Electric tool

Abstract

The utility model discloses an electric tool. The electric tool comprises a shell; the energy storage device is configured to supply power to the electric tool; the motor is arranged in the shell and comprises a stator assembly and a rotor assembly; the driving board is provided with a plurality of semiconductor switches, and a driving circuit formed by the plurality of semiconductor switches is electrically connected with the energy storage device; a controller configured to control on-off of the plurality of semiconductor switches to regulate power supply from the energy storage device to the motor; the semiconductor switches are packaged in a surface mounting mode, and the length and the width of each semiconductor switch are both larger than or equal to 9 mm. By the adoption of the technical scheme, the electric tool with the semiconductor switch good in current resistance and voltage resistance can be provided.

Description

Technical Field

[0001] The present application relates to the technical field of tools, and in particular to an electric tool. Background Art

[0002] Compared with engine-type tools, electric tools are more environmentally friendly and thus widely used. Electric tools generally use motors to drive work. The electric tools are provided with a circuit board for controlling the motor, on which a plurality of semiconductor switches are provided, and the motor is electrically connected to the circuit board through a motor line.

[0003] In the related art, a plurality of semiconductor switches need to be packaged. Currently, each semiconductor switch usually uses two or more MOS tubes connected in parallel and is packaged.

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

[0005] One object of the present application is to solve or at least alleviate part or all of the above problems. To this end, one object of the present application is to provide an electric tool with a semiconductor switch having good current and voltage resistance performance.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] An electric tool comprises: a housing; an energy storage device configured to supply power to the electric tool; a motor disposed in the housing and comprising a stator assembly and a rotor assembly; a drive board provided with a plurality of semiconductor switches, wherein a drive circuit formed by the plurality of semiconductor switches is electrically connected to the energy storage device; a controller configured to control the on and off of the plurality of semiconductor switches to regulate the power supply from the energy storage device to the motor; the semiconductor switches are surface mounted in a package, wherein the length and width of a single semiconductor switch are both greater than or equal to 9 mm.

[0008] In some embodiments, the driving board includes a circuit layer, an insulating layer, and a metal base layer.

[0009] In some embodiments, the material of the metal base layer is aluminum.

[0010] In some embodiments, the drive plate has a size greater than or equal to 65 square centimeters.

[0011] In some embodiments, the semiconductor switch has a source, a drain, and a gate, wherein the source has 7 pins.

[0012] In some embodiments, the power tool is a wheeled garden tool.

[0013] In some embodiments, the power tool is a push mower.

[0014] In some embodiments, the rated power of the motor is greater than or equal to 1000W.

[0015] In some embodiments, the voltage of the energy storage device is greater than or equal to 18V.

[0016] In some embodiments, each semiconductor switch uses a MOS tube.

[0017] In some embodiments, an electric tool includes: a housing; an energy storage device configured to supply power to the electric tool; a motor disposed in the housing and including a stator assembly and a rotor assembly; a drive board provided with a plurality of semiconductor switches, wherein a drive circuit formed by the plurality of semiconductor switches is electrically connected to the energy storage device; a controller configured to control the on and off of the plurality of semiconductor switches to regulate the power supply from the energy storage device to the motor; the semiconductor switches are surface mounted in a package, wherein an area occupied by a single semiconductor switch on the drive board is greater than or equal to 1 square centimeter.

[0018] In some embodiments, the driving board includes a circuit layer, an insulating layer, and a metal base layer.

[0019] In some embodiments, the material of the metal base layer is aluminum.

[0020] In some embodiments, the drive plate has a size greater than or equal to 65 square centimeters.

[0021] In some embodiments, the semiconductor switch has a source, a drain, and a gate, wherein the source has 7 pins.

[0022] In some embodiments, the power tool is a wheeled garden tool.

[0023] In some embodiments, the power tool is a push mower.

[0024] In some embodiments, the rated power of the motor is greater than or equal to 1000W.

[0025] In some embodiments, the voltage of the energy storage device is greater than or equal to 18V.

[0026] In some embodiments, each semiconductor switch uses a MOS tube.

[0027] In some embodiments, an electric tool includes: a housing; an energy storage device configured to supply power to the electric tool; a motor disposed in the housing and including a stator assembly and a rotor assembly; a drive board provided with a plurality of semiconductor switches, wherein a drive circuit formed by the plurality of semiconductor switches is electrically connected to the energy storage device; a controller configured to control the on and off of the plurality of semiconductor switches to adjust the power supply from the energy storage device to the motor; the semiconductor switches are surface mounted in a package, wherein the thickness of a single semiconductor switch is less than or equal to 3 mm.

