JPS58127587A - Speed controller - Google Patents

Abstract

PURPOSE:To stabilize the output voltage of a speed controller corresponding to the stroke of an operation unit by providing a semifixed resistor in a control circuit. CONSTITUTION:A switch unit 3 has therein switch mechanisms 4, 5 interlocked to an operation unit 15 and a variable resistor 6. A control circuit controls the firing angle of a thyristor 8 in response to the resistance value of a variable resistor 6. A semifixed resistor 13 is provided in the control circuit, thereby stabilizing the characteristic of the output voltage of a speed controller 20 to the stroke of the operation unit and then sealing the components of the control circuit with epoxy resin or the like. In this manner, the output voltage of the speed controler to the stroke of the operation unit can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device that is used in a power tool or the like and has a speed control function.

FIG. 1 shows a conventional speed control device. In the figure, 1 is a power source and 2 is a motor. 3 is a switch device;
Reference numeral 15 denotes an operating section, and the switch device 3 incorporates a switch mechanism 4.5 and a variable resistor 6 that operate in conjunction with the operating section. 7t: in the control circuit section, thyristor 8, diac 9, capacitor 1°, diode 11. Fixed resistance 1
It has 2 built-in. In addition, the control circuit 1, the thyristor 8, the diac 9, the capacitor υ, and the diode 11
, a fixed resistor 12 is sealed in a case (not shown) with evoki resin or the like. k is a speed control device in which the switch device 3 and the control circuit section 7 are connected. As for the speed control device 14, needless to say, since the switch device 3 and the control circuit section 7 are separate parts, restrictions on storage space can be reduced, for example, when the speed control device 14 is stored in the handle of a power tool or the like. See the effect.

However, on the other hand, since the switch device 3 and the control circuit section 7 are separate parts, and the variable resistor 6#'i is built into the switch device 3, the variable resistor 6#'i, which determines the firing angle of the thyristor 80, The variable resistor 6 could not be trimmed in a state where the resistor 6 was a fixed resistor and electronic components such as a capacitor lO were connected.

In FIG. 3, 1 is the operating section stroke, ■ is the output voltage of the speed control device 14, stroke A is the point at which the switch mechanism 4 interlocked with the operating section 15 is turned on, and stroke BFi is the same as the switch mechanism 5. The point at which the button turns ON, the stroke C, is the point at which the operating section is fully pulled out.

Therefore, as is clear from the above, the output voltage V with respect to the stroke L of the conventional speed control device 1 has a large variation with respect to the characteristic g as shown in the characteristic curve shown in FIG.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to make the output voltage of a speed control device constant, and to fully exhibit the functions of a power tool or the like.

In the present invention, trimming can be performed by connecting a semi-fixed resistor to the control circuit section. This is because a semi-fixed resistor is connected in series with V. The control circuit is the 20d speed control device. Therefore, when the switch device 3 and the control circuit section 4 are connected, the variable resistor 6, the fixed resistor, and the semi-fixed resistor B1, which determine the firing angle of the thyristor 8,
With the electronic components such as the capacitor η connected, trim the semi-fixed resistor B, and then easily connect the case (not shown) K1, the thyristor 8, the diac 9, the capacitor υ, the 1 fixed resistor for the diode, and the semi-fixed resistor. The resistor 13 can be sealed with epoxy resin or the like. Therefore, Figure 3
It is possible to stabilize the output voltage V for the stroke J shown in FIG.

According to the present invention, since the semi-fixed resistor is connected to the control circuit section, the output voltage of the speed control device can be stabilized with respect to the stroke of the operating section.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional speed control device, FIG. 2 is a circuit diagram showing an embodiment of the speed control device according to the present invention, and FIG.
The figure is a diagram showing the relationship between stroke and output voltage of a conventional speed control device and a speed control device according to the present invention. 1 is a power supply, 2 is a motor, 3 is a switch device, 4Fi switch mechanism, 5 is a switch mechanism, 6Fi variable resistor, 7F
i control circuit section, 8 is a thyristor, 9 is a diac, phantom is a capacitor, ll is a diode, BiFi fixed resistor, 13
Fi semi-fixed resistance, 14Fi speed control device, b is the operation unit,
Taku, 17, Nagi is the characteristic, υ is the control circuit section, acceleration is the speed control device, 2 is the anode, 22 is the cathode, and the gate is placed. Name of patent applicant Hitachi Koki Co., Ltd. 436 Figure 1 of 3

Claims (1)

[Claims] A switch device and a control circuit section for controlling the speed of a power tool, etc. are separated and constitute a separate component VC. In a speed control device that includes diacs, capacitors, etc., is there a semi-fixed resistor in the control circuit? A speed control device, wherein the semi-fixed resistor is connected in series or in parallel with the variable resistor built in the switch device.