JPH01130438A - Switch for motor driven tool - Google Patents

Abstract

PURPOSE:To simplify and miniaturize the assembly by furnishing movable contact, pieces for shortcircuiting contacts selectively to constitute two slide type switches, and pressing each slider in a certain direction by a return spring. CONSTITUTION:A band-shaped switch base 32 is furnished in a switch case 13, and a plurality of contacts are formed in parallel with this switch base 32, whereon movable contact pieces 33, 34 retained by sliders 37, 36 for shortcircuiting the contacts selectively are furnished to constitute tm slide type switches A, B, These sliders 37, 38 are pressed in a certain direction by return springs 39, 40. The slider 37, 38 of either slide type switch A, B is slided against the return spring 39, 40 interlocked with the control lever 12 of a motor driven tool, and thereby the contacts are shortcircuited by movable contact pieces 33, 34 to supply current to the motor. This accomplishes small sized construction and enhancement of the efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of the Invention 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. The present invention relates to a switch having a disk contact structure.

Background of the Invention Usually, this type of power tool switch is a two-pole change-over switch, and is used to control the motor's 0N-OF or F1 motor's arbitrary number of rotations, or to switch between forward and reverse rotation. Furthermore, in order to realize a sudden stop when the motor stops, there are several contact mechanisms that have independent functions. For example, a rotary type monitor is used in which the polarity of the motor is changed by rotating a control knob to rotate the monitor in the forward or reverse direction.

However, the presence of a large number of contact mechanisms as described above increases the number of internal components of the switch and complicates the structure.
There was a limit to the ease of assembly and miniaturization.

(c) Purpose of the Invention The present invention provides a compact switch for power tools that can control circuit power ON/OFF, motor forward/reverse rotation switching, and brake contact using a single contact mechanism with a disc structure. purpose.

(D) Structure of the Invention This invention provides a strip-shaped switch board part inside a switch case, a plurality of contacts are formed in parallel on this switch board part, and is held on the upper part of the switch board by a slider. This is a power tool switch in which a movable contact piece that selectively shorts between contacts is provided to form two slide type switch parts, and each slider is biased in a predetermined direction by a return spring. Features.

(e) Effect of the Invention According to the present invention, by interlocking with the operation lever of the electric tool, the slider of one of the slide type switch parts is slid against the return spring, so that the movable contact piece can open the contact. It is possible to short-circuit the motor and allow current to flow through the motor.

(f) Because of the effect of the invention, one of the two slide type switch parts is used for forward rotation of the motor, and the other is used for reverse rotation of the motor, and each has a contact structure that has a power ON/OFF II function for supplying current to the motor and a brake function. As a result, circuit power 0N-OFF, motor forward/reverse rotation, and braking can be performed in one switch structure, and by combining these functions, the structure is simple, low cost, and can be made smaller by electric workers. can.

In addition, since the switch part is formed by randomly hitting the strip-shaped switch board part provided with contacts, the movable pieces on the board, and the slider in a plane, the switch part becomes a compact disc type, and the assembly efficiency is improved.

(g) Examples of the invention An embodiment of the present invention will be described below with reference to the drawings.

The drawings show a DC power tool switch used in a DC motor control circuit. In FIGS. 1 to 3, this DC power tool switch is connected to a control circuit section 11 of a DC motor (not shown).
, an operating lever 12 for driving and operating the motor, and a switch case 13 that integrally supports these,
This is used, for example, by being incorporated into the grip of a power tool such as an electric screwdriver.

The above-mentioned control circuit section 11 includes a power transistor 14,
A heat radiation cover 15 that covers the power transistor 14 from above, a printed circuit board 17 on which a control circuit is mounted, a resistor board 18 provided as a part of the variable reference voltage generator, and a resistor in fixed correspondence with the resistor board 18. It is composed of a brush 19 that changes the value, an insulating housing 20, and a return spring 21 of this movable housing 20.

