JPH02312121A - Switch for motor-driven tool - Google Patents

Abstract

PURPOSE:To enhance operation sensing performance by providing a pressure sensing piece for sensing operation of a normal/reverse switch layer adapted to press an operation pin under pressure of a return spring in a space between the return spring for pressing and projecting a linear slider before a switch case and the operation pin. CONSTITUTION:A pressure sensing piece F for sensing the operation of a normal/ reverse switch lever 51 adapted to press an operation pin 37 under pressure of a return spring 32 is provided in a space between the return spring 32 for pressing and projecting a linear slider 28 before a switch case and the operation pin 37. Accordingly, upon switching operation of the normal/reverse switch lever 51, the operation pin 37 is temporarily associated with the pressure sensing piece F during the switching operation, to be laterally advanced against the pressure of the pressure sensing piece F. At this moment, an abrupt fluctuation of the pressure is generated to cause a change in resistance to a lever 13, thus transmitting an apparent operation sensing force to the lever 13. Therefore, the switch can efficiently be provided with an operation sensing function.

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, electric drills, etc. This invention relates to a power tool switch with enhanced operation feel.

(b) Prior Art Usually, this type of power tool switch is used to control the motor's
Several independent contact mechanisms are internally configured for N/OFF operation, arbitrary rotation speed control of the motor, and forward/reverse rotation operation by switching the polarity of the motor.

By the way, when operating the above-mentioned forward/reverse switching lever that switches the polarity of the motor, it is difficult to get a clear feel of the operation when switching, which may lead to a feeling of distrust during the switching operation, resulting in poor operability.
It lacked reliability, and improvements in operational feel were desired.

(c) Problems to be Solved by the Invention This invention provides an electric tool for use in which the return spring of the linear slider is also used as the operating feel member of the forward/reverse switching lever, and the forward/reverse switching lever has an operating feeling function. The purpose is to provide switches.

(D) Means for Solving the Problems This invention provides a linear slider having contacts for motor output control, a lateral slider having contacts for motor output switching, and an operating pin attached to the linear slider. A switch for an electric power tool is provided with a forward/reverse switching lever for laterally moving a transverse slider, the switch comprising: between opposing surfaces of the operating pin and a return spring that urges and protrudes the linear slider forward of a switch case; This is a switch for a power tool that includes a biasing touch piece for operating a forward/reverse switching lever that presses and biases an operating pin in response to the biasing force of a return spring.

(E) Effect of the Invention According to the present invention, when the forward/reverse switching lever is operated to switch, the actuating pin that interlocks with the switching operation temporarily corresponds to the biasing touch piece, and is biased during this response. It will move sideways against the pressing force of the touch piece, and at this time, the strength of the urging force will suddenly change, and the resistance value against the lever will change.
Transmits a clear tactile force to the lever.

(f) Effects of the Invention As a result, the operator of the forward/reverse switching lever can clearly confirm the operating feel during the switching operation, and the operability and reliability of the forward/reverse switching lever can be reliably improved.

In addition, with this tactile force imparting structure, the return spring that returns the linear slider can also be used as a tactile force imparting member, making it possible to effectively utilize the existing return spring. It is possible to reduce the number of parts and increase efficiency (operation tactile functions can be provided).

(g) Examples 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 DC motor control circuit section 11 includes a power transistor 1
4, a dustproof cover 15 that covers each terminal portion of the power transistor 14 from above, a transistor support 16 that holds the power transistor 14, a printed circuit board 17 that carries a control circuit, and a switching device that turns the motor on and off. Mechanism 18 and motor fine output control mechanism 19
and a motor forward/reverse switching mechanism 20.

Among these, the power transistor 14 is formed in a rectangular shape, and three terminals 21 protruding from the side surface thereof are bent downward to connect to a predetermined power supply insert molded in the switch case 12 facing the power transistor 14. Terminal, motor terminal 22
... to turn on and off the armature circuit of the DC motor.
FF control.

The transistor support 16 has the above-mentioned power transistor 14 mounted on the upper surface by caulking with rivets 23, and the lower surface has engagement holes hanging down at the four corners in order to clamp and fix a printed circuit board 17, which will be described later, between the upper surface of the switch case 12 and the upper surface of the switch case 12. Piece 24・
... is engaged with and integrally installed on the switch case 12.

