BRUSHLESS MOTOR FOR A POWER TOOL

Abstract

An electric tool comprises a housing and an electric motor, the electric motor comprising a rotor and a stator. The rotor is coupled to a motor shaft having a spindle section that carries an output unit. The stator comprises a core, an insulator coupled to the core and having an end cap section positioned at an axial end of the stator, and a winding forming a coil. The stator further comprises a terminal designed to electrically connect the winding to a power source. The terminal is supported by the end cap section. The terminal comprises a main body section, a bracket, and a phase-connection section. The main body section is in contact with the end cap section and is generally flat, extending away from the end cap section in an axial direction of the electric motor. The bracket extends away from the main body section in a radial direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Chinese Utility Model Application No. 202322636474.2, now Chinese Patent No. ZL202322636474.2, filed on September 27, 2023, the entire contents of which are incorporated herein by reference. AREA

[0002] The present disclosure relates to electric motors and, more particularly, to brushless DC electric motors. BACKGROUND

[0003] Power tools generally have a motor connected to a power source to drive the tool. This type of motor is a brushed direct current (DC) motor. In brushed DC motors, motor brushes make and break the electrical connection to the motor due to the rotation of the rotor. Traditionally, brushed DC motors were used in power tools because of their relatively simple manufacturing and low cost.

[0004] Brushed DC motors have several disadvantages when used in power tools. One disadvantage of brushed DC motors is that the brushes eventually wear out, reducing the lifespan of the power tool. Because the brushes make and break the electrical connection, sparks and electrical noise can occur in the power tool. A brushless DC motor is another type of motor used in power tools. A brushless DC motor uses electronically controlled switches to selectively supply power to a motor's coils to drive a rotor, instead of brushes. SUMMARY

[0005] The present disclosure, in one embodiment, provides a power tool having a housing with a motor housing portion and a handle portion. The power tool further includes an electric motor supported within the motor housing portion and having a rotor and a stator. The rotor is coupled to a motor shaft. The motor shaft has a spindle portion supporting an output unit. The stator includes a core, an insulator coupled to the core and having an end cap portion positioned at an axial end of the stator, and a winding forming a coil. The stator further includes a terminal configured to electrically connect the winding to a power source. The terminal is supported by the end cap portion. The terminal includes a main body portion, a yoke, and a phase connection portion.The main body portion of the terminal is in contact with the end cap portion and is generally planar, extending away from the end cap portion in an axial direction of the electric motor. The yoke extends away from the main body portion in a radial direction of the electric motor and is bent toward the axial direction. The yoke is designed for mechanical and electrical connection to the winding. The phase connection portion extends away from the main body portion in a circumferential direction perpendicular to the axial direction. The phase connection portion is designed for mechanical and electrical connection to a phase wire designed to supply power from the power source.

[0006] The present disclosure, in another embodiment, provides a power tool having a housing with a motor housing portion and a handle portion. The power tool also includes an electric motor supported within the motor housing portion and having a rotor and a stator, the rotor coupled to a motor shaft. The stator includes a core, an insulator coupled to the core and having an end cap portion positioned at an axial end of the stator, and a winding forming a first coil and a second coil. The stator further includes a terminal configured to electrically connect the winding to a power source, the terminal being carried by the end cap portion. The terminal includes a main body portion, a yoke, and a phase connection portion.The main body portion is in contact with the end cap portion and is generally planar and extends away from the end cap portion in an axial direction of the electric motor. The yoke extends away from the main body portion in a radial direction of the electric motor and is bent toward the axial direction, the yoke being configured for mechanical and electrical connection to the winding. The winding includes an elongated wire wound around the end cap portion to form the first coil and the second coil. The elongated wire further forms a transition portion extending around at least a portion of a circumference of the insulator to electrically connect the first coil to the second coil.

[0007] A power tool includes a housing having a motor housing portion and a handle portion. The power tool also includes an electric motor mounted within the motor housing portion, the motor having a stator, a rotor coupled to a motor shaft, and a printed circuit board assembly (LPA). The stator includes a core, an insulator coupled to the core and having an end cap portion positioned at an axial end of the stator, and a winding forming a coil. The stator further includes a terminal configured to electrically connect the winding to a power source, the terminal being supported by the end cap portion. The terminal includes a main body portion, a yoke, and a phase connection portion. The main body portion of the terminal is in contact with the end cap portion and is generally planar and extends away from the end cap portion in an axial direction of the electric motor.The bracket extends away from the main body portion in a radial direction of the electric motor and is bent toward the axial direction. The bracket is designed for mechanical and electrical connection to the winding. The phase connection portion extends away from the main body portion in a circumferential direction perpendicular to the axial direction. The phase connection portion is designed for mechanical and electrical connection to the LPA.

