JPH05101747A - Trigger switch - Google Patents

Abstract

PURPOSE:To close a break contact surely, to secure the installing distance between a fixed contact terminal and a source contact terminal easily, and to make an external wiring unnecessary, by providing a slider which has a movable contact, to a rotation frequency operating lever. CONSTITUTION:While a slider 48 movable together with a rotation frequency operating lever 38 is provided, a movable contact 14e movable together with the slider 48 is provided, to the operation shaft 40 of the rotation frequency operating lever 38. And the void contact terminal 14b, the fixed contact terminal 14a, the contact terminal 14c for low speed rotation, and the contact terminal 14d for high speed rotation, of a contact 14 for converting rotation frequency, are provides in order in the driction of the retracting operation of the lever 38, positioning at the upper side of the contact 14c, and the terminal 14a is arranged in the condition projecting lower than the other contact terminals. As a result, while the terminal 14b (a brake contact terminal) is short-circuited and closed surely by the contact 14e, the installing distance between the terminal 14a and the terminal 14c, and the like can be secured. Since the contact 14 and a contact for converting the regular and reverse rotation directions can be provided in a single unit, external wiring can be dispensed with.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trigger switch suitable for use in electric tools and the like, and more particularly to improvement of its contact structure.

[0002]

2. Description of the Related Art For example, in an electric drill in which the rotational speed of a drill blade is controlled by the amount of operation of the operation lever of a trigger switch, a DC motor is generally used to drive the drill blade. The rotation speed of the DC motor changes in association with the operation amount, and the drill blade is driven according to the rotation speed.

To facilitate understanding, the electrical structure of the conventional trigger switch will be described with reference to FIG. 7, and the contact structure of the switch will be described with reference to FIG. ..

This trigger switch includes a rotation speed control unit 102 in which a circuit for controlling the rotation speed of the DC motor 100 as shown in FIG. 7 is incorporated, and a circuit for rotating the DC motor 100 in the forward or reverse direction. And a forward rotation / reverse rotation unit 104 in which is incorporated, and both units 102 and 104 are connected by an external wiring 106. And DC power supply 1 mounted on the electric drill
The voltage of 08 is controlled by the rotation speed control unit 102 according to the operation of the trigger switch, and the controlled current is applied to the wiring 1
It is output to the forward rotation / reverse rotation unit 104 via 06, and the forward rotation / reverse rotation unit 104 outputs the current to the DC motor 100 by controlling the polarity of the current. As a result, the DC motor 100 is normally or reversely rotated at a rotation speed corresponding to the operation of the trigger switch, and the drill blade is driven in conjunction with this.

The rotation speed control unit 102 includes a power switch 110, a control circuit 114 including a variable resistor 112, a rotation speed switching contact 116, and a diode 11.
8 and the DC power supply 108 is turned on when the power switch 110 is closed, and a current controlled by a voltage according to the sliding position of the brush 112a of the variable resistor 112 is output via the switching contact 116. It is supposed to do. Here, the switching contact 116 includes a fixed contact terminal a, an empty contact terminal b, a source contact terminal c, a drain contact terminal d, and a movable contact e, and one end of the movable contact e is connected to the fixed contact terminal a, The other end moves on the empty contact terminal b, the source contact terminal c, and the drain contact terminal d. Further, when the fixed contact terminal a and the empty contact terminal b are connected, the power source 108 is not output and the electric drill is in the non-driving state, and the fixed contact terminal a and the source contact terminal c are connected. At this time, the low speed rotation voltage according to the position of the brush 112a is the FET 120.
Output current to the forward / reverse rotation unit 104.
When the fixed contact terminal a and the drain contact terminal d are connected to each other, the power supply voltage is output to the forward / reverse rotation unit 104 side without passing through the FET 120 regardless of the brush position.

Here, the rotation speed control unit 102 shown in FIG.
The mechanical structure of the rotation speed switching contact 116 is shown in FIG. Here, briefly explaining FIG. 8,
The operating shaft 122 of the operating lever is urged in the direction of arrow A by a return spring 126 between the switch rear surface 124 and the electric drill. It is designed to be retracted. In FIG. 8, the contact member 128 is the fixed contact terminal a, the contact member 130 is the source contact terminal c, the contact member 132 is the drain contact terminal d, and the contact member 134.
Corresponds to the movable contact e, respectively.

