JPS5947830B2 - Grain dryer drying air temperature control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drying air temperature control device for a grain dryer.
In particular, the present invention relates to a drying air temperature control device for a grain dryer that prevents the drying air temperature from rising rapidly when the drying air volume is reduced.

From the viewpoint of energy saving or prevention of quality deterioration of the material to be dried, recently, the air volume is sometimes reduced during the drying process.

However, with conventional drying air temperature control devices, it is not possible to reduce the combustion amount of the burner in response to the drying air volume reduction operation, and a drying air with a temperature higher than the normal drying air temperature is generated at this time. As a result, the material to be dried is exposed to high-temperature drying air, resulting in deterioration of the quality of the material to be dried, and the user is inconvenienced in that the burner flame spreads, making the user unnecessarily anxious.

That is, as shown in Fig. 6, the drying air volume changes from A1 to A.
2, the conventional control device reduces the oil supply amount from ■1 to ■2, but p.

Since the gradual decrease graph of qy r was followed, the drying air temperature Tb is within the set temperature range Tc, as shown by the dotted line batches P, Q, and H.
It goes out of control.

Incidentally, the above-mentioned disadvantages are caused by a delay in the response of the temperature sensor to a temperature change, a delay in the combustion response of the burner, and the like.

In particular, in consideration of the response delay of the temperature sensor and burner combustion mentioned above, the temperature of the drying air is input every sampling period, and the temperature is controlled by regulating the amount of oil sent to the burner so that the set temperature is always reached. In a wind temperature control device, the control cannot immediately respond to a sudden increase in the drying air temperature from the set temperature that occurs due to the air volume reduction operation that ends in a relatively short time, and after a response delay, the temperature is controlled again to the set temperature. The abnormally high temperature dry air will continue to be emitted for a period of time, further increasing the above-mentioned inconvenience.

Therefore, an object of the present invention is to provide a grain dryer that reduces the combustion amount of the burner in response to the drying air volume reduction operation and prevents the drying air temperature from deviating out of the set range due to the generation of abnormally high-temperature drying air. To realize a dry air temperature control device.

Embodiments of the present invention will be specifically described below based on the drawings.

In FIGS. 1 and 2, a grain dryer 1 has a storage section 2, a drying section 3, and a grain collection section 4, and lifts grains put into a hopper 6 of a grain lifting machine 5, and upper conveying means 7. The grains are conveyed to the upper central part of the dryer 1, dropped evenly into the storage section 2, guided through the drying section 3 to the grain collecting section 4, and transported to the lower part of the grain lifting machine 5 by the lower conveying means 8. The grain is then lifted again by the grain lifting machine 5, and the cycle is repeated to dry the grain.

The drying section 3 has a hot air generator 9 on the front side and an exhaust fan 10 on the rear side.

The exhaust fan 10 is provided with an exhaust fan motor 48, which will be described later, the grain lifting machine 5 is provided with a conveyance motor 49, and the grain collecting section 4 is provided with a circulation motor 51, respectively.

The exhaust fan motor 48 is for driving an exhaust fan, and the exhaust fan motor 48 uses a motor that can change the number of poles, and can be switched between 4 poles and 8 poles (or 4 poles and 6 poles). Can be done.

Further, the rotation speed of the secondary air fan motor 47 is variable by changing the voltage.

The conveyance motor 49 is for driving the grain lifting machine 5 and the upper conveyance means 7.

The circulation motor 51 is a geared motor (electric motor with gears), and is configured so that the circulation speed can be changed by on/off control, and drives the feeding valve and the lower conveying means 8.

Further, 22 is a moisture meter that automatically measures the moisture content of grains.

The hot air generator 9 includes an evaporative oil burner 12 in a casing 9a of the hot air generator, as shown in an enlarged sectional view in FIG.
A combustion cylinder 13 is installed horizontally above the burner.

In addition, 14 is a primary air fan such as a sirocco fan, and 47
1 is a motor for driving the fan, and 16 is an oil pan for collecting waste oil and overflow oil.

A pump 46 is used to feed oil from the oil tank 18 to the burner 12. It uses a reciprocating pump such as a plunger pump and is configured to be driven by an electromagnetic drive device.

