JP3812118B2 - Trigger switch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a trigger switch including a heating element such as an FET or a thyristor and a heat radiating plate.
[0002]
[Prior art]
FIG. 7 is a longitudinal sectional view showing a schematic configuration of a conventional trigger switch used in an electric tool, for example, an electric drill.
[0003]
The trigger switch includes an operation lever (trigger) 50 that is operated to rotationally drive the drill blade, a first switch 51 for starting rotation of a motor that drives the drill blade by a retraction operation of the operation lever 50, And a second switch 52 for rotating the motor at full speed.
[0004]
The first switch 51 includes a fixed contact 54 disposed at an upper portion in the case 53 and a movable piece 57 having a movable contact 56 biased by a coil spring 55 so as to be pressed against the fixed contact 54. In the free position where the operation lever 50 is not retracted, the contact portion 58 on the free end side of the movable piece 57 is biased in the direction of the arrow A by the return spring 59 of the plunger portion 60a of the operation shaft 60. The two contacts 54 and 56 are separated from each other on the upper cam portion 61, and the first switch 51 is off.
[0005]
The second switch 52 includes a fixed contact 62 disposed at a lower portion of the case 53 and a movable piece 65 having a movable contact 64 biased by a coil spring 63 so as to be in pressure contact with the fixed contact 62. In the position, the abutment portion 66 on the free end side of the movable piece 65 rides on the cam portion 67 below the plunger portion 60a of the operation shaft 60, and both the contacts 62 and 64 are separated from each other. The 2 switch 52 is off.
[0006]
When the operation lever 50 is retracted from the free position against the urging force of the return spring 59, the contact portion 58 on the free end side of the movable piece 57 of the first switch 51 is moved above the plunger portion 60a of the operation shaft 60. As shown in FIG. 7, the movable contact 56 rotates to contact the fixed contact 54 and the first switch 51 is turned on, and the power is supplied to the motor. Start. Further, a brush (not shown) mounted on the plunger portion 60a of the operation shaft 60 slides on a resistor on a circuit board (not shown) according to the retracted amount of the operation lever 50, and corresponds to the sliding position. The electric current is supplied to the motor via a rotation control element such as an FET, and the motor rotates at a rotation speed corresponding to the pulling amount of the operation lever 50.
[0007]
Further, when the retracting amount of the operation lever 50 reaches a predetermined amount, the abutment portion 66 on the free end side of the movable piece 65 of the second switch 52 moves over the cam portion 67 below the plunger portion 60a of the operation shaft 60 and moves. The contact 64 rotates to contact the fixed contact 62 and the second switch 52 is turned on. The motor and the power supply are short-circuited to rotate the motor at full speed.
[0008]
On the other hand, when the retracting of the operating lever 50 is released, the operating shaft 60 is moved in the direction of the arrow A by the return spring 59, and the operation reverse to the time of retracting is performed. 51 is turned off and the supply of power is cut off. Further, a brake switch (not shown) is turned on and both ends of the motor are short-circuited so that the motor is braked.
[0009]
When reverse rotation is selected by a switching lever (not shown) for switching between normal and reverse rotation, the connection state is switched, and the motor is reversely rotated in the same manner as described above.
[0010]
[Problems to be solved by the invention]
However, in the trigger switch of such a conventional example, a heat radiating plate for radiating heat generated from a heat generating element such as a FET for rotation control is tightly fixed to the heat generating element by tightening a screw. Therefore, the assemblability is poor and there is a problem that a screw for fastening is required.
[0011]
The present invention has been made in view of the above-described points, and a mounting structure capable of closely fixing a heat radiating plate to a heating element without using a fastening member such as a screw, and a trigger using the same The object is to provide a switch.
[0012]
[Means for Solving the Problems]
The present invention is configured as follows in order to achieve the above-described object.
