JPS6341307A - Choking preventing device for screw conveyor - Google Patents

Abstract

PURPOSE:To easily prevent the occurrence of choking, by a method wherein, when the motor current of a screw conveyor exceeds a given value, reversing and forward running of a motor are repeated for a given time at a time, and after repetition is effected the given number of times, the motor is restored to forward running. CONSTITUTION:When the overload of the current of a motor 1 of a screw conveyor is detected by means of an overload current detecting means 2, forward running of the motor 1 is stopped by means of a motor circuit switching means 5, and by switching the polarity or the phase of a power source, the motor 1 is reversed. When a time set by a forward running time set means 3 elapses, the motor 1 is brought into a forward running state. When a time set by means of a forward running time set means 4 lapses, the motor 1 is reversed again. The number of switching times is counted by means of a number of switching times means 6, and when the number of switching times is increased to a given value, the motor 1 is restored to forward running. This constitution enables easy prevention of choking of a screw.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a device for preventing clogging of a screw conveyor in a dust collector or the like.

[Background technology]

2. Description of the Related Art Conventionally, some dust collectors for collecting dust such as wood powder are equipped with a screw conveyor at the bottom of a hopper to move the dust input from the top of the hopper to a discharge port.

However, relatively large objects such as wood powder may get caught between the screw blade and the bottom wall of the hopper, causing the motor to stop due to overload. When a bite occurs like this,
The problem is that the operator has to manually remove the stuck object, which shortens the operating time and forces the operator to work under adverse conditions.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a screw conveyor clogging prevention device that can easily eliminate clogging even if clogging occurs and maintain normal operation of the screw conveyor.

[Disclosure of the invention]

The screw conveyor clogging prevention device of the present invention includes an overload current detection means for detecting that the current of the screw driving motor of the screw conveyor exceeds a set value, a reverse rotation time setting means, and a forward rotation time setting means. , 'I!' of the motor in response to the detection signal of the overload current detection means. ! A motor circuit switching means for alternately and repeatedly switching the connection state of the reverse rotation direction and the forward rotation direction for the set time of the source circuit gold circuit reverse rotation time setting means and the forward rotation time setting means, and a motor circuit switching means for repeatedly switching the connection state of the motor circuit switching means. The motor circuit includes a switching number counting means that counts the number of switching times and stops the repeated switching operation of the motor circuit switching means when a set number of times is reached, thereby bringing the motor circuit into a normal rotation state.

According to the configuration of the present invention, when the motor is overloaded due to a blockage in the screw conveyor, the overload current detection means detects that the motor current value exceeds the set value, and the motor circuit switching means detects that the motor current value exceeds the set value. Repeatedly switch the rotation between forward and reverse. The number of repetitions is set by the switching number counting means, and the normal normal rotation state is returned.

In this way, since the screw is rotated in the forward and reverse directions repeatedly a set number of times, even if the screw becomes clogged, the stuck object can be easily removed from the screw, and steady operation can be maintained.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 3. As shown in Fig. 1, this screw conveyor clogging prevention device consists of overload current detection means 2 that detects when the current of the screw drive motor l exceeds a set value.
In response to the detection signals of the reverse rotation time setting means 3, the forward rotation time setting means 4, and the overload current detection means 2, the power supply circuit of the motor 1 is adjusted to the set time of the reverse rotation time setting means 3 and the forward rotation time setting means 4. The motor circuit switching means 5 alternately and repeatedly switches the connection state in the reverse rotation direction and the forward rotation direction, and the number of times the motor circuit switching means 5 is repeatedly switched is counted, and when a set number of times is reached, the motor circuit switching means 5 repeatedly switches. It is equipped with a switching number counting means 6 for stopping the rotation and bringing it into a normal rotation state.

As shown in FIG. 2, the screw 7a of the screw conveyor 7 is provided at the bottom of the hopper 8.
A discharge port 9 is provided at the bottom of the hopper 8 at the I+ end. The discharge port 9 is connected to a silo or the like, and a filter is provided on the top surface of the hopper 8. The hopper 8 is used to input waste such as wood powder. The motor 1 is a three-phase motor, a capacitor motor, or the like.

FIG. 3 shows a specific example of the circuit shown in FIG.

In the figure, the MSR at address 1 is a reversing electromagnetic contactor that switches the power supply circuit of motor l to a reverse state, and the MS at address 4
F is a forward rotation electromagnetic contactor, and its ink lock contacts msr and msf are provided in series. xa and xb at addresses 1 and 9 are detector contacts, such as a meter relay, which serve as overload current detection means 2 (FIG. 1). T1 at address 2 is a timer serving as the reverse rotation time setting means 3, and has timer contacts Lla and Llb. T2 at address 5 is a timer serving as the forward rotation time setting means 4, and the timer contacts t2a,
Has t2b. CT at address 10 is switching number counting means 6
It is a counter, and aR1 to R1 that connect the counter contacts cta and ctb are relays, rl a, r2a, r
a and r3b are the relay contacts, respectively. S is a start switch such as the Bushu Japanese style.

motion An outline of the operation of the above configuration will be explained with reference to FIG.

When the motor is overloaded due to a blockage in the screw conveyor 7, the overload current detection means 2 detects that the motor current value exceeds the set value, and the motor circuit switching means 5 switches the rotation of the motor between forward and reverse directions. Switch repeatedly. The number of repetitions is the number set by the switching number counting means 6, and then the normal normal rotation state is returned.