[0028] In some embodiments, the driving board includes a circuit layer, an insulating layer, and a metal base layer.

[0029] In some embodiments, the material of the metal base layer is aluminum.

[0030] In some embodiments, the drive plate has a size greater than or equal to 65 square centimeters.

[0031] In some embodiments, the semiconductor switch has a source, a drain, and a gate, wherein the source has 7 pins.

[0032] In some embodiments, the power tool is a wheeled garden tool.

[0033] In some embodiments, the power tool is a push mower.

[0034] In some embodiments, the rated power of the motor is greater than or equal to 1000W.

[0035] In some embodiments, the voltage of the energy storage device is greater than or equal to 18V.

[0036] In some embodiments, each semiconductor switch uses a MOS tube.

[0037] The benefit of the present application lies in that by setting the packaging form of the semiconductor in the power tool to a surface mount package and at the same time limiting the length and width of each semiconductor switch, the length and width of each semiconductor switch are larger, thereby improving the current and pressure resistance of the semiconductor switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a perspective view of a lawn mower according to an embodiment;

[0039] Figure 2 yes Figure 1 A front view of a motor of a lawn mower;

[0040] Figure 3 yes Figure 1 A perspective view of a drive plate of a lawn mower;

[0041] Figure 4 yes Figure 1 Circuit diagram of the lawn mower in ;

[0042] Figure 5 yes Figure 3 A multi-layer side view of the driver board in FIG.

[0043] Figure 6 yes Figure 3 A stereogram of a driver board including a capacitor;

[0044] Figure 7 yes Figure 3 The driver board in the figure includes a multi-layer side view of a metal heat sink;

[0045] Figure 8 is a side view of a motor connected to a metal base of a driving plate according to an embodiment;

[0046] Fig. 9 is a side view of a motor of an embodiment connected to a circuit layer of a driving board;

[0047] Fig.10 is a side view of a motor of an embodiment connected to a metal heat sink of a driving plate;

[0048] Fig.11 It is a simulation diagram of the radiation value of a stator assembly of an embodiment directly connected to the ground wire of a driving board through a wire;

[0049] Fig.12 It is a simulation diagram of the radiation value of a stator assembly of an embodiment connected to the ground wire of a driving board through a wire after passing through a noise suppression device;

[0050] Fig.13 It is a radiation value simulation diagram of an embodiment in which a stator component is directly connected to a metal base layer of a driving board through a wire. DETAILED DESCRIPTION

[0051] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above drawings.

[0052] In this application, the terms "comprises", "includes", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0053] In this application, the term "and / or" is a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "and / or" relationship.

[0054] In the present application, the terms "connect", "combine", "couple", and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, direct connection refers to two parts or components being connected together without the need for an intermediate piece, and indirect connection refers to two parts or components being connected to at least one intermediate piece respectively, and the two parts or components being connected via the intermediate piece. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical connections or couplings.

[0055] In the present application, it will be understood by those of ordinary skill in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerances caused by manufacturing, assembly, and use associated with a specific value, etc. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0056] In this application, it will be understood by those skilled in the art 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.

[0057] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, the bottom can include directly below, lower left, lower right, lower front, and lower back, etc.

[0058] In this application, the terms "controller", "processor", "central processing unit", "CPU", and "MCU" are interchangeable. When a unit "controller", "processor", "central processing unit", "CPU", or "MCU" is used to perform a specific function, unless otherwise specified, these functions can be performed by a single unit or multiple units.

[0059] In the present application, the terms “device”, “module” or “unit” may be implemented in the form of hardware or software to achieve specific functions.

[0060] In this application, the terms "calculate", "judge", "control", "determine", "identify", etc. refer to the operations and processes of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0061] The electric tools to which the technical solution of the present application is applicable include handheld electric tools, fastening electric tools, cutting electric tools, grinding electric tools, gardening electric tools, etc. For example, electric tools such as hair dryers, electric drills, electric circular saws, reciprocating saws, impact wrenches, impact screwdrivers, hammer drills, lawn mowers, and snow blowers. Other types of electric tools can fall within the protection scope of the present application as long as they can adopt the substantive content of the technical solution disclosed below.

[0062] Figure 1 An electric tool is shown, which may be a wheeled garden tool such as a lawn mower 100 or a snow blower. As an optional embodiment, the electric tool is described below by taking the lawn mower 100 as an example. Specifically, the lawn mower 100 in this embodiment is a hand-push lawn mower.

