Electric tool

Abstract

The utility model provides an electric tool which comprises a machine shell, a motor assembly contained in the machine shell and an end assembly driven by the motor assembly to operate, the machine shell is provided with an air suction port and an air exhaust port which are arranged at intervals, and the motor assembly comprises a stator and a motor rotor structure connected to the stator. The motor rotor structure comprises a rotor shaft, a second fan installed at the end of the rotor shaft, an iron core arranged on the rotor shaft in a sleeving mode and an intermediate shaft arranged between the rotor shaft and the iron core, the iron core is fixed to the rotor shaft through the intermediate shaft, the fan rotates to generate cooling airflow, and the cooling airflow is sucked in from an air suction port, flows through a motor assembly and is exhausted from an exhaust port. A second insulating part is arranged at the end, away from the second fan, of the middle shaft and integrally connected with a first fan, the first fan and the middle shaft are of an integrated structure, and the first fan is located on the downstream of the air suction port.

Description

Technical Field

[0001] This utility model relates to the field of power tool technology, and in particular to a motor rotor structure. Background Technology

[0002] Brushless motors, as small and highly efficient motors, are widely used in the power tool industry. A brushless motor consists of a stator and a rotor. Because the rotor contains magnets, it possesses its own magnetic field, which easily attracts metal dust such as iron powder. This metal dust is difficult to expel with airflow, and its presence can affect the normal operation of the brushless motor. Therefore, a small fan is usually installed at the rear end of the rotor for dust removal. As the fan rotates with the rotor, it throws the metal dust towards the outside of the stator, ensuring clean, cool airflow around the rotor.

[0003] However, since the small fan requires additional pressing, the installation is not only cumbersome, but the small fan may also become skewed during the pressing process, thereby increasing the rotor imbalance and affecting the normal operation of the rotor. Utility Model Content

[0004] The purpose of this utility model is to provide an electric tool with a motor rotor structure that eliminates the need for separate installation of the first fan, thereby simplifying the installation process, improving installation efficiency, and preventing the first fan from being misaligned, thus avoiding an increase in rotor imbalance.

[0005] This utility model provides a motor rotor structure, including a housing, a motor assembly housed in the housing, and an end assembly driven by the motor assembly. The housing has an air intake and an exhaust port spaced apart. The motor assembly includes a stator and a motor rotor structure connected to the stator. The motor rotor structure includes a rotor shaft, a second fan mounted on one side of the rotor shaft, an iron core sleeved on the rotor shaft, and an intermediate shaft disposed between the rotor shaft and the iron core. The iron core is fixed to the rotor shaft via the intermediate shaft. The fan rotates to generate a cooling airflow, which is drawn in from the air intake, flows through the motor assembly, and exits from the exhaust port. The key feature is that a second insulating member is provided at the end of the intermediate shaft away from the second fan. The second insulating member is integrally connected to a first fan, and the first fan and the intermediate shaft are an integral structure. The first fan is located downstream of the air intake.

[0006] In one possible implementation, the intermediate shaft is formed by injection molding resin material between the rotor shaft and the iron core, and the first fan is integrally injection molded with the intermediate shaft.

[0007] In one possible implementation, the intermediate shaft has a first insulating element at its end near the second fan, and the iron core is located between the first insulating element and the second insulating element.

[0008] In one feasible embodiment, the first insulating element and the second insulating element are integrally formed with the intermediate shaft.

[0009] In one possible implementation, the core has a plurality of circumferentially arranged mounting slots, the mounting slots being provided with magnets.

[0010] In one possible implementation, the first fan includes a plurality of blades circumferentially spaced along the intermediate shaft, the blades extending radially outward from the outer wall of the intermediate shaft; each blade is integrally connected to the second insulator, and the outer edge of each blade is flush with the outer wall of the second insulator.

[0011] In one possible implementation, a second fan is fitted and fixed onto the rotor shaft, the second fan having a larger radial dimension than the first fan.

[0012] In one possible implementation, the outer wall of the rotor shaft is provided with a mounting portion and a stop portion spaced axially, the mounting portion and the stop portion being located on opposite sides of the intermediate shaft, and the opposite ends of the intermediate shaft abutting against the mounting portion and the stop portion respectively; the second fan is sleeved and fixed on the mounting portion.

[0013] In one possible implementation, the second fan has a central hole, and the mounting part is inserted into the central hole; the outer wall of the mounting part has a first keyway structure, and the inner wall of the central hole has a second keyway structure, the first keyway structure and the second keyway structure engaging with each other, thereby fixing the second fan and the mounting part in the circumferential direction of the rotor shaft.

