WO2007083447A1

WO2007083447A1 - Speed controller for portable electric cutting tool

Info

Publication number: WO2007083447A1
Application number: PCT/JP2006/323592
Authority: WO
Inventors: Yasuharu Okada
Original assignee: Ryobi Ltd.
Priority date: 2006-01-20
Filing date: 2006-11-27
Publication date: 2007-07-26
Also published as: CN101351955B; JP4939065B2; JP2007195366A; CN101351955A

Abstract

An electric circular saw (A) having a soft start function with which the rotational speed of a motor (9) reaches a preset speed in a constant speed operation region after a predetermined soft start time after the start of the motor. Response of rotational speed feedback control applied to the motor (9) is slowed and overshoot control is performed at a point after the start of the motor (9) at which point the motor operation is changed from an acceleration operation region to a constant speed operation region, where the overshoot control is control for forcibly allowing the speed of the motor (9) to exceed set speed that is most appropriate for cutting and then allowing the speed to decrease to the set speed. Consequently, reaction opposite to that occurring while motor operation is changed from the acceleration operation region to the constant speed operation region is suppressed without extending the soft start time, and as a result, workability and operability of the electric circular saw (A) are enhanced.

Description

Specification

Speed control device for portable electric cutting tool

Technical field

TECHNICAL FIELD [0001] The present invention relates to a speed control device for a portable electric cutting tool, and particularly relates to a device having a soft start function.

Background art

[0002] Portable electric cutting tools such as electric circular saws have a large reaction when the electric motor is started. For this reason, conventionally, in the speed control of an electric motor, a method for suppressing the reaction of the electric motor by performing a control called a soft start function for about 0.7 to 2 seconds from the start is generally known. Yes. This soft-start function suppresses the reaction at the time of start-up (reverse reaction opposite to the rotation direction of the motor), and the acceleration suddenly disappears when moving from the acceleration operation area (soft start area) to the constant speed operation area. It also has a function to suppress the reaction caused by the reverse of the start-up.

[0003] On the other hand, when the soft start is completed and the operation shifts to the constant speed operation region, the overshoot in which the rotation speed transiently exceeds the set speed and becomes a large rotation speed shifts to the acceleration operation region force constant speed operation region. There is a risk that a resonance state will occur in the electric tool that not only lengthens the time required for the transition region during the period and degrades the operability. For this reason, it has been proposed to minimize this overshoot (see Patent Document 1).

[0004] By the way, regarding the soft start, for example, as shown in FIG. 4, when it is assumed that there is no overshoot, in the constant speed operation region, in the speed control in which the rotation speed of the motor is controlled at the set speed vl, When the acceleration operation area is activated with the slope A by the soft start time tl and when the acceleration operation area is activated with the inclination B by the soft start time t2 (> tl) longer than the soft start time tl Compared with the start at the inclination A, the reaction at the start at the inclination B is smaller.

[0005] In addition, at points C and D, which move from the acceleration operation region to the constant speed operation region, the acceleration suddenly becomes 0 with the end of the soft start, and therefore, it receives a reaction opposite to that at the start. . However, if the soft start time until reaching the constant speed operation range is made longer, the opposite is true. There is less movement. That is, the direction force at point D with a long soft start time t2 until reaching the constant speed operation region as shown in slope B. Compared to point C with a short soft start time tl as shown in slope A, it is less susceptible to the reverse reaction.

Patent Document 1: Japanese Patent Publication No. 3-6744

Disclosure of the invention

Problems to be solved by the invention

[0006] By increasing the soft start time until reaching the constant speed operation region in this way, it is possible to suppress the reaction at the time of activation and the reaction opposite to that at the time of activation.

[0007] On the other hand, in the case of an electric cutting tool (for example, an electric circular saw, etc.) that is frequently used by turning the power ON and OFF, on the other hand, if the soft start time until reaching the constant speed operation region becomes long Therefore, the time to reach the constant speed operation range, which is the optimum speed (set speed) for starting cutting, that is, the starting start force, the waiting time until the work can be performed at the optimum speed becomes longer, and the workability is very poor. Problem arises.

[0008] Further, when the occurrence of overshoot is eliminated or reduced as in Patent Document 1, the above-described reverse reaction occurs without being canceled or reduced by the overshoot.

[0009] In particular, in an electric cutting tool having a heavy tool with a large diameter, such as an electric circular saw, at the point C that moves from the acceleration operation region to the constant speed operation region, the tool is moved by the inertia of the tool. The large acceleration that occurs suddenly becomes zero, so that the reaction at the start (the force that tries to lower the front side of the circular saw with the hand holding the handle as a fulcrum) This force is generated to lift the front side of the circular saw with the hand holding the fulcrum as a fulcrum), but this reverse reaction can be suppressed (cancelled) by the above-mentioned or reduced overshoot. It will occur as it is. For this reason, it is inevitable that the operability will deteriorate.