[0063] Figure 1 The lawn mower 100 is used by a user to cut grass in a lawn, such as a lawn in a garden, a golf course, etc. The grass in the lawn needs to be regularly cared for, so it is necessary to frequently use the lawn mower 100 to mow the lawn. When the user operates the lawn mower 100, the user stands behind the lawn mower 100 and pushes the lawn mower 100 to move on the ground.

[0064] like Figure 1As shown, the lawn mower 100 includes: a handle assembly 110, a main unit 120 and an energy storage device 130. The handle assembly 110 is located at the rear of the main unit 120, and the handle assembly 110 is connected to the main unit 120 through two handle tubes. The handle assembly 110 includes a gripping portion for a user to hold in hand to operate the lawn mower 100, and the lawn mower 100 is pushed by the handle assembly 110 so that the lawn mower 100 moves forward, backward and turns. The main unit 12 includes a housing 121 and a chassis, and the handle assembly 110 is rotatably connected to the housing 121. Among them, the chassis is used to accommodate at least part of the mowing elements used to realize the mowing function of the lawn mower 100. The multiple components included in the above-mentioned main unit 120 are reasonably installed at various parts of the main unit 120. The energy storage device 130 is used to power the lawn mower 100, and the energy storage device 130 includes a battery pack 131 (not shown in the figure) and a connector for installing the battery pack 131 to connect the battery pack 131 to the lawn mower 100. The battery pack 131 is detachably connected to a connector, and the connector is detachably mounted to the lawn mower 100 so that it can be taken out to adapt to other electrical equipment.

[0065] In order to facilitate the description of the technical solution, the following definitions are made: Figure 1 Shown: front, back, left, right, upper, and lower.

[0066] like Figure 1 to Figure 2 As shown, the lawn mower 100 also includes: a running wheel 140 and a motor 150. The running wheel 140 is connected to the main machine 120, and drives the lawn mower 100 to walk on the ground. The running wheel 140 can at least drive the lawn mower 100 to move forward, backward and turn on the ground. The motor 150 is arranged in the housing 121, and the motor 150 includes a stator assembly 151 and a rotor assembly 152. The motor 150 is used to drive the running wheel 140 to rotate. Among them, the running wheel 140 includes two front running wheels and two rear running wheels. In this embodiment, the motor 150 includes two motors, which drive the two rear running wheels respectively. In other embodiments, the motor 150 may also include only one motor, and drive the operation of multiple rear running wheels by one motor. In other embodiments, the motor 150 may also be arranged to drive the front running wheel to rotate, or the lawn mower 100 includes a front drive motor and a rear drive motor, the front drive motor drives the front running wheel, and the rear drive motor drives the rear running wheel.

[0067] like Figure 3 As shown, the lawn mower 100 further includes a driving board 160, on which a plurality of semiconductor switches Q1, Q2, Q3, Q4, Q5, and Q6 are disposed, and the plurality of semiconductor switches Q1-Q6 form a driving circuit 200 that is electrically connected to the energy storage device 130. Figure 4 As shown in the circuit block diagram of the lawn mower 100 , the driving system of the motor 150 may at least include a driving circuit 200 , a power supply 210 and a controller 220 .

[0068] In some embodiments, the motor 150 is a brushless DC motor (BLDC). In some embodiments, the motor 150 is a sensorless BLDC. In some embodiments, the motor 150 is an inductive BLDC. In the present application, the brushless DC motor can be an inner rotor motor or an outer rotor motor, and the motor 150 includes at least three-phase stator windings A, B, and C, and the three-phase windings can be star-connected or delta-connected.

[0069] In some embodiments, the power supply 210 can be selected as an AC power supply, that is, a 120V or 220V AC mains power supply can be connected through a power interface. In some embodiments, the power supply 210 can be selected as a battery pack, and the battery pack can be composed of a group of battery cells. For example, the battery cells can be connected in series into a single power branch to form a 1P battery pack. In the present application, the power supply 210 is specifically described as a battery pack 131 as an example. The output voltage of the battery pack 131 is changed through a specific power control module, such as a DC-DC module, and a power supply voltage suitable for the drive circuit 200, the motor 150, etc. is output to power them. Those skilled in the art will understand that the DC-DC module is a mature circuit structure and can be selected accordingly according to the specific parameter requirements of the power tool.

