JP2003339184A - Brushless dc motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless DC motor of a motor driver 1 which can rotate at the highest efficiency even in the state of forward or reverse rotation. <P>SOLUTION: In the brushless DC motor 10 of the motor driver 1, a Hall IC 34 can be switched to the forward rotation detecting position and a reverse rotation detecting position of a rotor, by disposing a detecting substrate 32 fixing the IC 34 out of a motor casing 30, inserting the detector of the IC 34 into the casing 30, movably disposing a detecting substrate 32 by a changeover switch 40, and movign a detecting substrate 32 by the switch 40. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless DC motor capable of normal rotation and reverse rotation.

[0002]

2. Description of the Related Art A brushless DC motor (hereinafter simply referred to as a motor) is capable of normal rotation and reverse rotation. That is, a magnetic detection element such as a Hall IC that detects the rotational position of the rotor is provided in the vicinity of the rotor of the motor, and a rotation direction instruction signal for instructing forward rotation and inversion input from the outside, and a rotation speed instruction signal, The control circuit controls the inverter circuit based on the detection signal from the magnetic detection element, and outputs the drive signal from the inverter circuit to the coil of the motor.

By the way, when the magnetic detecting element detects the rotational position of the rotor, as shown in the hysteresis graph of FIG. 8, the normal rotation (CW) position and the reversal (CCW) position which can be detected with the highest efficiency. Are different from each other, and as shown in FIG. 9, they are in a state of being shifted by α ° about the rotation axis O of the rotor.

[0004]

However, in the conventional motor, as shown in FIG. 9, the magnetic detection element is fixed at the neutral position of the detection position of the highest efficiency of forward rotation and reverse rotation.

If the magnetic detection element is fixed at the neutral point as described above, there is a problem in that it is impossible to rotate the motor at the highest efficiency in both forward rotation and reverse rotation.

In view of the above problems, the present invention provides a brushless DC motor that can be rotated with maximum efficiency even in the normal rotation and reverse rotation states.

[0007]

According to a first aspect of the present invention, in a brushless DC motor having a magnetic detection element for detecting a rotational position of a rotor, a detection substrate to which the magnetic detection element is fixed is provided in the brushless DC motor. By arranging outside the casing, the detecting portion of the magnetic detecting element is inserted inside the casing, the detecting substrate is movably arranged by the switching means, and the detecting substrate is moved by the switching means. The detection unit can switch between a forward rotation detection position of the rotor and a reverse rotation detection position of the rotor, which is a brushless DC motor.

According to a second aspect of the present invention, the detection substrate is arranged coaxially with a rotation shaft of the brushless DC motor, and the detection substrate is rotatably arranged around the rotation shaft by the switching means. Claim 1 characterized by the above.
It is the described brushless DC motor.

According to a third aspect of the present invention, in the brushless DC motor according to the first or second aspect, the detection substrate is separate from the drive circuit substrate having the drive circuit of the brushless DC motor. is there.

According to a fourth aspect of the present invention, the brushless DC motor is a drive source of an electric tool, and the brushless DC according to at least one of the first to third aspects.
It is a motor.

According to a fifth aspect of the present invention, the brushless DC motor is a drive source for an industrial machine, and the brushless D according to at least one of the first to third aspects.
It is a C motor.

According to a sixth aspect of the present invention, the brushless DC motor is a drive source for home electric appliances, and the brushless DC is at least one of the first to third aspects.
It is a motor.

[0013]

[Operation] With the brushless DC motor of the present invention, the detection unit of the magnetic detection element can switch between the forward rotation detection position and the reverse rotation detection position of the rotor by moving the detection substrate by the switching means. Therefore, the normal rotation and the reverse rotation can be performed with the highest efficiency.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A brushless DC motor (hereinafter, simply referred to as a motor) 10 according to a first embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In the first embodiment, a case where the motor 10 is used as a drive source of a cordless driver drill (hereinafter, simply referred to as an electric driver) 1 which is one of electric tools will be described.

(1) Structure of the electric screwdriver 1 As shown in FIG. 2, the electric screwdriver 1 has a motor 10 at the rear of the body of a pistol type frame 12, and a gearbox in front of the motor 10. 14 is arranged, and a chuck portion 16 for attaching a drill, which is a tool, is attached to the output shaft of the gearbox 14.

An operating portion 18 having a trigger 46 for driving the electric driver 1 is provided above the grip portion of the frame 12, and a battery 20 for driving the motor 10 is provided below the grip portion. It is built in.

A drive circuit board 22 containing a drive circuit for driving the motor 10 is arranged below the gear box 14 on the body of the frame 12.

(2) Structure for Forward and Reverse Rotation of Motor 10 Next, the structure for forward and reverse rotation of the motor 10 will be described.

Inside the motor casing 30 of the motor 10, a ring-shaped stator 24 and a rotor 26 are rotatably arranged on the inner circumference of the stator 24 via bearings. Rotor 2
A rotary shaft 28 at the center of 6 is connected to the gearbox 14.

A disk-shaped detection substrate 32 is rotatably provided outside the motor casing 30 and coaxially with the rotary shaft 28. It should be noted that it does not rotate at the same time as the rotary shaft 28.

The Hall IC 34, which is a magnetic detection element, projects from the rear surface of the detection substrate 32, and the motor casing 3
It is inserted into the inside of the motor casing 30 through a fan-shaped through hole 36 that is open on the front surface of 0. This Hall IC3
4 is arranged so that the magnetism of the magnet of the rotor 26 can be detected.

FIG. 3 is a view of the detection substrate 32 viewed from the front, and the Hall IC 34 rotates as the detection substrate 32 rotates. When it comes to the position on the right side of FIG. 3, the Hall IC 34 can detect the magnetism from the rotor 26 at the highest efficiency in forward rotation, and when it comes to the left position, it comes out of the rotor 26 at the highest efficiency in reversal. Each of them can be rotated and moved to the position where the magnetism is detected. It should be noted that both of these positions are obtained in advance by testing and design.

The crank 3 is provided on the outer peripheral portion of the detection substrate 32.
8 is provided and is connected to a pin 42 protruding from the changeover switch 40 that moves in the left-right direction in FIG. That is, the elongated hole 44 is opened in the crank 38,
The pin 42 is inserted into the elongated hole 44.

The crank 38 is connected to a forward / reverse changeover switch in the operation section 18,
By moving the changeover switch 40, the forward rotation and reverse rotation changeover units of the operation unit 18 are also changed over at the same time.

As shown in FIG. 3, the changeover switch 40 protrudes from the left and right of the frame 12 of the electric driver 1 and can be moved in the left and right direction by a human hand from the outside.

(3) Method of Using Electric Driver 1 A method of using the electric driver 1 having the above configuration will be described.

When the electric driver 1 is used in the normal rotation, the changeover switch 40 is moved to the right side by the human hand in FIG. 3 so that the Hall IC 34 is moved to the normal rotation detection position, and the operating section 18 is operated. Trigger 4
Press 5 to rotate the electric screwdriver 1 in forward rotation.

On the other hand, in the case of reversing use, the changeover switch 40 is pushed to the left side in FIG.
34 is rotated to the left and fixed at the reversal detection position. Then, the trigger 45 of the operation unit 18 is pushed to push the electric screwdriver 1
Invert.

With the electric screwdriver 1 having the above-mentioned structure, by switching the changeover switch 40, the Hall IC 34 is rotationally moved to the optimum position for normal rotation and reverse rotation, and normal rotation and reverse rotation can be performed at the highest efficiency. .

(Second Embodiment) A second embodiment will be described with reference to FIG.

The difference between the second embodiment and the first embodiment is that the position of the operating portion 18 and the position of the detection substrate 32 are
This is the case where the motor 10 is displaced along the direction of the rotation axis.

In this case, as shown in FIG. 4, a bent portion 48 is provided on the crank 38 to shift the crank 38, and a C-shaped retaining ring or an E-shaped retaining ring is provided at the engaging portion with the pin 42. To use.

(Third Embodiment) A third embodiment will be described with reference to FIG.

The difference between the third embodiment and the first embodiment is the structure of the crank 38.

That is, in this embodiment, the changeover switch 40 and the lower end of the crank 38 are fixed, and the detection substrate 3 is fixed.
The pin 50 is protruded from the outer peripheral portion of the crankshaft 2 to connect the long hole 52 in the upper portion of the crank 38 to the pin 50.

Even with this structure, the changeover switch 4
By moving 0 in the left-right direction, the detection substrate 3
2 can be rotated.

(Fourth Embodiment) A fourth embodiment will be described with reference to FIG.

The difference between the fourth embodiment and the first embodiment is the structure of the crank 38.

That is, in the present embodiment, the crank 38
A fulcrum 54 fixed to the frame 12 is provided midway, and elongated holes 56 and 58 are provided in the upper and lower portions of the crank 38, respectively. Further, pins 60 and 62 are provided on the detection substrate 32 and the changeover switch 40, respectively, so that the slot 56 and the pin 60
To engage the elongated hole 58 with the pin 62.

