JPH0347223Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of the Invention This invention relates to a sealing device for a switch lever for a power tool used in various power tools such as an electric screwdriver, an electric drill, and an electric saw.

(b) Background of the invention In recent years, slide-type switch mechanisms have become known for this type of power tools, which are set to turn the power tool on and off or control the motor torque by moving the operating lever. It is being

However, this sliding switch mechanism has an opening in the switch case that has the length of the pressing stroke to allow the pressing operation of the operating lever.
Because of this opening, the sealing performance deteriorates, and dust and the like enter from the outside through this opening, causing contact failure in the internal switch mechanism.

(c) Purpose of the invention Therefore, the object of this invention is to provide a sealing device for a switch lever for a power tool in which the sealing performance does not deteriorate even if it has an opening for sliding operation.

(d) Summary of the invention This invention provides a method for inserting a button between the opening of the switch case into which the operating end of the operating lever is inserted and the operating lever.
The present invention is characterized in that the sealing device for a switch lever for a power tool is equipped with a sealing plate that seals the opening in conjunction with the movement of the operating lever.

(e) Effects of the invention According to this invention, the gap between the opening of the switch case into which the end of the operating lever for operating the sliding switch mechanism is inserted and the operating end inserted into the opening is reduced. , because it is sealed with a seal plate that seals in conjunction with the movement of the operating lever,
This opening is always kept sealed even when the control lever is operated and when the device is not in use.

Therefore, this case action completely eliminates the intrusion of dust, etc. inside the switch case, and maintains highly reliable and stable switch performance without contact failure. can.

(F) Embodiment of the invention An embodiment of the invention will be described below in detail based on the drawings.

The drawings show a switch for a DC power tool, and in FIGS. 1 to 3, the switch for a DC power tool includes a control circuit section 11 for a DC motor, an operating lever 12 for driving and operating the motor, and a combination of these components. It is comprised of a supporting switch case 13, and is used, for example, by being incorporated into the grip of a power tool such as an electric screwdriver.

The control circuit section 11 described above includes a power transistor 14, an upper heat dissipation cover 15 that covers the power transistor from above and below, and a lower heat dissipation cover 16.
A printed circuit board 17 on which a control circuit is mounted, a resistance board 18 provided as a part of the speed change control circuit,
A brush 19 that changes the resistance value by slidingly contacting the resistance board 18, and first to third movable contact pieces 20 to
22, and a return spring 24 for this movable piece.

The power transistor 14 has a rectangular shape,
The three terminals 25 protruding from one side are bent downward and connected to a power supply terminal and a motor terminal, which will be described later, to turn on and off the armature circuit of the DC motor.
OFF control.

By the way, this kind of power transistor 14
generally generate heat easily, so the upper and lower heat dissipation covers 15 and 16 are made of metal that has better heat absorption than the upper and lower parts.
The heat generated by the power transistor 14 is absorbed.

In this case, the upper and lower surfaces of the power transistor 14 are held in close contact by the screws 26 passing through the upper and lower heat dissipation covers 15 and 16 from above and below to absorb heat. This close horizontal plane
These covers 15, 1 promote efficient heat absorption to the power transistor 14.
By increasing the vertical wall of transistor 6 and providing a large heat dissipation area of the cover itself,
4. This prevents performance deterioration and life expectancy due to heat generation.

The upper heat dissipation cover 15 is provided in the shape of a box with an open bottom surface, and the above-mentioned power transistor 14 and the lower heat dissipation cover 16 are housed and surrounded within the open bottom surface, and corners opened on both sides of the upper heat dissipation cover 15 are provided. The holes 27 engage with side protrusions 28 protruding from the outer surface of the switch case 13, which will be described later, and are integrally fitted onto the switch case 13.

The lower heat dissipation cover 16 is provided in a U-shape, and has square holes 29 opened on the side surfaces of both side hanging pieces of the U-shape.
is fitted onto the switch case 13 by engaging with a side protrusion 30 protruding from the outer surface of the switch case 13, which will be described later. In this case, stepped portions 31, 31 formed on both shoulders of the U-shape press down and support the printed circuit board 17, which will be described later, during installation.