[0008] Before embodiments are explained in more detail, it is to be understood that the embodiments are not limited in their application to the details of the design and arrangement of components set forth in the following description or illustrated in the accompanying drawings. The embodiments may be practiced or carried out in a variety of ways. Further, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be considered limiting. The use of "comprising" or "having" / "with" and variations thereof is intended to include the elements listed thereafter and their equivalents as well as additional elements. Unless otherwise specified or limited, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly to include both direct and indirect mountings, connections, supports, and couplings.

[0009] Furthermore, it should be understood that the embodiments may include hardware, software, and electronic components or modules, which, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented only in hardware. However, one of ordinary skill in the art, based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic-based aspects may be implemented in software (e.g., stored on a non-transitory computer-readable medium) that may be executed by one or more processing units, such as a microprocessor and / or application-specific integrated circuits ("ASICs"). Thus, it should be appreciated that multiple hardware- and software-based devices, as well as multiple different structural components, may be used to implement the embodiments.For example, “servers,” “computing devices,” “controllers,” “processors,” etc., described in the specification may include one or more processing units, one or more computer-readable media modules, one or more input / output interfaces, and various connections (e.g., a system bus) connecting the components.

[0010] Relative terminology, such as "about," "approximately," "substantially," etc., used in connection with a quantity or condition would be understood by one of ordinary skill in the art to include the stated value and to have the meaning determined by the context (e.g., the term includes at least the degree of error associated with the accuracy of measurement, tolerances [e.g., manufacturing, assembly, use, etc.] associated with the particular value, etc.). Such terminology should also be understood to include the range defined by the absolute values ​​of the two endpoints. For example, the phrase "from about 2 to about 4" also includes the range "from 2 to 4." Relative terminology can refer to plus or minus one percentage (e.g., 1%, 5%, 10%, or more) of a stated value.

[0011] Although certain drawings depict hardware and software residing within particular devices, it should be understood that these images are for illustrative purposes only. Functions performed by one component in the present description may be performed by multiple components in a distributed manner. Likewise, functions performed by multiple components may be consolidated and performed by a single component. In some embodiments, the depicted components may be combined or separated into separate software, firmware, and / or hardware. For example, rather than residing and being executed by a single electronic processor, logic and processing may be distributed among multiple electronic processors.Regardless of how they are combined or divided, hardware and software components may be located on the same computing device or may be distributed among different computing devices connected by one or more networks or other suitable communication links. Likewise, a component described as performing a particular functionality may also perform additional functionality not described herein. For example, a device or structure "designed" in a particular manner is at least designed in that manner, but may also be configured in ways not explicitly listed.

[0012] Further aspects of the embodiments will become apparent upon consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a side view of a power tool according to an embodiment of the disclosure. Fig. 2 shows a cross-sectional view of the power tool of Fig. 1 with an electric motor according to an embodiment described here. Fig. Figure 3 shows a block diagram of a power tool, such as the power tool of Fig. 1. Fig. 4A and Fig. 4B show perspective views of the electric motor of Fig. 2. Fig. Figure 4C shows a perspective view of sections of the electric motor of Fig. 2. Fig. Figure 4D shows an axial end view of the electric motor of Fig. 2. Fig. 4E shows a perspective detail view of a portion of the electric motor of Fig. 2. Fig. Figure 4F shows a detailed axial end view of a partial section of the electric motor of Fig. 2. Fig. 5 shows a method for hot riveting a printed circuit board assembly (LPA) to a stator of an electric motor, such as the electric motor Fig. 2. Fig. 6A and Fig. 6B show perspective views of an electric motor according to another embodiment of the disclosure. Fig. Figure 6C shows a perspective view of sections of the electric motor of Fig. 6A. Fig. 6D shows a perspective detailed view of a section of the electric motor of Fig. 6A. Fig. 7A and Fig. 7B show perspective views of an electric motor according to another embodiment of the disclosure. Fig. Figure 7C shows a perspective view of sections of the electric motor of Fig. 7A. Fig. Figure 7D shows an axial end view of the electric motor of Fig. 7A. Fig. 7E shows a perspective detail view of a portion of the electric motor of Fig. 7A. Fig. 7F shows a cross-sectional view of a portion of the electric motor of Fig. 7A along the line 7F-7F from Fig. 7C. Fig. 8 shows a perspective view of an electric motor according to another embodiment of the disclosure. DETAILED DESCRIPTION

