JPS5930392Y2 - Automatic hot air temperature control device in grain dryer - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to an automatic hot air temperature control device for drying grain in a grain dryer, and in particular, a device that controls the temperature according to outside air conditions and the amount of paddy put in. Regarding.

Conventional technology Conventionally, when controlling the hot air temperature, the hot air temperature is set by taking into consideration the initial moisture content of grain, the amount of grain processed, and the temperature and humidity of the surrounding outside air. The combustion amount of the hot air generator was controlled so that it always matched the set temperature regardless of changes in outside air conditions.

As for the temperature and humidity of the outside air, it was common practice to consider the statistical classification of late summer, early autumn, and late autumn without installing any particular sensor.

This makes it difficult to meet the exceptional conditions within that category, making it troublesome for general farmers to set the hot air temperature.

Therefore, in order to solve this problem, an outside temperature sensor was installed, considering that if the outside temperature is detected, the temperature condition of the outside air is also established. Attempts were made to automatically control the temperature of hot air to be reset.

However, if such a means is modified, the temperature of the hot air will be controlled in response to subtle changes in the outside temperature, which will instead become unstable, which is not preferable.

Problems and Means to be Solved by the Invention In view of these circumstances, the invention aims to avoid being affected by the hot air temperature in response to slight changes in the outside air throughout the day, and to reduce the influence of the seasonal outside air temperature, which is larger than the hot air temperature. An object of the present invention is to provide an automatic hot air temperature control device for a grain dryer that is improved so as to automatically control the hot air temperature only in response to changes in the temperature of the grain dryer.

EXAMPLE Hereinafter, an example of the present invention will be specifically described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a DC power supply section, and 2 a temperature comparison circuit. In this temperature comparison circuit 2, a thermistor Th for detecting hot air temperature is connected to the base of a transistor Tr.

On the other hand, a control device 3 for the outside temperature, a control device 4 for the amount of paddy put in, a variable resistor VR1, and a resistor R are connected in series and connected to the emitter of the transistor Tr,
A collector current is drawn from the transistor Tr by comparing the internal resistance value of the thermistor Th with the resistance value on the side of the control devices 3 and 4.

The current from the transistor Tr is passed through the variable resistor VH2 for adjusting the highest frequency of the switch SW1 to the capacitor C1.
A current also flows from the variable resistor VR3 for adjusting the lowest frequency to charge the capacitor C1, and the charging voltage at that time is input to the program unijection transistor PUT, from which a pulse of a predetermined frequency is generated. enters the gate of thyristor Q1 and turns it on.

As a result, the coil L of the electromagnetic pump P is excited, but at the same time, each time the commutation capacitor C2 discharges through the thyristor Q1, the other thyristor Q2 is turned off, and at the same time, the pulse width is energized through the variable resistor VR4 for adjusting the pulse width. Current flows through capacitor C3.

Then, when that capacitor C3 charges and diac D turns on, a pulse enters the gate of thyristor Q2 and turns it on, and thyristor Q! is turned off and the coil L is demagnetized.

In this way, thyristors Ql and Q2 are turned on. By repeatedly turning off the coil L, the coil L is intermittently excited at a predetermined time interval, and the electromagnetic pump P supplies combustion oil to the combustor.

By the way, as detailed in FIG. 2, the control device 3 for controlling the outside temperature includes a fixed resistor r1, a thermostat Tsl connected in parallel to short-circuit it, a resistor r2 connected in the same way, and a thermostat TS2X resistor. r3 and thermostat Ts 3, resistor r4 and thermostat) Ts
4 are connected in series, respectively.The thermostats Tsl to Ts 4 operate in response to changes in the outside temperature, and their respective operating temperatures (on) and return temperatures (off) are determined by, for example, the third thermostat. The settings are as shown in the figure.

In other words, in the case of the thermostat Tsl, it turns on when the temperature exceeds 32°C and does not turn off unless the temperature falls below 22°C, and in the case of the thermostat Ts2, it turns on when the temperature exceeds 27°C, which is between the above temperatures, and from that point on. It will not turn off unless the temperature drops by 10℃ to 17℃ or below (hereinafter referred to as thermostat) Ts3. Similarly, in the case of Tsz, it is specified that it should turn on at 22°C or higher, turn off at 2°C or lower, turn on at 17°C or higher, and turn off at 7°C or lower.

As a result, when the outside temperature is above 32°C, all thermostats (Tsl to Ts4) turn on and resistors r1 to r
4 is short-circuited, the resistance value of the control device 3 becomes the minimum zero, and then when the outside temperature drops below 22° C., only the thermostat Tsl is turned off and the resistance value of the control device 3 becomes rl.

