KR100646334B1 - Apparatus for sencing the water level - Google Patents

Abstract

The present invention relates to a water level detection device of a hot water heating system, and more particularly to a device that can detect the water level without a separate signal output for the water level detection.

According to an embodiment of the present invention, there is provided a water level detecting device comprising: a square wave pulse generator for generating a square wave pulse by rectifying half-wave rectified AC input power; A level detector for level converting each of the square wave pulses input through different paths according to whether each of the probe rods is electrically grounded and outputting a high level and low level detection signal; And a controller configured to control the operation of the hot water heating mechanism according to the presence or absence of a pulse input of the high water level and low water level detection signals inputted from the water level detection unit.

High water level, index finger, meter reading rod.

Description

Apparatus for sencing the water level}

1 is a circuit diagram of a water level detecting device according to an embodiment of the present invention.

2A to 2D are timing charts for explaining the operation of the water level detecting device according to the embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

10: square wave pulse generator 20: water level detector

30: micom 40: meter reading rod

50: water tank

The present invention relates to a water level detection device of a hot water heating system, and more particularly to a device that can detect the water level without a separate signal output for the water level detection.

In the hot water heating system, the water level in the water tank must be detected first for safe system operation. As a device for detecting the water level, various devices such as a device using a probe rod, a device using a float, a device using a pressure-sensitive water level sensor, and the like have been widely introduced.

Among them, a device for detecting the water level by using a metering rod (also called an electrode rod) will be described in detail.

First, the metering rods with different heights are installed in the water tank. These reading rods are installed to detect a high level and a low level, respectively, and are vertically spaced apart from the bottom of the water tank by a predetermined distance. If the water tank is grounded or if a separate earthing probe is installed on the bottom of the water tank, the water tank (or the earthing probe) and the high or low level probe will be contacted by water.

If the microcomputer outputs a predetermined level of control signal to each of the high level probe and the low level probe, the control signal is grounded according to the water level. Therefore, the microcomputer can detect the high and low water conditions by monitoring the voltage drop of each of the reading rods while outputting the control signal of the predetermined level.

However, in the general level detection device as described above, since the microcomputer outputs a separate control signal for detecting the level and receives a feedback signal through a separate port, an input / output pin for detecting the level is excessively used.

In addition, if a failure occurs in the output pin of the control signal output or the output path of the control signal, even if the metering rod and the water tank is contacted via water, the level of the control signal applied to the metering rod is not grounded to the microcomputer The level of the feedback signal is also unchanged, leaving the high level undetectable.

In addition, in the above-described water level detection device, a control signal is continuously applied to the probe bar. As a result, when the control signal is continuously applied to the probe bar, the probe rod is oxidized by the applied current. You get

Accordingly, an object of the present invention is to provide a water level detection device that detects the water level using a metering rod, and can detect the water level in the water tank without outputting a separate control signal for detecting the water level.

Furthermore, it is to provide a level detection device that can increase the pin utilization of the microcomputer by minimizing the number of pins required for the level detection.

Still another object of the present invention is to provide a water level detection device which can prevent oxidation of the probe rod and extend its life.

The water level detecting device according to an embodiment of the present invention for achieving the above object, as a device for detecting the water level through the probe rods which are located at different heights in the water tank and electrically grounded by the stored water,

A square wave pulse generator for generating a square wave pulse by rectifying the AC input power half-wave and outputting the same through a different path;

A level detector for level converting each of the square wave pulses input through different paths according to whether the probe is electrically grounded and outputting the signal as a high level and a low level detection signal;

And a controller for controlling the driving of the hot water heating mechanism according to the presence or absence of a pulse input of the high water level and low water level detection signals inputted from the water level detection unit.

Furthermore, the water level detecting unit;

Transistors connected to each of the base terminals and outputting the square wave pulses input to the emitter stage to the collector stage when each of the connected probe rods is electrically grounded;

And inverters for inverting the output levels of the transistors and outputting the high level and low level detection signals.

The control unit outputs a system failure state when a pulse of the high level detection signal is input without a pulse input of the low level detection signal.

According to the characteristics of the present invention as described above, the controller can detect the water level in the water tank through the two input pins without outputting a separate control signal for detecting the water level, thereby improving the pin utilization of the microcomputer as a control unit. You will be able to.

In addition, since the square wave pulse is periodically generated and applied for detecting the water level, it is possible to obtain the effect of extending the life of the reading rods compared to general devices which continuously apply the control signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

First, FIG. 1 shows a circuit diagram of a water level detection device according to an embodiment of the present invention, and FIGS. 2A to 2D show timing diagrams for explaining the operation of the water level detection device according to an embodiment of the present invention. will be.

As shown in FIG. 1, the water level detection device according to the embodiment of the present invention includes a square wave pulse generator 10, a water level detector 20, and a controller 30.