[0013] Fig. 1 shows a power tool 100 having a brushless direct current (DC) motor 101 ( Fig. 2). In a brushless motor power tool, such as power tool 100, switching elements are selectively activated and deactivated by control signals from a controller to selectively apply power from a power source (e.g., battery pack) to drive a brushless motor. Power tool 100 is illustrated as a small angle grinder having a housing 102 with a handle portion 104 and a motor housing portion 106. Power tool 100 further includes a drive unit 108 and a battery pack interface 110. Although Fig. 1 illustrates a small angle grinder, in some embodiments, the motors described herein are incorporated into other types of power tools, including drills / drivers, impact drivers, circular saws, reciprocating saws, string trimmers, leaf blowers, vacuum cleaners, and the like.

[0014] Fig. 2 shows a cross-sectional view of the power tool 100. The motor 101 is mounted in the motor housing portion 106 and operatively coupled to the output unit 108. In the illustrated embodiment, the power tool 100 comprises a direct drive arrangement in which the motor 101 is directly coupled to the output unit 108 without an intermediate reduction gear. The motor 101 includes a stationary stator 112 and a rotor 114 rotatably mounted on a motor shaft 116. As shown in Fig. 2, the motor shaft 116 extends beyond one end of the rotor 114 and includes a spindle portion 118 that supports the output unit 108.

[0015] Fig. 3 illustrates a simplified block diagram 120 of the power tool 100, including a power source 122, field-effect transistors (FETs) 124, the motor 101, Hall-effect sensors 128, a motor controller 130, a user input 132, and other components 133 (battery pack charge indicator, work lights (LEDs), current / voltage sensors, etc.). The power source 122 supplies DC power to the various components of the power tool 100 and may be a power tool battery pack that is rechargeable and uses, for example, lithium-ion cell technology. In some cases, the power source 122 may receive AC power (e.g., 120 V / 60 Hz) from a tool plug coupled to a standard wall outlet and then filter, condition, and rectify the received power to output DC power.Each Hall-effect sensor 128 outputs motor feedback information, such as an indication (e.g., a pulse) when a magnet of rotor 114 sweeps across the face of that Hall sensor. Based on the motor feedback information from Hall sensors 128, motor controller 130 can determine the position, speed, and acceleration of rotor 114. Motor controller 130 also receives user controls from user input 132, such as by activating an on / off switch (not shown). In response to the motor feedback information and user controls, motor controller 130 transmits control signals to control FETs 124 to drive motor 101. By selectively activating and deactivating FETs 124, power from power source 122 is selectively applied to stator coils of motor 101 to cause rotation of rotor 114.Although not shown, the motor controller 130 and other components of the power tool 100 are electrically coupled to the power source 122 such that the power source 122 provides power thereto.

[0016] Various embodiments of the engine 101 are described with reference to the Fig. 4A-7D shown and described.

[0017] Fig. 4A-4F illustrate the motor 101 according to one embodiment. The stator 112 includes a stator core 134 and an insulator 136 attached to the stator core 134. In some embodiments, the stator core 134 may be formed as a lamination stack having a plurality of flat, thin laminations stacked together along an axial direction of the stator core 134. The stator core 134 includes an annular yoke 138 and a plurality of teeth 140 (e.g., six teeth in the illustrated embodiment) projecting radially inward from the yoke 138. Windings 142 are wound around the teeth 140 to form coils 144. In some embodiments, the windings 142 may be formed entirely from a single insulated wire 143 wound around the teeth 140 to form all of the coils 144. The windings 142 are electrically insulated from the stator core 134 by the insulator 136.In some embodiments, the insulator 136 may be formed from resin by injection molding.

[0018] As with regard to Fig. 4A-4C, the motor 101 also includes a terminal assembly 146 that includes a plurality of terminals 148 for electrically connecting the coils 144 in a winding arrangement. In the illustrated embodiment, the terminal assembly 146 includes three terminals 148, each supported by the insulator 136 at a first axial end 150 of the motor 101. More specifically, the insulator 136 includes a first end cap portion 152 disposed at the first axial end 150 and a second end cap portion 154 disposed at the opposite second axial end 156, and the terminals 148 are supported on the first end cap portion 152. The terminals 148 are spaced apart from one another about a longitudinal axis 158 of the motor 101. In the illustrated embodiment, the terminals 148 are spaced at equal angular intervals of approximately 120 degrees from each other.