A hot air temperature sensor 21 is a hot air temperature sensor made of a thermoelectric conversion element such as a thermistor, and outputs a hot air temperature signal to a temperature control circuit 19a, which will be described later.

Next, the principle of the control circuit 19 will be explained using the block diagram shown in FIG.

In the figure, 20 is an outside air temperature sensor, and 21 is a hot air temperature sensor, which is a hot air temperature sensor.

22 is a moisture meter that samples the drying grain at predetermined intervals and automatically detects the moisture value.

Reference numeral 23 denotes a stop moisture value setting switch, which is used to set a target moisture value of the grain at which drying should be terminated.

24 is a grain amount setting switch for setting the loading amount, 25 is an operation switch, and 26 is a stop switch, which is mainly used for emergency stop.

28 is a group of various safety switches, such as a fire extinguisher activation switch, a grain lifting machine safety switch, and a fuel overflow switch.

29 is a clock oscillator, which generates a synchronizing signal in order to synchronize the operation of each part; 30 is an A/D conversion circuit, which converts analog information signals from the temperature sensors 20, 21, moisture meter, etc. into digital signals; The converting circuit 31 is an encoder that encodes the set values from the stop moisture value setting switch 23 and the grain setting switch 24 and outputs the encoded values to an input data buffer 34 to be described later.

Reference numeral 32 denotes a timer interrupt control circuit, which includes a timer circuit whose time can be set according to instructions from an arithmetic processing unit (hereinafter referred to as CPU) 35, which will be described later, and a circuit which issues an interrupt command to the CPU 35 to indicate completion of the timer operation.

33 is an interrupt control circuit, which controls the A/
A circuit that issues an A/D conversion start command to the D conversion circuit 30;
/D conversion processing completion circuit for issuing an interrupt command to the CPU 35.

34 is an input data buffer, and the A/D conversion circuit 30,
It has a register function for temporarily storing data from the encoder 31, various switches 25, 26, 28, etc. according to instructions from the CPU 35, and then outputting the data to an input data bus 53, which will be described later.

35 is a processing unit (CPU), which is a device that performs storage, calculation, and control functions.

A display control circuit 36 includes a decoder that decodes output data sent from the CPU 35 via an output data bus 55, which will be described later, and a driver that operates an OK monitor display 40, which will be described later.

Reference numeral 37 denotes an output data buffer, which has a register function to temporarily store output data sent from the CPU 35 via an output data bus 55 (described later) in response to a command sent from the same CPU 35 via a control signal line 54 (described later). have

38 is read-only memory (fixed storage device, ROM)
), the CPU 35 operates according to a program stored in the ROM 38 in advance.

39 is a random access memory (constant speed storage device, RAM), which is a readable and writable memory that temporarily stores the calculation results of the CPU 35 and input data.

Each of the above-mentioned devices shown surrounded by a dashed line in FIG.
It is configured as a control microcomputer centered around the CPU 35.

A control microcomputer centered around this CPU 35 operates a calculation section that calculates a decreased oil supply amount value that is proportionally decreased in accordance with a decreased air volume value during low air volume drying by the air volume switching section of the present invention, which will be described later. A control unit is configured to control the amount of oil fed by the pump 46 to be reduced based on the amount value.

The OK monitor display 40 displays the safety status of the dryer.

41 is a numerical display which digitally displays the moisture content of the grain measured by the moisture meter 22 and the hot air temperature alternately.

42 is a burner drive circuit, and 43 is a motor drive circuit, which drive the respective loads according to data from the output data buffer 37.

That is, the burner drive circuit 42 controls and drives the ignition heater 44, the ignition valve 45, the pump 46, and the burner fan motor 47.

The motor drive circuit 43 also includes an exhaust fan motor 48 (in this embodiment, the air volume can be switched in two stages), a conveyance motor 49,
The dust extractor motor 50, circulation motor 51, and moisture meter motor 52 are controlled and driven.

This motor drive circuit 43 and an exhaust fan motor 48 that can switch the air volume in two stages constitute an air volume switching section.