Contact members 128, 1 corresponding to the fixed contact terminal a, the source contact terminal c, and the drain contact terminal d.
30 and 132 are arranged in this order with a predetermined insulation distance in the AB direction, and the contact member 134 corresponding to the movable contact e is rotatable about a fulcrum 136, and
It is provided so as to be movable in the AB direction. When the front portion of the operation lever is not touched with fingers, that is, in the initial state where the operation lever is not operated, the movable contact e of the rotation speed switching contact 116 is an empty contact as shown in FIG. It is located at terminal b. In FIG. 8, the upper protrusion 134a of the contact member 134 corresponding to the movable contact e is pushed in the direction A by the protrusion 122a of the operation shaft 122 of the operation lever, and is stationary as shown in FIG. is there.

Next, when the operation lever is pulled in the direction of arrow B, the power switch 110 of FIG. 7 is closed in conjunction with this, and the variable resistor 11 of the control circuit 114 is closed.
The second brush 112a slides on the resistance portion (resistor printed on the printed board) 112b, and a current corresponding to the sliding position is applied to the switching contact 116. On the other hand, the protrusion 1 of the contact member 134 corresponding to the movable contact e
34a is released from the movement which was blocked by the projection 122a of the operation shaft 122 of the operation lever in association with the pulling operation of the operation lever.
By 38, the contact member 134 corresponding to the movable contact e rotates clockwise around the fulcrum 136, and the contact member 134 contacts the contact member 128 (corresponding to the fixed contact terminal a) and the contact member 13.
0 (corresponding to the source contact terminal c), so that in FIG. 7, the fixed contact terminal a and the source contact terminal c
And are connected.

When the operating lever is further pulled in the direction of the arrow B to move the operating shaft 122 in the same direction, the contact member 134 is moved in the direction of the arrow B, and as a result, the contact member 134 is moved to the contact member 128. It comes into contact with 132, which causes the fixed contact terminal a in FIG.
And the drain contact terminal d are connected.

[0010]

By the way, in an electric drill, when the drilling is stopped halfway through the drilling of the workpiece, or when the drilling is finished, remove the fingers from the operating lever and use the DC motor. It is necessary to stop the rotation of. However, the DC motor cannot be stopped rapidly due to mechanical inertial force, and as a result, the workpiece may be unnecessarily drilled. In order to eliminate this, it is necessary to forcibly stop the DC motor against the inertial force.Therefore, a brake contact is provided in parallel with the DC motor and the brake contact is released at the same time when the operation lever retract operation is stopped. Many proposals have been made for closing the DC motor so that the DC motor is braked.

By the way, in the above trigger switch, first of all, for example, the contact member 128 corresponding to the fixed contact terminal and the contact member 1 corresponding to the source contact terminal.
In order to prevent the insulation between both members from being destroyed by a high voltage applied to 30 and short-circuiting, it is necessary to insulate them by a predetermined distance,
Secondly, immediately after the operating lever is pulled in from the initial state, the fixed contact terminal, for example, the member 128 and the source contact terminal, for example, the member 130 are connected to rotate the DC motor 100 and suddenly drive the drill blade to rotate. If this is done, the operation becomes inconvenient. Therefore, after performing a stroke operation related to a certain play on the operation lever, the members 128, 130 are operated.
There is an operational requirement that the drill blade be connected and the drill blade be rotationally driven.

Therefore, the above-mentioned conventional trigger switch has a structure satisfying such requirements. However, when a brake contact is to be provided in the DC motor, when the finger is released from the operation lever, In addition, the structure is such that the brake contact is closed securely, for example, even if the insulation distance between the contact member 128 corresponding to the fixed contact terminal and the contact member 130 corresponding to the source contact terminal is secured, the structure is thereby provided. There is a problem that it does not become large. Furthermore, the rotation speed control unit 102 and normal rotation
Since it is necessary to connect the reversing unit 104 with the external wiring 106, the wiring work is not only troublesome, but also the structure becomes complicated, so there is a problem of eliminating the need for the external wiring 106.

Therefore, in the present invention, when the brake contact is provided in the DC motor, the structure is such that the brake contact is surely closed, and the insulation distance between the fixed contact terminal and the source contact terminal can be easily secured. And a trigger switch having a structure that does not require external wiring.

