JPH0622902Y2 - Dust protection device for power tool switches - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a switch for an electric tool such as used for various electric tools such as an electric driver, an electric drill, an electric saw, etc. The present invention relates to a dustproof device for a switch for electric tools, which has improved dustproof performance at a lever mounting portion.

(B) Conventional Technology In recent years, as a switch for this kind of electric tool, a slide-type switch is known which can simultaneously perform ON / OFF operation and output control of the electric tool by the movement of one operation lever. (For example, Japanese Patent Application No. 60-160916 of the prior application.
issue).

In this case, since the operation lever connected to the switch mechanism inside the switch case is inserted into the switch mechanism inside by inserting the end portion of the lever into the inside of the lower opening of the switch case, A plate-shaped or accordion-shaped seal rubber is provided to protect the internal contact portion from the bottom opening that is opened for the stroke length of the lever so that dust and the like do not enter from the outside.

However, this sealing rubber has a complicated shape such as a bellows, and the positioning work for the opening on the lower surface requires time and labor, resulting in a high cost.

Therefore, a switch with improved dustproof performance is provided by using a movable elastic plate and a fixed elastic plate for sealing which are flat plate shapes that are easy to manufacture and are easy to position and attach (for example, the characteristics of the prior application). Japanese Patent Application No. 62-269824).

However, in this case, a small gap is formed on the side of the opening of the elastic plate with which the lever end engages, and fine dust may intrude along with the movement of the operation lever through this small side gap. The dustproof structure could not be taken.

(C) Problems to be solved by the invention This invention is a dustproof device for a power tool switch, which has a simple dustproof member but has a highly dustproof structure in which the gap to the lower opening of the switch case is completely eliminated. The purpose is to be.

(D) Means for Solving the Problems The present invention is provided with an elastic opening formed at the opening on the lower surface of the switch case to allow the upper end engaging portion of the operating lever to move by the stroke length. A fixed elastic plate, and a movable elastic plate attached to the upper end engaging portion of the operation lever corresponding to the elastic opening of the fixed elastic plate, and an electric motor for controlling the internal switch mechanism by the movement of the operation lever. A dustproof device for a tool switch, wherein a lower end pivotal support portion of the lever is pivotally supported on both side shoulder portions sandwiching an upper end engaging portion of the operation lever, which correspond to lower surface positions on both sides of an elastic opening portion of the fixed elastic plate. As a dust-proof device for a switch for an electric tool, an arc-shaped contact-corresponding surface is formed on the lower surface of the fixed elastic plate for constant contact.

According to the present invention, the fixed elastic plate and the movable elastic plate are arranged corresponding to the lower surface opening of the switch case, and the operation is performed on both lower surface positions of the elastic opening of the fixed elastic plate. The operation lever is mounted in a state where the contact corresponding surfaces formed on both shoulders of the lever are always in contact with each other.

(F) Effect of the invention Therefore, the lower surface opening of the switch case can be substantially closed by the plate-shaped fixed elastic plate and the movable elastic plate, and the elastic opening of the fixed elastic plate can be closed. The contact surface of the lever, which sandwiches the upper end engaging part of the operating lever, has an arc shape centering on the rotation fulcrum, and can always contact the lower surface of both sides of the fixed elastic plate with a constant pressure. Therefore, even if a small gap is formed on the side of the elastic opening of the fixed elastic plate, the gap is sealed to completely eliminate the room for dust to enter, and the two-stage dust-proof structure of the elastic plate and the contact corresponding surface. Thus, the dustproof performance can be reliably enhanced, and therefore, the switch performance with high contact reliability with respect to the contact portion of the switch can be maintained.

In particular, when the lever is not used, it is of course possible to completely close the opening on the lower surface of the switch case, and the opening is always kept closed even when the lever is operated.

