Power tool

Abstract

The application discloses an electric tool, comprising a first motor, a second motor, a power transmission mechanism, a transmission assembly and a clutch assembly. The first motor comprises a first driving shaft rotating around a first axis. The second motor comprises a second driving shaft rotating around a second axis. The power transmission mechanism transmits power of at least one of the first motor and the second motor to an output shaft, and torque of the first driving shaft and the second driving shaft is output through the output shaft. The 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 comprises a speed reduction mechanism, and the speed reduction mechanism provides at least one speed reduction ratio. The clutch assembly is arranged between the first motor and the second motor, and the clutch assembly is used for limiting or allowing at least one of the first driving shaft or the second driving shaft to drive the output shaft under a preset condition. The electric tool adopts two motors to cooperate more stably.

Description

Technical Field

[0001] This application relates to an electric tool, specifically an electric tool. Background Technology

[0002] In related technologies, power tools typically require their output mechanisms to operate under both light and heavy load conditions. To enable the power tool to output higher torque for heavy loads, it usually incorporates a high-power, high-torque motor. This high-power motor can drive the output mechanism to handle larger loads. However, when the power tool is under light load, the high-power motor consumes a significant amount of power, resulting in substantial waste. This also causes the motor's operating efficiency to decrease under light loads, impacting the power tool's lifespan.

[0003] This section provides background information related to this application, which is not necessarily prior art. Summary of the Invention

[0004] One objective of this application is to solve or at least alleviate some or all of the aforementioned problems. Therefore, one objective of this application is to provide an electric tool that uses two motors in cooperation to drive an output shaft for output operation.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] An electric tool includes: an output shaft for outputting torque; the output shaft rotating about an output axis; a first motor including a first drive shaft rotating about a first axis; a second motor including a second drive shaft rotating about a second axis; a power transmission mechanism for transmitting power from at least one of the first and second motors to the output shaft, wherein the torques of the first drive shaft and the second drive shaft are output through the output shaft; the power transmission mechanism includes: a transmission assembly disposed between at least one of the first and second motors and the output shaft; the transmission assembly including at least a reduction mechanism; and a clutch assembly disposed between the first and second motors, the clutch assembly being used to restrict or allow at least one of the first or second drive shafts to drive the output shaft under preset conditions.

[0007] 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.

[0008] 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.

[0009] In some embodiments, the transmission assembly includes a second gear assembly that connects a second motor to an output shaft, and the second gear assembly provides at least one reduction ratio.

[0010] In some embodiments, the clutch assembly includes a one-way drive that is operable to engage the rotation of a first motor and a second motor in a first rotational direction, and to disengage the rotation of the first motor and the second motor in a second rotational direction.

[0011] In some embodiments, the clutch assembly connects the second gear assembly to the output shaft.

[0012] In some embodiments, the clutch assembly includes a third gear, the first gear set includes a first driven gear, the third gear meshes with the first driven gear, and the transmission ratio between the third gear and the first driven gear is substantially 1.

[0013] In some embodiments, the clutch assembly has an idler shaft that rotates about the clutch axis, and the second gear set includes a second driven gear disposed on the idler shaft. When the rotational speed of the idler shaft is greater than the rotational speed of the output shaft, the clutch assembly drives the output shaft to rotate at the rotational speed of the idler shaft.

[0014] In some embodiments, a non-thrust bearing is provided at the first end of the idler shaft, and an elastic element is provided at the other end of the non-thrust bearing.

[0015] In some embodiments, at least one of the first gear assembly and the second gear assembly includes a helical gear.

[0016] The beneficial effects of this application are as follows: the clutch assembly is configured between the first motor and the second motor, and the clutch assembly is used to restrict or allow at least one of the first drive shaft or the second drive shaft to drive the output shaft under preset conditions, so that the first motor and the second motor can drive the output shaft to work in their respective high motor efficiency ranges; the transmission assembly with reduction and torque increase is provided to improve the cutting ability of the power tool and improve the working efficiency of the power tool; the coupling of the motor assembly allows the power tool to be used in both light load and high load conditions; at the same time, the performance requirements of the motor in the motor assembly are reduced, so that a small diameter motor can be used to achieve the performance requirements of a large motor, which not only reduces costs, but also reduces the requirements for machine heat dissipation and other aspects. Attached Figure Description

[0017] Figure 1 This is a perspective structural diagram of a circular saw according to an embodiment of this application;

[0018] Figure 2 This is a structural diagram of a circular saw in the first state according to an embodiment of this application;

[0019] Figure 3This is a structural diagram of a circular saw in the second state according to an embodiment of this application;

[0020] Figure 4 This is a structural diagram of a circular saw according to another embodiment of this application, showing relevant components of the motor assembly;

[0021] Figure 5 This is a partial component structure diagram of a circular saw from a third perspective of an embodiment of this application, with the cutting-related components removed;

[0022] Figure 6 yes Figure 5 A partial view of the AA section view;

[0023] Figure 7 This is an exploded view of some components of a circular saw according to an embodiment of this application;

[0024] Figure 8 This is a half-sectional view of the motor assembly and housing of a circular saw according to an embodiment of this application;

[0025] Figure 9 This is a perspective structural diagram of another example of a circular saw according to one embodiment of this application;

[0026] Figure 10 This is a perspective view of a third example of a circular saw according to an embodiment of this application;

[0027] Figure 11 This is a cross-sectional view of the first motor in the motor assembly of this application;

[0028] Figure 12 This is a schematic diagram of the internal structure of a circular saw according to an embodiment of this application;

[0029] Figure 13 This is a schematic diagram of a portion of the structure of a circular saw according to an embodiment of this application;

[0030] Figure 14 yes Figure 13 A partial sectional view of the middle structure;

[0031] Figure 15 Is with Figure 12 A structural diagram of another example with a different structure;

[0032] Figure 16 Is with Figure 12 A structural diagram of the third example with a different structure;

[0033] Figure 17 Is with Figure 12 A structural diagram of the fourth example with a different structure;

[0034] Figure 18 Is with Figure 12 Structural diagram of the fifth example with different structures

[0035] Figure 19 This is a schematic diagram of the power transmission mechanism of a circular saw according to an embodiment of this application;

[0036] Figure 20 yes Figure 19 Another structural diagram from a different perspective;

[0037] Figure 21 yes Figure 20 A schematic diagram of a partial cross-sectional view from another perspective;

[0038] Figure 22 yes Figure 20 Another structural diagram from a different perspective;

[0039] Figure 23 This is a schematic diagram of the structure of a second power transmission mechanism for a circular saw according to an embodiment of this application;

[0040] Figure 24 This is a schematic diagram of the structure of a third power transmission mechanism for a circular saw according to an embodiment of this application;

[0041] Figure 25 This is a schematic diagram of the structure of a fourth type of motor assembly, power transmission mechanism and housing of a circular saw according to an embodiment of this application;

[0042] Figure 26 yes Figure 25 A structural schematic diagram of the motor assembly and power transmission mechanism from another perspective;

[0043] Figure 27 This is a schematic diagram of the electrical structure of one embodiment of this application;

[0044] Figure 28 This is a schematic diagram of another electrical structure according to an embodiment of this application;

[0045] Figure 29 This is a control flowchart of an embodiment of this application;

[0046] Figure 30 This is another control flowchart of an embodiment of this application. Detailed Implementation

[0047] Before explaining any implementation of this application in detail, it should be understood that this application is not limited to its application to the structural details and component arrangements set forth in the following description or shown in the above drawings.

[0048] In this application, the terms "comprising," "including," "having," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0049] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "and / or" relationship.

[0050] In this application, the terms "connection," "combination," "coupling," and "installation" can 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 the need for an intermediary, while an indirect connection refers to two parts or components each being connected to at least one intermediary, with the connection achieved through the intermediary. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0051] In this application, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are to include the values ​​and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to 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. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.

[0052] In this application, those skilled in the art will understand that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0053] In this application, the directional terms "upper," "lower," "left," "right," "front," and "rear" are used to describe the orientation and positional relationships shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when an element is mentioned as being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "below" can include directly below, lower left, lower right, lower front, and lower rear.

[0054] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. When using the unit "controller," "processor," "central processing unit," "CPU," or "MCU" to perform a specific function, unless otherwise stated, these functions may be performed by a single or multiple of the aforementioned units.

[0055] In this application, the terms "device," "module," or "unit" are used to describe devices that can be implemented in hardware or software to perform a specific function.