[0010] An object of the present invention occurs when shifting from an acceleration operation region to a constant speed operation region without increasing the soft start time by devising speed control of the electric motor in a portable electric cutting tool. The purpose is to improve the workability and operability of the portable electric cutting tool by suppressing the reverse reaction from the start-up. Means for solving the problem

[0011] In order to achieve the above object, in the present invention, in the control having the soft start function, the acceleration operation region force is deliberately suppressed in order to suppress the reaction reverse to the start-up when moving to the constant speed operation region. The overshoot was forcibly generated.

[0012] Specifically, in the first invention, the portable electric cutting tool having a soft start function for causing the rotational speed of the electric motor to reach the set speed in the constant speed operation region after a predetermined soft start time as the starting force At the end of the soft start function, the motor rotation speed overshoot control is forced so that the rotation speed of the motor once exceeds the set speed in the constant speed operation region and then decreases to the set speed. Provide speed control means to perform automatically.

[0013] According to the above configuration, when the motor is started, the set speed of the constant speed operation region is reached after a predetermined soft start time from the start by the soft start function, and this acceleration operation region (soft start region) The overshoot control is compulsorily performed by the speed control means at the point that shifts to the constant speed operation region. Then, after the rotational speed of the electric motor exceeds the set speed, which is the optimum speed for cutting the cutting tool, control is performed to drop to the set speed. Therefore, the reverse reaction when the soft start region ends and the acceleration disappears can be reduced without increasing the soft start time, and the operability is improved.

[0014] Further, since it is not necessary to lengthen the soft start time, it is possible to quickly start up to the set speed, and the workability is greatly improved.

[0015] In the second invention, the speed control means performs overshoot control by reducing the responsiveness of the rotational speed feedback control (phase control voltage) to the electric motor. Thus, overshoot can be easily generated.

[0016] In the third invention, the portable electric cutting tool is an electric circular saw. Thus, a portable electric cutting tool that can effectively exhibit the above-described effects can be obtained.

The invention's effect

[0017] As described above, according to the first and third inventions, at the point where the acceleration operation area force after the motor starts up and the constant speed operation area, the rotation speed of the motor is set to the optimum setting speed for cutting. Forced overshoot control to drop to the set speed after exceeding once, to reduce the reverse reaction when the soft start area ends without accelerating the soft start time and acceleration force increases Therefore, both the operability and workability of the portable electric cutting tool can be improved.

[0018] According to the second invention, overshoot control can be easily performed by reducing the response of the phase control voltage to the motor and performing the overshoot control.

Brief Description of Drawings

FIG. 1 is a circuit diagram of a speed control device for an electric circular saw according to an embodiment of the present invention.

FIG. 2 is a right side view showing the configuration of the electric circular saw.

[Fig. 3] Fig. 3 is a characteristic diagram showing a characteristic in which the motor rotation speed is changed by overshoot control.

FIG. 4 is a characteristic diagram for explaining the soft start function.

Explanation of symbols

[0020] A Electric circular saw (portable electric cutting tool)

A1 Speed control device

1 Housing

9 Motor (electric motor)

12 Transmission gear mechanism

20 circular saw blade

30 IC

43 Speed sensor

46 Speed control means

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. The following description of preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or its uses.

FIG. 2 shows the configuration of an electric circular saw A as a portable electric cutting tool according to an embodiment of the present invention. Shown schematically. This electric circular saw A has a housing 1. The housing 1 has a bottomed cylindrical motor case 2 that extends in the horizontal left-right direction (a direction orthogonal to the paper surface of FIG. 2) and has an open right end (front side in FIG. 2), and a right end of the motor case 2 A sealed gearbox 3 that is integrally attached and fixed to the motor, and a circular saw blade cover 4 that is integrally assembled to the outer periphery of the right end of the motor case 2 and that is open on the lower side. . Inside the motor case 2, a motor 9 (electric motor) having an output shaft 9a extending horizontally in the horizontal direction is housed and fixed by projecting the output shaft 9a into the gear box 3, and the outer periphery of the output shaft 9a A gear portion 10 is formed on the top. In addition, a handle 5 for operating the electric circular saw A is fixed to the upper part of the motor case 2 physically.