(G) Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

The drawings show a switch for a DC electric tool, and in FIGS. 2 to 4, the switch for a DC electric tool includes a control circuit section 11 of a DC motor, an operation lever 12 for driving and operating the motor, and an integrated body thereof. The switch case 13 supports the switch case 13, which is used by being incorporated in a grip portion of an electric tool such as an electric screwdriver.

The control circuit unit 11 described above includes a power transistor 14,
An upper heat radiating cover 15 that covers the power transistor 14 from above and below, a lower heat radiating cover 16, a printed circuit board 17 on which a control circuit is mounted, and a resistance value control surface provided on the lower surface of the printed circuit board 17 in sliding contact with each other. The brush 18 has a variable value, a slider 22 having first and second movable contact pieces 20 and 21 biased by the pressing springs 19 and 19, and a return spring 23 of the slider.

The above-mentioned power transistor 14 has a quadrangular shape, and a caulking hole 24 for mounting is provided in the extending portion on the front end side, and is attached to an upper heat dissipation cover 15 described later through the caulking hole 24. Three output control terminals 25 ... Are provided on the rear end side, and the free ends of these terminals 25 ... are bent downward and connected to a printed circuit board 17, which will be described later. ON / OFF control.

By the way, since this kind of power transistor 14 generally easily generates heat, the upper and lower heat radiation covers 15, which are made of metal such as aluminum alloy having good heat absorption from the top and bottom,
It is covered with 16 to absorb the heat generated by the power transistor 14.

The upper heat dissipation cover 15 is provided in a box shape having an open lower surface, and a rivet 26 effective for heat dissipation is used with the upper part of the power transistor 14 fitted and held in the lower surface recess 15a formed in the cover. , The upper heat dissipation cover 15
The power transistor 14 is caulked and attached to the. Then, with the lower heat radiation cover 16 housed and surrounded, the square holes 2 opened on both side surfaces of the upper heat radiation cover 15.
7 are engaged with side projections 28, which are provided on the outer surface of the switch case 13, which will be described later, and are integrally fitted onto the switch case 13. In this case, the upper heat dissipation car 15 is provided with a sufficiently large area not only on the horizontal surface side but also on the vertical surface side in order to enhance heat dissipation, and also provided in a box shape so as to cover the entire switch, and also has dustproof performance. At the same time, it is formed to raise.

The lower heat dissipation cover 16 is provided with its U-shaped opening facing downward, and allows the lower part of the power transistor 14 to be fitted and held in the upper surface recessed portion 16a formed in the cover, and the side surfaces of both side hanging pieces of the cover 16. Square hole 29 ...
Similarly, the switch case 13 is fitted on the switch case 13 by engaging with a side projection 30 protruding to the outer side surface of the switch case 13, which will be described later. In this case, the step portion 31 formed on the inner side surface presses and supports the printed circuit board 17 in correspondence with the edge of the printed circuit board 17 described later. Similarly, the heat dissipation cover 16
In order to enhance the heat dissipation, the area of not only the horizontal surface side but also the vertical surface side is set to be sufficiently large. This allows
The performance and life of the power transistor 14 are prevented from being deteriorated due to heat generation.

The printed circuit board 17 has the electronic components for the control circuit mounted on the upper surface thereof, the resistance value control surface is printed on the lower surface thereof, and the periphery of the upper surface is pressed by the step portions 31, 31 of the lower heat dissipation cover 16. , Is fixedly supported on the switch case 13.

Further, at the rear end position of the printed board 17, each burring 32 for terminal connection is vertically formed, and the terminal 25 of the power transistor 14 and a power supply terminal and a motor terminal which will be described later are assembled from above and below. However, this assembly insertion portion is soldered and efficiently connected.

The burring 32 annularly penetrates the terminal connection position of the printed circuit board 17 by a conductive member, and each hole edge is efficiently connected to the control circuit of the printed circuit board 17 by wiring. And
A slider 22 is provided opposite to the lower surface of the printed board 17.