[0014]

In order to achieve such an object, in the trigger switch according to claim 1 of the present invention, the operation shaft of the rotation speed operation lever is movable integrally with the operation lever. A slider is provided, the slider is biased upward, and a movable contact is provided so as to be movable integrally with the slider while being pressed against the slider. An empty contact terminal, a fixed contact terminal, a low-speed rotation contact terminal, and a high-speed rotation contact terminal for the rotation speed switching contact are arranged sequentially in the pull-in operation direction, and the fixed contact terminal is located below the other contact terminals. When the rotation speed control lever is not operated, the empty contact terminal and the fixed contact terminal are short-circuited by the movable contact when the rotation speed operation lever is not operated. It is connected in parallel to serve as a brake contact terminal for the DC motor, and when the rotation speed operation lever is retracted, the movable contact moves with the movement of the slider, and the movable contact moves to a fixed contact terminal at a predetermined movement position. By moving the seesaw operation away from the empty contact terminal, the fixed contact terminal and the contact terminal for low speed rotation are contact short-circuited, and further, the movable contact is moved to the fixed contact terminal by the movement of the movable contact accompanying the pulling operation. It is characterized in that the contact terminal for high speed rotation is contact short-circuited.

In the trigger switch according to the second aspect of the present invention, the forward contact terminal for one of the forward / reverse rotation switching contact and the other positive contact are integrally formed with the empty contact terminal by the first contact terminal member. Forming a reversing contact terminal of the reversing / reversing switching contact, and integrally forming a fixed contact terminal with the second contact terminal member, one of the reversing contact terminal of the reversing / reversing switching contact and the other Forming a forward rotation contact terminal of the forward rotation / reverse rotation switching contact of, and a fixed contact terminal of one forward rotation / reverse rotation switching contact and the other of the third and fourth contact terminal members, respectively. Fixed contact terminals for the forward / reverse switching contact are respectively formed, and the first and second contact terminal members are arranged to face each other, while the third and fourth contact terminal members are provided to the first and second contact terminals. The members are arranged opposite to each other with the member in between, and this can be It is characterized by short-circuiting the Luo each contact terminal members to each other.

[0016]

According to the first aspect of the present invention, the movable contact is pressed upward by the slider, and the fixed contact terminal is provided so as to project downward from the other contact terminals. In a state where the empty contact terminal and the fixed contact terminal are short-circuited by the movable contact as the brake contact of the DC motor during non-operation, the short-circuiting is surely performed.

When the rotation speed operating lever is pulled in, the movable contact moves with the movement of the slider, and the movable contact performs a seesaw operation at the fixed contact terminal at a predetermined moving position. By this, until the fixed contact terminal and the contact terminal for low speed rotation come into contact with each other, it is possible to easily secure a stroke for the operation of the operation lever.

According to another aspect of the present invention, the first contact terminal member includes an empty contact terminal, a forward rotation contact terminal of one of the forward rotation / reverse rotation switching contacts and a reverse rotation contact terminal of the other forward rotation / reverse rotation switching contact. In addition, the second contact terminal member serves as a fixed contact terminal, a reversing contact terminal of one forward rotation / reverse rotation switching contact and a forward rotation contact terminal of the other forward rotation / reverse rotation switching contact. Since they are also used, the rotation speed switching contact and the forward / reverse rotation switching contact can be provided not in separate units but in one unit. By providing a contact for use, the external wiring connecting each unit becomes unnecessary.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing an electric circuit configuration in the rotation speed / forward / reverse rotation unit achieved by the trigger switch of this embodiment. As shown in FIG. In contrast to the conventional unit, the unit is not divided into a rotation speed control unit and a forward / reverse rotation unit, but they are integrated units, which makes external wiring unnecessary.

That is, in the figure, 2 is a DC power source mounted on an electric drill as an electric tool to which the embodiment is applied, and 4 is a DC motor for driving a drill blade. A rotation speed / forward / reverse rotation unit 6 is provided between the DC power supply 2 and the DC motor 4.

In the rotation speed / forward / reverse rotation unit 6,
8 is a power switch, 10 is a control circuit, 12 is a FET, 1
4 is a rotation speed switching contact, 16 is a diode, 18, 20
Are a pair of forward / reverse rotation switching contacts that are interlocked with each other. 22a and 22b are input terminals of the unit 6,
Similarly, 24a and 24b are output terminals of the unit 6.