[0056] In this application, the terms “calculation,” “judgment,” “control,” “determine,” “identify,” etc., refer to the operation and process of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0057] To clearly illustrate the technical solution of this application, the terms "upper side" and "lower side" are defined in the accompanying drawings.

[0058] like Figure 1 A power tool according to one embodiment of this application is shown. 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 may also be other cutting tools, such as a table saw, miter saw, marble cutter, tile saw, chainsaw, etc.

[0059] In some embodiments, the power tool can also be a garden tool, such as a lawnmower, hair dryer, or a walk-behind power tool such as a lawnmower or washer. Alternatively, the power tool can be a decorating tool, such as a screwdriver / drill / wrench, hammer drill, nail gun, or sander. Alternatively, the power tool can be, for example, a reciprocating saw or a jigsaw. Alternatively, the power tool can be other benchtop tools, such as a wood milling machine. Alternatively, the power tool can be a sanding tool, such as an angle grinder or sander. Alternatively, the power tool can be other power tools, such as a fan. Alternatively, it can be a non-road-bound walking device, such as a multi-purpose vehicle, or an ATV, utility terrace vehicle (UTV), golf cart, or all-terrain vehicle (ATV), or an agricultural vehicle, such as a harvester or sprayer. Of course, it is understood that a walking device can also be a washer. It can also be an intelligent walking power tool that uses a motor or motor assembly to drive movement and perform work functions, such as an intelligent lawnmower.

[0060] It is understood that any power tool with a motor drive can adopt the technical solution disclosed in this embodiment, and the power equipment adopting the technical solution disclosed in this embodiment is within the scope of protection of this application. For example, the power tool can also be a power head, which includes a motor. The power head is used to adapt some output components to realize the function of the tool.

[0061] like Figure 1 As shown, circular saw 100 is used as an example. 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 in which the circular saw 100 is normally used. For example, the forward direction of the circular saw 100 is defined as front, and the direction opposite to the forward direction of the circular saw 100 is defined as back.

[0062] 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 for providing energy to the motor assembly 20. The battery pack 31, in conjunction with a corresponding power circuit, supplies power to the circular saw 100. Those skilled in the art should understand that the power supply is not limited to scenarios using DC power; it can also be powered by mains power or AC power, in conjunction with corresponding rectification, filtering, and voltage regulation circuits, to power corresponding components within the machine. In the following description, the battery pack 31 will be used instead of the power supply 31, but this should not be construed as a limitation of the present invention.

[0063] The battery pack 31 can be a lithium battery pack, a solid-state battery pack, or a pouch battery pack. In some embodiments, when the power supply includes multiple battery packs 31, the types of battery packs 31 can be the same or different. In some embodiments, the electrical parameters, structural parameters, and physical parameters of the multiple battery packs 31 can be the same or different.

[0064] like Figures 1 to 8 As shown, the circular saw 100 also includes: an output shaft 30, a main housing 11, a motor assembly 20, a power transmission mechanism 40, and a base plate 50. The output shaft 30 is used to mount a cutting element 61. The cutting element 61 rotates about the output shaft 301; in this embodiment, the cutting element 61 is a circular saw blade. The motor assembly 20 drives the output shaft 30 to rotate. The power transmission mechanism 40 transmits the output power of the motor assembly 20 to the output shaft 30. The main housing 11 houses the motor assembly 20 and the power transmission mechanism 40, and the output shaft 30 and the cutting element 61 are located outside the main housing 11. The base plate 50 is movably connected to the main housing 11, and the base plate 50 has a bottom surface 51 that contacts the workpiece. The base plate 50 has a saw blade through hole 54 extending along a first direction K1, through which the saw blade can protrude downwards from the bottom surface 51.

[0065] The main housing 11 includes a first housing 111, on which a gripping part 12 is formed or connected. The gripping part 12 is located at the rear end of the circular saw 100 and allows the user to hold it to operate the circular saw 100 for cutting. In some embodiments, the gripping part 12 is also provided with a control switch 81 and a safety switch 82. The control switch 81 is only triggered when the safety switch 82 is pressed. That is, the motor or motor assembly 20 can only be started after two actions. This avoids the danger of a single operation. When the user grips the gripping part 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 gripping part 13. The second gripping part 13 is located at the front end of the circular saw 100 and serves as an auxiliary handle. In one embodiment, the second gripping part 13 may also be an external handle mounted on the main housing 11; that is, the second gripping part 13 may be an auxiliary operating component separately mounted on the main housing 11.

[0066] The circular saw 100 also includes a guard assembly 60. The guard assembly 60 can at least partially surround the cutting element 61 to protect the environment and the user's safety. 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 housing 111. The movable guard 63 is fitted inside the fixed guard 62 and can rotate about the output axis 301 to fold into the fixed guard 62. The output shaft 30 extends into the fixed guard 62, and the cutting element 61 is detachably connected to the output shaft 30. In actual operation, different types of cutting elements 61 can be used depending on the material being cut. The cutting element 61 is set inside the fixed guard 62, with almost half of its outer circumference covered by the fixed guard 62, and the movable guard 63 rotates within the fixed guard 62 to cover or expose the lower half of the cutting element 61. The movable guard 63 is connected to the fixed guard 62 by an opening member 64 for the movable guard 63. When using the circular saw 100, the operator manually pushes the opening member 64 to rotate the movable guard 63 and expose part of the saw teeth.

[0067] The base plate 50 is movably connected to the fixed cover 62. In this embodiment, a connecting seat 52 is provided on the front side of the base plate 50, and the connecting seat 52 is connected to the fixed cover 62 by a pin 53, so that the fixed cover 62 can rotate relative to the base plate 50. The axis where 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 cover 62 rotates relative to the base plate 50 around the pivot axis 501, the relative position between the fixed cover 62 and the base plate 50 will change, resulting in different cutting depths of the circular saw 100. The rotation of the fixed cover 62 is achieved by applying force to the grip 12, causing the grip 12 to rotate relative to the base plate 50, thereby driving the fixed cover 62 to rotate relative to the base plate 50. It is understood that in some embodiments, the pivot axis 501 and the output axis 301 may intersect or be perpendicular.

[0068] like Figure 6 and Figure 8 As shown, 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... Figure 11 As shown, the stator 212 includes a stator core 2121 and a stator winding 2122. The rotor 214 includes a rotor core 2141 and a permanent magnet 2142. A drive shaft is formed or connected to the rotor 214 for outputting power. For an external rotor motor, the rotor is sleeved on the outside of the stator. For an internal rotor motor, the stator is sleeved on the outside of the rotor. In this embodiment, the overall structure of the motor is largely the same as that of a typical brushless motor, and will not be described in detail here.

[0069] The power transmission mechanism 40 is used 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 through 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 through the output shaft 30, and the torque is output outward through the output shaft 30. Taking the electric circular saw of this application as an example, the first motor 21 and the second motor 22 work together to drive the cutting piece 61 to perform cutting motion through the output shaft 30. Unlike multi-motor driven power tools in related technologies, such as outdoor walking equipment or wheeled equipment, where multiple motors, such as dual motors, are used to drive different output shafts or output parts respectively, for example, in related technologies, the first motor and the second motor are used to drive two or more drive wheels or drive shafts respectively. However, in this embodiment, the motor assembly including multiple motors drives the same output shaft, that is, the torque of the drive shafts of multiple motors is output through a single output shaft. The fact that the torque transmission paths of multiple motors end at the same point increases the overall efficiency range of the power tool, enabling even power tools with only one output shaft to be driven efficiently using multiple motors. Compared to multiple motors driving different output sections or output shafts, this application uses multiple motors to drive a single output shaft, which presents greater challenges in the transmission coordination, power distribution, and drive structure of the motor assembly 20 and the power transmission mechanism 40.

[0070] like Figures 4 to 10 As shown, the first motor 21 and the second motor 22 are arranged radially, meaning that the first drive shaft 211 and the second drive shaft 221 are arranged radially along the first drive shaft 211. Alternatively, the first drive shaft 211 and the second drive shaft 221 are arranged radially along 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 are intersecting or perpendicular.

[0071] The main housing 11 includes a receiving housing 14 for housing the motor assembly 20. The receiving housing 14 is formed or connected to the first housing 111. In this embodiment, the protective cover assembly 60 and the receiving housing 14 are substantially located on opposite sides of the first housing 111. It is understood that the protective cover assembly 60 is located on the left side of the first housing 111, and the receiving housing 14 is located on the right side of the first housing 111. In this embodiment, the first housing 111 and the receiving housing 14 are interconnected. A through hole 1111 is provided on the right side wall of the first housing 111 for the receiving housing 14 to pass through. The power transmission mechanism 40 is housed within the first housing 111 and located outside the receiving housing 14, thus making the arrangement of components within the main housing 11 more rational.

