JPH0249138B2 - JIDOSEIMAIKI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a rice milling machine, and more particularly to an automatic rice milling machine that can prevent grain sticking in a milling room and overload of a rice milling motor.

BACKGROUND ART A rice milling machine, for example, a circulating automatic rice milling machine, is provided with a resistor in order to adjust the milling pressure.

This resistor is slidably provided on the wall of the vertical whitening chamber, and as the amount of protrusion into the whitening chamber increases, whitening pressure increases.

Conventionally, the amount of protrusion of this resistor has been automatically adjusted as follows.

The current detection circuit detects the current of the rice milling motor that drives the grain feeding rolls, converts this detected current to voltage via the voltage conversion circuit, and compares this voltage with the reference voltage for setting the rice milling power. At the same time, the position adjustment motor is driven by the output of the comparison circuit via the drive circuit, and the resistor is made to slide, thereby adjusting its position. That is, in this method, the resistor is moved depending on the current value of the rice milling motor, so that the best resistance is applied to the hardness of the grains.

Problems to be Solved by the Invention In conventional rice milling machines, the resistor moves depending on the current level of the rice milling motor.
When the circulation of grains is stopped due to obstructions such as straw waste, the internal pressure in the milling chamber decreases and the load on the rice milling motor decreases.

Naturally, as the current value of the rice polishing motor decreases, the resistor protrudes abnormally, and in the worst case, it protrudes to the maximum extent and stops at the maximum protrusion position due to the action of the limit switch.

Under these conditions, when the grain resumes recirculation, the resistor protrudes too far and an abnormally large milling force is applied to the grain, causing the grain to stick in the milling chamber and making it impossible to mill the rice. There may be cases where this occurs.

Moreover, since an abnormal load is applied to the rice polishing motor, the motor may break down.

In view of the above circumstances, it is an object of the present invention to prevent grain sticking in a milling room and overload of a rice milling motor.

Means for Solving the Problems This invention provides a basic control circuit that outputs an adjustment signal depending on the level of current value of a rice milling motor, a drive circuit connected to the basic control circuit, and a position of a resistor connected to the drive circuit. In a rice milling machine equipped with an adjustment motor, a gate circuit is provided between the basic control circuit and the drive circuit, and the output terminals of the rotation period reading device and the power supply frequency reading device are connected to a pulse period comparison device, and the pulse period is The automatic rice polishing machine is characterized in that the output end of the comparison device is connected to the gate circuit.

Function The basic control circuit operates depending on the current value of the rice milling motor, outputs an adjustment signal, and operates the drive circuit.

When this drive circuit operates, the position adjustment motor rotates forward or reverse, and the amount of protrusion of the resistor is adjusted.

During rice milling, if the circulation of grains stops due to obstructions such as straw waste, the rice milling motor approaches a no-load state and the amount of protrusion of the resistor gradually increases, but at this time, the rotation period can be read. Since the output pulse periods of the device and the power frequency reading device are almost the same, the correction signal of the pulse period comparison device enters the gate circuit, operating the drive circuit independently of the adjustment signal of the basic control circuit, and performing position adjustment. Reverse or stop the motor and adjust the amount of protrusion of the resistor.

Embodiment An embodiment of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, A is a circulating automatic rice milling machine, 1 is a hopper, 2 is a grain feeding roll disposed in a grain feeding roll chamber 3, 4 is a rice milling motor that drives the grain feeding roll 2,
Reference numeral 5 denotes a mounting box provided on the wall 7 of the vertical whitening chamber 6, and this box 5 is provided with a resistor 8 that projects into the vertical whitening chamber 6, as shown in FIGS. 1 and 2. Ori,
This resistor 8 is connected to a position adjustment motor 10 via a coupling 9, and the protrusion amount l of the resistor 8 changes as the motor 10 rotates forward and backward.

This resistor 8 is provided with a stopper 11 so as to prevent the resistor 8 from protruding beyond the maximum amount of protrusion and at the same time to prevent the resistor 8 from rotating.

In FIG. 4, 12 is a power source for the rice milling motor 4, B is a basic control circuit, and this circuit B includes a current detection circuit 13 that detects the current of the rice milling motor 4;
It is composed of a voltage conversion circuit 14 and a comparison circuit 15 that compares the reference voltage of the rice polishing power setting device 16 and the output voltage of the voltage conversion circuit 14. 17 in Figure 3
1 is a rotation period reading device consisting of a magnet 18 and a magnetic sensing element 19, and the magnet 18 and the magnetic sensing element 19 face each other at a constant interval.

The magnet 18 is connected to the motor pulley 2 of the rice polishing motor 4.
0, and the magnetic sensing element 19 is fixed to the main body of the rice polishing motor.

This reading device 17 is configured so that the rice polishing motor 4 is
The magnetic sensing element 19 has the function of catching the magnetic force of the magnet 18 every rotation and generating an output.

That is, N pulses are generated at equal intervals during one revolution of the rice polishing motor 4. In this embodiment, since there is only one magnet 18, the number of pulses is 1 per revolution.
It becomes a pulse.

21 is a power supply frequency reading device, which generates one pulse for every cycle of the power supply frequency.

Therefore, the 50Hz zone will have 50 pulses, and the 60Hz zone will have 60 pulses.

22 is a pulse period comparator, and this device 22
is the output pulse period of the rotation period reading device 17
It has a function of comparing T ₁ and the output pulse period T ₂ of the power supply frequency reading device 21 and outputting a correction signal to the gate circuit 24 when the rotation speed of the rice polishing motor 4 is almost synchronized with the power supply frequency.

