JP2000326264A - Electric rotary tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain decreasing of a loss and improvement of durability, by lessening a lead wire for internal wiring. SOLUTION: This tool is provided with a motor 2 as power, switch part 3 controlling carrying of a current in the motor in accordance with operation of a trigger lever 7, and a switching element 50 connected in series between the motor 2 and a power source to control a rotational speed of the motor 2. The switching element 50 is mounted in a circuit board 51 which is a radiating plate formed with a circuit pattern, the circuit board 51 is fixedly connected to a body of equipment of the switch part 3, and connected to a terminal provided in the switch part 3. The switching element 50 is mounted in the circuit board 51, and it is integrally formed in the switch part 3, so as to eliminate necessity for a lead wire for connection of the switching element 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric rotary tool such as an electric drill and an electric screwdriver, and more particularly to an electric rotary tool having a function of controlling the rotation speed of a motor.

[0002]

2. Description of the Related Art In an electric rotary tool having a motor rotation speed control function, generally, when a trigger lever is pulled, the motor starts rotating, and the rotation speed of the motor is increased as the pull amount of the trigger lever is increased. ing. In this case, the motor is driven via a switching element. Conventionally, a switch block having a trigger lever and a switching element have been arranged as follows.

[0003] That is, the electric rotary tool shown in FIG. 9 includes an impact mechanism section 20 and uses a detachable battery pack 15 as a power source, and is further behind the motor 2 located behind the impact mechanism section 20. And a switching element 50 is mounted on the heat radiating plate 5.

A switch block 3 on which a trigger lever 7 and a rotation direction switching lever 8 are mounted is disposed on the base side of the grip portion of the housing 1. The switch block 3 and the switching element 50 are connected to a lead wire 5.
8, the switch block 3 and the motor 2 are connected to the lead wire 28.
Connected with. In the figure, reference numeral 19 denotes a terminal for connection to the battery pack 15.

[0005]

In this case, a battery power supply is connected from the switch block 3 to the switching element 50 via a lead wire 58, and the switching element 50 is connected to the lead wire 58 and a rotation direction switching contact in the switch block 3. However, the presence of the lead wire 58 causes a loss, and damage or disconnection due to vibration or the like easily causes a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the number of lead wires for internal wiring so as to reduce loss and improve durability. Provide rotary tools.

[0007]

According to the present invention, there is provided a motor as a power, a switch for controlling energization of the motor in response to an operation of a trigger lever, and a series connection between the motor and a power supply. A switching element for controlling the rotation speed of the motor, wherein the switching element is mounted on a circuit board which is a heat sink on which a circuit pattern is formed, and the circuit board is a housing of the switch unit. And is connected to a terminal of the switch unit. By mounting the switching element on the circuit board and integrating the circuit board into the switch section, the lead wire for connecting the switching element is unnecessary.

If the switching element starts and stops the motor in response to the state of a start switch which is turned on and off in response to operation of a trigger lever in the switch section, the switch section has a large size for turning the motor on and off. Since there is no need to provide a mechanical switch having a capacity, the overall size can be reduced.

At this time, if the terminals for connection to the power supply are provided on the circuit board, the electrical connection can be simplified.

The housing of the switch section is composed of a switch case and a switch cover fixed to the switch case, and a mounting groove for inserting a part of a circuit board is provided in the switch case. By providing an engagement portion that engages with the circuit board in a direction perpendicular to the direction of insertion of the circuit board into the mounting groove, the connection and integration of the circuit board can be performed simultaneously with the assembly of the switch section.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an example of an embodiment. The electric rotary tool shown in FIG. 1 also includes an impact mechanism section 20.
, And the switch block 3 is arranged at the base of the grip portion of the housing 1 as in the above-described conventional example. However, the switching element 50 here is housed in the grip portion in a state of being mounted on the circuit board 51 combined with the switch block 3 and also serving as a heat sink.

FIGS. 2 to 5 show the switch block 3 and the circuit board 51. FIG. The switch block 3 has an outer shell formed by a switch case 30 and a switch cover 31 that closes an opening on the lower surface of the switch case 30. The switch case 30 has a rotation direction switching lever 8 attached thereto. A rotation direction switching contact portion SW (see FIG. 8) for switching a contact according to operation of a rotation direction switching lever is provided, and motor connection terminal plates 40, 40 are protruded from an upper surface of the switch case 30, and a lower surface. Circuit board 5 on the side
Terminals 41, 41 for connection with the first terminal 1 are projected.

The switch cover 31 has the trigger lever 7 and the variable resistance board 6 mounted thereon, and has a trigger guide 37 at a front end side for slidably holding a shaft portion 70 of the trigger lever 7.

The variable resistance substrate 6 includes a trigger lever 7
And a variable resistor 62 that changes the resistance value according to the amount of pulling of the trigger lever 7. The connection terminal protrudes from the lower surface of the switch cover 31. Let me.

The circuit board 51 is formed by forming a pattern on a substrate having excellent heat dissipation characteristics, such as aluminum, and also serves as a heat dissipation plate, and has two switching elements 50 mounted on one surface thereof. .

