JPH043231Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a water pressure detection circuit in an automatic water supply mechanism, and in particular, to a water pressure detection circuit in an automatic water supply mechanism that can prevent malfunctions caused by attenuated waves of the water hammer phenomenon. It is related to circuits.

[Conventional example]

Conventionally, in an automatic water supply mechanism for a bath or the like, as shown in FIG. 2, a solenoid valve 9 is opened to supply water to a hopper 6, and water is dropped from the hopper 6 into a bathtub 8 via a three-way valve 3 by a pump 2, and a predetermined amount of water is supplied to the bathtub 8. When the pressure sensor 1 disposed in one of the circulation paths detects that the water level has reached , the water supply control circuit closes the solenoid valve 9 to stop the water supply. The three-way valve 3 is connected to the bathtub 8
A solenoid valve 7 is further interposed in the circulation path section 5 connected to the lower part of the bathtub 8.
After the pressure sensor 1 side circulation path 5 is filled with water, the hopper water is conveyed through the other circulation path 4. A control circuit that outputs switching commands for both valves 3 and 7 is not shown. FIG. 1 shows a water pressure detection circuit, which consists of a voltage level determination circuit 10 and a hysteresis circuit 11 attached to the circuit 10. The voltage level determination circuit 10 has an output from the pressure sensor 1.
It is composed of a comparison circuit which inputs OP- to the negative phase input terminal and inputs the output of the hysteresis circuit 11 to the positive phase input terminal as a reference voltage. The hysteresis circuit 11 that generates the reference voltage outputs a predetermined high value reference voltage V _REFH as a reference voltage when the output of the pressure sensor 1 increases, and outputs a predetermined high value reference voltage V _REFH as a reference voltage when the output of the pressure sensor 1 decreases. The low voltage reference voltage V _REFL is output as the reference voltage. That is, this reference voltage generation circuit includes a voltage dividing resistor R1, voltage dividing resistors R2 and R3 commonly connected to the voltage dividing resistor R1, a transistor Q1 connected in series with the voltage dividing resistor R3, and Another voltage dividing resistor R4, R5 is connected in series to the output terminal of the circuit 10, the base is connected to the voltage dividing point of the voltage dividing resistor R4, R5, the collector is connected to the base power supply circuit of the transistor Q1, and the emitter is grounded. and a transistor Q2.

In the above configuration, at the start of water supply, the output of the water pressure sensor 1 is 0, and the voltage level determination circuit 10
The output of is high, the reference voltage OP+ is the high value reference voltage V _REFH as shown in Figure 3, and the three-way valve 3
is switched to the c-d connection position where the hopper 6 is connected to the circulation path section 5 side connected to the lower part of the bathtub 8,
Solenoid valve 7 is opened. After the inside of the circulation path 5 is air purged, it is switched to the ca connection position. Eventually, when the water level in the bathtub 8 reaches a predetermined value, the output OP- of the pressure sensor 1 becomes equal to or higher than the high value reference voltage V _REFH , and at this point the output of the voltage level determination circuit 10 is switched to a low value. As a result, on the one hand, the reference voltage OP+ changes to the low reference voltage as shown in Figure 3.
V Switched to _REFL . In order for the pressure sensor 1 to detect the water level in the bathtub 8, the circulation path 5 must be filled with water, so the three-way valve must be closed before detection.
- Switch to b side and perform air purge. When the air purge is completed, the three-way valve 3 is switched to the c-a connection position where the hopper 6 is connected to the circulation path section 4 side connected to the upper part of the bathtub 8, as shown in FIG. 4, and the solenoid valve 7 is switched to the fourth The valve is closed as shown in FIG.

[Problem that the invention attempts to solve]

By the way, when switching the three-way valve 3 and the solenoid valve 7, a water hammer phenomenon occurs as shown in FIG. Voltage
This creates a damped wave that overcomes V _REFH and the low-value reference voltage V _REFL , which may cause the control circuit to malfunction. That is, as shown in FIG. 4, the high reference voltage V _REFH
When it converges after overcoming this, the reference voltage of the comparator circuit 10 becomes V _REFL , and even though the water level has not yet reached V _REFH , the solenoid valve 9 is closed and the water supply is stopped.

The present invention has been developed in consideration of the above-mentioned circumstances, and is intended to be used, for example, in automatic water supply mechanisms for baths, etc., to prevent malfunctions caused by attenuated waves of the water hammer phenomenon that occur when switching between three-way valves and solenoid valves. The purpose is to provide a water pressure detection circuit.

[Means for solving problems]

The water pressure detection circuit in an automatic water supply mechanism for a bath or the like according to the present invention includes a voltage level determination means for determining whether the output of the pressure sensor exceeds a predetermined reference voltage, and a conveyance path from the circulation path having the pressure sensor to the other side. Canceling means is provided for inactivating the input to the voltage level determination circuit for a predetermined period of time from the time when the circuit is switched to the circuit.