[0072] The housing 14 includes a first housing portion 141 for housing the first motor 21 and a second housing portion 142 for housing the second motor 22. For example... Figure 5 and Figure 8 As shown, when viewed by orthographic projection along the extension direction of the output shaft, the ratio of the outer dimension Lc of the projection of the housing 14 along the line connecting the projection of the first axis 201 and the projection of the second axis 202 to the outer circumference diameters D1 and D2 of any one of the motors is greater than or equal to 1.1. When the first motor 21 and the second motor 22 are used to control the output of the output shaft 30, if the first motor 21 and the second motor 22 are not arranged coaxially, the size of the housing 14 is greater than 1.1 times the diameter of a single motor to ensure that both the first motor 21 and the second motor 22 can be installed stably. This allows for a more stable installation of both the first motor 21 and the second motor 22 by arranging their relative positions appropriately. Furthermore, it allows users to easily distinguish between products controlled by a single motor and products controlled by both the first motor 21 and the second motor 22 simultaneously.

[0073] In this embodiment, taking the second motor 22 as an example, the second motor 22 is an internal rotor motor, and the "motor outer diameter" refers to the stator outer diameter of the motor. The outer diameter of the second motor 21 is D2. The ratio of the outer dimension Lc of the housing 14 along the line connecting the projection of the first axis 201 and the projection of the second axis 202 to the outer diameter D2 of the second motor 21 is greater than or equal to 1.2, 1.4, 1.6, and 1.8. In some embodiments, the ratio of the outer dimension Lc of the housing 14 along the line connecting the projection of the first axis 201 and the projection of the second axis 202 to the outer diameter D2 of the second motor 21 is greater than or equal to 2. In some embodiments, the ratio of the outer dimension Lc of the housing 14 along the line connecting the projection of the first axis 201 and the projection of the second axis 202 to the outer diameter D2 of the second motor 21 is greater than or equal to 2.1 and 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 separated, as in this embodiment, such as... Figure 6 and Figure 8 As shown, the first motor 21 and the second motor 22 do not overlap in the 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 extension direction of the cutting member 61, that is, there is no straight line extending along the output axis 301 that can pass through the first motor 21 and the second motor 22 simultaneously.

[0074] 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 is 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 dimensions of the motor assembly 20 more compact in the direction of the output axis 301. In this embodiment, the outer dimension Lc of the housing 14 along the line connecting the projection of the first axis 201 and the projection of the second axis 202 is greater than the outer dimension H1 of the housing 14 along the direction of the output axis 301, that is, the radial dimension of the housing 14 is greater than the axial dimension of the housing 14.

[0075] like Figure 6 and Figure 8As shown, the first receiving portion 141 supports at least a first bearing portion 215 of the first motor 21, which is a 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 receiving portion 141. The second receiving portion 142 supports at least a second bearing portion 225 of the second motor 22, which is a 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 receiving portion 142. This allows the first motor 21 and the second motor 22 to be stably mounted by the first receiving portion 141 and the second receiving portion 142, respectively.

[0076] In some alternative embodiments, the first motor 21 and the second motor 22 are arranged to partially overlap radially, that is, 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 makes the motor assembly 20 more compact in the radial direction. In this case, the outer dimension Lc of the housing 14 along the line connecting the projection of the first axis 201 and the projection of the second axis 202 can be less than or equal to the outer dimension H1 of the housing 14 along the output axis 301.

[0077] like Figures 7 to 10 As shown, 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 marking structure and the second marking structure are formed on or connected to the outer wall surface of the housing 14. This allows users to easily identify whether the product is driven by the first motor 21 and the second motor 22. By making the internal features of the product visible, the user's participation in product selection is increased.

[0078] In some embodiments, such as Figure 7As shown, the first marking structure 71a is configured to include a shape that approximates the outline of the first motor 21. The second marking structure 72a is configured to include a shape that approximates the outline of the second motor 22. For example, the first marking structure 71a is the first receiving portion 141 in the housing 14, and the outer wall of the first receiving portion 141 is an arc-shaped edge that approximates the shape of the first motor 21. The second marking structure 72a is the second receiving portion 142 in the housing 14, and the outer wall of the second receiving portion 142 is an arc-shaped edge that approximates the shape of the second motor 22. Alternatively, for example, the first marking structure 71a is the first receiving portion 141 in the housing 14, and the second marking structure 72a is the second receiving portion 142 in the housing 14. There is a distinct recess, protrusion, distinguishing shape, or dividing mark between the first receiving portion 141 and the second receiving portion 142, which divides the housing 14 into sections related to the number of motors. It is understandable that the outer wall of the first housing part 141 can be designed with other shapes from the perspective of industrial design, and the outer wall of the second housing part 142 can be designed with other shapes from the perspective of industrial design. However, in the eyes of the technical field and ordinary consumers, their shapes can be identified as motors and can be understood as shapes similar to the outline of motors. For example, in addition to circles that are the same as the shape of motors, there are ellipses, combinations of arcs and straight lines, shapes formed by multiple arcs, rectangles, polygons, triangles and other shapes.

[0079] In this embodiment, the outer walls of the first marker structure 71a and the second marker structure 72a are configured as continuous surfaces. For example... Figure 7 As shown, the outer walls of the first receiving section 141 and the second receiving section 142 are continuous structures, that is, the receiving shell 14 is an integral structure.

[0080] In some alternative embodiments, the first and second marker structures are configured as independent double-cylinder structures. The housing 14 can be a single integral structure, with the first and second marker structures being two closed structures disposed on the outer wall of the housing 14. Alternatively, the housing 14 can be a structure divided into two independent outer walls enclosing a first receiving portion 141 and a second receiving portion 142.

[0081] In some alternative embodiments, such as Figure 7As shown, the first marking structure 71b and the second marking structure 72b are additional line structures provided on the outer walls of the first receiving portion 141 and the second receiving portion 142. For example, the first marking structure 71b is a line structure on the outer wall of the first receiving portion 141 that resembles the outline of a motor. The second marking structure 72b is a line structure on the outer wall of the second receiving portion 142 that resembles the outline of a motor. The line structure can be a raised line, an embedded line, a recessed line, or a hollow line. For example, the first marking structure 71b is a line structure on the outer wall of the first receiving portion 141 that is associated with indicating a motor or the number of motors. The second marking structure 72b is a line structure on the outer wall of the second receiving portion 142 that is associated with indicating a motor or the number of motors, such as "words," "letters," "numbers," or similar, wherein "indicating a motor" is a line structure that can be identified as a motor by the technical field and the average consumer.

[0082] In some alternative embodiments, such as Figure 9 and Figure 10 As shown, the first marking structure includes first display units 71c and 71d, and the second marking structure includes second display units 72c and 72d. The first display units 71c and 71d, and the second marking structure including second display units 72c and 72d are respectively positioned in easily visible locations on the main housing 11. This allows the user to easily check the operating status of the first motor 21 and the second motor 22 simply by moving their line of sight while using the circular saw 100.

[0083] In some embodiments, such as Figure 9 As shown, the first display unit 71c includes a light-emitting element that at least indicates the on / off state of the first motor 21. For example, the first display unit 71c includes a light-emitting diode (LED), a COB (Chip On Board) LED, 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 portion of the upper surface of the first housing 111 near the housing 14. In some embodiments, the first display unit 71c is disposed on the upper surface of the housing 14. The first display unit 71c indicates the on / off state of the first motor 21 through changes in its display, such as through different indicative features like being lit and off, constantly lit and flashing, or different colors. The first display unit 71c can also be multiple lamps or light strips. The different display characteristics of different numbers or sections of lamps are used to indicate the speed range of the first motor 21. In some embodiments, the first display unit 71c can also indicate abnormalities as an alarm.

[0084] In some alternative embodiments, such as Figure 10As shown, the first display unit 71d includes a display screen, which serves as a human-machine 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) screen, or an organic light-emitting diode (OLED) display screen. The first display unit 71d is disposed on the upper surface of the housing 14. In some embodiments, the first display unit 71d is disposed on the upper surface of the first housing 111, and the first display unit 71d is disposed on the portion of the first housing 111 near the upper surface of the housing 14. Since the display screen serves as a human-machine interface, it displays more, more detailed, and more intuitive content. Therefore, depending on the settings, the display screen can display various information about the first motor 21 during its operation, such as power on / off information, speed information, output torque information, forward / reverse rotation information, loss information, temperature information, and even visually display the first motor 21 in a dynamic form on the display screen.