The circuit board 51 is provided with an engagement portion 37 of the switch cover 31 at a notch 56 provided on a side edge thereof.
Is engaged with the mounting groove 3 of the switch case 30.
4 is attached to the switch box 3 by fitting the upper part thereof. At this time, the hooks 32 provided on the switch case 30 engage with the trigger guide 37 on the front end side of the switch cover 31 as shown in FIG. The switch case 30 is fixed by engaging with the engagement hole 33. Circuit board 5
In No. 1, since the switch cover 31 is engaged with the cut 56, the connection between the switch case 30 and the switch cover 31 secures the stopper. The connection between the switch case 30 and the switch cover 31 may be performed by, for example, heat sealing.

The terminals 41, 41 of the switch case 31 are connected to the pattern of the circuit board 51 by soldering or the like, so that the switching elements 50, 50 and the rotation direction switching contact SW are electrically connected. The connection between the switching element 50 and the battery pack 15 is made clear by the terminal 55 of the circuit board 51 and the terminal 19 as shown in FIG.
By connecting with a lead wire 17 to a terminal block provided with. And the circuit board 51 and the variable resistance board 6
The signal line 6 is connected to a control circuit board 66 on which the control circuit 65 is mounted.
6, 67. Further, the motor connection terminal plate 40 and the motor 2 are connected by the lead wire 28.

Here, the switching elements 50, 50
In addition to controlling the rotation speed of the motor 2 in accordance with the amount of pulling of the trigger lever 7 together with the control circuit 65, the motor 2 is also started and stopped. That is,
A start switch 61 that is turned on by operation of the trigger lever 7 is provided in the switch block 3, and the control circuit 65 activates the switching element 50 to energize the motor 2 in response to the start switch 61 being turned on. I have. It is for this reason that the switch block 3 is smaller than the prior art in which the on / off contact portion is disposed in the switch block 3. Although two switching elements 50 are provided in the illustrated example, one is used for on / off and speed control, and the other is used for braking.

If the control circuit 65 can be miniaturized by using an IC or the like, it is preferable that the control circuit 65 is also mounted on the circuit board 51. Control circuit board 6 behind motor 2
6 is not required, and the signal line 66 connecting the circuit board 51 and the control circuit board 66 is not required.

The heat generated by the switching element 50 is radiated from the circuit board 51 which also functions as a heat radiating plate. When the circuit board 51 is also used as a heat sink, the width and thickness of the pattern can be reduced as compared with the case where the circuit board 51 is made of a non-metallic material. be able to.

[0021]

As described above, according to the present invention, the motor as the power, the switch for controlling the energization of the motor in response to the operation of the trigger lever, and the motor connected in series between the motor and the power supply. The switching element is mounted on a circuit board which is a radiator plate on which a circuit pattern is formed, and the circuit board is fixedly connected to a housing of the switch unit. And the connection to the terminals of the switch section, the use of a lead wire for connecting the switching element is unnecessary, and the loss and reduction in durability due to the presence of the lead wire are eliminated. Since the circuit board also serves as a heat sink, the circuit board with the switching elements can be integrated into the switch section. That although, no problem occurs in terms of heat dissipation.

The switching element is configured to start and stop the motor in response to the state of a start switch that is turned on and off in response to operation of a trigger lever in the switch section. Since it is not necessary to provide a large-capacity mechanical switch, the size of the switch unit can be reduced, and accordingly, the overall size can be reduced.

At this time, if the terminals for connection to the power supply are provided on the circuit board, the electrical connection relationship can be simplified.

Further, the housing of the switch section is composed of a switch case and a switch cover fixed to the switch case, and a mounting groove for inserting a part of a circuit board is provided in the switch case. The circuit board can be easily fixed by providing an engagement portion that engages with the circuit board in a direction orthogonal to the direction of insertion of the circuit board into the mounting groove.

[Brief description of the drawings]

FIG. 1 is a sectional view of an example of an embodiment of the present invention.

FIG. 2 is a perspective view of the same switch block.

FIG. 3 is a perspective view of the switch block according to the first embodiment;

FIG. 4 is an exploded perspective view of the switch block.

FIG. 5 is an exploded perspective view of the switch block.

FIGS. 6A and 6B are partial cross-sectional views of the same.

FIG. 7 is a side view of the same.

FIG. 8 is a block circuit diagram of the same.

FIG. 9 is a sectional view of a conventional example.

[Explanation of symbols]

 2 Motor 3 Switch block 7 Trigger lever 50 Switching element 51 Circuit board

Claims (4)

[Claims] 1. A motor as power, a switch unit for controlling energization of the motor in response to operation of a trigger lever, and a switching element connected in series between the motor and a power supply for controlling the rotation speed of the motor. Wherein the switching element is mounted on a circuit board which is a radiator plate on which a circuit pattern is formed, and the circuit board is connected and fixed to a housing of the switch unit and a switch is provided. An electric rotating tool, wherein the electric rotating tool is joined to a terminal provided in the portion. 2. The electric motor according to claim 1, wherein the switching element starts and stops the motor in response to a state of a start switch that is turned on and off in response to an operation of a trigger lever in the switch section. Rotating tool. 3. The electric rotary tool according to claim 2, wherein a terminal for connection to a power source is provided on the circuit board. 4. The switch unit has a housing including a switch case and a switch cover fixed to the switch case. The switch case has a mounting groove into which a part of the circuit board is inserted. The electric rotary tool according to any one of claims 1 to 3, further comprising an engaging portion that engages with the circuit board in a direction orthogonal to a direction of insertion into the mounting groove.