TWI404595B - Improve the efficiency of the hand-held machine tool - Google Patents

Abstract

The present invention provides a hand-held machine tool for improving output efficiency. The hand-held machine tool has a casing accommodating a control circuit connected to a power source and an electric motor, wherein the control circuit determines the electric power conducted to the electric motor. The electric motor comprises a stator, a rotor and an output shaft. The stator has a core portion and a plurality of stator magnetic poles extended in a radial manner. The stator magnetic poles are wound with an exciting winding, and the core portion has a through shaft hole. The output shaft is penetrated through the shaft hole in a rotatable manner. The rotor has transmission portion fixed with the output shaft, and an induction portion which is extended from the transmission portion and has its horizontal projection position covering the induction portion of the stator magnetic poles. The inner edge of the induction portion has a plurality of rotor magnetic poles corresponding to the stator magnetic poles. The rotor magnetic poles may be magnetically coupled with the stator magnetic poles to induct a magnetic force for driving the output shaft rotating in the shaft hole relative to the stator.

Description

Hand-held power tool for improving output efficiency

A hand-held power tool for improving output efficiency, and more particularly to a motor structure in which a hand-held power tool has a high number of rotor poles.

Small machine tools (including pneumatic or electric) are popular due to their small size, low price and low energy consumption, and the machine tool includes a variety of variants such as grinders, drills, pneumatic (electric) wrenches, etc. A variety of types. The advantage of the electric machine tool is that the current of the electric motor can be precisely controlled through the circuit control, and the effect of controlling the number of revolutions can be achieved by further adjusting the magnitude or frequency of the current.

The most important purpose of the electric motor is to provide a force output shaft that connects the end tool element. Therefore, the horsepower and torque provided by the electric motor directly affect the performance of the machine tool. The design of the hand-held power tool considers the factors such as the volume and actual operation requirements. The selected electric motors are all high-speed motors, and then the design specifications of the hand-held machine tool can be met by adjusting the output characteristics of the motor or optionally adding a transmission gear set.

A hand-held power tool includes a housing for housing a motor, the motor including a casing, a stator 6 and a rotor (shown in US Patent Publication No. US 2010/0105287). Rotor 7). According to the disclosure of the specification, the rotor of the motor is located inside the stator, and the stator constitutes an internal rotation motor around the rotor. Due to the limited internal space of the motor, the number of magnetic poles provided by the rotor of the inner rotor motor is small. According to the electromagnetic principle, the motor with a low number of poles will produce a mechanical output with high rotational speed and low torque.

However, to improve the lack of low torque, the low-instant inner rotor motor output will cooperate with a gear set to provide higher torque at the extreme end through the number of teeth of the complex gears. The structure of the gear unit in combination with the electric motor can be found in the "Rechargeable Electric Grinding Tool" of the Republic of China Patent Publication No. 200932424, which discloses a rechargeable lithium battery pack, a touch switch and a drive motor in a housing of an electric grinding tool. . Wherein, the driving motor transmits an operating disk through a planetary reduction gear set, and the reduction gear is used to change the horsepower and torque of the final output to the operating plate. Although the horsepower and torsion of the output from the electric motor to the final output shaft can be changed through the gear set, there must be energy loss in the process of power conversion, and the more losses generated by the gears, the lower the efficiency of power consumption. Furthermore, the provision of the gear set also increases the assembly difficulty, the production cost, and takes up space in the machine tool housing. Moreover, the life of the gear also affects the service life of the hand-held power tool.

Therefore, there is a need to improve the problem of low power efficiency of the hand-held power tool.

Since the conventional hand-held power tool often uses the gear ratio deceleration principle to change the horsepower or torque between the motor end and the output end, the power loss during the operation of the gear set causes the power efficiency to be low. Therefore, the purpose of the present invention is to provide a hand-held power tool having better electrical efficiency.

The present invention is a hand-held power tool for improving output efficiency. The hand-held power tool has a casing including a control circuit for connecting a power source and an electric motor, wherein the control circuit determines the power level of the electric motor to be electrically connected to the electric motor. . The electric motor includes a stator, a rotor and a power output shaft, wherein the stator has a core and a plurality of stator poles radially extending from the core, and the stator poles are electrically connected to the control circuit. The field winding is wound and has a through shaft hole in the core. The output shaft is rotatable through the shaft hole. The rotor has a transmission portion fixedly coupled to the output shaft, and a sensing portion extending from the transmission portion and horizontally projecting the stator poles, the inner edge of the sensing portion having a plurality of rotor poles opposite to the stator poles The rotor pole is magnetically coupled to the stator pole to induce a magnetic force to drive the output shaft to rotate relative to the stator in the shaft bore.