[0085] In some embodiments, the first display unit may include both a light-emitting element and a display screen. The second display unit 72c includes at least one of a light-emitting element or a display screen, used to indicate the operating status of the second motor 22. That is, the first display units 71c, 71d and the second display unit 72c may be of the same type of display component or of different types. For user convenience, the first display units 71c, 71d and the second display unit 72c are located in the same area, for example, both located on the upper part of the housing 14, one 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, they can be integrated, for example, using different brightness levels and colors of LEDs to indicate different motor start-up coordinations. For example, different display areas of the same display screen can be used to show information about the first motor 21 and the second motor 22, or different display screens can be used to show information about the first motor 21 and the second motor 22 respectively, or a menu can be used to allow the user to select whether to display information about the first motor 21, the second motor 22, or both.

[0086] 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. Both the first display portion 71e and the second display portion 72e are provided with an adhesive backing layer. That is, the first display portion 71e and the second display portion 72e are adhesive labels. The icon representing the first motor 21 and the icon representing the second motor 22 can be Chinese characters, English characters, graphics, etc. The first display portion 71e and the second display portion 72e can be disposed on the same adhesive-backed paper.

[0087] The technical solutions in the above embodiments can be used individually or in combination, thereby setting the specific implementation of the first mark structure and the second mark structure according to the actual needs of the power tool.

[0088] like Figure 6 and Figures 12 to 16 As shown, the power transmission mechanism 40 is used 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 through the output shaft 30. The power transmission mechanism 40 includes: a transmission assembly 41 disposed 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 disposed between the first motor 21 and the second motor 22, and the clutch assembly 42 is used to restrict 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, so that the first motor 21 and the second motor 22 can drive the output shaft 30 to operate in their respective high motor efficiency ranges. It is understood that the clutch assembly 42 is disposed between the first motor 21 and the second motor 22 in that, on the one hand, in 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. On the other hand, in terms of connection, the clutch assembly 42 has direct or indirect connection with the first motor 21 and the second motor 22, or direct or indirect power transmission path.

[0089] The transmission assembly 41 with speed reduction and torque extension enhances the cutting capability of the circular saw 100, resulting in high cutting efficiency. The coupling of the motor assembly 20 allows the circular saw 100 to be used in both light and high-load conditions. Simultaneously, it 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 lowers requirements for machine heat dissipation and other aspects.

[0090] The transmission assembly 41 is configured to connect at least one of the first drive shaft 211 and the second drive shaft 221 to the clutch assembly 42. For example... Figures 19 to 21 As shown, in one embodiment, the transmission assembly 41 includes a first gear set 41a for connecting the first drive shaft 211 and the output shaft 30. The transmission assembly 41 also includes a second gear set 41b for connecting the second drive shaft 221 and the output shaft 30, wherein a clutch assembly 42 is disposed between the second gear set 41b and the output shaft 30. In this embodiment, both the first gear set 41a and the second gear set 41b are reduction gear drives. The first gear set 41a is a single-stage reduction drive, meaning it provides one reduction motion. The second gear set 41b is also a single-stage reduction drive, meaning it provides one reduction motion. In some alternative embodiments, the first gear set 41a and the second gear set 41b may also include multi-stage reduction drives, or a speed-up drive followed by a speed-down drive. 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 one set of gears can provide multiple transmission ratios or reduction ratios. In this embodiment, the reduction ratio of the first gear set 41a is different from that of the second gear set 41b. The first gear set 41a and the second gear set 41b respectively include one or a combination of cylindrical gear transmission, bevel gear transmission, worm gear transmission, and planetary gear transmission.

[0091] 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 at one end of the first drive shaft 211 near the cutting member 61. The first driving gear 411 rotates about the first axis 201, and the first driven gear 412 meshes externally with the first driving gear 411. The first driven gear 412 is mounted on the output shaft 30 and rotates about the output axis 301. The first driving gear 411 and the first driven gear 412 form a reduction transmission. As one embodiment, the reduction ratio between the first driving gear 411 and the first driven gear 412 is 8 / 38.

[0092] 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 at one end of the second drive shaft 221 near the cutting member 61. The second driving gear 413 rotates about a second axis 202, and the second driven gear 414 meshes externally with the second driving gear 413. The second driven gear 414 is mounted on an idler shaft 415 and rotates about a third axis 401 of the idler shaft 415. The third axis 401 is parallel to but does not coincide with the first axis 201. The second driving gear 413 and the second driven gear 414 form a speed reduction transmission. 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 rotation of the first motor 21 and the second motor 22 in a first rotational direction, and to disengage the rotation of the first motor 21 and the second motor 22 in a second rotational direction. Optionally, the clutch assembly 42 is a one-way bearing or an overrunning clutch. A one-way transmission component 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 component 421 is connected to the idler shaft 415, and the outer ring is connected to a third gear 422. The third gear 422 meshes externally with the first driven gear 412 to couple the first motor 21 and 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 have essentially the same speed, 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. As one embodiment, the reduction ratio between the second driving gear 413 and the second driven gear 414 is 7 / 38.

[0093] During operation, when the first motor 21 starts working, it drives the output shaft 30 to rotate via the first gear set 41a. Due to the one-way transmission component 421, the output speed of the first motor 21 is limited to be transmitted to the second motor 22; that is, the one-way transmission component 421 only allows rotational transmission from the second drive shaft 221 (second driving wheel) of the second motor 22 to the second driven gear 414. At this time, only the first motor 21 drives the output shaft 30 to rotate. When the second motor 22 starts, the rotational lock of the one-way transmission component 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 can be understood that when the speed of the power output part of the one-way clutch (outer ring in this embodiment) is faster than that of the power source (inner ring in this embodiment), the one-way clutch is in a disengaged state, and there is no linkage between the inner and outer rings; that is, the one-way overrunning function of the one-way clutch. When the rotational speed of the second driven gear 414 is equal to or higher than the rotational speed of the first driven gear 412, that is, when the rotational speed of the second driven gear 414 is equal to or higher than the rotational speed of the third gear 422, the inner and outer rings of the one-way clutch are engaged, and the first motor 21 and the second motor 22 simultaneously drive the output shaft 30 to move. At the same time, 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 rotational speed of the second driven gear 414 (i.e., the idler shaft 415).

[0094] A non-thrust bearing 416 is provided at the first end of the idler shaft 415, and an elastic element 417 is provided at one end of the non-thrust bearing 416 to prevent the gears on the idler shaft 415 from moving.

[0095] In some embodiments, the clutch assembly also includes other mechanical clutch assemblies. For example, a jaw clutch, ratchet clutch, centrifugal clutch, differential, friction clutch, and hydraulic clutch; these mechanical clutches, in simple variations or combinations, can all be used as the clutch assembly of this application. Provided that the function of the clutch assembly of this application is fulfilled, the specific form of the structure does not affect the substantive content of this application.

[0096] In some embodiments, the clutch assembly further includes an electronic clutch. For example, an electromagnetic clutch. Examples include dry single-plate electromagnetic clutches, dry multi-plate electromagnetic clutches, wet multi-plate electromagnetic clutches, magnetic powder clutches, and slip-type electromagnetic clutches.

[0097] In some embodiments, the coupling of a mechanical clutch assembly and an electronic clutch can be used simultaneously to restrict or allow at least one drive output shaft 30 of the first drive shaft 211 or the second drive shaft 221 under preset conditions.

[0098] like Figure 15As shown, along 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 arrangement maximizes the position of the motor assembly above the output shaft, ensuring sufficient cutting depth for the circular saw. The output axis 301 is essentially the center of the cutting piece 61, and the cutting depth is closely related to the position of the output axis and the base plate. Positioning the drive axis of the motor assembly above the output axis does not affect the installation and use of the circular saw's base plate, and prevents interference with components near the base plate during the cutting process. 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 arrangement ensures a compact structure for the first and second motors and their transmission, as well as for the output shaft.

[0099] Optionally, the first motor 21 and the second motor 22 are radially arranged and staggered vertically. The output shaft 30 and the idler shaft 415 are located on opposite sides of the first drive shaft 211. The output shaft 30 and the idler shaft 415 are located on opposite sides 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.

