Portable electric tool vacuum cleaner control

• US 6,044,519 A
• Filed: 03/21/1997
• Issued: 04/04/2000
• Est. Priority Date: 12/07/1995
• Status: Expired due to Term

• Current Assignee: Emerson Electric Company
• Original Assignee: Emerson Electric Company
• Inventors: Hendrix, George E.
• Primary Examiner(s): MOORE, CHRISTOPHER K
• Application Number:
  US08/821,327
• Time in Patent Office: 1,110 Days
• Field of Search: 15/301, 15/319, 15/339, 15/314
• US Class Current: 15/319
• CPC Class Codes: A47L 7/0095 Suction cleaners or attachments adapted to collect dust or waste from power tools
• CPC Class Codes: A47L 9/2805 Parameters or conditions being sensed
• CPC Class Codes: A47L 9/2842 Suction motors or blowers
• CPC Class Codes: A47L 9/2857 User input or output elements for control, e.g. buttons, switches or displays

Abstract

A portable electric tool vacuum cleaner control to permit use of a vacuum cleaner independent of and in conjunction with a portable electric tool is disclosed. The vacuum cleaner control includes a motor control circuit and a motor for operating the vacuum cleaner. An electrical outlet is provided on the vacuum cleaner, which is connected to the vacuum cleaner motor control circuit, to enable a portable electric tool to be plugged into the vacuum cleaner electrical outlet. A three position on/off/automatic switch is provided on the vacuum cleaner for operating the vacuum cleaner motor control circuit to enable independent operation of the vacuum cleaner or joint operation of the portable electric tool in conjunction with the vacuum cleaner, as desired.

Claims

1. A vacuum assembly adapted for use with an electric tool, the vacuum assembly comprising:

a vacuum motor having a first motor terminal adapted to be coupled to a source of AC power and a second terminal;

a gated bi-directional semiconductor switch having a first terminal coupled to the second terminal of the vacuum motor and a second terminal adapted to be coupled to the source of AC power so as to provide a path for current to flow from the source of AC power through the vacuum motor when the switch is rendered conductive in response to the application of a current pulse to the gate of the switch;

a current sensor for detecting the flow of electric current to the electric tool and generating a DC voltage signal having a magnitude corresponding to the magnitude of the current flowing to the electric tool; and

circuitry for applying the current pulse to the gate of the switch to render the switch conductive while the DC voltage signal exceeds a predetermined value, wherein the current providing the current pulse flows through the vacuum motor.

5. The vacuum assembly of claim 1 wherein the gated bi-directional semiconductor switch is a triac.

2. A vacuum assembly adapted for use with an electric tool, the vacuum assembly comprising:

a vacuum motor having a first motor terminal adapted to be coupled to a source of AC power and a second terminal;

a gated bi-directional semiconductor switch having a first terminal coupled to the second terminal of the vacuum motor and a second terminal adapted to be coupled to the source of AC power so as to provide a path for current to flow from the source of AC power through the vacuum motor when the switch is rendered conductive in response to the application of a current pulse to the gate of the switch;

a current sensor for detecting the flow of electric current to the electric tool and generating a DC voltage signal having a magnitude corresponding to the magnitude of the current flowing to the electric tool, wherein the current sensor comprises;

a transformer having an input connected in series with the line providing power to the electric tool and an output that provides a signal corresponding to the current flowing to the electric tool; and

a rectifier, the rectifier having an input coupled to the output of the transformer and an output that provides a DC signal having a magnitude that corresponds to the output magnitude of the transformer; and

circuitry for applying a current pulse to the gate of the switch to render the switch conductive while the DC voltage signal exceeds a predetermined value.

3. The vacuum assembly of claim 2 wherein the rectifier is a diode.

4. The vacuum assembly of claim 2 further comprising a capacitor coupled to the output of the rectifier, wherein the output of the capacitor is the DC signal and wherein the capacitor is sized such that the DC signal at the output of the capacitor remains above a predetermined voltage level for a predetermined time period after the flow of electric current to the power tool is halted.

