JPH02172119A - Switch for power tool - Google Patents

Abstract

PURPOSE:To ease assembling with the return spring in a lateral advance slider side eliminated and the number of parts reduced by automatically making the switching between contact parts of sliders by making a lateral advance slider a lateral advance action while interlocking with the initial slide action of a straight advance slider. CONSTITUTION:When a switch for a D.C. power tool is provided at the grip part of the tool and an operating lever 13 is made a push-down operation against a slider return spring 32, a straight advance slider 28 interlocking with the lever 13 slides rearward, and following the action of the slider 28, a contact possible to straight advancing contacts a front fixed contact 30 to be short-circuited, an electric source is made to 'ON', and a motor is started in a normal rotation direction. At that time, a working pin 37 pushes a first direction change lever 38 based on the push-down stroke of the lever 13 in the initial stage, a lateral advance slider 40 interlocking with this action laterally advances in the lateral direction, a lateral advance movable contact contacts a rear fixed contact 44 for output control, and a small turning force needed at the time of the positioning of a machine screw can be obtained. At that time, when the lever 13 is fully pushed down for the whole stroke, high output can be obtained at a stretch, and an electric source is made to 'OFF' with pushing-down released.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a switch for switching power ON/OFF, forward/reverse rotation, etc. of various power tools such as electric screwdrivers and electric drills. This invention relates to a switch for power tools that has a simplified structure.

(B) Conventional technology Normally, this type of power tool switch is capable of controlling the motor's ON/OF tfi operation and arbitrary number of rotations of the motor, as shown in, for example, Japanese Patent Application No. 62-288228, which was previously filed. Several independent contact mechanisms are internally constructed to switch the polarity of the motor and operate the motor in forward and reverse directions.

However, such a contact mechanism has a large number of components inside the switch, such as the need to be equipped with a return spring for each movable contact piece inside, and there are limits to simplifying the structure and simplifying assembly. It was happening.

(c) Problems to be Solved by the Invention The object of the invention is to provide a switch for a power tool that can reduce the number of parts, simplify the structure, and simplify assembly.

(d) Means for Solving the Problems The present invention is a switch for a power tool that controls the output of a motor based on a switching operation between contact portions, and which is biased toward the front of a switch case and is attached to the bottom surface of the switch case. A linear slider for push-down operation equipped with a linear movable contact, a fixed contact for switching operation that is arranged at the bottom of the switch case and corresponds to the linear movable contact and comes into contact with and separates from the linear movable contact, and a support that allows the linear slider to move laterally. The actuating pin, each direction changing lever having one front end corresponding to the actuating pin with the intersection of the two pieces intersecting in a scissor shape as a tilting fulcrum, and engaging with the rear end of each of the direction changing levers. , and a lateral slider equipped with a lateral movable contact on the lower surface, a fixed contact for output control that is arranged at the bottom of the switch case and corresponds to contact and separation with the lateral movable contact, and a fixed contact that protrudes outward from the switch case. A switch for a power tool includes a forward/reverse switching lever that selectively switches the motor between a forward rotation side and a reverse rotation side by laterally moving the operating pin.

(E) Function of the Invention According to the present invention, by pressing down the linear slider biased and projected forward of the switch case, the linear movable contact contacts and separates from the fixed contact for switching operation to perform switching operation of the motor, At the initial stage of this pressing, the lateral slider that engages with one direction conversion lever via the actuating pin moves laterally, and during this lateral movement, the lateral moving movable contact contacts and separates from the fixed contact for output control to control the motor output. Fine control.

(F) Effects of the Invention In this way, the lateral slider can be moved laterally in conjunction with the initial sliding movement of the straight slider.
Since the contact portions of both sliders can be switched in conjunction with the movement of the linear slider, the return spring on the transverse slider side can be omitted. As a result, it is possible to accurately reduce the number of parts, simplify the structure, and simplify assembly.

(g) Example of actual repair An embodiment of the present invention will be described in detail below based on the drawings.

