of said first set to respective terminals of said second set.
Claim 13
Dependent Claim
37 words
A tachometer as in claim 11 wherein: said connecting means is operable to put at least two of said capacitors in parallel and said parallel capacitors simultaneouslY in series with at least one other of said capacitors
Claim 14
Dependent Claim
25 words
A tachometer as in claim 5 further comprising: a single adjustable component connected to said visual indicating means to calibrate said tachometer at any adjustment.
Claim 15
Dependent Claim
22 words
A tachometer as in claim 13 wherein: said single adjustable component is an adjustable resistance in series with said visual indicating means.
Claim 16
Dependent Claim
38 words
A tachometer of the type described in claim 1 wherein said threshold R.F. detector includes an abruptly variable impedance element; and wherein the impedance of said element varies abruptly in response to the detection of said radiated energy.
Claim 17
Dependent Claim
35 words
A tachometer of the type described in claim 1 wherein at least virtual R.F. antenna means for picking up said radiated energy is coupled to said threshold detector and is mounted on said tachometer support.
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) | 1974-08-23 | 1975-02-22 | 1975-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-23 | 1979-02-22 | 1979-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-23 | 1983-02-22 | 1983-08-24 | $7700.00 | Window Closed / Lapsed |