The printed circuit board 17 described above is fixedly supported on the switch case 13 by having both side edges pressed down by the step portions 31, 31 of the lower heat dissipation cover 16. Further, a terminal connection hole 32 is formed vertically through one end of the substrate 17, and a power terminal and a motor terminal, which will be described later, are connected to this hole.

Further, slide guide surfaces 33 are cut out on both side edges of the printed circuit board 17, and an upper slide protrusion 34 of the movable piece 23, which will be described later, is slidably guided by the slide guide surface 33 to restrict the left and right steadiness when the movable piece slides. On the other hand, the movable piece comes into contact with the lower surface of the printed circuit board 17, and the upward movement of the movable piece 23 is restricted.

Furthermore, a thin resistance board 18 on which a resistance element for a speed change control circuit for the motor is printed is attached to the lower surface of the printed circuit board 17.

The above-mentioned movable piece 23 is provided in a box shape that can be stored in a switch case 13, which will be described later, and has a pair of press-fit holes 35, 3 opened at the rear side of the upper surface of this box shape.
5, the U-shaped first movable contact piece 20 is press-fitted from above, and one of the hanging pieces 36 and 37, which are vertically arranged in parallel on the lower surface of the box shape, has a wide U-shaped contact piece 20 attached thereto.
A shaped second movable contact piece 21 is attached by being press-fitted from below, and a narrow U-shaped third movable contact piece 22 is similarly attached to the other vertical piece 37 by being press-fitted from below.

Furthermore, the base end side of the brush 19 formed in an L shape is inserted and installed into the brush mounting groove 39 on the inside side through the brush opening 38 on the front side of the upper surface, and the brush 19 is attached to the left and right sides of the free end side of the brush. With the divided brush contact pieces 40, 40 being urged upward, these contact pieces 40, 40 are urged against the lower surface of the above-mentioned resistor board 18, and this brush 19 is integrated with the movable piece 23. By sliding and displacing the position in contact with the resistance board 18, the resistance value for controlling the torque of the motor changes, thereby changing the torque of the motor.

In this case, the brush 19, together with the movable piece 23,
It is usually located on one side and is set to have the maximum resistance value on one side and the minimum resistance value on the other side.

Further, upper slide protrusions 34 corresponding to the above-mentioned slide guide surfaces 33 are protruded from the four corners of the upper surface of the movable piece 23, and on the rear end side of the lower surface,
A spring seat hole 41 is formed, and this spring seat hole 41
One end of the return spring 24 is inserted therein, and the other end is inserted and locked in a spring seat hole 42 formed on the rear end side of the switch case 13, which will be described later.The return spring 24 is normally stored in a compressed state. Due to the biasing action of
The movable piece 23 is in a state of being urged forward.

Further, on the front end side of the lower surface of the movable piece 23, an operating shaft engagement hole 4 into which an operating shaft of an operating lever to be described later is inserted.
3 is open, and the operating lever 1 is connected via the operating shaft.
With the second pressing stroke, the movable piece 23 is slid in the front-back direction.

The above-mentioned switch case 13 is provided in a box shape with an open top surface, and the above-mentioned movable piece 23 is accommodated in the top surface opening 44 while being allowed to slide in the front and back direction, and the printed circuit board 17 and the power transistor 14 are placed above the movable piece 23. are installed via heat dissipation covers 15 and 16, and these upper and lower heat dissipation covers 15,
Each of the 16 square holes 27, 19... is connected to the switch case 1.
3 and are integrally fitted into each other by engaging with the respective side protrusions 28, 30, .

Furthermore, on the rear side wall 45 of the top opening 44,
Several terminal mounting grooves 46 are formed, and a first power terminal 47 and a second power terminal 48 are inserted into the terminal mounting grooves 46 on both sides, and the terminal mounting grooves 46 in between are inserted into the terminal mounting grooves 46 on both sides. , the first motor terminal 49, the second motor terminal 50, and the circuit connection terminal 51 are respectively inserted and attached.

As a result, the first power terminal 47 and the first motor terminal 49 are opposed to each other as a pair, and the second power terminal 48 and the second motor terminal 50 are opposed to each other as a pair.
Arc-shaped contact portions 52, 5 of these opposing tip portions
2, the vertical pieces 36 and 37 of the movable piece 23 are slidably sandwiched between them, and normally the first motor terminal 49 and the second motor terminal 50 are in contact with the first movable contact piece 20, respectively. The movable contact piece 23 is provided so as to come into contact with the second and third movable contact pieces 21 and 22 when the movable piece 23 is slid.