6. A vacuum assembly adapted for use with an electrical tool, the vacuum assembly comprising:

a vacuum motor having a first motor terminal adapted to be coupled to a source of AC power and a second terminal;

a gated bi-directional semiconductor switch having, a first terminal coupled to the second terminal of the vacuum motor, and a second terminal adapted to be coupled to the source of AC power so as to provide a path for current to flow from the source of AC power through the vacuum motor when the switch is rendered conductive in response to the application of a current pulse to the gate of the switch;

a current sensor for detecting the flow of electric current to the electric tool and generating a DC voltage signal having a magnitude corresponding to the magnitude of the current flowing to the electric tool; and

circuitry for applying a current pulse to the gate of the switch to render the switch conductive while the DC voltage signal exceeds a predetermined value, wherein the circuitry for applying a current pulse to the gate of the switch comprises;

a full wave rectifier having first and second AC inputs adapted to receive AC power and first and second DC outputs adapted to provide DC power, the first AC input being electrically coupled to the first terminal of the switch and the second AC input being electrically coupled to the gate of the switch;

a semiconductor switching device coupled across the DC output terminals of the full wave rectifier, the semiconductor switching device having a gate adapted to receive the DC voltage signal; and

an impedance circuit having a first terminal coupled to the second AC input of the full wave rectifier and a second terminal coupled to the second terminal of the switch.

7. The vacuum assembly of claim 6 wherein the current sensor comprises:

a transformer having an input connected in series with the line providing power to the electric tool and an output that provides a signal corresponding to the current flowing to the electric tool; and

a rectifier, the rectifier having an input coupled to the output of the transformer and an output that provides a DC signal having a magnitude that corresponds to the peak output magnitude of the transformer.

8. A method of energizing a vacuum motor in response to the energization of an electric tool, the vacuum motor being coupled to a source of electric power through a gated power semiconductor device, the method comprising the acts of:

detecting the flow of electric current to the electric tool and generating a DC voltage signal having a magnitude corresponding to the magnitude of the current flowing to the electric tool; and

establishing a current path from the source of electric power through the vacuum motor to the gate of the gated power semiconductor device when the DC voltage exceeds a predetermined voltage level to render the gated power semiconductor device conductive and to energize the vacuum motor.

10. The method of claim 8 further comprising the step of maintaining the magnitude of the DC voltage signal above a predetermined minimum level for a predetermined period of time after the electric tool is de-energized.

9. A method of energizing a vacuum motor in response to the energization of an electric tool, the vacuum motor being coupled to a source of electric power through a gated power semiconductor device, the method comprising the acts of:

detecting the flow of electric current to the electric tool and generating a DC Voltage signal having a magnitude corresponding to the magnitude of the current flowing to the electric tool;

establishing a current path between a source of electric power and the gate of the gated power semiconductor device when the DC voltage exceeds a predetermined voltage level to render the gated power semiconductor device conductive and to energize the vacuum motor; and

wherein AC power is applied to the electric tool when the tool is energized and wherein the act of detecting the flow of electric current to the electric tool and generating the DC voltage signal having a magnitude corresponding to the magnitude of the current flowing to the electric tool comprises the acts of;

using a transformer to generate a low-voltage AC signal that is substantially in-phase with the AC power being applied to the electric tool, but that has a peak voltage magnitude that is substantially less than the peak voltage magnitude of the AC power being applied to the electric tool; and

rectifying and filtering the low-voltage AC signal to provide the DC voltage signal.

11. An improved vacuum assembly for use with a portable electric tool comprising:

a vacuum motor;

means for detecting energization of the portable electric tool and providing an output electric signal indicating that the portable electrical tool is energized;

means for receiving the output electric signal and generating DC power to apply a current pulse flowing through the vacuum motor; and

semiconductor means coupled to receive the current pulse and to energize the vacuum motor.