[0100] like Figure 16 As shown, when the first motor 21e and the second motor 22e are arranged radially, they are substantially aligned vertically with the first drive shaft 211e and the second drive shaft 221e. The output shaft 30 and the idler shaft 415e are located on the same side of the first drive shaft 211e.

[0101] like Figure 17 As shown in one 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 equipped with a clutch assembly, meaning the first motor and the second motor have synchronous or substantially synchronous output torque. At this time, along 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. 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°.

[0102] like Figures 18-19As shown, in another embodiment of this 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 is mounted on the first drive shaft 211g. The first driving gear 411g meshes externally with the driven gear 412g on the output shaft 30g. The first driving gear 411g and the driven gear 412g are a speed reduction transmission.

[0103] The housing 14g is used to house the first motor 21g and the second motor 22g. Optionally, the first housing portion 141g for housing the first motor 21g and the second housing portion 142g for housing the second motor 22g are arranged axially. 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 1.1. When the first motor 21g and the second motor 22g are coaxially arranged, to ensure stable installation of both motors, the size of the housing 14g needs to be greater than 1.1 times the length of a single drive shaft. This allows for a more stable installation of both motors by arranging their relative positions. 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.

[0104] like Figure 19 As shown, both the first motor 21g and the second motor 22g are external rotor motors. The first motor 21g includes a first stator 212g and a first rotor 214g, with a first drive shaft 211g formed or connected to the first rotor 214g. The second motor 22g includes a second stator 222g and a second rotor 224g, with a second drive shaft 221g formed or connected to the second rotor 224g.

[0105] 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 implementations, the first drive shaft 211g and the second drive shaft 221g can be separate, independent shafts, connected by connectors or fasteners to achieve synchronous rotation. The system also includes a motor fixing part 24g for connection to the first stator 212g and the second stator 222g respectively. The motor fixing part 24g is provided with a receiving channel 241g, which is used to receive 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 and the second stator 222g along the first axis 201. The motor fixing part 24g coaxially connects the stator 212g of the first motor and the stator 222g of the second motor.

[0106] In some alternative embodiments, a clutch assembly is provided between the first motor shaft and the second motor shaft, or between the first motor and the output shaft, or 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 described in the above embodiments. The clutch assembly is disposed in the motor mounting portion, or between the first driving gear 411g and the first driven gear. In this case, 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.

[0107] In this application, a first motor 21 outputs a first torque and a first rotational speed. A second motor 22 outputs a second torque and a second rotational speed. In some embodiments, the first torque and the second torque are different. The first rotational speed and the second rotational speed are also different. It should be explained that the difference between the first torque and the second torque can be explained in several ways. In some embodiments, the first torque and the second torque can be different because the maximum output torques of the first motor 21 and the second motor 22 are different, but the output torques of the first motor 21 and the second motor 22 may be the same at a certain moment or within a certain time period during their operation. In some embodiments, the first rotational speed and the second rotational speed can be different because the maximum output rotational speeds of the first motor 21 and the second motor 22 are different, but the output rotational speeds of the first motor 21 and the second motor 22 may be the same at a certain moment or within a certain time period during their operation. In some embodiments, the output rotational speed ranges of the first motor 21 and the second motor 22 may be different because the output rotational speeds of the first motor 21 and the second motor 22 may be the same at a certain moment or within a certain time period during their operation.

[0108] In some embodiments, the first motor 21 and the second motor 22 are, as one example, a low-output torque motor and a high-output torque motor. Alternatively, the first motor 21 can be a high-output torque motor and the second motor 22 a low-output torque motor. Or, the first motor 21 and the second motor 22 can be the same type of motor, but with different output speeds and output torques. In this embodiment, both the first motor 21 and the second motor 22 are brushless DC motors.

[0109] Meanwhile, the first motor 21 and the second motor 22 also include at least one different structural parameter. The structural parameters include the motor's outer diameter D and the motor stack length. Here, it should be explained that "motor outer diameter" refers to the overall outer diameter of the motor. "Motor stack length" refers to the length of the stator core. In this embodiment, the motor diameter of the first motor 21 is less than or equal to 75mm. The motor diameter of the first motor 21 is less than or equal to 70mm. The motor diameter of the first motor 21 is less than or equal to 65mm. In some embodiments, the motor diameter of the first motor 21 is less than or equal to 69mm, 68mm, 67mm, 66mm, 64mm, 63mm, 62mm, 61mm, 60mm, 59mm, 58mm, 57mm, 56mm, or 55mm. In this embodiment, the motor diameter of the second motor 22 is less than or equal to 75mm. The motor diameter of the second motor 22 is less than or equal to 70mm. The motor diameter of the second motor 22 is less than or equal to 65mm. In some embodiments, the motor diameter of the second motor 22 is less than or equal to 69mm, 68mm, 67mm, 66mm, 64mm, 63mm, 62mm, 61mm, 60mm, 59mm, 58mm, 57mm, 56mm, or 55mm.

[0110] In some embodiments, the structural parameters of the first motor 21 and the second motor 22 include the stator core outer diameter, stator core inner diameter, rotor core outer diameter, rotor core inner diameter, rotor magnetic pole thickness, stator magnetic pole thickness, air gap length, core length, number of stator pole pairs, corresponding radian of stator magnetic poles, number of rotor pole pairs, and corresponding radian of rotor magnetic poles. At least one structural parameter differs between the first motor 21 and the second motor 22.

[0111] Of course, in some embodiments, the first motor 21 and the second motor 22 can be two completely identical motors. A higher efficiency range can be achieved through mutual coupling.

[0112] In this embodiment, the battery pack 31 supplies power to the first motor 21 and the second motor 22. The battery pack 31, in conjunction with a corresponding power circuit, supplies power to the first motor 21 and the second motor 22. Figure 5 and Figure 7 As shown, a semi-open battery compartment 15, recessed inwards, is provided on the main housing 11. The battery compartment 15 is located between the grip portion 12 and the motor assembly 20. The battery compartment 15 and the motor assembly 20 are located on the same side of the first housing 111. The battery compartment 15 and the battery pack 31 are located in front of the grip portion 12. The battery compartment 15 is located on the first housing 111.

[0113] like Figure 20As shown, the battery compartment 15 includes a connecting portion 1511 electrically connected to the battery pack 31, and a tool terminal (not shown) is provided on the connecting portion 1511. The tool terminals (not shown) with the same structure are provided on different power tools. The battery pack 31 includes an insertion structure and a terminal interface. The tool terminal is adapted to the terminal interface on the battery pack 31. The tool terminals with the same structure are provided on different power tools so that the battery pack 31 can power a variety of different power tools. The power circuit corresponding to this is adjusted according to 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 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 located on the same side of the cutting member 61, and after the battery pack 31 is inserted into the battery compartment 15, at least partially after the first motor and the second motor are positioned, and at least partially 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.

[0114] like Figure 20 As shown, the circular saw 100 also includes a controller 17 for controlling the motor assembly 20. The controller 17 is mounted on a control circuit board 18, which includes a PCB (Printed Circuit Board) and an FPC (Flexible Printed Circuit Board). The controller 17 uses a dedicated control chip, such as a microcontroller or a microcontroller unit (MCU). It should be noted that the control chip can be integrated into the controller 17 or can be set independently of the controller 17. The structural relationship between the drive chip and the controller 17 is not limited in this embodiment.

[0115] like Figure 6 and Figure 8 As shown, the motor assembly 20 also includes: a first fan 216 supported by a first drive shaft 211, the first fan 216 being driven by a first motor 21 to rotate and generate cooling airflow; and a second fan 226 supported by a second drive shaft 221, the second fan 226 being driven by a second motor 22 to rotate and generate cooling airflow. Figures 21 to 22As shown, air vents are formed on the main housing 11. When either the first fan 216 or the second fan 226 rotates, a cooling airflow is generated. This cooling airflow passes through at least the control circuit board and then through at least one motor in the motor assembly. Brushless motors have higher output power than brushed motors. However, the heat dissipated by the brushless motor itself also increases; furthermore, the heat dissipated by the control circuit board 18, which controls the power supply to the motor, also increases. Therefore, sufficient heat dissipation of the control circuit board 18 is required. In some embodiments, when the first motor and the second motor are coaxially arranged, only the first fan may be supported by at least one of the first drive shaft, the second drive shaft, or the output shaft. When either the first motor or the second motor rotates, the first fan rotates and generates a cooling airflow.