The control circuit 10 has a variable resistor 2 inside.
6, the variable resistor 26 comprises a brush 26a and a resistor 26b printed on a resistor substrate. The rotation speed switching contact 14 includes a fixed contact terminal 14a (which constitutes one brake contact terminal for the DC motor 4), an empty contact terminal 14b (which also constitutes the other brake contact terminal for the DC motor 4), and a low speed. Rotating contact terminal 14
c, high speed rotation contact terminal 14d, and movable contact 14e
And contacts 18 and 20 for switching forward / reverse rotation.
Are fixed contact terminals 18a and 20a, forward rotation contact terminals 18b and 20b, and reverse rotation contact terminals 18c and 20 respectively.
c, and movable contacts 18d and 20d that interlock with each other.

Explaining the circuit operation in the unit 6, first, the brake contact terminals 14a and 14b are short-circuited by the movable contact 14e in a state where the rotation speed operating lever (not shown) is not operated. And forward rotation
Operate the reverse rotation operation lever to switch forward / reverse rotation contact 1
The movable contacts 18d and 20d of 8 and 20 are switched to the forward rotation contact terminals 18b and 20b, respectively. After that, the rotation speed control lever of the electric drill is pulled in and operated. When the pull-in operation amount exceeds the stroke for the pull-in play, the power switch 8 is closed, and the brush 26a starts sliding on the resistor 26b according to the pull-in operation amount on the operating lever, while the rotation speed is switched. The movable contact 14e of the contact for contact 14 contacts the contact terminal 14c for low speed rotation from the empty contact terminal 14b. As a result, the DC motor 4 is released from the state in which both ends are short-circuited by the brake contact terminals, and the current controlled by the control circuit 10 and the FET 12 is passed through the forward rotation / reverse rotation switching contacts 18 and 20. It is applied and driven to rotate in the forward direction, and the drill blade starts drilling the workpiece. Further, when the rotation speed operating lever is further pulled in, the movable contact 14e of the rotation speed switching contact 14 comes into contact with the high speed rotation contact terminal 14d, and the DC power source 2 is directly applied to the DC motor 4 so that the high speed rotation is achieved. It is driven to rotate and the drill blade is driven at high speed.

In this way, when the drilling of the workpiece is stopped, or when it is completed and the rotation speed control lever is returned to the original initial position, the power switch 8 is opened in response to this and the rotation speed switching contact is also opened. The movable contact 14e of 14 also returns to the vacant contact terminal 14b, whereby the fixed contact terminal 14a and the vacant contact terminal 14b are short-circuited at the movable contact 14e, and both terminals 14a, 14b serve as a brake contact for the DC motor 4. The DC motor 4 is braked and rapidly stops. As a result, it is possible to prevent the workpiece from being unnecessarily perforated by the inertial force of the DC motor 4.

As described above, in the trigger switch of this embodiment, the unit is not divided into the rotation speed control unit and the forward / reverse rotation unit as in the conventional case, but these are integrated into the unit 6. No external wiring is required when the configuration is different. Also, the brake contacts 14a, 1
As for 4b, as described later, they are movable contacts 1
The connection is ensured by 4e.

2 to 6 are provided for explaining the mechanical structure of the trigger switch of the present invention and the operation thereof.

First, the structure of the trigger switch will be described with reference to FIGS. 2 to 4. Reference numeral 28 denotes a switch case, and the inside of the switch case 28 is partitioned by a partition wall 30, and a lower partition chamber 32 and an upper part are provided. It is divided into a partition room 34. The through hole 3 is formed in the front chamber wall of the lower partition chamber 32.
6 is provided. The rotation speed control lever 38 has a shape like a trigger of a gun so that the front finger grip 38a can be easily operated by fingers when driving and controlling the rotation of the drill blade of the electric drill. An operation shaft 40 is integrally provided at the rear of 38a. The operation shaft 40 is connected to the lower partition chamber 32 through the through hole 36 of the switch case 28.
While being inserted into the inside, it receives a biasing force in the non-operating direction A from a return spring 42 between the shaft end and the rear chamber wall of the lower partition chamber 32. Further, the operation shaft 40 has a slider housing portion 44 on the upper surface, and the slider housing portion 44 houses the slider 48 together with the contact pressure spring 46. In the lower partition chamber 32, a movable contact 14e is provided on the slider 48 so as to be pressed by the slider 48. The movable contact 14e has a V-shaped receiver 50,
When the protrusion 48a of the slider 48 enters into the receiver 50, the movable contact 14e is moved according to the movement of the slider 48.
Can be moved.