In this way, since the screw 7a is rotated in the forward and reverse directions repeatedly a predetermined number of times, even if the screw 7a becomes clogged, the stuck object is easily removed from the screw 7a, and steady operation can be maintained.

Next, the operation of the circuit shown in FIG. 3 will be explained. In the following description, the symbols surrounded by circles indicate addresses in FIG. 3. When the start switch S■ is turned on, the relay R3 is excited and self-held by the relay contact r3a■, and the relay contact r3a■ is turned on. Therefore, relay R2 is energized and self-held at relay contact r2a, and forward rotation electromagnetic contactor MSF is turned on. Therefore, the motor 1 continues to rotate normally. This state is the normal operating state.

If the screw 7a (Fig. 2) is clogged and the current of the motor 1 exceeds the set value of the overload current detection means 2 (Fig. 1), the detector contact xb is turned off. The self-holding of the relay R3 is released and the relay contact r3a■ is turned off, so that the forward rotation electromagnetic contactor MSF■ is turned off. At the same time, detector contact xa■ is turned on, relay R1■ is energized, and is self-held by relay contact rla■. Therefore, the reversing magnetic contactor MSR is turned on, and the motor 1 continues to rotate in reverse. At this time, current also flows through the timer T1■, and when the set time of the timer T1 (for example, 3 seconds) is reached, the timer contacts t and b■ are turned off, and the self-holding of the relay R1 is released. Therefore, the reversing magnetic contactor MSR is turned off. Also, since the timer contact tea■ of timer TI is turned on at this time,
Relay R2■ is energized and self-held by relay contact r2a■. Therefore, the forward rotation electromagnetic contactor MSF■ is turned on, and the motor rotates in the normal direction again. When the forward rotation continues and the time set by the timer T2■ (for example, 3 seconds) has elapsed, the timer contact t2b■ is turned off, the self-holding of the relay R2 is released, and the forward rotation electromagnetic contactor MSF is turned off. At the same time, timer contact t2a■ turns on, and relay R
1 is energized and self-held as described above, and the reversing magnetic contactor MSR is turned on.

In this way, the reverse and forward rotations of motor 1 are controlled by timer T.
1 and T2 are alternately repeated for each set time. The number of repetitions is counted by the counter CT [phase] by the number of times the timer T1 is turned on. When the counter CT has counted up to the set number of times (for example, 3 times), the counter contact ctb■ turns off, and the counter contact cta
(2) is turned on, relay R3 is energized, and the normal normal rotation operation state described above is returned.

FIG. 4 is an electric circuit in another embodiment.

In the figure, MSR' and MSF' are electromagnetic contactors for reverse rotation and forward rotation of the motor, respectively.

msf' and mar' are the ink lock contacts. T
1' and T2' are timers, tla', which serve as reverse rotation time setting means and forward rotation time setting means, respectively.

t, b', t2' are +(D timer contacts. CT'
is a counter serving as a switching number counting means, and ctb' is a contact point of the counter. xa' and xb' are detector contacts of the overload current detection means 2 of the motor 1, respectively.

Although the motor circuit switching means 5 in each of the above-mentioned embodiments is composed of a beam control circuit, it may also be composed of a software circuit such as a microcomputer.

〔Effect of the invention〕

The screw conveyor clogging prevention device of the present invention detects that the motor current value exceeds a set value when the motor is overloaded due to a screw conveyor clogging, and the motor circuit switching means detects that the motor current value exceeds a set value. The rotation of the motor is repeatedly switched between forward and reverse directions. The number of repetitions is the number set by the switching number counting means, and this l & normal forward rotation state is established.

In this way, since the screw is rotated in the forward and reverse directions repeatedly a set number of times, even if the screw becomes clogged, the stuck object can be easily removed from the screw, and steady operation can be maintained.

[Brief explanation of the drawing]

Fig. 1 is a circuit block diagram of one embodiment of this invention, Fig. 2 is a schematic perspective view of the screw conveyor, Fig. 3 is a specific circuit diagram thereof, and Fig. 4 is a circuit diagram of another embodiment. be. ■...Motor, 2...Overload current detection means, 3...
・Reverse rotation time setting means, 4... Forward rotation time setting means, 5.
... Motor circuit switching means, 6... Switching number counting means,
7...Screw conveyor, 7a...Screw patent applicant National Housing Industry Co., Ltd. Agent Patent attorney Akio Miyai'-:,-□fu...,,゛-12,',',: ,=ze

Claims (1)

[Claims] an overload current detection means for detecting that the current of a motor for driving a screw of a screw conveyor exceeds a set value; a reverse rotation time setting means; a forward rotation time setting means; and a detection signal of the overload current detection means. a motor circuit switching means for responsively switching the power supply circuit of the motor alternately and repeatedly between connection states of a reverse rotation direction and a forward rotation direction for a time set by the reverse rotation time setting means and the forward rotation time setting means; and the motor circuit switching means. A device for preventing clogging of a screw conveyor, comprising a switching number counting means for counting the number of repeated switching operations of the motor circuit switching means and stopping the repeated switching operation of the motor circuit switching means when a set number of switching operations is reached, and setting the motor circuit switching means to a normal rotation state.