[0019] As in Fig. 4C-4F, each terminal 148 includes a main body portion 160, a winding connection portion or bracket 162, and a phase connection portion 164. The main body portion 160 of each terminal 148 is generally flat (i.e., planar) and extends generally in an axial direction and, in its longest dimensions, generally in a circumferential direction. The bracket 162 of each terminal 148 is generally elongated and bent in a hook-like manner. The bracket 162 projects radially outward from the main body portion 160 and then bends away from the insulator 136 and toward the axial direction. The phase connection portion 164 of each terminal 148 extends laterally away from the main body portion 160 generally in the circumferential direction of the motor 101. The phase connection portion 164 is also generally flat (i.e., planar) and extends away from the main body portion 160 in one direction (e.g.,lateral direction) that is perpendicular to the axial direction and perpendicular to the longitudinal axis 158. This reduces an overall length of the motor 101 because the phase connection portion 164 does not extend axially beyond the main body portion 160. The phase connection portion 164 is also generally flat (i.e., planar) and defines an obtuse angle A with the main body portion 160. In the illustrated embodiment, the angle A is approximately 150 degrees. In other embodiments, the obtuse angle A may be greater than 90 degrees and less than 180 degrees. In further embodiments, the obtuse angle A may be greater than 110 degrees and less than 170 degrees such that the phase connection portion 164 is bent toward the curvature of the stator 112 and generally remains within a footprint or projection area of ​​the stator 112.The angle A reduces an overall diameter of the motor 101 because the phase connection portion 164 does not radially protrude beyond an outer circumferential surface of the stator 112, but rather follows the curvature of the yoke 138.

[0020] As with regard to Fig. 4C-4F, the windings 142 are mechanically and electrically connected to the terminals 148. The windings 142, which in the illustrated embodiment are formed from a single elongated wire 143, more particularly include a pair of wire ends or leads 166 connected to the bracket 162 of the at least one terminal 148. The windings 142 are also connected to the bracket 162 of each of the terminals 148 at various midpoints along their length between two corresponding coils 144. In some embodiments, the windings 142 (i.e., the wire ends or other portions of the wire 143) are soldered, resistance welded, or reflowed to the bracket 162. The phase connection portions 164 are connected to the corresponding phase wires 168 (corresponding to phases U, V, and W, for example), e.g. B. by soldering, resistance welding or melting.In the illustrated embodiment, each phase connection portion 164 defines a recess that receives one end of the corresponding phase wire 168, which is connected to the phase connection portion 164 by soldering. The terminals 148 thus electrically connect the phase wires 168 to the coils 144 to supply power thereto. The stator coils 144 are selectively energized by the power source 122, for example, via the FETs 124. In the illustrated embodiment, the stator coils 144 have three phases (e.g., phases U, V, and W). The three phases of the stator coils 144 may be connected together in a delta, star, or other suitable configuration.

[0021] The windings 142l further include transition sections 170 that extend circumferentially around portions of the insulator 136. In particular, the transition sections 170 are routed around portions of the first end cap portion 152 of the insulator 136. In the illustrated embodiment, the transition sections 170 extend to electrically connect at least two different coils 144 that are geometrically opposite each other with respect to the longitudinal axis 158. Other transition sections 170 also extend to connect between a corresponding coil 144 and a remotely located corresponding terminal 148. The transition sections 170 facilitate the winding configuration of the stator 112 (e.g., delta, star, or other suitable configurations). In particular, in the illustrated embodiment, the transition sections 170, like the terminals 148, are arranged at the first axial end 150 of the motor 101.

[0022] As in Fig. 4C, the motor 101 further includes a printed circuit board assembly (LPA) 172 coupled to the stator 112 at the first axial end 150. The LPA carries the Hall effect sensors 128 ( Fig. 3). The LPA 172 includes a central ring 174 defining a central through-hole 176 and a plurality of arms 178 projecting radially outward from the central ring 174. The arms 178 are attached to the first end cap portion 152 of the insulator 136. In particular, the first end cap portion 152 includes a plurality of mounting portions 180 projecting axially outward, the number of which corresponds to the arms 178. In the illustrated embodiment, each arm 178 is attached to the corresponding mounting portion 180 via a screw. In other embodiments, the arms 178 may be connected to the mounting portions 180 via alternative means, as discussed below.