The above-mentioned slider 22 is provided in a box shape that can be housed in the switch case 13, and an L-shaped brush is formed in the brush mounting groove 34 through the brush opening 33 on the front side of the upper surface of the box shape. The base end side of 18 is inserted and attached, and the brush contact pieces 35, 3 divided into left and right on the tip side of the brush.
5 is urged upward, these contact pieces 35, 35
Comes into contact with the resistance control surface on the lower surface of the printed circuit board 17 described above, and the brush 18 slides integrally with the slider 22 to displace the contact position with the resistance control surface.
The resistance of the motor for torque control is changed to control the output of the motor.

The brush 18 is supported by a slider 22 which is biased to the front side and is normally set to have a maximum resistance value on the front side and a minimum resistance value on the rear side. .

Further, a spring seat hole 36 is provided in the center of the rear end side of the slider 22, and the return spring 2 is provided in the spring seat hole 36.
One end side of 3 is inserted, and the other end side is inserted and locked in a spring seat 37 formed on the rear end side of the switch case 13 described later, and is normally stored in a compressed state, and is extended by the expansion biasing force of the spring 23. , The slider 22 is biased forward.

Further, an operation shaft engaging hole 38 into which an operation shaft 53 of the operation lever 12 to be described later is inserted is opened on the front end side of the lower surface of the slider 22, and a slider is pressed by the operation shaft 53 to move the operation lever 53. 22 is moved in the front-rear direction and slide-operated.

The switch case 13 described above is provided in the shape of a box with an open upper surface, and the slider 22 described above is provided in the upper surface opening 39.
Is accommodated so as to be slidable in the front-rear direction, and the printed circuit board 17 and the power transistor 14 are mounted above the same via the upper and lower heat radiation covers 15 and 16.

Further, the first power supply terminal 41 and the second power supply terminal 42 are press-fitted and fixed to both sides of the rear side wall 40 of the upper surface opening 39, and the first motor terminal 43 and the second motor are preliminarily provided between these terminals 41 and 42. The terminals 44 are arranged in the switch case 13 by insert molding.

Then, the contact surfaces 41a, 43a of the first power supply terminal 41 and the first motor terminal 43 are arranged so as to be exposed on the upper surface in the front-rear direction on one side of the bottom surface of the upper surface opening 39, and the upper surface opening portion 39 is also provided. The contact surfaces 42a, 44a of the second power supply terminal 42 and the second motor terminal 44 are arranged so as to be exposed on the upper surface in the front-rear direction on the other side of the bottom surface of the base plate, and the brake terminal 45 is press-fitted and fixed on the front surface side of the bottom surface. In the same way, contact surfaces 45 should be
a, 45a are arranged so as to be exposed on the upper surface, and these contact surfaces 4
1a to 45a are arranged on a flat surface having the same height, and arc-shaped contact portions 20a, 20a, 2
First and second movable contact pieces 20, 21 provided with 1a, 21a
Of the movable contact pieces 20 and 21
It is provided so that the motor output can be switched by sliding the motor in the front-back direction.

In this case, the above-mentioned first and second motor terminals 43 and 44 are set to the common terminals located in the middle portion in the slide front-rear direction, and normally, the first and second movable contact pieces 20 and 21 are common respectively. It is in a non-conductive state corresponding to the terminals and the brake terminal side, and when the slider 22 is slid, the first
The movable contact piece 20 separates from the contact surface 45a on the brake side and contacts the contact surface 41a of the first power supply terminal 41 to establish conduction between the contact surfaces 41a and 43a on the first terminal side, and the second movable contact. Similarly, the piece 21 is the contact surface 45a on the brake side.
The contact surface 42a of the second power supply terminal 42 and the contact surface 42a on the second terminal side are provided so as to be electrically connected to each other.