When the outside temperature drops below 17℃, the thermostat T
sl and Ts2 are turned off, and the resistance value of the control device 3 becomes resistance r1.
When the temperature drops below 12°C, only the thermostat Ts4 turns on, and the resistance value of the control device 3 becomes the sum of the resistors rl to r3, and when the temperature drops below 7°C, all the thermostats Ts1 to Ts4 turn on. is turned off and the resistance value of the control device 3 becomes resistance r1. to the maximum sum of r4.

In FIG. 3, the arrow indicates the direction of hysteresis.

Thus, since the present invention is configured as described in 5 above, when the hot air temperature increases, the internal resistance value of the thermistor Th decreases, the bias voltage of the transistor Tr decreases, and thereby its collector current also decreases.

Therefore, the charging time of the capacitor C1 becomes longer and the frequency of pulse generation from the transistor PUT becomes smaller.
The driving frequency of the electromagnetic pump P also decreases, and the amount of fuel oil discharged decreases.

Conversely, when the hot air temperature decreases, the collector current of the transistor Tr increases due to the increase in the internal resistance of the thermistor Th, and the charging time of the capacitor C1 becomes shorter. Therefore, the frequency of pulse generation from the transistor PUT decreases. As the fuel oil becomes larger, the driving frequency of the electromagnetic pump P also increases, and the discharge amount of fuel oil increases.

In this way, the hot air temperature is controlled to match the set temperature.

In such hot air temperature control, when the outside temperature is 32°C or higher, the resistance value of the control device 3 becomes the minimum value of zero, so the collector current of the transistor Tr increases, which causes the electromagnetic pump to The driving frequency of P increases, the amount of fuel oil discharged also increases, and the hot air temperature is set high.

By the way, the change in outside temperature during the day is about 8 to 12 degrees Celsius, and if the outside temperature changes from the above condition to 25 degrees Celsius due to subtle temperature fluctuations, for example, the hysteresis of the thermostat causes Tsl to Ts4 is ON, the resistance value of the control device 3 remains unchanged at zero, and the hot air temperature is maintained at the above-mentioned high temperature state.

Next, the outside temperature changes significantly seasonally, for example, 25
℃ to 10℃, the control device 3
At this time, thermostats )'l's1 to Ts4 change from being on to only thermostat Ts4 being on.

Therefore, the resistance value increases to (r10r2+r3+r4) and the collector current of the transistor Tr decreases, thereby reducing the drive frequency of the electromagnetic pump P and the discharge amount of fuel oil, and the hot air temperature is set low.

In addition, when the control device 4 changes the resistance value with respect to the amount of paddy being put in so that the resistance value decreases as the amount of paddy being put in increases, the hot air temperature also increases or decreases in response to the increase or decrease in the amount of paddy being put in. controlled.

Foreshadow effect As explained above, according to the present invention, seasonal differences in outside temperature are taken into account as hot air temperature setting factors, while - hot air temperature is adjusted without being affected by subtle temperature fluctuations during the day. This makes it possible to control and ensure stability.

If the weather is initially cloudy and the temperature is high, but the weather clears up after midnight and the temperature suddenly drops, this naturally causes the hot air temperature detected by the control device 3 to drop. This prevents overflow in a combustor such as a pot burner.

Furthermore, the hot air temperature at the start of drying is automatically determined based on the highest and lowest outside temperatures for about a day immediately before the start, so there is no need for the operator to take any consideration.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the device according to the present invention, FIG. 2 is a circuit diagram showing main parts in detail, and FIG. 3 is a diagram showing settings of the operating temperature and return temperature of the thermostat. 1...DC power supply, 2...Temperature comparison circuit, 3, 4...Control device, Th...Thermistor, Tr...Transistor , VRl to VH2...variable resistor, SW...switch, C1 to C3...capacitor, PUT...
...Programmable transistor, Ql, Q2 ... Thyristor, D ... Diac, P ... Electromagnetic pump, L ... Coil, rl or r4...
...Resistance, Tsl to Ts4...Thermostat.

Claims (1)

[Scope of utility model registration request] In the temperature comparison circuit that compares the internal resistance value of the thermistor for hot air temperature detection with the resistance value of the variable resistor for hot air temperature setting and obtains a signal corresponding to the hot air temperature, a fixed short circuit it with the resistor
A predetermined temperature range is set between the operating temperature and the reset temperature of the plurality of thermostats that operate in response to changes in the outside temperature. Allow hysteresis to form,
An automatic hot air temperature control device for a grain dryer, characterized in that only when the outside temperature changes significantly, the resistance value of the entire fixed resistor group is changed to adjust the signal from the temperature comparison circuit.