The power transistor 14 described above has a rectangular shape, and the three terminals 22 protruding from the side surface thereof are bent downward and connected to power terminals 43, 44 and motor terminals 46, 47, which will be described later. and set the armature circuit of the DC motor to 0.
N-OFF control.

The upper heat dissipation cover 15 has a box shape with an open bottom surface, and is integrally mounted on the switch case 13 so as to surround the printed circuit board 18 with the power transistor 14 fixed therein using screws 23.

The above-mentioned printed circuit board 17 is fixedly supported on the switch case 13.

Further, a terminal connection hole 24 is formed in one end of the substrate 17, and power terminals 43 and 44 and motor terminals 46 and 47, which will be described later, are connected to this hole.

A thin resistance board 18 on which a resistance element for generating a variable reference voltage for the motor is printed is attached to the lower surface of the printed circuit board 17.

The above-mentioned movable housing 20 is provided in a box shape that can be stored in a switch case 13, which will be described later.A recessed part 20a in the housing sliding direction is stepped in the center of the upper surface of this cylindrical shape, and a horizontal rotation arm can be attached here. 24 is the fulcrum 2 on the front end side
5 and a cam pin 26 on the upper surface of the rear end.
will be erected.

Similarly, a brush 19 is attached to one side of the concave portion 20a on the upper surface of the housing and slides into contact with the resistance board 18 attached to the lower surface of the printed circuit board 17, so that the brush 19 slides integrally with the movable housing 20. By displacing the contact position with the resistance board 18, the resistance value for torque control of the motor is changed, and the torque of the motor is changed.

Note that the brush 19 is usually attached to the movable housing 20 together with the movable housing 20.
It is biased towards the - side and is set to have the maximum resistance value on the - side and the minimum resistance value on the other side.

Furthermore, a spring seat hole 27 is formed on the rear end side of the lower surface of the movable housing 20, one end of the return spring 21 is inserted into this spring seat hole 27, and the other end is inserted behind the switch case 13, which will be described later. The movable housing 20 is biased forward by the biasing action of the return spring 21, which is inserted and locked onto the front surface of the contact cover 28 provided on the end side, and which is normally stored in a compressed state. be.

Further, the lower front end side of the movable housing 20 is provided with an operating shaft engagement hole 30 into which an operating shaft 29 of the operating lever 12 (described later) is inserted, so that the operating lever 12 can be pressed down through the operating shaft 29. Accordingly, the movable housing 20 is
Slide operation is performed in the front and rear directions.

The above-mentioned switch case 13 is provided in a box shape with an open top surface, and the above-mentioned movable housing 20 is housed inside this top surface opening 31 while being allowed to slide in the front-rear direction, and a printed circuit board 17 and a power transistor 14 are placed above the movable housing 20 . , and a heat dissipation cover 15 are mounted, and these are mounted in one body.

Furthermore, a switch board portion 32 for forward/reverse switching is formed on the rear side of the upper opening 31. This switch board section 32
A pair of left and right movable contact pieces 33 and 34 each held by a slider 37 and 38 are placed on the top so as to be able to slide in the lateral direction, and the switch board portion 32 and the movable contact piece 33
, 34 are covered with a contact portion cover 28.

Guide holes 35 and 36 for guiding the sliding of the movable contact pieces 33 and 34 are formed on the upper surface of the contact part cover 28, and slider pins 37a and 38a that are integrally planted on the sliders 37 and 38-1 are inserted downward into these holes. It's coming out upwards. The movable contact pieces 33 and 34 each have a return spring 39.40.
Therefore, the slider pin 35.
36 normally contacts one end of each adjacent side of the guide hole 35, 36 as shown in FIG.

The slider 37, the movable contact piece 33, and the switch board part 32 constitute one slide type switch part A, and the slider 38, the movable contact piece 34, and the switch board part 32 constitute the other slide type switch part B.