Further, on the upper surface of each of the terminals 42 to 44 corresponding to the rear side wall 40, a ring for connecting a printed circuit board, which can be inserted into the hole of the burring 32 from below and the terminal 25 of the power transistor can be inserted from above. Connector 42b, 43
b, 44b are provided so as to stand up, and these annular connectors 42
The b, 43b, and 44b are attached in a state of being erected from the upper surface of the rear side wall 40. Then, the ring-shaped connectors 42b of the terminals and the terminals 25 of the power transistors are collectively inserted into the holes of the burring 32 of the printed circuit board 17 mounted here, and the burring 32 portion thus inserted is soldered. By doing so, they are efficiently and integrally connected. Further, the rear ends of the power supply terminal and the motor terminal are connected to the switch case 1
3, which is located outside of 3 and has a crimp terminal connection portion 4 at these rear end portions.
1c, 42c, 43c, 44c are formed respectively, and these connecting portions are not a soldering method but a crimping method, so that the connecting work can be simplified and the productivity can be improved.

On the other hand, the first and second power supply terminals 41 and 42 are connected to the electrodes of the battery via crimp terminals not shown, and similarly, the first and second motor terminals 43 and 44 are connected to the positive electrodes of the motor via crimp terminals. It is connected to the reverse rotation changeover switch.

A pair of guide surfaces 46, 46 for guiding the slider are formed on both side walls of the upper surface opening 39, and an operation shaft insertion hole 47 opened along the front-rear direction is provided in the center of the bottom surface. The operation shaft of the operation lever 12 described later is inserted through the operation shaft insertion hole 47.

Further, a support piece 48 is vertically provided on the lower surface of the switch case 13, and the support piece 48 has a communication groove 49 communicating with the operation shaft insertion hole 47 in the front-rear direction on the upper side, and on both sides on the lower side. Pivot pins 50, 50 are projectingly provided on the surface, and an operation lever 12 described later is pivotally attached to the pivot pins 50, 50.

The above-mentioned operating lever 12 is provided in a half-cylindrical shape, and this cylindrical surface is set as the front-side pressing operation surface 51, and the pivot hole 52 at the lower part of the lever is pivotally attached to the pivot pin 50. By doing so, the operation lever 12 can be tilted in the front-rear direction about the lower end as a rotation fulcrum, and the top portion of the operation shaft 53 erected in the lever intermediate portion is connected via the communication groove 49 and the operation shaft insertion hole 47. The slider 22 is engaged with the operation shaft engaging hole 38 of the slider, and the slider 22 is slid in the front-rear direction in accordance with the tilting operation of the operation lever 12.

In this case, the fixed sponge plate 5 for sealing is inserted into the operation shaft insertion hole 47 formed in the lower surface of the switch case 13.
4 and the movable sponge plate 55 are arranged.

The fixed sponge plate 54 has a hollow opening 56 formed in the central portion thereof so as to open the operation stroke length of the operation shaft 53. The operation shaft 53 is allowed to be inserted from below through the hollow opening 56. The lower part of 54 is a central recess 5 described later.
8, the upper surface on the front end side is pressed and supported by the central portion of the brake terminal 45 mounted on the upper surface to be fixed. Then, the movable sponge plate 55 is placed on the upper surface of the fixed sponge plate 54.

The movable sponge plate 55 has a small insertion engaging hole 57 for inserting and engaging the top of the operation shaft 53 from below on the front side so as to seal even a slight gap, and to prevent the operation lever from moving. It is provided to obtain interlocking dustproof performance.

Further, in this case, as shown in FIG. 1, the lower end pivotal support portion of the operation lever 12 is pivoted on both side shoulder portions sandwiching the operation shaft 53 corresponding to the lower surface positions on both sides of the hollow opening portion 56 of the fixed sponge plate 54. As a fulcrum, arc-shaped contact-corresponding surfaces 59, 59 are formed on the lower surface of the fixed sponge plate 54 so as to always contact.