The upper partition chamber 34 accommodates the number of revolutions of the DC motor 4 and a contact member 52 for switching between normal rotation and reverse rotation. The contact member 52 includes the rotation speed switching contact 14 and the forward / reverse rotation switching contact 18 shown in FIG.
Reference numerals are assigned to the respective 20 contact terminals. That is, the contact members 18b-20c correspond to the forward rotation contact terminal 18b and the reverse rotation contact terminal 20c of the forward / reverse rotation switching contacts 18 and 20, and the contact members 18c-20b are also the forward rotation / reverse rotation switching terminals. It corresponds to the reverse rotation contact terminal 18c and the forward rotation contact terminal 20b of the contacts 18 and 20, and the contact member 18a is the fixed contact terminal 1 of the forward rotation / reverse rotation switching contact 18.
8a, the contact member 20a corresponds to the fixed contact terminal 20a of the normal / reverse rotation switching contact 20, and the contact member 18d is normal / reverse.
The contact member 20 is attached to the movable contact 18d of the reverse rotation switching contact 18.
d is the movable contact 20d of the forward / reverse rotation switching contact 20, the contact member 14c is the low speed rotation contact terminal 14c of the rotation speed switching contact 14, and the contact member 14d is the high speed rotation contact terminal 14d thereof. Applicable Contact member 18b
-20c includes an empty contact terminal 14 of the rotation speed switching contact 14.
b, that is, the brake contact terminal 14b is integrally bent, and the fixed contact terminal 14a of the rotation speed switching contact 14, that is, the brake contact terminal 14a is integrally bent, on the contact members 18c-20b. .. (Note that in the following description, not the contact member but the name corresponding to FIG. 1 is used for ease of understanding.) The brake contact terminal 14b is connected to the lower partition chamber 32 through an opening formed in the partition wall 30. The movable contact 14e in the lower partition chamber 32 is brought into contact with the movable contact 14e (shown in a contact state in FIG. 3). The brake contact terminal 14a is the same as the partition wall 3
Is exposed to the lower partition chamber 32 through an opening formed in 0,
The movable contact 14e in the lower partition chamber 32 is always in contact.

The movable contacts 18d and 20d of the forward and reverse switching contacts 18 and 20, respectively, have a U-shaped inside with the contact spring 5.
4, 56 are deployed respectively. The circular rotary member 58 is provided with flanges 58b and 58c at the upper and lower ends of the column 58a, and the contact pressure springs 54 and 56 are provided between the flanges 58b and 58c.
Along with the forward / reverse rotation switching contacts 18 and 20, the movable contact 18
d and 20d are inserted and the upper collar 58b
A protrusion 58d is formed on the bottom.

The forward / reverse rotation operating lever 60 for switching the forward / reverse rotation of the DC motor 4 has a rotation center hole 60a, and the center hole 60a projects from the upper portion of the switch case 28. 62 is inserted.
This forward / reverse rotation operation lever 60 has a projection 58d of a rotating member 58 inserted into a hole formed at the end thereof, and the front portion is rotated in the C and D directions of FIG. Hole 60
The end portion swings with a as a rotation fulcrum, and the rotating member 58 is rotated in response to the swing.

Next, the operation is divided into (a) control of the number of revolutions of the DC motor 4 and (b) control of forward / reverse rotation of the DC motor 4, which will be described with reference to FIGS. 5 and 6, respectively. To do.

(A) Controlling the rotation speed of the DC motor 4 (see FIG. 1)
5 to FIG. 6): First, in the initial state where the rotation speed control lever 38 is not retracted as shown in FIG. The slider 48 housed in 44 presses the movable contact 14 e of the rotation speed switching contact 14 by the urging force of the contact pressure spring 46. Therefore, the movable contact 14e
Is in a state where the brake contact terminals 14a and 14b are short-circuited. In this case, both brake contact terminals 14a,
The movable contact 14e of 14b is surely short-circuited by the pressing of the slider 48 by the action of the contact pressure spring 46. In this state, in the forward / reverse rotation switching contacts 18 and 20, the fixed contact terminals 18a and 20a are in contact with the forward rotation contact terminals 18b and 20b, respectively.
When the rotation speed control lever 38 is pulled in and operated,
As a result of the slider 48 moving in the retracting operation direction together with the operation shaft 40, the movable contact 14e is also moved as shown in FIG. 5B, the movable contact 14e performs a seesaw operation, and the brake contact terminals 14a and 14b are connected. The short circuit is released, and the brake contact terminal 14a and the low speed rotation contact terminal 14c are short-circuited. As a result, the DC motor 4 is supplied with a current for low speed rotation. Further, when the rotation speed operation lever 38 is pulled in and the slider 48 moves together with the operation shaft 40, the movable contact 14e moves so as to short-circuit the brake contact terminal 14a and the high-speed rotation contact terminal 14d, whereby the DC The power supply voltage is applied to the motor 4.

