US 12,459,154 B2
Cordless saw having improved cuts per battery charge
HuaMing Yao, Suzhou (CN); Yue Tian, Jiangsu (CN); Jun Liu, Suzhou (CN); Torrey R. Lambert, White Hall, MD (US); John S. Maceo, Jr., Annapolis, MD (US); Jason D. McKillican, Baltimore, MD (US); and YanJuan Zou, JiangSu (CN)
Assigned to BLACK & DECKER INC., New Britain, CT (US)
Filed by Black & Decker Inc., New Britain, CT (US)
Filed on Jul. 7, 2023, as Appl. No. 18/219,388.
Claims priority of provisional application 63/359,940, filed on Jul. 11, 2022.
Prior Publication US 2024/0009882 A1, Jan. 11, 2024
Int. Cl. H02P 3/14 (2006.01); B27B 5/38 (2006.01); B27B 9/00 (2006.01); H02J 7/14 (2006.01)
CPC B27B 5/38 (2013.01) [B27B 9/00 (2013.01); H02J 7/1415 (2013.01); H02P 3/14 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A cordless saw for repeated cutting of a workpiece, comprising:
a saw housing;
a battery connection port formed in the saw housing for receiving a removable battery pack;
an electric motor disposed within the housing and configured to rotatably drive an output shaft, wherein the output shaft is coupleable to a saw blade to perform a plurality of cutting operations on the workpiece;
a trigger switch operable by an operator for selective electronic connection or disconnection of a supply of electric power from the battery pack to the electric motor;
a power switch circuit disposed between the battery connection port and the electric motor; and
a control unit configured to regulate a switching operation of the power switch circuit for each of the plurality of cutting operations to supply electric power from the battery pack to the motor while the trigger switch is depressed and apply an regenerative braking period after the trigger switch is released, wherein during the regenerative braking period, the control unit applies a plurality of electronic braking periods to electric motor to slow down the rotation of the electric motor and a plurality of regenerative charging periods during which a regenerative energy induced by the electric motor charges the battery pack, wherein the regenerative energy is on average at least 33% of the average energy derived from the battery pack during the plurality of cutting operations,
wherein each of the plurality of cutting operations includes, prior to the regenerative braking period, a start-up period during which an electric current supplied to the motor ramps up to bring an output speed of the motor to a target speed, followed by a cutting period during which the saw blade engages the workpiece, wherein the regenerative braking period is longer than the start-up period.