[0014] In one feasible implementation, the motor assembly is a brushless motor.

[0015] The power tool provided by this utility model has a first fan integrally formed on the intermediate shaft of the motor rotor structure, so there is no need to install the first fan separately, which simplifies the installation steps and improves the installation efficiency. Moreover, the first fan does not require additional mold opening and tooling design, thereby saving material and mold costs. At the same time, it can avoid the first fan's installation position from being skewed, thereby avoiding increasing the rotor's imbalance and ensuring the rotor's stable operation. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of the motor rotor structure in an embodiment of this utility model.

[0017] Figure 2 for Figure 1 The main view.

[0018] Figure 3 for Figure 1 A schematic diagram of the explosion structure.

[0019] Figure 4 The embodiments of this utility model have Figure 1 A three-dimensional structural diagram of the power tool with the described motor rotor structure. Detailed Implementation

[0020] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit its scope.

[0021] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and claims of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0022] like Figures 1 to 3 As shown in the figure, the motor rotor structure provided in this embodiment of the present invention is applied to a motor assembly, which is a brushless motor. The motor rotor structure includes a rotor shaft 1, an iron core 3 sleeved outside the rotor shaft 1, and an intermediate shaft 2 disposed between the rotor shaft 1 and the iron core 3. The iron core 3 is fixed to the rotor shaft 1 via the intermediate shaft 2. Specifically, both the intermediate shaft 2 and the iron core 3 are hollow cylindrical structures. Both the intermediate shaft 2 and the iron core 3 extend axially along the rotor shaft 1. The intermediate shaft 2 is sleeved and fixed outside the rotor shaft 1, and the opposite ends of the rotor shaft 1 extend to the opposite sides of the intermediate shaft 2. The iron core 3 is sleeved and fixed outside the intermediate shaft 2. The axes of the rotor shaft 1, the intermediate shaft 2, and the iron core 3 coincide or substantially coincide. A magnet 4 is provided inside the iron core 3, which can specifically be a magnet, a magnetic steel, etc. A first fan 21 is provided at one end of the intermediate shaft 2. The first fan 21 and the intermediate shaft 2 are integrally formed, meaning that the first fan 21 and the intermediate shaft 2 are integrally molded. The first fan 21 is formed by extending radially outward from the outer wall of the intermediate shaft 2 and is located on one side of the iron core 3 along its axial direction. The first fan 21 is used for dust removal; when the motor rotor structure rotates, the first fan 21 rotates along with the intermediate shaft 2. The first fan 21 can act like a centrifugal fan, throwing off the metal dust adsorbed on the rotor, thereby preventing the metal dust from affecting the normal operation of the rotor.

[0023] The motor rotor structure provided in this embodiment integrates the first fan 21 onto the intermediate shaft 2, thus eliminating the need for separate installation of the first fan 21, simplifying the installation process, improving installation efficiency, and saving material and mold costs by eliminating the need for additional mold opening and tooling design for the first fan 21. At the same time, it can prevent the installation position of the first fan 21 from being skewed, thereby avoiding an increase in the rotor imbalance and ensuring stable rotor operation.

[0024] In one embodiment, the intermediate shaft 2 is made of insulating material, specifically plastic, to insulate the rotor shaft 1 and the iron core 3 (the rotor shaft 1 is generally made of metal). In another embodiment, the intermediate shaft 2 is formed by injection molding resin material between the rotor shaft 1 and the iron core 3. The first fan 21 and the intermediate shaft 2 are integrally molded by injection molding. This resin material can be BMC (bulk molding compound) resin, etc. During the fabrication of the intermediate shaft 2, the iron core 3, on which the magnet 4 is mounted, is fitted over the rotor shaft 1, with a gap between the iron core 3 and the rotor shaft 1. Molten resin material is injected into the iron core 3 and the rotor shaft 1 using an injection molding process, filling the gap between the iron core 3 and the rotor shaft 1. After cooling, the intermediate shaft 2 with the first fan 21 is obtained. The intermediate shaft 2 can be tightly connected to the iron core 3 and the rotor shaft 1, thereby fixing the iron core 3 and the rotor shaft 1.