In this way, in this embodiment, the direct-current motor 4 can be rotated at a low speed or a high speed on the forward rotation side by pulling in the rotation speed operation lever 38. The same applies to rotating the DC motor 4 in the reverse rotation direction at a low speed or a high speed, and the description thereof will be omitted.

(B) Control of forward / reverse rotation of the DC motor 4 (explained mainly in FIG. 6 among FIGS. 1 to 6): When the forward / reverse operation lever 60 is in the neutral position in FIG. , The rotating member 5 attached to the rear end of the forward / reverse operating lever 60
8 is in the state of FIG. In this state, the movable contact 18 of each of the forward / reverse rotation switching contacts 18 and 20 is
Neither d nor 20d is in contact with any of the contact terminals for forward rotation and reverse rotation. Then, when the forward / reverse rotation operation lever 60 is rotated in the C direction to rotate the DC motor 4 in the forward direction, the rotating member 58 is rotated in this operation direction, and as a result, movable as shown in FIG. 6B. The contacts 18d and 20d rotate, and the contact terminal 18a and the contact terminals 18b to 20c come into contact with each other by the movable contact 18d, and the contact terminal 20a and the contact terminals 18c to 20b come into contact with each other by the movable contact 20d. .. In this contact state, the contacts of the forward rotation / reverse rotation switching contacts 18 and 20 are switched to the forward rotation side. When the forward / reverse rotation operation lever 60 is rotated in the D direction to rotate the DC motor 4 in the reverse direction, the rotating member 58 is rotated in this operation direction. As a result, as shown in FIG. 18d and 20d rotate, and the contact terminal 18a and the contact terminal 18c are moved by the movable contact 18d.
The movable contact 20d and the contact terminal 20a.
The contact terminals 18b to 20c are in contact with each other. This contact state is the contact 1 for forward / reverse rotation switching.
This means that the contacts 8 and 20 have been switched to the reverse rotation side.

[0036]

As is clear from the above description,
According to claim 1 of the present invention, a slider is provided on the operation shaft of the rotation speed operation lever so as to be movable integrally with the operation lever, and the slider is biased upward and pressed against the slider. A movable contact is provided so as to be movable integrally with the slider, and an empty contact terminal, a fixed contact terminal, and a low speed rotation terminal of the rotation speed switching contact are located above the movable contact and sequentially in the retracting operation direction of the rotation speed operation lever. A contact terminal and a contact terminal for high-speed rotation are provided. When the rotation speed operation lever is not operated, the empty contact terminal and the fixed contact terminal are short-circuited by the movable contact, and in the short-circuited state, these are parallel to the DC motor. Since it is connected to serve as the brake contact terminal of the DC motor, the brake contact terminal can be reliably short-circuited and closed at the movable contact. further,
When the rotation speed operation lever is retracted, the movable contact moves along with the movement of the slider, and the movable contact performs a seesaw operation at the fixed contact terminal at the predetermined moving position. It is possible to secure an insulation distance from the contact terminal for low speed rotation, and at the same time easily secure a stroke for play in operating the rotation speed control lever until the fixed contact terminal and the contact terminal for low speed rotation contact with the movable contact. You can

According to a second aspect of the present invention, the first contact terminal member includes the empty contact terminal, the forward rotation contact terminal of one forward rotation / reverse rotation switching contact, and the other forward rotation / reverse rotation switching. The second contact terminal member also serves as the reverse contact terminal of the contact for use, and the second contact terminal member serves as the fixed contact terminal, the reverse contact terminal of the forward / reverse rotation switching contact on one side and the normal / reverse rotation switching contact on the other side. Since it also serves as the contact terminal for forward rotation, the rotation speed switching contact and the forward rotation / reverse rotation switching contact can be provided not in separate units but in one unit, which is different from the conventional one. The switching contacts are provided in the unit of
The external wiring that connects each unit becomes unnecessary.