More specifically, the number of rotor poles is 16 to 36, and the rotor poles are composed of magnets. At least one bearing is disposed in the shaft hole of the core for the output shaft to pass through to support stable rotation of the output shaft. The portion of the output shaft exposed to the shaft hole includes a tool connecting end for connecting a machining tool, and the output shaft is coupled to a blade group at an opposite end of the connecting tool. Since the sensing portion of the rotor is located outside the stator and covers the stator poles, the inner edge of the sensing portion has a large space for setting 16 to 36 rotor poles. Through the higher number of rotors, based on the principle of N = 120 F / P (speed = 120 x frequency / number of motor poles), the motor speed is reduced, and based on the principle of power conservation, the motor with the same output power reduces the motor rotor. The rotational speed relatively increases the torque of the rotor rotation. Therefore, the present invention provides a higher torque electric motor, so there is no need to pass through the gear set, which reduces the power loss and internal space of the gear set.

This case is a hand-held power tool that improves the output efficiency. The technical features of the present case will be described below in conjunction with the drawings.

Referring to FIG. 1 , FIG. 1 shows a structure of a hand-held power tool having a housing 1 including a control circuit 2 connected to a power source (not shown). The brushless electric motor 3, the control circuit 2 obtains an input power from the power source, and the control circuit 2 determines the amount of electric power that is conducted to the electric motor 3. The hand-held power tool will of course have an actuating mechanism for the user to operate. The operation of the actuating mechanism determines the amount of power that the control circuit 2 drives the electric motor 3. However, the actuating mechanism is easily accessible to those skilled in the art. The conventional structure of understanding is not shown in the drawings of the present case. Similarly, the control circuit 2 and the power source, and the wires connecting the control circuit 2 and the electric motor 3 are also common knowledge in the technical field, and are not drawn in the drawings. The electric motor 3 extends out of an output shaft 31. One end of the output shaft 31 is connected to a processing tool 5. The processing tool 5 can be a grinding disc or a wiping wheel or a rotary processing device commonly used in the art, and the output shaft 31 is transmitted through the output shaft 31. Rotating causes the processing tool 5 to perform the functions required by the operator. Moreover, one end of the output shaft 31 is connected to a blade group 4, the blade group 4 rotates with the output shaft 31, and the housing 1 includes a plurality of ventilation holes 10, and the rotation of the blade group 4 will The air is driven into or out of the vents 10 to dissipate the heat generated by the electric motor 3 and the control circuit 2 through the air flow. Further, the hand-held power tool is further provided with at least one heat dissipating component 6 which can be disposed in the casing 1 and can also be in contact with the control circuit 2 to enhance the heat dissipation effect.

Referring again to FIGS. 2, 3 and 4, FIG. 2 is an exploded view of the electric motor 3, wherein the electric motor 3 includes a stator 30 and a rotor 32 fixedly coupled to the output shaft 31. The stator 30 includes a core portion 301 and a plurality of stator poles 302 extending radially from the core portion 301. The stator poles 302 are wound with a field winding 303 electrically connected to the control circuit 2. The control circuit 2 provides power to the field winding 303 in response to user operation. The core portion 301 is provided with a through hole 306 (see FIG. 3). The output shaft 31 is rotatably passed through the shaft hole 306, and at least one bearing 304 is disposed in the shaft hole 306 for the output shaft 31 to pass through. The output shaft 31 is passed and supported. The core 301 extends from at least one bracket 305 to be coupled to the housing 1 such that the stator 30 is fixedly supported in a space within the housing 1. The output shaft 31 passes through the shaft hole 306 and exposes both ends of the output shaft 31 to the outside of the stator 30. One end of the output shaft 31 is connected to the processing tool 5, and the other end is fixedly connected to the rotor 32. The rotor 32 has a sensing portion 321 and a transmission portion 323. The transmission portion 323 includes a venting hole 324 and a nip portion 325 fixedly coupled to the output shaft 5, and the sensing portion 321 is coupled to the transmission portion 323 and The lower turn extends and the horizontal projection of the sensing portion 321 covers the stator poles 302. As is apparent from FIG. 3 and FIG. 4, the stator 30 is passed through the output shaft 31, and the transmission portion 323 of the rotor 32 extends horizontally from the output shaft 31, and after being extended for a length, the sensing portion 321 is formed, and The sensing portion 321 is extended downward, and the stator poles 302 are shrouded in the sensing portion 321 from the horizontal direction. The inner edge of the sensing portion 321 faces the stator magnetic poles 302, and the plurality of rotor magnetic poles 322 facing the stator magnetic poles 302 are disposed on the inner edge of the sensing portion 321 . The rotor poles 322 can be permanent magnets. After the control circuit 2 supplies power to the field winding 303, the stator pole 302 will generate magnetism, and the rotor pole 322 is magnetically coupled to the stator pole 302 to cause the rotor pole 322 to induce a magnetic force that drives the rotor 32 to rotate. The output shaft 31 is further rotated. The rotation of the output shaft 31 can drive the blade group 4 to generate airflow, and the electric motor 3 can also assist the airflow through the vent 324 to provide an excellent heat dissipation effect. Since the stator pole 302 is radially outwardly extended by the core 301, and the sensing portion 321 of the rotor 32 is covered outside the stator poles 302, the sensing portion 321 has a large circumference and can be arranged. The rotor pole 322 defines at least 16 rotor poles 322 on the sensing portion 321, and the number of rotor poles 322 is between 16 and 36. Preferably, the number of rotor poles 322 is 18 to 30. . In the structure disclosed in the present case, the number of rotor poles 322 is much larger than that of the conventional inner rotor type motor, and the rotor is reduced based on the calculation method of N = 120 F / P (rotation speed = 120 x frequency / number of motor poles) The rotational speed of 32 is based on the principle of power conservation. The motor with the same output power reduces the rotational speed of the rotor 32, and the torque of the rotation of the rotor 32 is relatively increased. Further, since the rotor 32 is located at the periphery of the stator 30, the linear distance of the rotor pole 322 of the sensing portion 321 to the output shaft 31 is much longer than that of the conventional inner rotor type motor, according to the mechanical formula T = F x D ( Torque = force x distance), the structure defined in this case has an increased linear distance from the rotor pole 322 to the output shaft 31, which further increases the torsion of the rotor 32. The electric motor 3 disclosed in the present invention provides the above two points to enhance the torsion force. Therefore, the hand-held power tool disclosed in the present invention has a torque greater than that of the conventional electric tool, and does not need to additionally provide a reduction gear set, which can save material cost and improve the gear. The problem of group space occupation and assembly difficulty.

Although the present invention has been disclosed above in the preferred embodiment, it is not intended to limit the present invention. Anyone who is familiar with this skill and does not deviate from the spirit and scope of this case, and some of the changes and refinements should be covered in this case. Therefore, the scope of protection of this case shall be subject to the definition of the scope of the patent application attached.

In summary, this case enhances the above-mentioned effects compared with the well-known creations. It should fully comply with the novelty and progressive statutory innovation patent requirements. If you apply in accordance with the law, you are requested to approve the invention patent application. Feeling the virtues.

1‧‧‧shell

10‧‧‧ventilation holes

2‧‧‧Control circuit

3‧‧‧Electric motor

30‧‧‧ Stator

301‧‧‧ core

302‧‧‧statar pole

303‧‧‧Exciting winding

304‧‧‧ bearing

305‧‧‧ bracket

306‧‧‧Axis hole

31‧‧‧Output shaft

32‧‧‧Rotor

321‧‧‧Induction Department

322‧‧‧Rotor magnetic pole

323‧‧‧Transmission Department

324‧‧‧ventilation holes

325‧‧‧ occlusion

4‧‧‧Face Leaf Group

5‧‧‧Processing tools

6‧‧‧Heat components

FIG. 1 is a schematic structural view of a hand-held power tool disclosed in the present disclosure.

Figure 2 is an exploded view of the electric motor.

Fig. 3 is a cross-sectional view (1) of the electric motor.

Figure 4 is a cross-sectional view (2) of the electric motor.

30‧‧‧ Stator

301‧‧‧ core

302‧‧‧statar pole

303‧‧‧Exciting winding

304‧‧‧ bearing

305‧‧‧ bracket

31‧‧‧Output shaft

32‧‧‧Rotor

321‧‧‧Induction Department

322‧‧‧Rotor magnetic pole

323‧‧‧Transmission Department

324‧‧‧ventilation holes

325‧‧‧ occlusion

4‧‧‧Face Leaf Group

5‧‧‧Processing tools

Claims (9)

A hand-held power tool for improving output efficiency, comprising a casing;
An electric motor is disposed in the housing, the electric motor includes a stator, a rotor and a power output shaft, the stator has a core and a plurality of stator poles radially extending from the core, the output shaft is rotatable Through the core, the rotor has a horizontally projected sensing portion covering the stator poles and a transmission portion fixedly coupled to the output shaft, the inner edge of the sensing portion having a plurality of rotor poles opposite to the stator poles, The rotor pole is magnetically coupled to the stator pole to induce a magnetic force to drive the output shaft to rotate relative to the stator;
The number of magnetic poles of the rotor is 16 to 36. A hand-held power tool according to claim 1, wherein the core portion includes a shaft hole through which the output shaft passes, and at least one bearing is provided in the shaft hole to support the output shaft. A hand-held power tool for improving output efficiency as described in claim 1, wherein the number of the rotor poles is 18 to 30. A hand-held power tool for improving output efficiency according to claim 1, wherein the output shaft includes a tool connection end exposed outside the core to connect a processing tool. A hand-held power tool for improving output efficiency according to claim 4, wherein the output shaft is coupled to a blade group at an opposite end of the processing tool. A hand-held power tool for improving output efficiency as described in claim 1, wherein the rotor is magnetically magnetized. A hand-held power tool for improving output efficiency according to claim 1, wherein the stator further has a bracket connected to the housing to position the stator in the housing. The hand-held power tool according to claim 1, wherein the stator pole is wound with a field winding, and a control circuit is further provided in the casing to supply electric power to the field winding according to a user operation. A hand-held power tool for improving output efficiency according to claim 1, wherein the hand-held power tool is further provided with at least one heat dissipating component.