The pump 46 has a structure in which a reciprocating pump such as a plunger pump is driven by electromagnetic driving means, and as described later, the plunger of the pump is driven in response to a pulse signal, and the plunger is moved in proportion to the width of the pulse signal. The method is to change the stroke and control the amount of oil fed.

However, it is also possible to use a system in which the drive cycle of the plunger is changed by changing the frequency of the pulse signal to control the amount of oil fed.

FIG. 5 shows the operation of the control device more specifically using a flowchart.

First, when the operation switch 25 shown in Fig. 4 is turned on, the RO
The M38 program starts and the drying starts 1 in Figure 5.
00, and the various motors 48 to 52 start operating.

Next, according to the program in the ROM 38, the burner drive circuit 42 shown in FIG. The motor 47 is driven to enter the burner ignition state 101 shown in FIG.

102 compares the grain moisture value obtained from the moisture meter 22 in FIG. 4 with the set value of the stop moisture value setting switch 23, and if the moisture value does not reach the set value, the process proceeds to 103, and the moisture value is determined to be the set value. When reaching , the process proceeds to 117.

At 117, the burner is extinguished, and the burner drive circuit 42 performs a series of operations to extinguish the burner 12, and at 118
The various motors are stopped at , and the drying end state 119 is reached.

103 is an input of hot air temperature Tb, which is a routine that proceeds when the moisture value is less than a set value, and the hot air temperature Tb is input from the hot air temperature sensor 21.

Next, calculation of the set temperature Tc at 104 is performed based on the signals from the outside air temperature sensor 20, the moisture meter 22, and the grain amount setting switch 24, and the set temperature Tc is determined.

In step 105, a determination is made as to whether the moisture value of the grain is 16% or less.

If YES, that is, the moisture value is 16% or less, proceed to 12°C, set the drying air volume reduction flag FR,
At step 121, a reduced oil supply amount value is calculated according to the reduced airflow amount value, and the pump drive pulse width is set to TwX(A2/AI).

In other words, the amount of oil sent is reduced in proportion to the amount of air.

Note that A1 indicates a large air volume, which will be described later, and A2 indicates a small air volume.

Then, return to the original main routine. If the judgment in step 105 is NO, proceed directly to □ 106 and select lTc-
It is determined that Tb1≦1.

Then, if the value is 1 or more, that is, the temperature difference is 1°C or more, the process branches to 122, and if it is less than 1°C, the process proceeds to 107, and the pulse width is the same as that determined in the previous routine;
Oil is pumped for rw.

The routine starting from 122 increases the oil supply amount (123)
Or it is a program to decrease (124).

At step 122, it is determined whether T c −T b >O, and if the answer is yes, the process branches to 123, and if the answer is no, the process branches to 124.

That is, if the hot air temperature Tb is too high than the set temperature Tc, the amount of oil fed is decreased, and if the hot air temperature Tb is too low, the amount of oil fed is increased.

That is, if Tb is too high, Tb at 124
Determine c+4≧Tb≧Tc+1.

If Tb is more than 1°C and less than 4°C than Tc, the process proceeds to 127 and the pump drive pulse width Tw is changed to Δτ(Δτ
τ: minimum variable pulse width), the stroke of the pump 46 is proportionally reduced by the pulse width, and the amount of oil fed is reduced.

Furthermore, if T b > T c + 4, 128
Then, the pump drive pulse width Tw is decreased by 2Δτ, and the amount of oil fed is drastically reduced.

And again, if Tb is too low, proceed to 123 and Tb
c-1> T b ≧ T c -4, and if yes, proceed to 126 and set the pump drive pulse width Tw to Δ
Increase by τ.

If the answer is NO, go to 125 and set the pulse width Tw to 2.
Increase by Δτ.

In other words, the degree of correction for increasing or decreasing the amount of oil fed is changed depending on the extent of the difference from the set value.

Then, return to the original main routine.

Then, at 108, the pump 46 shown in FIG. 4 is controlled, and at 109
The burner fan motor 47 is controlled at step 110, and the circulation motor 51 is turned on and off at step 110.

Then, in step 111, it is checked whether the drying air volume reduction flag FR in step 120 is set.

