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Digital ignition spark timing angle control with read only memory

  • US 4,009,699 A
  • Filed: 01/19/1976
  • Issued: 03/01/1977
  • Est. Priority Date: 01/19/1976
  • Status: Expired due to Term
First Claim
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1. An ignition spark timing control system for use with a spark ignition internal combustion engine and a sequence control arrangement comprising:

  • a read only memory pre-programmed to produce an output binary signal representation of predetermined ignition spark timing angle based upon the instantaneous value of both of two selected engine operating parameters at each of a plurality of respective selected points within the range of values in response to respective input address signals whereby over the range of values of the two selected engine operating parameters the read only memory generates a three-dimensional surface of ignition spark timing angles based upon the two selected engine parameter values;

    means for producing input address signals for said read only memory in response to binary signal representations of instantaneous values of said selected two engine operating parameters;

    means for applying said input address signals to said read only memory whereby the binary signal representation of an ignition spark timing angle is produced by said read only memory in response to each of said input address signals; and

    means effective to vary the binary signal representations of the ignition spark timing angles as retrieved from said read only memory in accordance with engine manifold vacuum in substantial inverse proportion to atmospheric pressure whereby said three-dimensional surface generated by said read only memory is tilted about a selected engine parameter value as an axis in an amount substantially inversely proportional to actual atmospheric pressure.

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