US 4,366,425 AGranted

Timer-controlled speed changing device for electric fans

OwnerChou-Ming Sheninventor

Life of this patent

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Abstract

A timer-controlled speed changing device for electric fans comprising a timing switch operatively connected to a first speed changing circuit and a second speed changing circuit, for changing the speed of an electric fan from a pre-set speed with the first or second speed changing circuit to another pre-set speed with the second or first speed changing circuit after a predetermined time period set by the timing switch.

Claims6

Dependent claims

A timer-controlled speed changing device for an electric fan comprising:

a timing switch having a switching means and a timing means, said switching means being provided with a first contact terminal, a second contact terminal and a switch piece operable with said timing means, said switch piece being capable of coming into contact with said first or second contact terminal in association with the operation of said timing means;
a first electrical circuit comprising a field winding and operable to operate said electric fan when a voltage is supplied thereto, a plurality of taps drawn from said field winding, each tap being provided with a tap terminal, a first voltage control circuit, a first selector switch operable to selectively connect each said tap terminal with said first voltage control circuit through a capacitor means, said first voltage control circuit having a first variable resistor and a first semi-variable resistor connected in parallel with said first variable resistor, a resistor and a first auxiliary switch connected in series with said first variable resistor, said first voltage control circuit having one end connected to said first contact terminal of said switching means and the other end connected to a power source;
a triac circuit comprising a triac having a gate and first and second anodes, a diac having two leads and being respectively connected between said switch piece and said gate of said triac, an inductor having one end connected to said second anode of said triac and the other end connected to said power source, said first anode of said triac being connected to said first selector switch;
a second voltage control circuit having a second variable resistor and a second semi-variable resistor connected in parallel with said second variable resistor, a second resistor and a second selector switch connected in series with said second variable resistor, said second voltage control circuit having one end connected to said second contact terminal and the other end connected to a power source;
and, a protective circuit having a capacitor and resistor connected in series, said protective circuit having one end connected to said second voltage control circuit via a capacitor means and therefrom to said first selector switch, the other end of said protective circuit being connected to said power source.

2 more elements

A timer-controlled speed changing device for an electric fan comprising:

a timing switch having a switching means and a timing means, said switching means being provided with a first contact terminal, a second contact terminal and a switch piece operable with said timing means, said switch piece being capable of coming into contact with said first or second contact terminal in association with the operation of the said timing means;
a first electrical circuit having a field winding and operable to operate an electric fan when a voltage is supplied thereto, a plurality of taps drawn from said field winding, each tap being provided with a tap terminal, and a first selector switch connected with said first contact terminal and operable to selectively electrically connect each tap terminal with the said first contact terminal of the said switching means so as to select an operational speed of said electric fan;
and
a second electrical circuit provided with a second selector switch, connective with said second contact terminal, and a speed changing circuit connected with said field winding, the said second selector switch being operable to electrically selectively connect said speed changing circuit with the said second contact terminal of said switching means.

1 more element

Dependencies are inferred from the claim text.

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Abstract

A timer-controlled speed changing device for an electric fan comprising:

a timing switch having a switching means and a timing means, said switching means being provided with a first contact terminal, a second contact terminal and a switch piece operable with said timing means, said switch piece being capable of coming into contact with said first or second contact terminal in association with the operation of said timing means;
a first electrical circuit comprising a field winding and operable to operate said electric fan when a voltage is supplied thereto, a plurality of taps drawn from said field winding, each tap being provided with a tap terminal, a first voltage control circuit, a first selector switch operable to selectively connect each said tap terminal with said first voltage control circuit through a capacitor means, said first voltage control circuit having a first variable resistor and a first semi-variable resistor connected in parallel with said first variable resistor, a resistor and a first auxiliary switch connected in series with said first variable resistor, said first voltage control circuit having one end connected to said first contact terminal of said switching means and the other end connected to a power source;
a triac circuit comprising a triac having a gate and first and second anodes, a diac having two leads and being respectively connected between said switch piece and said gate of said triac, an inductor having one end connected to said second anode of said triac and the other end connected to said power source, said first anode of said triac being connected to said first selector switch;
a second voltage control circuit having a second variable resistor and a second semi-variable resistor connected in parallel with said second variable resistor, a second resistor and a second selector switch connected in series with said second variable resistor, said second voltage control circuit having one end connected to said second contact terminal and the other end connected to a power source;
and, a protective circuit having a capacitor and resistor connected in series, said protective circuit having one end connected to said second voltage control circuit via a capacitor means and therefrom to said first selector switch, the other end of said protective circuit being connected to said power source.

2 more elements