JPS6221436Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electric motor overload protection device for a meat cutter, and more particularly to an electric motor overload protection device suitable for preventing burnout of the electric motor that reciprocates a meat box containing meat loaves. It is something.

Conventionally, when cutting a frozen meat loaf with a meat cutter, the round blade's cutting load resistance increases depending on the size of the meat loaf and the degree of freezing, and in some cases, the rotation of the round blade becomes difficult. At the same time, the movement of the meat box also stopped, and the round blade and meat box driving electric motor were sometimes locked, and there was a risk that the motor would burn out.

In addition, in order to release the motor from the locked state and prevent the motor from burning out, the operator must operate the power switch or operation switch to cut off the power supply to the motor, and the operating state must always be maintained on the main unit. It was necessary to stand by and watch.

The present invention has been made in view of the above, and its purpose is to provide a motor overload protection device for a meat cutter that can prevent burnout of the round blade of the meat cutter and the electric motor for driving the meat box. It's about doing.

The features of the present invention include a current detector that detects the load current of the round blade and the meat box drive motor during the cutting operation of the meat loaf, a voltage conversion circuit that rectifies and smoothes the electrical signal from this current detector, A voltage comparison circuit that compares the output voltage of the voltage conversion circuit with a reference voltage set in advance according to the restricted current of the motor, and a voltage comparison circuit that generates an output signal of the voltage comparison circuit until a predetermined setting time is reached. The present invention further comprises a means for cutting off power supply to the electric motor via a drive control circuit for the electric motor when the electric motor is activated.

The present invention will be explained in detail below with reference to the embodiments shown in FIGS. 1 and 2 and FIG. 3.

Fig. 1 is a front view showing one embodiment of a meat cutting machine equipped with an electric motor overload protection device according to the present invention. In Fig. 1, reference numeral 1 denotes a support member, on the upper surface of which two parallel sliding members 2 are arranged, and a meat box 3 is supported and fitted on the sliding members 2 so as to be capable of reciprocating (in the front-rear direction in the drawing). One end of an arm 4 is rotatably supported on the bottom of the meat box 3,
The other end of the arm 4 is rotatably supported by a crank 5. A meat box drive motor 6 is connected to a reducer 7 via a continuously variable speed means (not shown).
The output shaft of the reduction gear 7 is fitted with a crank 5. Therefore, the reduction gear 7 is rotated by the rotation of the electric motor 6.
The crank 5 rotates via the arm 4, and the meat box 3 reciprocates via the arm 4. The circular blade 8 is rotated by the electric motor 6 via a power transmission means such as a gear or a belt. 9 is an operation switch. By operating the operation switch 9, the circular blade 8 is rotated.
The cutting machine is rotated and the meat box 3 is reciprocated, so that the chunks of meat stored in the meat box 3 are cut continuously or intermittently by the round blade 8.

FIG. 2 is a block diagram showing an embodiment of the motor overload protection device of the present invention. In Figure 2,
10 is a current detector that detects the load current of the electric motor 6 during the cutting operation of the meat block stored in the meat box 3; 11;
1 is a full-wave rectifier circuit, 12 and 13 are resistors, and 14 is a capacitor, which constitute a voltage conversion circuit that rectifies and smoothes the output signal of the current detector 10 and converts it into a DC voltage. 15 is a comparison circuit consisting of a comparator that compares the DC voltage from the voltage conversion circuit with the reference voltage Vref; 16 is a comparator 1;
A timer that operates at the rising edge of the output signal of 5, 1
7 is a D flip-flop which transmits the input signal of the D input terminal to the o output terminal at the falling edge of the output signal of the timer 16; 18 is the o of the D flip-flop 17;
The drive control circuit 19 is cleared by the output signal from the output terminal, and is an amplifier circuit that amplifies the output signal of the drive control circuit 18 and excites the relay coil 20. 20a is a normally open relay contact that closes when the relay coil 20 is excited, and is connected in series between the electric motor 6 and its power sources R, S, and T.

