Rechargeable vacuum with reduced AC voltage
View Patent ↗A motor is disclosed that operates on either AC outlet power or DC battery power with decreased power drop when switching between AC and DC power. The AC power to the motor may be stepped down by using a clipper circuit, while the DC power supplied to the motor may be increased by switching motor field windings from a series wound circuit to a parallel wound circuit. The motor may be used in a vacuum motor embodiment, or in other consumer devices that utilize electric motors.
1. An electric motor comprising:
a rotor having a single armature coil and at least one pair of electrical contacts, wherein each pair of electrical contacts defines the ends of a single continuous circuit of the rotor armature coil;
a stator having a first and a second field coil, wherein the first field coil includes a first end and second end, the second field coil includes a first end and second end, and the first and second field coils are positioned on opposite sides of the stator;
a first brush and a second brush positioned on opposite sides of the stator wherein the first and second brushes make electrical connections to the electrical contacts on the rotor as the rotor rotates with respect to the stator; and
a switch arranged to connect a parallel field coil circuit to a source of DC power and arranged to connect a series field coil circuit to a source of AC power;
wherein the series field coil circuit comprises the first end of the first field coil connected to the first brush, the first end of the second field coil connected to the second brush, the second end of the first field coil connected to a first terminal of the switch and the second end of the second field coil connected to a second terminal of the switch; and
the parallel field coil circuit comprises the first end of the first field coil connected to a first end of the second field coil, a second end of the first field coil connected to a second end of the second field coil and the second motor brush, and a third terminal of the switch connected to the first end of the first field coil and a fourth terminal of the switch connected to the first brush.
2. The electric motor of claim 1 , wherein a clipper circuit is connected across the AC power source and the clipper circuit connects the AC power source to the series field coil circuit during a predetermined period of a half cycle of the AC power source.
3. The electric motor of claim 2 , wherein the clipper circuit is connected to a rectifying circuit and the rectifying circuit is connected to a battery.
4. The electric motor of claim 3 , wherein the DC power source comprises the battery.
5. The electric motor of claim 2 , wherein the clipper circuit comprises a DIAC, a TRIAC, a first resistor, a second resistor, and a capacitor, and wherein the TRIAC is connected between a terminal of the AC power source and the first field coil circuit, and wherein the first resistor, the second resistor, and the capacitor are connected in a series combination, the series combination further connected in parallel with the TRIAC, and wherein the DIAC is connected between the gate of the TRIAC and the junction of the second resistor and the capacitor.
6. The electric motor of claim 5 , wherein the second resistor is a variable resistor.
7. The electric motor of claim 5 , wherein the clipper circuit further comprises a snubber circuit connected in parallel with the TRIAC.
8. The electric motor of claim 7 , wherein the snubber circuit comprises a resistor and a capacitor connected in series.
9. A method of operating an electric motor that includes a series wound field coil circuit having a first end of a first field coil connected to a first motor brush, a first end of a second field coil connected to a second motor brush, and an AC power supply connected between a second end of the first field coil and a second end of the second field coil, and a parallel wound field coil circuit having a first end of the first field coil connected to a first end of the second field coil, a second end of the first field coil connected to a second end of the second field coil and the first motor brush, and a DC power supply connected between the second motor brush and the first end of the first field coil, wherein the first and second motor brush contact a single continuous armature coil circuit;
the method comprising:
switching to the series wound field coil circuit when an AC power supply is used and to the parallel wound field coil circuit when a DC power supply is used.
10. The method of claim 9 , further comprising the step of connecting a clipper circuit across the AC power supply.
11. A vacuum cleaner comprising:
a housing with a suction opening;
a debris collection unit;
an AC power cord;
a battery; and
an electric motor comprising:
a rotor having at least two electrical contacts that define the ends of a single armature coil circuit;
a stator having a first and a second field coil, wherein the first field coil includes a first end and a second end, the second field coil includes a first end and a second end, and the first and second field coils are positioned on opposite sides of the stator;
a first brush and a second brush positioned on opposite sides of the stator wherein the first and second brush make electrical connections to the electrical contacts as the rotor rotates with respect to the stator; and
a switch that connects a power source to one of a series field coil circuit and a parallel field coil circuit, wherein the power source includes a first terminal and a second terminal;
wherein the series field coil circuit comprises the first end of the first field coil connected to the first brush, the first end of the second field coil connected to the second brush, the second end of the first field coil connected to the first terminal of the power source and the second end of the second field coil connected to the second terminal of the power source; and
the parallel field coil circuit comprises the first end of the first field coil connected to a first end of the second field coil, a second end of the first field coil connected to a second end of the second field coil and the second motor brush, and the power source connected between the first end of the first field coil and the first brush.
12. The vacuum cleaner of claim 11 , wherein the switch connects the AC power cord to the series field coil circuit and the switch further connects the battery to the parallel field coil circuit.
13. The vacuum cleaner of claim 11 , further comprising a clipper circuit connected across the AC power cord, wherein the clipper circuit connects the AC power cord to the series field coil circuit during a predetermined period of a half cycle of the AC power source.
14. The vacuum cleaner of claim 13 , wherein the clipper circuit is connected to a rectifying circuit and the rectifying circuit is connected to the battery.
15. The vacuum cleaner of claim 14 , wherein the clipper circuit and rectifying circuit provide power to charge the battery when the AC power cord is connected to an AC power supply.
16. The electric motor of claim 11 , wherein the switch comprises a four-pole, double throw switch.
17. The electric motor of claim 11 , wherein the switch comprises a four pole single throw switch.
18. The electric motor of claim 17 , further comprising a second switch for connecting one of the battery and AC power cord to the four pole single throw switch.