JPH0842971A - Overload detector for motor in circulation type grain dryer - Google Patents

Abstract

PURPOSE:To detect the values of current in respective motors correctly in accordance with actual loads even when an outside temperature of the circumference of a dryer is reduced or a temperature in a control box is increased due to the elapse of operating time of the dryer. CONSTITUTION:An overload detecting device is provided with a current detector 32, detecting a load current interposed in a power supply 31 for a motor 29 driving respective parts of a drier, a temperature sensor 37, measuring an ambient temperature near said current detector 32, and a controller 36, operating a corrected current value obtained by correcting the current value, detected by the current detector 32, by the ambient temperature, detected by the temperature sensor 37, and stopping the operation of the motor 29 when the corrected current value has arrived at a set value, set arbitrarily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor overload detection device for a circulating grain dryer.

[0002]

2. Description of the Related Art A circulating grain dryer comprises a storing section, a drying section and a grain collecting section. The grain collecting section communicates with a storing section through a grain lifting machine to form a circulating grain stroke, and a conveyor. It is driven by an electric motor, a grain elevator motor, a discharge valve motor, and the like. Then, after the grain put into the storage section is dried in the drying section, it is intermittently supplied to the grain collecting section by the discharge valve provided below the drying section, and is fed from the grain collecting section by the grain lifting machine, It is circulated until a predetermined water content is reached.

In the circulation type grain dryer as described above,
A current transformer (CT) as an overload detection sensor is provided in each motor that drives the conveyor, the grain elevator, the discharge valve, and the blower. The current transformer detects the load current value of each motor and inputs the detection signal to the control device. And
When the control device determines that the detected current value is greater than or equal to the set current value, the output signal from the control device opens the electromagnetic switch intervening in the current of the motor to stop the operation of the motor. Burnout due to load is prevented (see Japanese Patent Laid-Open No. 4-359624).

[0004]

However, the current transformer which detects the overload of each motor in the above-mentioned circulation type grain dryer is housed in the control box together with the control device and the like. When the outside air temperature around the circulation type grain dryer suddenly dropped, the output of the detection signal of the current transformer was lowered, which delayed the actual overload. Further, even when the temperature in the control box rises due to the passage of the operating time of the circulation type grain dryer, the output of the detection signal is lowered and a delay occurs with respect to the actual overload. That is, the current transformer that detects the overload of each motor has a temperature characteristic depending on the material, and is at room temperature (20 ° C to 3 ° C).
This is because it is supposed to be used at 0 ° C. (see FIG. 5).

The present invention solves the above-mentioned drawbacks of the conventional apparatus, and when the outside air temperature around the circulation type grain dryer is lowered, or the operating time of the circulation type grain dryer elapses, the control box is kept in the control box. It is a technical object to provide a motor overload detection device in a circulating grain dryer that can accurately detect the current value of each motor in real time even when the temperature rises.

[0006]

In order to solve the above problems, the present invention relates to a storage section for storing a material to be dried, a drying section provided below the storage section, and a lifting section for connecting the drying section and the storage section. In a circulation type grain dryer that forms a grain circulation process with a grain machine, a current detector that detects a load current interposed in the power source of a predetermined motor that drives each part of the dryer, and an ambient temperature near the current detector A temperature sensor that measures the temperature and the current value detected by the current detector are corrected by the ambient temperature detected by the temperature sensor to calculate a correction current value, and the correction current value reaches an arbitrarily set value. A technical means has been taken to provide a control device for stopping the operation of the predetermined motor at times.

Further, the control device discriminates the correction current value into an arbitrarily set class, and when the cumulative value of the coefficient set for each discriminated class reaches an arbitrarily set set value, It is effective to stop the operation of the motor.

[0008]

[Function] When the grain stored in the storage unit of the circulation type grain dryer flows down the drying chamber provided in the drying unit, the drying air blown by the hot air generator is dried by passing through the drying chamber. It In this circulation type grain dryer, the detected value from the current detector interposed in the power source of the motor and the temperature sensor provided in the vicinity of the current detector are respectively input to the control device, and the detected current value is converted into the current by the control device. The corrected current value is calculated by being corrected by the ambient temperature near the detector. Then, the correction current value is discriminated into a class set arbitrarily, and when the cumulative value of the discriminated coefficients reaches the set value,
The motor operation is stopped.

[0009]

EXAMPLE FIG. 2 is a partial front sectional view of a circulating grain dryer. Reference numeral 1 denotes a circulation type grain dryer, which is provided with a storage unit 2 for storing a material to be dried, a drying unit 3 below the storage unit 2, and a drying unit 3 and the storage unit 2 are connected to one side thereof. The grain machine 4 is erected to form a grain circulation process. The drying section 2 is provided with a drying chamber 5, a hot air chamber 6 and an exhaust chamber 7 which are partitioned by a perforated wall plate. The upper part of each drying chamber 5 communicates with the storage part 2 and the lower part of each drying chamber 5 is a grain. We are in contact with Downstream Route 8. The grain flow-down path 8 is connected to a grain collecting trough 10 via a discharge valve 9, and a lower carrier 11 is provided at the bottom of the grain collecting trough 10.
The lower carrier 11 is a grain elevator 4, an upper carrier 12, and a scattering plate 1.
It is communicated with the storage unit 2 via 3. A moisture measuring device 15 is further provided on one side of the fried machine 4 via the supply cylinder 14, and the grain is in the bucket 1 between the belts 16 and 16 of the fried machine 4.
7 is fed from a guide plate 18 which collects the return grain from 7. The moisture measuring device 15 communicates with the bottom of the fried machine 4 via the discharge gutter 19 and the return gutter 20. Reference numeral 21 is a grain-driving machine drive motor.