[0116] The airflow outlet includes a first air inlet 161 and a first air outlet 162. Cooling airflow enters the main housing 11 through the first air inlet 161 and exits the main housing 11 through the first air outlet 162. A control circuit board 18 is disposed within the first housing 111. The first air inlet 161 allows cooling airflow to enter the receiving housing 14 from the first housing 111. When any motor in the motor assembly 20 is started, the corresponding fan rotates synchronously to generate cooling airflow. This ensures that the cooling airflow passes 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 in the cooling airflow path. Thus, when any motor in the motor assembly 20 is started and the fan rotates, external air can flow into the interior of the circular saw 100 through the air inlet, forming a cooling airflow; and, in its flow towards the fan, the cooling airflow passes through at least the circuit board and any one of the motors in the motor assembly 20, and finally exits through the air outlet.

[0117] like Figures 20 to 22The diagram shows a first embodiment of the heat dissipation scheme. A control circuit board 18 is disposed above the motor assembly 20. The plane extending from the control circuit board 18 is defined as the second plane S2. The plane containing the bottom surface 51 of the base plate 50 is defined as the third plane S3. Along the direction perpendicular to the extension of the cutting member 61, i.e., along the output axis, the second plane S2 and the third plane S3 are both straight lines. 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 a heat-dissipating material, and the heat sink 191 is disposed on the sidewall in contact with the control circuit board 18. The heat sink 191 includes heat dissipation fins 192 extending a certain length. The control circuit board 18 is connected to the heat sink 191 and can transfer the heat emitted by the control circuit board 18, conducting the heat from the control circuit board 18 to the heat sink 191 and the heat dissipation fins 192. In this embodiment, the plane containing 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 the adjacent fins will be in the direction of the cooling airflow.

[0118] A first fan 216 is disposed at one 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. A second fan 226 is disposed at one 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. A circuit board housing 19 and a control circuit board 18 are disposed radially outside the first fan 216 and the second fan 226. Optionally, the circuit board housing 19 and the control circuit board 18 are disposed radially above the first fan 216 and the second fan 226. The circuit board housing 19 and the control circuit board 18 are disposed within the first housing 111. A 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 sidewall and the upper sidewall of the first housing 111. It is understood that a portion of the first air inlet 161 is located on the upper sidewall, and a portion is located on the sidewall of the first housing 111 away from the output shaft 30, so that the heat dissipation airflow path can have a longer contact path with the circuit board housing 19. That is to say, the first air inlet 161 and the fan are basically located on the upper and lower sides of the control circuit board 18, and on the left and right sides. The first air inlet 161 is configured as a matrix of holes formed by multiple through holes to prevent the operator from accidentally inserting fingers or other objects into the airflow port.

[0119] Since the first fan 216 and the second fan 226 are basically 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 specifically determined according to 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 not be provided. This ensures that cooling airflow flowing through the control circuit board 18 from the first air inlet 161 is generated by effectively utilizing the negative pressure generated by the rotation of the fans.

[0120] The airflow outlet also includes a first air outlet 162 that allows the cooling airflow to exit the main housing 11. The first air outlet 162 connects the housing 14 and the first housing 111 with the external environment. In this embodiment, the airflow direction of the first air outlet 162 is towards 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, an airflow guide rib is provided inside the first housing 111 to guide the cooling airflow so that it flows within the space defined by the airflow guide rib.

[0121] During the cutting operation, with the bottom surface 51 of the base plate abutting the workpiece to be cut, the control switch 81 is triggered normally, at least the first motor 21 starts, and the saw blade rotates to cut the workpiece. At the same time, at least the first fan 216 rotates to create negative pressure, driving external air into the interior of the circular saw 100 for heat dissipation. After the fan rotates, the cooling airflow enters the interior of the first housing 111 through the first air inlet 161, first flows through the circuit board housing 19 and the control circuit board 18, and then flows through the first connecting port 146 through the first motor 21 and the second motor 22, exiting through the first air outlet 162.

[0122] In this embodiment, a second air outlet 163 is also included. The 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 the air outlet 163 blows air away from the cutting workpiece 61. Therefore, the airflow from the second air outlet 163 has both a heat dissipation function and a dust blowing function, which can blow away the dust generated during the cutting process. Optionally, the second air outlet 163 includes a third connecting port 164 for connecting the housing 14, the first housing 111 and the outside, and a fourth connecting port 165 is provided on the side wall of the base plate 50 for the 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 such 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 mostly flows out from the first air outlet 162. The second heat dissipation air path F2 is configured such that when at least one of the first motor 21 and the second motor 22 is running, 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 second air outlet 163.

[0123] 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. Multiple controllers can also be mounted 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 via communication or electrical connections.

[0124] like Figure 23 As shown, in one optional embodiment, there are two circuit board housings 19 and at least two control circuit boards 18. Using multiple control circuit boards 18 to configure multiple controllers can reduce the capability requirements of the control circuit boards 18. The circuit board housings 19 are all placed radially outside the first and second fans. Optionally, the circuit board housings 19 and the control circuit boards 18 are positioned radially above the first and second fans 226. The circuit board housings 19 include 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 identical to increase versatility. Alternatively, they can be different, with specific structures for the first circuit board housing 19a and the second circuit board housing 19b depending on their specific locations.

[0125] like Figure 24As shown, in an optional embodiment, the second plane S2 and the third plane S3 of the circuit board 18 are spatially perpendicular. Optionally, along the extension direction perpendicular to 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 cover. In this embodiment, the circuit board housing 19 is in close contact with the fixed cover, so that the heat of the circuit board housing 19 can be dissipated through radiation from the surface of the fixed cover, increasing the heat dissipation path of the control circuit board 18.

[0126] like Figure 25 The diagram shows a second embodiment of the heat dissipation solution. A 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 located between the storage housing and the battery compartment 15. Along the direction perpendicular to the cutting member 61, the second plane S2 is a straight line, and the third plane S3 is a straight line; the second plane S2 intersects or is perpendicular to the third plane S3.

[0127] The structure of the motor assembly is the same as in the first embodiment of the heat dissipation scheme. The circuit board housing 19 and the control circuit board 18 are disposed radially outside the first fan 216 and the second fan 226. Optionally, the circuit board housing 19 and the control circuit board 18 are disposed radially behind the first fan 216 and the second fan 226, between the battery housing 15 and the housing housing 14. A second air inlet 166 is disposed in the battery housing 15. In this embodiment, as... Figure 7 As shown, the battery compartment 15 includes a first outlet 151 for entering and exiting at least one battery pack 31, and a second outlet 152 different from the first outlet 151. Figure 7 and Figure 25 As shown, the second air inlet 166 includes a first outlet 151, a second outlet 152, and a fifth connecting port 167 connecting the battery housing 15 and the first housing 111. It can be understood that the fifth connecting port 167 is an airflow port for allowing cooling airflow to exit the battery housing 15. To ensure more efficient cooling, the fifth connecting port 167 is positioned above the first fan 216 and the second fan 226, and at least below the first outlet 151.

[0128] like Figure 7As shown, since the first fan 216 and the second fan 226 are basically 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 specifically determined according to 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 not be provided. This ensures that by effectively utilizing the negative pressure generated by the rotation of the fans, a cooling airflow flowing through the battery pack 31 and the control circuit board 18 is generated from the second air inlet 166.

[0129] like Figure 7 and Figure 25 As shown, the airflow port also includes a first air outlet 162 that allows the cooling airflow to exit the main housing 11. The first air outlet 162 connects the housing 14 and the first housing 111 with the external environment. In this embodiment, the airflow direction of the first air outlet 162 is towards 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, an airflow guide rib is provided inside the first housing 111 to guide the cooling airflow so that the cooling airflow flows within the space defined by the airflow guide rib.

[0130] During the cutting operation, with the bottom surface 51 of the base plate abutting the workpiece to be cut, the control switch 81 is triggered normally, at least the first motor 21 starts, and the saw blade rotates to cut the workpiece. At the same time, at least the first fan 216 rotates to create negative pressure, driving external air into the interior of the circular saw 100 for heat dissipation. After the fan rotates, the cooling airflow enters the battery compartment 15 and the interior of the first housing 111 from 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 connecting port 146, the first motor 21 and the second motor 22, and exits from the first air outlet 162.