The contact surfaces 59, 59 described above are formed in a stepped manner on both lower sides sandwiching the operation shaft 53 in the middle portion, and these are in contact with the lower surfaces on both sides of the hollow opening 56 of the fixed sponge plate 54, and further between this. Arc-shaped central protrusion 60 formed to project in the middle
However, in a state of facing the inside of the hollow opening 56 of the fixed sponge plate 54 and corresponding to the stepped closing, the operation shaft 53 standing upright in this intermediate portion is engaged with the operation shaft engagement hole 38 of the slider 22 to be assembled. .

As a result, the sealing performance of the fixed sponge plate 54 with respect to the hollow opening 56 is improved, and even a small gap that is easily formed on the side of the hollow opening 56 is sealed, and dust is completely prevented from entering from the outside. .

By the way, these sponge plates 54 and 55 are provided with a central recessed portion 58 which is a recessed portion including the above-mentioned operation shaft insertion hole 47 in the central portion of the upper surface opening portion 39 of the switch case,
The sponge plates 54 and 55 described above are fitted and disposed in the central recess 58 from above. As a result, a high and low stepped portion is formed with both sides of the bottom surface of the switch case 13 on the upper side and the central portion on the lower side, the contact portion of the switch mechanism is formed on the upper side, and the sealing portion by both sponge plates is formed on the lower side. Therefore, the intrusion of dust from below the switch case is prevented.

Further, by providing the central concave portion 58, both sponge plates 54 and 55 arranged therein are naturally positioned in the concave portion, and the central concave portion 58 is not required to be attached by caulking or the like.
It can be assembled simply by mounting it so that it fits in.

Further, even if a small amount of dust is present in the switch case 13, the step is formed by the central concave portion 58, so that the dust does not enter the switch contact portion above it. As described above, the sponge plates 54 and 55 can be reliably sealed against the outside of the switch case and the stepped portion can be sealed against the inside of the switch case.

Further, in the fixed sponge plate 54, the hollow opening 5
6 is provided on the front end side of 6 so as to temporarily receive the return reaction force of the operation shaft 53 biased and inserted therein and elastically absorb it, thereby reducing the load applied to the lever itself,
Is made of resin instead of metal so that it can be easily molded.

The switch for a DC power tool having such a configuration is arranged at the grip portion of the power tool, and normally, this operation lever 12
Is subjected to an urging action, and is in a state in which the lower end is a fulcrum and can be pushed forward by inclining and projecting forward from the front surface of the grip portion.

Then, when the operation lever 12 is pushed down, the slider 22 slides backward in conjunction with this lever, and the first and second movable contact pieces 20, 21 come out of contact with the brake terminal 45 in the sliding process, and The first movable contact piece 20 contacts the first power supply terminal 41 and the first motor terminal 43, and the second movable contact piece 21 contacts the second power supply terminal 42 and the second motor terminal 44.
To contact. As a result, the power is turned on and the motor starts.

At this time, the stroke adjustment based on the depression stroke of the operation lever 12 displaces the contact position between the brush 18 and the resistance value control surface of the printed circuit board 17, which causes the torque of the motor to pass through the shift control circuit of the power transistor 14. Is variably controlled and adjusted to a desired output torque suitable for the usage situation of the power tool.

Then, when the operation lever 12 is pressed down to the full stroke, the slider 22 slides to the rear end position, the torque of the motor is fully opened, and high output operation is performed.

Next, when the operation lever 12 is pressed and released, the slider 22
Receives the return action of the return spring 23, slides to the front end side, and in conjunction with this, the operation lever 12 returns to the original tiltable protruding position that can be pressed, and interlocks with this.
The second movable contact pieces 20 and 21 are not in contact with the first and second motor terminals 43 and 44, and the power is turned off.

By the way, when assembling this switch, first, the operation lever 12 is pivotally attached to the support piece 48 vertically provided on the lower surface of the switch case 13, and the operation shaft 53 at the upper end of the lever is inserted through the operation shaft insertion hole 47. The fixed sponge plate 54 and the movable sponge plate 55 are placed through the operation shaft 53 so as to face the upper opening 39 in the case 13, and the lower side of the switch case 13 is assembled.

