Handheld grinder with a brushless electric motor

A handheld power tool comprising:

• an elongated housing having a grip portion that is shaped to be grasped by a user;
• a brushless electric motor residing in the elongated housing and having a drive shaft;
• an end tool;
• an output shaft having a first end and a second end, the first end of the output shaft being connected to the drive shaft of the brushless electric motor and the second end of the output shaft being connected to the end tool to impart motion to the end tool when the brushless electric motor rotates;
• a fan driven by the brushless electric motor for circulating air through the elongated housing when the brushless electric motor is operating;
• and
• a circuit board residing in the elongated housing and having a longitudinal axis that is aligned with a longitudinal axis of the elongated housing, the circuit board having thereon
• a rectifier configured to receive power from an alternating current (AC) power source and operable to convert an alternating current to a direct current,
• a switching arrangement having a plurality of motor switches connected electrically between the rectifier and the brushless electric motor and operates to deliver the direct current from the rectifier to the brushless electric motor,
• a capacitor connected electrically between the rectifier and the switching arrangement, wherein the capacitor is coupled in parallel across the rectifier,
• a driver circuit interfaced with the motor switches and operable to control switching operation of the motor switches,
• a controller interfaced with the driver circuit and operable to provide pulse width modulated (PWM) signals to the driver circuit for driving the brushless electric motor, and
• a power switch connected electrically between the rectifier and the driver circuit and operable by a tool operator to selectively energize the driver circuit and thereby power on the end tool.

A handheld grinder comprising:

• an elongated housing having a grip portion that is shaped to be grasped by a user;
• a brushless electric motor residing in the elongated housing and having a drive shaft;
• a grinding disk;
• an output shaft having a first end and a second end, the first end of the output shaft being connected to the drive shaft of the brushless electric motor and the second end of the output shaft being connected to the grinding disk to impart rotary motion to the grinding disk when the brushless electric motor rotates;
• and
• a circuit board residing in the housing, the circuit board having a longitudinal axis and a longitudinal axis of the circuit board being aligned with the longitudinal axis of the elongated housing, the circuit board having thereon
• a first set of solder points soldered towards a first end of the circuit board for receiving alternating current (AC) power from an AC power source,
• a rectifier soldered adjacent to the first set of solder points, the rectifier being configured to receive power from the AC power source through the first set of solder points and operable to convert an alternating current to a direct current,
• a switching arrangement having a plurality of motor switches interposed between the rectifier and the brushless electric motor and operates to deliver the direct current from the rectifier to the brushless electric motor,
• a first heat sink disposed on top of the switching arrangement,
• a capacitor interposed between the rectifier and the switching arrangement, wherein the capacitor is coupled in parallel across the rectifier,
• a second heat sink interposed between the rectifier and the capacitor and abutting the rectifier,
• a driver circuit interfaced with the motor switches and operable to control switching operation of the motor switches,
• a second set of solder points soldered proximate to the driver circuit and being shaped to receive wiring connections from the brushless electric motor, and
• a power switch soldered towards a second end of the circuit board that is opposite from the first end, the power switch being connected electrically between the rectifier and the driver circuit and operable by a tool operator to selectively energize the driver circuit and thereby power on the grinding disk.