[0023] In the gear box 3, an intermediate shaft 17 and a saw blade shaft 18 extending horizontally and horizontally are supported so as to be rotatable. A first intermediate gear 13 that meshes with the gear portion 10 of the motor output shaft 9a and has a larger diameter than the gear portion 10 is disposed at the left end portion of the intermediate shaft 17, and a first intermediate gear 13 is disposed at the right end portion. A second intermediate gear 14 having a smaller diameter is provided integrally with each other. On the other hand, a third intermediate gear 15 that meshes with the second intermediate gear 14 and has the same diameter as that of the second intermediate gear 14 is provided integrally with the left end portion of the saw blade shaft 18. The right end portion of the saw blade shaft 18 protrudes outside the gear box 3, and the circular saw blade 20 is attached to the projecting portion (right end portion) by a mounting bolt 21 that is screwed to the front end surface thereof. When mounted on the shaft 18, the substantially upper half of the circular saw blade 20 is covered with the circular saw blade cover 4.

[0024] The rotation of the output shaft 9a of the motor 9 is decelerated and transmitted to the circular saw blade 20 by the gear portion 10 and the first to third intermediate gears 13 to 15 of the motor output shaft 9a. A transmission gear mechanism 12 for rotating the saw blade 20 in the counterclockwise direction in FIG. 2 is configured.

Note that a surface plate 7 is disposed on the lower side of the housing 1. The surface plate 7 has a front end portion (right end in the figure) fastened to the front end of the housing 1 via a fastening member 6 so that the rotation angle of the circular saw blade 20 can be adjusted. The amount of protrusion to the bottom of the surface plate 7 (the cutting depth of the electric circular saw A) is adjusted.

[0026] Reference numeral 8 denotes a safety cover that is rotatably supported at the right end of the gear box 3. The safety cover 8 enters the circular saw blade cover 4 of the housing 1 while being rotated by being pushed by the work when cutting a work (not shown). 22 is the above circular saw blade force This is a chip discharge opening opened in the right wall of bar 4.

FIG. 1 shows a circuit diagram of a speed control device A1 for controlling the rotational speed (number of revolutions) of the motor 9 of the electric circular saw A having the above configuration. This speed control device A1 is connected to a commercial power supply 100VAC by turning on an operation switch (not shown) provided on the handle 5 of the electric circular saw A. The speed control device A1 has a soft start function for causing the rotational speed of the motor 9 to reach the set speed in the constant speed operation region after a predetermined soft start time of the starting force. The speed control device A1 has a dedicated IC30 (U-211B), which also has a phase control IC power having a soft start function and a rotation speed feedback function. The motor 9 is composed of, for example, a commutator motor. In FIG. 1, the motor 9 is indicated by its field coil and amateur coil.

[0028] The IC30 includes a power supply voltage control unit 31 that controls a power supply voltage formed by a capacitor C1, a resistor R1, and a diode D1 from 100 VAC, a voltage monitoring unit 32 that monitors the voltage, and a seventh pin of the IC30 Connected to the FZV converter 33 that converts the output pulse signal (frequency) of the rotation speed sensor 43 that detects the rotation speed (rotation speed) of the motor 9 into voltage, and the motor 9 is soft-started at startup. Control amplifier 35 that compares the output of the FZV converter 33 and the set speed of the constant speed operation range set by the resistor R13 connected to the 6th pin of IC30 and the variable resistor VR. A phase control block 36 that performs phase control based on the output of the control amplifier 35, and a pulse output unit 37 that outputs a trigger pulse to the gate terminal of the TRIAC 44 connected to the 4th pin by the output of the phase control block 36. With A voltage detecting unit 38, a current detection unit 39, the load limiting section 40, a reference voltage unit 41 and the like.

[0029] The soft start unit 34 is configured to cause the rotational speed of the motor 9 to reach the set speed in the constant speed operation region after a predetermined soft start time has elapsed since the start-up by turning on the power. The soft start time is determined by the value of the capacitor C3 connected to the 12th pin of the IC30. In this embodiment, the soft start time is set to about 0.7 seconds, for example.

[0030] In addition, by setting the capacitors C7 and C8 and the resistor R7 connected to the 11th pin of the IC30 so as to make the response of the rotational speed feedback control (phase control voltage) to the motor 9 dull, At the end of the soft start function, the rotation speed of the motor 9 Overshoot control is performed to forcibly reduce the set speed once it exceeds the set speed (optimal cutting speed) of the rolling region. In this embodiment, the capacitors C7 and C8 and the resistor R7 constitute speed control means 46 for performing overshoot control.

