JPH0112110Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an automatic ventilation system for agricultural or horticultural greenhouses that reliably closes the ventilation windows during rain to prevent damage to plants in the greenhouse due to invasion of bacteria, excessive humidity, flooding, etc. caused by rainwater. This relates to a device for

In general, greenhouses are ventilated appropriately using ceiling ventilation windows or ventilation fans to regulate the indoor temperature so that the indoor temperature does not rise too much due to solar heat.

FIG. 1 schematically shows the state of such a greenhouse. A ventilation window 2 installed in the ceiling of the greenhouse 1 is controlled by a control device 4 that receives the output of a thermostat 3 that detects the indoor temperature. Driven electric motor 5
The ventilation windows are controlled to open and close when the temperature is high and to open when the temperature is low.

In a greenhouse equipped with an automatic ventilation system that operates in this way, the infiltration of raindrops during rain can lead to the introduction of pathogenic bacteria, overhumidification, and direct damage to crops, so when it rains, it should be removed as quickly as possible regardless of the indoor temperature. It is necessary to close ventilation windows. Normally, a supervisor detects rain and switches the controls to manual operation, closing the ventilation windows. However, if there are multiple greenhouses, the time required to close the greenhouse will be longer, making it impossible to close the greenhouse in time when sudden rainfall starts, such as during summer showers. Furthermore, if the supervisor is away due to going out, etc., the system is completely defenseless, which can sometimes lead to serious damage.

Therefore, an unmanned device that automatically detects rainfall and automatically closes ventilation windows is needed.
Although various proposals have been made, none of them are reliable rain detectors, and for this reason, automatic opening/closing devices have hardly been put into practical use.

Conventionally, as a device for automatically detecting rainfall for use in such unmanned equipment, there is an acoustic type that receives raindrops falling on a sounding board and receives the sound with a microphone to generate an output. There are also devices that use a hygrometer to detect sudden changes in humidity, and devices that detect changes in resistance between two parallel electrodes by short-circuiting them with rainwater. Proposed. However, the above-described first method is susceptible to external noise, and malfunctions cannot be completely prevented even if a soundproofing device is provided. In addition, the second method has many problems with the moisture detector itself, and even when it is not actually raining, the humidity in the air is abnormally high, such as just before the start of rain or after the rain. The disadvantage is that it generates an output of Furthermore, the third method is unrelated to external noise and atmospheric humidity, but even after rain stops, raindrops remain between the electrodes due to surface tension or capillary action, and the signal continues to be output even when it is still raining. Sometimes it happens. Therefore, as a method to prevent this, special measures have been required such as installing a powerful heater near the electrodes to evaporate residual rainwater between the electrodes in a short period of time.

The present invention is a rain detection device that obtains a signal to automatically close ventilation windows when it rains, and improves the electrode structure of the third electrode type detection device mentioned above. This paper proposes an automatic ventilation system for greenhouses using a new rainfall detection device that has a simple structure without using any means, can detect rain immediately from the onset of rain, and can detect the cessation of rain without delay when it stops raining. .