FIG. 3 is an enlarged view showing the drive unit of the circulating grain dryer. Reference numeral 22 denotes a discharge valve driving device, which includes sprockets 23, 23 attached to the shafts of the discharge valves 9, 9, a sprocket 25 attached to a discharge valve driving motor 24, a tension sprocket 26, and a chain 27.
Wind up. Further, the pulley 28 attached to the shaft of the lower conveyance machine 11 and the lower conveyance machine drive motor 29 are connected by a belt 30.

Next, a circuit diagram of the motor overload detection device will be described with reference to FIG. A current transformer (CT) that detects a load current in a power supply 31 of a lower transporter drive motor 29 (the same applies to the motor 21 and the motor 24).
The current transformer 32 communicates with a CPU 36 that calculates various input values via an amplifier 33, an AD converter 34, and an input / output circuit 35, with 32 interposed. Further, a temperature sensor 37 for detecting the ambient temperature of the current transformer 32 is provided near the current transformer 32, and the CPU 3 is connected via the AD converter 34 and the input / output circuit 35.
Call 6. The output signal 39 from the CPU 36 intervenes in the power source 31 of the motor 29 to drive the motor drive circuit to "O".
It is in contact with the electromagnetic switch 38 that is "N" or "OFF". Reference numeral 40 is a storage device composed of ROM and RAM, reference numeral 41 is a drying switch, reference numeral 42 is a discharge switch, and reference numeral 43 is a stretch switch.

Next, the operation of the above structure will be described.
Grain (for example, paddy) supplied to a hopper (not shown)
The grain is lifted by the grain elevator 4, passes through the upper transporter 12, and is evenly scattered and accumulated in the reservoir 2 from the scattering plate 13. Next, when the hot air generator (not shown) and the exhaust fan (not shown) are operated to rotate the exhaust valve 9, the grains in the storage portion 2 flow laterally from the hot air chamber 6 to the exhaust air chamber 7. Hot air is dried by the dry air, and the dry air is discharged from the air exhaust chamber 7 to the outside of the machine by an air exhaust device (not shown). Grains that have been hot-air dried by the dry air flow down through the grain flow path 8 and are intermittently discharged by the discharge valve 9. The discharged grain flows down the discharge gutter 10 and is sent to the grain fried machine 4 by the lower transfer device 11 and is put into the storage part 2 again, and is circulated and dried until the moisture measuring device 15 detects a predetermined moisture.

Grains to be transported by the grain elevator 4 spill from the bucket 17 between the belts 16 and 16 due to vibration during transportation. The spilled grain is collected by the guide plate 18, flows down from the guide plate 18 through the supply cylinder 14 and is supplied to the moisture measuring device 15, where the moisture of the grain is measured. The grain whose moisture has been measured is discharged from the moisture measuring device 15, flows down the discharge gutter 19, and is supplied from the return gutter 20 to the lower part of the grain elevator 4.

Next, the operation of the motor load detector will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart of the CPU 36 embodying the present invention. Step 101
Press one of the operation buttons for loading, drying, and discharging with
In step 102, the lower transporter drive motor 29 is driven. Then, in step 103, a timer having a delay time of 6 seconds is operated to obtain a stable detected current value after the motor is started, and in step 104, the detected current value and the ambient temperature of the current transformer 32 are sampled every one second. Activate the timer. When each of the above timers is activated, step 105 is reached and the CPU 36 is instructed to set the ambient temperature t of the current transformer 32.
Is read and stored in the storage device 40. Next, at step 106, the detected current value CT ₁ of the motor 29 is set to the CPU
36. The detected current value CT ₁ read by the CPU 36 is subjected to temperature correction in step 107. This will be described in detail with reference to FIG.

FIG. 5 is a diagram showing the temperature characteristics of the current transformer 32. As shown in this figure, in the conventional current transformer 32, with the temperature of 25 ° C. as a boundary, the detected current value becomes smaller than the actual load current value as the temperature becomes lower, and the detected current value becomes higher as the temperature becomes higher. It tends to be larger than the actual load current. Therefore, the present invention intends to correct the detected current value to the actual load current value regardless of the temperature. In FIG. 5, for example, the detected current value may be converted into the corrected current value using the following correction formula.

