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Protective control for vehicle starter and electrical systems

  • US 4,209,816 A
  • Filed: 07/07/1978
  • Issued: 06/24/1980
  • Est. Priority Date: 07/07/1978
  • Status: Expired due to Term
First Claim
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1. A protective control for the starter system of an engine which is cranked by a starter motor, comprising:

  • starter relay means in circuit with said starter motor;

    frequency selective means responsive to engine RPM to automatically open said starter relay means above a predetermined threshold set frequency corresponding to a designated RPM level, to prevent cranking of said engine thereabove,said frequency selective means including hysteresis means to prevent reclosing of said starter relay means until engine RPM drops to a lower level corresponding to a reset frequency less than said threshold set frequency, whereby to prevent recranking of said engine until engine RPM drops to said lower level;

    transducer means responsive to engine speed to produce a signal whose frequency corresponds to engine RPM,said frequency selective means having an input for receiving said transducer signal and an output controlling said starter relay means;

    wherein said transducer signal, upon reaching said threshold set frequency, causes said output to switch states and also activates said hysteresis means to lower the frequency value necessary to cause switching of said output back to its original state;

    said transducer means comprising an AC signal generator and input waveshaping means for receiving the AC signal and delivering a clear waveshape signal to said input of said frequency selective means;

    said frequency selective means comprising a programmable frequency switch having an input receiving said transducer signal and a pair of opposite state outputs one of which is connected to said starter relay means and the other of which is connected to a hysteresis network, such that when the frequency of said transducer signal at said input reaches said threshold value, said outputs switch states such that said one output causes opening of said starter relay means and said other output causes said hysteresis network to lower the value of said threshold frequency down to said reset frequency;

    said hysteresis network comprising a capacitor which is floated when the other of said outputs is in the first mentioned of its states, and which is connected in circuit with said frequency switch when said other of said outputs switches to its second mentioned state.

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