The drawing shows a switch for a DC power tool, and in FIGS. 1 and 2, this DC power tool switch includes a DC motor control circuit section 11, a switch case 12 that houses and supports the control circuit section 11, and a motor control circuit section 11. This is used by being incorporated into the grip of a power tool such as an electric screwdriver, for example.

The above-mentioned control circuit section 11 includes a power transistor 14,
A dustproof cover 15 that covers each terminal part of the power transistor 14 from above, a transistor support 16 that holds the power transistor 14, a printed circuit board 17 that mounts a control circuit, and a switching mechanism 18 that turns the motor on and off. , a motor fine output control mechanism 19, and a motor forward/reverse switching mechanism 20.

The above-mentioned power transistor 14 has a rectangular shape, and three terminals 21 protruding from the side surface thereof are bent downward to form predetermined power terminals and motor terminals 22 which are insert-molded in the switch case 12. ... to control the ON/OFF of the armature circuit of the DC motor.

The transistor support 16 has the power transistor 14 attached to the upper surface by caulking with rivets 23, and the lower surface side surrounds and clamps the printed circuit board 17, so that the switch case is connected to the switch case by engaging hanging pieces 24 hanging down from the four corners. 12 and is integrally attached.

The printed circuit board 17 is clamped and fixed between the upper and lower sides of the transistor support 16 and the switch case 12.
The dustproof cover 15 is attached by engaging the protrusions 26 of the dustproof cover 15 with the engagement holes 25 formed in the -rpJrIM portion of the board 17, and each terminal connection hole 2 of the board 17.
7... are connected to power terminals and motor terminals 22....

The above-mentioned switching a mechanism 18 includes a linear slider 28,
It is composed of two linear movable contacts attached to the lower surface and a front fixed contact 30, and is housed inside the switch case 12, and the linear slider 28 is located inside the upper opening 31 of the switch case 12. Normally, the linear slider 28 is moved back and forth by the extension biasing action of the slider return spring 32, which is compressed between the inner end surface of the linear slider 28 and the inner end surface of the switch case 12. This straight slider 28 is biased forward and moved.
The push-down shaft 33 protruding from the front end face of the switch case 12 is biased forward from the front opening 35 of the switch case 12 via the front sealing material 34 for dustproofing.

Further, on the lower surface of the linear slider 28, one linearly movable contact 29 with an inverted M shape is attached with a biasing contact spring 36 for promoting contact pressure, and this contacts the bottom surface of the switch case 12. A front fixed contact 30 for switching operation is insert-molded on the front bottom surface of the switch case 12, which slides and moves straight, and corresponds to this straight-moving movable contact 29.

The operating lever 13 is attached to the outer end of the push-down shaft 33 described above.
One end of the operating lever 13 is pushed down, and the straight-moving slider 28 moves straight against the slider return spring 32. At the end of this straight-moving movement, the moving straight-moving contact 29
constitutes a slide type switch that short-circuits in response to contact with the front fixed contact 30 and switches from OFF to ON to start the motor.

The aforementioned motor fine output control device 19 includes an operating pin 37, first and second direction conversion levers 38 and 39, and first and second direction change levers 38 and 39.
Lateral sliders 40, 41, lateral movable contacts 42, 43 attached to the lower surface of these sliders, and rear fixed contacts 44,
... and is housed in the switch case 12.

The actuating pin 37 has a pin 37a standing up on its upper surface and an engaging protrusion 37b vertically provided on its lower surface, and the engaging protrusion 37b is provided on the upper surface of the linear slider 28 to allow lateral movement. Allowing and engaging support. This lateral movement permissible engagement portion 4
5 has a concave and convex shape, and is provided so as to provide resistance when the actuating pin 37 moves laterally, thereby providing a feeling of operation.

The first and second direction conversion levers 38 and 39 are provided with both levers intersecting in a scissor-like shape, and in both intersecting holes 46 at the intersecting position.
A common fulcrum pin 47, which will be described later, is inserted to maintain the scissor-like shape.
Both levers 38 and 39 are allowed to tilt individually using this intersection position as a tilting fulcrum.