A fulcrum pin 16 is erected on the contact portion cover 28 at a position rearward of the guide holes 35 and 36, and a forward/reverse switching lever 42 is attached to this by fitting into the pin hole 42. This I
The F reverse switching lever 41 is formed into a battledore shape on the front side with the pin hole 42 in between, and the above-mentioned slider pins 37a, 3
8a to the movable housing 20 side, and a substantially mountain-shaped cam groove 42 is provided in the battledore portion 41a when viewed from above, and the cam pin 26 of the horizontal rotation arm 24 is inserted into this cam groove 42 from below to above. It is pulled out and engaged. The substantially mountain-shaped cam groove 42 has two cam groove portions 42a and 42b that approach from the bottle hole 42 side toward the cam pin 26 side.

In addition, the rear side of the forward/reverse switching lever 41 across the pin hole 42 is bent upward into a single character shape and has a finger rest part 41b, and as is clear from FIG. 2, the DC power tool switch can be assembled. In the state where the battledore part 41a is
7 and the contact portion cover 28, and the finger hook portion 41b is positioned so as to protrude outside the switch.

As will be clear from the description below, this forward/reverse switching lever 41 is used to select the forward or reverse rotation direction of the motor, and as the movable housing 20 slides, the cam pin 26 of the horizontal rotating arm 24 is moved into the cam groove 42a, 42b, the forward/reverse switching lever 41 rotates around the fulcrum pin 16 and selectively presses one of the slider bins 37a and 38a outward, thereby switching the slide type switch section A or B. Drive.

Furthermore, the next group of terminals are attached to the rear surface of the switch case 13. That is, the first power terminal 43 and the second power terminal 44 are located at the innermost side, and the first motor terminal 46 and the second motor terminal 47 are located with the common terminal 45 in between.

The switch board section 32 has contacts 48 to 53 shown in FIG.
is buried by insert molding, and the first
The power terminal 43 is connected to the NC contacts 50 and 51, the common terminal 45 is connected to the common contact 49, the first motor terminal 46 is connected to the common contact 52, the second motor terminal 47 is connected to the common contact 52, and the above-mentioned movable contact piece 33 is connected to the return spring 39. Common contact 49 and NC at all times with the force of
The contacts 50 are short-circuited, and the other movable contact piece 34 is connected to the return spring 40.
The common contact 52 and the NC contact 51 are normally short-circuited by the force of .

Moreover, the common terminal 45 is connected to the power transistor 14 on the other hand.
Similarly, a second power supply terminal 44 is connected.

The first motor terminal 46 and the second motor terminal 47 are connected to the motor and to the control circuit section 11 on the other hand.

Of course, the first power terminal 43 and the second power terminal 44 are connected to a power source.

Further, in FIG. 4, a switch 54 connected in parallel to the power transistor 14 is for fully opening the motor torque, which is turned on when the movable housing 20 is slid all the way.

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 12.
is biased by an internal spring (not shown), and 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 hole 55 at the lower end as a fulcrum.

Before use, move the forward/reverse switching lever 41 to the finger hook 41.
When the operating lever 12 is pressed down from a state in which it is rotated in the direction of arrow A in FIG. Slide to the right (in Figure 3),
Along with this slide, the horizontal rotation arm 24 on the lever 12
As the cam bin 26 enters one cam Ri portion 42a of the cam 8642 due to the displacement of the forward/reverse switching lever 41, the forward/reverse switching lever 41 is forcibly rotated further in the direction of the arrow A. Therefore, one of the slider bins 37a engaged with the lever 41 is pressed in the same direction, and therefore the slider 37 connected to the slider bin 37a is pushed in the same direction.
The movable contact 33 then slides against the return spring 39 to short-circuit contacts 48 and 49 in FIG.

As a result, the current flows from the first power supply terminal 43 to the NO contact 48 to
Movable contact piece 33 → common contact 49 → first motor terminal 46 →
The flow goes from the DC motor → second motor terminal 47 → common contact 52 → flexible contact piece 34 → NC contact 51 → common terminal 45 → power transistor 14 → second power supply terminal 44, and the power is turned on and the motor rotates in the forward direction. to start.