[0023] Fig. 5 shows a hot riveting process for attaching the arms 178 to the mounting portions 180 of the first end cap portion 152 according to another embodiment. During the hot riveting process, an axially projecting shaft or mandrel 182 extending from the mounting portion 180 of the insulator 136 is pressed into a recess formed in the arm 178 of the LPA 172. The mandrel 182 is formed with an axial length greater than an axial length of the recess, i.e., greater than a width of the arm 178, such that an end portion of the mandrel 182 protrudes beyond an edge of the recess. The end portion of the mandrel 182 is then heated until it is partially melted, forming a cap or rivet over the edge of the recess. This ensures a secure mechanical connection between the insulator 136 and the LPA 172.

[0024] Fig. 6A-6D show an embodiment of a motor 201 similar to the motor 101 described above, wherein similar illustrated features are represented by similar reference numerals plus "100," except as otherwise explained below. The motor 201 includes a stator 212 that is substantially similar to the stator 112 described above, except for the differences described below. The stator 212 is connected to the motor 101 described above with respect to Fig. 2, so that the motor 201 can have the rotor 114. The motor 201 can equally be used in the power tool 100 described above ( Fig. 1 and Fig. 2) and is also connected to the power source 122, the FETs 124, the Hall effect sensors 128, the motor controller 130, the user input 132 and the other components mentioned above with respect to Fig. 3 described components 133 operable.

[0025] The stator 212 includes a core 234, an insulator 236, windings 242, and a terminal assembly 246. The core 234 includes a yoke 238 and a plurality of teeth 240. The windings 242 are wound around the teeth 240 to form coils 244. In some embodiments, the windings 242 may be formed entirely from a single insulated wire 243 wound around the teeth 240 to form all of the coils 244. The insulator 236 includes a first end cap portion 252 disposed at the first axial end 250 of the motor 201 and a second end cap portion 254 disposed at an opposite second axial end 256.

[0026] As with regard to Fig. 6C-6D, the terminal assembly 246 includes a plurality of terminals 248 for electrically connecting the coils 244 in a winding arrangement. The terminals 248 are substantially similar to the terminals 148 described above and are carried by the first end cap portion 252 in a similar manner and arrangement as described for the motor 101. In particular, each terminal 248 includes a main body portion 260, a winding connecting portion or bracket 262, and a phase connecting portion 264. The phase connecting portion 264 defines a recess 265 that receives one end of the corresponding phase wire (not shown, but see the Fig. 4E). However, the main body portion 260 has a shorter axial length than the main body portion 160 of the terminal 148. In other words, the main body portion 260 has a shorter length in an axial direction of the motor 201, or in a direction of the longitudinal axis 258, than the main body portion 160 described above.

[0027] The windings 242 further include transition sections 270 that extend circumferentially around a portion of the insulator 236. As shown in Fig. 6C, some of the transition sections 270 are routed around portions of the first end cap section 252 to connect at least some of the coils 244 to the terminals 248. As shown in Fig. 6B, some of the transition sections 270 extend around portions of the second end cap portion 254 (i.e., at the second axial end 256) to electrically connect at least two different coils 244 that are geometrically opposite each other with respect to the longitudinal axis 258. The transition sections 270 facilitate the winding configuration of the stator 212 (e.g., delta, star, or other suitable configurations). Because at least some of the transition sections 270 are disposed at the second axial end 256 of the motor 201 in the illustrated embodiment, relatively fewer transition sections 270 are disposed at the first axial end 250 compared to the motor 101. Therefore, relatively less space is required to accommodate the transition sections 270 at the first axial end 250.This arrangement of the transition sections 270 enables a shortening of the length of the main body sections 260 of the terminals 248, as described above, generally resulting in a smaller overall axial length of the motor 201 compared to the motor 101. The shorter length of the motor 201 is advantageous because, for example, the motor 201 will occupy relatively less space in the motor housing section 106 of the power tool 100, and the size of the power tool 100 can be reduced accordingly.

[0028] As mentioned with reference to Fig. 6C, the motor 201 also includes mounting sections 280 for coupling the LPA 172 ( Fig. 4C) with the stator 212. The mounting sections 280 differ from the mounting sections 180 described here ( Fig. 4C), since the mounting sections 280 comprise axially projecting mandrels 282 for fastening the LPA 172 to the stator 212 by hot riveting (see Fig. 5 and corresponding description). Since the LPA 172 is hot-riveted to the mounting sections 280, the mounting sections 280 do not have threaded holes for receiving screws, which reduces an axial length of the mounting sections 280 compared to the mounting sections 180. This means that an overall axial length of the motor 201 is further reduced compared to the motor 101.