[0025] like Figures 1 to 3 As shown, in one embodiment, the intermediate shaft 2 has a first insulating member 22 and a second insulating member 23 at its opposite ends, and the iron core 3 is located between the first insulating member 22 and the second insulating member 23. The opposite ends of the iron core 3 abut against the first insulating member 22 and the second insulating member 23, respectively. The first insulating member 22 is located on the side of the iron core 3 away from the first fan 21, and the second insulating member 23 is located between the iron core 3 and the first fan 21. Both the first insulating member 22 and the second insulating member 23 are annular structures. The first insulating member 22 and the second insulating member 23 are used to ensure the weight balance on both sides of the iron core 3, thereby maintaining the dynamic balance of the rotor.

[0026] In this embodiment, the first insulating component 22 and the second insulating component 23 are integrally formed with the intermediate shaft 2, i.e., they are integrally molded together by injection molding. The first insulating component 22 and the second insulating component 23 are formed by extending radially outward from the outer wall of the intermediate shaft 2, and both are made of resin. This not only facilitates the processing and molding of the first insulating component 22 and the second insulating component 23 without the need for additional insulating components, but also makes the resin-based first insulating component 22 and the second insulating component 23 less expensive than materials such as copper, thus saving costs. Furthermore, the production cost of processing resin is lower, and when the rotor has dynamic balance errors, the balance can be adjusted by cutting and removing weight from the insulating components. Of course, in other embodiments, the first insulating component 22 and the second insulating component 23 can also be separate structures from the intermediate shaft 2, for example, by press-fitting them onto the intermediate shaft 2.

[0027] In this embodiment, the second insulating member 23 is disposed adjacent to the first fan 21, and the second insulating member 23 is integrally connected to the first fan 21. Specifically, the first fan 21 includes a plurality of blades 211 arranged circumferentially along the intermediate shaft 2. The blades 211 extend radially outward from the outer wall of the intermediate shaft 2. Each blade 211 is integrally connected to the second insulating member 23, and the outer edge of each blade 211 (i.e., the edge of the blade 211 away from the intermediate shaft 2) is flush with the outer wall of the second insulating member 23. This not only ensures that the first fan 21 has a good dust removal effect, but also improves the structural strength of the first fan 21, and makes the structure of the entire intermediate shaft 2 more compact.

[0028] like Figures 1 to 3 As shown, in one embodiment, a second fan 5 is fixedly mounted on the rotor shaft 1. The outer diameter of the second fan 5 is larger than that of the first fan 21 (i.e., the second fan 5 is a large fan, and the first fan 21 is a small fan). The second fan 5 is located on the side of the intermediate shaft 2 away from the first fan 21. When the motor rotor structure rotates, the second fan 5 rotates along with the rotor shaft 1, causing airflow to generate cool air, thereby cooling the brushless motor. Specifically, in this embodiment, the second fan 5 has a central hole 51 located at the center of the second fan 5. The rotor shaft 1 is inserted into the central hole 51, and the outer wall of the rotor shaft 1 is fixed to the inner wall of the central hole 51.

[0029] like Figures 1 to 3As shown, in one embodiment, a mounting portion 11 and a stop portion 12 are axially spaced on the outer wall of the rotor shaft 1. The mounting portion 11 and the stop portion 12 are located on opposite sides of the intermediate shaft 2, and the opposite ends of the intermediate shaft 2 abut against the mounting portion 11 and the stop portion 12, thereby limiting the intermediate shaft 2. The second fan 5 is sleeved and fixed on the mounting portion 11, which is inserted into the central hole 51, and the outer wall of the mounting portion 11 is fixed to the inner wall of the central hole 51. In this embodiment, the mounting portion 11 and the stop portion 12 are integral with the rotor shaft 1, and are formed by the radially outward extension of the outer wall of the rotor shaft 1. Of course, in other embodiments, the mounting portion 11 and the stop portion 12 can also be separate from the rotor shaft 1, and can be fixed to the outer wall of the rotor shaft 1 by press fitting.

[0030] Specifically, in this embodiment, a first keyway structure 111 is provided on the outer wall of the mounting part 11, and a second keyway structure (not shown) is provided on the inner wall of the central hole 51. The first keyway structure 111 and the second keyway structure engage with each other, thereby fixing the second fan 5 and the mounting part 11 together in the circumferential direction of the rotor shaft 1. One of the first keyway structure 111 and the second keyway structure includes one or more grooves, and the other includes one or more key teeth that engage with the grooves. This keyway structure facilitates the assembly of the second fan 5 and the mounting part 11.