In this case, both levers 38 and 39 are arranged above the linear slider 28 with the pin 37a of the actuating pin 37 interposed between the opposing surfaces of the front ends of the levers. As a result, 0! When the forward slider 28 moves forward, the front end of one lever 38 receives the pressing force in the straight direction of the actuating pin 37, which moves forward together with the slider 28, and the rear end of one lever 38 moves outward using the intersection as a tilting fulcrum. The direction is changed and moves in the horizontal direction. Note that since the other lever 39 is not subjected to any pressing force, it does not tilt and maintains its original standby state.

First and second lateral sliders 40, 41 are attached to the rear end portions of each lever 38, 39.

These lateral sliders 40, 41 have engagement pins 48 on the upper surface.
This engagement pin 48 engages with the engagement elongated hole 49 at the rear end of the lever, and is moved laterally in conjunction with the movement of each lever.

Further, on the lower surface of the lateral slider 40, 41, inverted M-shaped lateral movable contacts 42, 43 equipped with biasing contact springs 50 for promoting contact pressure are installed, and these contact points 42, 43 are attached to the switch case. The switch case 12 slides horizontally on the bottom surface of the switch case 12 and corresponds to these horizontally movable contacts 42 and 43.
A plurality of rear fixed contacts 44 for fine motor output control are insert-molded in parallel on the rear bottom surface of the motor.

In this case, the first lateral slider 40fIII is set to the motor forward rotation side, the second lateral slider 41 side is set to the motor reverse rotation side, and at the initial stroke stage of the straight slider 28, these lateral slider 4041 side By making the contact portions face each other, the motor is configured to output a minute torque.

The above-described motor forward/reverse switching RJH 20 is constructed by installing a forward/reverse switching lever 51 inside the switch case 12 for selectively switching the motor between the forward rotation side and the reverse rotation side. The lever 51 has a pivot hole 5 formed in the printed circuit board 17 with an upright pin 52 protruding from the top surface.
3, and is allowed to rotate about this pivot point as a rotation fulcrum,
Further, the above-mentioned common fulcrum pin 47 is vertically provided on the lower surface corresponding to directly below this upright pin 52, and this common fulcrum pin 47 is connected to both intersecting holes where the first and second direction conversion levers 38 and 39 intersect. 46 to support both levers 38 and 39.

Further, the pin 37a of the operating pin 37 is inserted into a triangular pin holding hole 54 opened in one extending portion of the forward/reverse switching lever 51.
This switching lever 51
The actuating pin 37 is laterally moved by the tilting operation, and the first
- By making it correspond to either one of the second direction conversion levers 38 or 39, the rotation direction of the motor, normal rotation or reverse rotation, can be selected and switched.

A side lever 55 is provided protruding from the side surface of the forward/reverse switching lever 51, and this side lever 55 extends outward from the side opening 57 of the switch case 12 through a side sealing material 56 for dustproofing. The side lever 55 is protruded so that the side lever 55 can be tilted and operated from the outside.

The above-mentioned switch case 12 is provided in a box shape with an open top surface, and the fixed contacts 30, 44 are inserted into the bottom of the case, and the terminals 22 are inserted into the end of the gate. The switching mechanism 18, the motor fine output control 81 horizontally 19, and the motor forward/reverse switching mechanism 20 are housed inside the section 31, and above it are a printed circuit board 17, a transistor support 16, and a power transistor. 14 and the dustproof cover 15 are mounted integrally.

The switch for a DC power tool configured in this way is usually disposed in the grip of the power tool, and is normally attached to the operating lever 13.
is biased by an internal slider return spring 32, so that the operation lever 13, which is provided opposite to the linear slider 28, is in a state in which it is tilted forward from the front surface of the grip portion and can be pressed down using the pivot portion as a fulcrum.