[0070] The drive circuit 200 is electrically connected to the stator windings A, B, and C of the motor 150, and is used to transfer the current from the power supply 210 (i.e., the battery pack 131) to the stator windings A, B, and C to drive the motor 150 to rotate. In some embodiments, the drive circuit 200 includes a plurality of semiconductor switches Q1, Q2, Q3, Q4, Q5, and Q6, and the gate terminal of each semiconductor switch is electrically connected to the controller 220 to receive a control signal from the controller 220. The drain or source of each semiconductor switch is connected to the stator windings A, B, and C of the motor 150. The semiconductor switches Q1-Q6 receive the control signal from the controller 220 to change their respective conduction states, thereby changing the current loaded by the power supply 210 on the stator windings A, B, and C of the motor 150. In some embodiments, the drive circuit 200 can be a three-phase bridge driver circuit including six controllable semiconductor power devices (such as FET, BJT, IGBT, etc.). It is understandable that the semiconductor switch mentioned above may also be any other type of solid-state switch, such as an insulated gate bipolar transistor (IGBT), a bipolar junction transistor (BJT), etc.

[0071] In some embodiments, reference Figure 5The driving board 160 shown in the figure includes a circuit layer 161, an insulating layer 162 and a metal base layer 163, wherein the circuit layer 161 is used to connect the circuit elements in the lawn mower 100. Specifically, the circuit layer 161 can be etched to form a printed circuit to realize the assembly and connection of each circuit element. The metal base layer 163 supports the driving board 160 and can absorb the heat generated when the driving board 160 and the circuit elements are working. Optionally, in order to enhance the heat dissipation effect of the driving board 160, the metal base layer 163 and the circuit layer 161 are made of thermally conductive materials. The insulating layer 162 is arranged between the circuit layer 161 and the metal base layer 163 to insulate the circuit layer 161 and the metal base layer 163.

[0072] In some embodiments, the circuit layer 161 is made of a first conductive material, and the first conductive material can be a metal copper foil or aluminum foil. The insulating layer 162 is made of an insulating material, and can be an insulating material with good thermal conductivity and insulation properties such as ceramic polymer. The metal base layer 163 is made of a second conductive material, and the second conductive material can be metal copper, aluminum, iron or stainless steel, etc. The metal base layer 163 can be a copper plate, an aluminum plate, an iron plate or a stainless steel plate, etc. Among them, since aluminum has good thermal conductivity, electrical insulation and mechanical processing properties compared to other conductive materials, the metal base layer 163 is selected as an aluminum plate, which is conducive to the diffusion of heat when the driving board 160 is working. Optionally, a plurality of semiconductor switches Q1-Q6 are arranged on the driving board 160, specifically on the metal base layer 163, that is, on the aluminum plate.

[0073] In some embodiments, Figure 6 As shown, a plurality of capacitors C are also provided on the driving board 160. Optionally, the capacitor C and a plurality of semiconductor switches Q1-Q6 are respectively provided on both sides of the driving board 160, that is, the capacitor C is specifically provided on the circuit layer 161. Optionally, the pin on the capacitor C passes through the circuit layer 161 to contact the metal base layer 163, and is fixed on the metal base layer 163. Among them, the metal base layer 163 and the capacitor C are insulated from each other. Specifically, the driving board 160 includes an insulator, which is arranged between the capacitor C and the metal base layer 163 to insulate the capacitor C from the metal base layer 163. In the present application, the insulator includes, but is not limited to: a dispensing insulating pad and / or an insulating sleeve.

[0074] In some embodiments, the size of the drive plate 160 is greater than or equal to 65 square centimeters. Optionally, the length of the drive plate 160 can be 90 mm and the width can be 76 mm, that is, the size of the drive plate 160 can be 68.4 square centimeters. Optionally, the size of the drive plate 160 can be 70 square centimeters. Optionally, the size of the drive plate 160 can be 73.5 square centimeters. Optionally, the size of the drive plate 160 can be 80 square centimeters. Optionally, the size of the drive plate 160 can be 95 square centimeters.

[0075] In some embodiments, the semiconductor switches Q1-Q6 on the driving board 160 are all surface mounted packages. The surface mounted packages include D-PAK packages, SOT packages, SOP packages, QFP packages, PLCC packages, and TOLL packages. Optionally, the semiconductor switches Q1-Q6 can be TOLL packages. The semiconductor switches Q1-Q6 include a source, a drain, and a gate, wherein when the semiconductor switches Q1-Q6 are TOLL packages, the source has 7 pins.