FIG. 2 is a sectional view of the main body of the detector used in the automatic ventilation system of the present invention. In the figure, reference numeral 11 denotes a funnel-shaped body for collecting raindrops, which is installed outdoors so that its upper opening surface is substantially horizontal. 12 is a funnel-shaped body 11
It is a drainage part provided at the bottom of the rainwater drain for guiding the collected water to the outside, and is designed to allow the collected rainwater to flow downward without resistance. Reference numeral 13 denotes a rod-shaped or wire-shaped first electrode attached to the inside of the lead-out part 12, and its diameter is such that there is a slight gap between it and the inner wall of the lead-out part 12, and it penetrates the inside of the lead-out part 12. The tip thereof is located at a position protruding outward from the lower end of the lead-out portion 12. 14 is a second electrode that faces the first electrode 13 and maintains a gap therebetween, and is fixed in an electrically insulated state from the first electrode 13 by an insulator 15, for example, as shown in the figure. In this way, a rod-shaped or wire-shaped electrode similar to the first electrode 13 is used, which is once lowered down and then turned upside down. 16
17 is a detection circuit that detects the impedance change between the electrode 13 and the electrode 14, and 17 is the detection circuit 1.
6, a time limit circuit that operates for a certain period of time in response to the impedance lowering output signal; 18, a motor control circuit that operates the motor 5 in forward and reverse directions to open and close the window according to the output of the thermostat 3 shown in FIG. 1 and manual commands; 19
is the thermostat 3 during the operation time of the timer circuit 17.
This is a forced closing circuit for operating the electric motor 5 in the direction in which the window 2 is closed, giving priority to other control signals such as manual commands. In the embodiment shown in the figure,
When raindrops are captured by the funnel-shaped body 11, the raindrops travel along the wall surface of the funnel-shaped body 11 due to gravity and reach the outlet part 12, but the surface tension is reduced by the first electrode 13, so that even if the raindrops are small, Even if it does, it does not remain in the lead-out portion 12 and immediately falls along the first electrode 13. These raindrops drop onto the first electrode 13 while falling.
The lower end of the electrode and the second electrode 14 are bridged. At this time, the impedance between the first electrode 13 and the second electrode 14 changes suddenly, so if this is detected by the detection circuit 16, it can be detected even in the very early stages of rain. Furthermore, since the rainwater is accelerated while falling along the first electrode 13, its speed is sufficiently high when it reaches the second electrode 14.
The first electrode 13 and the second electrode 14 do not remain in a bridged state, and there is no possibility that the detection signal will continue to be output even when rain stops, unlike the conventional device.

The output of the detection circuit 16 is supplied to a time limit circuit 17, and the time limit circuit 17 outputs the output for a certain period of time from when the raindrop bridges between the electrodes 13 and 14, or when the raindrop bridges between the electrodes 13 and 14. The output is output immediately after the bridge has disappeared, and the output is continuously supplied to the forced closing circuit 19 for a certain period of time even after the bridge has disappeared. Generates a command to drive.

Various circuits can be considered for detecting changes in impedance between electrodes due to rainwater, but a circuit that detects changes in direct current resistance between electrodes is usually sufficient.

FIG. 3 is a connection diagram showing a specific embodiment of the detection circuit 16, time limit circuit 17, motor control circuit 18, and forced closing circuit 19. In the same figure, a detection circuit 16 includes resistors R1 to R4, transistors Tr1 and Tr2, and a relay CR1. The circuit shown in the figure includes resistors R1 to R4 connected to a power source E1, which is a rectified AC power source e, and a transistor Tr1.
It leads to the base circuit of the amplifier consisting of Tr2 and Tr2, and operates the output relay CR1,
When rainwater bridges between electrode 13 and electrode 14, electrode 13 and electrode 1, which had previously had high resistance,
The resistance value (hereinafter referred to as r34) between 4 and 4 is several 100
The value is as low as ohms. For this reason, a base current flows through the transistor Tr1, making it conductive, which makes both the transistor Tr1 and the Darlington-connected transistor Tr2 conductive, energizing the relay CR1, closing the output contact CR1a, and making the relay CR1 self-holding. Ru. The time limit circuit 17 is a timer TDR of time limit operation and instant return type, and its normally closed contact TDRb interrupts the self-holding circuit of the relay CR1 when the time limit is completed. Motor control circuit 1
8 is an automatic-manual changeover switch S1, a manual command switch S2 that opens and closes the window when it is in manual mode, a thermostat 3 whose H contact closes when the room temperature rises and whose L contact closes when it falls, a limit switch LS1 which opens at the window's opening limit; It consists of a limit switch LS2 that opens when the window is closed, and relays CR2 and CR3. When there is no rain, the contacts of relay CR1
Since CR1b is closed, relay CR2 or CR3 is energized by the H or L contact of the thermostat or a manual opening/closing command, and contact CR2
A or CR3a rotates the electric motor 5 forward or reverse to open or close the window.
Drive until LS1 or LS2 operates.

