Power tool, cutting tool, circular saw, and control method for power tool

Abstract

A power tool, a cutting tool, and a circular saw (100). The power tool comprises: a first motor (21; 21e; 21f) and a second motor (22; 22e; 22f), wherein a first driving shaft (211; 211e; 211f) and a second driving shaft (221; 221e; 221f) arranged along the radial direction of the first driving shaft (211; 211e; 211f) are provided; a power transmission mechanism (40) transmitting the power of at least one of the first motor (21; 21e; 21f) and the second motor (22; 22e; 22f) to an output shaft (30); and an accommodating housing (14), wherein when orthographic projection observation is performed in the extension direction of the output shaft (30), the ratio of an outer dimension Lc of the accommodating housing (14) along the direction of a line connecting a first axis (201) and a second axis (202) to an outer diameter dimension D of either of the motors is greater than or equal to 1.1. The power tool is driven by the two motors which cooperate with each other.

Description

Power tool, cutting tool, circular saw and power tool control method

[0001] This application claims the priority of Chinese patent application No. 202311129086.3 filed with the China Patent Office on September 1, 2023, the priority of Chinese patent application No. 202311809661.4 filed with the China Patent Office on December 25, 2023, the priority of Chinese patent application No. 202311803786.6 filed with the China Patent Office on December 25, 2023, the priority of Chinese patent application No. 202422000835.9 filed with the China Patent Office on August 16, 2024, and the priority of Chinese patent application No. 202421987 filed with the China Patent Office on August 16, 2024. The invention claims priority of the Chinese patent application No. 202411126105.1 filed with the Chinese Patent Office on August 16, 2024, priority of the Chinese patent application No. 202411132432.8 filed with the Chinese Patent Office on August 16, 2024, priority of the Chinese patent application No. 202422000293.5 filed with the Chinese Patent Office on August 16, 2024, and priority of the Chinese patent application No. 202411126175.7 filed with the Chinese Patent Office on August 16, 2024. The entire contents of the above applications are incorporated by reference into this application. Technical Field

[0002] The present application relates to an electric tool, for example, an electric tool, a cutting tool and a circular saw. Background Art

[0003] When operating a power tool in the related art, the output mechanism typically needs to be able to operate under both light and heavy load conditions. To enable the power tool to output high torque to accommodate heavy loads, a motor with high power and output torque is typically installed in the power tool. This high-power motor can drive the output mechanism to carry a large load. However, when the power tool is operating under light load, the high-power motor consumes a lot of power, resulting in significant waste. This reduces the motor's operating performance under light load conditions, reducing the power tool's usable life.

[0004] This section provides background information related to the present application which is not necessarily prior art.

[0005] Summary of the Invention

[0006] One object of the present application is to solve or at least alleviate some or all of the above problems. To this end, one object of the present application is to provide a power tool, a cutting tool and a circular saw that use two motors to cooperate to drive an output shaft to output work.

[0007] In order to achieve the above objectives, this application adopts the following technical solutions:

[0008] A power tool comprises: an output shaft configured to output torque; the output shaft rotates about the output axis; a first motor including a first drive shaft rotating about the first axis; a second motor including a second drive shaft rotating about the second axis; the first drive shaft and the second drive shaft are arranged radially along the first drive shaft; a power transmission mechanism transmitting power from at least one of the first motor and the second motor to the output shaft; the torque of the first drive shaft and the second drive shaft is output through the output shaft;

[0009] A containing shell is configured to accommodate a first motor and a second motor; when observed in orthographic projection along the extension direction of the output shaft, an outer dimension Lc of the containing shell along the direction of the line connecting the first axis and the second axis is greater than an outer diameter dimension D of any one of the motors; a main body shell includes a first marking structure corresponding to the first motor and a second marking structure corresponding to the second motor, the first marking structure is configured to indicate that the power tool is provided with a first motor, and the second marking structure is configured to indicate that the power tool is provided with a second motor.

[0010] In some embodiments, the first drive shaft is arranged in parallel with the second drive shaft.

[0011] In some embodiments, the first motor and the second motor at least partially overlap in the direction of the output axis.

[0012] In some embodiments, the first receiving portion at least supports a first bearing portion of the first motor away from the output shaft, and the second receiving portion at least supports a second bearing portion of the second motor away from the output shaft.

[0013] In some embodiments, it also includes: a first shell, a receiving shell formed or connected to the first shell, and the first shell is formed or connected with a gripping portion for grasping; a shield assembly, configured to accommodate at least part of the cutting piece driven by the output shaft; the shield assembly and the receiving shell are basically located on both sides of the first shell.

[0014] In some embodiments, the power transmission mechanism is housed in the first housing and is located outside the housing.

[0015] In some embodiments, a DC power supply is further included, which supplies power to the first motor and the second motor; the nominal voltage of the DC power supply is greater than or equal to 18V.

[0016] In some embodiments, the DC power source includes at least one battery pack.

[0017] In some embodiments, the first motor includes a first stator, a first rotor, and a coil winding disposed on the first stator, and the first drive shaft is formed or connected to the first rotor; the second motor includes a second stator, a second rotor, and a coil winding disposed on the second stator; the second drive shaft is formed or connected to the second rotor.

[0018] In some embodiments, the first motor and the second motor are configured to have at least one different first parameter, and the first parameter includes: maximum output speed, maximum output torque, stator core outer diameter, stator core inner diameter, rotor core outer diameter, rotor core inner diameter, rotor pole thickness, stator pole thickness, air gap length, core length, stator pole pair number, stator pole corresponding radian, rotor pole pair number and rotor pole corresponding radian.

[0019] In some embodiments, the first marking structure and the second marking structure are formed on or connected to an outer wall surface of the host housing.

[0020] In some embodiments, the first marking structure and the second marking structure are configured as independent double-barrel structures.

[0021] In some embodiments, the first logo structure includes a first display portion, and the second logo structure includes a second display portion. The first display portion and the second display portion are respectively arranged at easily visible positions on the host housing.

[0022] In some embodiments, the first display portion includes a light emitting body, and the light emitting body at least indicates the on / off status of the first motor.

[0023] In some embodiments, the first display portion includes an icon representing the first motor, the second display portion includes an icon representing the second motor, and the first display portion and the second display portion are respectively provided with a backing adhesive layer.

[0024] An electric tool comprises: an output shaft configured to output torque; the output shaft rotates around an output axis; a first motor comprising a first drive shaft rotating around the first axis; a second motor comprising a second drive shaft rotating around the second axis; the first drive shaft and the second drive shaft are arranged radially along the first drive shaft; a power transmission mechanism transmitting power of at least one of the first motor and the second motor to the output shaft; the torque of the first drive shaft and the second drive shaft is output through the output shaft; a housing shell configured to accommodate the first motor and the second motor; when observed by orthographic projection along the extension direction of the output shaft, the ratio of the outer dimension Lc of the housing shell along the line connecting the first axis and the second axis to the outer diameter dimension D of any one of the motors is greater than or equal to 1.1.

[0025] An electric tool comprises: an output shaft configured to output torque; the output shaft rotates around an output axis; a first motor comprising a first drive shaft rotating around the first axis; a second motor comprising a second drive shaft rotating around the second axis; the first drive shaft and the second drive shaft are arranged radially along the first drive shaft; a power transmission mechanism transmitting power of at least one of the first motor and the second motor to the output shaft; the torque of the first drive shaft and the second drive shaft is output through the output shaft; a housing configured to accommodate the first motor and the second motor; a main body housing comprising a first marking structure corresponding to the first motor and a second marking structure corresponding to the second motor, the first marking structure and the second marking structure being formed or connected on the outer wall surface of the main body housing; the first marking structure being configured to indicate that the electric tool is provided with the first motor, and the second marking structure being configured to indicate that the electric tool is provided with the second motor.

[0026] In some embodiments, the first marking structure and the second marking structure are arranged on the outer wall of a housing configured to accommodate the first motor and the second motor, and the first marking structure is configured to include a shape that is approximately the same as the outline of the first motor part; the second marking structure is configured to include a shape that is approximately the same as the outline of the second motor part.

[0027] In some embodiments, the first indicator structure includes a display screen that indicates an operating status of the first motor.

[0028] In some embodiments, the second display unit includes at least one of a light emitting body or a display screen, configured to indicate the operating status of the second motor.

[0029] An electric tool comprises: an output shaft configured to output torque; the output shaft rotates around an output axis; a first motor comprising a first drive shaft rotating around a first axis; a second motor comprising a second drive shaft rotating around a second axis; a power transmission mechanism transmitting power from at least one of the first motor and the second motor to the output shaft; the torque of the first drive shaft and the second drive shaft is output via the output shaft; the power transmission mechanism comprises: a transmission assembly configured between at least one of the first motor and the second motor and the output shaft; the transmission assembly comprises at least a reduction mechanism; a clutch assembly configured between the first motor and the second motor, the clutch assembly being configured to limit or allow at least one of the first drive shaft or the second drive shaft to drive the output shaft under preset conditions.

[0030] In some embodiments, the transmission assembly is configured to connect at least one of the first drive shaft and the second drive shaft to the clutch assembly.

[0031] In some embodiments, the transmission assembly includes a first gear assembly, wherein the first gear assembly connects the first motor and the output shaft, and the first gear assembly provides at least one reduction ratio.

[0032] In some embodiments, the transmission assembly includes a second gear assembly, the second gear assembly connects the second motor and the output shaft, and the second gear assembly provides at least one reduction ratio.

[0033] In some embodiments, the clutch assembly includes a one-way transmission operable to connect the first motor and the second motor in a first rotational direction and to decouple the first motor from the second motor in a second rotational direction.

[0034] In some embodiments, a clutch assembly connects the second gear assembly to the output shaft.

[0035] In some embodiments, the clutch assembly includes a third gear, the first gear set includes a first driven gear, the third gear is meshed with the first driven gear, and a transmission ratio of the third gear to the first driven gear is substantially 1.

[0036] In some embodiments, the clutch assembly rotates an idler shaft around a clutch axis, and the second gear set includes a second driven gear disposed on the idler shaft. When the rotation speed of the idler shaft is greater than the rotation speed of the output shaft, the clutch assembly drives the output shaft to rotate at the rotation speed of the idler shaft.

[0037] In some embodiments, a non-thrust bearing is provided at the first end of the idler shaft, and an elastic member is provided at one end of the non-thrust bearing.

[0038] In some embodiments, at least one of the first gear assembly and the second gear assembly includes a helical gear.

[0039] An electric tool comprises: an output shaft configured to output torque; the output shaft rotates around the output axis; a first motor comprising a first drive shaft rotating around the first axis; a second motor comprising a second drive shaft rotating around the second axis; a power transmission mechanism transmitting power of at least one of the first motor and the second motor to the output shaft; the torque of the first drive shaft and the second drive shaft is output through the output shaft; the power transmission mechanism comprises: a transmission assembly arranged between at least one of the first motor and the second motor and the output shaft; the transmission assembly comprises at least a reduction mechanism; in the direction along the output axis, the projection of the first axis and the projection of the second axis are located above the projection of the output axis.

[0040] In some embodiments, in the projection along the extension direction of the output axis, an angle α between a line connecting the first axis and the output axis and a line connecting the second axis and the output axis is greater than or equal to 45° and less than or equal to 180°.

[0041] A cutting tool comprises: an output shaft, configured to install a cutting piece; the cutting piece rotates around the output axis; a motor assembly, comprising: a first motor, comprising a first drive shaft rotating around a first axis; a second motor, comprising a second drive shaft rotating around a second axis; a first fan, supported by at least one of the first drive shaft, the second drive shaft and the output shaft; a power transmission mechanism, transmitting power of at least one motor in the motor assembly to the output shaft; a main housing, accommodating the motor assembly and the power transmission mechanism; an air flow port is formed on the main housing; a control circuit board, comprising a controller configured to control the motor assembly; the control circuit board is arranged in the main housing; when the first fan rotates, a heat dissipation air path can be generated, and the heat dissipation air path flows through at least the control circuit board and the motor assembly.

[0042] In some embodiments, the first fan is supported by the first drive shaft and driven by the first motor to rotate to generate a heat dissipation airflow; and further includes: a second fan, supported by the second drive shaft and driven by the second motor to rotate to generate a heat dissipation airflow, and the second fan can generate a heat dissipation air path when rotating, and the heat dissipation air path flows through at least the control circuit board and the motor assembly.

[0043] In some embodiments, the air flow port includes a first air inlet and a first air outlet, and the heat dissipation airflow enters the host housing from the first air inlet and flows out of the host housing from the first air outlet.

[0044] In some embodiments, the air flow outlet further includes a second air outlet, and the heat dissipation airflow flows out of the host housing from at least one of the first air outlet and the second air outlet, and the air outlet directions of the first air outlet and the second air outlet are different.

[0045] In some embodiments, the host shell includes a first shell and a receiving shell, wherein the first shell forms or is connected to the receiving shell, the receiving shell is configured to receive the first motor and the second motor, the control circuit board is arranged in the first shell, and the first air inlet allows the heat dissipation airflow from the first shell to enter the receiving shell.

[0046] In some embodiments, the first air outlet communicates with the receiving shell and the first shell.

[0047] In some embodiments, the cutting tool further includes: a base plate movably connected to the main body shell, the base plate forming a bottom surface in contact with the workpiece; a second air outlet is arranged on the base plate, and discharges air toward the side of the base plate.

[0048] In some embodiments, the heat dissipation air path includes a first heat dissipation air path and a second heat dissipation air path. The first heat dissipation air path is configured so that when at least one of the first motor or the second motor is running, the heat dissipation air flow enters from the first air inlet, flows through the control circuit board and the motor assembly, and then most of it flows out from the first air outlet; the second heat dissipation air path is configured so that when at least one of the first motor or the second motor is running, the heat dissipation air flow enters from the first air inlet, flows through the control circuit board and the motor assembly, and then most of it flows out from the second air outlet.

[0049] In some embodiments, a circuit board housing is further included for accommodating a control circuit board. The circuit board housing includes a heat dissipation plate connected to the control circuit board and capable of transferring heat generated by the control circuit board. The circuit board housing is arranged radially outside the motor assembly.

[0050] In some embodiments, it further includes: a fixed shield, which is configured to at least partially surround the cutting piece; the extension direction of the control circuit board is parallel to the extension direction of the cutting piece, and the control circuit board and the fixed shield are heat-conducted.

[0051] In some embodiments, at least one control circuit board is provided, and the circuit board housing can accommodate at least one control circuit board.

[0052] In some embodiments, it also includes: a power supply, including at least one battery pack configured to provide an energy source for the motor assembly; the battery pack is arranged between the motor assembly and the gripping portion for grasping, and a semi-open battery storage compartment formed by an inward recess is provided on the main body shell.

[0053] In some embodiments, when any one of the first fan and the second fan rotates, a heat dissipation air path can be generated, and the heat dissipation air path flows through at least the battery pack, the control circuit board and the motor assembly.

[0054] In some embodiments, the air flow port includes a second air inlet and a first air outlet. The heat dissipation airflow enters the battery compartment and the main body shell from the second air inlet and then flows out of the main body shell from the first air outlet.

[0055] In some embodiments, a circuit board housing is further included for accommodating a control circuit board. The circuit board housing includes a heat sink connected to the control circuit board and capable of transferring heat generated by the control circuit board. The circuit board housing is disposed between the motor assembly and the battery compartment.

[0056] A circular saw comprises: an output shaft, configured to mount a cutting piece; the cutting piece rotates about the output axis; a first motor, comprising a first drive shaft rotating about a first axis; a second motor, comprising a second drive shaft rotating about a second axis; a power transmission mechanism, transmitting power of at least one of the first motor and the second motor to the output shaft; a power supply, comprising at least one battery pack configured to provide an energy source for the motor; a main body housing, at least partially accommodating the first motor, the second motor and the power transmission mechanism; the main body housing comprises a first housing, the first housing forming or being connected with a gripping portion for grasping; a base plate, movably connected to the main body housing, the base plate forming a base bottom surface in contact with a workpiece; along an extension direction perpendicular to the cutting piece, a projection of the center of gravity of the circular saw is located between the rear edge of the base plate and the output axis.

[0057] In some embodiments, a projection of the center of gravity of the circular saw is close to the output axis and located behind the output axis.

[0058] In some embodiments, the cutting member extends in a cutting plane; the grip portion is substantially symmetrically arranged about the first plane; and the projection of the center of gravity of the circular saw in a direction perpendicular to the base plate is located between the cutting plane and the first plane or on the first plane.

[0059] In some embodiments, a distance from the center of gravity of the circular saw projected onto the first plane is smaller than a distance from the center of gravity of the circular saw to the cutting plane.

[0060] In some embodiments, a ratio of a distance W1 between the projection of the center of gravity of the circular saw and the first plane and a distance W2 between the cutting plane and the first plane is less than or equal to 1 / 3.

[0061] In some embodiments, the first motor, the second motor, the battery pack and the grip are arranged on the same side of the cutting member, and the battery pack is at least partially arranged behind the first motor and the second motor, and at least partially arranged in front of the grip.

[0062] In some embodiments, the first shell is formed with or connected to a receiving shell, and the receiving shell is configured to receive the first motor and the second motor.

[0063] In some embodiments, the bottom plate is formed with a hole extending along the first direction to allow the cutting piece to pass through the bottom plate. Along the first direction, the ratio of the outer edge dimension L3 of the receiving shell to the outer edge dimension La of the main shell is greater than or equal to 0.2 and less than or equal to 0.4.

[0064] In some embodiments, along the output axis direction, the ratio of the outer edge dimension H1 of the receiving shell to the outer edge dimension Ha of the main body shell is greater than or equal to 0.15 and less than or equal to 0.4.

[0065] In some embodiments, the cutting element has an outer diameter greater than 6 inches.

[0066] A circular saw comprises: an output shaft, configured to mount a cutting piece; the cutting piece rotates about the output axis; a first motor, comprising a first drive shaft rotating about the first axis; a second motor, comprising a second drive shaft rotating about the second axis; a power transmission mechanism, transmitting power of at least one of the first motor and the second motor to the output shaft; a power supply, comprising at least one battery pack configured to provide an energy source for the motor; a main housing, at least partially accommodating the first motor, the second motor and the power transmission mechanism; a base plate, movably connected to the main housing, the base plate forming a base plate bottom surface in contact with the workpiece; in a direction perpendicular to the bottom surface of the base plate, a projection of the first drive shaft and a projection of the second drive shaft have two endpoints that are farthest apart in the direction of the output axis, a width interval W is defined between two straight lines on the projection plane that pass through one endpoint respectively and are perpendicular to the output axis, and the projection of the center of gravity of the circular saw is set within the width interval W.

[0067] A circular saw comprises: an output shaft configured to mount a cutting piece; the cutting piece rotates about the output axis; a first motor comprising a first drive shaft rotating about a first axis; a second motor comprising a second drive shaft rotating about a second axis; the second drive shaft is coaxially arranged with the first drive shaft; the first motor and the second motor are mechanically coupled; a power transmission mechanism transmitting power from at least one of the first motor and the second motor to the output shaft; a power supply comprising at least one battery pack configured to provide an energy source for the motor; a motor diameter of the first motor is less than or equal to 70 mm, and a motor diameter of the second motor is less than or equal to 70 mm.

[0068] In some embodiments, the first motor is an outer rotor motor, and the second motor is an outer rotor motor.

[0069] In some embodiments, the first drive shaft rotates synchronously with the second drive shaft.

[0070] In some embodiments, the first motor includes a first stator and a first rotor, and the first drive shaft is formed or connected to the first rotor; the second motor includes a second stator and a second rotor; and the second drive shaft is formed or connected to the second rotor.

[0071] In some embodiments, a motor fixing portion is further included, and the motor fixing portion is connected to the first stator and the second stator respectively.

[0072] In some embodiments, the motor fixing portion is provided with a receiving channel, and the receiving channel is configured to receive at least a portion of the first drive shaft and the second drive shaft.