[0131] In this embodiment, a second air outlet 163 is also included. The 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 the air outlet 163 blows air away from the saw blade. Therefore, the airflow from the second air outlet 163 not only has a heat dissipation function but also a dust blowing function, which can blow away the dust generated during the cutting process. Optionally, the second air outlet 163 includes a third connecting port 164 for connecting the housing 14, the first housing 111, and the outside, and a fourth connecting port 165 is provided on the side wall of the base plate 50 for additional dust blowing function. Figure 25As shown, the airflow path includes a first cooling airflow path F1 and a second cooling airflow path F2. The first cooling airflow path F1 is configured such that when at least one of the first motor 21 and the second motor 22 is running, the cooling airflow enters through the second air inlet 166, flows through the battery pack 31, the control circuit board 18, and the motor assembly 20, and then mostly flows out through the first air outlet 162. The second cooling airflow path F2 is configured such that when at least one of the first motor 21 and the second motor 22 is running, the cooling airflow enters through the second air inlet 166, flows through the battery pack 31, the control circuit board 18, and the motor assembly 20, and then mostly flows out through the second air outlet 163.

[0132] In some embodiments, the circular saw 100 is provided with both a first air inlet 161 and a second air inlet 166 to ensure more efficient heat dissipation for the control circuit board 18 and the motor assembly 20.

[0133] 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. Multiple controllers can also be mounted 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 via communication or electrical connections.

[0134] like Figure 26 As shown, in one optional embodiment, there are two circuit board housings 19 and at least two control circuit boards 18. Using multiple control circuit boards 18 to configure multiple controllers can reduce the capability requirements of the control circuit boards 18. The circuit board housings 19 and control circuit boards 18 are disposed radially outside the first fan 216 and the second fan 226. Optionally, the circuit board housings 19 and control circuit boards 18 are disposed radially behind the first fan 216 and the second fan 226, between the battery compartment 15 and the 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 identical to increase versatility. They can also be different, with specific structures for the first circuit board housing 19a and the second circuit board housing 19b depending on their specific locations.

[0135] like Figures 1 to 5 As shown, the cutting element 61 in this embodiment is a circular saw blade 100 with an outer diameter greater than 6 inches. In some embodiments, the circular saw blade 100 has an outer diameter ranging from approximately 6 inches to 12 inches. Figure 2 and Figure 3 As shown, along the direction perpendicular to the cutting element 61, the projection of the centroid G of the circular saw 100 is located between the rear edge of the base plate 50 and the output axis 301. Optionally, as... Figure 2As shown, this is the first state of the circular saw 100, in which the fixed guard 62 is rotated to its 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 onto the output axis 301 and the distance L2 between the rear edge of the base plate 50 and 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 onto the output axis 301 and 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 is always located on the rear side of the output axis 301, that is, on the side of the output axis 301 closer to the grip 12. Figure 3 As shown, this is the second state of the circular saw 100. At this time, when the fixed guard 62 rotates to the maximum angle relative to the base plate 50 about the pivot axis 501, the distance L1' from the center of gravity of the circular saw 100 to the output axis 301 is the minimum.

[0136] like Figure 4As shown, the cutting element 61 extends within a cutting plane S4, and the gripping portion 12 is substantially symmetrically arranged about the first plane S1. In the direction perpendicular to the bottom surface 51 of the base plate, the projections of the first drive shaft 201 and the second drive shaft 202 have two endpoints furthest apart in the direction of the output axis 301. A width interval W is defined between two straight lines on the projection plane, each passing through one endpoint and perpendicular to the output axis 301. The projection of the circular saw's center of gravity G is located within this 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 arranged parallel to each other. In the 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 furthest 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 single unit. The width interval W is defined between the straight line passing through the first endpoint and perpendicular to the output axis and the straight line passing through the second endpoint and perpendicular to the output axis. That is, the width interval W is the overall position range of the machine within this width. In the front-back direction of the circular saw, the width interval is not limited to the front-back range of the motor assembly, but rather the front-back range of the entire circular saw. In one embodiment, when the first motor and the second motor are arranged radially and the first drive shaft and the second drive shaft intersect, the projections of the first drive shaft and the second drive shaft in the 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 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. The width interval W is defined between the straight line passing through the first endpoint and perpendicular to the output axis and the straight line passing through the second endpoint and perpendicular to the output axis. That is, the width interval W is the overall position range of the machine within this width. In the front-back direction of the circular saw, the width interval is not limited to the front-back range of the motor assembly, but rather the front-back range of the entire circular saw.

[0137] In one embodiment, when the first motor and the second motor are arranged coaxially, the projections of the first drive shaft and the second drive shaft in the 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 drive shaft and the second drive shaft are arranged left-right in the left-right direction of the circular saw; therefore, the first endpoint is the leftmost end, and the second endpoint is the rightmost end. A width range W is defined between a straight line passing through the first endpoint and perpendicular to the output axis and a straight line passing through the second endpoint and perpendicular to the output axis. That is, the width range W is the position range of the entire machine within this width. The width range in the front-back direction of the circular saw is not only the front-back range of the motor assembly, but also the front-back range of the entire circular saw. This prevents poor handling of the circular saw 100 during operation, ensuring that the center of gravity of the circular saw is set within the width range of the first motor and the second motor in the width direction, making the force application of the entire machine more stable during operation.

[0138] In some embodiments, along a direction perpendicular to the bottom surface 51 of the base plate, the projection of the center of gravity G of the circular saw 100 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 cutting plane S4 on the left. Simultaneously, 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 between the cutting plane S4 and 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 positioned as close as possible to the first plane S1 to avoid causing unpleasant operating feel during operation. Optionally, the center of gravity G of the circular saw 100 can be located to the left or right of the first plane S1.

[0139] The base plate 50 has a hole extending along the first direction K1 to allow the cutting piece 61 to pass through the base plate 50. For example... Figure 5 As shown, along the first direction K1, the ratio of the outer edge dimension L3 of the housing 14 to the outer edge dimension La of the main housing 11 is greater than or equal to 0.2 and less than or equal to 0.4. It can be understood that in some embodiments, the outer edge dimension L3 of the housing 14 may be the same as the outer side dimension Lc of the housing 14 along the perpendicular direction of the first drive shaft 211 and the second drive shaft 221.

[0140] like Figure 4 and Figure 8 As shown, along the output axis 301, the ratio of the outer edge dimension H1 of the 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.

[0141] like Figure 27 As shown, controller 17 is used to control motor assembly 20. Controller 17 is configured to determine the start-up state of the first motor 21 and the second motor 22 according to preset conditions.

[0142] In one embodiment, the controller includes a first controller 171 and a second controller 172, i.e., 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) 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) drive module. A battery pack 31 supplies power to both the first controller 171 and the second controller 172. The first controller 171 is connected to the first motor 21, and the second controller 172 is connected to the second motor 22. It is understood that the first controller 171 and the second controller 172 are connected via serial communication, but they also have relatively independent control modules.

[0143] The first controller 171 acquires 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 and operation of the first motor 21 through PWM signals. The second controller 172 acquires 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 and operation of the second motor 22 through PWM signals. This is equivalent to having two independent control circuits controlling the first motor 21 and the second motor 22. The electrical characteristic parameters may also include parameters such as bus current, current storage time, and demagnetization time.

[0144] In this embodiment, the first motor 21 and the second motor 22 are both three-phase brushless motors. They include electronically commutated three-phase stator windings U, V, and W. In some embodiments, the three-phase stator windings U, V, and W are connected in a star configuration; in other embodiments, they are connected in a delta configuration. However, it must be understood that other types of brushless motors are also within the scope of this disclosure. A brushless motor may include fewer or more than three phases. A drive circuit is electrically connected to the stator windings U, V, and W of the motor to transfer current from the battery pack 31 to the stator windings U, V, and W to drive the motor to rotate.

[0145] like Figure 29 As shown, the specific control flow is as follows:

[0146] S210: Control switch 81 is activated.

[0147] During operation, the first controller 171 detects that the control switch 81 is activated, that is, it receives a start signal.

[0148] S220: The first motor meets the starting conditions. If yes, proceed to S240; otherwise, proceed to S230.

[0149] S230: The first motor does not start, and the second motor does not start.

[0150] S240: The first motor starts, but the second motor does not start.

[0151] The first controller 171 controls the first motor 21 to start with a first preset step size.

[0152] S250: The operation of the first motor meets the preset conditions, such as the speed being greater than the first preset speed. If yes, proceed to S260; otherwise, proceed to S240.

[0153] S260: Send the second motor start signal.

[0154] S270: The second motor meets the starting conditions. If yes, proceed to S290; otherwise, proceed to S280.

[0155] S280: The first motor starts, but the second motor does not start.

[0156] S290: The first motor starts, the second motor starts, and they run under preset conditions, such as running at full duty cycle respectively.