[0076] In some embodiments, the length L and width W of any semiconductor switch of the semiconductor switches Q1-Q6 are both greater than or equal to 9 mm. Optionally, the length L and the width W may both be 9 mm. Optionally, the length L may be 11 mm. Optionally, the length L may be 11.48 mm. Optionally, the length L may be 11.7 mm. Optionally, the length L may be 12.5 mm. Optionally, the length L may be 14.5 mm. Optionally, the width W may be 9.7 mm. Optionally, the width W may be 9.9 mm. Optionally, the width W may be 11.3 mm. Optionally, the width W may be 12.45 mm.

[0077] In some embodiments, the area occupied by any semiconductor switch of the semiconductor switches Q1-Q6 on the driving board 160 is greater than or equal to 1 square centimeter. Optionally, the area occupied by any semiconductor switch on the driving board 160 may be 1.11 square centimeters. Optionally, the area occupied by any semiconductor switch on the driving board 160 may be 1.15 square centimeters. Optionally, the area occupied by any semiconductor switch on the driving board 160 may be 1.2 square centimeters. Optionally, the area occupied by any semiconductor switch on the driving board 160 may be 1.35 square centimeters.

[0078] In some embodiments, the thickness H of any semiconductor switch among the semiconductor switches Q1-Q6 is less than or equal to 3 mm. Optionally, the thickness H may be 2.85 mm. Optionally, the thickness H may be 2.6 mm. Optionally, the thickness H may be 2.3 mm. Optionally, the thickness H may be 1.5 mm.

[0079] Compared with other packaging methods, TOLL packaging has a smaller thickness. The smaller thickness means that the thickness of the semiconductor switch of TOLL packaging is smaller. And compared with other packaging methods, TOLL packaging requires fewer parallel components in the application, and the current and voltage resistance of TOLL packaging are better, so that each semiconductor switch can achieve good current and voltage resistance performance by using only one MOS tube, avoiding the disadvantages of other packaging methods in the prior art that each semiconductor needs to use two MOS tubes in parallel to have sufficient current and voltage resistance. Therefore, in terms of the packaging area required for each semiconductor switch, TOLL packaging only needs one MOS tube, and the area occupied by the semiconductor switch using TOLL packaging is smaller than the area occupied by other packaging methods. TOLL packaging also has a higher power density, and TOLL packaging has ultra-low on-resistance and parasitic inductance, as well as excellent EMI performance and thermal performance.

[0080] In addition, the TOLL package also has a lower temperature rise, so the use of the TOLL package for the semiconductor switches Q1-Q6 on the driver board 160 can reduce the cooling requirements of the semiconductor switches. At the same time, since the metal base layer 163 of the driver board 160 is an aluminum plate, the aluminum plate has a good heat dissipation effect, and combined with the TOLL package, the heat dissipation effect of the semiconductor switches Q1-Q6 is even better. For example, at an ambient temperature of 26°C, when passing the continuous 40A overcurrent capacity test, the ordinary PCB board uses the TOLL package and the heat is dissipated through the PCB, and the temperature rise at this time is only 61 degrees Celsius. When the TOLL package is used on the aluminum plate and the heat is dissipated through the aluminum plate, the temperature rise at this time is further greatly reduced to only 32 degrees Celsius.

[0081] In some embodiments, the rated power of the motor 150 is greater than or equal to 1000W. Optionally, the rated power of the motor 150 is 1200W. Optionally, the rated power of the motor 150 is 1500W. Optionally, the rated power of the motor 150 is 1800W. Optionally, the rated power of the motor 150 is 2000W. Optionally, the rated power of the motor 150 is 2500W. In some embodiments, the voltage of the energy storage device 130 is greater than or equal to 18V. Optionally, the voltage of the energy storage device 130 is 24V. Optionally, the voltage of the energy storage device 130 is 36V. Optionally, the voltage of the energy storage device 130 is 48V. Optionally, the voltage of the energy storage device 130 is 56V. Optionally, the voltage of the energy storage device 130 is 72V. When the rated power of the motor 150 is large, or the voltage of the energy storage device 130 is large, since the TOLL package used in the semiconductor switches Q1-Q6 in this application can withstand a large current and is not easily broken down, the safety and reliability of the driving board 160 are improved.

[0082] Overall, TOLL packaging can bring higher reliability, higher efficiency and lower cost compared to other methods.

[0083] Therefore, the present application limits the metal base layer 163 of the driving board 160 to an aluminum plate, and combines the semiconductor switches Q1-Q6 on the driving board 160 with the TOLL package, that is, the TOLL-packaged MOS tube is applied to the aluminum plate in the power tool, so that each semiconductor switch only needs to use one MOS, and the semiconductor switch has better current resistance and voltage resistance performance.