[0073] In some embodiments, the receiving channel at least partially overlaps with the first stator along the first axis direction, and the receiving channel at least partially overlaps with the second stator along the first axis direction.

[0074] In some embodiments, along the direction of the output axis, the projection of the first axis and the projection of the second axis are located above the projection of the output axis.

[0075] In some embodiments, the power transmission mechanism includes a transmission assembly, and the transmission assembly includes at least a reduction mechanism.

[0076] In some embodiments, it also includes: a base plate, the base plate is formed with a bottom surface of the base plate that contacts the workpiece; in the direction perpendicular to the bottom surface of the base plate, the projection of the first drive axis and the projection of the second drive axis have two endpoints that are farthest apart along the output axis direction, and a width interval W is defined between two straight lines on the projection plane that pass through one endpoint respectively and are perpendicular to the output axis, and the projection of the center of gravity of the circular saw is set within the width interval W.

[0077] An electric tool comprises: a functional part; a motor assembly, comprising a first motor and a second motor, at least one of the first motor and the second motor driving the functional part to operate; a power supply device connected to the motor assembly, for supplying power to the motor assembly at least; a transmission relationship between the first motor and the second motor, wherein the first motor drives the second motor to rotate when the first motor rotates; the electric tool further comprises: a controller connected to the motor assembly, the controller being configured to control the start-up of the second motor based on the back electromotive force of the second motor after the first motor is started.

[0078] In some embodiments, the second motor is a sensorless brushless motor.

[0079] In some embodiments, the controller is configured to control the first motor to start when receiving a signal to start the power tool.

[0080] In some embodiments, the controller is configured to control the start-up of the second motor based on the back electromotive force of the second motor after the first motor is started and a first preset time period has passed.

[0081] In some embodiments, the first preset time length is greater than or equal to 0.1 s and less than or equal to 2 s.

[0082] In some embodiments, the controller is configured to control the start-up of the second motor based on the back electromotive force of the second motor after the first motor is started and the speed of the first motor reaches a first speed threshold.

[0083] In some embodiments, the first speed threshold is greater than or equal to 10 RPM or greater than or equal to 10% of the no-load speed of the first motor.

[0084] In some embodiments, the controller is configured to determine the rotor position of the second motor based on an extreme value of the back electromotive force of the second motor or based on a relative relationship between the back electromotive force of the second motor and a zero potential, and control the start-up of the second motor.

[0085] In some embodiments, the controller includes a first controller and a second controller, the first controller is connected to the first motor, and the second controller is connected to the second motor; the first controller is configured to control the start of the first motor when receiving a signal to start the power tool; the second controller is configured to control the start of the second motor based on the back electromotive force of the second motor after the first motor is started.

[0086] A method for controlling an electric tool, comprising:

[0087] starting a first motor of the power tool;

[0088] The controller of the power tool controls the start of the second motor based on the back electromotive force of the second motor of the power tool after the first motor is started;

[0089] There is a transmission relationship between the first motor and the second motor, and when the first motor rotates, the second motor is driven to rotate.

[0090] An electric tool comprises: a functional part; a motor assembly, comprising a first motor and a second motor, at least one of the first motor and the second motor driving the functional part to operate; a power supply device, connected to the motor assembly, for at least supplying power to the motor assembly; the first motor and the second motor drive the same output shaft; the electric tool further comprises: a controller, connected to the motor assembly, the controller being configured to control the first motor to stop when a first motor parameter of the first motor exceeds a first protection threshold, and to control the second motor to stop when a second motor parameter of the second motor exceeds a second protection threshold after the first motor parameter exceeds the first protection threshold; the first protection threshold and the second protection threshold are not equal.

[0091] In some embodiments, the first motor parameter includes a first stall parameter of the first motor, and the first protection threshold includes a first stall threshold; the second motor parameter includes a second stall parameter of the second motor, and the second protection threshold includes a second stall threshold.

[0092] In some embodiments, the first motor parameter includes a first overcurrent parameter of the first motor, and the first protection threshold includes a first overcurrent threshold; the second motor parameter includes a second overcurrent parameter of the second motor, and the second protection threshold includes a second overcurrent threshold.

[0093] In some embodiments, the first stall parameter is the first commutation duration of the first motor, and the first stall threshold is the first duration threshold; the second stall parameter is the second commutation duration of the second motor, and the second stall threshold is the second duration threshold; the controller is configured to control the first motor to stop when the first commutation duration exceeds the first duration threshold, and control the second motor to stop when the second commutation duration exceeds the second duration threshold after the first commutation duration exceeds the first duration threshold; the first duration threshold is not equal to the second duration threshold.

[0094] In some embodiments, when the speed ratio of the first motor to the second motor is n:1, the ratio of the first duration threshold to the second duration threshold is not equal to 1:n.

[0095] In some embodiments, the first overcurrent parameter is the first current of the first motor, and the first overcurrent threshold is the first current threshold; the second overcurrent parameter is the second current of the second motor, and the second overcurrent threshold is the second current threshold; the controller is configured to control the first motor to stop when the first current exceeds the first current threshold, and to control the second motor to stop when the second current exceeds the second current threshold after the first current exceeds the first current threshold; the first current threshold is not equal to the second current threshold.

[0096] In some embodiments, when the torque ratio of the first motor to the second motor is n:1, the ratio of the first current threshold to the second current threshold is not equal to n:1.

[0097] In some embodiments, the first overcurrent parameter is the calculated value of one or more of the first output torque, first current, and first demagnetization time of the first motor; the second overcurrent parameter is the calculated value of one or more of the second output torque, second current, and second demagnetization time of the second motor.

[0098] In some embodiments, when the ratio of the first motor parameter to the second motor parameter is n:1, the ratio of the first protection threshold to the second protection threshold is not equal to n:1.

[0099] In some embodiments, the power tool further includes: a driving device, including a first driving circuit and a second driving circuit, the first driving circuit is connected between the power supply device and the first motor, and the second driving circuit is connected between the power supply device and the second motor.

[0100] In some embodiments, the first protection threshold has different values ​​when the capacity or voltage of the power supply device is different; and / or the second protection threshold has different values ​​when the capacity or voltage of the power supply device is different.

[0101] In some embodiments, the first protection threshold and / or the second protection threshold are dynamic thresholds, and the values ​​thereof correspond to the current or voltage of the motor component.

[0102] In some embodiments, the controller includes a first controller and a second controller, the first controller is connected to the first motor through a first drive circuit, and the second controller is connected to the second motor through a second drive circuit; the first controller is configured to control the first motor to stop when the first motor parameter of the first motor exceeds the first protection threshold; the second controller is configured to control the second motor to stop when the second motor parameter of the second motor exceeds the second protection threshold after the first motor parameter exceeds the first protection threshold; the first protection threshold and the second protection threshold are not equal.

[0103] An electric tool comprises: a functional part; a motor assembly, comprising a first motor and a second motor, at least one of the first motor and the second motor driving the functional part to operate; a power supply device, connected to the motor assembly, for at least supplying power to the motor assembly; wherein the first motor and the second motor drive the same output shaft; the electric tool further comprises: a controller, connected to the motor assembly, the controller being configured to control the first motor to stop when a first motor parameter of the first motor exceeds a first protection threshold, and to control the second motor to stop after the first motor parameter exceeds the first protection threshold and a second preset time has passed.

[0104] A method for controlling an electric tool comprises: a controller of the electric tool controlling the first motor to stop when a first motor parameter of the electric tool exceeds a first protection threshold; and controlling the second motor to stop when a second motor parameter of the second motor of the electric tool exceeds a second protection threshold after the first motor parameter exceeds the first protection threshold; the first protection threshold and the second protection threshold are unequal, and the first motor and the second motor drive the same output shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0105] FIG1 is a perspective structural diagram of a circular saw according to an embodiment of the present application;

[0106] FIG2 is a structural diagram of a circular saw according to an embodiment of the present application in a first state;

[0107] FIG3 is a structural diagram of a circular saw according to an embodiment of the present application in a second state;

[0108] FIG4 is a structural diagram of a circular saw according to an embodiment of the present application from another perspective, showing relevant components of a motor assembly;

[0109] FIG5 is a partial structural diagram of a circular saw according to an embodiment of the present application from a third perspective, with components related to the cutting element removed;

[0110] FIG6 is a partial view of the AA cross-sectional view in FIG5;

[0111] FIG7 is an exploded view of some components of a circular saw according to an embodiment of the present application;

[0112] FIG8 is a half-sectional view of a motor assembly and a receiving housing of a circular saw according to an embodiment of the present application;

[0113] FIG9 is a perspective structural diagram of another example of a circular saw according to an embodiment of the present application;

[0114] FIG10 is a perspective structural diagram of a third example of a circular saw according to an embodiment of the present application;

[0115] FIG11 is a cross-sectional view of the first motor in the motor assembly of the present application;

[0116] FIG12 is a schematic diagram of the structure of a power transmission mechanism of a circular saw according to an embodiment of the present application;

[0117] FIG13 is a schematic structural diagram of FIG12 from another perspective;

[0118] FIG14 is a schematic diagram of a partial cross-sectional view from another perspective of FIG13;

[0119] FIG15 is a schematic structural diagram of FIG13 from another perspective;

[0120] FIG16 is a schematic diagram of the structure of a second power transmission mechanism of a circular saw according to an embodiment of the present application;

[0121] FIG17 is a schematic diagram of the structure of a third power transmission mechanism of a circular saw according to an embodiment of the present application;

[0122] FIG18 is a schematic diagram of the structure of a fourth motor assembly, a power transmission mechanism, and a receiving housing of a circular saw according to an embodiment of the present application;

[0123] FIG19 is a schematic structural diagram of the motor assembly and power transmission mechanism in FIG18 from another perspective;

[0124] FIG20 is a schematic diagram of the internal structure of a circular saw according to an embodiment of the present application;

[0125] FIG21 is a schematic diagram of a partial structure of a circular saw according to an embodiment of the present application;

[0126] FIG22 is a partial cross-sectional view of the structure in FIG21;

[0127] FIG23 is a schematic structural diagram of another example having a structure different from that in FIG20 ;

[0128] FIG24 is a schematic structural diagram of a third example having a different structure from that in FIG20 ;

[0129] FIG25 is a schematic structural diagram of a fourth example having a structure different from that in FIG20 ;

[0130] FIG26 is a schematic structural diagram of a fifth example having a structure different from that in FIG20 ;

[0131] FIG27 is a schematic diagram of an electrical structure diagram of an embodiment of the present application;

[0132] FIG28 is a schematic diagram of another electrical structure diagram of an embodiment of the present application;

[0133] FIG29 is a control flow chart of an embodiment of the present application;

[0134] FIG30 is another control flow chart of an embodiment of the present application;

[0135] FIG31 is a perspective view of a power tool according to another embodiment of the present application from one viewing angle;

[0136] FIG32 is a perspective view of the power tool shown in FIG31 from another perspective;

[0137] FIG33 is a perspective view of a motor assembly in the power tool shown in FIG31 in one embodiment;

[0138] FIG34 is a perspective view of a motor assembly in another embodiment of the power tool shown in FIG31;

[0139] FIG35 is a schematic diagram of the electric control principle of the power tool shown in FIG31;

[0140] FIG36 is another electrical control schematic diagram of the power tool shown in FIG31;

[0141] FIG37 is a control flow chart of an electric tool according to an embodiment of the present application;

[0142] FIG38 is a control flow chart of an electric tool as another embodiment of the present application. DETAILED DESCRIPTION

[0143] Before any embodiments of the present application are explained in detail, it is to be understood that the application 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 foregoing drawings.

[0144] In this application, the terms "comprises," "includes," "has," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0145] In this application, the term "and / or" describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this application generally indicates that the related objects are in an "and / or" relationship.

[0146] In this application, the terms "connect," "combine," "couple," and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without an intermediary, and an indirect connection refers to two parts or components being connected to at least one intermediary, with the two parts or components being connected via the intermediary. Furthermore, "connect" and "couple" are not limited to physical or mechanical connections or couplings and may include electrical connections or couplings.

[0147] In this application, it will be understood by those skilled in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerance caused by manufacturing, assembly, use, etc. associated with a specific value. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0148] In this application, it will be understood by those skilled in the art that the function performed by an assembly can be performed by one assembly, multiple assemblies, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one assembly, or a combination of multiple parts.

[0149] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to the other element "upper" or "lower", but also be indirectly connected to the other element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, below can include directly below, lower left, lower right, lower front and lower back, etc.

[0150] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. Where a unit "controller," "processor," "central processing unit," "CPU," or "MCU" is used to perform a particular function, unless otherwise specified, the function may be performed by a single unit or multiple units.

[0151] In this application, the terms "device", "module" or "unit" can be implemented in the form of hardware or software to achieve specific functions.

[0152] In this application, the terms "calculate", "judge", "control", "determine", "identify", etc. refer to the operations and processes of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0153] In order to clearly illustrate the technical solution of the present application, an upper side and a lower side are defined in the drawings of the specification.

[0154] FIG1 shows a power tool according to an embodiment of the present application. The power tool includes a motor assembly 20. In this embodiment, the power tool is a circular saw 100. In some embodiments, the power tool can also be other cutting tools, such as a table saw, a miter saw, a marble saw, a tile saw, a chain saw, and the like.

[0155] In some embodiments, the power tool may also be a gardening tool, such as a lawn mower, a hair dryer, or a walk-behind power tool such as a lawn mower or a cleaning machine. Alternatively, the power tool may be a decorating tool, such as a screwdriver / drill / wrench, an electric hammer, a nail gun, or a sander. Alternatively, the power tool may be a reciprocating saw or a jigsaw. Alternatively, the power tool may be another benchtop tool, such as a router. Alternatively, the power tool may be a grinding tool, such as an angle grinder or a sander. Alternatively, the power tool may be another power tool, such as a fan. Alternatively, the power tool may be a non-road-going walking device, such as a utility vehicle, a dune buggy, a utility terrain vehicle (UTV), a golf cart, an all-terrain vehicle (ATV), or an agricultural vehicle, such as a harvester or a sprayer. Of course, it is understood that the walking device may also be a cleaning machine. Alternatively, the power tool may be an intelligent walking power tool that uses a motor or motor assembly to drive movement and perform operating functions, such as an intelligent lawn mower.

[0156] It is understood that any power tool driven by a motor can employ the technical solution disclosed in this embodiment, and any power equipment employing the technical solution disclosed in this embodiment falls within the scope of protection of this application. For example, the power tool may also be a power head, which includes a motor. The power head is configured to adapt to certain output components to achieve the tool's functions.

[0157] As shown in FIG1 , a circular saw 100 is used as an example. The circular saw 100 is a handheld circular saw. Unless otherwise specified, directional terms such as front, back, left, right, up, and down are relative to the direction of normal use of the circular saw 100. For example, the forward direction of the circular saw 100 is defined as the forward direction, and the direction opposite to the forward direction of the circular saw 100 is defined as the rear direction.

[0158] The circular saw 100 includes a power supply 31. In this embodiment, the power supply 31 is a DC power supply. The DC power supply provides electrical energy to the circular saw 100. The DC power supply includes at least one battery pack 31 configured to provide an energy source for the motor assembly 20. The battery pack 31 cooperates with the corresponding power supply circuit to power the circular saw 100. Those skilled in the art should understand that the power supply is not limited to the scenario of using a DC power supply, and can also be powered by AC power, AC power, and corresponding rectification, filtering and voltage regulation circuits to achieve power supply to the corresponding components in the machine. In the subsequent description, the battery pack 31 will replace the power supply 31, but it cannot be used as a limitation to this application.

[0159] The battery pack 31 may be a lithium battery pack, a solid-state battery pack, or a soft-pack battery pack. In some embodiments, when the power supply includes multiple battery packs 31, the battery packs 31 may be of the same or different types. In some embodiments, the electrical parameters, structural parameters, and physical parameters of the multiple battery packs 31 may be the same or different.

[0160] As shown in Figures 1 to 8, the circular saw 100 further includes an output shaft 30, a main body housing 11, a motor assembly 20, a power transmission mechanism 40, and a base plate 50. The output shaft 30 is configured to receive a cutting member 61. The cutting member 61 rotates about the output axis 301. In this embodiment, the cutting member 61 is a circular saw blade. The motor assembly 20 is configured to drive the output shaft 30 to rotate. The power transmission mechanism 40 is configured to transmit the output power of the motor assembly 20 to the output shaft 30. The main body housing 11 is configured to accommodate components such as the motor assembly 20 and the power transmission mechanism 40. The output shaft 30 and the cutting member 61 are disposed outside the main body housing 11. The base plate 50 is movably connected to the main body housing 11 and has a bottom surface 51 formed thereon for contacting a workpiece. The base plate 50 has a saw blade through-hole 54 extending in a first direction K1, through which a saw blade can pass and protrude downward from the bottom surface 51.

[0161] The main body housing 11 includes a first housing 111, which forms or is connected to a grip portion 12 for grasping. The grip portion 12 is located at the rear end of the circular saw 100 and can be grasped by the user to operate the circular saw 100 for cutting. In some embodiments, the grip portion 12 is also provided with a control switch 81 and a safety switch 82. The control switch 81 is activated only when the safety switch 82 is pressed. In other words, two actions are required before the motor or motor assembly 20 can be activated. This avoids the dangers of a single operation. When the user grasps the grip portion 12, the user's hand can trigger the safety switch 82 and the control switch 81 to start or stop the circular saw 100. In one embodiment, the first housing 111 may also form a second grip portion 13. The second grip portion 13 is located at the front end of the circular saw 100 and serves as an auxiliary handle. In one embodiment, the second grip portion 13 may also be an external handle mounted on the main body housing 11, that is, the second grip portion 13 may be a separate auxiliary operating component mounted on the main body housing 11.

[0162] The circular saw 100 also includes a guard assembly 60. The guard assembly 60 can at least partially surround the cutting member 61 to protect the environment and the safety of the user. The guard assembly 60 includes a fixed guard 62 with an arc-shaped structure, and a movable guard 63 that rotates relative to the fixed guard 62. The fixed guard 62 is connected to the first shell 111. The movable guard 63 is sleeved in the fixed guard 62 and can rotate around the output axis 301 to be folded into the fixed guard 62. The output shaft 30 extends into the fixed guard 62, and the cutting member 61 and the output shaft 30 are detachably connected. In actual work, different types of cutting members 61 can be used according to the material of the object to be cut. The cutting member 61 is arranged in the fixed guard 62, and almost the upper half of its outer circumference is covered by the fixed guard 62. The movable guard 63 rotates in the fixed guard 62 to cover or reveal the lower half of the cutting member 61. An opening piece 64 of the movable guard 63 is provided between the movable guard 63 and the fixed guard 62 . When the circular saw 100 is used, the operator manually pushes the opening piece 64 to rotate the movable guard 63 to expose a portion of the saw teeth.

[0163] The base plate 50 is movably connected to the fixed shield 62. In this embodiment, a connecting seat 52 is provided on the front side of the base plate 50. The connecting seat 52 and the fixed shield 62 are connected by a pin 53, allowing the fixed shield 62 to rotate relative to the base plate 50. The axis on which the pin 53 is located is defined as the pivot axis 501. The pivot axis 501 is parallel to the output axis 301. When the fixed shield 62 rotates relative to the base plate 50 about the pivot axis 501, the relative position between the fixed shield 62 and the base plate 50 changes, resulting in different cutting depths for the circular saw 100. The fixed shield 62 rotates by applying force to the handle 12, causing the handle 12 to rotate relative to the base plate 50, thereby driving the fixed shield 62 to rotate relative to the base plate 50. It will be appreciated that in some embodiments, the pivot axis 501 and the output axis 301 may intersect or be perpendicular.

