Variable speed control switch for direct current electric power tools
AssigneeEaton Corporation
InventorsJackson Henry Smith, Michael Thomas Little
Life of this patent
Estimating the term…
Abstract
A motor control circuit for a power tool includes a function switch which has a first battery contact, a speed control contact, a bypass contact and, a second battery contact connected in that order in a line. The function switch also has a movable contact which sequentially connects the first battery contact to the bypass contact, the speed control contact to the second battery contact, and the bypass contact to the second battery contact. A solid state switch has conduction path connecting the speed control contact to the second motor terminal wherein the conduction path is controlled in response to an oscillator signal.
Claims17
A variable speed control for a DC electric motor connected to a solid state switching device for powering by a battery, said variable speed control having a motor function switch which comprises:
- a first battery contact for connection to a first terminal of the battery;
- a speed control contact adjacent to the first battery contact and for applying electric current to the solid state switching device;
- a bypass contact adjacent to the speed control contact and for connection directly to the DC electric motor;
- a second battery contact adjacent to the bypass contact and for connection to a second terminal of the battery;
- and
- a movable contact which moves in one direction from a first position at which the moveable contact connects the first battery contact to the bypass contact to a second position at which the moveable contact connects the speed control contact to the second battery contact, and then to a third position at which the moveable contact connects the bypass contact to the second battery contact.
A variable speed control for a DC electric motor connected to a solid state switching device for powering by a battery, said variable speed control comprises:
- a user operable member having a contact carrier;
- a first battery contact for connection to a first terminal of the battery;
- a speed control contact adjacent to the first battery contact and for applying electric current to the solid state switching device;
- a bypass contact adjacent to the speed control contact and for connection directly to the DC electric motor;
- a second battery contact adjacent to the bypass contact and for connection to a second terminal of the battery;
- and
- a movable contact attached to the contact carrier for movement in one direction from a first position at which the moveable contact connects the first battery contact to the bypass contact to a second position at which the moveable contact connects the speed control contact to the second battery contact, and then to a third position at which the moveable contact connects the bypass contact to the second battery contact.
A variable speed control for a DC electric motor powered by a battery, the variable speed control comprising:
- first and second battery terminals for connecting the battery to the variable speed control;
- first and second motor terminals for connecting the motor to the variable speed control;
- a motor function switch having a first battery contact connected to the first battery terminal and to the first motor terminal, a speed control contact adjacent to the first battery contact, a bypass contact adjacent to the speed control contact and connected to the second motor terminal, a second battery contact adjacent to the bypass contact and connected to the second battery terminal, and a bridge contact moveable from a first position at which the bridge contact connects the first battery contact to the bypass contact to a second position at which the bridge contact connects the speed control contact to the second battery contact, and then to a third position at which the bridge contact connects the bypass contact to the second battery contact;
- an oscillator that produces a signal;
- and
- a solid state switching device coupled to the oscillator and having a conduction path connecting the speed control contact to the second motor terminal wherein the conduction path is rendered conductive and non-conductive in response to the signal.
A variable speed control for a DC electric motor powered by a battery, the variable speed control comprising:
- first and second battery terminals for connecting the battery to the variable speed control;
- first and second motor terminals for connecting the motor to the variable speed control;
- and
- a motor function switch including:
- (a) a first battery contact for connection to a first terminal of the battery,
- (b) a second battery contact for connection to a second terminal of the battery,
- (c) a speed control contact, located between the first battery contact and the second battery contact, for applying electric current to the solid state switching device,
- (d) a bypass contact, located between the speed control contact and the second battery contact, for connection directly to the DC electric motor, and
- (e) a bridge contact movable from a first position at which the moveable contact connects the first battery contact to the bypass contact to a second position at which the bridge contact connects the speed control contact to the second battery contact, and then to a third position at which the bridge contact connects the bypass contact to the second battery contact,
- wherein the first position is an off position which provides a dynamic brake connection for the DC electric motor.
Dependencies are inferred from the claim text.