[0084] In some embodiments, the diameter of the motor 150 is greater than or equal to 60 mm. Alternatively, the diameter of the motor 150 may be 65 mm. Alternatively, the diameter of the motor 150 may be 70 mm. In some embodiments, the diameter of the motor 150 is greater than or equal to 90 mm. Alternatively, the diameter of the motor 150 may be 100 mm. Alternatively, the diameter of the motor 150 may be 120 mm. Alternatively, the diameter of the motor 150 may be 150 mm.

[0085] In some embodiments, the rated speed of the motor 150 is greater than or equal to 2000 rpm. Optionally, the rated speed of the motor 150 is 2200 rpm. Optionally, the rated speed of the motor 150 is 2200 rpm. Optionally, the rated speed of the motor 150 is 2500 rpm. Optionally, the rated speed of the motor 150 is 2800 rpm. Optionally, the rated speed of the motor 150 is 3000 rpm.

[0086] In some embodiments, the lawn mower 100 further includes a metal heat sink 164. Figure 7 As shown, the metal heat sink 164 is disposed on the driving board 160, and the metal heat sink 164 is connected to the metal base layer 163. Optionally, the metal heat sink 164 includes a plurality of heat sinks disposed in parallel, and the heat sinks protrude in a direction perpendicular to the metal base layer 163. Optionally, the metal heat sink 164 may also be directly composed of heat sink fins. In some embodiments, a heat conductive layer 165 is further disposed between the metal base layer 164 and the metal heat sink 164, and the heat conductive layer 165 absorbs the heat of the metal base layer 164 and dissipates the heat through the metal heat sink 164 to reduce the temperature of the driving board 160. Optionally, the heat conductive layer 165 may be made of a thermally conductive interface material, such as thermally conductive silicone. By setting the heat conductive layer 165, the heat dissipation effect on the driving board 160 can be further enhanced.

[0087] In order to reduce the radiation interference of the motor 150 , it is necessary to connect the stator component 151 of the motor 150 to a metal component, or to ground the stator component 151 .

[0088] In some embodiments, the stator assembly 151 of the motor 150 is directly connected to the metal base layer 163 of the driving board 160 through the wire 300 to reduce the radiation interference of the motor 150. The stator assembly 151 is directly connected to the metal base layer 163 through the wire 300, which means that the stator assembly 151 is not connected to the metal base layer 163 via a noise suppression device. Optionally, the noise suppression device includes a capacitor and a magnetic ring.

[0089] In some embodiments, when the motor 150 is an inner rotor motor, one end of the wire 300 is connected to the stator core of the stator assembly 151, and the other end is connected to the metal base 163. In some embodiments, when the motor 150 is an outer rotor motor, one end of the wire 300 is connected to the stator end cover of the stator assembly 151, and the other end is connected to the metal base 163. Figure 8 As shown, the present application takes the motor 150 as an inner rotor motor as an example, and the two ends of the wire 300 are respectively connected to the stator core of the stator assembly 151 and the metal base layer 163, so as to reduce the radiation interference of the motor 150.

[0090] In some embodiments, the stator assembly 151 of the motor 150 is directly connected to the drive board 160 via a wire 300 to reduce the radiation interference of the motor 150, without going through a noise suppression device. Among them, the stator assembly 151 of the motor 150 is specifically connected to the ground wire of the drive board 160 via a wire 300 to reduce the radiation interference of the motor 150, that is, it is connected to the ground wire on the circuit layer 161 in the drive board 160. When the motor 150 is an inner rotor motor or an outer rotor motor, the specific connection method between the stator assembly 151 and the drive board 160 is the same as the specific connection method between the stator assembly 151 and the metal base layer 163, which will not be repeated here. Fig. 9 As shown, the motor 150 is taken as an inner rotor motor and is connected to the driving board 160 through a wire 300 .

[0091] In some embodiments, the stator assembly 151 of the motor 150 is directly connected to the housing 121 through the wire 300 to reduce the radiation interference of the motor 150, without going through the noise suppression device. The present application does not limit the specific position where the wire 300 is connected to the housing 121, and the wire 300 can be connected to any position of the housing 121. Optionally, the wire 300 can be preferably connected to the housing 121 at the shortest distance from the stator assembly 151.

[0092] In some embodiments, the stator assembly 151 of the motor 150 can also be directly connected to the metal heat sink 164 through the wire 300 to reduce the radiation interference of the motor 150 without going through the noise suppression device. Similarly, when the motor 150 is an inner rotor motor or an outer rotor motor, the specific connection method of the stator assembly 151 and the housing 121 or the metal heat sink 164 is the same as the specific connection method of the stator assembly 151 and the metal base layer 163, which will not be repeated here. Fig.10 As shown, the motor 150 is taken as an inner rotor motor and is connected to the metal heat sink 164 through a wire 300 .