[0157] The first controller 171 sends a signal to the second controller controlling the second motor 22, causing the second controller to start the second motor 22. The second controller 172 controls the second motor 22 to start with a second preset step size. This second preset step size is greater than or equal to the first preset step size, to shorten the start-up time of both motors. In this embodiment, after the first motor 21 has stabilized, it operates at full duty cycle. After the second motor 22 has stabilized, both the first motor 21 and the second motor 22 operate at full duty cycle. It is understood that changes in motor speed can be obtained through modulation and calculation of motor electrical characteristic parameters, such as phase current. Full duty cycle does not necessarily refer to 100%; it refers to the maximum duty cycle specified in the product performance specifications, and can be 90%, 80%, etc.

[0158] S300: The control switch is released, S230 is executed, the first motor does not start, and the second motor does not start.

[0159] As one example, such as Figure 28As shown, 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 the two control circuit boards 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 173a and a second drive circuit 173b, wherein the first drive circuit 173a is connected to the first controller 171 and the battery pack 31. The second drive circuit 173b is connected to the second controller 172 and the battery pack 31. That is, the battery pack 31 is connected to the drive circuit, and supplies power to the controller through the drive circuit.

[0160] In this embodiment, the first motor 21 and the second motor 22 are both three-phase brushless motors. They include electronically commutated three-phase stator windings U, V, and W. In some embodiments, the three-phase stator windings U, V, and W are connected in a star configuration; in other embodiments, they are connected in a delta configuration. However, it must be understood that other types of brushless motors are also within the scope of this disclosure. Brushless motors may include fewer or more than three phases.

[0161] 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 used to transfer the 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 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 and change their respective conduction states, thereby changing the current loaded by the battery pack 31 on 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., FET, BJT, IGBT, etc.). In some embodiments, the drive circuit 173a may also include more than six controllable semiconductor power devices. It is understood that the aforementioned switching element can also be any other type of solid-state switch, such as an insulated gate bipolar transistor (IGBT), a bipolar junction transistor (BJT), etc.

[0162] The controller specifically controls the on / off state of the switching elements in the drive circuit through a control chip. In some embodiments, the controller controls the ratio between the on and off times 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.

[0163] The first controller 171 further includes a first ADC drive module, which acquires electrical characteristic parameters such as phase current and bus voltage. The second controller 172 further includes a second ADC drive module, which acquires electrical characteristic parameters such as phase current and bus voltage through the first ADC drive module.

[0164] 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 through the first ADC drive module and sends the detected parameters as a signal to its first PWM drive control module. The first PWM drive control module then sends a PWM control signal to the first drive circuit 173a, controlling the ratio between the on-time and off-time of the drive switch based on the PWM control signal. Similarly, the second controller 172 detects preset parameters through the second ADC drive module and sends the detected parameters as a signal to its second PWM drive control module. The first PWM drive control module then sends a PWM control signal to the second drive circuit 173b, controlling 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, and demagnetization time. 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.

[0165] like Figure 30 As shown, the specific control flow is as follows:

[0166] S411: Control switch 81 is activated.

[0167] During operation, the first controller 171 detects that the control switch 81 is activated, that is, it receives a start signal.

[0168] S412: The first motor meets the starting conditions. If yes, execute S141; otherwise, execute S413.

[0169] S413: The first motor does not start, and the second motor does not start.

[0170] S414: The first motor starts, but the second motor does not start.

[0171] The first controller 171 controls the first motor 21 to start.

[0172] S415: The operation of the first motor meets the first preset condition, such as the speed being greater than the first preset speed. If yes, then execute S414; otherwise, execute S416 and S417.

[0173] Taking rotational speed as an example, the first controller 171 first determines the relationship between the rotational speed of the first motor 21 and a first rotational speed threshold. If the rotational speed of the first motor 21 is higher than the first rotational speed threshold, the first motor 21 maintains its current operating state to drive the output shaft 30, and the second motor 22 does not need to be started. Optionally, the first rotational speed threshold is 5000 RPM.

[0174] S416: The second motor starts and operates under the second preset conditions.

[0175] Optionally, the second motor 22 enters a hot standby state, meaning the second motor starts and remains ready to operate under the second preset conditions. Optionally, still taking speed as an example, the second preset speed is less than the first speed threshold, and the second preset speed is the optimal output efficiency speed of the second motor. Optionally, the second preset speed is 4500 RPM.

[0176] S417: The operation of the first motor meets the second preset condition, such as the speed being greater than the second preset speed. If yes, then execute S415; otherwise, execute S418.

[0177] S418: The second motor operates under the third preset condition, and the first motor operates under the second preset condition.

[0178] When the speed of the first motor 21 is less than the second preset speed, the second motor 22 is started to operate under 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 its maximum duty cycle after startup. The first motor operates at a constant speed of the second preset speed. That is to say, at this time, both the first motor 21 and the second motor 22 begin to drive the output shaft, thus entering dual-motor mode.

[0179] S419: The operation of the first motor meets the fourth preset condition, such as the speed being less than the fourth preset speed. If yes, then execute S420; otherwise, execute S418.

[0180] During operation, the rotational speed of the first motor is continuously monitored. When the operation of the first motor 21 meets the fourth preset condition, optionally, if the rotational speed is not less than the fourth preset speed, it is determined that the output torque of the motor assembly can meet the required torque of the current output shaft. Optionally, the fourth preset speed is less than the second preset speed, for example, the fourth preset speed is 3500 RPM.

[0181] S420: The first motor, i.e., the second motor, operates at full duty cycle.

[0182] When the rotational speed is less than the fourth preset 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.

[0183] To avoid frequent switching between single and dual motor modes, in actual applications, if the speed is higher than 5000 RPM and the current is lower than the current threshold in dual motor mode, it will switch to single motor operation only after a preset time.

[0184] S421: The control switch is released, S413 is executed, the first motor does not start, and the second motor does not start.

[0185] The foregoing has shown and described 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 way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this application.

Claims

1. A power tool, comprising, an output shaft for outputting torque; the output shaft rotates around the output shaft line; a first motor comprising a first driving shaft rotating around a first axis; a second motor comprising a second driving shaft rotating around 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, torque of the first driving shaft and the second driving shaft being outputted 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 speed reduction mechanism, the speed reduction mechanism providing at least one speed reduction ratio; the transmission assembly comprises a first gear assembly connecting the first motor and the output shaft, the first gear assembly providing at least one speed reduction ratio; the transmission assembly comprises a second gear assembly connecting the second motor and the output shaft, the second gear assembly providing at least one speed reduction ratio; a clutch assembly arranged between the first motor and the second motor, the clutch assembly connecting the second gear assembly and the output shaft; the clutch assembly is used to limit or allow at least one of the first driving shaft or the second driving shaft to drive the output shaft under a preset condition.

2. The power tool of claim 1, wherein, the transmission assembly is configured to connect at least one of the first driving shaft and the second driving shaft with the clutch assembly.

3. The power tool of claim 1, wherein, the clutch assembly comprises a one-way transmission member, the one-way transmission member being operable to connect the first motor and the second motor in rotation in a first rotation direction, and the one-way transmission member being operable to separate the first motor and the second motor in rotation in a second rotation direction.

4. The power tool of claim 1, wherein, the clutch assembly comprises a third gear, the first gear assembly comprises a first driven gear, the third gear is engaged with the first driven gear, and a transmission ratio of the third gear and the first driven gear is substantially 1.

5. The power tool of claim 1, wherein, the clutch assembly comprises an idler shaft rotating around a clutch axis, the second gear assembly comprises a second driven gear arranged on the idler shaft, and when a rotation speed of the idler shaft is greater than a rotation speed of the output shaft, the clutch assembly drives the output shaft to rotate at the rotation speed of the idler shaft.

6. The power tool of claim 5, wherein, a first end of the idler shaft is provided with a non-thrust bearing, and one end of the non-thrust bearing is provided with an elastic member.

7. The power tool of claim 1, wherein, at least one of the first gear assembly and the second gear assembly comprises a helical gear.

8. The power tool according to claim 1, wherein, when viewed in orthographic projection along an extension direction of the output shaft, a projection of the first axis and a projection of the second axis are located above a projection of the output shaft line.

9. The power tool of claim 8, wherein, when viewed in orthographic projection along an extension direction of the output shaft line, an included angle a between a line connecting the first axis and the output shaft line and a line connecting the second axis and the output shaft line is greater than or equal to 45° and less than or equal to 180°.

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