[0164] As shown in Figures 6 and 8, the motor assembly 20 includes a first motor 21 and a second motor 22. The first motor 21 includes a first drive shaft 211 that rotates about a first axis 201. The second motor 22 includes a second drive shaft 221 that rotates about a second axis 202. The first motor 21 and the second motor 22 each include a stator and a rotor. Taking the first motor 21 as an example, as shown in Figure 11, the stator 212 includes a stator core 2121 and a stator winding 2122. The rotor 214 includes a rotor core 2141 and permanent magnets 2142. A drive shaft is formed on or connected to the rotor 214 and is configured to output power. For an outer rotor motor, the rotor is sleeved on the outside of the stator. For an inner rotor motor, the stator is sleeved on the outside of the rotor. In this embodiment, the overall structure of the motor is generally the same as that of a typical brushless motor and will not be described in detail here.

[0165] As shown in Figures 6 and 8, the power transmission mechanism 40 is configured to transmit power from at least one of the first motor 21 and the second motor 22 to the output shaft 30. The torque of the first drive shaft 211 and the second drive shaft 221 is output via the output shaft 30. In this embodiment, the first motor 21 and the second motor 22 work together to output the torque of the motor assembly 30 via the output shaft 30, and the torque is output outwardly through the output shaft 30. Taking the electric circular saw of the present application as an example, the first motor 21 and the second motor 22 work together to drive the cutting member 61 through the output shaft 30 to perform a cutting motion. Unlike related art multi-motor driven power tools, such as outdoor walking equipment or wheeled equipment, which use multiple motors, such as dual motors, to drive different output shafts or output parts, for example, in related art, the first motor and the second motor each drive two or more drive wheels or drive shafts. However, in this embodiment, a motor assembly including multiple motors drives the same output shaft. In other words, the torque of the drive shafts of the multiple motors is output through a single output shaft. The torque transmission paths of the multiple motors end at the same endpoint, increasing the efficiency range of the power tool and enabling even a power tool with only a single output shaft to be efficiently driven by multiple motors. Compared to multiple motors driving different output parts or output shafts, the present application utilizes multiple motors driving a single output shaft, necessitating greater challenges in the transmission coordination, power distribution, and drive structure of the motor assembly 20 and the power transmission mechanism 40.

[0166] As shown in Figures 4 to 10, the first motor 21 and the second motor 22 are arranged radially, that is, the first drive shaft 211 and the second drive shaft 221 are arranged radially with respect to the first drive shaft 211. Alternatively, the first drive shaft 211 and the second drive shaft 221 are arranged radially with respect to the second drive shaft 221. In this embodiment, the first drive shaft 211 and the second drive shaft 221 are parallel but do not overlap. In this embodiment, both the first drive shaft 211 and the second drive shaft 221 are arranged parallel to the output shaft 30. In some alternative embodiments, the first drive shaft 211 and the second drive shaft 221 intersect or are arranged perpendicular to each other.

[0167] The main housing 11 includes a receiving shell 14 configured to accommodate the motor assembly 20. The receiving shell 14 is formed on or connected to the first housing 111. In this embodiment, the shield assembly 60 and the receiving shell 14 are basically located on both sides of the first housing 111. It can be understood that the shield assembly 60 is located on the left side of the first housing 111, and the receiving shell 14 is located on the right side of the first housing 111. In this embodiment, the first housing 111 and the receiving shell 14 are connected to each other. A through hole 1111 for the receiving shell 14 to pass through is provided on the right side wall of the first housing 111. Among them, the power transmission mechanism 40 is accommodated in the first housing 111 and is located outside the receiving shell 14. This makes the arrangement of the components in the main housing 11 more reasonable.

[0168] The housing 14 includes a first housing portion 141 for accommodating the first motor 21 and a second housing portion 142 for accommodating the second motor 22. As shown in Figures 5 and 8, when viewed in orthographic projection along the extension direction of the output shaft 301, the ratio of the outer dimension Lc of the projection of the housing 14 to the outer diameter D1 or D2 of either motor, as measured along the line connecting the projection of the first axis 201 and the projection of the second axis 202, is greater than or equal to 1.1. When the first motor 21 and the second motor 22 are used to coordinately control the output of the output shaft 30, if the first motor 21 and the second motor 22 are not coaxially arranged, to ensure that both the first motor 21 and the second motor 22 can be stably installed, the size of the housing 14 needs to be greater than 1.1 times the diameter of a single motor. This allows for the first motor 21 and the second motor 22 to be stably installed by properly arranging their relative positions. Furthermore, this allows users to easily distinguish between products controlled by a single motor and those controlled by both the first motor 21 and the second motor 22.

[0169] In this embodiment, taking the second motor 22 as an example, the second motor 22 is an inner rotor motor, and the "motor outer diameter" refers to the outer diameter of the motor's stator. The outer diameter of the second motor 21 is D2. Along the line connecting the projection of the first axis 201 and the projection of the second axis 202, the ratio of the outer dimension Lc of the projection of the housing 14 to the outer diameter D2 of the second motor 21 is greater than or equal to 1.2, 1.4, 1.6, or 1.8. In some embodiments, along the line connecting the projection of the first axis 201 and the projection of the second axis 202, the ratio of the outer dimension Lc of the projection of the housing 14 to the outer diameter D2 of the second motor 21 is greater than or equal to 2. In some embodiments, along the line connecting the projection of the first axis 201 and the projection of the second axis 202, the ratio of the outer dimension Lc of the projection of the housing 14 to the outer diameter D2 of the second motor 21 is greater than or equal to 2.1 or 2.2. In this embodiment, the outer diameters of the first motor 21 and the second motor 22 are the same. In terms of arrangement, the first motor 21 and the second motor 22 are radially spaced apart. In this embodiment, as shown in Figures 6 and 8 , the first motor 21 and the second motor 22 do not overlap in a direction perpendicular to the bottom surface 51 of the base plate. In some embodiments, the first motor 21 and the second motor 22 do not overlap in the direction in which the cutting member 61 extends. In other words, no straight line extending along the output axis 301 can pass through both the first motor 21 and the second motor 22.

[0170] In this embodiment, the first motor 21 and the second motor 22 at least partially overlap in the direction of the output axis 301. That is, there exists at least one third straight line perpendicular to the output axis 301 that passes through both the first motor 21 and the second motor 22. This makes the motor assembly 20 more compact in the direction of the output axis 301. In this embodiment, along the line connecting the projections of the first axis 201 and the second axis 202, the outer dimension Lc of the projection of the housing 14 is greater than the outer dimension H1 of the housing 14 in the direction of the output axis 301. In other words, the radial dimension of the housing 14 is greater than its axial dimension.

[0171] As shown in Figures 6 and 8, the first housing portion 141 supports at least the first bearing portion 215 of the first motor 21. The first bearing portion 215 is the bearing portion on the side away from the output shaft 30. The first bearing portion 215 includes a ball bearing. The ball bearing supports the end of the first drive shaft 211 away from the output shaft 30. A first bearing seat 1411 supporting the ball bearing is provided on the bottom surface of the first housing portion 141. The second housing portion 142 supports at least the second bearing portion 225 of the second motor 22. The second bearing portion 225 is the bearing portion on the side away from the output shaft 30. The second bearing portion 225 includes a ball bearing. The ball bearing supports the end of the second drive shaft 221 away from the output shaft 30. A second bearing seat 1421 supporting the ball bearing is provided on the bottom surface of the second housing portion 142. This ensures that the first motor 21 and the second motor 22 are stably mounted in the first housing portion 141 and the second housing portion 142, respectively.

[0172] In some alternative embodiments, the first motor 21 and the second motor 22 are arranged to partially overlap in the radial direction. In other words, there is at least one fourth straight line parallel to the output axis 301 that passes through both the first motor 21 and the second motor 22. This allows the motor assembly 20 to be more compact in the radial direction. In this case, the outer dimension Lc of the housing 14 along the line connecting the projections of the first axis 201 and the second axis 202 can be less than or equal to the outer dimension H1 of the housing 14 along the output axis 301.

[0173] As shown in Figures 7 to 10 , the housing 14 includes a first marking structure corresponding to the first motor 21 and a second marking structure corresponding to the second motor 22. The first and second marking structures are formed or connected to the outer wall of the housing 14. This allows users to easily identify which motors 21 and 22 are used to drive the product. This externalization of the product's internal features increases user engagement in product selection.

[0174] In some embodiments, as shown in FIG7 , the first marking structure 71a is configured to include a shape that is similar to a partial outline of the first motor 21. The second marking structure 72a is configured to include a shape that is similar to a partial outline of the second motor 22. For example, the first marking structure 71a is the first receiving portion 141 in the receiving shell 14, and the outer wall of the first receiving portion 141 is an arc edge that is similar to the outer shape of the first motor 21. The second marking structure 72a is the second receiving portion 142 in the receiving shell 14, and the outer wall of the second receiving portion 142 is an arc edge that is similar to the outer shape of the second motor 22. Or, for example, the first marking structure 71a is the first receiving portion 141 in the receiving shell 14, and the second marking structure 72a is the second receiving portion 142 in the receiving shell 14. There is an obvious depression, protrusion, distinguishing shape, or separation mark between the first receiving portion 141 and the second receiving portion 142, which distinguishes the receiving shell 14 into partitions associated with the number of motors. It is understandable that the outer wall of the first receiving portion 141 can be designed into other shapes from the perspective of industrial design, and the outer wall of the second receiving portion 142 can be designed into other shapes from the perspective of industrial design, but in the technical field and in the eyes of ordinary consumers, their shapes can be identified as motors and can be understood as shapes similar to the outline of the motor. For example, in addition to the circle with the same shape as the motor, there are ellipses, shapes formed by the combination of arcs and straight lines, shapes formed by the combination of multiple arcs, rectangles, polygons, triangles and other styling lines.

[0175] In this embodiment, the outer walls of the first marking structure 71a and the second marking structure 72a are configured as a continuous surface. As shown in FIG7 , the outer walls of the first receiving portion 141 and the second receiving portion 142 are continuous structures, that is, the receiving housing 14 is an integral structure.

[0176] In some alternative embodiments, the first and second marking structures are configured as independent double-tube structures. The housing 14 may be a single, integral structure, with the first and second marking structures being two closed structures disposed on the outer wall of the housing 14. Alternatively, the housing 14 may be divided into two independent outer walls, the first receiving portion 141 and the second receiving portion 142.

[0177] In some alternative embodiments, as shown in FIG7 , the first marking structure 71b and the second marking structure 72b are additional line structures provided on the outer walls of the first housing portion 141 and the second housing portion 142. For example, the first marking structure 71b is a line structure on the outer wall of the first housing portion 141 that is similar to the outline of a motor. The second marking structure 72b is a line structure on the outer wall of the second housing portion 142 that is similar to the outline of a motor. The line structure can be a protruding line, an embedded line, a concave line, or a hollow line. For example, the first marking structure 71b is a line structure on the outer wall of the first housing portion 141 that is associated with representing a motor or the number of motors. The second marking structure 72b is a line structure on the outer wall of the second housing portion 142 that is associated with representing a motor or the number of motors, such as "text," "letters," "numbers," and the like, where "representing a motor" is a line structure that can be identified as a motor in the technical field and in the eyes of ordinary consumers.

[0178] In some alternative embodiments, as shown in FIG9 and FIG10 , the first indicator structure includes first display portions 71c and 71d, and the second indicator structure includes second display portions 72c and 72d. The first display portions 71c and 71d, and the second indicator structure includes second display portions 72c and 72d, are respectively disposed at easily visible locations on the main housing 11. This allows the user to confirm the operating status of the first motor 21 and the second motor 22 by simply moving their line of sight while using the circular saw 100.

[0179] In some embodiments, as shown in Figure 9, the first display unit 71c includes a light-emitting diode (LED), a chip-on-board (COB) lamp, or an incandescent lamp. The first display unit 71c is disposed on the upper surface of the first housing 111, and is located on the upper surface portion of the first housing 111 near the housing 14. In some embodiments, the first display unit 71c is located on the upper surface of the housing 14. The first display unit 71c indicates the on / off status of the first motor 21 through changes in the display, such as by lighting up and off, continuously lighting and flashing, or using different colors. The first display unit 71c can also be multiple lights or a light strip. The different display characteristics of different numbers or segments of lights can be used to indicate the speed range of the first motor 21. In some embodiments, the first display unit 71c can also indicate abnormalities, serving as an abnormality alarm.

[0180] In some alternative embodiments, as shown in Figure 10, the first display unit 71d includes a display screen, which serves as a human-machine interaction interface to display the operating status of the first motor 21. For example, the first display unit 71d includes a light emitting diode (LED) display screen, a liquid crystal display (LCD) display screen, or an organic electroluminescence display (OLED) display screen. The first display unit 71d is arranged on the upper surface of the receiving shell 14. In some embodiments, the first display unit 71d is arranged on the upper surface of the first shell 111, and the first display unit 71d is arranged on the upper surface portion of the first shell 111 close to the receiving shell 14. Among them, since the display screen serves as a human-machine interaction interface, the displayed content is more detailed and more intuitive. Therefore, depending on the settings, the display screen can display various information about the first motor 21 during the working process, such as power on and off information, speed information, output torque information, forward and reverse rotation information, loss information, temperature information, and even intuitively display the first motor 21 in the form of dynamic shape on the display screen.

[0181] In some embodiments, the first display unit can include both a light source and a display screen. The second display unit 72c includes at least one of a light source and a display screen, and is configured to indicate the operating status of the second motor 22. That is, the first display units 71c, 71d and the second display unit 72c can be the same type of display component or different types of display components. To facilitate user observation, the first display units 71c, 71d and the second display unit 72c are positioned in the same area, for example, both positioned in the upper portion of the housing 14, with one positioned near the first motor 21 and the other near the second motor 22. When the first and second display units use the same type of display component, the first and second display units can be integrated, for example, using LED lights of varying brightness and colors to indicate different motor activation combinations. For example, different display areas of the same display interface can be used to display information about the first and second motors 21, 22, or different display interfaces can be used to display information about the first and second motors 21, 22, respectively. Alternatively, a menu can be used to allow the user to select which information to display: the first motor 21, the second motor 22, or both.

[0182] In some embodiments, the first display portion 71e includes an icon representing the first motor 21, and the second display portion 72e includes an icon representing the second motor 22. Each of the first display portion 71e and the second display portion 72e is provided with an adhesive layer. In other words, the first display portion 71e and the second display portion 72e function as adhesive labels. The icon representing the first motor 21 and the icon representing the second motor 22 can be in Chinese, English, or a graphic. The first display portion 71e and the second display portion 72e can be provided on the same adhesive-backed paper.

[0183] The technical solutions in the above embodiments may be used partially alone or in combination with several of the technical solutions, so as to set the specific implementation of the first marking structure and the second marking structure according to the actual needs of the electric tool.

[0184] As shown in Figures 6 and 12 to 16, the power transmission mechanism 40 is configured to transmit the power of at least one of the first motor 21 and the second motor 22 to the output shaft 30. The torque of the first drive shaft 211 and the second drive shaft 221 is output through the output shaft 30. The power transmission mechanism 40 includes: a transmission assembly 41 is arranged between at least one of the first motor 21 and the second motor 22 and the output shaft 30. The transmission assembly 41 includes at least a reduction mechanism. A clutch assembly 42 is arranged between the first motor 21 and the second motor 22. The clutch assembly 42 is configured to limit or allow at least one of the first drive shaft 211 or the second drive shaft 221 to drive the output shaft 30 under preset conditions. This allows the first motor 21 and the second motor 22 to drive the output shaft 30 to operate in a range where their respective motor efficiencies are relatively high. It will be appreciated that the clutch assembly 42 is disposed between the first motor 21 and the second motor 22. On the one hand, in terms of orientation, the clutch assembly 42 at least partially overlaps with either the first motor 21 or the second motor 22 in the axial direction of the drive shaft, or at least partially overlaps with either the first motor 21 or the second motor 22 in the radial direction of the drive shaft. On the other hand, in terms of connection, the clutch assembly 42 has a direct or indirect connection, or a direct or indirect power transmission path, with each of the first motor 21 and the second motor 22.

[0185] The provision of a transmission assembly 41 with a speed reduction and distance increase improves the cutting capacity and efficiency of the circular saw 100. The coupling of the motor assembly 20 allows the circular saw 100 to operate in both light and high load conditions. This also reduces the performance requirements of the motor in the motor assembly, enabling the use of a smaller diameter motor to achieve the performance requirements of a larger motor. This not only reduces costs but also reduces requirements for heat dissipation and other aspects of the machine.

[0186] The transmission assembly 41 is configured to connect at least one of the first drive shaft 211 and the second drive shaft 221 with the clutch assembly 42. As shown in Figures 19 to 21, in one embodiment, the transmission assembly 41 includes a first gear set 41a, which is configured to connect the first drive shaft 211 and the output shaft 30. The transmission assembly 41 also includes a second gear set 41b, which connects the second drive shaft 221 and the output shaft 30, with the clutch assembly 42 disposed between the second gear set 41b and the output shaft 30. In this embodiment, the first gear set 41a is a reduction gear transmission, and the second gear set 41b is a reduction gear transmission. The first gear set 41a is a single-stage reduction transmission, that is, the first gear set 41a provides a single reduction motion. The second gear set 41b is a single-stage reduction transmission, that is, the second gear set 41b provides a single reduction motion. In alternative embodiments, the first gear set 41a and the second gear set 41b may also include multiple reduction gear transmissions, or a speed-up transmission followed by a speed-down transmission. In some alternative embodiments, the transmission ratio or reduction ratio of the first gear set 41a and the second gear set 41b can be adjusted so that a single gear set can provide multiple transmission ratios or reduction ratios. In this embodiment, the reduction ratio of the first gear set 41a is different from the reduction ratio of the second gear set 41b. The first gear set 41a and the second gear set 41b each include one or a combination of cylindrical gear transmission, bevel gear transmission, worm gear transmission, and planetary gear transmission.

[0187] The first gear set 41a includes a first driving gear 411 and a first driven gear 412. The first driving gear 411 is formed on or connected to the first drive shaft 211. Optionally, the first driving gear 411 is formed on an end of the first drive shaft 211 near the cutting member 61. The first driving gear 411 rotates around the first axis 201, and the first driven gear 412 is externally meshed with the first driving gear 411. The first driven gear 412 is mounted on the output shaft 30 and rotates around the output axis 301. The first driving gear 411 and the first driven gear 412 form a reduction transmission. As an embodiment, the reduction ratio between the first driving gear 411 and the first driven gear 412 is 8 / 38.

[0188] The second gear set 41b includes a second driving gear 413 and a second driven gear 414. The second driving gear 413 is formed on or connected to the second drive shaft 221. Optionally, the second driving gear 413 is formed on the end of the second drive shaft 221 near the cutting element 61. The second driving gear 413 rotates about the second axis 202. The second driven gear 414 is externally meshed with the second driving gear 413 and mounted on an idler shaft 415. The second driven gear 414 rotates about the third axis 401 of the idler shaft 415. The third axis 401 is parallel to, but not coincident with, the first axis 201. The second driving gear 413 and the second driven gear 414 form a reduction gear. In this embodiment, the clutch assembly 42 includes a one-way transmission member 421. The one-way transmission member 421 is operable to connect the first motor 21 and the second motor 22 for rotation in a first rotational direction and to decouple the first motor 21 and the second motor 22 for rotation in a second rotational direction. Optionally, the clutch assembly 42 is a one-way bearing or overrunning clutch. A one-way transmission member 421 is mounted on the idler shaft 415 and rotates synchronously with the second driven gear 414. The inner ring of the one-way transmission member 421 is connected to the idler shaft 415, while the outer ring of the one-way transmission member 421 is connected to a third gear 422. The third gear 422 externally meshes with the first driven gear 412 to couple the first motor 21 with the second motor 22, thereby controlling the transmission between the second motor 22 and the first motor 21. In this embodiment, the third gear 422 and the first driven gear 412 are essentially isochronous, meaning the rotational speed of the third gear 422 is the same as that of the first driven gear 412. The transmission ratio between the third gear 422 and the first driven gear 412 is 1. In one embodiment, the reduction ratio between the second driving gear 413 and the second driven gear 414 is 7 / 38.

