JPH02145118A - Self-propelled mowing machine - Google Patents

Abstract

PURPOSE:To stabilize the speed of a mowing machine and improve the working efficiency by providing a current detector for detecting the current supplied to a DC motor, controlling the output voltage of a regulator nearly proportional to the current detected by the current detector and supplying the voltage controlled electric power from a generator to the DC motor. CONSTITUTION:The objective self-propelled mowing machine is provided with wheels 6 driven by a DC motor 9 and with a regulator 21 to control the voltage of electric power of a generator 15 and supplying the power to the DC motor 9. The current supplied to the DC motor 9 is detected by a current detector 20 and the output voltage of the regulator 21 is controlled nearly proportional to the current detected by the current detector 20. The rotational speed of the motor 9 can be maintained at an almost constant level and the machine speed can be stabilized even on a hillside farm.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a self-propelled brush cutter.

<Prior Art> A conventional self-propelled brush cutter equipped with wheels rotationally driven by a DC motor has a regulator that adjusts the voltage of the output of a generator driven by an engine and supplies it to the DC motor. There is a device in which a DC motor is driven to rotate at a predetermined speed.

<Problem to be solved by the invention> However, in the conventional case, for example, when driving uphill on a slope, a large load is applied to the wheels, which reduces the number of rotations of the wheels, resulting in unstable vehicle speed. There was a problem that work efficiency decreased.

In view of the above-mentioned problems, the present invention aims to improve work efficiency by enabling a brush cutter to run at a stable speed even on slopes or the like.

Means for Solving the Problem> The technical means of the present invention for solving this technical problem is
A generator 1 is provided with wheels 6 that are rotationally driven by a motor 9.
The voltage of the output of D 5 is adjusted by the regulator 21 to
In a self-propelled brush cutter configured to supply current to the DC motor 9, a current detector 2 detects the current supplied to the DC motor 9.
0 is provided, and the regulated voltage of the regulator 21 is controlled to increase or decrease substantially in proportion to the current detected by the current detector 20.

<Function> When climbing up a slope, etc., when a load is applied to the wheels 6 and the rotation speed of the DC motor 9 decreases, the current detector 20 detects that the rotation speed of the motor 9 has decreased by increasing the current of the DC motor 9. Then, the regulated voltage of the regulator 21 is increased approximately in proportion to the detected current, thereby automatically increasing the rotation speed of the DC motor 9. Furthermore, when descending down a slope, etc., when the load on the wheels 6 decreases and the rotation speed of the DC motor 9 increases, the current detector 20 detects that the rotation speed of the motor 9 has increased.
Detected by the decrease in current to the motor 9, the regulator 21
The regulated voltage decreases approximately in proportion to the decrease in the detected current, thereby automatically lowering the rotation speed of the DC motor 9.

<Example> Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a brush cutter main body, which has a control handle 4 formed by connecting a straight rod 2 and a forked rod 3, and the handle 4 extends rearward with an upward slope. The rod 3 also has a grip 5.

Reference numeral ``6'' denotes a single-shaft, two-wheeled wheel that is rotationally driven on a horizontal axis, and is provided on the lower side of the brush cutter main body 1.

Reference numeral 7 denotes a cutting blade body, which is provided on the front side of the brush cutter main body 1 so as to be rotatable around a vertical axis 6, and is rotationally driven by an engine 8. The engine 8 is arranged above the brush cutter main body 1. ing.

9 is a forward/reverse DC motor, which is located on the front side of the brush cutter body 1.
The motor 9, which is attached to the side, is supplied with power from a generator provided in the engine 8, and drives the wheels 6 in forward and reverse directions.

A connecting cylinder 11 connects the engine 8 and the transmission case 12 for the cutting blade body 7.

FIG. 2 shows a motor drive circuit for driving the DC motor 9. In the figure, 15 is a generator, which includes a flywheel magnet (not shown) that is rotationally driven by the engine 8 and a power generation coil 16. The generator coil 16 outputs an alternating current voltage v1 that increases in proportion to engine rotation, as shown by the dotted line in FIG. A full-wave rectifier 17 performs full-wave rectification on the power generation coil 16. 18.1
Reference numeral 9 denotes a sirisk for controlling the phase of the output of the full-wave rectifier 17.

A current detector 20 detects the current supplied to the DC motor 9, and is composed of a resistor connected in series with the motor 9. 21 is a regulator that adjusts the voltage of the output of the generator 15 and supplies it to the DC motor 9; it outputs a detection signal S1 indicating the supplied current detected by the current detector 20 to the current detector 20
The trigger signal S is input to the thyristors 18 and 19.
S, and controls the adjustment voltage applied to the DC motor 9 so that it increases or decreases approximately in proportion to the current detected by the current detector 20. That is, as the current detected by the current detector 20 increases, the regulator 21 increases the si risk 18 in proportion to this.
．． Trigger signals S, , S so that the off period of 19 becomes longer.
, is output at a small phase angle, thereby controlling the regulating voltage of the regulator 21 applied to the motor 9 to be low, and as the detected current of the current detector 20 becomes small, the si risk 18.19 decreases in proportion to this. The trigger signals S, , S, are outputted at a large phase angle so that the off period becomes long, and thereby the regulated voltage of the regulator 21 applied to the motor 9 is controlled to become high. That is, in the DC motor 9, the torque, current, and rotational speed have a proportional relationship as shown in FIG. Therefore, as shown in FIG. 5, if the wheel 6 is loaded and the rotational speed drops, this is automatically detected and the voltage (adjusted voltage of the regulator 21) is increased to control the motor 9.
Increase the rotation speed. Conversely, if the load on the wheels 6 decreases and the rotational speed increases, this is automatically detected and the voltage (adjusted voltage of the regulator 21) is lowered to lower the rotational speed of the motor 9.