When the rain starts and the relay CR1 of the detection circuit is energized, the contact CR1b of the forced closing circuit 19 opens.
Since contact CR1a closes, the automatic and manual command circuits are cut off, and only the circuit of window closing relay CR3 is enabled, and during the time period set by timer TDR, motor 5 is directed to close the window with priority over other command signals. Rotate. When the normally closed contact TDRb opens due to the expiration of the timer TDR, the self-holding state of the relay CR1 is released. If rainwater exists between electrode 13 and electrode 14 at that time, relay CR
1 continues to be energized, but if there is no rainwater, transistors Tr1 and Tr2 are in a cut-off state, so relay CR1 is also de-energized, and contact CR1a is opened. Therefore, the electrodes 13 and 14 are damaged by rainwater.
The period from immediately after the bridge is bridged until the set time of the timer TDR is completed, that is, the set time of the timer TDR becomes the sampling period and the hold time.
By providing a timer circuit in this way, smooth closing can be achieved without the motor turning on and off repeatedly even when raindrops arrive intermittently. If this time is set to about a fraction of the time required for a fully open ventilation window to completely close, the closing operation will be performed while checking the rain situation during closing, and a very small amount of rain will be removed. It is best to use it every time, so that it does not close completely even when it rains. In addition, in FIG. 3, raindrops are connected to electrode 13 and electrode 1.
Relay CR for a certain period of time immediately after bridging with 4
In order to stably detect intermittent raindrops, a delay return time element may be provided to continue energizing relay CR1 for a certain period of time even after the bridging of raindrops is resolved. For this purpose, a further delayed return timer may be provided, but the relay
A capacitor may be connected in parallel to the coil of CR1 to delay the return of relay CR1 by the discharge current of the capacitor.

FIGS. 4a and 4b show other embodiments of the detection circuit, in which only the main parts are shown. Fourth
In figure a, E2 is a power supply, R7 is a resistor, ZD is a constant voltage diode, MM1 is a mono multivibrator that outputs a pulse with a fixed time width at the falling edge of the input signal, and VR1 and C1 are connected to mono multivibrator MM1. Variable resistor and capacitor to determine the output pulse width, A1 amplifies the output of mono multivibrator MM1 and connects relay CR
This is an amplifier for operating 1. In the embodiment shown in the figure, when there are no raindrops, the electrode 13 and the electrode 14
Since the resistance value r34 between the two is high, the terminal voltage thereof is high, the constant voltage diode ZD is conductive, and the input of the mono multivibrator MM1 is at a high level (H level). When raindrops bridge between the electrodes 13 and 14, the resistance value r34 decreases, and the resistance value of the resistor R7 is determined so that the terminal voltage at this time is lower than the Zener voltage of the constant voltage diode ZD. Each time a raindrop bridges electrodes 13 and 14, mono multivibrator MM1 outputs a pulse with a fixed time width to amplifier A1, and during this time the relay
CR1 is energized, and the same operation as relay CR1 in FIG. 3 is obtained.