Next, the first power supply terminal 41 and the second power supply terminal 42 are press-fitted and fixed to both sides of the rear side wall 40 of the switch case 13, and the brake terminal 45 is press-fitted and fixed to the front side of the upper surface opening 39.

Furthermore, the first and second movable contact pieces 20, 21 are provided on these upper surfaces.
Is mounted, and the upper surface thereof is fitted and held by the slider 22 so as to be urged by the pressing springs 19 and 19 and urged and contacted from above,
These switch parts are mounted one by one and assembled. After that, the printed circuit board 17 and the lower heat dissipation cover 1
6, the power transistor 14, and the upper heat dissipation cover 15 are similarly sequentially mounted and assembled.

The operation shaft insertion hole 47 of the switch case 13 assembled in this manner can be substantially closed by a plate-shaped fixed sponge plate 54 and a movable sponge plate 55, and a hollow opening of the fixed sponge plate 54. With respect to the portion 56, on both lower surfaces of the fixed sponge plate 54, both contact corresponding surfaces 59, 59 of the lever 12 sandwiching the operation shaft 53 of the operation lever 12 are circles centering on a rotation fulcrum of the lower part of the lever. Since it has an arcuate shape and is always in contact with a constant pressure, even if a small gap is formed on the side of the hollow opening 56 of the fixed sponge plate 54, it is sealed to completely eliminate the room for dust to enter. The two-step dustproof structure of the sponge plates 54 and 55 and the contact-corresponding surfaces 59 and 59 can surely enhance the dustproof performance, and therefore, the switch performance with high contact reliability with respect to the contact portion of the switch can be maintained.

Especially, when the operation lever 12 is not used, the switch case 1
The operation shaft insertion hole 47 on the lower surface of 3 can be completely closed, and the operation shaft insertion hole 47 is always kept closed even when the lever 12 is operated.

In the correspondence between this invention and the configuration of the above-mentioned one embodiment, the switch mechanism of this invention corresponds to the first and second movable contact pieces 20 and 21 and each terminal 41 to 45 of the embodiment, and Similarly, the lower surface opening of the switch case corresponds to the operation shaft insertion hole 47, the upper end engagement portion of the operation lever corresponds to the operation shaft 53, the fixed elastic plate corresponds to the fixed sponge plate 54, and the movable The elastic plate corresponds to the movable sponge plate 55, and the elastic opening of the fixed elastic plate corresponds to the hollow opening 56. However, the present invention is not limited to the configuration of the above-described embodiment.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is an enlarged perspective view of an essential portion showing an upper end engaging portion of an operating lever, FIG. 2 is an exploded perspective view of a switch for a DC electric tool, and FIG. FIG. 4 is a vertical sectional side view of the switch for tools, and FIG. 4 is a vertical sectional front view of the switch for DC electric tools. 11 ... Control circuit part, 12 ... Operation lever 13 ... Switch case, 20, 21 ... Movable contact piece 41-45 ... Terminal, 47 ... Operation shaft insertion hole 53 ... Operation shaft, 54 ... Fixed Sponge plate 55: Movable sponge plate, 56: Hollow opening 59: Contact surface

Claims (1)

[Scope of utility model registration request] 1. A fixed elastic plate, which is provided with an elastic opening formed in an opening on a lower surface of a switch case to allow an upper end engaging portion of an operating lever to move by a stroke length, and the fixed elastic plate. And a movable elastic plate attached to the upper end engaging portion of the operation lever in correspondence with the elastic opening of the electric tool switch for controlling the internal switch mechanism by the movement of the operation lever. The lower ends of the lever are always in contact with the lower surface of the fixed elastic plate at both side shoulders sandwiching the upper end engaging portion of the operation lever, which correspond to the lower surface positions on both sides of the elastic opening of the fixed elastic plate. A dustproof device for switches for electric tools that has a corresponding arc-shaped contact surface.