Braking and control circuit for electric power tools

A drill press comprising:

• a housing;
• a base connected with said housing and supporting said drill press on a workpiece, said base being selectively connected with the workpiece;
• an electric motor supported by said housing and operable to drive a tool element, said motor including a stator supported by said housing, and a shaft rotatably supported by said housing, said motor being connectable with a power source;
• a spindle connected with said shaft for rotation with said shaft, said spindle supporting a tool bit engageable with the workpiece;
• braking and control means for controlling and braking said motor, said braking and control means including
• switch means electrically connected with said motor, and
• control means electrically connected with said switch means and operable to output a control signal to control said switch means to brake the motor;
• and
• breakaway sensing means electrically connected with said control means and operable to output a breakaway signal to said control means if said base brakes away from the workpiece so that said control means outputs the control signal to said switch means to brake said motor.

A power tool comprising:

• a housing;
• an electric motor supported by said housing and operable to drive a tool element, said motor including a stator supported by said housing, and a shaft rotatably supported by said housing, said motor being connectable with a power source;
• a spindle connected with said shaft for rotation with said shaft, said spindle supporting a tool element engageable with a workpiece;
• braking and control means for controlling and braking said motor, said braking and control means including
• switch means electrically connected with said motor, and
• control means electrically connected with said switch means and operable to output a control signal to control said switch means to brake the motor;
• and
• binding sensing means electrically connected with said control means and operable to output a binding signal to said control means if the tool element binds on the workpiece so that said control means outputs the control signal to said switch means to brake said motor.

In a power tool, a method for braking and controlling an electric motor, the motor including a housing, a stator supported by the housing, and a shaft rotatably supported by the housing, the motor being selectively connected with an alternating current power source to rotatably drive the shaft, said method comprising:

• (a) providing a braking and control circuit including a first switch for selectively connecting the motor to the power source, a second switch electrically connected in parallel with the motor, and a control circuit including a microcontroller electrically connected with at least one of the first switch and the second switch;
• (b) outputting a control signal from the microcontroller to control at least one of the first switch and the second switch to brake the motor said outputting act including outputting the control signal when the alternating current is in a start point phase angle;
• (c) programming the microcontroller to optimize braking of the motor, said programming act including programming the microcontroller to select the braking start point corresponding to a start point phase angle of the alternating current;
• and
• (d) providing to the control circuit a current signal representing the alternating current.

A software program for controlling the braking of a motor in a power tool, said software program controlling the motor by:

• receiving a signal representing an alternating current supplied to the motor from a power source;
• receiving a trigger signal to trigger braking of the motor;
• evaluating the alternating current signal to determine a phase angle of the alternating current;
• and
• outputting a control signal to control a switch to brake the motor when the current signal represents a selected brake start point phase angle.

A braking and control circuit for an electric motor, the motor including a housing, a stator supported by the housing, and a shaft rotatably supported by the housing, wherein the stator is selectively connected with a power source to rotatably drive the shaft, said braking and control circuit comprising:

• a first switch for selectively disconnecting the motor from the power source;
• a second switch electrically connected across the motor;
• and
• a control circuit electrically connected with said first switch and said second switch and operable to output a first control signal to said first switch and a second control signal to said second switch to brake the motor;
• wherein said control circuit includes a microcontroller electrically connected with said first switch and said second switch, said microcontroller being operable to output the first control signal and the second control signal, wherein said microcontroller is programmable to optimize braking of the motor;
• wherein the motor is braked in a stopping time, and wherein said microcontroller is programmable to change the stopping time of the motor.

A braking and control circuit for an electric motor, the motor including a housing, a stator supported by the housing, and a shaft rotatably supported by the housing, wherein the stator is selectively connected with a power source to rotatably drive the shaft, said braking and control circuit comprising:

• a first switch for selectively disconnecting the motor from the power source;
• a second switch electrically connected across the motor;
• and
• a control circuit electrically connected with said first switch and said second switch and operable to output a first control signal to said first switch and a second control signal to said second switch to brake the motor;
• wherein said control circuit includes a microcontroller electrically connected with said first switch and said second switch, said microcontroller being operable to output the first control signal and the second control signal, wherein said microcontroller is programmable to optimize braking of the motor;
• wherein the motor is braked with a braking force, and wherein said microcontroller is programmable to change the braking force applied to the motor.