[0029] Fig. 7A-7F show an embodiment of a motor 301 similar to the motor 101 described above, wherein similar illustrated features are represented by similar reference numerals plus "200," except as otherwise explained below. The motor 301 includes a stator 312 that is substantially similar to the stator 112 described above, except for the differences described below. The stator 312 is connected to the motor 101 described above with respect to Fig. 2, so that the motor 301 can have the rotor 114. The motor 301 can equally be used in the power tool 100 described above ( Fig. 1 and Fig. 2) and is also connected to the power source 122, the FETs 124, the Hall effect sensors 128, the motor controller 130, the user input 132 and the other components mentioned above with respect to Fig. 3 described components 133 operable.

[0030] As mentioned with reference to Fig. 7A-7D, the stator 312 includes a core 334, an insulator 336, windings 342, and a terminal assembly 346. The core 334 includes a yoke 338 and a plurality of teeth 340. The windings 342 are wound around the teeth 340 to form coils 344. In some embodiments, the windings 342 may be formed entirely from a single insulated wire (not shown) that is wound around the teeth 340 to form all of the coils 344, or in other embodiments, the windings 342 may include two or more separate wires forming the coils 344. The insulator 336 includes a first end cap portion 352 disposed at the first axial end 350 of the motor 301 and a second end cap portion 354 disposed at an opposite second axial end 356.

[0031] As with regard to Fig. 7C-7E, the terminal assembly 346 includes a plurality of terminals 348, including some phase connection terminals 348A and some winding connection terminals 348B, for electrically connecting the coils 344 in a winding assembly. The terminals 348A are similar to the terminals 148 described above and are carried by the first end cap portion 352. In the illustrated embodiment, there are six terminals 348A. Specifically, each terminal 348A includes a main body portion 360, a winding connection portion or bracket 362, and a phase connection portion 364. The phase connection portion 364 is somewhat different from the phase connection portion 164 described herein and is not directly connected to a phase wire (not shown, but see the phase wire 168 in Fig. 4E). The phase connection portion 364 is instead connected to an LPA 384, as discussed further. The terminals 348B are also similar to the terminals 148 described above and are carried by the first end cap portion 352, but the terminals 348B do not include a phase connection portion. In the illustrated embodiment, there are three terminals 348B. The terminals 348B only form connections between different coils 344 and are not directly connected to the phase wires.

[0032] The LPA 384 differs from the LPA 172 described above and serves to connect the coils 344 to the phase wires. And the LPA 384, in at least some embodiments, carries the Hall-effect sensors 128 ( Fig. 3). The LPA 384 includes a central ring 374 defining a central through-hole 376 and a plurality of arms 378 extending radially outward from the central ring 374. In the illustrated embodiment, the LPA 384 includes six arms 378, each arm 378 corresponding to a phase connection portion 364 of the corresponding terminal 348A. Each arm 378 defines a notch 386 at its distal end that receives the phase connection portion 364 of the corresponding terminal 348A, which is then soldered to the LPA 384 (e.g., to a conductive pad disposed at the notch 386). The LPA 384 further includes conductive traces (not shown) that electrically connect the terminals 348A to the phase wires to form the particular winding configuration of the stator 312 (e.g., delta, star, or other suitable configurations).That is, the phase wires (not shown) are connected to the LPA 384 rather than to the terminals 348. Thus, the motor 301 includes no (or relatively fewer) transition sections, allowing the overall length of the motor 301 to be shortened compared to the motor 101.

[0033] As mentioned with reference to Fig. 7C and Fig. 7F, the motor 301 also includes mounting sections 380 for coupling the LPA 384 to the stator 312. The mounting sections 380 differ from the mounting sections 180 described here ( Fig. 4C), since the mounting portions 380 are arranged on radially inner portions of the teeth 340. The mounting portions 380 include axially projecting mandrels 382 for attaching the LPA 384 to the stator 312 by hot riveting (see Fig. 5 and corresponding description). The central ring 374 of the LPA 384 includes a plurality of recesses 388 that correspond to and receive the mandrels 382. Because the LPA 384 is hot-riveted to the mounting portions 380, the mounting portions 380 do not have threaded holes for receiving screws, which reduces an axial length of the mounting portions 380 compared to the mounting portions 180. This means that an overall axial length of the motor 301 is further reduced compared to the motor 101.

[0034] Fig. Figure 8 shows an embodiment of a motor 401 similar to the motor 301 described above, wherein similar illustrated features are represented by similar reference numerals plus "100", except as otherwise explained below. The motor 401 includes a stator 412 that is substantially similar to the stator 312 described above, except for the differences described below. The stator 412 is connected to the motor 401 described above with respect to Fig. 2, so that the motor 401 can have the rotor 114. The motor 401 can equally be used in the power tool 100 described above ( Fig. 1 and Fig. 2) and is also connected to the power source 122, the FETs 124, the Hall effect sensors 128, the motor controller 130, the user input 132 and the other components mentioned above with respect to Fig. 3 described components 133 operable.