[0031] like Figure 3 As shown, in one embodiment, the iron core 3 contains a plurality of magnets 4 (the figure shows four magnets 4, i.e., the motor has four magnetic poles. Of course, in other embodiments, the number of magnets 4 can be different depending on the number of magnetic poles of the motor). The plurality of magnets 4 are arranged at intervals along the circumference of the iron core 3, and each magnet 4 extends along the axial direction of the iron core 3 to form a long strip-shaped block structure. In this embodiment, the iron core 3 contains a plurality of mounting slots 31, and the plurality of magnets 4 are respectively disposed in the plurality of mounting slots 31; the axial end face of the iron core 3 has an opening (not labeled in the figure) communicating with the mounting slots 31, through which the magnets 4 can be installed into the mounting slots 31.

[0032] This utility model embodiment also provides a motor assembly, which is a brushless motor, including a stator (not shown) and a motor rotor structure as described above, wherein the motor stator is arranged around the outer periphery of the motor rotor structure. For details regarding the specific structure of the motor stator and the fit between the motor stator and the motor rotor structure, please refer to the prior art, which will not be elaborated here.

[0033] This utility model embodiment also provides an electric tool 100, including a housing 100a, a brushless motor as described above, and an end assembly driven by the brushless motor. The electric tool 100 can be a drill, electric wrench, angle grinder, cutter, etc., preferably an angle grinder. When the electric tool 100 is operating, the second fan 5 operates, thereby drawing in cooling airflow from outside the housing 100a through the intake port 100b on the housing 100a, allowing the cooling airflow to flow through the motor assembly, and finally dissipating the cooling airflow from the exhaust port 100c, achieving a cooling effect. It is worth noting that the exhaust port 100c must be spaced apart from the intake port 100b, and the iron core 3 in the motor rotor structure is located downstream of the intake port 100b.

[0034] The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. An electric tool, comprising a housing, a motor assembly housed within the housing, and an end assembly driven by the motor assembly, the housing having an air intake and an exhaust port spaced apart, the motor assembly comprising a stator and a motor rotor structure connected to the stator, the motor rotor structure comprising a rotor shaft, a second fan mounted on one side of the rotor shaft, an iron core sleeved on the rotor shaft, and an intermediate shaft disposed between the rotor shaft and the iron core, the iron core being fixed to the rotor shaft via the intermediate shaft, the fan rotating to generate a cooling airflow, the cooling airflow being drawn in from the air intake, flowing through the motor assembly, and exiting from the exhaust port; characterized in that: The intermediate shaft has a second insulating component at the end away from the second fan. The second insulating component is integrally connected to the first fan. The first fan and the intermediate shaft are an integral structure. The first fan is located downstream of the air intake.

2. The power tool as described in claim 1, characterized in that, The intermediate shaft is formed by injection molding resin material between the rotor shaft and the iron core, and the first fan and the intermediate shaft are integrally injection molded.

3. The power tool as described in claim 1, characterized in that, The intermediate shaft is provided with a first insulating element at the end near the second fan, and the iron core is located between the first insulating element and the second insulating element.

4. The power tool as described in claim 3, characterized in that, The first insulating component and the second insulating component are integral with the intermediate shaft.

5. The power tool as described in claim 4, characterized in that, The iron core has multiple mounting slots arranged circumferentially, and the mounting slots are equipped with magnets.

6. The power tool as described in claim 5, characterized in that, The first fan includes a plurality of blades circumferentially spaced along the intermediate shaft, the blades extending radially outward from the outer wall of the intermediate shaft; each blade is integrally connected to the second insulating member, and the outer edge of each blade is flush with the outer wall of the second insulating member.

7. The power tool as claimed in any one of claims 1-6, characterized in that, A second fan is fixedly mounted on the rotor shaft, and the second fan has a larger radial dimension than the first fan.

8. The power tool as claimed in claim 7, characterized in that, The outer wall of the rotor shaft is provided with a mounting part and a stop part spaced apart along the axial direction. The mounting part and the stop part are respectively located on opposite sides of the intermediate shaft, and the opposite ends of the intermediate shaft abut against the mounting part and the stop part respectively. The second fan is sleeved and fixed on the mounting part.

9. The power tool as claimed in claim 8, characterized in that, The second fan has a central hole, and the mounting part is inserted into the central hole; the outer wall of the mounting part has a first keyway structure, and the inner wall of the central hole has a second keyway structure. The first keyway structure and the second keyway structure engage with each other, thereby fixing the second fan and the mounting part in the circumferential direction of the rotor shaft.

10. The power tool as claimed in claim 1, characterized in that, The motor assembly is a brushless motor.

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