[0189] During operation, when the first motor 21 starts, it drives the output shaft 30 to rotate via the first gear set 41a. The one-way transmission member 421 restricts the transmission of the output speed of the first motor 21 to the second motor 22. Specifically, the one-way transmission member 421 only allows the second drive shaft 221 (second driving gear) of the second motor 22 to transmit rotation to the second driven gear 414. At this point, only the first motor 21 drives the output shaft 30. When the second motor 22 starts, the rotation lock of the one-way transmission member 421 is released. When the speed of the second driven gear 414 is less than that of the third gear 422, the speed of the second driven gear 414 cannot be transmitted to the output shaft. It will be understood that when the power output portion of the one-way clutch (the outer ring in this embodiment) rotates faster than the power source (the inner ring in this embodiment), the one-way clutch is disengaged, and there is no linkage between the inner and outer rings. This is the one-way overrunning function of the one-way clutch. When the speed of the second driven gear 414 is equal to or greater than the speed of the first driven gear 412, that is, when the speed of the second driven gear 414 is equal to or greater than the speed of the third gear 422, the inner and outer rings of the one-way clutch are in tandem, and the first motor 21 and the second motor 22 simultaneously drive the output shaft 30. Simultaneously, the first driven gear 412 is driven by the second driven gear 414 through the third gear 422, so that the first driven gear 412 moves at the speed of the second driven gear 414 (i.e., the idler shaft 415).

[0190] A non-thrust bearing 416 is provided at the first end of the idler shaft 415 , and an elastic member 417 is provided at one end of the non-thrust bearing 416 to prevent the gear on the idler shaft 415 from moving.

[0191] In some embodiments, the clutch assembly also includes other mechanical clutch assemblies. For example, dog clutches, ratchet clutches, centrifugal clutches, differentials, friction clutches, and hydraulic clutches. Simple variations or combinations of these mechanical clutches can all be used as the clutch assembly of this application. The specific form of the structure does not affect the substantive content of this application, provided it can fulfill the functions of the clutch assembly of this application.

[0192] In some embodiments, the clutch assembly further includes an electronic clutch, such as an electromagnetic clutch, such as a dry single-plate electromagnetic clutch, a dry multi-plate electromagnetic clutch, a wet multi-plate electromagnetic clutch, a magnetic powder clutch, or a slip electromagnetic clutch.

[0193] In some embodiments, the coupling of the mechanical clutch assembly and the electronic clutch can be used simultaneously to limit or allow at least one of the first drive shaft 211 or the second drive shaft 221 to drive the output shaft 30 under preset conditions.

[0194] As shown in Figure 15 , along the direction of the output axis 301, the projections of the first axis 201 and the second axis 202 are located above the projection of the output axis 301. This allows the motor assembly to be positioned more above the output shaft. This arrangement ensures the cutting depth of the circular saw. The output axis 301 is essentially the center of the cutting element 61, and the cutting depth of the circular saw is closely related to the position of the output axis relative to the base plate. Positioning the motor assembly's drive axis above the output axis does not affect the installation and operation of the circular saw's base plate. During the circular saw's cutting depth, there is no interference with components near the base plate associated with the output axis. The angle α between the line connecting the first axis 201 and the output axis 301 and the line connecting the second axis 202 and the output axis 301 is greater than or equal to 45° and less than or equal to 180°. This ensures a compact arrangement of the first and second motors within the transmission arrangement and the output shaft.

[0195] Optionally, the first motor 21 and the second motor 22, when radially arranged, are vertically staggered. The output shaft 30 and the idler shaft 415 are located on either side of the first drive shaft 211. The output shaft 30 and the idler shaft 415 are located on either side of the second drive shaft 221. In this embodiment, the first motor 21 is a low-torque output motor, and the second motor 22 is a high-torque output motor. At least one gear assembly in the first gear set 41a and the second gear set 41b includes a helical gear.

[0196] As shown in Figure 16, when the first motor 21e and the second motor 22e are arranged radially, the first drive shaft 211e and the second drive shaft 221e are substantially aligned in the vertical direction. The output shaft 30 and the idler shaft 415e are respectively located on the same side of the first drive shaft 211e.

[0197] As shown in Figure 17, as an embodiment, the first motor 21f and the second motor 22f are arranged radially, and the first driving gear 411f on the first drive shaft 211f and the second driving gear 413f on the second drive shaft 221f are both externally meshed with the driven gear 412f on the output shaft 30f. In this case, the first motor 21f and the second motor 22f may not be provided with a clutch assembly, that is, the output torque of the first motor and the second motor is synchronized or substantially synchronized. In this case, in the direction along the output axis 301, the projection of the first axis 201 and the projection of the second axis 202 are located above the projection of the output axis 301. The angle α between the line connecting the first axis and the output axis and the line connecting the second axis and the output axis is greater than or equal to 45° and less than or equal to 180°.

[0198] As shown in Figures 18 and 19, as another embodiment of the present application, the first motor 21g and the second motor 22g are arranged axially. That is, the first drive shaft 211g of the first motor 21g and the second drive shaft 221g of the second motor 22g are coaxially arranged. The first drive shaft 211g and the second drive shaft 221g are mechanically coupled. A first driving gear 411g on the first drive shaft 211g is externally meshed with a driven gear 412g on the output shaft 30g. The first driving gear 411g and the driven gear 412g form a reduction transmission.

[0199] The receiving shell 14g is configured to receive the first motor 21g and the second motor 22g. Optionally, the first receiving portion 141g for receiving the first motor 21g and the second receiving portion 142g for receiving the second motor 22g of the receiving shell 14g are arranged axially. The ratio of the outer dimension Lc' of the receiving shell 14g along the direction of the first drive shaft 211g or the second drive shaft 221g to the length of any one of the first drive shaft 211g and the second drive shaft 221g is greater than or equal to 1.1. When the first motor 21g and the second motor 22g are coaxially arranged, in order to ensure that the first motor 21g and the second motor 22g can be installed stably, the size of the receiving shell 14g needs to be greater than 1.1 times the length of a single drive shaft. In this way, the relative positions of the first motor 21g and the second motor 22g can be reasonably arranged so that the first motor 21g and the second motor 22g have space to be installed stably. In some embodiments, the ratio of the outer dimension Lc' of the housing 14g along the direction of the first drive shaft 211g or the second drive shaft 221g to the length of either the first drive shaft 211g or the second drive shaft 221g is greater than or equal to 1.2, 1.4, 1.6, or 1.8. In some embodiments, the ratio of the outer dimension Lc' of the housing 14g along the direction of the first drive shaft 211g or the second drive shaft 221g to the length of either the first drive shaft 211g or the second drive shaft 221g is greater than or equal to 2. In some embodiments, the ratio of the outer dimension Lc' of the housing 14g along the direction of the first drive shaft 211g or the second drive shaft 221g to the length of either the first drive shaft 211g or the second drive shaft 221g is greater than or equal to 2.1 or 2.2.

[0200] As shown in Figure 19, the first motor 21g is an outer rotor motor, and the second motor 22g is an outer rotor motor. The first motor 21g includes a first stator 212g and a first rotor 214g. A first drive shaft 211g is formed or connected to the first rotor 214g. The second motor 22g includes a second stator 222g and a second rotor 224g. A second drive shaft 221g is formed or connected to the second rotor 224g.

[0201] The first drive shaft 211g and the second drive shaft 221g rotate synchronously. In this embodiment, the first drive shaft 211g and the second drive shaft 221g are integrally formed. In some embodiments, the first drive shaft 211g and the second drive shaft 221g can be separate independent shafts, connected by a connector or fastener to achieve the effect of synchronous rotation. The motor fixing portion 24g is further provided with a motor fixing portion 24g configured to be connected to the first stator 212g and the second stator 222g respectively. The motor fixing portion 24g is provided with a receiving channel 241g, which is configured to accommodate at least a portion of the first drive shaft 211g and the second drive shaft 221g. The receiving channel 241g at least partially overlaps with the first stator 212g along the first axis 201, and the receiving channel 241g at least partially overlaps with the second stator 222g along the first axis 201. The stator 212 of the first motor and the stator 222 of the second motor are coaxially connected via the motor fixing portion 24g.

[0202] In some alternative embodiments, a clutch assembly is provided between the first motor shaft and the second motor shaft, or a clutch assembly is provided between the first motor and the output shaft, or a clutch assembly is provided between the second motor and the output shaft, so that the power of the first motor and the second motor can be selectively transmitted to the output shaft. The clutch assembly can be any of the clutch structures in the above embodiments. The clutch assembly is provided in the motor fixing portion, or between the first driving gear 411g and the first driven wheel. At this time, in the direction along the output axis 301, the projection of the first axis 201 and the projection of the second axis 202 are located above the projection of the output axis 301.

[0203] In the present application, the first motor 21 outputs a first torque and a first speed. The second motor 22 outputs a second torque and a second speed. In some embodiments, the first torque and the second torque are different. The first speed and the second speed are different. It should be noted that the difference between the first torque and the second torque, in some embodiments, means that the maximum output torques of the first motor 21 and the second motor 22 are different, but the first motor 21 and the second motor 22 have the same output torque at a certain moment or a certain period of time during their entire operation. In some embodiments, the difference between the first torque and the second torque, in some embodiments, means that the first motor 21 and the second motor 22 have different output torque ranges in the high-efficiency range, but the first motor 21 and the second motor 22 have the same output torque at a certain moment or a certain period of time during their entire operation. The difference between the first speed and the second speed, in some embodiments, means that the maximum output speeds of the first motor 21 and the second motor 22 are different, but the first motor 21 and the second motor 22 have the same output speed at a certain moment or a certain period of time during their entire operation. In some embodiments, the difference between the first speed and the second speed, in some embodiments, means that the maximum output speeds of the first motor 21 and the second motor 22 are different, but the first motor 21 and the second motor 22 have the same output speed at a certain moment or a certain period of time during their entire operation.

[0204] In some embodiments, the first motor 21 and the second motor 22 are configured as a low-output torque motor. As an example, the first motor 21 is a low-output torque motor, and the second motor 22 is a high-output torque motor. Alternatively, the first motor 21 may be a high-output torque motor, and the second motor 22 may be a low-output torque motor. Alternatively, the first motor 21 and the second motor 22 may be the same type of motor, but differ in output speed and output torque. In this embodiment, both the first motor 21 and the second motor 22 are brushless DC motors.

[0205] At the same time, the first motor 21 and the second motor 22 also have at least one different structural parameter. The structural parameters include the motor's outer diameter D and the motor stack length. It should be explained here that the "motor outer diameter" refers to the overall outer diameter of the motor. The "motor stack length" refers to the stator core length. In this embodiment, the motor diameter of the first motor 21 is less than or equal to 75 mm. The motor diameter of the first motor 21 is less than or equal to 70 mm. The motor diameter of the first motor 21 is less than or equal to 65 mm. In some embodiments, the motor diameter of the first motor 21 is less than or equal to 69 mm, 68 mm, 67 mm, 66 mm, 64 mm, 63 mm, 62 mm, 61 mm, 60 mm, 59 mm, 58 mm, 57 mm, 56 mm, or 55 mm. In this embodiment, the motor diameter of the second motor 22 is less than or equal to 75 mm. The motor diameter of the second motor 22 is less than or equal to 70 mm. The motor diameter of the second motor 22 is less than or equal to 65 mm. In some embodiments, the motor diameter of the second motor 22 is less than or equal to 69 mm, 68 mm, 67 mm, 66 mm, 64 mm, 63 mm, 62 mm, 61 mm, 60 mm, 59 mm, 58 mm, 57 mm, 56 mm, or 55 mm.

[0206] In some embodiments, the structural parameters of the first motor 21 and the second motor 22 include the stator core outer diameter, the stator core inner diameter, the rotor core outer diameter, the rotor core inner diameter, the rotor pole thickness, the stator pole thickness, the air gap length, the core length, the number of stator pole pairs, the corresponding arc angle of the stator poles, the number of rotor pole pairs, and the corresponding arc angle of the rotor poles. The first motor 21 and the second motor 22 may differ in at least one structural parameter.

[0207] Of course, in some embodiments, the first motor 21 and the second motor 22 can be two identical motors, and a higher efficiency range can be achieved through mutual coupling.

[0208] In this embodiment, the battery pack 31 supplies power to the first motor 21 and the second motor 22. The battery pack 31 cooperates with the corresponding power supply circuit to supply power to the first motor 21 and the second motor 22. As shown in Figures 5 and 7, the host housing 11 is provided with a semi-open battery storage compartment 15 formed by an inward depression. The battery storage compartment 15 is arranged between the grip portion 12 and the motor assembly 20. The battery storage compartment 15 and the motor assembly 20 are arranged on the same side of the first housing 111. The battery storage compartment 15 and the battery pack 31 are arranged in front of the grip portion 12. The battery storage compartment 15 is arranged on the first housing 111.

[0209] As shown in Figure 20, the battery compartment 15 includes a coupling portion 1511 electrically connected to the battery pack 31. Tool terminals (not shown) are provided on the coupling portion 1511. Tool terminals (not shown) with identical structures are provided on different power tools. The battery pack 31 includes an inserting structure and a terminal interface. The tool terminals adapt to the terminal interface on the battery pack 31. The provision of identical tool terminals on different power tools allows the battery pack 31 to power a variety of different power tools. The power supply circuitry used with these terminals is adjusted based on the control requirements of different power tools. In some embodiments, the nominal voltage of the power tool is greater than or equal to 18V. The nominal voltage of the power tool is greater than or equal to 36V and less than or equal to 56V. In some embodiments, the nominal voltage of the power tool is greater than or equal to 56V and less than or equal to 120V. The first motor 21, the second motor 22, the battery pack 31, and the grip 12 are disposed on the same side of the cutting element 61. After the battery pack 31 is inserted into the battery compartment 15, it is at least partially positioned after the first and second motors are positioned, and at least partially positioned before the grip 12. Optionally, the battery pack 31 is inserted into the battery compartment 15 at an angle. In some embodiments, the battery pack 31 is partially located above the first motor and the second motor.

[0210] As shown in FIG20 , the circular saw 100 further includes a controller 17 configured to control the motor assembly 20. The controller 17 is mounted on a control circuit board 18, which includes a printed circuit board (PCB) and a flexible printed circuit board (FPC). The controller 17 utilizes a dedicated control chip, such as a single-chip microcomputer (MCU) or a microcontroller unit (MCU). It should be noted that the control chip can be integrated into the controller 17 or provided independently of the controller 17. The structural relationship between the driver chip and the controller 17 is not limited in this embodiment.

[0211] As shown in Figures 6 and 8, the motor assembly 20 further includes a first fan 216 supported by the first drive shaft 211. The first fan 216 is driven by the first motor 21 to rotate and generate a cooling airflow. A second fan 226 is supported by the second drive shaft 221 and is driven by the second motor 22 to rotate and generate a cooling airflow. As shown in Figures 21 and 22, airflow openings are formed in the main body housing 11. When either the first fan 216 or the second fan 226 rotates, a cooling airflow path is generated. The cooling airflow path passes through at least the control circuit board 18 and the motor assembly 20. Brushless motors have higher output power than brushed motors. However, this also increases the heat dissipated by the brushless motor itself and the control circuit board 18, which controls the power supply to the motor. Therefore, sufficient heat dissipation from the control circuit board 18 is required. In some embodiments, when the first and second motors are coaxially arranged, only the first fan can be supported by at least one of the first drive shaft, the second drive shaft, or the output shaft. When any one of the first motor and the second motor rotates, the first fan rotates and creates a heat dissipation air path.

[0212] The airflow port includes a first air inlet 161 and a first air outlet 162. The heat dissipation airflow enters the main housing 11 through the first air inlet 161 and exits the main housing 11 through the first air outlet 162. The control circuit board 18 is disposed within the first housing 111. The first air inlet 161 allows the heat dissipation airflow from the first housing 111 to enter the receiving housing 14. When any motor in the motor assembly 20 is activated, the corresponding fan rotates synchronously to generate a heat dissipation airflow. This allows the heat dissipation airflow to flow through at least the control circuit board 18 and the motor assembly 20. In other words, at least one of the control circuit board 18 and the motor assembly 20 must be disposed within the heat dissipation airflow path. Thus, when any motor in the motor assembly 20 is activated and the fan rotates, external air can flow into the interior of the circular saw 100 through the air inlet, forming a heat dissipation airflow. Furthermore, as the heat dissipation airflow flows toward the fan, it passes through at least the circuit board and any one of the motors in the motor assembly 20 before finally flowing out through the air outlet.

[0213] Figures 20 to 22 illustrate a first embodiment of a heat dissipation solution. The control circuit board 18 is positioned above the motor assembly 20. The plane in which the control circuit board 18 extends is defined as a second plane S2. The plane in which the bottom surface 51 of the base plate 50 lies is defined as a third plane S3. In a direction perpendicular to the extension of the cutting member 61, i.e., along the output axis, the second plane S2 is a straight line, and the third plane S3 is a straight line. The second plane S2 and the third plane S3 can be parallel or intersecting. The control circuit board 18 is housed in a circuit board housing 19. The circuit board housing 19 includes a heat sink 191. In this embodiment, the circuit board housing 19 is made of heat dissipating material, and the heat sink 191 is disposed on the sidewall that contacts the control circuit board 18. The heat sink 191 includes heat dissipating fins 192 extending a certain length. The control circuit board 18 is connected to the heat sink 191 and can transfer heat generated by the control circuit board 18, dissipating the heat to the heat sink 191 and the heat dissipating fins 192. In this embodiment, the plane of the heat sink 191 is parallel to or coincides with the second plane S2. When the circuit board housing 19 is arranged in the first housing 111, in order to reduce the flow resistance of the cooling airflow and optimize the cooling effect, the extension direction of the space defined by adjacent fins is along the flow direction of the cooling airflow.

[0214] The first fan 216 is disposed at the end of the first drive shaft 211 near the output shaft 30. The first fan 216 is at least partially disposed within the housing 14. The second fan 226 is disposed at the end of the second drive shaft 221 near the output shaft 30. The second fan 226 is at least partially disposed within the housing 14. The circuit board housing 19 and the control circuit board 18 are disposed radially outward of the first and second fans 216, 226. Optionally, the circuit board housing 19 and the control circuit board 18 are disposed radially above the first and second fans 216, 226. The circuit board housing 19 and the control circuit board 18 are disposed within the first housing 111. The first air inlet 161 is disposed on the upper sidewall of the first housing 111. In this embodiment, the first air inlet 161 is disposed on the right and upper sidewalls of the first housing 111. It will be appreciated that the first air inlet 161 is partially located on the upper sidewall and partially located on the sidewall of the first housing 111 away from the output shaft 30. This allows for a longer heat dissipation path in contact with the circuit board housing 19. That is, the first air inlet 161 and the fan are basically located on the upper and lower sides and on the left and right sides of the control circuit board 18. The first air inlet 161 is configured as a matrix hole formed by multiple through holes to prevent the operator from accidentally inserting fingers or the like through the air flow opening.

[0215] Because the first fan 216 and the second fan 226 are substantially located within the housing 14, the housing 14 is provided with a first communication port 146 and a second communication port 147 corresponding to the first fan 216 and the second fan 226, respectively. In some embodiments, the positions of the first communication port 146 and the second communication port 147 are determined based on the positions of the first fan 216 and the second fan 226. Of course, the first communication port 146 and the second communication port 147 may also be omitted. This ensures that the cooling airflow entering through the first air inlet 161 and flowing through the control circuit board 18 is effectively utilized by the negative pressure generated by the rotation of the fans.

