JPS63103623A - Motor-driven machine - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to electric equipment.

[Background technology]

Traditionally, electric machines such as electric drills are often
It is equipped with a safety means that detects an overload on the motor and cuts off the power to the motor.

As this safety means, an overcurrent breaker or the like having a reset button as a reset means is generally used.

Such safety measures rarely operate when the electric equipment is normally used, and do not cause any inconvenience in use.

However, many general consumers, such as so-called do-it-yourselfers who only work on occasional holidays, are unaware of the existence of this safety measure. Even if someone knows the reset button, it is located in a position that is not used often, so when the safety measures are activated due to severe usage, they cannot immediately locate the reset button and think that it is a malfunction. There were times when I misunderstood.

On the other hand, construction workers and other people who frequently use electric equipment on a daily basis may use them in harsh ways, and they believe that if safety measures are used too much each time, it will not be a good job. , the reset button was always fixed in the activated state, which caused a safety problem.

[Purpose of the invention]

In view of these circumstances, the purpose of the present invention is to provide an electric device in which the safety means can be easily released, the safety means cannot be intentionally disabled, and the safety means can operate reliably. [Disclosure of the Invention] In order to achieve the above object, the present invention includes an electric motor that is driven and stopped by operating an open/close switch, and also includes a safety means that detects overload of the electric motor and cuts off the current supply. The gist of the present invention is an electric device including a reset means for the safety means, wherein the reset means operates in an open operation position of the opening/closing switch.

The present invention will be described in detail below with reference to examples thereof.

FIG. 1 and FIG. 2 show one of the electric equipment according to the present invention.
Hail examples. As shown in the figure, this electric equipment is
Inside the body (main body housing) 1, there is an electric motor (motor)
2. Switching element 3 and overcurrent breaker (hereinafter referred to as “
It has a built-in circuit breaker. Electric motor 2
．． The switching element 3 and the breaker 4 are connected to a lead wire 9
are connected in series via... Therefore, when either the switching element 3 or the breaker 4 is opened, the electric motor 2 is not energized. A tip end 21a of the rotating wheel 21 of the electric motor 2 projects outward from a hole 11 formed at one end of the body 1. A collect chuck 22 is provided at the tip 21a. A tool such as a grindstone 23 is replaceably attached to the collect chuck 22. The switching element 3 is closed when the button 31 is pressed, and opened when the button 31 is no longer pressed.

The breaker 4 is a safety means that cuts off power to the electric motor 2 when an overload is applied to the electric motor 2 and an overcurrent flows. This breaker 4 has a reset button 4 as a reset means.
1, and can be reset by pressing this reset button 41. The switching element 3 and the breaker 4 are built into the body 1 so that the respective buttons 31 and reset buttons 41 face each other with a gap between them. On the side wall of body 1,
A long hole 13 is provided through which the switch lever 12 projects outward. The switch lever 12 is configured to move back and forth in the longitudinal direction of the body 1 along this elongated hole 13.

The switch lever 12 includes an operating piece 12a inside the body 1. The operation piece 12a is disposed between the button 31 and the reset button 41, and when the switch lever 12 is moved forward, that is, toward the electric motor 2, the operation piece 12a as shown in FIG.
), when the button 31 is pressed to drive the electric motor 2 and move it backwards, that is, toward the power cord 6 side,
Press the reset button 41 to keep the breaker 4 in the reset state. When the switch lever 12 is moved rearward, the switching element 3 is opened. Therefore, if an overcurrent flows due to an overload while the electric motor 2 is being driven, and the reset button 41 pops out and the power is cut off, as shown in FIG. As you can see, once you move it backwards and set the open/close switch to the open operation position, the reset button 41 that was protruding will be replaced by the operating piece 12.
It is pushed by a and returns to the return position. Therefore, if the load on motor 2 is removed,
Move the switch lever 12 forward again and press the button 31.
If you press , it will operate normally. In addition, in Figures 1 and 2, 7 is the power cord, 8
is a rubber cap.

FIG. 4 shows an internal circuit of another embodiment of the electric equipment according to the present invention. As shown in the figure, this electric device is equipped with a safety circuit (safety means) composed of a comparator Com1 and an electronic switch Q2. The comparator COm 1 has an operational amplifier OP, and also has a self-holding circuit composed of a resistor R6 and a diode D1. A divided voltage ■1 by resistors R9 and R2 is applied to the inverting input terminal (-) side of the operational amplifier OP.
A voltage 2 determined by the resistance values of the resistors R3 and R5 and the electric motor M is applied to the non-inverting input terminal (+) side. When the open/close switch S is closed and the motor M is operating normally, the resistors R,
, R, , R3, and R1 are set so that a negative potential is output from the output terminal. When the output from the operational amplifier OP is in a negative state, the transistor Q is in an open state, so the transistor Q2 acts as an electronic switch.
remains closed and the motor operates normally. Electric motor M
When an overload is applied to and the load current increases, the resistance loss of the resistor R3 increases, so that 2 increases. (2) When 2 increases to V, <V2, the output of the operational amplifier OP is inverted to a positive potential. Therefore, transistor Q is closed, transistor Q2 is opened, and power to motor M is cut off. As mentioned above, comparator Com1
is equipped with a self-holding circuit consisting of a resistor R1 and a diode D1, so the output from the output terminal is fed back to the non-inverting input terminal (+), and the motor M stops. Even if the current value decreases, the transistor Q, once closed, continues to remain closed.

When the open/close switch S is opened, the self-holding of the comparator Com1 is released and the safety circuit returns to the reset state. Therefore, if the load on motor M is removed,
When the open/close switch S is closed again, the electric motor M operates normally. Capacitor C1 installed in parallel with resistor R1s
■2 momentarily changes to Vl at the moment when switch S is closed.
The electric equipment according to the present invention, which is intended to prevent the safety circuit from malfunctioning due to <■, is not limited to the above embodiment. For example, in the embodiment, the electric device is a hand-held type, but it may be a fixed type as long as it is equipped with an electric motor. The safety circuit is also not limited to that of the embodiment.

〔Effect of the invention〕

As described above, in the electric equipment according to the present invention, the safety means is reset at the open operation position of the switch, so the safety means can be easily released, and moreover, the safety means can be prevented from being activated intentionally. Therefore, safety equipment can be operated reliably and work can be carried out safely.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of one embodiment of the electric equipment according to the present invention, Fig. 2 is a perspective view thereof, and Figs. 3(a) to (C).
1 is a partial side sectional view illustrating the states of the switching element and the breaker depending on the operating position of the switch lever, and FIG. 4 is a circuit diagram of another embodiment.

Claims (3)

[Claims] (1) An electric device that includes an electric motor that is driven and stopped by operating an on/off switch, a safety means that detects an overload of the motor and cuts off energization, and a reset means for the safety means, the reset means An electric device characterized in that the switch is adapted to operate in the opening operation position of the opening/closing switch. (2) Claim 1, wherein the safety means comprises a breaker equipped with a reset button, and when the opening/closing switch is opened, the reset button is mechanically reset. Electric equipment listed. (3) The safety means consists of a comparator with a self-holding function built into the drive circuit of the motor and an electronic switch operated by the function of this comparator, and when the motor is overloaded, the load current When the value exceeds a certain value, the comparator operates the electronic switch to cut off the power to the motor and maintain this state by itself, and this self-maintaining state is maintained when the open/close switch is opened. The electric device according to claim 1, which is adapted to be released.