Therefore, in the above embodiment, when 100 VAC is input to the speed control device A1 by turning on the operation switch of the electric circular saw A, the power is supplied to the IC 30 by the capacitor Cl, the resistor R1, and the diode D1. Is supplied. The trigger pulse is output from the pulse output section 37 of IC30 to the gate terminal of TRIAC44 by the 4th pin, and the motor 9 starts and starts rotating.

[0032] Further, the rotational speed of the motor 9 is detected by the rotational speed sensor 43, and the rotational speed information is input to the FZV conversion 33 by the 7th pin of the IC 30 and converted into a voltage corresponding to the number of pulses.

[0033] Then, a voltage corresponding to the set rotational speed set by the resistor R13 and the variable resistor VR is input to the + pole of the control amplifier 35 via the 10th pin of the IC30. This voltage is compared in the control amplifier 35 with the voltage of the motor speed input to the pole and converted into the voltage, and the output of the control amplifier 35 is connected to the TRIAC 44 through the phase control block 36 and the pulse output unit 37. The angle is changed, and feedback control is performed so that the rotational speed of the motor 9 detected by the sensor 43 becomes the set rotational speed.

[0034] Here, if the response speed of the rotational speed feedback control (phase control voltage) determined by the values of the capacitors C7 and C8 and the resistor R7 connected to the 11th pin of the IC30 is increased (or improved), Or, if the inrush current is eliminated or reduced, as shown by the broken line in Fig. 3, the transition from the acceleration operation area to the constant speed operation area (set speed area)! The overshoot, which is a phenomenon that the rotational speed increases, can be reduced. However, if the overshoot is reduced, the acceleration suddenly becomes 0 or smaller at the point C at the time of transition from the acceleration operation region to the constant speed operation region, and the reaction opposite to that at the start (arrow a in FIG. 2). As shown in Fig. 4, a force to lift the front side of the circular saw A is generated with the hand holding the handle 5 as a fulcrum.

However, in the electric circular saw A according to this embodiment, the capacitors C7 and C8 and the resistor R7 Is set so as to lower (dull) the response of the rotational speed feedback control (phase control voltage). Therefore, as indicated by the solid line in Fig. 3, the motor 9's rotational speed is forcibly increased U (acceleration) during the transition from the acceleration operation region to the constant speed operation region (set speed region), resulting in overshoot. Occurs, exceeds the set speed vl, which is the optimum speed for the cutting operation, and then smoothly shifts to the set speed vl. In this way, since the rotation speed (speed) of the motor 9 at the end of the soft start is overshooted more than the set speed, and smoothly transitions to the set speed, The reverse reaction can be suppressed and the operability of the electric circular saw A can be improved. For example, the broken line in Fig. 3 is C7 = 3.3 / z F, C8 = 0.22 / z F, and the resistance R7 is 22 Ω, whereas the solid line is C7 = 3.3 F, C8 = 0.2 μF, resistor R7 is 33ΚΩ.

[0036] That is, since it becomes possible to suppress a reaction reverse to the startup without taking a long soft start time, for the operator using the electric circular saw A, the rotational speed is low at the startup. It is no longer necessary to increase the waiting time for soft start until the set speed is reached. Therefore, it is possible to improve the operability without impairing the workability of the electric circular saw A.

[0037] (Other Embodiments)

In the above embodiment, the force for performing overshoot control by slowing down the response of the rotational speed feedback control (phase control voltage) to the motor 9 is not limited to the above method. Perform overshoot control by the method described above.

In addition, the above embodiment is an example applied to the electric circular saw A, but the present invention can be applied to portable electric cutting tools other than the electric circular saw A, and the same function and effect. Can be played.

Industrial applicability

[0039] The present invention suppresses the reaction opposite to the start-up that does not increase the waiting time due to the soft start of the portable electric cutting tool more than necessary, and achieves both workability and operability. Therefore, it is extremely useful and has high industrial applicability.

Claims

The scope of the claims

[1] In a speed control device for a portable electric cutting tool equipped with a soft start function that allows the rotational speed of the motor to reach the set speed in the constant speed operation region after a predetermined soft start time,

Speed control that forcibly performs overshoot control of the rotation speed of the motor so that, after the soft start function ends, the rotation speed of the motor exceeds the set speed in the constant speed operation range and then drops to the set speed. A speed control device for a portable electric cutting tool, characterized in that means is provided.

[2] In the speed control device of the portable electric cutting tool according to claim 1,

The speed control device for a portable electric cutting tool, wherein the speed control means performs overshoot control by slowing down the responsiveness of the rotational speed feedback control to the electric motor.

[3] In the speed control device for the portable electric cutting tool according to claim 1 or 2,

A speed control device for a portable electric cutting tool, wherein the portable electric cutting tool is an electric circular saw.