[0035] The stator 412 includes a core 434, an insulator 436, windings (not shown), and a terminal assembly 446. The core 434 includes a yoke 438 and a plurality of teeth 440. The windings are wound around the teeth 440 to form coils (not shown). In some embodiments, the windings may be formed entirely from a single insulated wire wound around the teeth 440 to form all of the coils, or in other embodiments, the windings may comprise two or more separate wires forming the coils. The insulator 436 includes a first end cap portion 452 disposed at the first axial end 450 of the motor 401 and a second end cap portion 454 disposed at an opposite second axial end 456.

[0036] The terminal assembly 446 includes a plurality of terminals 448, all of which are phase connection terminals, for electrically connecting the coils in a winding assembly. The terminals 448 are similar to the terminals 348A described above and are carried by the first end cap portion 452. In the illustrated embodiment, there are six terminals 448. Specifically, each terminal 448 includes a main body portion 460, a winding connection portion or bracket 462, and a phase connection portion 464. The phase connection portion 464 is connected to an LPA 484, as discussed further.

[0037] The LPA 484 serves to connect the coils to the phase wires. And the LPA 484 carries, in at least some embodiments, the Hall-effect sensors 128 ( Fig. 3). The LPA 484 is generally circular and shaped like a flat disk and defines a central through-hole 476. The LPA 484, in the illustrated embodiment, includes six spaced-apart notches 490 in its radially outer periphery, each receiving a corresponding main body portion 460 of a corresponding terminal 448. The LPA 484 also includes six through-holes 492, each through-hole 492 being located adjacent a corresponding first notch 490. The through-holes 492 correspond to the phase connection portion 464 of the terminal 448. Each through-hole 492 receives the phase connection portion 464 of the corresponding terminal 448, which is then soldered to the LPA 484 (e.g., to a conductive pad disposed at the through-hole 492).The LPA 484 further includes conductive traces (not shown) that electrically connect the terminals 448 to the phase wires to form the particular winding configuration of the stator 412 (e.g., delta, star, or other suitable configurations). That is, the phase wires (not shown) are connected to the LPA 484 rather than to the actual terminals 448. The motor 401 thus includes no (or relatively fewer) transition sections, allowing the overall length of the motor 401 to be shortened compared to the motor 101.

[0038] The motor 401 also includes mounting sections 480 for coupling the LPA 484 to the stator 412. The mounting sections 480 are located on the first end cap section 452 and include axially projecting mandrels 482 for attaching the LPA 484 to the stator 412 by hot riveting (see Fig.5 and corresponding description). The LPA 484 includes a plurality of recesses 488 that correspond to and receive the mandrels 482. Because the LPA 484 is hot-riveted to the mounting portions 480, the mounting portions 480 do not have threaded holes for receiving screws, which reduces an axial length of the mounting portions 480 compared to the mounting portions 180. That is, an overall axial length of the motor 401 is further reduced compared to the motor 101.

[0039] Although the disclosure has been described in detail with reference to certain preferred embodiments, variations and modifications are within the scope and spirit of one or more independent aspects of the described disclosure. Various features and / or advantages of the disclosure are set forth in the following claims.

