JP3026615B2 - Electric saw - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric saw for cutting an object to be cut by driving a saw blade, and more particularly to an electric saw for performing speed change by forward and reverse rotation of a motor and a one-way clutch. .

[0002]

2. Description of the Related Art Electric saws, especially circular saws, are changing from those that only use conventional wood to those that use a wide variety of materials such as new building materials, molded products, mortar, iron plates, and glass. Yes, one saw blade cannot handle it.
For this purpose, a saw blade that matches the object to be cut must be used, but in this case, the cutting performance of the saw blade can be fully exhibited unless the saw blade is rotated at the appropriate number of revolutions. I can't let it. Therefore, this type of electric saw, especially a rechargeable type or a small type, which has a small output, must incorporate a speed change mechanism.

[0003] Here, there is a speed change mechanism using a pair of one-way clutches which transmit forward and reverse rotations of a motor, and transmit only one-way rotation and idle in the other direction.
This is, as shown in FIG.
2 and 23 are mounted via one-way clutches 24 and 24, respectively. One gear 22 is directly engaged with a pinion 25 provided on the output shaft of the motor 2, and the other gear 23 is an intermediate shaft supported by an intermediate shaft 26. By engaging with the pinion 25 via the gear 27, the motor 2
And the two gears 22 and 23 when the motor 2 rotates in one direction.
The rotation directions of 2, 23 are different.

When the motor 2 rotates in one direction, one of the gears 2 is used because the same direction in which power can be transmitted to the one-way clutches 24, 24 is used.
One-way clutch 2 located between the output shaft 3 and the output shaft 21
Although the idler 4 rotates, the rotation of the other gear 22 is transmitted to the output shaft 21 through the one-way clutch 24, and when the motor 2 rotates in the reverse direction, the rotation is transmitted to the output shaft 21 through the gear 23. The shift can be performed without requiring a physical operation such as a gear change.

[0005]

However, when the above-mentioned speed change mechanism is used for a circular saw, there are the following problems.
That is, since the one-way clutch is designed to spin in one direction, the output shaft is also free to rotate in one direction, so that the saw blade can be attached even if the rotation of the motor is stopped. The output shaft will continue to rotate for a period of inertia. In the case of a circular saw, it is dangerous that the saw blade keeps rotating even if the switch is turned off and the motor is stopped, and even if it is a standard, etc., the saw blade does not stop within a predetermined short time after the switch is turned off. It is determined not to be. In the case of an electric saw without a speed change function or an electric saw using another speed change mechanism, the saw blade is stopped within a short time by adding a brake circuit to the motor. In an electric saw using a mechanism, the saw blade continues to rotate even if a brake circuit is simply provided on the motor side.

[0006] The present invention has been made in view of such a point, and an object of the present invention is to provide a motor having a one-way clutch and a speed change mechanism capable of shifting by forward and reverse rotation of the motor. It is an object of the present invention to provide an electric saw capable of stopping the saw blade within a short time after the stop.

[0007]

Means for Solving the Problems] Thus the present invention, the forward and reverse
A free-running motor and one depending on the rotation direction of the motor
To move the output shaft to rotate in the same direction.
An electric saw having a clutch, a brake circuit for short-circuiting the motor in response to turning off of a power switch, and a brake for applying braking to rotation of an output unit to which the saw blade is connected in conjunction with turning off of a power switch. And a brake mechanism that has a brake shoe that is spring-biased toward the output section and comes into contact with the brake mechanism. An off-lock switch for locking the switch in an off state and the brake shoe are connected to each other, and the brake shoe is released when the off-lock switch is unlocked. This solenoid consists of a brake shoe that comes into contact with the output section when the solenoid is actuated. The solenoid is connected to a brake circuit to short-circuit the motor. And a third feature to operate the flow.

According to the present invention, when the power switch is turned off, the motor is immediately stopped by the brake circuit, and the saw blade is rapidly braked by the braking mechanism interlocked with the operation of turning off the power switch. To stop.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the illustrated embodiment. As shown in FIGS. The battery pack 11 is detachably attached to the other end of the housing 10. The remaining half circumference of the saw blade 3 projects below the base plate 15 and is covered by the movable cover 14.

Inside the one end of the housing 10,
As shown in FIG. 1, a motor 2 and a speed reduction mechanism block are accommodated, and a power switch 5 which is opened and closed by a switch handle 50 is accommodated in the center. As shown in FIG. 4, the speed reduction mechanism block connects the motor 2 to the drive shaft 31 on which the saw blade 3 is attached at one end by the holding plate 34 and the fixing screw 35.
A pair of gears 22 and 23 are attached to an output shaft 21 to which a gear 28 meshing with a gear 32 attached to the motor 2 is fixed via one-way clutches 24 and 24, respectively, and one of the gears 22 is a pinion provided on the output shaft of the motor 2. The gear 23 directly meshes with the pinion 25 via an intermediate gear 27 supported by an intermediate shaft 26.

When the motor 2 rotates in one direction, one of the gears 2 is used because the same direction in which power can be transmitted to the one-way clutches 24, 24 is used.
One-way clutch 2 located between the output shaft 3 and the output shaft 21
Although the idler 4 rotates, the rotation of the other gear 22 is transmitted to the output shaft 21 through the one-way clutch 24, and when the motor 2 rotates in the reverse direction, the rotation is transmitted to the output shaft 21 through the gear 23. Therefore, the saw blade 3 is driven to rotate in the same direction at different reduction ratios according to the rotation direction of the motor 3.