[0216] The airflow port also includes a first air outlet 162 for allowing heat dissipation air to flow out of the main housing 11. The first air outlet 162 connects the housing 14 and the first housing 111 to the external environment. In this embodiment, the air outlet of the first air outlet 162 is directed toward the front of the circular saw 100. Optionally, the second motor 22 is positioned closer to the front than the first motor 21. In some embodiments, airflow guide ribs are provided within the first housing 111 to guide the heat dissipation airflow so that the heat dissipation airflow flows within the confined space of the airflow guide ribs.

[0217] During cutting operation, with the bottom surface 51 of the base plate in contact with the workpiece, the control switch 81 is triggered normally, activating at least the first motor 21 and rotating the saw blade, thereby cutting the workpiece. Simultaneously, at least the first fan 216 rotates, creating negative pressure, driving outside air into the circular saw 100 to dissipate heat. After the fan rotates, the cooling airflow enters the first housing 111 through the first air inlet 161, initially flowing through the circuit board housing 19 and control circuit board 18, and then through the first communication port 146, the first motor 21, and the second motor 22, before exiting through the first air outlet 162.

[0218] In this embodiment, a second air outlet 163 is also included. The second air outlet 163 and the first air outlet 162 have different air outlet directions. In this embodiment, the second air outlet 163 is located near the second motor 22 and discharges air in a direction away from the cutting element 61. As a result, the heat dissipation airflow from the second air outlet 163 not only has a heat dissipation function but also has a dust-blowing function. Dust generated during the cutting process can be blown away. Optionally, the second air outlet 163 includes a third connecting port 164 configured to connect the housing 14, the first housing 111, and the outside world, and a fourth connecting port 165 provided on the side wall of the bottom plate 50 to also have a dust-blowing function. In this embodiment, the heat dissipation air path includes a first heat dissipation air path F1 and a second heat dissipation air path F2. The first heat dissipation air path F1 is configured so that when at least one of the first motor 21 and the second motor 22 is in operation, the heat dissipation airflow enters through the first air inlet 161, flows through the control circuit board 18 and the motor assembly 20, and then most of it flows out through the first air outlet 162. The second heat dissipation air path F2 is configured so that when at least one of the first motor 21 and the second motor 22 is running, the heat dissipation airflow enters from the first air inlet 161 , flows through the control circuit board 18 and the motor assembly 20 , and then most of it flows out from the second air outlet 163 .

[0219] In this embodiment, there is one circuit board housing 19, at least one controller, and the number of control circuit boards 18 corresponds to the number of controllers. Alternatively, multiple controllers may be provided on a single control circuit board 18. The circuit board housing 19 can accommodate at least one control circuit board 18. Multiple controllers are connected to each other via communication or electrical connections.

[0220] As shown in Figure 23, as an optional embodiment, the number of circuit board housings 19 is two, and the number of control circuit boards 18 is at least two. Using multiple control circuit boards 18 to configure multiple controllers can reduce the capacity requirements for the control circuit boards 18. The circuit board housings 19 are placed radially outside the first fan and the second fan. Optionally, the circuit board housing 19 and the control circuit board 18 are arranged radially above the first fan and the second fan 226. The circuit board housing 19 includes a first circuit board housing 19a and a second circuit board housing 19b. The structures of the first circuit board housing 19a and the second circuit board housing 19b can be the same to increase versatility. They can also be different, and the specific structures of the first circuit board housing 19a and the second circuit board housing 19b are specifically set according to the specific positions of the first circuit board housing 19a and the second circuit board housing 19b.

[0221] As shown in Figure 24, as an optional embodiment, the second plane S2 of the circuit board 18 is spatially perpendicular to the third plane S3. Optionally, in the direction perpendicular to the extension direction of the cutting member 61, the projection of the second plane S2 is a plane, and the projection of the third plane S3 is a straight line. The extension direction of the second plane S2 is parallel to the extension direction of the cutting member 61. Heat conduction occurs between the control circuit board 18 and the fixed shield. In this embodiment, the circuit board housing 19 is tightly attached to the fixed shield so that the heat of the circuit board housing 19 can be radiated and dissipated through the surface of the fixed shield, thereby increasing the heat dissipation path of the control circuit board 18.

[0222] Figure 25 shows a second embodiment of the heat dissipation solution. The control circuit board 18 is disposed between the motor assembly 20 and the battery pack 31. Optionally, the control circuit board 18 is disposed within the first housing 111 and between the storage housing and the battery compartment 15. In a direction perpendicular to the direction extending from the cutting member 61, the second plane S2 is a straight line, and the third plane S3 is a straight line, with the second plane S2 and the third plane S3 intersecting or perpendicular.

[0223] Among them, the structure of the motor assembly is the same as that of the first embodiment of the heat dissipation scheme. The circuit board housing 19 and the control circuit board 18 are arranged on the radial outside of the first fan 216 and the second fan 226. Optionally, the circuit board housing 19 and the control circuit board 18 are arranged on the radial rear side of the first fan 216 and the second fan 226, between the battery accommodating compartment 15 and the accommodating housing 14. The second air inlet 166 is provided in the battery accommodating compartment 15. In this embodiment, as shown in Figure 7, the battery accommodating compartment 15 includes at least one first outlet 151 for the battery pack 31 to enter and remove from the battery accommodating compartment 15, and a second outlet 152 that is different from the first outlet 151. As shown in Figures 7 and 25, the second air inlet 166 includes a first outlet 151, a second outlet 152 and a fifth connecting port 167 connecting the battery accommodating compartment 15 and the first housing 111. It can be understood that the fifth connecting port 167 is an air flow port for allowing the heat dissipation airflow to flow out of the battery accommodating compartment 15. To ensure more effective heat dissipation of the heat dissipation airflow, the fifth communication port 167 is disposed above the first fan 216 and the second fan 226 . The fifth communication port 167 is at least disposed below the first outlet 151 .

[0224] As shown in FIG7 , since the first fan 216 and the second fan 226 are substantially located within the housing 14 , a first communication port 146 and a second communication port 147 are provided on the housing 14 , corresponding to the first fan 216 and the second fan 226 , respectively. In some embodiments, the locations of the first communication port 146 and the second communication port 147 are specifically determined based on the positions of the first fan 216 and the second fan 226 . Of course, the first communication port 146 and the second communication port 147 may also be omitted. This ensures that cooling airflow entering through the second air inlet 166 and flowing through the battery pack 31 and the control circuit board 18 is effectively utilized by effectively utilizing the negative pressure generated by the rotation of the fans.

[0225] As shown in Figures 7 and 25, the air flow outlet also includes a first air outlet 162 for allowing the heat dissipation airflow to flow out of the main body housing 11. The first air outlet 162 connects the receiving housing 14 and the first housing 111 with the external environment. In this embodiment, the air outlet direction of the first air outlet 162 is toward the front side of the circular saw 100. Optionally, the second motor 22 is arranged closer to the front relative to the first motor 21. In some embodiments, airflow guide ribs are provided in the first housing 111, which are configured to guide the heat dissipation airflow so that the heat dissipation airflow flows within the confined space of the airflow guide ribs.

[0226] During cutting, with the bottom surface 51 of the base plate in contact with the workpiece, the control switch 81 is triggered normally, activating at least the first motor 21 and rotating the saw blade, thereby cutting the workpiece. Simultaneously, at least the first fan 216 rotates, creating negative pressure, driving outside air into the interior of the circular saw 100 to dissipate heat. After the fan rotates, the cooling airflow enters the battery compartment 15 and the first housing 111 through the second air inlet, flows through the battery pack 31, the circuit board housing 19, and the control circuit board 18, and flows through the first communication port 146, the first motor 21, and the second motor 22, before exiting through the first air outlet 162.

[0227] In this embodiment, a second air outlet 163 is also included. The air outlet direction of the second air outlet 163 is different from that of the first air outlet 162. In this embodiment, the second air outlet 163 is arranged near the second motor 22, and the second air outlet 163 discharges air in a direction away from the saw blade, so that the heat dissipation airflow of the second air outlet 163 has a dust blowing function in addition to the heat dissipation function. The dust generated during the cutting process can be blown away. Optionally, the second air outlet 163 includes a third connecting port 164 arranged to connect the receiving shell 14, the first shell 111 and the outside world, and a fourth connecting port 165 arranged on the side wall of the bottom plate 50 to take into account the dust blowing function. As shown in Figure 25, the air path includes a first heat dissipation air path F1 and a second heat dissipation air path F2. The first heat dissipation air path F1 is configured so that when at least one of the first motor 21 and the second motor 22 is running, the heat dissipation airflow enters from the second air inlet 166, flows through the battery pack 31, the control circuit board 18, and the motor assembly 20, and then most of it flows out from the first air outlet 162. The second heat dissipation air path F2 is configured so that when at least one of the first motor 21 and the second motor 22 is running, the heat dissipation airflow enters from the second air inlet 166 , flows through the battery pack 31 , the control circuit board 18 , and the motor assembly 20 , and most of it flows out from the second air outlet 163 .

[0228] In some embodiments, the circular saw 100 is provided with both a first air inlet 161 and a second air inlet 166 to allow for more efficient heat dissipation of the control circuit board 18 and the motor assembly 20 .

[0229] In this embodiment, there is one circuit board housing 19, at least one controller, and the number of control circuit boards 18 corresponds to the number of controllers. Alternatively, multiple controllers may be provided on a single control circuit board 18. The circuit board housing 19 can accommodate at least one control circuit board 18. Multiple controllers are connected to each other via communication or electrical connections.

[0230] As shown in Figure 26, as an optional embodiment, the number of circuit board housings 19 is two, and the number of control circuit boards 18 is at least two. Using multiple control circuit boards 18 to configure multiple controllers can reduce the capacity requirements for the control circuit boards 18. The circuit board housing 19 and the control circuit board 18 are arranged radially outside the first fan 216 and the second fan 226. Optionally, the circuit board housing 19 and the control circuit board 18 are arranged radially behind the first fan 216 and the second fan 226, between the battery accommodating compartment 15 and the accommodating housing 14. The circuit board housing 19 includes a first circuit board housing 19a and a second circuit board housing 19b. The structures of the first circuit board housing 19a and the second circuit board housing 19b can be the same to increase versatility. They can also be different, with the specific structures of the first circuit board housing 19a and the second circuit board housing 19b being specifically set according to the specific positions of the first circuit board housing 19a and the second circuit board housing 19b.

[0231] As shown in Figures 1 to 5, the cutting member 61 in this embodiment is a circular saw 100 blade having an outer diameter greater than 6 inches. In some embodiments, the circular saw 100 blade has an outer diameter ranging from approximately 6 inches to 12 inches. As shown in Figures 2 and 3, the projection of the center of gravity G of the circular saw 100 in a direction perpendicular to the cutting member 61 is located between the rear edge of the base plate 50 and the output axis 301. Optionally, as shown in Figure 2, this is the first state of the circular saw 100, at which time the fixed guard 62 is rotated to the minimum angle relative to the base plate 50 about the pivot axis 501. The ratio of the distance L1 between the projection of the center of gravity G of the circular saw 100 and the output axis 301 to the distance L2 from the rear edge of the base plate 50 to the output axis 301 is less than or equal to 1. In some embodiments, the ratio of the distance L1 between the projection of the center of gravity G of the circular saw 100 and the output axis 301 to the distance L2 between the rear edge of the base plate 50 and the output axis 301 is less than or equal to 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, or 0.2. The center of gravity G of the circular saw 100 is closer to the output axis 301 but remains behind the output axis 301, i.e., on the side of the output axis 301 closer to the grip 12. FIG. 3 shows the second state of the circular saw 100. In this state, when the fixed guard 62 is rotated to its maximum angle relative to the base plate 50 about the pivot axis 501, the distance L1' between the center of gravity of the circular saw 100 and the output axis 301 is minimized.

[0232] As shown in Figure 4, the cutting element 61 extends within a cutting plane S4, and the grip portion 12 is substantially symmetrically arranged about the first plane S1. In a direction perpendicular to the bottom surface 51 of the base plate, the projection of the first drive shaft 201 and the projection of the second drive shaft 202 have two endpoints that are farthest apart in the direction of the output axis 301. A width interval W is defined between two straight lines on the projection plane that pass through one endpoint, respectively, and are perpendicular to the output axis 301. The projection of the center of gravity G of the circular saw is disposed within the width interval W. In one embodiment, the first motor and the second motor are arranged radially and the first drive shaft and the second drive shaft are disposed parallel to each other. In a direction perpendicular to the bottom surface 51 of the base plate, the projections of the first drive shaft and the second drive shaft include a first endpoint closest to the cutting element and a second endpoint farthest from the cutting element. The first endpoint and the second endpoint are the extreme endpoints in the left-right direction of the circular saw when the first drive shaft and the second drive shaft are considered as a whole. A width interval W is defined between a line passing through the first endpoint and perpendicular to the output axis and a line passing through the second endpoint and perpendicular to the output axis. This width interval W represents the overall positional range of the circular saw within this width. In the fore-aft direction of the circular saw, this width interval does not solely encompass the fore-aft extent of the motor assembly, but rather the overall fore-aft extent of the circular saw. In one embodiment, when the first and second motors are arranged radially and the first and second drive shafts intersect, the projections of the first and second drive shafts perpendicular to the bottom surface 51 of the base plate include a first endpoint closest to the cutting element and a second endpoint furthest from the cutting element. The first and second endpoints represent the extreme left-right endpoints of the circular saw when the first and second drive shafts are considered as a single unit. A width interval W is defined between a line passing through the first endpoint and perpendicular to the output axis and a line passing through the second endpoint and perpendicular to the output axis. This width interval W represents the overall positional range of the circular saw within this width. In the fore-aft direction of the circular saw, this width interval does not solely encompass the fore-aft extent of the motor assembly, but rather the overall fore-aft extent of the circular saw.

[0233] In one embodiment, when the first and second motors are coaxially arranged, the projections of the first and second drive shafts, along a direction perpendicular to the bottom surface 51 of the base plate, include a first endpoint closest to the cutting element and a second endpoint furthest from the cutting element. The first and second drive shafts are arranged left and right in the circular saw's left-right direction, so the first endpoint is the leftmost end and the second endpoint is the rightmost end. A width interval W is defined between a line passing through the first endpoint and perpendicular to the output axis and a line passing through the second endpoint and perpendicular to the output axis. That is, width interval W is the positional range of the entire saw within this width. In the fore-aft direction of the circular saw, width interval W does not simply encompass the fore-aft range of the motor assembly, but rather encompasses the entire circular saw. This prevents undesirable handling of the circular saw 100 during operation, ensuring that the center of gravity of the circular saw is positioned within the width range of the first and second motors in the width direction, providing greater stability during operation.

[0234] In some embodiments, the projection of the center of gravity G of the circular saw 100, perpendicular to the bottom surface 51 of the base plate, is located between the projection of the cutting plane S4 and the right edge of the base plate projection. That is, the projection of the center of gravity G of the circular saw 100 is within the projection of the base plate, but does not extend beyond the left side of the cutting plane S4. Furthermore, the center of gravity G of the circular saw 100 is located near the first plane S1. Optionally, the distance from the projection of the center of gravity G of the circular saw 100 to the first plane S1 is less than the distance from the center of gravity G of the circular saw 100 to the cutting plane S4. Optionally, the ratio of the distance W1 between the projection of the center of gravity G of the circular saw 100 to the first plane S1 and the distance W2 from the cutting plane S4 to the first plane S1 is less than or equal to 1 / 3. In some embodiments, the center of gravity G of the circular saw 100 is preferably located on the first plane S1 to minimize the operational discomfort of the circular saw 100 during operation. Alternatively, the center of gravity G of the circular saw 100 may be located to the left or right of the first plane S1.

[0235] The bottom plate 50 is formed with a hole extending along the first direction K1 to allow the cutting member 61 to pass through the bottom plate 50. As shown in Figure 5, along the first direction K1, the ratio of the outer edge dimension L3 of the receiving housing 14 to the outer edge dimension La of the main body housing 11 is greater than or equal to 0.2 and less than or equal to 0.4. It will be appreciated that in some embodiments, the outer edge dimension L3 of the receiving housing 14 can be the same as the outer side dimension Lc of the receiving housing 14 along a direction perpendicular to the first drive shaft 211 and the second drive shaft 221.

[0236] As shown in FIG. 4 and FIG. 8 , along the direction of the output axis 301 , the ratio of the outer edge dimension H1 of the receiving housing 14 to the outer edge dimension Ha of the main housing 11 is greater than or equal to 0.15 and less than or equal to 0.4.

[0237] As shown in Figure 27, the controller 17 is configured to control the motor assembly 20. The controller 17 is configured to determine the start-up state of the first motor 21 and the second motor 22 according to a preset condition.

[0238] As an embodiment, the controller includes a first controller 171 and a second controller 172, that is, dual MCU control. In this embodiment, the first controller 171 includes a first power supply module, a first PWM drive control module and a first ADC (Analogue Digital Converter Unit) drive module. The second controller 172 includes a second power supply module, a second PWM drive control module and a second ADC (Analogue Digital Converter Unit) drive module. The battery pack 31 supplies power to the first controller 171 and the second controller 172 respectively. The first controller 171 is connected to the first motor 21, and the second controller 172 is connected to the second motor 22. It can be understood that the first controller 171 and the second controller 172 are connected in serial communication, but also have relatively independent control modules.

[0239] The first controller 171 collects electrical characteristic parameters such as phase current and bus voltage through the first ADC drive module, and sends the detected parameters to the first PWM drive control module of the first controller 171 in signal mode. The first PWM drive control module controls the start-up and operation of the first motor 21 through PWM signals. The second controller 172 collects electrical characteristic parameters such as phase current and bus voltage through the second ADC drive module, and sends the detected parameters to the first PWM drive control module of the second controller 172 in signal mode. The second PWM drive control module controls the start-up and operation of the second motor 22 through PWM signals. This is equivalent to providing two independent control circuits to control the first motor 21 and the second motor 22. Among them, the electrical characteristic parameters may also include parameters such as bus current, current storage time, and demagnetization time.

[0240] In this embodiment, the first motor 21 and the second motor 22 are respectively three-phase brushless motors. They include three-phase stator windings U, V, and W that are electronically commutated. In some embodiments, the three-phase stator windings U, V, and W are star-connected, and in other embodiments, the three-phase stator windings U, V, and W are delta-connected. However, it must be understood that other types of brushless motors are also within the scope of the present disclosure. The brushless motor may include less than or more than three phases. The drive circuit is electrically connected to the stator windings U, V, and W of the motor and is configured to transfer current from the battery pack 31 to the stator windings U, V, and W to drive the motor to rotate.

[0241] As shown in Figure 29, the specific control process is as follows:

[0242] S210: The control switch 81 is activated.

[0243] During operation, the first controller 171 detects that the control switch 81 is activated, that is, receives a start signal.

[0244] S220: The first motor meets the starting condition. If so, execute S240; if not, execute S230.

[0245] S230: The first motor does not start, and the second motor does not start.

[0246] S240: The first motor starts, and the second motor does not start.

[0247] The first controller 171 controls the first motor 21 to start at a first preset step length.

[0248] S250: The operation of the first motor meets a preset condition, for example, the speed is greater than a first preset speed. If so, execute S260; if not, execute S240.

[0249] S260: Send a second motor start signal.

[0250] S270: The second motor meets the starting conditions. If yes, execute S290; if not, execute S280

[0251] S280: The first motor starts, and the second motor does not start.

[0252] S290: The first motor is started, the second motor is started, and they operate under preset conditions, for example, they operate at full duty cycle respectively.