[0016]

[Equation 1] For example, the detected current value CT ₁ when the temperature t is 0 ° C. is 2.
If it is 30 A, the correction current value CT _C is CT _C = C
T ₁ + Y = 2.30 + 0.39 = 2.69 A, and the detected current value CT ₁ when the temperature t is 30 ° C. is 2.7.
If it is 4 A, the correction current value CT _C is CT _C = CT
₁ + Y = 2.74−0.05 = 2.69 A, and it can be seen that the detected current value is corrected to the actual load current value regardless of the temperature level.

Returning to the flowchart of FIG. 4, the operation of the motor load detecting device will be described. When the correction current value is calculated in step 107, the process proceeds to step 108 and the rated current value of the motor is compared with the correction current value to determine whether or not the motor is overloaded. If it is determined that the motor is not overloaded, the process returns to step 104 and the above steps are repeated. If the motor is determined to be overloaded, then step 1
09 overload ratio determination means.

The overload ratio determining means 109 is a current transformer 32 as disclosed in Japanese Patent Laid-Open No. 4-359624.
Even if the correction value CT _C of the detected current value CT ₁ is temporarily determined to be the set current value or more, the motor operation is immediately stopped and the drying operation is not interrupted. This control will be described below.

When the set value-coefficient value x time (seconds) = 0 in the storage device of the CPU (step 110), the overload of the current transformer 32 is displayed as an alarm and the electromagnetic switch 3 is operated.
8 is opened to set the motor drive circuit to "OFF" (step 111). Although the set value and the coefficient value can be arbitrarily set, in the present embodiment, the set value is 1000
The coefficient values are shown in Table 1.

[0020]

[Table 1] That is, the correction value of the detected current is determined for each class from 120% to 200% of the rated current (step 112 to step 115), and the cumulative value of the coefficient set for each determined class (step 116 to step 120). )
However, when the set value (C = 0) set arbitrarily is reached, the operation of the motor is stopped (step 111).

In this embodiment, the current sensor 3 is provided with the temperature sensor 37 for measuring the ambient temperature near the current transformer 32.
Although the detected current value of 2 is corrected by the ambient temperature, the impedance of the current transformer 32 may be measured to correct the decrease in the output of the current transformer 32.

[0022]

According to the circulation type grain dryer of the present invention, the current detector for detecting the load current interposed in the power source of the predetermined motor for driving each part of the dryer and the ambient temperature near the current detector are controlled. When the temperature sensor to be measured and the current value detected by the current detector are corrected by the ambient temperature detected by the temperature sensor to calculate a correction current value, and the correction current value reaches a set value set arbitrarily. Since a control device for stopping the operation of the predetermined motor is provided in, even when the outside air temperature of the dryer is lowered, or even when the temperature in the control box rises due to the elapsed operating time of the dryer,
It has become possible to accurately detect the current value of a predetermined motor in real time.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a motor overload detection device.

FIG. 2 is a partial front sectional view of a circulating grain dryer.

FIG. 3 is an enlarged view showing a drive unit of a circulation type grain dryer.

FIG. 4 is a flowchart of a CPU that implements the present invention.

FIG. 5 is a diagram showing temperature characteristics of the present invention and a conventional current transformer.

[Explanation of symbols]

 1 Circulating Grain Dryer 2 Storage Section 3 Drying Section 4 Lifting Machine 5 Drying Room 6 Hot Air Chamber 7 Exhaust Chamber 8 Grain Downflow Path 9 Discharge Valve 10 Grain Gutter 11 Lower Conveyor 12 Upper Conveyor 13 Scattering Plate 14 Supply Cylinder 15 Moisture measuring device 16 Belt 17 Bucket 18 Guide plate 19 Discharge gutter 20 Return gutter 21 Lifter drive motor 22 Discharge valve drive device 23 Sprocket 24 Discharge valve drive motor 25 Sprocket 26 Tension sprocket 27 Chain 28 28 Pulley 29 Lower carrier Drive motor 30 Belt 31 Power supply 32 Current transformer 33 Amplifier 34 AD converter 35 Input / output circuit 36 CPU 37 Temperature sensor 38 Electromagnetic switch 39 Output signal 40 Storage device 41 Drying switch 42 Ejection switch 43 Expansion switch

Claims (2)

[Claims] 1. A circulation type grain drying device in which a grain circulation step is formed by a storage unit for storing a material to be dried, a drying unit provided below the storage unit, and a grain elevator connecting the drying unit and the storage unit. In the machine, a current detector for detecting a load current interposed in a power source of a predetermined motor for driving each part of the dryer, a temperature sensor for measuring an ambient temperature in the vicinity of the current detector, and a current sensor for detection. A controller for calculating a corrected current value by correcting the current value with the ambient temperature detected by the temperature sensor, and stopping the operation of the predetermined motor when the corrected current value reaches an arbitrarily set value. An overload detection device for a motor in a circulating grain dryer, which is characterized by being provided. 2. The control device discriminates the correction current value into an arbitrarily set class, and when the cumulative value of the coefficient set for each discriminated class reaches the arbitrarily set set value, the above-mentioned each The overload detection device for a motor in a circulating grain dryer according to claim 1, wherein the operation of the motor is stopped.