[0016]
That is, the trigger switch of the present invention is a trigger switch including a switch for connecting a power source and a motor in accordance with an operation of an operation lever , a heat generating element, and a heat radiating plate for radiating heat generated by the heat generating element. A plate is bent to form opposing clamping surfaces, a heating element is clamped and attached between the clamping surfaces, and the heat dissipation plate has a terminal portion connected to the motor and a fixed contact portion of the switch It also serves as a conductive member.
[0017]
Furthermore, the trigger switch of the present invention includes an operation shaft that is linked to the operation lever, a return spring that urges the operation shaft to return to a free position, and a cam portion that is provided on the operation shaft. The switch for connecting to the movable piece is rotatable about a fulcrum on one end side and having a movable contact on the other end side, a fixed contact facing the movable contact, and the movable piece to the fixed contact and a biasing member for urging in a direction to press the said movable piece, on the side opposite to the fixed contact a between the fulcrum and the movable contact, contacting the cam portion abutting And the cam portion comes into contact with the abutting portion on the side of the movable piece facing the fixed contact in response to the return movement of the operation shaft to the free position, thereby moving the movable contact from the fixed contact. It is something to break apart .
[0020]
According to the trigger switch of the present invention, the heat sink is bent to form an opposing clamping surface, and the heating element is clamped between the clamping surfaces. And the tightening screw becomes unnecessary.
[0021]
Further, according to the trigger switch of the present invention, since the heat sink is also used as a conductive member having a terminal portion connected to the motor and a fixed contact portion of the switch, it is possible to reduce the number of parts and save space. Can be achieved.
[0022]
Furthermore, according to the trigger switch of the present invention, a movable contact is provided on one end side of the movable piece, a fulcrum is provided on the other end side, and a contact portion that contacts the cam portion of the operation member is disposed therebetween. Therefore, the distance between the movable contact and the contact portion on which the cam portion acts is compared with a so-called double-armed configuration in which the movable contact and the contact portion are arranged on both sides of the fulcrum as in the conventional example described above. When the contact is welded and the contact is welded, it can be forcibly dissociated with a low load.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0024]
1 and 2 are longitudinal sectional views showing different operation states of a trigger switch according to one embodiment of the present invention.
[0025]
The trigger switch 1 includes an operation lever (trigger) 2 that is operated to rotationally drive the drill blade, and a first switch 3 that starts rotation of a motor that drives the drill blade by a retraction operation of the operation lever 2. And a second switch 4 for rotating the motor at full speed. Both switches 3 and 4 are juxtaposed along the thickness direction of the case 5 (perpendicular to the paper surface). The respective contacts constituting the switches 3 and 4 are shown in an overlapping state.
[0026]
The operation lever 2 is provided with an operation shaft 6 as an operation member interlocked with the operation lever 2, and this operation shaft 6 has a plunger portion 6 a, and an arrow A in the figure by a return spring 7. Return biased in the direction.
[0027]
The first and second switches 3 and 4 are juxtaposed along the thickness direction of the case 5 (perpendicular to the paper surface) at a position below the plunger portion 6a of the operation shaft 6, and the first switch on the front side 3 includes a fixed contact 8 disposed in the upper portion and a movable piece 10 urged by a coil spring 9. The second switch 4 on the back side includes a fixed contact 11 disposed in the upper portion and a coil spring 12. The movable pieces 10 and 13 are supported so as to be rotatable around fulcrums 16 and 17 on one end side.
[0028]
In this embodiment, each of the movable pieces 10 and 13 has movable contacts 14 and 15 on one end side so that the forced separation when the contacts are welded can be performed with a low load. 14 and 15 and the fulcrums 16 and 17 on the other end side have curved contact portions 18 and 19, and the movable contacts 14 and 15 are pressed against the fixed contacts 8 and 11 by the coil springs 9 and 12. It is energized in the direction to do.