Even with this structure, the changeover switch 4
When 0 is moved to the left and right, the crank 38 moves to the fulcrum 54
The detection substrate 32 can also be rotated by rotating about.

(Fifth Embodiment) A fifth embodiment will be described with reference to FIG.

The difference between the fifth embodiment and the first embodiment is the structure of the crank 38.

That is, in this embodiment, the frame 12
The crank 38 is attached so as to rotate around a fulcrum 74 fixed to the. The elongated hole 64 is provided in the lower portion of the crank 38 and is engaged with a pin 66 protruding from the changeover switch 40. Further, on the upper part of the crank 38, a gear 68 engraved along an arc is provided. On the other hand, the detection board 32 is also provided with a gear plate 72 having a gear 70 engraved along the arc shape, and the gear 70 of the gear plate 72 and the gear 68 of the crank 38 are screwed together.

With this structure, the changeover switch 40
Is moved in the left-right direction, the crank 38 rotates about the fulcrum 74, the gear plate 72 rotates due to the gear 70 and the gear 68 being screwed together, and the detection substrate 32 is also rotated.
Also rotates.

(Application Example) In the above embodiment, the cordless driver drill, which is one of the electric tools, has been described, but a cordless driver, a driver drill having a cord, or a driver may be used.

Further, it can be used not only in electric tools but also in industrial machines. For example, the structure of the part where the tool is attached and detached by the chuck in the machine tool, and the bite (cutting tool) in the lathe (NC control lathe etc.) of the machine tool.
In the case of processing a cutting object, the rotating direction in the case of using the front cutting tool is opposite to that in the case of using the rear cutting tool, so that it may be used for such a lathe.

Further, it may be used as a drive source for household appliances. For example, it may be used as a drive source of a direct drive type washing machine in which a washing tub is directly rotated by a motor, or a pump of a dishwasher. Moreover, you may use as a drive source of the compressor for air conditioners.

(Modification) In the above embodiment, the detection board 32 and the drive circuit board 22 are provided separately, but instead of this, a drive circuit may be provided on the detection board 32.

[0050]

As described above, according to the present invention, since the magnetic detection element can be moved by the switching means to the position of the highest efficiency for forward rotation and reverse rotation, the brushless DC motor is rotated forward and reverse. Can be rotated with maximum efficiency.

[Brief description of drawings]

FIG. 1 is a perspective view of an electric screwdriver according to a first embodiment.

FIG. 2 is a side view of an electric screwdriver.

FIG. 3 is a front view of a detection board, a crank, and a changeover switch.

FIG. 4 is a perspective view of an electric screwdriver according to a second embodiment.

FIG. 5 is a front view of a detection board, a crank, and a changeover switch according to a third embodiment.

FIG. 6 is a front view of a detection board, a crank, and a changeover switch according to a fourth embodiment.

FIG. 7 is a front view of a detection substrate, a crank, and a changeover switch according to a fifth embodiment.

FIG. 8 is a hysteresis graph for a rotor magnet.

FIG. 9 is a diagram showing the position of the Hall element with respect to the position of the rotor.

[Explanation of symbols]

1 electric screwdriver 10 motors 12 frames 22 Drive circuit board 24 Stator 26 rotor 28 rotation axis 30 motor casing 32 detection board 34 Hall IC 36 through holes 38 cranks 40 changeover switch 42 pin 44 long hole 46 Trigger

Claims (6)

[Claims] 1. A brushless DC motor having a magnetic detection element for detecting a rotational position of a rotor, wherein a detection substrate to which the magnetic detection element is fixed is arranged outside a casing of the brushless DC motor, and the magnetic detection element is provided. Of the detection unit is inserted into the casing, the detection substrate is movably arranged by the switching unit, and the detection unit is moved by the switching unit, so that the detection unit is A brushless DC motor capable of switching between a rotation detection position and a rotation reversal detection position of the rotor. 2. The detection substrate is arranged coaxially with a rotation shaft of the brushless DC motor, and the detection substrate is arranged to be rotatable around the rotation shaft by the switching means. The brushless DC motor according to claim 1. 3. The brushless DC motor according to claim 1, wherein the detection board is separate from a drive circuit board having a drive circuit for the brushless DC motor. 4. The brushless DC motor according to claim 1, wherein the brushless DC motor is a drive source of an electric tool. 5. The brushless DC motor according to claim 1, wherein the brushless DC motor is a drive source of an industrial machine. 6. The brushless DC motor according to claim 1, wherein the brushless DC motor is a drive source for home electric appliances.