[0253] The first controller 171 sends a signal to the second controller that controls the second motor 22, so that the second controller starts the second motor 22. The second controller 172 controls the second motor 22 to start at a second preset step length. The second preset step length is greater than or equal to the first preset step length to shorten the startup time of the two motors. In this embodiment, after the first motor 21 starts stably, the first motor 21 operates at a full duty cycle. After the second motor 22 starts stably, both the first motor 21 and the second motor 22 operate at a full duty cycle. It can be understood that the change in motor speed can be obtained by modulation and calculation of the motor's electrical characteristic parameters, such as phase current. The full duty cycle does not necessarily refer to a duty cycle of 100%. The full duty cycle refers to the maximum duty cycle specified in the product performance, which can be a duty cycle of 90%, a duty cycle of 80%, etc.

[0254] S300: The control switch is released, and S230 is executed. The first motor and the second motor are not started.

[0255] As an embodiment, as shown in FIG28 , the controller 17 includes a first controller 171 and a second controller 172 . The first controller 171 and the second controller 172 are disposed on the same control circuit board 18 , or are placed on different control circuit boards but are communicatively connected. The first controller 171 controls the first motor 21 , and the second controller 172 controls the second motor 22 . In this embodiment, the first controller 171 and the second controller 172 communicate serially. A driver is also provided, including a first drive circuit 173 a and a second drive circuit 173 b . The first drive circuit 173 a is connected to the first controller 171 and the battery pack 31 . The second drive circuit 173 b is connected to the second controller 172 and the battery pack 31 . In other words, the battery pack 31 is connected to the drive circuit, which supplies power to the controller via the drive circuit.

[0256] In this embodiment, the first motor 21 and the second motor 22 are each a three-phase brushless motor. Each motor includes three-phase stator windings U, V, and W that are electronically commutated. In some embodiments, the three-phase stator windings U, V, and W are connected in a star configuration. In other embodiments, the three-phase stator windings U, V, and W are connected in a delta configuration. However, it should be understood that other types of brushless motors are also within the scope of this disclosure. Brushless motors may include fewer than or more than three phases.

[0257] Taking the first drive circuit 173a as an example, the drive circuit 173a is electrically connected to the stator windings U, V, and W of the motor and is configured to transfer current from the battery pack 31 to the stator windings U, V, and W to drive the motor to rotate. The first drive circuit 173a includes multiple switching elements Q1, Q2, Q3, Q4, Q5, and Q6. The gate terminal of each switching element is electrically connected to the first controller 171 and is configured to receive control signals from the first controller 171. The drain or source terminal of each switching element is connected to the stator windings U, V, and W of the first motor 21. The switching elements Q1-Q6 receive control signals from the first controller 171 to change their respective conduction states, thereby changing the current applied by the battery pack 31 to the stator windings U, V, and W of the first motor 21. In one embodiment, the first drive circuit 173a may be a three-phase bridge driver circuit including six controllable semiconductor power devices (e.g., FETs, BJTs, IGBTs, etc.). In some embodiments, the drive circuit 173a may also include more than six controllable semiconductor power devices. It is understandable that the above-mentioned switching element may also be any other type of solid-state switch, such as an insulated gate bipolar transistor (IGBT), a bipolar junction transistor (BJT), etc.

[0258] The controller specifically controls the on / off state of the switching elements in the drive circuit by controlling the chip. In some embodiments, the controller controls the ratio between the on-time and off-time of the drive switch based on a pulse width modulation (PWM) signal. In this embodiment, the first controller 171 includes a first PWM drive control module. The second controller 172 includes a second PWM drive control module.

[0259] The first controller 171 further includes a first ADC driver module, which collects electrical characteristic parameters such as phase current and bus voltage through the first ADC driver module. The second controller 172 further includes a second ADC driver module, which collects electrical characteristic parameters such as phase current and bus voltage through the first ADC driver module.

[0260] When the power circuit between the battery pack 31 and the drive circuit is connected, the drive circuit transmits the current from the battery pack 31 to the controller. Specifically, the first drive circuit 173a transmits the current to the first controller 171, and the second drive circuit 173b transmits the current to the second controller 172. The first controller 171 detects preset parameters using the first ADC drive module and sends the detected parameters as a signal to the first PWM drive control module of the first controller 171. The first PWM drive control module sends a PWM control signal to the first drive circuit 173a, which controls the ratio between the on-time and off-time of the drive switch based on the PWM control signal. The second controller 172 detects preset parameters using the second ADC drive module and sends the detected parameters as a signal to the second PWM drive control module of the second controller 172. The first PWM drive control module sends a PWM control signal to the second drive circuit 173b, which controls the ratio between the on-time and off-time of the drive switch based on the PWM control signal. The preset parameters include phase current, bus voltage, bus current, current storage time, demagnetization time, and other parameters. The preset parameters detected by the first controller 171 and the preset parameters detected by the second controller 172 may be the same or different.

[0261] As shown in Figure 30, the specific control process is as follows:

[0262] S411: The control switch 81 is activated.

[0263] During operation, the first controller 171 detects that the control switch 81 is activated, that is, receives a start signal.

[0264] S412: The first motor meets the starting condition. If so, execute S141; if not, execute S413.

[0265] S413: The first motor does not start, and the second motor does not start.

[0266] S414: The first motor starts, and the second motor does not start.

[0267] The first controller 171 controls the first motor 21 to start.

[0268] S415: The operation of the first motor meets the first preset condition, for example, the speed is greater than the first preset speed. If so, execute S414; if not, execute S416 and S417.

[0269] Taking speed as an example, the first controller 171 first determines the relationship between the speed of the first motor 21 and a first speed threshold. If the speed of the first motor 21 exceeds the first speed threshold, the first motor 21 maintains its current operating state and drives the output shaft 30, and the second motor 22 does not need to be started. Optionally, the first speed threshold is 5000 RPM.

[0270] S416: The second motor starts and operates under the second preset condition.

[0271] Optionally, the second motor 22 enters a hot standby state, i.e., the second motor is started and maintained in a ready state for operation under a second preset condition. Optionally, still using the speed as an example, the second preset speed is less than the first speed threshold, and the second preset speed is the speed at which the second motor achieves optimal output efficiency. Optionally, the second preset speed is 4500 RPM.

[0272] S417: The operation of the first motor meets the second preset condition, for example, the rotation speed is greater than the second preset rotation speed. If so, execute S415; if not, execute S418.

[0273] S418: The second motor operates at the third preset condition, and the first motor operates at the second preset condition.

[0274] When the speed of the first motor 21 is less than the second preset speed, the second motor 22 is started and operated according to the third preset condition. Simultaneously, the first motor 21 is controlled to output at the second preset speed. Optionally, the third preset condition is to control the second motor 22 to operate at a maximum duty cycle upon completion of startup. The first motor operates at a constant speed at the second preset speed. In other words, at this point, both the first motor 21 and the second motor 22 begin driving the output shaft, thus entering dual-motor mode.

[0275] S419: The operation of the first motor meets the fourth preset condition, for example, the rotation speed is less than the fourth preset rotation speed. If so, execute S420; if not, execute S418.

[0276] The speed of the first motor is continuously detected during operation. When the operation of the first motor 21 meets a fourth preset condition, optionally, the speed is not less than the fourth preset speed, it is determined that the output torque of the motor assembly can meet the current required torque of the output shaft. Optionally, the fourth preset speed is less than the second preset speed, for example, the fourth preset speed is 3500 RPM.

[0277] S420: The first motor and the second motor are respectively operated at full duty cycle.

[0278] When the speed is less than the fourth predetermined speed, it is determined that the output torque of the motor assembly needs to be increased, and the first motor 21 and the second motor 22 are controlled to operate at full duty cycle. The maximum duty cycle of the first motor 21 and the maximum duty cycle of the second motor 22 may be the same or different.

[0279] To avoid frequent switching between single and dual motor modes, in actual applications, in dual motor mode, if the speed is higher than 5000 RPM and the current is lower than the current threshold for a preset time, it will switch to single motor operation.

[0280] S421: The control switch is released, and S413 is executed. The first motor and the second motor are not started.

[0281] Figures 31 to 38 illustrate a power tool according to another embodiment. The power tool is similar to the power tool described above with reference to Figures 1 to 30 . Therefore, features and elements corresponding to those of the power tool are given similar reference numerals followed by the letter "h." Furthermore, the following description primarily focuses on the differences between the control elements and control methods of the power tool with respect to the motor assembly 20h.

[0282] Referring to Figure 31 , the power tool includes a housing 10h, functional components 60h, and an operating element 80h. The housing 10h forms the main body of the power tool, connecting or supporting the aforementioned components and forming a housing space that can accommodate or partially accommodate other components. The functional component 60h is the component of the power tool that actually performs operations such as cutting, tightening, grinding, and impacting. For example, in the electric circular saw 100, the functional component 60h is the cutting element 61, which is a circular saw blade. Other power tools may also have functional components 60h such as chains or drill bits. The operating element 80h is operated by the user to switch the power tool on and off and can output corresponding start or stop signals. For example, the operating element 80h allows the user to start or stop the motor assembly 40, which will be described later, and outputs a start signal indicating that the motor assembly 40 is desired to start operating, or a stop signal indicating that the motor assembly 40 is desired to stop operating, to the controller 60, which will be described later. In some cases, the operating member 80h may have more diverse functions, such as allowing the user to adjust the motor speed or perform other functions. In some embodiments, the operating member 80h may be a control switch 81 such as a trigger or other mechanical switch. It is understood that starting and stopping the power tool can also be achieved using methods other than providing the operating member 80h on the tool body. For example, in some embodiments, the user may also transmit a signal to the power tool via an external device such as a mobile phone or tablet computer to start or stop the power tool.

[0283] Referring to Figures 32 to 35 , the power tool includes, in addition to a housing 10h, functional components 60h, and operating components 80h, a motor assembly 20h, a power supply 31, and a controller 17h. The motor assembly 20h serves as the prime mover of the power tool. When the motor shaft of the motor assembly 20h rotates, it directly or indirectly drives the functional components 60h mounted on the output shaft 30h to operate. In this application, the power tool is configured with at least two motors, namely, the motor assembly 20h includes at least a first motor 21h and a second motor 22h. The first motor 21h and the second motor 22h drive the same output shaft 30h. There is a transmission relationship between the first motor 21h and the second motor 22h. In other words, when the first motor 21h rotates, it can drive the second motor 22h to rotate.

[0284] FIG33 illustrates an alternative configuration of a motor assembly 20h, wherein the first and second motors 21h and 22h are inner rotor motors, and the motor shafts of the first and second motors 21h and 22h are parallel to the output shaft 30h. A gear train can be used to transmit power between the motor shafts and the output shaft 30h. FIG34 illustrates another alternative configuration of a motor assembly 20h, wherein the first and second motors 21h and 22h are inner rotor motors, and the motor shafts of the first and second motors 21h and 22h are collinear with the output shaft 30h. A clutch assembly 42h can also be provided between the first and second motors 21h and 22h. The clutch assembly 42h has a first state that allows power transmission between the first and second motors 21h and 22h, and a second state that prevents power transmission between the first and second motors 21h and 22h. The clutch assembly 42h can be either mechanical or electronic. The following text will primarily illustrate the technical solution using the motor assembly 20h as comprising a first motor 21h and a second motor 22h. At least one of the first motor 21h and the second motor 22h is capable of driving a functional component 60h to perform operations such as cutting, fastening, grinding, and impacting. The following text will primarily describe scenarios in which both the first motor 21h and the second motor 22h are in operation. It will be appreciated that the structures of the first motors 21, 21e, 21f, and 21g, as well as the first motors 22, 22e, 22f, and 22g described in Figures 12 to 19 are also applicable to this embodiment.

[0285] The power supply 31 provides electrical energy for at least the above-mentioned motor assembly 20h, and can also provide power for other related components such as the controller 17h. In some embodiments, the power supply 31 is a battery pack, which is detachably connected to the power tool. In other embodiments, the power supply 31 can also be implemented using AC power, AC power, and related circuits such as a power adapter, transformer, rectifier, and voltage stabilizer.

[0286] The controller 17h can be an MCU (Microcontroller Unit), an ARM (Advanced Reduced Instruction Set Computing Machine), a DSP (Digital Signal Processor), or the like. By running a related program, the controller 17h can control the motor assembly 20h to operate as intended. Referring to FIG5 , the power tool further includes a drive device 173h connected between the controller 17h and the motor assembly 20h. After running the motor control program, the controller 17h can output control signals such as pulse-width modulation (PWM) signals to the drive device 173h. The drive device 173h can convert the control signals into drive signals that ultimately drive the motor, thereby transmitting the electrical energy provided by the power supply 31 to the motor assembly 20h via the DC bus.

[0287] In some embodiments, the drive device 173h includes a first drive circuit 1731h connected between the controller 17h and the first motor 21h, and a second drive circuit 1732h connected between the controller 17h and the second motor 22h. The first drive circuit 1731h and the second drive circuit 1732h may include a three-phase bridge circuit, comprising three switches serving as the upper half bridge and three switches serving as the lower half bridge. In the first drive circuit 1731h, the upper half bridge switches Q1, Q3, and Q5 are respectively connected between the power supply terminal of the power supply 31 and the respective phase coils of the first motor 21h, while the lower half bridge switches Q2, Q4, and Q6 are respectively connected between the respective phase coils of the first motor 21h and the ground line. The same applies to the second drive circuit 1732h and the second motor 22h. The switches may be field-effect transistors or insulated gate bipolar transistors. In other examples, the drive device 173h may also be an integrated driver chip, etc.

[0288] Furthermore, as shown in FIG36 , in some embodiments, there may be more than one controller 17h in hardware. For example, a power tool may include a first controller 171h and a second controller 172h, with the first and second controllers 171h and 172h exchanging data via an electrical connection or other means. The first controller 171h controls the operation of the first motor 21h and transmits a first control signal to a first drive circuit 1731h, which is connected between the first controller 171h and the first motor 21h. The second controller 172h controls the operation of the second motor 22h and transmits a second control signal to a second drive circuit 1732h, which is connected between the second controller 172h and the second motor 22h. In other embodiments, the first and second controllers 171h and 172h may be dual controllers at the software level, for example, the first and second controllers 171h and 172h being dual VCPUs hosted on the same hardware, or being first and second control units designed in a program, including parallel processes or threads.

[0289] Continuing from the previous discussion, since the controller 17h needs to make a preliminary judgment on the initial position of the motor's rotor when starting the motor, and the power tool is equipped with a first motor 21h and a second motor 22h, and there is a transmission relationship between the first and second motors 21h and 22h, the rotation of one motor will drive the rotation of the other motor, and when controlling the motors to start, there will be a problem that the rotor positions of the two motors affect each other. To address this problem, in one embodiment, the controller 17h can control the first and second motors 21h and 22h to start simultaneously. In response to the start signal from the operating member 80h or other signal used to start the power tool, the controller 17h will simultaneously output corresponding control signals to the first drive circuit 1731h corresponding to the first motor 21h and the second drive circuit 1732h corresponding to the second motor 22h. In some embodiments, the first controller 171h outputs a first control signal to the first drive circuit 1731h to drive the first motor 21h, and the second controller 171h outputs a second control signal to the second drive circuit 1732h to drive the second motor 22h. The first and second controllers 171h and 172h synchronize signals before outputting the control signals to ensure that the first and second motors 21h and 22h are activated simultaneously. In another embodiment, the controller 17h can also use a time-sharing method to activate the motor assembly 20h, eliminating the need for signal synchronization and ensuring safe motor startup during peak hours.

[0290] In response to a start signal from the operating member 80h or other signal for starting the power tool, the controller 17h will first control the first motor 21h to start, and then control the second motor 22h to start based on the back electromotive force generated by the second motor 22h after the first motor 21h is started. Specifically, the first motor 21h begins to rotate after being started by the controller 17h. The rotation of the rotor of the first motor 21h will drive the rotor of the second motor 22h, which has not yet started, to rotate. The passive rotation of the rotor of the second motor 22h will generate electromagnetic induction with the stator winding of the second motor 22h, generating a back electromotive force in the second motor 22h. The controller 17h will control the second motor 22h to start after the first motor 21h is started based on the back electromotive force of the second motor 22h. It should be noted that in this embodiment, the second motor 22h can be a brushless motor, which does not have a position sensor such as a Hall sensor that can directly detect the rotor position. The controller 17h therefore controls the start-up of the second motor 22h by detecting the back electromotive force of the second motor 22h. Of course, if the second motor 22h is equipped with a position sensor, the controller 17h can also use the above method as an alternative solution to start the second motor 22h.

[0291] It is understood that the first motor 21h can be a sensorless brushless motor or a sensored brushless motor. Accordingly, there are multiple optional implementation methods for the controller 17h to control the first motor 21h to start up first, and this application does not impose specific limitations on this. In some embodiments, the controller 17h can use a pulse injection method to estimate the initial rotor position of the first motor 21h and control its startup. The controller 17h can inject pulses into each of the six electrical angle sectors of the first motor 21h, that is, transmit corresponding pulse signals to the six switching transistors in the first drive circuit 1731h. Then, the controller 17h detects the current response of the first motor 21h to the pulse injection and determines the initial rotor position of the first motor 21h based on the current response. The initial rotor position can then be used to control the startup of the first motor 21h. In other embodiments, the controller 17h can also use a high-frequency injection method to control the startup of the first motor 21h. In still other embodiments, the controller 17h can also control the startup of the first motor 21h by capturing the edge of the Hall signal.

[0292] In some embodiments, after controlling the start of the first motor 21h, the controller 17h may wait for a first preset time period before detecting and controlling the start of the second motor 22h based on the back electromotive force of the second motor 22h. Specifically, after the first motor 21h starts and the first preset time period has passed, the first motor 21h continues to rotate and has reached a certain speed. The back electromotive force of the second motor 22h driven by the first motor 21h is also in a state that can be detected more accurately and can be used for startup control. At this point, the controller 17h can estimate the rotor position of the second motor 22h based on the back electromotive force of the second motor 22h and control its startup. If the first preset time period is too short, the first and second motors 21h and 22h interfere with each other, affecting the startup of both. If it is too long, the first motor 21h has a significant impact on the rotation of the second motor 22h, making the startup control of the second motor 22h difficult. Therefore, it is necessary to set a first preset time period of appropriate value. In some embodiments, the first preset time period is greater than or equal to 0.1s and less than or equal to 2s.

[0293] In other embodiments, after controlling the first motor 21h to start, the controller 17h can detect the speed of the first motor 21h, and after the speed of the first motor 21h reaches the first speed threshold, it can detect and control the start of the second motor 22h based on the back electromotive force of the second motor 22h. Specifically, after the first motor 21h starts and reaches the first speed threshold, the back electromotive force of the second motor 22h driven by the first motor 21h is also in a state that can be detected more accurately and can be used for startup control. At this time, the controller 17h can estimate the rotor position of the second motor 22h based on the back electromotive force of the second motor 22h and control its startup. In some embodiments, the above-mentioned first speed threshold is greater than or equal to 10RPM or greater than or equal to 10% of the no-load speed of the first motor 21h.

[0294] There are multiple optional implementations for the controller 17h to control the startup of the second motor 22h based on the back electromotive force of the second motor 22h, and this application does not impose specific restrictions on this. In some embodiments, the controller 17h can detect the extreme value of the back electromotive force of the second motor 22h, that is, detect the maximum or minimum value of the back electromotive force of the second motor 22h, and deduce the rotor position from the extreme value position of the back electromotive force of the second motor 22h, and then perform startup control. In other embodiments, the controller 17h can also detect the relative relationship between the back electromotive force of the second motor 22h and the zero point potential, and deduce the rotor position from the zero point position of the back electromotive force of the second motor 22h, and then perform startup control.

