JPS6256437B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drying control device for a grain dryer, and more particularly to a drying control device having a circuit for detecting contact failure of a changeover switch for setting a target moisture value of grain to be dried. .

The grain dryer is equipped with a changeover switch for selecting and setting the target moisture value of the grain to be dried, and converts the target moisture value set by switching the contacts of the switch to a DC level, and outputs the target moisture value. Through comparison between the detected moisture value of the dried grain and the corresponding DC level conversion output, drying control is performed so that the dried grain has a target moisture value.

By the way, grain dryers are not used all year round, but are only used during autumn and spring, and are often left unoperated for long periods of time. A contact failure may occur in the changeover switch for setting the target moisture value, such as when starting work. When this happens, the target moisture value is no longer given, and there is a risk that drying will not be completed even if the grain to be dried falls below the target moisture value.

The present invention has been made based on the above viewpoints, and
The purpose is to provide a drying control device that can prevent abnormal drying of grains to be dried due to contact failure of a target moisture value setting switch. A feature of the present invention for achieving this purpose is that it has a changeover switch that selects and sets a target moisture value of the grain to be dried;
In a drying control device for a grain dryer that terminates drying according to a comparison between a set target moisture value and a detected moisture value of the grain to be dried, a contact failure of the switch is detected based on a set output level of the changeover switch. A detection circuit is installed to display a contact failure according to the contact failure signal from the circuit, and a temporary target moisture value is set slightly higher than the normal target moisture value to prevent abnormal drying of the grain to be dried. It is found in the drying control device of a grain dryer like the one above.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the drying control device according to the present invention, in which 1 is a moisture meter, 2 is an average moisture value output circuit, 3 is a changeover switch for setting a target moisture value, 4 is a finished moisture value detection circuit, and 5 is a counter. , 6 is a contact failure detection circuit.

A moisture meter 1 grinds dried grains at predetermined intervals, converts the moisture value into an electrical signal, and outputs the electrical signal to an average moisture value output circuit 2. The average moisture value output circuit 2 calculates the average moisture value (n=1, 2, 3,...) using the formula,
= {4- ₁ +Msn}/5 (however, ₁ =
Ms ₁ ), output at DC level. Ms ₁ is the first detected moisture value output of moisture meter 1, ₁ is the first detected moisture value output.
Msn is the nth detected moisture value output of the moisture meter 1, _-1 is the n-1th average moisture value output, and Msn is the nth average moisture value output. The reason why the average moisture value is output in this way is because the moisture meter only detects the moisture value of a small portion of the grain to be dried, and there is variation in that value. In other words, this is to detect a more accurate moisture value. The changeover switch 3 for setting the target moisture value is connected to the DC source Vcc.
This is, for example, a rotary switch that outputs a DC level corresponding to a target moisture value by changing the resistance value. The finished moisture detection circuit 4 receives the outputs from the average moisture value output circuit 2 and the target moisture value setting changeover switch 3, and provides a pulse output every time the average moisture value≦target moisture value is satisfied. The counter 5 counts the output pulses of the finished moisture detection circuit 4, and gives a stop signal indicating that drying has ended when the pulses are counted five times in a row, for example. The burner combustion system and motor drive system of the dryer are stopped by the stop signal. On the other hand, the finished moisture detection circuit 4
If the output pulse is not applied five times in a row from then on, the dryer is reset by not applying the pulse, and therefore no stop signal is issued to the dryer. The contact failure detection circuit 6 has a comparator 601, which receives the DC output level of the target moisture value setting changeover switch 3 as its (-) input, and the reference value V is given to its (+) input. The reference value V of the comparator 601 is smaller than the lowest output level when the changeover switch 3 is set, and the comparator 601 outputs a contact failure signal when the reference value V>the output level of the changeover switch 3. On the output side of the contact failure detection circuit 6, there is an LED that indicates contact failure of the changeover switch 3.
and a buzzer can be generated.

With the above configuration, the target moisture value setting switch 3
If there is no contact failure and a DC level corresponding to the set target moisture value is output, the output level of the comparator 601 of the contact contact failure detection circuit 6 is "L" and no contact failure signal is output. On the other hand, if a contact failure occurs in the changeover switch 3,
Since its output level becomes 0, the reference value V of the detection circuit 6 becomes higher than the output level of the changeover switch 3, and the comparator 601 gives an "H" level output (a poor contact signal) to drive the LED and buzzer. . Incidentally, it is also possible to give the poor contact signal to the burner combustion and motor drive system of the dryer and use it to stop them.

The present invention provides a temporary target moisture value to the finished moisture detection circuit 4 when a contact failure occurs in the target moisture value setting changeover switch 3, and performs drying control of the grain to be dried based on the target moisture value. It's about making it happen.

That is, 7 is a reference value setting circuit that provides a DC level corresponding to a temporary target moisture value, and receives the "H" level signal (defect contact signal) output from the comparator 601 of the contact contact failure detection circuit 6 and sets the corresponding signal. The finishing moisture detection circuit 4
A temporary target moisture value is output. The tentative target moisture value is set to be slightly larger than the original finished moisture value of the grain to be dried. For example, the finished moisture value (target moisture value) for rice is 14.5 to 15.5.
%, but in this case, the tentative target moisture value is 17
% to ensure safety against overdrying. Therefore, according to this embodiment, even if a contact failure of the target moisture value setting switch 3 occurs, it is possible to dry the grain to be dried to a certain degree.

As explained above, according to the present invention, a circuit is provided to detect a contact failure of a changeover switch for setting a target moisture value, and an indication is provided in response to a contact failure signal of the circuit, and a temporary value slightly higher than a normal target moisture value is displayed. Since the target moisture value is set, if a contact failure occurs in the switch for setting the target moisture value, this defective condition can be detected immediately before the drying progresses. It is possible to maintain normal drying to a tentative target moisture value that is slightly higher than the target moisture value of , to perform drying efficiently and to prevent overdrying of the grain to be dried.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a drying control device according to the present invention. DESCRIPTION OF SYMBOLS 1... Moisture meter, 2... Average moisture value output circuit, 3... Changeover switch for setting target moisture value, 4... Finished moisture detection circuit, 5... Counter, 6... Contact failure detection circuit, 7... Reference value circuit.

Claims (1)

[Claims] 1. In a drying control device for a grain dryer, which has a changeover switch for selecting and setting a target moisture value of the grain to be dried, and finishes drying according to a comparison between the set target moisture value and the detected moisture value of the grain to be dried. , a circuit is provided to detect contact failure of the switch based on the set output level of the changeover switch, and a contact failure is displayed according to the contact failure signal of the circuit, and a tentative moisture value slightly higher than the normal target moisture value is displayed. A drying control device for a grain dryer, characterized in that a target moisture value is set to prevent abnormal drying of grain to be dried.