Further, on the rear end side of these terminals, transistor terminal insertion holes 53..., protrusions 54 for connecting to a printed circuit board, and connection holes 55 for connecting lead wires are formed as appropriate. The first and second power terminals 47 and 48 are connected to the electrodes of the battery, and the first and second motor terminals 49 and 50 are connected to a forward/reverse switch of the motor.

Note that the circuit connection terminal 51 directly connects the control circuits of the power transistor 14 and the printed circuit board 17 to each other.

A spacer 56 is provided opposite to the upper surface side of these terminals 47 to 51, and this spacer 56
is inserted and fixed into the upper center of the rear side wall 45 of the switch case 13, and the upper surface side of this spacer 56 is pressed down by the mounting action of the lower heat dissipation cover 16, and the lower surface of this spacer 56 connects each terminal 47 to 5.
1 is pressed down to prevent the terminal from coming out, and a hanging piece 57 is provided vertically at the center of the lower surface as a part of the spring seat hole 42 on the rear side of the switch case, and this spacer 56 is also provided. In particular, the rear end of the switch case is effectively sealed to improve dust resistance.

In addition, a pair of long grooves 58, 58 for guiding the movable piece sliding type are carved on both sides of the bottom surface of the top opening 44, and furthermore, in the center of the bottom surface, there is an operating shaft insertion hole opened along the front and back direction. 59 is provided, and an operating shaft of an operating lever, which will be described later, is inserted through this operating shaft insertion hole 59.

Further, a support piece 60 is vertically provided on the lower surface of the switch case 13, and this support piece 60 has a communication groove 61 that communicates with the above-mentioned operating shaft insertion hole 59 in the front-rear direction on the upper side, and has a communication groove 61 on both sides of the lower side. Pivot pin 62 on the surface,
62 is provided in a protruding manner, and an operating lever, which will be described later, is pivotally attached to these pivot pins 62, 62.

The above-mentioned operating lever 12 is provided in the shape of a half cylinder, and this cylindrical surface is set as the push-down operation surface 63 on the front side, and the pivot hole 64 at the bottom of the lever is pivoted to the above-mentioned pivot pin 62. As a result, the operating lever 12 can freely tilt forward and backward using the lower end as a fulcrum, and furthermore, the upper end of the operating shaft 65, which is engaged with the intermediate part of the lever and is planted, is inserted through the communication groove 61 and the operating shaft insertion hole 59. The operation shaft engagement hole 43 of the movable piece 23
When the operating lever 12 is tilted, the movable piece 23 is slid in the front-rear direction.

In this case, the operation shaft insertion hole 59 is provided with a rectangular seal plate 66 and a bellows-shaped seal cover 67 that is located below the case plate 66 and surrounds the outer periphery of the operation shaft 65. There is.

This seal plate 66 is an upper elastic seal piece 6 made of rubber, sponge, etc. to improve sealing performance.
8 and a lower resin seal piece 69 made of a resin material such as polyester film having the required strength are attached from above and below to provide an elastic function and durability suitable for sealing performance. ing.

A slit 70 is formed on the upper elastic seal piece 68 side in the longitudinal corresponding portion with the operation shaft 65, and an operation shaft engagement hole 71 with approximately the same cross-sectional shape as the operation shaft 65 is formed on the lower resin seal piece 69 side. The operating shaft 65 is inserted through the operating shaft 65, and the outer circumference of the operating shaft 65 is set to have as little clearance as possible.

For this reason, the seal plate 66 is provided integrally with the operating shaft 65 and similarly slides in the longitudinal direction in conjunction with the longitudinal movement of the operating shaft 5.

Note that this seal plate 66 is attached to the switch case 1.
It is engaged with a seal plate slide groove 72 carved in the front-rear direction on the lower surface of No. 3, and is stably slid.

Further, the seal cover 67 is provided in a cylindrical bellows shape that allows movement of the operating shaft 65.
The gap between the and the operating shaft engaging hole 71 is sealed even more airtight.

In this way, the seal plate 66 and the seal cover 67
By arranging these, the operation shaft insertion hole 59 is in a completely sealed state, and dust is completely prevented from entering through the insertion hole portion of the operation lever 12 which is tilted.