[0295] Continuing from the foregoing, the power tool is provided with a first controller 171h and a second controller 172h, which respectively control the start-up of the first motor 21h and the second motor 22h. In response to a start signal from the operating member 80h or other signal for starting the power tool, the first controller 171h can first control the start-up of the first motor 21h, and then the second controller 172h can control the start-up of the second motor 22h based on the back electromotive force of the second motor 22h. In some cases, after the first controller 171h executes the start-up program for the first motor 21h in response to the relevant start-up signal, it can send a notification to the second controller 172h to initiate the start-up program for the second motor 172h. In other cases, the first and second controllers 171h and 172h can spontaneously execute the start-up programs for the first and second motors 21h and 22h, respectively, in response to the relevant start-up signals. In some embodiments, the first controller 171h may notify the second controller 172h after controlling the first motor 21h to start and waiting for a first preset time period. After receiving the notification, the second controller 172h may control the second motor 22h to start based on the back electromotive force of the second motor 22h. In other embodiments, the first controller 171h may notify the second controller 172h after controlling the first motor 21h to start and detecting that the speed of the first motor 21h reaches a first speed threshold. After receiving the notification, the second controller 172h may control the second motor 22h to start based on the back electromotive force of the second motor 22h. In still other embodiments, the first controller 171h may notify the second controller 172h after controlling the first motor 21h to start. After receiving the notification, the second controller 172h waits for the first preset time period or detects that the speed of the first motor 21h reaches the first speed threshold before controlling the second motor 22h to start based on the back electromotive force of the second motor 22h. In some further embodiments, the first controller 171h can control the first motor 21h to start after receiving a relevant start signal, and the second controller 172h can control the second motor 22h to start after receiving the relevant start signal, then wait for a first preset time period or detect that the speed of the first motor 21h reaches a first speed threshold, based on the back electromotive force of the second motor 22h. It is understood that in the case of dual controllers, whether there is mutual notification between the controllers and which controller 17h performs timing statistics or speed detection are not the focus of the present application and do not affect the scope of protection of this application.

[0296] In addition, this application does not limit the specific control method of the controller 17h to drive the motor to operate after the motor is started. It can use a six-step commutation method to control the operation of the motor component 20h, or it can use an FOC method to control the operation of the motor component 20h. Of course, other motor control methods can also be adaptively introduced.

[0297] Correspondingly, a control method for an electric tool is proposed, which is applied to the electric tool described above. Referring to FIG37 , a flow chart of the control method for the electric tool is shown, which may include the following steps:

[0298] S710, starting the first motor of the electric tool 21h;

[0299] S720, the controller 17h of the power tool controls the start of the second motor 22h based on the back electromotive force of the second motor 22h of the power tool after the first motor 21h is started; there is a transmission relationship between the first motor 21h and the second motor 22h, and when the first motor 21h rotates, it drives the second motor 22h to rotate.

[0300] Continuing from the previous discussion, since the first and second motors 21h and 22h share the same power supply 31 for power supply, if the first and second motors 21h and 22h are controlled to shut down for protection simultaneously, the current peaks during their shutdown protection will be superimposed on the bus, potentially damaging semiconductor components and interfering with the judgment of related control logic. To address this issue, the controller 17h can set different protection thresholds for different motors to achieve time-sharing shutdown protection of the motor assembly 20h, thereby staggering peak loads and ensuring safe motor shutdown.

[0301] The controller 17h can control the first motor 21h to shut down when the first motor parameter of the first motor 21h exceeds the first protection threshold, and control the second motor 22h to shut down when the second motor parameter of the second motor 22h exceeds the second protection threshold. The first protection threshold and the second protection threshold are not equal in value, and there is a certain time interval between the moment when the first motor parameter exceeds the first protection threshold and the moment when the second motor parameter exceeds the second protection threshold. It is assumed that the first motor parameter exceeds the first protection threshold before the second motor parameter exceeds the second protection threshold for the purpose of exemplary description. However, it is understandable that by adjusting the values ​​of the first and second protection thresholds, the first motor 21h can be shut down first, and the second motor 22h can also be shut down first, which does not affect the scope of protection of this application.

[0302] It should be noted that the motor parameters of the first and second motors 21h and 22h may be of various parameter types, and the protection thresholds may also be of various threshold types. However, there is a corresponding relationship between the two, i.e., the corresponding protection thresholds are used to determine whether the corresponding motor parameters are exceeded. Furthermore, in the above scheme, the first and second motor parameters to be compared and determined sequentially should be of the same parameter type. That is, it is not necessary to first determine whether a first motor parameter of one parameter type exceeds its corresponding first protection threshold, and then determine whether a second motor parameter of another parameter type exceeds its corresponding second protection threshold.

[0303] In some embodiments, the first motor parameter includes a first stall parameter, and the first protection threshold includes a corresponding first stall threshold. Conversely, the second motor parameter includes a second stall parameter, and the second protection threshold includes a corresponding second stall threshold. The first and second stall thresholds are numerically unequal. The controller 17h first detects that the first stall parameter of the first motor 21h exceeds the first stall threshold and controls the first motor 21h to shut down. The controller 17h then detects that the second stall parameter of the second motor 22h exceeds the second stall threshold and controls the second motor 22h to shut down.

[0304] In some embodiments, the stall parameter is a commutation duration, the first stall parameter is a first commutation duration of the first motor 21h, the first stall threshold is a first duration threshold, the second stall parameter is a second commutation duration of the second motor 22h, and the second stall threshold is a second duration threshold. The ratio of the commutation durations of the two motors is related to their rotational speeds. If the rotational speed ratio of the first and second motors 21h and 22h driving the same output shaft 30h is n:1, or in other words, the ratio of the transmission ratio between the first motor 21h and the output shaft 30h and the transmission ratio between the second motor 22h and the output shaft 30h is n:1, then their first and second commutation durations should theoretically be 1:n. Assuming that the first and second duration thresholds are also set to be 1:n, the stall shutdown protection of the first and second motors 21h and 22h will be activated simultaneously, which will lead to the aforementioned current peak superposition and component damage. Therefore, in this application, if the speed ratio of the first and second motors 21h and 22h is n:1, the ratio of the first and second time thresholds will be set in the controller 17h to be not equal to 1:n, so that the stall shutdown protection of the first and second motors 21h and 22h will not be carried out at the same time, thereby staggering the current peaks and avoiding component damage and control interference.

[0305] For example, assuming the speed ratio of the first and second motors 21h and 22h is n:1, the first and second time thresholds can be set to 0.95*1:1.05*n. When the power tool stalls, the controller 17h will first detect that the first commutation duration of the first motor 21h exceeds the first time threshold and control the first motor 21h to shut down. After a period of time, the controller 17h will detect that the second commutation duration of the second motor 22h exceeds the second time threshold and control the second motor 22h to shut down. In other words, the speed ratio of the first and second motors 21h and 22h is n:1. If the ratio of the first and second time thresholds is less than 1:n, the controller 17h will control the first motor 21h and the second motor 22h to shut down in sequence for stall protection. If the ratio of the first and second time thresholds is greater than 1:n, the controller 17h will control the second motor 22h and the first motor 21h to shut down in sequence for stall protection.

[0306] In other embodiments, the first motor parameter also includes a first overcurrent parameter, and the first protection threshold includes a corresponding first overcurrent threshold. Conversely, the second motor parameter also includes a second overcurrent parameter, and the second protection threshold includes a corresponding second overcurrent threshold. The first and second overcurrent thresholds are numerically unequal. The controller 17h will first detect that the first overcurrent parameter of the first motor 21h exceeds the first overcurrent threshold and control the first motor 21h to shut down. It will then detect that the second overcurrent parameter of the second motor 22h exceeds the second overcurrent threshold and control the second motor 22h to shut down.

[0307] In some embodiments, the overcurrent parameter is a motor current, including but not limited to the bus current, phase current, and quadrature-axis current of the motor. The first overcurrent parameter is the first current of the first motor 21h, the first overcurrent threshold is the first current threshold, and the second overcurrent parameter is the second current of the second motor 22h, and the second overcurrent threshold is the second current threshold. The ratio of the current amplitudes of the two motors is related to their output torques. If the torque ratio of the first and second motors 21h and 22h driving the same output shaft 30h is n:1, then their current amplitudes should theoretically be n:1. Assuming that the first and second current thresholds are also set to n:1, the overcurrent shutdown protection of the first and second motors 21h and 22h will be activated simultaneously, which will lead to the aforementioned problems of superposition of current peaks and damage to components. Therefore, in this application, if the torque ratio of the first and second motors 21h and 22h is n:1, the ratio of the first and second current thresholds will be set in the controller 17h to be not equal to n:1, so that the overcurrent shutdown protection of the first and second motors 21h and 22h will not be performed at the same time, thereby staggering the current peaks and avoiding component damage and control interference.

[0308] For example, assuming the torque ratio of the first and second motors 21h and 22h is n:1, the first and second current thresholds can be set to 0.95*1:1.05*n. When an overcurrent occurs in the power tool, the controller 17h will first detect that the first current of the first motor 21h exceeds the first current threshold and control the first motor 21h to shut down. After a period of time, the controller 17h will detect that the second current of the second motor 22h exceeds the second current threshold and control the second motor 22h to shut down. In other words, the torque ratio of the first and second motors 21h and 22h is n:1. If the ratio of the first and second current thresholds is less than n:1, the controller 17h will control the first motor 21h and the second motor 22h to shut down in sequence for overcurrent protection. If the ratio of the first and second current thresholds is greater than n:1, the controller 17h will control the second motor 22h and the first motor 21h to shut down in sequence for overcurrent protection.

[0309] In yet other embodiments, the overcurrent parameter may include a calculated value of one or more of the motor's output torque, current, and demagnetization time. For example, the overcurrent parameter may be the motor's output torque, the motor's current, or the product of the motor's current and the demagnetization time. Similar to the above, different forms of overcurrent parameters each have a corresponding overcurrent threshold, and the controller 17h compares and determines the overcurrent parameters in the same form.

[0310] In summary, when the first and second motors 21h and 22h drive the same output shaft, if the first and second motor parameters of the same parameter type related to the shutdown protection theoretically have a proportional relationship, then when the ratio of the first and second motor parameters is n:1, the ratio of the first and second protection thresholds corresponding to the first and second motor parameters set in the power tool controller 17h does not conform to the above n:1 relationship, and the ratio of the two is not equal to n:1, thereby achieving the purpose of the above-mentioned peak-shifting shutdown protection.

[0311] In some embodiments, the first and second protection thresholds used by the controller 17h can be adaptively adjusted based on parameters such as the capacity and voltage of the power supply 31. When the capacity and voltage of the power supply 31 are different, the first protection threshold used by the controller 17h in the power tool is different, and / or the second protection threshold used is different. In some embodiments, the first and second protection thresholds used by the controller 17h can be negatively correlated with the capacity or voltage of the power supply 31. For example, if the capacity or voltage of the power supply 31 equipped with the power tool is higher, the first and second duration thresholds used by the controller 17h are correspondingly lowered to more sensitively detect stalls when the power supply 31 has a stronger power supply capacity. In other embodiments, the first and second protection thresholds used by the controller 17h can also be positively correlated with the capacity or voltage of the power supply 31.

[0312] In other embodiments, the first and second protection thresholds used by the controller 17h may be dynamic thresholds, and the first and / or second protection thresholds may be related to the current and voltage of the motor assembly 20h. The first protection threshold may dynamically change with the current and voltage of the first motor 21h, and the second protection threshold may dynamically change with the current and voltage of the second motor 22h. In some embodiments, the first and second duration thresholds used by the controller 17h may be negatively correlated with the current and voltage of the first and second motors 21h and 22h, respectively. As the current and voltage of the first and second motors 21h and 22h increase, the first and second duration thresholds may be dynamically and adaptively adjusted downward.

[0313] Continuing from the previous section, the power tool is equipped with a first controller 171h and a second controller 172h, which are responsible for the shutdown protection of the first motor 21h and the second motor 22h, respectively. The first controller 171h can detect a first motor parameter of the first motor 21h and control the first motor 21h to shut down when the first motor parameter exceeds a first protection threshold. The second controller 172h can detect a second motor parameter of the second motor 22h and control the second motor 22h to shut down when the second motor parameter exceeds a second protection threshold. The first protection threshold and the second protection threshold are not numerically equal, and there is a certain time interval between the time when the first controller 171h controls the first motor 21h to shut down and the time when the second controller 172h controls the second motor 22h to shut down.

[0314] Correspondingly, a control method for an electric tool is proposed, which is applied to the electric tool described above. Referring to FIG38 , the control method for the electric tool is shown, which may include the following steps:

[0315] S810: When a first motor parameter of a first motor 21h of the power tool exceeds a first protection threshold, the controller 17h of the power tool controls the first motor 21h to stop.

[0316] S820, the controller 17h controls the second motor 22h to stop when the second motor parameter of the second motor 22h of the power tool exceeds the second protection threshold after the first motor parameter exceeds the first protection threshold; the first protection threshold and the second protection threshold are not equal, and the first motor 21h and the second motor 22h drive the same output shaft 30h.

[0317] Continuing from the above, to address the problem of current peak superposition during shutdown protection described above, the controller 17h can also control the first motor 21h to shut down when the first motor parameter of the first motor 21h exceeds the first protection threshold, and control the second motor 22h to shut down after the first motor parameter exceeds the first protection threshold and a second preset time has passed, thereby achieving time-sharing shutdown of the first and second motors 21h and 22h in a more simplified manner. However, the above-mentioned single threshold plus delay method, once the shutdown protection of the first motor 21h has a logical fault, will interfere with the shutdown protection of the second motor 22h, and then cause the problem of both motors being unable to stop. It is also necessary to cooperate with other protection logics for optimization, and usually returns to the solution described above that uses the first and second protection thresholds for peak-shifting protection.

[0318] The above shows and describes the basic principles, main features and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of this application.

Claims

1. An electric tool comprising: An output shaft is configured to output torque; the output shaft rotates around the output axis; a first motor including a first drive shaft that rotates about a first axis; A second motor includes a second drive shaft rotating around a second axis; the first drive shaft and the second drive shaft are arranged along the radial direction of the first drive shaft; A power transmission mechanism, transmitting power of at least one of the first motor and the second motor to the output shaft; the torque of the first drive shaft and the second drive shaft is output through the output shaft; A housing shell is configured to house a first motor and a second motor; when observed by orthographic projection along the extending direction of the output shaft, along the direction of the line connecting the first axis and the second axis, an outer dimension Lc of the housing shell is greater than an outer diameter dimension D of any one of the motors; The host housing includes a first marking structure corresponding to the first motor and a second marking structure corresponding to the second motor, the first marking structure is configured to indicate that the power tool is provided with a first motor, and the second marking structure is configured to indicate that the power tool is provided with a second motor.

2. The electric tool according to claim 1, wherein: The first driving shaft is arranged in parallel with the second driving shaft.

3. The electric tool according to claim 1, wherein: In the direction of the output axis, the first motor at least partially overlaps with the second motor.

4. The electric tool according to claim 1, wherein: The housing shell includes a first housing portion for housing the first motor and a second housing portion for housing the second motor; the first housing portion at least supports a first bearing portion of the first motor away from the output shaft, and the second housing portion at least supports a second bearing portion of the second motor away from the output shaft.

5. The electric tool according to claim 1, further comprising: A first shell, the receiving shell is formed or connected to the first shell, and the first shell is formed or connected with a gripping portion for grasping; a guard assembly configured to receive a cutting member at least partially driven by the output shaft; The shield assembly and the receiving shell are basically located on two sides of the first shell.

6. The electric tool according to claim 5, wherein: The power transmission mechanism is accommodated in the first housing and is located outside the accommodation housing.

7. The electric tool according to claim 1, further comprising a DC power supply, the DC power supply supplies power to the first motor and the second motor; the nominal voltage of the DC power supply is greater than or equal to 18V.

8. The electric tool according to claim 7, wherein: The DC power supply includes at least one battery pack.

9. The electric tool according to claim 1, wherein: The first motor includes a first stator, a first rotor and a coil winding disposed on the first stator, and the first drive shaft is formed or connected to the first rotor; the second motor includes a second stator, a second rotor and a coil winding disposed on the second stator; The second drive shaft is formed or connected to the second rotor.

10. The electric tool according to claim 8, wherein: The first motor and the second motor are configured to have at least one different first parameter, and the first parameter includes: maximum output speed, maximum output torque, stator core outer diameter, stator core inner diameter, rotor core outer diameter, rotor core inner diameter, rotor pole thickness, stator pole thickness, air gap length, core length, stator pole pair number, stator pole corresponding arc, rotor pole pair number and rotor pole corresponding arc.

11. The electric tool according to claim 1, wherein: The first marking structure and the second marking structure are formed or connected on the outer wall surface of the host housing.

12. The electric tool according to claim 11, wherein: The first marking structure and the second marking structure are configured as mutually independent double-barrel structures.

13. The electric tool according to claim 11, wherein: The first marking structure includes a first display portion, and the second marking structure includes a second display portion. The first display portion and the second display portion are respectively arranged at positions on the host housing that are easily visible.

14. The electric tool according to claim 13, wherein: The first display unit includes a light emitting body, and the light emitting body at least indicates the on / off status of the first motor.

15. The electric power tool according to claim 13, wherein: The first display portion includes an icon representing the first motor, the second display portion includes an icon representing the second motor, and the first display portion and the second display portion are respectively provided with a back adhesive layer.

16. An electric tool comprising: An output shaft is configured to output torque; the output shaft rotates around the output axis; a first motor including a first drive shaft that rotates about a first axis; A second motor includes a second drive shaft rotating around a second axis; the first drive shaft and the second drive shaft are arranged along the radial direction of the first drive shaft; A power transmission mechanism, transmitting power of at least one of the first motor and the second motor to the output shaft; the torque of the first drive shaft and the second drive shaft is output through the output shaft; The housing shell is configured to house the first motor and the second motor. When observed in the orthographic projection along the extension direction of the output shaft, along the direction of the line connecting the first axis and the second axis, the ratio of the outer dimension Lc of the housing shell to the outer diameter dimension D of any one of the motors is greater than or equal to 1.

1.

17. An electric tool comprising: An output shaft is configured to output torque; the output shaft rotates around the output axis; a first motor including a first drive shaft that rotates about a first axis; A second motor includes a second drive shaft rotating around a second axis; the first drive shaft and the second drive shaft are arranged along the radial direction of the first drive shaft; A power transmission mechanism, transmitting power of at least one of the first motor and the second motor to the output shaft; the torque of the first drive shaft and the second drive shaft is output through the output shaft; A receiving shell, configured to receive the first motor and the second motor; The host housing includes a first marking structure corresponding to the first motor and a second marking structure corresponding to the second motor, and the first marking structure and the second marking structure are formed or connected on the outer wall surface of the host housing; the first marking structure is configured to indicate that the power tool is provided with a first motor, and the second marking structure is configured to indicate that the power tool is provided with a second motor.

18. The electric power tool according to claim 17, wherein: The first marking structure and the second marking structure are arranged on the outer wall of a housing shell configured to accommodate the first motor and the second motor, the first marking structure is configured to include a shape similar to the outline of the first motor part; the second marking structure is configured to include a shape similar to the outline of the second motor part.

19. The electric power tool according to claim 17, wherein: The first marking structure includes a display screen, and the display screen indicates the operating status of the first motor.

20. The electric power tool according to claim 17, wherein: The second marking structure includes at least one of a light emitting body or a display screen, and is configured to indicate the operating status of the second motor.

21. An electric tool comprising: An output shaft is configured to output torque; the output shaft rotates around the output axis; a first motor including a first drive shaft that rotates about a first axis; a second electric machine including a second drive shaft that rotates about a second axis; a power transmission mechanism for transmitting power of at least one of the first motor and the second motor to the output shaft; The torque of the first drive shaft and the second drive shaft is output through the output shaft; The power transmission mechanism comprises: A transmission assembly is arranged between at least one of the first motor and the second motor and the output shaft; the transmission assembly at least includes a speed reduction mechanism; A clutch assembly is disposed between the first motor and the second motor, and the clutch assembly is configured to limit or allow at least one of the first drive shaft or the second drive shaft to drive the output shaft under preset conditions.

22. The electric power tool according to claim 21, wherein: The transmission assembly is configured to connect at least one of the first drive shaft and the second drive shaft to the clutch assembly.