[0029]
The operation shaft 6 is urged to return in the direction of the arrow A by the return spring 7 as described above. The operation shaft 6 is a circuit board (not shown) according to the operation amount (retraction amount) of the operation lever 2. And a plunger portion 6a equipped with a brush (not shown) that slides on the resistor, and the lower surface side of the plunger portion 6a includes first and second plungers 6a according to the retraction operation of the operation shaft 6. The pressing of the movable pieces 10 and 13 of the second switches 3 and 4 against the abutting portions 18 and 19 is released, and the movable contacts 14 and 15 are connected to the fixed contacts 8 and 15 of the first and second switches 3 and 4, respectively. 11 has first and second cam portions 20 and 21 for sequentially press-contacting to 11. The first and second cam portions 20 and 21 turn on the first switch 3 when the operation lever 2 is operated to the first operation position, and further when the operation lever 2 is operated to the second operation position. The two switches 4 are formed to have different lengths along the moving direction of the operation shaft 6 (left and right direction in the figure) so that the switch 4 is turned on.
[0030]
In the free position where the operation lever 6 is not retracted, the contact portions 18 and 19 of the movable pieces 10 and 13 are biased in the direction of the arrow A by the return spring 7, and the plunger portion 6 a of the operation shaft 6. The first and second cam portions 20 and 21 are pressed down to separate the contacts 14, 8; 15, 11 and the first and second switches 3 and 4 are both turned off.
[0031]
As shown in the circuit configuration diagram of FIG. 3, the trigger switch 1 is used to move the operation shaft 6 interlocked with the operation lever 2 that is pulled in with fingers to rotate the drill blade. Accordingly, the AC power source 22 and the AC motor 23 are connected via a thyristor 25 as a heating element controlled by a control circuit 24 for controlling the rotational speed, and the second switch 4 pulls in the operation lever 2. When the amount exceeds a predetermined amount, the AC power source 22 and the AC motor 23 are short-circuited to rotate the AC motor 23 at full speed. In FIG. 3, 26 and 27 are input terminals connected to the AC power supply 22, and 28 and 29 are output terminals connected to the AC motor 23.
[0032]
Next, the operation of the trigger switch 1 having the above configuration will be described.
[0033]
First, for example, in the free rotation position in the normal rotation state, the operation shaft 6 is in the initial position shown in FIG. 1 by the urging force of the return spring 7, and in this free position, the plunger portion 6a of the operation shaft 6 has the first position. The first and second cam portions 20 and 21 press the curved contact portions 18 and 19 of the movable pieces 10 and 13 against the urging force of the coil springs 9 and 12, respectively. The movable contacts 14 and 15 of 3 and 4 are separated from the corresponding fixed contacts 8 and 11, respectively, and the first and second switches 3 and 4 are in an OFF state. That is, in the free position, both the first and second switches 3 and 4 are off.
[0034]
When the operating lever 2 is pulled from this free position with a finger, the operating shaft 6 moves accordingly in the left direction of FIG. 1 (the direction opposite to the direction of the arrow A), and as shown in FIG. The first cam portion 20 below the plunger portion 6 a of the shaft 6 is separated from the abutting portion 18 of the movable piece 10, and the movable contact 14 of the first switch 3 is moved to the corresponding fixed contact 8 by the biasing force of the coil spring 9. The first switch 3 is turned on, the current flows from the AC power source 22 to the AC motor 23, the drill blade starts to rotate, and the plunger 6a of the operation shaft 6 is equipped according to the retracted amount of the operation lever 2. The brush thus slid on the resistor of the circuit board, and a current corresponding to the sliding position is supplied to the AC motor 23 via the thyristor 25 controlled by the control circuit 24, and the operation lever 2 pulls AC motor 23 at a rotation speed corresponding to the observed amount of rotation.
[0035]
When the operation lever 2 is further retracted to reach a predetermined retracting amount, the second cam portion 21 below the plunger portion 6a of the operation shaft 6 is separated from the contact portion 19 of the movable piece 13, and the coil spring 12 is attached. The movable contact 15 of the second switch 4 is pressed against the corresponding fixed contact 11 by the force, the second switch 4 is turned on, the AC motor 23 and the AC power supply 22 are short-circuited, and the AC motor 23 rotates at full speed. It will be.