[0093] In some embodiments, Fig.11 It is a simulation diagram of the radiation value when the stator assembly 151 is directly connected to the ground wire of the driving board 160 through the wire 300. Fig.12 This is a simulation diagram of the radiation value of the stator assembly 151 connected to the ground wire of the driving board 160 through the wire 300 after passing through the noise suppression device. Fig.11 and Fig.12 The horizontal axis is the frequency, the vertical axis is the radiation value, and the straight line along the horizontal axis is the maximum radiation limit value corresponding to different frequencies. Fig.11 and Fig.12 It can be seen that compared with Fig.11 , Fig.12 After the noise suppression device is used, the actual radiation values ​​corresponding to different frequencies are lower than the corresponding maximum radiation limits, and the noise suppression device is indeed better in reducing the radiation interference of the motor 150. However, the magnetic ring or capacitor included in the noise suppression device will occupy the internal space of the lawn mower 100 and consume higher costs. Fig.11 It can be seen from the figure that although the effect of reducing the radiation interference of the motor 150 is not significant, the stator assembly 151 is directly connected to the ground wire of the driving board 160 through the wire 300. Fig.12 Good, but it will not exceed the maximum radiation limit. At this time, it can basically meet the needs of reducing radiation interference.

[0094] In some embodiments, Fig.13 3 is a simulation diagram of the radiation value of the stator assembly 151 directly connected to the metal base 163 of the driving board 160 through the wire 300. Fig.13 It can be clearly seen that compared with Fig.11 and Fig.12 , Fig.13 The actual radiation values ​​corresponding to different frequencies are significantly lower than the corresponding maximum radiation limits. For example, in the range of 30MHz to 60MHz, Fig.11 The actual radiation value is almost close to 30dBuV / m. Fig.12The actual radiation value corresponding to 50MHz to 60MHz is also almost close to 30dBuV / m. Fig.13 The actual radiation value fluctuates around 25dBuV / m.

[0095] In some embodiments, Fig.11 , Fig.12 and Fig.13 The three types of corresponding reduction of the radiation interference of the motor 150 are described in detail with two point values, as shown in Table 1 below. It can be concluded from Table 1 that when the stator assembly 151 is directly connected to the ground wire of the drive board 160 through the wire 300, the actual radiation value corresponding to 40.7185MHz is 30.42dBuV / m, and when the stator assembly 151 is directly connected to the metal base layer 163 of the drive board 160 through the wire 300, the actual radiation value corresponding to 31.5035MHz is 24.87dBuV / m. Although 31.5035MHz is less than 40.7185MHz, the actual radiation value 24.87dBuV / m is less than 30.42dBuV / m. It can be seen that the effect of reducing the radiation interference of the motor 150 when the stator assembly 151 is directly connected to the metal base layer 163 of the drive board 160 through the wire 300 is significantly better than when the stator assembly 151 is directly connected to the ground wire of the drive board 160 through the wire 300. Similarly, the stator component 151 is connected to the ground line of the drive board 160 through the wire 300 via the noise suppression device, and the corresponding 28dBuV / m is compared with the 54.8805MHz corresponding 21.43dBuV / m of the metal base layer 163 of the drive board 160 directly connected to the stator component 151 through the wire 300. It can also be seen that the effect of reducing the radiation interference of the motor 150 by directly connecting the stator component 151 to the metal base layer 163 of the drive board 160 through the wire 300 is significantly better than that of directly connecting the stator component 151 to the ground line of the drive board 160 through the wire 300.

[0096] Therefore, directly connecting the stator assembly 151 to the metal base layer 163 of the driving board 160 through the wire 300 has the best effect in reducing the radiation interference of the motor 150 .

[0097] Table 1

[0098]

[0099] Therefore, the present application does not need to use a noise suppression device, and while saving costs and the internal space of the lawn mower 100, the stator assembly 151 of the motor 150 is directly connected to the ground wire of the drive board 160 or the metal base layer 163 of the drive board 160, or the housing 121, or the metal heat sink 164 through the wire 300, which can also reduce the radiation interference of the motor 150. Moreover, the effect of reducing the radiation interference of the motor 150 by directly connecting the stator assembly 151 of the motor 150 to the metal base layer 163 of the drive board 160 through the wire 300 is significantly better than using a noise suppression device.