23. The electric power tool according to claim 21, wherein: The transmission assembly includes a first gear assembly, which connects the first motor and the output shaft, and the first gear assembly provides at least one reduction ratio.

24. The electric power tool according to claim 23, wherein: The transmission assembly includes a second gear assembly, wherein the second gear assembly connects the second motor and the output shaft, and the second gear assembly is configured to provide at least one reduction ratio.

25. The power tool according to claim 21, wherein: The clutch assembly includes a one-way transmission member operable to connect the first motor and the second motor for rotation in a first rotation direction, and to decouple the first motor and the second motor for rotation in a second rotation direction.

26. The power tool according to claim 24, wherein: The clutch assembly connects the second gear assembly and the output shaft.

27. The power tool according to claim 23, wherein: The clutch assembly includes a third gear, the first gear set includes a first driven wheel, the third gear is meshed with the first driven wheel, and a transmission ratio between the third gear and the first driven wheel is substantially 1.

28. The electric power tool according to claim 26, wherein: The clutch assembly includes an idler shaft that rotates around a clutch axis, and the second gear set includes a second driven wheel arranged on the idler shaft. When the rotation speed of the idler shaft is greater than the rotation speed of the output shaft, the clutch assembly drives the output shaft to rotate at the rotation speed of the idler shaft.

29. The electric power tool according to claim 28, wherein: A non-thrust bearing is disposed at the first end of the idler shaft, and an elastic member is disposed at one end of the non-thrust bearing.

30. The power tool according to claim 24, wherein: At least one of the first gear assembly and the second gear assembly includes a helical gear.

31. An electric tool comprising: An output shaft is configured to output torque; the output shaft rotates around the output axis; a first motor including a first drive shaft that rotates about a first axis; a second electric machine including a second drive shaft that rotates about a second axis; a power transmission mechanism for transmitting power of at least one of the first motor and the second motor to the output shaft; The torque of the first drive shaft and the second drive shaft is output through the output shaft; The power transmission mechanism comprises: A transmission assembly is arranged between at least one of the first motor and the second motor and the output shaft; the transmission assembly at least includes a speed reduction mechanism; In orthographic projection observation along the extension direction of the output shaft, the projection of the first axis and the projection of the second axis are located above the projection of the output axis.

32. The electric power tool according to claim 31, wherein: In orthographic projection observation along the direction of the output axis, an angle α between a line connecting the projection of the first axis and the projection of the output axis and a line connecting the projection of the second axis and the projection of the output axis is greater than or equal to 45° and less than or equal to 180°.

33. A cutting tool comprising: An output shaft, configured to mount a cutting member; The cutting member rotates around the output axis; Motor assembly, including: a first motor including a first drive shaft that rotates about a first axis; a second electric machine including a second drive shaft that rotates about a second axis; a first fan supported by at least one of the first drive shaft, the second drive shaft, and the output shaft; a power transmission mechanism for transmitting power of at least one motor in the motor assembly to the output shaft; A mainframe housing, accommodating the motor assembly and the power transmission mechanism; an air flow port is formed on the mainframe housing; A control circuit board, comprising a controller configured to control the motor assembly; the control circuit board is disposed in the host housing; When the first fan rotates, a heat dissipation air path can be generated, and the heat dissipation air path at least flows through the control circuit board and the motor assembly.

34. The cutting tool according to claim 33, wherein The first fan is supported by the first driving shaft and driven by the first motor to rotate and generate heat dissipation airflow; The cutting tool also includes: a second fan, which is supported by the second drive shaft and driven by the second motor to rotate to generate a heat dissipation airflow. When the second fan rotates, it can generate a heat dissipation air path, and the heat dissipation air path at least flows through the control circuit board and the motor assembly.

35. The cutting tool of claim 34, wherein: The airflow port includes a first air inlet and a first air outlet. The heat dissipation airflow enters the host housing from the first air inlet and flows out of the host housing from the first air outlet.

36. The cutting tool of claim 35, wherein: The air flow port further includes a second air outlet, and the heat dissipation airflow flows out of the host housing from at least one of the first air outlet and the second air outlet, and the first air outlet and the second air outlet have different air outlet directions.

37. The cutting tool of claim 35, wherein: The host shell includes a first shell and a receiving shell, wherein the first shell forms or is connected with a receiving shell, the receiving shell is configured to receive the first motor and the second motor, the control circuit board is disposed in the first shell, and the first air inlet allows the heat dissipation airflow to enter the receiving shell from the first shell.

38. The cutting tool of claim 37, wherein: The first air outlet communicates with the receiving shell and the first shell.

39. The cutting tool of claim 36, further comprising: A bottom plate is movably connected to the main body housing, and the bottom plate is formed with a bottom surface that contacts the workpiece; The second air outlet is disposed on the bottom plate and discharges air toward a side direction of the bottom plate.

40. The cutting tool of claim 39, wherein: The heat dissipation air path includes a first heat dissipation air path and a second heat dissipation air path. The first heat dissipation air path is configured so that when at least one of the first motor or the second motor is in operation, the heat dissipation airflow enters from the first air inlet, flows through the control circuit board and the motor assembly, and then most of the heat dissipation airflow flows out from the first air outlet; the second heat dissipation air path is configured so that when at least one of the first motor or the second motor is in operation, the heat dissipation airflow enters from the first air inlet, flows through the control circuit board and the motor assembly, and then most of the heat dissipation airflow flows out from the second air outlet.

41. The cutting tool according to claim 35 further includes a circuit board housing configured to accommodate the control circuit board, the circuit board housing including a heat sink connected to the control circuit board and capable of transferring heat generated by the control circuit board, and the circuit board housing is arranged radially outside the motor assembly.

42. The cutting tool of claim 41, further comprising: The fixed shield is arranged to at least partially surround the cutting piece; the extension direction of the control circuit board is parallel to the extension direction of the cutting piece, and heat conduction occurs between the control circuit board and the fixed shield.

43. The cutting tool of claim 41, wherein: At least one control circuit board is provided, and the circuit board housing can accommodate at least one control circuit board.

44. The cutting tool of claim 34, further comprising: The power supply includes at least one battery pack configured to provide an energy source for the motor assembly; the battery pack is arranged between the motor assembly and a gripping portion for grasping, and the main housing is provided with a semi-open battery accommodating compartment formed by an inward recess.

45. The cutting tool of claim 44, wherein: When any one of the first fan and the second fan rotates, a heat dissipation air path can be generated, and the heat dissipation air path at least flows through the battery pack, the control circuit board and the motor assembly.

46. ​​The cutting tool of claim 45, wherein: The airflow port includes a second air inlet and a first air outlet. After the heat dissipation airflow enters the battery accommodating compartment and the main body shell from the second air inlet, it flows out of the main body shell from the first air outlet.

47. The cutting tool according to claim 45 further includes a circuit board housing configured to accommodate the control circuit board, the circuit board housing including a heat sink connected to the control circuit board and capable of transferring heat generated by the control circuit board, the circuit board housing being disposed between the motor assembly and the battery housing compartment.

48. A circular saw comprising: An output shaft is configured to mount a cutting member; the cutting member rotates about the output axis; a first motor including a first drive shaft that rotates about a first axis; a second electric machine including a second drive shaft that rotates about a second axis; a power transmission mechanism for transmitting power of at least one of the first motor and the second motor to the output shaft; A power supply, comprising at least one battery pack configured to provide an energy source for the motor; A main body housing at least partially accommodates the first motor, the second motor and the power transmission mechanism; the main body housing includes a first housing, and the first housing is formed with or connected to a gripping portion for gripping; A bottom plate is movably connected to the main body housing, and the bottom plate is formed with a bottom surface that contacts the workpiece; In an orthographic projection observation along a direction perpendicular to the extension direction of the cutting member, the projection of the center of gravity of the circular saw is located between the rear edge of the base plate and the output axis.

49. The circular saw of claim 48, wherein: The projection of the center of gravity of the circular saw is close to the output axis and is located at the rear side of the output axis.

50. The circular saw of claim 48, wherein: The cutting member extends in a cutting plane; the gripping portion is basically symmetrically arranged about a first plane; along a direction perpendicular to the base plate, the projection of the center of gravity of the circular saw is located between the cutting plane and the right edge of the base plate or basically on the first plane.

51. The circular saw of claim 50, wherein: The distance from the projection of the center of gravity of the circular saw to the first plane is smaller than the distance from the center of gravity of the circular saw to the cutting plane.

52. The circular saw of claim 50, wherein: A ratio of a distance W1 between a projection of the center of gravity of the circular saw and the first plane and a distance W2 between the cutting plane and the first plane is less than or equal to 1 / 3.

53. The circular saw of claim 48, wherein: The first motor, the second motor, the battery pack and the gripping portion are arranged on the same side of the cutting member, and the battery pack is at least partially arranged behind the first motor and the second motor, and the battery pack is at least partially arranged in front of the gripping portion.

54. The circular saw of claim 48, wherein: The first shell is formed or connected with a receiving shell, and the receiving shell is configured to receive the first motor and the second motor.

55. The circular saw of claim 54, wherein: The bottom plate is formed with a hole extending along a first direction so that the cutting piece can pass through the bottom plate. Along the first direction, the ratio of the outer edge dimension L3 of the receiving shell to the outer edge dimension La of the main shell is greater than or equal to 0.2 and less than or equal to 0.

4.

56. The circular saw of claim 54, wherein: Along the output axis direction, the ratio of the outer edge dimension H1 of the receiving shell to the outer edge dimension Ha of the main body shell is greater than or equal to 0.15 and less than or equal to 0.

4.

57. The circular saw of claim 54, wherein: The cutting element has an outer diameter greater than 6 inches.

58. A circular saw comprising: An output shaft is configured to mount a cutting member; the cutting member rotates about the output axis; a first motor including a first drive shaft that rotates about a first axis; a second electric machine including a second drive shaft that rotates about a second axis; a power transmission mechanism for transmitting power of at least one of the first motor and the second motor to the output shaft; A power supply, comprising at least one battery pack configured to provide an energy source for the motor; A main body housing, at least partially accommodating the first motor, the second motor and the power transmission mechanism; A bottom plate is movably connected to the main body housing, and the bottom plate is formed with a bottom surface that contacts the workpiece; In the orthographic projection observation along the direction perpendicular to the bottom surface of the base plate, the projection of the first drive axis and the projection of the second drive axis have two endpoints that are farthest apart along the output axis direction, and a width interval W is defined between two straight lines on the projection plane that pass through one of the endpoints respectively and are perpendicular to the output axis, and the projection of the center of gravity of the circular saw is set within the width interval W.

59. A circular saw comprising: An output shaft is configured to mount a cutting member; the cutting member rotates about the output axis; a first motor including a first drive shaft that rotates about a first axis; A second motor comprises a second drive shaft rotating about a second axis; the second drive shaft is coaxially arranged with the first drive shaft; the first motor and the second motor are mechanically coupled; a power transmission mechanism for transmitting power of at least one of the first motor and the second motor to the output shaft; A power supply, comprising at least one battery pack configured to provide an energy source for the motor; The motor diameter of the first motor is less than or equal to 70 mm, and the motor diameter of the second motor is less than or equal to 70 mm.

60. The circular saw of claim 59, wherein: The first motor is an outer rotor motor, and the second motor is an outer rotor motor.

61. The circular saw of claim 59, wherein: The first drive shaft rotates synchronously with the second drive shaft.

62. The circular saw of claim 61, wherein: The first motor includes a first stator and a first rotor, and the first drive shaft is formed or connected to the first rotor; the second motor includes a second stator and a second rotor; and the second drive shaft is formed or connected to the second rotor.

63. The circular saw according to claim 62, further comprising a motor fixing portion connected to the first stator and the second stator, respectively.

64. The circular saw of claim 63, wherein: The motor fixing portion is provided with a receiving channel, and the receiving channel is configured to receive at least a portion of the first driving shaft and the second driving shaft.

65. The circular saw of claim 64, wherein: The receiving channel at least partially overlaps with the first stator along the first axis direction, and the receiving channel at least partially overlaps with the second stator along the first axis direction.

66. The circular saw of claim 59, wherein: In the direction along the output axis, the projection of the first axis and the projection of the second axis are located above the projection of the output axis.

67. The circular saw of claim 66, wherein: The power transmission mechanism includes a transmission assembly, and the transmission assembly includes at least a reduction mechanism.

68. The circular saw of claim 66, further comprising: A bottom plate, wherein the bottom plate is formed with a bottom surface of the bottom plate in contact with the workpiece; When observing in an orthographic projection in a direction perpendicular to the bottom surface of the base plate, the projection of the first drive axis and the projection of the second drive axis have two endpoints that are farthest apart in the direction of the output axis. A width interval W is defined between two straight lines on the projection plane that pass through each of the endpoints and are perpendicular to the output axis. The projection of the center of gravity of the circular saw is set within the width interval W.

69. An electric tool comprising: Functional parts; A motor assembly, comprising a first motor and a second motor, wherein at least one of the first motor and the second motor drives the functional part to operate; A power supply device, connected to the motor assembly, at least to supply power to the motor assembly; Among them, there is a transmission relationship between the first motor and the second motor, and the second motor is driven to rotate when the first motor rotates; the electric tool also includes: a controller connected to the motor assembly, and the controller is configured to control the start-up of the second motor based on the back electromotive force of the second motor after the first motor is started.

70. The power tool according to claim 69, wherein: The second motor is a sensorless brushless motor.

71. The power tool according to claim 69, wherein: The controller is configured to control the first motor to start when receiving a signal to start the electric tool.

72. The power tool according to claim 69, wherein: The controller is configured to control the second motor to start based on the back electromotive force of the second motor after the first motor starts and a first preset time period has passed.

73. The power tool according to claim 72, wherein: The first preset time length is greater than or equal to 0.1 s and less than or equal to 2 s.

74. The power tool according to claim 69, wherein: The controller is configured to control the second motor to start based on a back electromotive force of the second motor after the first motor starts and the speed of the first motor reaches a first speed threshold.

75. The power tool according to claim 74, wherein: The first speed threshold is greater than or equal to 10 RPM or greater than or equal to 10% of the no-load speed of the first motor.

76. The power tool according to claim 72 or 74, wherein: The controller is configured to determine the rotor position of the second motor based on an extreme value of the back electromotive force of the second motor or based on a relative relationship between the back electromotive force of the second motor and a zero potential, and control the start-up of the second motor.

77. The power tool according to claim 69, wherein: The controller includes a first controller and a second controller, the first controller is connected to the first motor, and the second controller is connected to the second motor; the first controller is configured to control the first motor to start when receiving a signal to start the electric tool; The second controller is configured to control starting of the second motor based on a back electromotive force of the second motor after starting of the first motor.

78. A method for controlling an electric tool, comprising: Starting a first motor of the electric tool; The controller of the electric tool controls the start of the second motor of the electric tool based on the back electromotive force of the second motor of the electric tool after the first motor is started; There is a transmission relationship between the first motor and the second motor, and when the first motor rotates, the second motor is driven to rotate.

79. An electric tool comprising: Functional parts; A motor assembly, comprising a first motor and a second motor, wherein at least one of the first motor and the second motor drives the functional part to operate; A power supply device, connected to the motor assembly, at least to supply power to the motor assembly; Wherein, the first motor and the second motor drive the same output shaft; The electric tool also includes: a controller connected to the motor assembly, the controller being configured to control the first motor to stop when a first motor parameter of the first motor exceeds a first protection threshold, and to control the second motor to stop when a second motor parameter of the second motor exceeds a second protection threshold after the first motor parameter exceeds the first protection threshold; the first protection threshold is not equal to the second protection threshold.

80. The power tool according to claim 79, wherein: The first motor parameter includes a first stall parameter of the first motor, and the first protection threshold includes a first stall threshold; the second motor parameter includes a second stall parameter of the second motor, and the second protection threshold includes a second stall threshold.

81. The power tool according to claim 79, wherein: The first motor parameter includes a first overcurrent parameter of the first motor, and the first protection threshold includes a first overcurrent threshold; the second motor parameter includes a second overcurrent parameter of the second motor, and the second protection threshold includes a second overcurrent threshold.

82. The power tool according to claim 80, wherein: The first stall parameter is a first commutation duration of the first motor, and the first stall threshold is a first duration threshold; the second stall parameter is a second commutation duration of the second motor, and the second stall threshold is a second duration threshold; The controller is configured to control the first motor to stop when the first commutation duration exceeds the first duration threshold, and control the second motor to stop when the second commutation duration exceeds the second duration threshold after the first commutation duration exceeds the first duration threshold; The first duration threshold is different from the second duration threshold.

83. The power tool according to claim 82, wherein: When the speed ratio of the first motor to the second motor is n:1, the ratio of the first duration threshold to the second duration threshold is not equal to 1:n.

84. The power tool according to claim 81, wherein: The first overcurrent parameter is the first current of the first motor, and the first overcurrent threshold is the first current threshold; the second overcurrent parameter is the second current of the second motor, and the second overcurrent threshold is the second current threshold; The controller is configured to control the first motor to stop when the first current exceeds the first current threshold, and control the second motor to stop when the second current exceeds the second current threshold after the first current exceeds the first current threshold; The first current threshold is different from the second current threshold.

85. The power tool according to claim 84, wherein: When the torque ratio of the first motor to the second motor is n:1, the ratio of the first current threshold to the second current threshold is not equal to n:

1.

86. The power tool according to claim 81, wherein: The first overcurrent parameter is the calculated value of one or more of the first output torque, first current, and first demagnetization time of the first motor; the second overcurrent parameter is the calculated value of one or more of the second output torque, second current, and second demagnetization time of the second motor.

87. The power tool according to claim 79, wherein: When the ratio of the first motor parameter to the second motor parameter is n:1, the ratio of the first protection threshold to the second protection threshold is not equal to n:

1.

88. The power tool according to claim 80 or 81, further comprising: The driving device comprises a first driving circuit and a second driving circuit, wherein the first driving circuit is connected between the power supply device and the first motor, and the second driving circuit is connected between the power supply device and the second motor.

89. The power tool according to claim 88, wherein: The first protection threshold has different values ​​when the capacity or voltage of the power supply device is different; and / or the second protection threshold has different values ​​when the capacity or voltage of the power supply device is different.

90. The power tool according to claim 88, wherein: The first protection threshold and / or the second protection threshold are dynamic thresholds and the values ​​thereof have a corresponding relationship with the current current or voltage of the motor component.

91. The power tool according to claim 88, wherein: The controller includes a first controller and a second controller, the first controller is connected to the first motor through the first drive circuit, and the second controller is connected to the second motor through the second drive circuit; The first controller is configured to control the first motor to stop when a first motor parameter of the first motor exceeds a first protection threshold; The second controller is configured to control the second motor to stop when a second motor parameter of the second motor exceeds a second protection threshold after the first motor parameter exceeds the first protection threshold; The first protection threshold is different from the second protection threshold.

92. An electric tool comprising: Functional parts; A motor assembly, comprising a first motor and a second motor, wherein at least one of the first motor and the second motor drives the functional part to operate; A power supply device, connected to the motor assembly, at least to supply power to the motor assembly; Wherein, the first motor and the second motor drive the same output shaft; The electric tool also includes: a controller connected to the motor assembly, the controller being configured to control the first motor to stop when a first motor parameter of the first motor exceeds a first protection threshold, and to control the second motor to stop after the first motor parameter exceeds the first protection threshold and a second preset time has passed.

93. A method for controlling an electric tool, comprising: The controller of the electric tool controls the first motor to stop when a first motor parameter of the first motor of the electric tool exceeds a first protection threshold; The controller controls the second motor to stop when a second motor parameter of the second motor of the electric tool exceeds a second protection threshold after the first motor parameter exceeds the first protection threshold; The first protection threshold value is different from the second protection threshold value, and the first motor and the second motor drive the same output shaft.

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