[0036]
On the other hand, when the pull-in operation of the operation lever 2 is released, the operation shaft 6 integrated with the operation lever 2 is moved back in the direction of the arrow A by the biasing force of the return spring 7 and is movable by the second cam portion 21 of the plunger portion 6a. When the abutting portion 19 of the piece 13 is pressed against the urging force of the coil spring 12, the movable contact 15 of the second switch 4 is separated from the corresponding fixed contact 11 and the second switch 4 is turned off and further returned. The contact portion 18 of the movable piece 10 is pressed against the urging force of the coil spring 9 by the first cam portion 20 of the plunger portion 6a, and the movable contact 14 of the first switch 3 is separated from the corresponding fixed contact 8. The first switch 3 is turned off and the supply of power is cut off. Further, a brake switch (not shown) is turned on and both ends of the AC motor are short-circuited so that the AC motor 23 is braked.
[0037]
When reverse rotation is selected by a switching lever (not shown) for switching between normal and reverse rotation, the connection state is switched, and the motor is reversely rotated in the same manner as described above.
[0038]
In this embodiment, each of the movable pieces 10 and 13 of the first and second switches 3 and 4 has movable contacts 14 and 15 on one end side as described above. Since there are contact portions 18 and 19 that contact the first and second cam portions 20 and 21, respectively, between the side fulcrums 16 and 17, both sides of the fulcrums 68 and 69 are provided as in the conventional example of FIG. Compared to the so-called double-armed movable pieces 57 and 65 having movable contacts 56 and 64 and contact portions 58 and 66, the contact portions 18 and 15 on which the movable contacts 14 and 15 and the cam portions 20 and 21 act are provided. It is possible to shorten the distance between the contact portion 19 and the contact portion 18, when the contact portion is welded, the contact portion 18, the first and second cam portions 20, 21 of the plunger portion 6 a When pressing 19 to force separation, it is possible to separate with a lower load than before. To become.
[0039]
In this embodiment, the first and second switches 3 and 4 are not arranged above and below the case 5 as in the prior art, but on one side, in this embodiment, on the lower side. Therefore, it is possible to reduce the size and improve the assemblability.
[0040]
Furthermore, in this embodiment, the heat radiating plate for dissipating the heat generated by the thyristor 25 as a heat generating element is attached as follows instead of being attached to the heat generating element by tightening with screws as in the prior art.
[0041]
4 is a perspective view showing details of the mounting state of the heat sink and thyristor of the trigger switch 1 of FIG. 1, FIG. 5 is a perspective view seen from the back side, and FIG. 6 is a heat sink. It is a perspective view which takes out and shows a thyristor.
[0042]
The heat dissipation plate 30 of this embodiment has a side surface portion 34 extending along the side surface of the case 5 of the trigger switch 1 and a back surface portion 35 extending along the back surface of the case 5, and further sandwiches and fixes the thyristor 25. In order to achieve this, it has a sandwiching portion 33 that is bent from a part of the side surface portion 34 so as to face the side surface portion 34, and the sandwiching portion 33 is curved so as to press the thyristor 25. The thyristor 25 is configured to be in close contact and fixed by the spring force.
[0043]
Thus, since the thyristor 25 is clamped and fixed between the opposing clamping surfaces of the heat radiating plate 30, it is not necessary to tighten and fix with screws as in the conventional example, and the assemblability is improved and a screw for tightening is provided. It becomes unnecessary.
[0044]
Furthermore, in this embodiment, the heat radiating plate 30 is not a mere heat radiating plate but also serves as a conductive member, and is connected to one end of the AC motor 23 shown in the circuit configuration diagram of FIG. 3 described above. A connection portion 31 connected to a circuit board constituting the control circuit 24, a connection portion 32 to which the anode of the thyristor 25 is soldered, and a fixed contact 11 of the second switch 4, and an output terminal 29 The connection portions 31 and 32 and the fixed contact 11 of the second switch 4 are also used.
[0045]
That is, a connection part 31 to be soldered to the circuit board and a connection part 32 to which the anode of the thyristor 25 is soldered are formed on the side surface part 34 of the heat radiating plate 30. And the fixed contact 11 of the second switch 4 bent from the back to the inside of the case 5 is formed.