A braking and control circuit for an electric motor, the motor including a housing, a stator supported by the housing, and a shaft rotatably supported by the housing, wherein the stator is selectively connected with a power source to rotatably drive the shaft, said braking and control circuit comprising:

• a first switch for selectively disconnecting the motor from the power source;
• a second switch electrically connected across the motor;
• and
• a control circuit electrically connected with said first switch and said second switch and operable to output a first control signal to said first switch and a second control signal to said second switch to brake the motor;
• wherein said control circuit includes a microcontroller electrically connected with said first switch and said second switch, said microcontroller being operable to output the first control signal and the second control signal, wherein said microcontroller is programmable to optimize braking of the motor;
• wherein the power source is an alternating current power source, wherein said control circuit receives a current signal representing a voltage of the alternating current, and wherein said microcontroller is programmable to output at least one of the first control signal and the second control signal at a point in the alternating current so that a desired voltage is supplied to brake the motor.

In a power tool, a method for braking and controlling an electric motor, the motor including a housing, a stator supported by the housing, and a shaft rotatably supported by the housing, the motor being selectively connected with a power source to rotatably drive the shaft, said method comprising:

• (a) providing a braking and control circuit including a first switch for selectively connecting the motor to the power source, a second switch electrically connected in parallel with the motor, and a control circuit electrically connected with the first switch and the second switch;
• and
• (b) outputting a first control signal from the control circuit to control the first switch and a second control signal from the control circuit to control the second switch to brake the motor;
• and
• wherein the control circuit includes a microcontroller electrically connected with the first switch and the second switch, wherein (b) includes outputting the first control signal and the second control signal from the microcontroller, wherein said method further comprises:
• (c) programming the microcontroller to optimize braking of the motor;
• wherein the motor is braked in a stopping time, and wherein (c) includes programming the microcontroller to change the stopping time of the motor.

In a power tool, a method for braking and controlling an electric motor, the motor including a housing, a stator supported by the housing, and a shaft rotatably supported by the housing, the motor being selectively connected with a power source to rotatably drive the shaft, said method comprising:

• (a) providing a braking and control circuit including a first switch for selectively connecting the motor to the power source, a second switch electrically connected in parallel with the motor, and a control circuit electrically connected with the first switch and the second switch;
• and
• (b) outputting a first control signal from the control circuit to control the first switch and a second control signal from the control circuit to control the second switch to brake the motor;
• and
• wherein the control circuit includes a microcontroller electrically connected with the first switch and the second switch, wherein (b) includes outputting the first control signal and the second control signal from the microcontroller, wherein said method further comprises:
• (c) programming the microcontroller to optimize braking of the motor;
• wherein the motor is braked in a stopping time, and wherein (c) includes programming the microcontroller to change the braking force applied to the motor.

In a power tool, a method for braking and controlling an electric motor, the motor including a housing, a stator supported by the housing, and a shaft rotatably supported by the housing, the motor being selectively connected with a power source to rotatably drive the shaft, said method comprising:

• (a) providing a braking and control circuit including a first switch for selectively connecting the motor to the power source, a second switch electrically connected in parallel with the motor, and a control circuit electrically connected with the first switch and the second switch;
• and
• (b) outputting a first control signal from the control circuit to control the first switch and a second control signal from the control circuit to control the second switch to brake the motor;
• wherein the control circuit includes a microcontroller electrically connected with the first switch and the second switch, wherein (b) includes outputting the first control signal and the second control signal from the microcontroller, wherein said method further comprises the act of:
• (c) programming the microcontroller to optimize braking of the motor;
• wherein the power source is an alternating current power source, and wherein said method further comprises the act of:
• (d) providing to the control circuit a current signal representing a voltage of the alternating current;
• and wherein (c) includes programming the microcontroller to output at least one of the first control signal and the second control signal at a point in the alternating current so that a desired voltage is supplied to brake the motor.

A software program for controlling the braking of a motor in a power tool, said software program controlling the motor by:

• (a) receiving a signal;
• (b) outputting a first control signal to control a first switch to brake the motor;
• and
• (c) outputting a second control signal to a second switch to brake the motor;
• wherein the received signal is a signal representing an alternating current supplied to the motor from a power source, wherein said software program further controls the motor by, before (b):
• (d) receiving a trigger signal to trigger braking of the motor;
• and
• (e) evaluating the alternating current signal to determine the phase angle of the alternating current;
• wherein (b) includes outputting the control signal when the current signal represents a selected brake start point phase angle.