CAPACITIVE PICK-UP MEANS FOR AN ELECTRICAL TACHOMETER

• US 3,686,569 A
• Filed: 05/01/1970
• Issued: 08/22/1972
• Est. Priority Date: 05/01/1970
• Status: Expired due to Term

• Current Assignee: Tage S. Neilsen
• Original Assignee: Tage S. Neilsen
• Inventors: Neilsen, Tage S.
• Primary Examiner(s): Rolinec, Rudolph V.
• Assistant Examiner(s): Karlsen, Ernest F.
• Application Number:
  US05/033,827
• Time in Patent Office: 844 Days
• Field of Search: 324/17,18,126,149,72,72.5,169,170
• US Class Current: 324/126
• CPC Class Codes: G01P 3/4807 by using circuits for the detection of the pulses delivered by the ignition system of an internal combustion engine
• CPC Class Codes: G01P 3/484 delivered by contact-making switches

Abstract

Herein described is an electrical tachometer which is responsive to electrical signals applied to selected spark plug wire of an automobile. The contact comprises a capacitive coupling contact which is wrapped around the exterior insulation of the spark plug wire. A clamp-on arrangement of the capacitive coupling contact includes a pair of contactor clips which are secured to the outer wire and held by an outer shield to shield, the signals picked up by the capacitive connections from outside noise environment. Electronic circuitry is responsive to the signals received by the capacity contactors and includes a signal shaping network to provide the necessary signal-to-noise discrimination. The relatively noise-free signal is then converted to a D.C. signal which is then applied to a meter.

Claims

1. A device for capacitively coupling an electrical connection to an insulated wire comprising:

a thin semitubular electrical contact adapted to be disposed about the outer surface of the insulated wire, said contact being coupled to the electrical connection for capacitively coupling the electrical connection to the insulated wire;

a first semicircular insulative member having a first longitudinal groove therein adapted to receive the insulated wire, said first member having a recess which communicates with said groove to receive said semitubular electrical contact;

a second semicircular insulative member including a second longitudinal groove adapted to receive the insulated wire, said first and second semicircular insulative members adapted to cooperate to substantially completely encase the insulated wire; and

means for securing said first and second members together, said means including a metal semitubular element to substantially cover said first member to shield the capacitive coupling from outside noises, said means also includes fastening means to contact said second member and bind such to said first member.

2. The device as defined in claim 1 wherein:

a lead wire attached to said contact; and

said second member including a recess on its exterior surface thereof which is adapted to receive an enlarged connection portion upon said lead wire, said enlarged connection portion adapted to be coupled to an electrical ground reference.

3. The device as defined in claim 2 wherein:

said fastening means includes longitudinal ridge means located upon said second member, said metal semitubular element including inwardly extending lip means, said lip means being adapted to engage said ridge means when said element is disposed over said first member.

4. The device as defined in claim 3 wherein:

said metal semitubular element includes stop means located adjacent one end thereof, said stop means being adapted to abut an edge of said first member, said element including a spring biased clip located adjacent the free end of said element opposite said stop means, with said element disposed about said first member and said stop means being in contact with one edge of said first member said spring biased clip being movable inwardly to contact the opposite edge of said firSt member.