FIG. 3 is a time chart of various signals in FIG. 2. The operation shown in FIG. 2 will be explained below with reference to FIG. Now, during the cutting operation of the frozen meat loaf, the cutting resistance of the meat loaf by the round blade 8 (see Fig. 1) has increased, the meat box 3 is about to stop moving or has stopped, and the load current of the electric motor 6 has increased. Consider the case. In this case, the output signal a of the current detector 10 changes as shown in FIG. 3A. This output signal a
is rectified by a full-wave rectifier circuit 11 as shown in FIG. 3B, and further smoothed by resistors 12 and 13 and a capacitor 14, and converted into a DC voltage C as shown in FIG. 3C. This output voltage c is the reference voltage
When the voltage exceeds Vref, the output signal d of the comparator 15 is inverted from logic "L" to logic "H" as shown in FIG. 3D. The timer 16 operates at the rising edge of this inverted signal, and the output signal e of the timer 16 becomes logic "H" for a set time _T1 as shown in FIG. 3E. Next stage D flip-flop 17
In this case, the output signal d of the comparator 15 is
If the set time T is logic "H" for more than ₁ , the output signal f from the output terminal o becomes logic "L" at the fall of the output signal e of the timer 16 as shown in FIG.
become. When the output signal f of the D flip-flop 17 becomes logic "L", the drive control circuit 18 is cleared, and the output signal g of the drive control circuit 18 changes from logic "H" to logic "L" as shown in FIG. Become.
Therefore, the excitation of the relu coil 20 is stopped,
The normally open relay contact 20a is opened, and the power supply to the motor 6 is cut off.

Here, the set time _T1 of the timer 16 is set to be longer than the time during which the starting current flows so that the next stage circuit will not operate due to the starting current of the motor 6 at the start of cutting work.

Furthermore, if the overload state of the motor 6 is released within the set time _T1 of the timer 16, the output voltage C of the voltage conversion circuit becomes lower than the reference voltage Vref, so the output voltage d of the comparator 15 is The output signal f on the terminal o side of the D flip-flop 17 maintains the logic "H" state, and the cutting operation of the meat block continues.

Note that the reference voltage Vref is set to correspond to a current value slightly smaller than the restraint current of the electric motor 6.

According to the embodiment of the present invention described above, the load current of the electric motor 6 during the meat cutting operation is detected, and if the overload condition continues for a set time T1 _or more, the power circuit of the electric motor 6 is cut off. Therefore, even if the electric motor 6 is in a restricted state when cutting the frozen meat, it is possible to prevent the electric motor 6 from burning out, and the safety of the cutting operation can be improved. Further, it is no longer necessary for the operator to constantly monitor the operating state of the meat cutter body, and the labor burden on the operator can be reduced.

In the above embodiment, a meat cutting machine in which the round blade 8 and the meat box 3 are driven by one electric motor 6 has been described, but a meat cutting machine having a round blade driving electric motor and a meat box driving electric motor is also applicable. In this case, it is sufficient to install a current detector on each motor so that when one motor becomes locked, the power supply to both motors is cut off, and the same effect can be obtained. can.

As explained above, according to the present invention, it is possible to prevent burnout even if the round blade of the meat cutter and the electric motor for driving the meat box are in a locked state, improving the safety of cutting work and This has the effect of reducing labor burden.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of a meat cutter equipped with a motor overload protection device according to the present invention, and FIG. 2 is a front view showing an embodiment of the motor overload protection device for a meat cutter according to the present invention. The block diagram, FIG. 3, is a time chart of the various signals in FIG. 2. 3...Meat box, 6...Electric motor, 8...Round blade, 10
...Current detector, 11...Full wave rectifier circuit, 12,
13...Resistor, 14...Capacitor, 15...Comparator, 16...Timer, 17...D flip-flop, 18...Drive control circuit, 20...Relay coil, 20b...Normally open relay contact.

Claims (1)

[Scope of utility model registration request] A meat cutter that reciprocates a meat box containing meat chunks through a crank mechanism by the output shaft of a speed reducer that decelerates the rotation of an electric motor, and cuts the meat chunks using a rotary blade. , a current detector for detecting the load current of the motor during the cutting operation of the meat, a voltage conversion circuit for rectifying and smoothing the electrical signal from the current detector, and a voltage comparison circuit that compares the magnitude of a set reference voltage and the output voltage of the voltage conversion circuit; and a drive control circuit for the motor when the generation time of the output signal of the voltage comparison circuit reaches a predetermined setting time. An electric motor overload protection device for a meat cutter, comprising means for cutting off power supply to the electric motor via the electric motor.