Furthermore, in this case, as shown in FIG. 4, a coil spring 73 is arranged in a compressed state around the outer periphery of the seal cover 67, and the above-mentioned seal plate 66 is pushed from below by the biasing action of this spring 73. The seal plate 66 may be biased to be stably positioned within the seal plate slide groove 72.

Further, an O-ring may be interposed between the seal plate 66 and the switch case 13 to further improve sealing performance.

The DC power tool switch configured as described above is disposed in the grip of the power tool, and the operating lever 12 is normally biased and tilted forward from the front of the grip using the lower end as a fulcrum. The protruding button is in a state where it can be pressed.

By pressing down this operating lever 12, the movable piece 23 interlocked with this lever slides backward, and in this sliding process, the arc-shaped contact portions 52 of the first and second motor terminals 49, 50, 5
2 separates from the first movable contact piece 20 and becomes non-contact,
At the same time, the first power terminal 47, the first motor terminal 49, and the second movable contact piece 21 are contacted. As a result, the power is turned on and the motor is started.At this time, by adjusting the stroke of the operating lever 12, the contact position between the brush 19 via the speed change control circuit of the power transistor 14 and the resistance board 18 is displaced. As a result, the torque of the motor is variably controlled, and the output torque is adjusted to suit the usage of the power tool.

Then, when the operating lever 12 is pressed down to its full stroke, the movable piece 23 slides to the rear end position, and the second power terminal 48 and the second motor terminal 5
0 comes into contact with the third movable contact piece 22.

As a result, the power transistor 14 of the speed change control circuit is short-circuited, the motor torque is fully opened, and high output is achieved.

Next, when the pressing operation of the operating lever 12 is released, the movable piece 2 receives the return action of the return spring 24.
3 slides to the front end side, and the operation lever also returns to its original forwardly protruding inclined state, and the first and second power terminals 47, 48 and the second and third movable contact pieces 21 are linked to this. , 22 are out of contact with each other, and the power is turned off.

In this case, as soon as the power is turned off,
The first and second motor terminals 49 and 50 respectively contact the original first movable contact piece 20, and due to this contact action, a counter electromotive force is generated on the motor side that rotates due to inertia immediately after the power is turned off. is generated, and this back electromotive force applies a braking effect to the motor, instantly stopping the motor rotation, and providing OFF control suitable for stopping operations while using a power tool.

On the other hand, a seal plate 66 and a seal cover 67 are provided for the operation shaft insertion hole 59 opened on the lower surface of the switch case 13 to seal the operation shaft insertion hole 59 in conjunction with the movement of the operation shaft 65. Therefore, for the inside of this switch case 13,
There is no opening that communicates with the inside, and the intrusion of dust and chips from the power tool from the outside is completely eliminated, resulting in a highly reliable and high-performance power tool that can always provide stable switch operation.

In terms of the correspondence between the structure of this invention and the embodiment described above, the operating lever of this invention corresponds to the operating lever 12 of the embodiment, and similarly, the switch case corresponds to the switch case 13, and the operating lever of this invention corresponds to the operating lever 12 of the embodiment. The mechanism includes a movable piece 23,
The opening corresponds to the operating shaft insertion hole 59, the operating end corresponds to the operating shaft 65, and the sealing plate corresponds to the sealing plate 66. However, the present invention is not limited to the configuration of the embodiment described above.

[Brief explanation of the drawing]

The drawings show one embodiment of this invention; FIG. 1 is an exploded perspective view of a switch for a DC power tool, FIG. FIG. 4 is a longitudinal sectional view of a switch for a DC power tool showing another embodiment of this invention. 12... Operation lever, 13... Switch case, 23... Movable piece, 47, 48, 49, 50,
51...Terminal, 59...Operation shaft insertion hole, 65...
Operation axis, 66...Seal plate.

Claims (1)

[Scope of Claim for Utility Model Registration] A switch for a power tool that controls an internal switch mechanism by movement of an operating lever whose operating end is engaged with a sliding switch mechanism inside a switch case, comprising: A sealing device for a switch lever for a power tool, wherein a sealing plate is installed between the opening of a switch case into which an operating end is inserted and the operating lever, the sealing plate interlocking with the movement of the operating lever and sealing the opening.