As shown in FIG. 1, a brake shaft 41 urged by a spring 42 is attached to the output shaft 21 here.
And a brake shoe 4 provided at the tip of the brake shaft 41
The brake shoe 40 of the brake mechanism 4 consisting of 0 is in contact with the brake mechanism 4. Also, the brake shoe 40
The brake is applied to the rotation of the output shaft 4 by being constantly in contact with the output shaft 21 under the bias of the spring 42. The braking is released in conjunction with the operation of the off-lock switch 6.

The off-lock switch 6 includes an off-lock lever 61 rotatable about a shaft 60 and a spring 6 for urging the off-lock lever 61 in one direction.
4. An off-lock pin 63 slidably provided with an engaging portion with a cam groove 62 formed on the off-lock lever 61, and disposed between the off-lock pin 63 and the off-lock lever 61. A spring 65 for biasing the off-lock pin 63.
Is the switch handle 5 of the power switch 5 at all times.
By locating one end of the power switch 5 at the base of the zero, the on operation of the power switch 5 is prevented.

The off-lock switch 6 and the brake mechanism 4 are linked to each other because the off-lock switch 61 slides with the rotation of the off-lock lever 61, and one end of the interlocking plate 47 abuts. The other end is a brake shoe 40
Is an interlocking pin 46 that is in contact with. The link pin 46 is urged toward the link plate 47 by a spring 47.

Now, if the off-lock lever 61 is rotated as shown in FIG. 5, the off-lock pin 63 slides due to the cam groove 62 and retreats from the root of the switch handle 63, and the power switch 5 Can be turned on. At this time, the interlocking plate 47 is turned off by the off-lock lever 6.
1 and slides, and the interlocking pin 46 is pushed toward the brake shoe 40 by the interlocking plate 47, so that the brake shoe 40 is separated from the output shaft 21.
One rotation is free. Therefore, if the power switch 5 is turned on by pulling the switch handle 50 in this state,
The rotation of the saw blade 3 is performed by the rotation of the motor 2, and the reduction ratio of the rotation of the saw blade 3 at this time varies depending on the rotation direction of the motor 2 as described above. The switch for changing the direction of rotation of the motor 2 is not shown. When the switch handle 50 is pulled, the switch handle 5
0 prevents the off-lock pin 63 from returning.
It is not necessary to apply an operating force to the off-lock lever 61 during the rotational drive of.

When the power switch 5 is turned off by releasing the finger from the switch handle 50 and restoring it, as shown in FIG. 6, the power switch 5 short-circuits the motor 2 from the a side in the figure. In order to switch to the brake circuit side b, the motor 2 stops rapidly. Also,
With the return of the switch handle 50, the off-lock pin 63 and the off-lock lever 61 also return, so that the interlocking plate 47 and the interlock pin 46 also return, and the brake shoe 40 comes into contact with the output shaft 21 and the one-way clutch. The rotation of the saw blade 3 is also stopped quickly to allow the braking system to be applied from 24 to the saw blade 3 side rotation system.

FIGS. 7 and 8 show another embodiment.
Here, a shaft 41 having a brake shoe 40 at one end is formed by a plunger of a solenoid 48, and is normally urged by a spring 49 from the output shaft 21 to the brake shoe 4.
0 is set apart. And the solenoid 48
Are connected in series to the brake circuit. Power switch 5
When the rotation of the motor 2 is stopped to stop the rotation of the motor 2, the current flowing in the brake circuit activates the solenoid 48 to bring the brake shoe 40 into contact with the output shaft 21 to apply braking to the rotation of the saw blade 3.

[0018]

As described above, in the present invention, when the power switch is turned off, the motor is immediately stopped by the brake circuit, and the saw blade is braked by the brake mechanism interlocked with the power switch off operation. It stops quickly, and a one-way clutch is provided in the power transmission path for shifting, so that even if the motor is braked, the output shaft has inertia.
Thus, the saw blade can be stopped within a short time after the motor is stopped , despite the fact that the rotation is to be continued .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a front view of the same.

FIG. 4 is a transverse sectional view of the same.

FIG. 5 is a vertical sectional view when the saw blade is rotated.

FIG. 6 is a schematic circuit diagram of the above.

FIG. 7 is a schematic circuit diagram of another embodiment.

FIG. 8 is a cross-sectional view of the same brake mechanism.

FIG. 9 is a sectional view of a speed change mechanism using a one-way clutch.

[Explanation of symbols]

 2 Motor 4 Brake mechanism 5 Power switch 21 Output shaft 24 One-way clutch

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-109358 (JP, A) JP-A-50-131191 (JP, A) JP-A-51-129728 (JP, A) 99708 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B27B 1/00-23/00 B23D 47/12 F16H 3/00

Claims (3)

(57) [Claims] 1. A motor capable of rotating forward and backward, and a method of rotating the motor.
One operates according to the direction to rotate the output shaft in the same direction.
An electric saw having two one-way clutches for driving, a brake circuit for short-circuiting a motor in conjunction with turning off of a power switch, and a rotation of an output unit to which a saw blade is connected in conjunction with turning off of a power switch. An electric saw, comprising: a brake mechanism for applying braking. 2. An off-lock switch which includes a brake shoe which is spring-urged toward an output portion and comes into contact with the output portion, and which locks a power switch to an off state in conjunction with an operation of turning off the power switch. 2. The electric saw according to claim 1, wherein the brake shoe is connected to the brake shoe, and the brake shoe is released when an off-lock switch is unlocked. 3. A brake mechanism comprising a solenoid and a brake shoe which comes into contact with an output portion by operation of the solenoid, wherein the solenoid is connected to a brake circuit and operates with a short-circuit current of a motor. The described electric saw.