When the pressure applied to the grain feeding roll 2 decreases to near zero, the torque applied to the motor 4 also decreases to near zero, and as a result, the motor rotation speed becomes approximately equal to the synchronous rotation speed.

The synchronous rotation speed in an induction motor is expressed by the following formula.

Synchronous rotation speed (RPS)=2/P×f (1) In this equation (1), P is the number of poles of the motor, and f is the power supply frequency (Hz).

Therefore, the period T per rotation of the motor 4 is expressed as follows.

T=P/2f (2) When the right and left sides of equation (1) or equation (2) are approximated, it indicates that almost no load is applied to the motor 4.

When the rotation speed of the rice polishing motor 4 is synchronized with the power supply frequency according to equation (2), T ₁ =P/2Nf (3) In equation (3), N indicates the number of magnets 18.

T ₂ = 1/f...(4) Substituting equation (4) into equation (3), T ₁ = PT ₂ /2N...(5) That is, when the right side and left side of equation (5) are approximate, the pulse The period comparator 22 outputs a correction signal to the gate circuit 24. When the correction signal from the pulse period comparator 22 is output, the gate circuit 24 controls the drive circuit 25 regardless of the state of the output in the comparator circuit 15.
A signal indicating whether to stop or reverse the position adjustment motor 11 is output.

When the rice milling motor 4 is driven and the grain feeding rolls 2 are rotated, grains such as paddy and brown rice in the hopper 1 are forcibly circulated in the direction of the arrow 1A, and polished by the frictional force during the circulation. The polishing pressure is adjusted by the protrusion amount l of the resistor 8, and the adjustment of the protrusion amount l is as follows:
This is done automatically as follows.

That is, when the rice polishing motor 4 is driven, the current value is detected by the current detection circuit 13, and this detected current is converted into a voltage value via the voltage conversion circuit 14.

Then, this voltage and the reference voltage set by the rice polishing power setting device 16 are compared by the comparison circuit 15,
When both voltages are equal, a correction signal is output, and the output signal is input to the gate circuit 24. The adjustment signal output from the gate circuit 24 operates the drive circuit 25 to reverse or stop the position adjustment motor 11, and causes the resistor 8 to slide.
The protrusion amount l is adjusted.

During rice milling, when the circulation of grains is stopped due to a disturbance such as straw waste, the internal pressure in the milling chamber 6 decreases, the load on the rice milling motor 4 decreases, and at the same time, the current value of the rice milling motor 4 decreases. When the load on the rice polishing motor 4 approaches no load, the rotation speed of the motor 4 and the synchronous rotation speed become approximately equal.

At this time, when the output pulse period T ₁ of the rotation period reading device 17 and the output pulse period T ₂ of the power supply frequency reading device 21 satisfy the formula T ₁ ≒ PT ₂ /2N, a correction signal is output from the comparator 22, and this The output signal enters the gate circuit 24, which issues a stop or reverse signal to the drive circuit 25, regardless of the state of the output of the comparison circuit 15. Then, the position adjustment motor 11 is stopped or reversed, and the protrusion amount l of the resistor 8 is left unchanged or reduced.

Effects of the Invention This invention provides a gate circuit between the basic control circuit and the drive circuit, connects the output ends of the rotation period reading device and the power supply frequency reading device to the pulse period comparison device, and connects the output terminals of the rotation period reading device and the power supply frequency reading device to the pulse period comparison device. Since it is connected to the gate circuit, when the rice milling motor approaches a no-load state during rice milling, the output pulse period of the rotation period reading device and the output pulse period of the power supply frequency reading device will satisfy the formula T ₁ ≒ PT ₂ /2N. When satisfied, a correction signal is output from the pulse period comparator.

Then, this correction signal enters the gate circuit to operate the drive circuit and reverse or stop the position adjustment motor, thereby adjusting the position of the resistor, regardless of the adjustment signal from the basic control circuit.

Therefore, even if the rice milling motor falls into a no-load state during operation, the amount of protrusion of the resistor does not become too large as in the conventional example. Motor overload can be prevented.

[Brief explanation of drawings]

1 to 4 are diagrams showing embodiments of the present invention, in which FIG. 1 is a longitudinal sectional view of a circulating rice mill, FIG. 2 is an enlarged sectional view of the mounting box in FIG. 1, and FIG. Figure 3 is an enlarged perspective view of the rotation period reading device in Figure 1;
The figure is a diagram showing a control circuit for the position adjustment motor. A... Circulating rice mill, B... Basic control circuit, 4
... Rice polishing motor, 8 ... Resistor, 11 ... Position adjustment motor, 17 ... Rotation period reading device,
21...Power frequency reading device, 22...Pulse period comparator, 24...Gate circuit, 25...
drive circuit.

Claims (1)

[Claims] 1. In a rice milling machine equipped with a basic control circuit that outputs an adjustment signal depending on the level of current value of the rice milling motor, a drive circuit connected to the basic control circuit, and a motor for adjusting the position of a resistor connected to the drive circuit, A gate circuit is provided between the basic control circuit and the drive circuit, and the output terminals of the rotation period reading device and the power supply frequency reading device are connected to a pulse period comparison device, and the output terminal of the pulse period comparison device is connected to the gate circuit. Automatic rice milling machine characterized by being connected.