[Brief description of drawings]

FIG. 1 is an electrical circuit diagram of a trigger switch according to an embodiment of the present invention.

FIG. 2 is a partially cutaway plan view of a trigger switch.

FIG. 3 is a partially cutaway side view of a trigger switch.

FIG. 4 is an exploded perspective view of essential parts of a trigger switch.

FIG. 5 is a partial side view for explaining the rotation speed control of the DC motor.

FIG. 6 is a partial plan view for explaining forward / reverse rotation control of a DC motor.

FIG. 7 is an electrical circuit diagram of a conventional trigger switch.

FIG. 8 is a side view of a main part of a trigger switch.

[Explanation of symbols] 2 DC power supply 4 DC motor 6 rotation speed / forward / reverse rotation unit 14 rotation speed switching contact 14a fixed contact terminal 14b empty contact terminal (brake contact terminal) 14c low speed rotation contact terminal (brake contact terminal) 14d High-speed rotation contact terminal 14e Movable contact 18,20 Forward / reverse rotation switching contact 18a, 20a Fixed contact terminal 18b, 20b Forward rotation contact terminal 18c, 20c Reverse rotation contact terminal 18d, 20d Movable contact 38 Rotation speed operating lever 40 Operation shaft 42 Return spring 46 Contact pressure spring 48 Slider 58 Rotating member 60 Forward / reverse operating lever

Claims (2)

[Claims] 1. An operating shaft (4) of a rotation speed operating lever (38).
0) is provided with a slider (48) so as to be movable integrally with the operation lever (38), and the slider (48) is biased upward and the slider (4)
A movable contact (14e) is provided so as to be movable integrally with the slider (48) in a state of being pressed against the movable contact (8), and is positioned above the movable contact (14e) to operate the rotation speed operation lever (38).
Rotational speed switching contacts (14) sequentially in the pull-in operation direction
Empty contact terminal (14b) and fixed contact terminal (14a)
, A contact terminal (14c) for low speed rotation and a contact terminal (14d) for high speed rotation are provided, and the fixed contact terminal (14a) is provided so as to project downward from the other contact terminals. When the number operation lever (38) is not operated, the empty contact terminal (14b) and the fixed contact terminal (14a) are short-circuited by the movable contact (14e), and in the short-circuited state, they are parallel to the DC motor (4). Connected to the DC motor (4) to serve as a brake contact terminal, and when the rotation speed operation lever (38) is retracted, the movable contact (14e) moves along with the movement of the slider (48), and the movable contact (14e) moves. The contact (14e) separates from the empty contact terminal (14b) by performing a seesaw operation at the fixed contact terminal (14a) at a predetermined movement position, and at the same time, the fixed contact terminal (1 a) a low speed contact terminal (1
4c) is contact short-circuited, and further, the movable contact (14e) is brought into contact short-circuit between the fixed contact terminal (14a) and the high speed rotation contact terminal (14d) by the movement of the movable contact (14e) associated with the pulling operation. Trigger switch characterized by that. 2. A first contact terminal member (18b-20c)
Therefore, with the empty contact terminal (14b),
Forward rotation contact terminal (18b) of the reverse rotation switching contact (18)
And the reverse contact terminal (20c) of the other forward / reverse rotation switching contact (20), and is integrated with the fixed contact terminal (14a) by the second contact terminal member (18c-20b). To form a reverse rotation contact terminal (18c) of one of the forward rotation / reverse rotation switching contacts (18) and a normal rotation contact terminal (20b) of the other forward rotation / reverse rotation switching contact (20), and , The third and the fourth contact terminal members (18a, 20a), the fixed contact terminal (18a) of one forward rotation / reverse rotation switching contact (18) and the other forward rotation / reverse rotation switching contact (18), respectively. 20) and the fixed contact terminals (20a) of the first and second contact terminal members (18b-20c, 18).
c-20b) are arranged to face each other, while the third and fourth contact terminal members (18a, 20a) are arranged to face each other with the first and second contact terminal members (18b-20c, 18c-20b) interposed therebetween. The trigger switch according to claim 1, wherein the contact terminal members are short-circuited by operating the forward / reverse operating lever (60).