If the answer is YES, as shown in FIG. 6, in step 114, the motor drive circuit 43 lowers the speed of the exhaust fan motor 48 to reduce the air volume to a small air volume A2.

Then, in step 115, the air volume of the primary air fan motor 47 is set to a small air volume A2 as shown in FIG. 6, and is conversely increased from the air volume A1 at the time of the large air volume.

This is taken as a means to compensate for the decrease in the amount of primary air to the burner due to the deceleration of the exhaust fan motor 48.

Further, if the determination at 111 is NO, the process proceeds to 112, where the exhaust fan motor 48 is maintained at the large air volume A1, and at 113, the primary air fan motor 47 is maintained at the air volume A1.

Next, in step 116, it is checked whether or not the hot air temperature sampling timer Ts has timed out, and if yes, the routine jumps to step 108 and the routine starting from step 108 is repeated.

And if it's yes, it jumps to 102, 102
Proceed through the routine previously described starting with .

In this way, when the drying air volume is reduced by the air volume switching section during drying to perform small air volume drying, the present invention calculates an oil supply volume value that is proportionally reduced in accordance with the decreased air volume value, and adjusts the oil supply volume accordingly. The pump 46 is driven and controlled based on the value.

Since the control device is configured as described above, it operates as follows.

When the grain moisture value reaches 16%, the drying air volume A1 is approximately halved to the drying air volume A2, as shown in FIG. 6, in order to perform small air volume drying.

At this time, according to the conventional control device, the pump oil supply amount V1 gradually decreases as shown in the graph py qt r of the oil supply amount v1 in FIG. There is a disadvantage that a mountain-shaped temperature curve showing a sudden rise is drawn.

However, in the present invention, as described above, the oil supply amount is instantly reduced to V2=VI
Although the temperature decreases to a point S within the set temperature Tc (shaded area) in the figure, the set temperature Tc is maintained.
An ideal drying air temperature Tb can be achieved.

In addition, in the above embodiment, the oil supply amount is controlled to increase or decrease by widening or narrowing the pulse width Tw, but it is also possible to adopt a configuration in which the oil supply amount is controlled to increase or decrease by changing the frequency of the pulse. .

As is clear from the above embodiments, according to the present invention, the following effects can be obtained.

(1) As the drying air volume is controlled to decrease when the grain moisture value reaches a predetermined moisture value, the control device is configured to instantaneously reduce the oil supply amount in proportion to the decrease in air volume. There is no inconvenience of raising the drying air temperature beyond the set temperature range, there is no needless anxiety for dryer users, there is no need to expose the grain to undesirable hot air, and smooth operation control ensures high quality. You can get dry grains.

(2) Also, the entire control circuit can be configured without using mechanical cams, contacts, etc. If configured in this way, it can be integrated into an integrated circuit if necessary, making it compact and highly reliable. A control device can be realized.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional side view of the dryer, FIG. 2 is a cross-sectional view taken along line [-11 of FIG. 1, and FIG. 3 is a system diagram showing the control system. , Fig. 4 is a block diagram of the control device, Fig. 5 is a flowchart explaining the operation of the control device, and Fig. 6 shows the primary air fan air volume A, the pump oil supply volume V, the drying air temperature Tb, and the drying air volume A. It is a graph showing each correspondence relationship. (Explanation of main symbols), 1 is a grain dryer, 12 is a burner, 19 is a control circuit, 35 is a processing unit (CPU), 3
8 is read-only memory (fixed storage device, ROM)
, 39 is a random access memory (constant speed storage device, RAM), and 46 is a pump.

Claims (1)

[Claims] 1 In a drying air temperature control device for a grain dryer that increases or decreases the amount of oil fed depending on the difference between the drying air setting temperature and the drying air detection temperature, an air volume switching unit that reduces the drying air volume and switches to a small air volume during drying. , a calculation unit that calculates a reduced oil supply amount value that is reduced approximately proportionally in accordance with the reduced air volume value during drying with a small air volume, and a control unit that controls the oil delivery amount to be reduced based on this reduced oil supply amount value. A drying air temperature control device for a grain dryer, characterized in that: