CN110571982A

CN110571982A - electric tool

Info

Publication number: CN110571982A
Application number: CN201810577500.XA
Authority: CN
Inventors: 王士豪; 洪文星
Original assignee: CHEWANG ELECTRONIC Co Ltd
Current assignee: CHEWANG ELECTRONIC Co Ltd; Mobiletron Electronics Co Ltd
Priority date: 2018-06-06
Filing date: 2018-06-06
Publication date: 2019-12-13
Anticipated expiration: 2038-06-06
Also published as: CN110571982B

Abstract

An electric tool comprises a shell, a motor, a first circuit board and a second circuit board, wherein the shell comprises a transmission part and a handheld part; the motor and the first circuit board are positioned in the transmission part, and the second circuit board is positioned in the handheld part; the first circuit board is provided with a plurality of phase-change switch elements, a plurality of Hall sensors and a first controller. The first controller receives a driving signal and controls the phase change switch element to change the phase according to the driving signal and a position signal of the Hall sensor; the second circuit board is electrically connected with the first circuit board through a transmission line group; the second circuit board is provided with a second controller, and the second controller transmits a driving signal to the first controller through the transmission line group. Therefore, the number of signal lines of the transmission line group between the first circuit board and the second circuit board is effectively reduced.

Description

Electric tool

Technical Field

The present invention relates to power tools; and more particularly to a design that facilitates wiring within the housing of the power tool.

Background

Fig. 1 and 2 show a conventional electric tool 1, which includes a housing 10, a motor 14, an upper circuit board 16 and a lower circuit board 18, wherein the housing 10 has a transmission portion 102 and a hand-held portion 104, the transmission portion 102 is provided with the motor 14 and a driving mechanism (not shown), and the motor 14 is a three-phase dc brushless motor; the handheld portion 104 is provided with an operation interface 12, and the operation interface 12 is operated by a human to generate an operation signal.

The upper circuit board 16 is disposed on the transmission portion 102, and six commutation switch elements 162 and three hall sensors 164 are disposed on the upper circuit board 16, the commutation switch elements 162 are used for controlling the commutation of the motor, and the hall sensors 164 sense the position of the rotor of the motor 14.

The lower circuit board 18 is disposed in the handle portion 104 of the housing 10, the lower circuit board 18 is electrically connected to the battery port 20 for receiving power from the battery 22, and a controller 182 is disposed on the lower circuit board. The lower circuit board 18 is electrically connected to the operation interface 12, so that the controller 182 receives the operation signal from the operation interface 12. The lower circuit board 18 is electrically connected to the upper circuit board 16 through a transmission line group 24, which includes nine control signal lines for transmitting the control signals of the commutation switch elements 162 and five position signal lines for transmitting the output signals of the hall sensors 164. After receiving the operation signal from the operation interface 12, the lower controller 182 generates the control signal for controlling the commutation switch elements 162 according to the operation signal and the hall sensor output signals from the five position signal lines, and transmits the control signal to the commutation switch elements 162 of the upper circuit board 16 through the nine control signal lines to control the commutation switch elements 162 to perform commutation, so that the rotor of the motor 14 rotates.

Since at least 14 signal lines are required for the transmission line group 24 between the upper circuit board 16 and the lower circuit board 18, the arrangement of 14 signal lines in the limited space between the hand-held portion 104 and the transmission portion 102 will result in overcrowding, which is not favorable for the wiring of the transmission line group 24 during assembly.

Disclosure of Invention

In view of the above, an object of the present invention is to provide an electric power tool, which can reduce the number of signal lines in a transmission line group and facilitate the wiring in a housing.

In order to achieve the above object, the present invention provides an electric tool, which includes a housing, a motor, a first circuit board and a second circuit board, wherein the housing includes a transmission portion and a hand-held portion; the motor is arranged in the transmission part; the first circuit board is positioned in the transmission part of the shell, a plurality of phase-change switch elements, a plurality of Hall sensors and a first controller are arranged on the first circuit board, wherein the first controller is electrically connected with the phase-change switch elements and the Hall sensors, the phase-change switch elements are electrically connected with the motor, and the Hall sensors sense the position of a rotor of the motor and generate a position signal; the first controller receives a driving signal and controls the phase change switch elements to change the phase according to the driving signal and the position signal so as to enable the rotor of the motor to rotate; the second circuit board is positioned in the handheld part of the shell and is electrically connected with the first circuit board through a transmission line set; the second circuit board is provided with a second controller, and the second controller transmits the driving signal to the first controller through the transmission line group.

The invention has the advantages that the first controller in the first circuit board controls the switching of the phase change switch element, so that the number of signal lines of the transmission line group between the first circuit board and the second circuit board can be effectively reduced, and the wiring of the transmission line group is facilitated in the limited space between the handheld part and the transmission part of the shell.

[ brief description of the drawings ]

Fig. 1 is a schematic view of a conventional power tool.

Fig. 2 is a system block diagram of a conventional electric power tool.

Fig. 3 is a schematic view of a power tool according to a preferred embodiment of the present invention.

Fig. 4 is a system block diagram of the electric tool of the preferred embodiment.

Fig. 5 is a perspective view of the motor of the electric power tool according to the preferred embodiment.

Fig. 6 is an exploded perspective view of the motor of the electric power tool according to the preferred embodiment.

Fig. 7 is a waveform diagram of the outputs of the three hall sensors and the rotation speed signal in the preferred embodiment.

[ notation ] to show

[ conventional ]

1 electric tool

10 housing 102 drive 104 handpiece

12 operator interface 14 circuit board on motor 16

162 commutation switch element 164 hall sensor 18 lower circuit board

182 controller 20 battery port 22 battery

24 transmission line group

[ invention ]

2 electric tool

30 housing 302 drive 304 handpiece

32 operator interface 34 Motor 342 body

344 rear cover 346 heat sink pad 36 first circuit board

362 commutation switch element 364 hall sensor 366 first controller

38 second circuit board 382 second controller 40 battery port

42 battery 44 transmission line group 441 speed signal line

442 brake signal line 443 power line 444 ground wire

445 rotation direction signal line 446 current signal line 447 rotation speed signal line

V1 first Voltage level V2 second Voltage level

V3 third Voltage Standard V4 fourth Voltage Standard

Detailed Description

In order that the invention may be more clearly described, preferred embodiments will now be described in detail with reference to the accompanying drawings. Referring to fig. 3 to 6, an electric tool 2 according to a preferred embodiment of the present invention includes a housing 30, a motor 34, a first circuit board 36 and a second circuit board, wherein:

The housing 30 includes a transmission portion 302 and a handle portion 304, wherein the transmission portion 302 is provided with a motor 34 and a driving mechanism (not shown), and a rotation shaft of the motor 34 is used for driving the driving mechanism; the handheld portion 304 is held by a human, and the handheld portion 304 is provided with an operation interface 32, the operation interface 32 is operated by the human to generate an operation signal, in this embodiment, the operation interface 32 includes a start switch and a steering switch, and the operation signal includes a start command, a steering command, and the like. In practice, the operation interface at least comprises a start switch, and the operation signal at least comprises a start command.

the motor 34 is a three-phase dc brushless motor in the present embodiment, and includes a main body 342, a rear cover 344 and a heat dissipation pad 346, wherein the main body 342 has a stator (not shown), the main body 342 has a rotor (not shown) therein, a rotating shaft of the motor 34 is connected to the rotor and protrudes from the front side of the main body 342, and the rotating shaft is connected to the driving mechanism. The rear cover 344 is disposed at the rear side of the body 342, the heat dissipation pad 346 is disposed between the rear cover 344 and the body 342, and the heat dissipation pad 346 and the rear cover 344 have a heat conduction relationship, which may be direct contact between the heat dissipation pad 346 and the rear cover 344 or heat conduction through a heat dissipation paste.

The first circuit board 36 is disposed in the transmission portion 302 of the housing 30, and in the embodiment, the first circuit board 36 is disposed between the body 342 and the heat dissipation pad 346. The first circuit board 36 is provided with a plurality of commutation switch elements 362, a plurality of hall sensors 364 and a first controller 366, wherein the first controller 366 is electrically connected to the commutation switch elements 362 and the hall sensors 364, the commutation switch elements 362 are six MOSFETs in the present embodiment and are electrically connected to the stator of the motor 34, and the commutation switch elements 362 and the heat dissipation pad 346 have a thermal conduction relationship, which may be that the commutation switch elements 362 and the heat dissipation pad 346 are directly contacted or thermally conducted through a heat dissipation paste. The hall sensors 364 are three and respectively used for sensing the position of the rotor of the motor 34, the output of each hall sensor 364 is changed between a first voltage standard and a second voltage standard, and the hall sensors 364 respectively output pulses in sequence when the rotor rotates 120 degrees, so as to form a position signal in the form of pulses. The first controller 366 receives a driving signal and controls the phase-change switching elements 362 to perform phase change according to the driving signal and the position signal, so as to rotate the rotor of the motor 34. In this embodiment, the first voltage standard is exemplified by a low voltage standard, and the second voltage standard is exemplified by a high voltage standard.

the second circuit board 38 is disposed in the hand-held portion of the housing 30, the second circuit board 38 is electrically connected to the battery port 40 for receiving power from the battery 42, and a second controller 382 is disposed on the second circuit board 38. The second circuit board 38 is electrically connected to the operation interface 32, so that the second controller 382 receives the operation signal from the operation interface 32 and converts the operation signal into a driving signal. In addition, the second circuit board 38 is electrically connected to the first circuit board 36 through a transmission line group 44, and the second controller 382 transmits the driving signal to the first controller 366 through the transmission line group 44.

Therefore, when the first controller 366 receives the driving signal, the phase-change switching elements 362 are controlled to perform phase change according to the driving signal and the position signal, so as to rotate the rotor of the motor 34. Since the phase-change control is performed by the first controller 366 on the first circuit board 36, and the second controller 382 on the second circuit board 38 does not need to control the phase-change switch elements 362 to perform phase-change switching, the electric tool 2 of the present invention can effectively reduce the number of signal lines in the transmission line group 44 compared to the conventional electric tool.

In this embodiment, the transmission line group 44 includes a speed signal line 441 and a brake signal line 442; the driving signal generated by the second controller 382 according to the start command of the operation signal at least includes a speed command and a braking command, the speed command is transmitted through the speed signal line 441, the braking command is transmitted through the braking signal line 442, and after receiving the driving signal, the first controller 366 controls the phase-change switching element 362 according to the speed command to perform the switching speed of the phase change so as to control the rotation speed of the rotor, or controls the phase-change switching element 362 according to the braking command to stop the rotation of the rotor. The speed command is transmitted in the present embodiment in a PWM manner, and a longer PWM duty cycle represents a faster speed.

The transmission line set 44 includes a power line 443 and a ground line 444 for transmitting power from the second circuit board 38 to the first circuit board 36. In response to the steering command of the operation signal, the transmission line group 44 includes a steering direction signal line 445; the driving signal generated by the second controller 382 according to the steering command of the operation signal includes a rotation direction command transmitted through the rotation direction signal line 445, and the first controller 366 receives the driving signal and controls the commutation switch element 362 according to the rotation direction command, so that the rotor rotates according to the steering set by the steering switch of the operation interface 32. The transmission line group 44 further includes a current signal line 446; the driving signal comprises a current command for setting the current of the motor 34 during operation, the current command is transmitted through the current signal line 446, and the first controller 366 receives the driving signal and controls the commutation switch 362 according to the current command to limit the current of the motor 34 during operation. The current command is transmitted in the present embodiment in a PWM manner, and a longer PWM duty cycle represents a higher current.

In order to facilitate the second controller 382 to obtain the rotation speed of the rotor of the motor, in the embodiment, the transmission line set 44 includes a rotation speed signal line 447, the first controller 366 converts the position signals sensed by the three hall sensors 364 into a rotation speed signal, the rotation speed signal is transmitted to the second controller 382 through the rotation speed signal line 447, and the second controller 382 determines the rotation speed of the motor 34 according to the rotation speed signal. Referring to fig. 7, in the present embodiment, the method for converting the position signal into the rotation speed signal includes that the first controller 366 changes the rotation speed signal from a third voltage level V3 to a fourth voltage level V4 when the output of each hall sensor 364 is converted from the first voltage level V1 to the second voltage level V2, and the first controller 366 changes the rotation speed signal from the fourth voltage level V4 to the third voltage level V3 when the output of each hall sensor 364 is converted from the second voltage level V2 to the first voltage level V1. In the present embodiment, the third voltage reference V3 is exemplified by the low voltage reference, and the fourth voltage reference V4 is exemplified by the high voltage reference. In other words, the rotation speed signal has a pulse variation of one cycle every 120 degrees of rotation of the rotor, the rotation speed signal has a pulse of three cycles every one rotation of the rotor, and the second controller 382 can calculate the rotation speed of the rotor according to the pulse cycle of the rotation speed signal, so that the number of signal lines of the transmission line group 44 can be effectively reduced by integrating the outputs of the three hall sensors 364 into one. In practice, the output of one of the hall sensors 364 in the position signal may be used as a rotation speed signal by the first controller 366, and the rotation speed of the rotor may be calculated by the second controller 382 according to the pulse period output by one of the hall sensors 364.

Additionally, the speed signal line 447 may not be provided if the second controller 382 does not need to obtain the speed. Also, if the temperature of the commutation switch element 362 is required to be obtained by the second controller 382, a temperature sensing element (not shown) may be disposed on the first circuit board 36, and the temperature of the commutation switch element 362 is measured by the temperature sensing element, and the transmission line set 44 may include a temperature signal line (not shown) for transmitting an output signal of the temperature sensing element to the second controller 382.

As mentioned above, the power tool of the present invention adds the first controller 366 to the first circuit board 36, and controls the switching of the phase-change switch element 362 via the first controller 366, so that the number of signal lines of the transmission line set 44 can be effectively reduced, and the wiring of the transmission line set 44 is facilitated in the limited space between the handheld portion 304 and the transmission portion 302 of the housing 30.

The above description is only a preferred embodiment of the invention, and all equivalent variations to the description and claims of the present invention are intended to be included within the scope of the present invention.

Claims

1. A power tool, comprising:

A housing including a transmission portion and a hand-held portion;

A motor arranged in the transmission part;

The first circuit board is positioned in the transmission part of the shell and is provided with a plurality of phase change switch elements, a plurality of Hall sensors and a first controller, wherein the first controller is electrically connected with the phase change switch elements and the Hall sensors, the phase change switch elements are electrically connected with the motor, and the Hall sensors sense the position of a rotor of the motor and generate a position signal; the first controller receives a driving signal and controls the phase change switch elements to change the phase according to the driving signal and the position signal so as to enable the rotor of the motor to rotate;

The second circuit board is positioned in the handheld part of the shell and is electrically connected with the first circuit board through a transmission line set; the second circuit board is provided with a second controller, and the second controller transmits the driving signal to the first controller through the transmission line group.

2. The power tool of claim 1, wherein the transmission line set includes a speed signal line and a brake signal line; the driving signal comprises a speed command and a braking command, the speed command is transmitted through the speed signal line, and the braking command is transmitted through the braking signal line.

3. The power tool of claim 2, wherein the speed command is transmitted in a PWM manner.

4. The power tool of claim 2, wherein the transmission line set further comprises a rotation direction signal line; the driving signal includes a rotation direction command transmitted through the rotation direction signal line.

5. The power tool of claim 2, wherein the transmission line set further comprises a current signal line; the driving signal includes a current command, which is transmitted through the current signal line.

6. The power tool of claim 5, wherein the current command is transmitted in a PWM manner.

7. The power tool of claim 1, wherein the transmission line set includes a rotational speed signal line; the first controller converts the position signal into a rotation speed signal, the rotation speed signal is transmitted to the second controller through the rotation speed signal line, and the second controller judges the rotation speed of the motor according to the rotation speed signal.

8. The power tool of claim 7, wherein the output of each hall sensor is switched between a first voltage level and a second voltage level; the first controller changes the rotating speed signal from a third voltage standard to a fourth voltage standard when the output of each Hall sensor is converted from the first voltage standard to the second voltage standard; the first controller changes the rotation speed signal from the fourth voltage standard to the third voltage standard when the output of each Hall sensor is changed from the second voltage standard to the first voltage standard.

9. The power tool of claim 1, wherein the motor includes a body, a back cover disposed on the body, and a heat sink pad disposed between the back cover and the body; the first circuit board is arranged between the body and the heat dissipation pad, and the phase change switch elements and the heat dissipation pad are in heat conduction relation.

10. The power tool of claim 9, wherein the heat sink pad is in heat-conducting relation with the back cover.