FIG. 4b is a connection diagram showing yet another embodiment of the detection circuit. In the figure, reference numerals 31 and 41 are mock electrodes made using electrodes and insulators made of the same material so as to be in approximately the same state as the detector main body 11, and the insulation deteriorates mainly due to aging of the insulator 15. The detector main body 1 is tuned to the change in resistance value r34 between the electrode 13 and the electrode 14 caused by
1 or near it, R5, R6
is a resistor that is connected to the power source E3 together with the electrodes 13, 14, 31, and 41 to form a bridge circuit. In addition, 21 is a relay CR1 when the output voltage of this bridge circuit is reversed.
This is an amplifier circuit that excites the . In the figure, the resistance values of resistors R5 and R6 are set as r5 and r6, and the electrode 31
When the resistance value between and the electrode 41 is r34',
As mentioned above, r34 and r34' are approximately equal when there is no rainwater. Therefore, the resistance value r5 is the resistance value r
resistor R so that it has a value slightly greater than 6
If 5 and R6 are selected, rainwater will flow to the electrode 13.
Until the terminal A and the electrode 14 are bridged, the terminal A side in the figure is slightly lower than the B side. In such a state, if a raindrop bridges the gap between electrode 13 and electrode 14, the resistance value r34 decreases significantly compared to the resistance value r34', so that the voltage between terminals A and B is reversed and the voltage between terminals B and B is reversed. The side is clearly reversed so that it is lower than the terminal A side. Therefore, if the polarity reversal of the voltage between the terminals A and B is detected by the amplifier circuit 21, accurate detection is always possible regardless of the resistance value itself of the resistance value r34.

Note that the shape of the electrodes 14 of the detector body is not limited to that shown in FIG. 2, and rainwater collected by the funnel-shaped body 11 and led down by the electrodes 13 may accumulate between the electrodes. It suffices if it has a structure that allows it to flow away quickly.

FIGS. 5a to 5c show another embodiment of the second electrode 14, in which A shows a side view and B shows a plan view, respectively. Figures a and b show the second electrode 14 with its side facing the first electrode 13, and both are sloped so that rainwater can quickly flow away. . Also, the same figure c
The second electrode 14 is not rod-shaped but flat plate-shaped, with its surface facing the tip of the first electrode 13 and inclined to prevent rainwater from accumulating.

As mentioned above, in the ventilation system of the present invention,
A funnel-shaped body captures and collects raindrops over a relatively wide area, and a rod-shaped or wire-shaped electrode reduces the surface tension and allows them to flow down quickly, and a second electrode is placed opposite to this electrode. A raindrop detector is used to detect impedance changes caused by rainwater bridging between these two electrodes, and a time-limited circuit is prepared that generates an output for a certain period of time based on this detection signal. Since the system has a structure that forcibly closes the ventilation windows with priority over command signals, it is possible to extremely accurately detect the start and end of rain and automatically prevent rainwater from entering, allowing unattended management of the greenhouse. becomes.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining a general ventilation system for greenhouses, which is the subject of the present invention, Figure 2 is a sectional view showing the structure of the detector body used in the automatic ventilation system of the present invention, and Figure 3 is A detection circuit 16, a time limit circuit 17, a motor control circuit 18, used in the automatic ventilation system of the present invention,
A connection diagram showing a specific embodiment of the forced closure circuit 19, FIGS. 4a and 4b are connection diagrams showing another embodiment of the detection circuit, and FIGS. It is a figure showing an example of
In each figure, A shows a side view, and B shows a plan view. 1... Greenhouse, 2... Ventilation window, 5... Electric motor, 1
1... funnel-shaped body, 12... derivation part, 13... first
electrode, 14... second electrode, 15... insulator,
16...Detection circuit, 17...Time limit circuit, 18...
Motor control circuit, 19...forced closing circuit.

Claims (1)

[Scope of utility model registration request] An automatic ventilation system for a greenhouse having a ventilation window that opens and closes according to the indoor temperature or a manual command, comprising: a funnel-shaped raindrop collector having an opening at the top; a collected water outlet provided at the bottom of the raindrop collector; a first rod-shaped electrode penetrating the inside of the lead-out portion and hanging down;
a second electrode provided opposite to the first rod-shaped electrode with a predetermined gap therebetween and insulated from the first rod-shaped electrode; and an impedance change between the first electrode and the second electrode. a detection circuit for detecting the
a time limit circuit that operates according to the impedance drop detection output of the detection circuit; and a time limit circuit that operates according to the impedance drop detection output of the detection circuit; An automatic ventilation system for a greenhouse, which is equipped with means for forcing ventilation windows to close in the closing direction.