FIG. 6 shows a motor drive circuit for driving the DC motor 9, which is different from the present invention, in which 22 is a transistor for phase control, 23 is a variable resistor for motor speed setting, and 24 is a motor drive circuit for driving the DC motor 9. A current detection resistor 25 is an amplifier for detecting the current flowing through the current detection resistor 24, which inputs the current detection signal of the current detection resistor 24 via a filter 26 and amplifies it. A comparison section 27 compares the speed setting signal S from the variable resistor 23 and the current detection signal S2 from the amplifier 25, and outputs a control signal S3 indicating the sum of the two. 2
8 is a PWM converter which outputs a pulse signal for driving the motor corresponding to the speed indicated by the control signal S input from the comparator 27 via the amplifier 29.

That is, as shown in FIG. 7, when the torque of the motor 9 increases and the rotational speed of the motor 9 decreases, the current of the motor 9 increases. Therefore, this current is detected by the current detection resistor 24, and a signal obtained by adding the current value detected by the current detection resistor 24 to the set value set by the variable resistor 23 is outputted to P by the comparison section 27.
By inputting to WM converter 2, PWM converter 2
The duty ratio of the pulse signal No. 8 is increased, the voltage applied to the motor 9 is increased, and the rotation speed of the motor 9 is increased. Further, as shown in FIG. 7, when the torque of the motor 9 decreases and the rotational speed of the motor 9 increases, the current of the motor 9 decreases. Therefore, this current is detected by the current detection resistor 24, and a signal obtained by adding the current value detected by the current detection resistor 24 to the setting value set by the variable resistor 23 by the comparison section 27 is inputted to the PWM converter 28. Accordingly, PW
The duty ratio of the pulse signal of the M converter 28 is made small, and the rotational speed of the motor 9 is reduced.

A variable resistor 33 is used to variably set the maximum current value that can be passed through the motor 9. 34
is a comparator that compares the current detection signal of the current detection resistor 24 with the setting signal indicating the maximum current value set by the variable resistor 33, and when the detected current exceeds the set maximum current value,
A stop signal S4 is output to the PWM converter 28. When the PWM converter 28 receives the stop signal S4 from the comparator 34, it stops outputting the pulse signal, and when an overcurrent flows through the motor 9, the PWM converter 28 stops driving the motor 9.

Therefore, according to the drive circuit shown in FIG. 6, even when the speed setting by the variable resistor 23 is set to a low speed, it is possible to secure the maximum number of revolutions under the applied voltage when the torque is high.

Furthermore, when the load becomes lighter and the wheels 6 are about to run out of control, the applied voltage is reduced (maximum deceleration = application stopped) to prevent runaway. Moreover, there is no need to add a special rotation sensor.

<Effects of the Invention> According to the present invention, a current detector 20 is provided to detect the current supplied to the DC motor 9, and the regulated voltage of the regulator 21 is increased or decreased approximately in proportion to the current detected by the current detector 20. Therefore, the rotational speed of the motor 9 can be kept substantially constant regardless of torque fluctuations of the motor 9, and the vehicle speed can be stabilized even on slopes and the like, and work efficiency can be significantly improved. In addition, the -a regulator used to waste more voltage than necessary by shorting the generator coil, but by controlling the regulated voltage to increase or decrease approximately in proportion to the detected current, this loss can be reduced. This increases overall system efficiency.

[Brief explanation of the drawing]

Figures 1 to 5 show an embodiment of the present invention, with Figure 1 being an overall side view, Figure 2 being a motor drive circuit diagram, Figure 3 being a waveform diagram, and Figure 4 being torque and rotation. A graph showing the relationship between the number and current, and FIG. 5 is a block diagram for motor control. Figure 6 is a motor drive circuit diagram for technical disclosure, Figure 7
The figure is a graph. DESCRIPTION OF SYMBOLS 1... Brush cutter body, 6... Wheels, 9... DC motor, 15... Generator, 20... Current detector, 21
···regulator.

Claims (1)

[Claims] (1) Wheels (6) rotationally driven by a DC motor (9)
), and the output of the generator (15) is connected to a regulator (21).
) in a self-propelled brush cutter that adjusts the voltage and supplies it to the DC motor (9), comprising: a current detector (
20), and the regulated voltage of the regulator (21) is controlled to increase or decrease substantially in proportion to the current detected by the current detector (20).