[0046]
Thus, since the heat sink 30 is also used as the output terminal 29, the fixed contact 11, and the connection portions 31 and 32, the number of parts can be reduced, the assemblability can be further improved, the cost can be reduced, and the space can be saved. Can be achieved.
[0047]
In addition, the heat sink 30 does not need to use all of the output terminal 29, the fixed contact 11, and the connection parts 31 and 32, and may use only at least one.
[0048]
In the above-described embodiment, the movable contacts 14 and 15 of the first and second switches 3 and 4 are urged by the coil springs 9 and 12 so as to contact the fixed contacts 8 and 11. As another embodiment, each movable contact of the first and second switches may be urged away from each fixed contact, and the movable piece may be pressed and brought into contact with the cam portion of the plunger portion of the operation shaft. Good.
[0049]
In the above-described embodiment, the present invention is applied to the trigger switch of the AC power source and the AC motor. However, the present invention may be applied to the trigger switch of the DC power source and the DC motor, and is not limited to the trigger switch. Of course, it may be applied to a switch.
[0050]
【The invention's effect】
As described above, according to the trigger switch of the present invention, the heat sink is bent and the opposing holding surfaces are formed, and the heating element is held between the holding surfaces, so that it is fastened with screws as in the conventional example. As a result, it is not necessary to use a screw for tightening, and the heat sink is also used as a conductive member having a terminal part connected to the motor and a fixed contact part of the switch . In addition, the number of parts can be reduced to reduce costs, and space can be saved.
[0052]
Furthermore, according to the trigger switch of the present invention, a movable contact is provided on one end side of the movable piece, a fulcrum is provided on the other end side, and a contact portion that contacts the cam portion of the operation member is disposed therebetween. Therefore, as compared with the so-called double-armed conventional example, the distance between the movable contact and the contact portion on which the cam portion acts becomes short, and when the contact is welded, it can be forcibly dissociated with a low load.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a trigger switch according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view corresponding to FIG. 1 in a different operation state.
3 is a circuit configuration diagram of FIG. 1. FIG.
4 is a perspective view showing details of a mounting state of the heat radiating plate and the thyristor of FIG. 1; FIG.
FIG. 5 is a perspective view corresponding to FIG. 4 as viewed from the back side.
FIG. 6 is a perspective view showing a mounting state of the heat sink and the thyristor.
FIG. 7 is a cross-sectional view of a conventional example.
[Explanation of symbols]
2 Operation lever 3 First switch 4 Second switch 6 Operation shafts 8 and 11 Fixed contacts 10 and 13 Movable pieces 14 and 15 Movable contacts 16 and 17 Support points 18 and 19 Abutment portions 20 and 21 First and second cam portions 22 AC power supply 23 AC motor 25 Thyristor 30 Heat sink

Claims (2)

In a trigger switch including a switch for connecting a power source and a motor according to operation of an operation lever, a heating element, and a heat radiating plate for radiating heat generated by the heating element,
The heat sink is bent to form opposing clamping surfaces, the heating elements are clamped and attached between the clamping surfaces , and the heat sink is connected to a terminal portion connected to the motor and a fixed contact portion of the switch A trigger switch, which is also used as a conductive member having a contact . An operation shaft interlocked with the operation lever, a return spring for urging the operation shaft to return to a free position, and a cam portion provided on the operation shaft,
The switch for connecting the power source and the motor is rotatable about a fulcrum on one end side and having a movable contact on the other end side, a fixed contact facing the movable contact, and the movable piece and a biasing member for urging in a direction which presses the fixed contact, the movable piece, on the side opposite to the fixed contact a between the fulcrum and the movable contact, those with the cam portion Having an abutting portion that contacts,
The cam portion abuts on the abutting portion on a side of the movable piece facing the fixed contact in accordance with a return movement of the operation shaft to a free position, and separates the movable contact from the fixed contact. 1 trigger switch.

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