The above-mentioned printed circuit board 17 is clamped and fixed between the upper and lower sides of the transistor support body 16 and the switch case 12, and the above-mentioned dustproof cover 15 is inserted into the engagement hole 25 formed at one end of this board 17. The dustproof cover 15 is attached by engaging the projecting pieces 26, and each terminal connection hole 27 of the board 17 is attached.
. . . are connected to the power terminals and motor terminals 22 . . . described above.

The aforementioned switching mechanism 18 includes a linear slider 28,
It is comprised of a linear movable contact 29 attached to the lower surface and a front fixed contact 30, and is housed in the switch case 12.

The above-mentioned linear slider 28 is housed in the upper opening 31 of the switch case 12 so as to be allowed to move back and forth in the front and rear directions, and the slider is interposed in a compressed state between the inner end surface of the linear slider 28 and the inner end surface of the switch case 12. The extension biasing action of the return spring 32 normally moves the linear slider 28 forward (
(to the right in the figure), this straight slider 28
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. It slides straight ahead, and a front fixed contact 30 for switching operation, which is insert-molded on the front bottom surface of the switch case 12, corresponds to the straight-moving movable contact 29 so as to be able to approach and separate.

The operating lever 13 is attached to the outer end of the push-down shaft 33 described above.
One end of the slider 28 is opposed to the other, and the pressing stroke of the operating lever 13 causes the linear slider 28 to move straight against the slider return spring 32, and at the end of this straight movement, the linear movable contact 29 comes into contact with the front fixed contact 30. and short circuit, from OFF to O
It constitutes a slide type switch that starts the motor when switched to the N state.

By the way, a biasing touch piece F is interposed between the facing surfaces of the linear slider 28 and the slider return spring 32, and this biasing touch piece F has a circular spring seat F1 on the rear end side and a small protrusion on the front end side. Inside the switch, a circular spring seat Fl is biased by the slider return spring 32 and biased against the linear slider 28 on the front end side, and an opening is formed in the opposing portion of the linear slider 28. The biasing touch piece F is attached with the small protrusion F2 fitted into the loose fitting hole 28a, and the lower pin 37b of the actuating pin, which will be described later, is opposed to the tip of the small protrusion F2. It is designed to give a feeling of operation on the side.

The aforementioned motor fine output control mechanism 19 includes an operating pin 37, first and second direction conversion levers 38 and 39, and first and second direction conversion 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 above-mentioned operating pin 37 is provided with an upper pin 37a standing up on the upper surface having a rectangular shape and a lower pin 37b hanging down on the lower surface.
This operating pin 37 is engaged with a lateral movement slide groove 45 formed on the upper surface of the linear slider 28, and a lateral movement allowance hole 45a that is open and communicates with the lower side of this lateral movement slide groove 45 is inserted into the lateral movement allowance hole 45a.
The lower pin 37b is inserted while being allowed to move laterally. At the intersection position where the vertical lateral movement allowance hole 45a and the horizontal loose fitting hole 28a intersect at right angles, the lower pin 37b and the small protrusion F2 are allowed to face each other, and in the process of lateral movement of the operating pin 37, the lower pin 37b becomes the small protrusion. F2
In response to the biasing force, a predetermined resistance change is applied to the actuating pin 37 side, 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 moved above the linear slider 28 with the upper pin 37a of the operating pin 37 interposed from below in a V-shaped space formed between the opposing surfaces on the front side of the levers. For example, one lever 38 receives the pressing force in the straight direction of the actuating pin 37 which is arranged oppositely and moves forward together with the straight slider 28, and the rear side of the one lever 38 is tilted outward with the intersection as a tilting fulcrum. Moves by changing direction laterally. At this time, since the other lever 39 is not subjected to any pressing force, it does not tilt and remains at the original standby position.

On the rear end side of both levers 38 and 39, a first
-The second lateral slider 40.41 is attached.

The above-mentioned lateral slider 40.41 has an engagement pin 48 on the upper surface.
This engagement pin 48 is engaged with the engagement elongated hole 49 at the rear end of the lever, and is moved laterally in conjunction with the movement of the individual levers 38 and 39.

Further, on the lower surface of the lateral slider 40, 41, inverted M-shaped lateral movable contacts 42, 43 with biasing contact springs 50 for promoting contact pressure are installed, and these contact points are connected to the switch. The switch case 12 slides horizontally on the bottom surface, and on the rear bottom surface of the switch case 12, which corresponds to the lateral travel movable contacts 42 and 43, there is a rear fixed contact 44 for controlling the motor fine output.
Multiple pieces are inserted and molded in parallel.

In this case, the first lateral slider 40 side 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 sliders 40. By bringing the contact portions on the 41 side into contact with each other, the motor is configured to output a minute torque.

The motor forward/reverse switching mechanism 20 described above is constructed by installing a forward/reverse switching lever 51 inside the switch case 12 for selectively switching the motor between forward and reverse rotation. The switching lever 51 has a pivot hole 53 formed in the printed circuit board 17 with an upright pin 52 protruding from the top surface.
The above-mentioned common fulcrum pin 47 is provided vertically on the lower surface directly below the upright pin 52, and the common fulcrum pin 47 is perpendicularly supported on the lower surface of the upright pin 52.
7 is inserted into both intersecting holes 46 where the first and second direction changing levers 38.39 intersect, and supports both levers 38.39.

Further, the upper bin 37 of the operating bin 37 is inserted into the triangular pin holding hole 54 opened in one extension of the forward/reverse switching lever 51.
a is allowed to move in a straight line and play, and this switching lever 5
By moving the operating bin 37 laterally with the tilting operation in step 1 and making it correspond to either the first or second direction conversion lever 38 or 39, the rotation direction of the motor, normal or reverse, can be selected. I'm trying to switch between them.

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 insert-molded at the bottom of the case, and the terminals 22 are insert-molded at the ends of the case. The switching mechanism 18, the motor fine output control mechanism 19, and the motor forward/reverse switching mechanism 20 are installed in the section 31, and above the switching mechanism 18, a printed circuit board 17, a transistor support 16, and a power transistor are installed. 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 its full stroke, the motor torque is fully opened and a very 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 operating bin 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 actuating bin 37 via the linear slider 28 corresponds to the front end of the direction change lever on the other side that has been switched, and the lateral slider on the corresponding side A predetermined rotational output can be obtained by performing a lateral movement.

By the way, when the forward/reverse switching lever 51 is switched, the actuating pin 37, which is interlocked via the direction changing lever, temporarily comes into contact with the biasing touch piece F during the switching operation process, and at this time, the lower pin 37b moves forward so as to climb over the tip of the small protrusion F2, and at this time, the strength of the urging force is suddenly increased, and the resistance value against the forward/reverse switching lever 51 changes,
A clear operational feeling force is transmitted to the operator who operates this lever 51.

As mentioned above, the operating feel when switching the lever can be clearly confirmed, and the operability and reliability of this forward/reverse switching lever are definitely improved.In addition, the internal tactile force imparting structure allows the straight slider to return to its original position. The existing slider return spring can also be used as a tactile force imparting member, making effective use of the existing slider return spring, eliminating the need for a new elastic member to impart tactile force, allowing for efficient operation while reducing the number of parts. It can have a tactile function.

In the correspondence between this invention and the configuration of the embodiment described above, the contact for controlling the motor output of the invention corresponds to the linear movable contact 29 of the embodiment, and similarly, the contact for switching the motor output is as follows: Lateral movement movable contact 42.43
The lateral slider corresponds to the first lateral slider 40 and the second lateral slider 41, and the return spring corresponds to the slider return spring 32. It is not limited only to the configuration.

[Brief explanation of drawings]

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. 28... Straight-moving slider 29... Straight-moving movable contact 32... Slider return spring 37... Operating pin 40
．． 41...Transverse movement slider 42.43...Transverse movement movable contact 51...Forward/reverse switching lever F...Biasing touch piece 2nd
figure

Claims (1)

[Claims] (1) A linear slider that has a contact for motor output control, a lateral slider that has a contact for motor output switching, and forward/reverse switching that moves the lateral slider laterally through an operating pin attached to the linear slider. A switch for a power tool comprising a lever, wherein the operating pin is pressed by the biasing force of the return spring between opposing surfaces of the return spring that urges the linear slider to protrude forward of the switch case and the operating pin. A switch for power tools that has a biasing touch piece that allows you to feel when operating the biased forward/reverse switching lever.