Claims

[1] Power tool comprising: a housing having a motor housing portion and a handle portion; an electric motor mounted in the motor housing portion and having a rotor and a stator, the rotor being coupled to a motor shaft, the motor shaft having a spindle portion carrying an output unit; where the stator comprises: a core, an insulator coupled to the core and having an end cap portion positioned at an axial end of the stator, a winding forming a coil, and a terminal configured to electrically connect the winding to a power source, the terminal being supported by the end cap portion and comprising a main body portion, a bracket, and a phase connection portion; wherein the main body portion of the terminal is in contact with the end cap portion and is generally planar and extends away from the end cap portion in an axial direction of the electric motor; wherein the bracket extends away from the main body portion in a radial direction of the electric motor and is bent toward the axial direction, the bracket being designed for mechanical and electrical connection to the winding; and wherein the phase connection portion extends away from the main body portion in a circumferential direction perpendicular to the axial direction, the phase connection portion being configured for mechanical and electrical connection to a phase wire configured for supplying power from the power source. [2] The power tool of claim 1, wherein the phase connecting portion is generally planar and forms an obtuse angle with the main body portion. [3] Power tool according to claim 2, wherein the obtuse angle is between 110 degrees and 170 degrees. [4] The power tool of claim 1, wherein the phase connecting portion defines a recess configured to receive a wire end of the phase wire. [5] Power tool according to claim 1, wherein: the coil is a first coil and the stator further comprises a second coil arranged opposite the first coil with respect to a longitudinal axis of the electric motor; and the winding comprises an elongated wire wound around the insulator to form both the first coil and the second coil, the elongated wire further forming a transition portion extending around at least a portion of a circumference of the end cap portion to electrically connect the first coil to the second coil. [6] Power tool according to claim 5, wherein the transition section is arranged at the axial end of the stator. [7] Power tool according to claim 5, wherein: the axial end of the stator is a first axial end and the end cap portion is a first end cap portion; the insulator further comprises a second end cap portion positioned at a second axial end of the stator and disposed opposite the first axial end; and the transition section is arranged at the second axial end. [8] The power tool of claim 1, wherein the electric motor further comprises a printed circuit board assembly (LPA), and wherein the end cap portion includes a mandrel extending axially through a recess defined in the LPA, the mandrel being configured to secure the LPA to the end cap portion. [9] Power tool comprising: a housing having a motor housing portion and a handle portion; an electric motor mounted in the motor housing portion and having a rotor and a stator, the rotor coupled to a motor shaft; where the stator comprises: a core, an insulator coupled to the core and having a first end cap portion positioned at a first axial end of the stator and a second end cap portion disposed at a second axial end of the stator opposite the first axial end, a winding forming a first coil and a second coil, and a terminal configured to electrically connect the winding to a power source, the terminal being supported by the first end cap portion and comprising a main body portion, a bracket, and a phase connection portion; wherein the main body portion is in contact with the first end cap portion and is generally planar and extends away from the first end cap portion in an axial direction of the electric motor; wherein the bracket extends away from the main body portion in a radial direction of the electric motor and is bent toward the axial direction, the bracket being designed for mechanical and electrical connection to the winding; and wherein the winding comprises an elongated wire wound around the insulator to form both the first coil and the second coil, the elongated wire further forming a transition portion extending at the second axial end around at least a portion of a circumference of the second end cap portion to electrically connect the first coil to the second coil. [10] The power tool according to claim 9, wherein the phase connecting portion extends away from the main body portion in a circumferential direction perpendicular to the axial direction, the phase connecting portion being adapted for mechanical and electrical connection to a phase wire adapted for supplying power from the power source. [11] The power tool of claim 10, wherein the phase connecting portion is generally planar and forms an obtuse angle with the main body portion. [12] Power tool according to claim 11, wherein the obtuse angle is between 110 degrees and 170 degrees. [13] The power tool of claim 9, wherein the electric motor further comprises a printed circuit board assembly (LPA), and wherein the first end cap portion includes a mandrel extending axially through a recess defined in the LPA, the mandrel being configured to secure the LPA to the first end cap portion. [14] Power tool comprising: a housing having a motor housing portion and a handle portion; an electric motor mounted in the motor housing portion and having a stator, a rotor coupled to a motor shaft, and a printed circuit board assembly (LPA); where the stator comprises: a core, an insulator coupled to the core and having an end cap portion positioned at an axial end of the stator, a winding forming a coil, and a terminal configured to electrically connect the winding to a power source, the terminal being supported by the end cap portion and comprising a main body portion, a bracket, and a phase connection portion; wherein the main body portion of the terminal is in contact with the end cap portion and is generally planar and extends away from the end cap portion in an axial direction of the electric motor; wherein the bracket extends away from the main body portion in a radial direction of the electric motor and is bent toward the axial direction, the bracket being designed for mechanical and electrical connection to the winding; and wherein the phase connection portion extends away from the main body portion in a circumferential direction perpendicular to the axial direction, the phase connection portion being adapted for mechanical and electrical connection to the LPA. [15] The power tool of claim 14, wherein the coil is a first coil and the stator further comprises a second coil, and wherein the LPA electrically connects the first coil to the second coil. [16] The power tool of claim 15, wherein the LPA includes a central ring and an arm extending radially outwardly from the central ring, and wherein the arm defines a connection notch that receives the phase connection portion. [17] The power tool of claim 16, wherein the LPA defines a terminal notch that receives the main body portion. [18] The power tool of claim 15, wherein the end cap portion includes a mandrel axially extending through a recess defined in the LPA, the mandrel being configured to secure the LPA to the end cap portion. [19] The power tool of claim 15, wherein the LPA comprises a Hall effect sensor.

Images