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Dual speed rotary vane pump

  • US 4,207,031 A
  • Filed: 03/29/1978
  • Issued: 06/10/1980
  • Est. Priority Date: 03/29/1978
  • Status: Expired due to Term
First Claim
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1. A dual speed vacuum pump comprising in combination:

  • a mechanical rotary vacuum pump;

    input terminals for a source of electrical power;

    a two speed electrical motor directly connected to said pump for driving same, said motor having a first and a second plurality of windings which, when connected to said input terminals, cause said motor to rotate at a first speed and at a second speed respectively, with said second speed being lower than said first speed; and

    control circuit means for connecting said motor to said input terminals to cause said motor to rotate at said first speed for a predetermined period of time and at said second speed after said predetermined period of time, said control circuit means including;

    a first plurality of normally open switching contacts for connecting said first plurality of windings to said input terminals, a second plurality of normally open switching contacts for connecting said second plurality of windings to said input terminals, a first relay coil for closing said first plurality of normally open switching contacts when energized, a second relay coil for closing said second plurality of normally open switching contacts when energized, and timing means, responsive to an input signal to said control circuit means, for causing only said first relay coil to be energized for said predetermined period of time and for thereafter deenergizing said first relay coil and for energizing said second relay coil.

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