At this time, by adjusting the stroke based on the pressing stroke of the operating lever 12, the contact position between the brush 19 and the resistance board 18 via the speed change control circuit of the power transistor 14 is shifted, so that the motor torque is is variably controlled and adjusted to a desired output torque suitable for the usage situation of the power tool.

Then, when the operating lever 12 is pressed down to the full stroke, the movable housing 20 slides to the rear end position,
When the switch 54 is turned ON, the collector and emitter of the power transistor 14 in the latter stage of the speed change control circuit are short-circuited, and the motor torque is fully opened, producing high output.

On the other hand, when the pressing operation of the operating lever 12 is released, the movable housing 20 slides toward the surface end due to the returning action of the return spring 21, and the forward/reverse switching lever 41 and the operating lever 12 also return to their original inclined state. However, the movable contact piece 33 interlocked therewith is also returned to its original position by the return spring 39, and as a result, the power is turned off.

In this case, at the same time as the power is turned off, the movable contact piece 33 contacts the original contact 50, and this contact action generates a back electromotive force on the motor side, which rotates due to inertia after the power is turned off. However, this back electromotive force exerts a braking action on the motor to instantly stop the motor from rotating, thereby providing OFF control suitable for operating the power tool.

Furthermore, when the operating lever 12 is pressed down from the state where the forward/reverse switching lever 41 is rotated toward the arrow in FIG. The slider pin 38a for the cam bin 26 to enter the other cam groove 42b is pressed, and the slider 38 and the movable contact piece 34 slide to short-circuit the contacts 52 and 53.

As a result, the current flows from the first power supply terminal 43→No contact 53→
Movable contact piece 34 → common contact 52 → second motor terminal 47 →
The current flows from the DC motor to the first motor terminal 46 to the common contact 49 to the movable contact piece 33 to the NC contact 50 to the common terminal 45 to the power transistor 14 to the second power terminal 44, and as a result of the flow to the motor being reversed, the motor is in the reverse phase. The operation after ΦNOJ is the same as described above.

In this way, the slide type switch part A has the combined functions of switching the motor between forward and reverse directions, turning ON/OFF the power to the motor, and suddenly stopping the motor.

B. It can be implemented with a single switch mechanism consisting of the forward/reverse switching lever 41 and the horizontal rotation arm 24, and the internal structure of the DC power tool switch is greatly simplified.

Moreover, the above member A is inside the switch case 13.

B, 41.24 and the movable housing 18 are the combination 1
Assembling is easy because they are arranged neatly and flatly.

Regarding the correspondence between the structure of this invention and the above-mentioned embodiments, the contacts of this invention correspond to contacts 48 to 53 of the embodiments, but this invention is not limited to the structure of the above-mentioned embodiments. do not have.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an exploded perspective view of the main parts of a switch for a DC power tool, and FIG.
The figure is a longitudinal sectional front view of the DC power tool switch, and FIG. 4 is a control circuit diagram. 12... Operation lever 13... Switch case 20... Movable housing 24... Horizontal IDI l
j Firm 6...Cam pin 28...Contact part cover 32...Forward/reverse switching switch board part 33.3
4...Movable contact piece 37.38...Slider 41...
・Forward/reverse switching lever 42...Cam grooves 42a, 42b
...Cam grooves 48 to 53...Contacts A, B...Slide type switch part -99 etc. Figure 2
・Swift Kasui nazo p12...J Kumei 乍ので- Direct electric telemarketing tool switch, Chi's comfort Kuramasaichi Figure 33.34 ・
・・5th gravity) No./i Figure 4 System wholesale circuit diagram

Claims (1)

[Claims] (1) A strip-shaped switch board part is provided inside the switch case, and a plurality of contacts are formed in parallel on this switch board part, and is held by a slider on the top of the switch board to selectively connect between the contacts. A switch for a power tool in which two slide type switch parts are configured by a short-circuiting movable contact piece, and each slider is biased in a predetermined direction by a return spring.