Now, when the operating lever 13 is pushed down against the slider return spring 32, the linear slider 28 that is linked to this lever 13 slides backward, and as a result of this sliding movement, the linear movable contact 29 comes into contact with the front fixed contact 30. This causes a short circuit, the power is turned on, and the motor starts rotating in the forward direction.

At this time, by adjusting the stroke based on the pressing stroke of the operating lever 13, the operating pin 37 is
pushes one of the first direction change levers 38, and this lever 3
The lateral movement slider 40 that is interlocked with 8 moves laterally, and during this lateral movement, the lateral movement movable contact 42 contacts the rear fixed contact 44 for output control, and a small output is obtained, for example when positioning a screw. It is possible to obtain a very small rotational force that is similar to that shown in Figure 2, further improving work efficiency.

Note that when the operating lever 13 is pressed down to the full stroke, the motor torque is fully opened and a significantly high output is obtained.

On the other hand, when the push-down operation of the operating lever 13 is released, the linear slider 28 receives the return action of the slider return spring 32.
slides back to the front end side and the power is turned off.

In addition, when switching the polarity of the motor to switch between forward and reverse rotation, by moving the side lever 55 of the forward/reverse switching lever 51 to the other side, the actuating pin 37 moves laterally in conjunction with this. The polarity of the motor is switched in accordance with the front end of the direction changing lever on the other side. After this switching, when the operating lever 13 is pressed down, the operating pin 37 via the linear slider 28 moves to the switched fl! ! A predetermined rotational output is obtained by transversely moving the lateral slider on the corresponding side, which corresponds to the front end of the direction conversion lever on the side, and the lateral slider on the original direction conversion lever side does not operate.

As mentioned above, since the lateral slider can be moved laterally in conjunction with the initial sliding motion of the straight slider, it is possible to switch between the contact portions of both sliders in conjunction with the movement of the straight slider. The return spring on the lateral slider side can be omitted, and as a result, it is possible to accurately reduce the number of parts, simplify the structure, and simplify assembly.

In the correspondence between this invention and the configuration of the above-mentioned embodiment, the fixed contact for switching operation of this invention corresponds to the front fixed contact 30 of the embodiment, and similarly, the direction change lever is the first The lateral slider corresponds to the direction conversion lever 38 and the second direction conversion lever 39, the lateral slider corresponds to the first lateral slider 40 and the second lateral slider 41, and the fixed contact for output control is the rear fixed contact. However, the present invention is not limited to the configuration of the above-described embodiment.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is an exploded perspective view of a main part of a switch for a DC power tool, and FIG. 2 is a longitudinal sectional side view of the switch for a DC power tool. 11...Motor control circuit section 12...Switch case 18...Switching tR
Horizontal 19... Motor fine output control mechanism 20... Motor forward/reverse switching mechanism 28... Straight slider 29... Straight moving contact 3
0... Front fixed contact 37... Operating pin 38.3
9... Direction conversion lever 40.41... Lateral movement slider 42.43... Lateral movement movable contact

Claims (1)

[Claims] (1) A switch for a power tool that controls the output of a motor based on a switching operation between contact parts, which is a linear slider for push-down operation that protrudes forward from the switch case and is equipped with a linearly movable contact on the bottom surface. a fixed contact for switching operation which is disposed at the bottom of the switch case and corresponds to contact and separation with the linear movable contact; an actuation pin supported by the linear slider to allow lateral movement; and both pieces intersecting in a scissor-like shape. direction conversion levers each having one front end corresponding to the actuating pin with the intersection of the two direction conversion levers as a tilting fulcrum, and a lateral direction conversion lever that engages with the rear end of each direction conversion lever and is equipped with a lateral movement movable contact on the lower surface. a forward slider, a fixed contact for output control that is disposed at the bottom of the switch case and corresponds to the lateral movement movable contact, and a fixed contact that projects outward from the switch case and that moves the operating pin laterally to control the motor. A power tool switch equipped with a forward/reverse switching lever that selectively switches between the rotation side and the reverse rotation side.