The square wave pulse generator 10 generates a square wave pulse by half-wave rectifying the AC input power source AC 18V and outputs the square wave pulse through different paths. To this end, the square wave pulse generator 10 includes diodes D1 and D2 for half-wave rectifying the AC input power AC, and NPN-type transistors TR1 for inputting the half-wave rectified waveform to generate square wave pulses. TR2). For reference, the "different paths" are paths for transmitting square wave pulses for detecting high and low water levels.

2A shows a waveform that is half-wave rectified by the square wave pulse generator 10 and a corresponding square wave pulse. In FIG. 2A, the generation period of the square wave pulse is 8.34 ms when the frequency of the AC input power source is 60 Hz, and 10 ms when 50 Hz.

In conclusion, the square wave pulse generator 10 generates a square wave pulse as shown in FIG. 2A and is applied to the PNP type transistor in the water level detector 20 to be described later through different paths.

On the other hand, the water level detector 20 is located at different heights in the water tank 50, and different paths depending on whether or not the electrical grounding of the probe rods 40 that are electrically grounded by water contained in the water tank 50. Level converting each of the square wave pulses input through the high-level and low-level detection signal is output.

The water level detecting unit 20 has transistors for outputting the square wave pulses input to the emitter stage when the probe rods 40 are connected to each of the base terminals, and each of the connected probe rods 40 is electrically grounded. TR3 and TR4 and inverters INV1 and INV2 that invert the output levels of the transistors TR3 and TR4 and output the high level and low level detection signals.

That is, the square wave pulses input to the emitter stages of the transistors TR3 and TR4 in the water level detector 20 are inverters through the collector stages of the corresponding transistors TR3 and TR4 depending on whether the high level (HI) reading rod and the low level reading rod are grounded. As applied to the fields INV1 and INV2, each inverter outputs a square wave pulse having a "low" level when the probe rod 40 is grounded. Examples of output waveforms of the inverters INV1 and INV2 are illustrated in FIGS. 2B, 2C, and 2D.

2B illustrates a low level detection signal and a high level detection signal output from the inverters INV1 and INV2 when only the low level reading rod is grounded by water, and only the low level detection signal is output in the form of a square wave pulse to be described later. Is input to the microcomputer 30.

FIG. 2C illustrates a case in which both the low level probe and the high level probe are grounded by water, and each of the low level detection signal and the high level detection signal output from the inverters INV1 and INV2 are output in the form of a square wave pulse.

On the other hand, Figure 2d shows a case where only the high water level reading rod is grounded by water, and such a situation cannot occur, so the microcomputer 30 to be described later receives the low water level detection signal and the high water level detection signal as shown in FIG. In this case, it judges the logic error status and outputs the system failure status (alarm type).

Finally, the microcomputer 30 as a control unit controls the driving of the hot water heating mechanism according to the presence or absence of pulse input of the high and low water level detection signals input from the water level detecting unit 20. As mentioned above, the microcomputer 30 outputs a system failure state when a square wave pulse of the high level detection signal is input without a pulse input of the low level detection signal.

Hereinafter, the operation of the water level detecting device according to the embodiment of the present invention will be briefly described with reference to FIG. 1. First, the square wave pulse generator 10 generates a square wave pulse periodically according to the frequency of an AC input power source. Is applied to the transistors TR3 and TR4 of the PNP type.

If the low level probe rod and the high level probe rod are grounded through water, respectively, the transistors TR3 and TR4 are switched on so that the square wave pulses are applied to the inverters INV1 and INV2. Accordingly, the inverters INV1 and INV2 invert and output the level of the applied square wave pulse, so that the low level square wave pulse is input to the microcomputer 30.

Therefore, the microcomputer 30 can determine whether the current water tank is at a low water level, a high water level, or a system failure state as the high water level detection signal and the low water level detection signal are input in the form of a square wave pulse.

As described above, the present invention can detect the water level in the water tank using only the water level detection signal input through the two input pins without outputting a separate control signal for detecting the water level, thereby reducing the load of the microcomputer as a control unit. In addition to this, there is an advantage that can improve pin utilization.

In addition, since the present invention periodically generates and applies a square wave pulse for detecting the water level, it is also possible to obtain an effect of extending the life of the probe rod compared to general devices that continuously apply the control signal.

On the other hand, the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be defined only by the appended claims.

Claims (3)

delete In the device for detecting the water level through the reading rods which are located at different heights in the water tank and electrically grounded by the stored water, A square wave pulse generator for generating a square wave pulse by rectifying the AC input power half-wave and outputting the same through a different path; Level-convert each of the square wave pulses input through different paths according to whether the probe rods are electrically grounded, and output them as high and low water level detection signals, with the probe rods connected to each of the base ends, and each of the probe rods electrically connected. A level detector comprising transistors for outputting the square wave pulses input to the emitter stage to the collector stage when grounded, and inverters for inverting the output levels of the transistors and outputting them as high and low level detection signals; And a control unit for controlling the driving of the hot water heating mechanism according to the presence or absence of a pulse input of the high water level and low water level detection signals inputted from the water level detection unit. The water level detecting apparatus according to claim 2, wherein the controller outputs a system failure state when a pulse of the high level detection signal is input without a pulse input of the low level detection signal.

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