[0100] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above embodiments do not limit the present application in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. An electric tool comprising: case; an energy storage device configured to supply power to the electric tool; A motor, disposed in the housing, comprising a stator assembly and a rotor assembly; A driving board, provided with a plurality of semiconductor switches, wherein a driving circuit formed by the plurality of semiconductor switches is electrically connected to the energy storage device; a controller configured to control the on and off of the plurality of semiconductor switches to regulate the power supply from the energy storage device to the motor; It is characterized in that the semiconductor switch adopts a surface mount package, wherein the length and width of a single semiconductor switch are both greater than or equal to 9 mm.

2. The electric tool according to claim 1, characterized in that: The driving board includes a circuit layer, an insulating layer and a metal base layer.

3. The electric tool according to claim 2, characterized in that: The material of the metal base layer is aluminum.

4. The electric tool according to claim 1, characterized in that: The driving plate has a size greater than or equal to 65 square centimeters.

5. The electric tool according to claim 1, wherein: The semiconductor switch has a source, a drain and a gate, wherein the source has 7 pins.

6. The electric tool according to claim 1, wherein: The electric tool is a wheeled gardening tool.

7. The electric tool according to claim 1, wherein: The electric tool is a hand-push lawn mower.

8. The electric tool according to claim 1, wherein: The rated power of the motor is greater than or equal to 1000W.

9. The electric tool according to claim 1, wherein: The voltage of the energy storage device is greater than or equal to 18V.

10. The electric tool according to claim 1, wherein: Each of the semiconductor switches uses a MOS tube.

11. An electric tool comprising: case; an energy storage device configured to supply power to the electric tool; A motor, disposed in the housing, comprising a stator assembly and a rotor assembly; A driving board, provided with a plurality of semiconductor switches, wherein a driving circuit formed by the plurality of semiconductor switches is electrically connected to the energy storage device; a controller configured to control the on and off of the plurality of semiconductor switches to regulate the power supply from the energy storage device to the motor; It is characterized in that the semiconductor switch adopts a surface mount package, wherein the occupied area of ​​a single semiconductor switch on the driving board is greater than or equal to 1 square centimeter.

12. The electric tool according to claim 11, wherein: The driving board includes a circuit layer, an insulating layer and a metal base layer.

13. The electric tool according to claim 12, wherein: The material of the metal base layer is aluminum.

14. The electric tool according to claim 11, wherein: The driving plate has a size greater than or equal to 65 square centimeters.

15. The electric tool according to claim 11, wherein: The semiconductor switch has a source, a drain and a gate, wherein the source has 7 pins.

16. The electric tool according to claim 11, wherein: The electric tool is a wheeled gardening tool.

17. The electric tool according to claim 11, wherein: The electric tool is a hand-push lawn mower.

18. The electric tool according to claim 11, wherein: The rated power of the motor is greater than or equal to 1000W.

19. The electric tool according to claim 11, wherein: The voltage of the energy storage device is greater than or equal to 18V.

20. The electric tool according to claim 11, wherein: Each of the semiconductor switches uses a MOS tube.

21. An electric tool comprising: case; an energy storage device configured to supply power to the electric tool; A motor, disposed in the housing, comprising a stator assembly and a rotor assembly; A driving board, provided with a plurality of semiconductor switches, wherein a driving circuit formed by the plurality of semiconductor switches is electrically connected to the energy storage device; a controller configured to control the on and off of the plurality of semiconductor switches to regulate the power supply from the energy storage device to the motor; It is characterized in that the semiconductor switch adopts a surface mount package, wherein the thickness of a single semiconductor switch is less than or equal to 3 mm.

22. The electric tool according to claim 21, characterized in that The driving board includes a circuit layer, an insulating layer and a metal base layer.

23. The electric tool according to claim 22, characterized in that: The material of the metal base layer is aluminum.

24. The electric tool according to claim 21, wherein: The driving plate has a size greater than or equal to 65 square centimeters.

25. The electric tool according to claim 21, wherein: The semiconductor switch has a source, a drain and a gate, wherein the source has 7 pins.

26. The electric tool according to claim 21, wherein: The electric tool is a wheeled gardening tool.

27. The electric power tool according to claim 21, wherein: The electric tool is a hand-push lawn mower.

28. The electric tool according to claim 21, wherein: The rated power of the motor is greater than 1000W.

29. The electric tool according to claim 21, wherein: The voltage of the energy storage device is greater than or equal to 18V.

30. The electric tool according to claim 21, wherein: Each of the semiconductor switches uses a MOS tube.

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