Brushless DC motor power tool with combined PCB design

#The present invention relates to brushless motor power tools.

#Power tool motors can generally be grouped into two categories: brushed motors and brushless motors. In a brushed motor, motor brushes make and break electrical connection to the motor due to rotation of the rotor. In a brushless motor power tool, such as power tool 100 of FIG. 1, switching elements are selectively enabled and disabled by control signals from a controller to selectively apply power from a power source to drive the brushless motor. The power tool 100 is a brushless hammer drill having a housing 102 with a handle portion 104 and motor housing portion 106. The power tool 100 further includes an output unit 107, torque setting dial 108, forward/reverse selector 110, trigger 112, battery interface 114, and light 116.

#FIG. 2 illustrates a simplified block diagram 120 of the brushless power tool 100, which includes a power source 122 (e.g., a battery pack), Field Effect Transistors (FETs) 124, a motor 126, hall sensors 128, a motor control unit 130, user input 132, and other components 133 (battery pack fuel gauge, work lights (LEDs), current/voltage sensors, etc.). The Hall sensors 128 provide motor information feedback, such as motor rotational position information, which can be used by the motor control unit 130 to determine motor position, velocity, and/or acceleration. The motor control unit 130 receives user controls from user input 132, such as by depressing the trigger 112 or shifting the forward/reverse selector 110. In response to the motor information feedback and user controls, the motor control unit 130 transmits control signals to accurately control the FETs 124 to drive the motor 126. By selectively enabling and disabling the FETs 124, power from the power source 122 is selectively applied to the motor 126 to cause rotation of a rotor. Although not shown, the motor control unit 130 and other components of the power tool 100 are electrically coupled to the power source 122 such that the power source 122 provides power thereto.

#FIG. 1 illustrates a brushless power tool.

#FIG. 2 illustrates a block diagram of a brushless power tool.

#FIGS. 3A, 3B, and 4 provide additional view of the brushless power tool of FIG. 1.

#Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

#FIG. 3A illustrates a cross section of the brushless power tool 100 of FIG. 1, and FIG. 3B illustrates select components of the power tool 100. The power tool 100 includes separate printed circuit boards (PCBs) for various components of the power tool 100. More particularly, the power tool 100 includes a control printed circuit board (PCB) 136, a power PCB 138, a forward/reverse PCB 140, a Hall sensor PCB 142, and a light-emitting diode (LED) PCB 144. Also illustrated in FIG. 3A is a drive mechanism 148 for transmitting the rotational output of the motor 126 to the output unit 107, and a cooling fan 149 rotated by the motor 126 and used to provide a cooling air flow over components of the power tool 100.

#As shown in FIG. 4, the control PCB 136 is positioned at the base of the tool 100 between the handle portion 104 and the battery interface 114, which may also be referred to as a terminal block portion. The control PCB 136 includes the motor control unit 130, which is operable to receive user input, to receive motor information feedback, and to control the FETs 124 to drive the motor 126. The control PCB 136 is electrically and physically coupled to terminal blades 150. When a battery pack (i.e., the power source 122) is coupled to the battery interface 114, terminals of the battery pack are received by and electrically coupled to the terminal blades 150. The number of terminal blades can vary based on the type of hand-held power tool. However, as an illustrative example, terminal blades 150 can include a battery positive (“B+”) terminal, a battery negative (“B−”) terminal, a sense or communication terminal, and an identification terminal. As shown in FIG. 4, the terminal blades 150 have tabs 152 that extend upward through the control PCB 136. The tabs 152 may be directly soldered to the control PCB 136, eliminating the need for additional power wires. The motor control unit may use the communication terminal to communicate with a battery pack, allowing the battery pack to communicate whether it is capable of discharging to the power tool 100 and other information.