〔Example〕

Hereinafter, the present invention will be specifically explained based on illustrated examples.

FIG. 1 is a circuit diagram of a control circuit of an automatic bath water supply mechanism according to the present invention, and FIG. 2 is a configuration diagram of the automatic bath water supply mechanism.

In FIG. 2, 1 is a pressure sensor, 2 is a pump, 3 is a three-way valve, 4 and 5 are circulation path parts, 6 is a hopper, 7 is a solenoid valve, 8 is a bathtub, and 9 is a solenoid valve.
Further, in FIG. 1, 10 is a comparison circuit, 11 is a hysteresis circuit, 12 is a hysteresis cancel circuit, 13 is a cancel signal generation circuit, R1,
R2, R3, R4, R5 are each resistance, Q1, Q2,
Q3 is each transistor.

The comparator circuit 10 has a negative phase input terminal connected to the pressure sensor 1.
The positive phase input terminal is connected to the voltage dividing point of voltage dividing resistors R1 and R2. R3 is a parallel voltage dividing resistor connected in parallel with R2, the first transistor Q1 is connected in series with the parallel voltage dividing resistor R3, and each other voltage dividing resistor is connected in series with the output terminal of the comparison circuit 10. R4, R5, a second transistor Q2 whose base is connected to the voltage dividing point of these voltage dividing resistors, whose collector is connected to the base power supply circuit of the first transistor, and whose emitter is grounded, and the first transistor Q1. The collector is connected to the base power circuit of
a third transistor Q3 whose emitter is grounded;
A cancel signal generating circuit 13 is provided at the base of the third transistor Q3 for applying a gate voltage for a predetermined time T from the time when the three-way valve 3 is switched.

In the above configuration, the three-way valve 3 is switched from the c-b connection to the c-a connection by the air purge control circuit of the circulation path 5, and the solenoid valve 7 is closed. Simultaneously with this switching of the water supply path, a cancel signal is applied from the cancel signal generating circuit 13 to the base of the third transistor Q3 for a predetermined time T, the third transistor becomes conductive, and the base power supply circuit of the first transistor Q1 is turned on. third transistor Q3
grounded via. As a result, the first transistor Q1 becomes non-conductive for the predetermined time T, and the reference voltage is maintained at the high reference voltage V _REFH .
No longer affected by damped waves.

That is, the attenuated wave reaches the high reference voltage as shown in Figure 4.
Even if it converges after overcoming V _REFH , the reference voltage of comparator circuit 10 remains V _REFH , and since the predetermined water level corresponding to the voltage of V _REFH has not yet been reached, water supply continues without closing solenoid valve 9. be.

With this configuration, at the same time as the water supply route is switched, the output of the hysteresis circuit is maintained at the high reference voltage for a predetermined period of time by the hysteresis cancel circuit, and the hysteresis function of the hysteresis circuit is stopped. Therefore, by setting the predetermined time to be sufficiently longer than the attenuation period of the water hammer phenomenon, malfunctions due to attenuated waves of the water hammer phenomenon can be prevented.

Although the hysteresis function was utilized here using a hysteresis circuit using a transistor, a microcomputer (microcomputer) may also be used.
In this case, the output of the pressure sensor may be input to the microcomputer after A/D conversion, and the output of the pressure sensor may be read into the microcomputer after a predetermined period of time has passed after switching the water supply route.

(Effect of the invention) As described above, according to the invention, there is provided a voltage level determining means for determining whether the output of a pressure sensor exceeds a predetermined reference voltage, and a means for determining whether the output of a pressure sensor exceeds a predetermined reference voltage; Since a canceling means is provided for inactivating the voltage level determination means for a predetermined period of time from the time of switching to the circulation route, malfunction of the control circuit due to the attenuated wave of the water hammer phenomenon that occurs when the water supply route is switched is prevented. can be prevented.

[Brief explanation of drawings]

Fig. 1 is an electrical circuit diagram of one embodiment of the present invention;
3 is a schematic diagram of an automatic water supply mechanism according to the present invention, FIG. 3 is an input voltage diagram of the voltage level determination circuit of FIG. 1, and FIG. 4 is a time chart of an embodiment of the present invention. 1... Pressure sensor, 2... Pump, 3... Three-way valve, 4, 5... Circulation path, 9... Solenoid valve, 10...
Voltage level determination circuit, 12... cancel circuit,
13... Cancel signal generation circuit.

Claims (1)

[Scope of utility model registration request] Water is supplied to the aquarium by a pump, and the water supply is stopped when a predetermined water level is detected by a pressure sensor.There are multiple conveyance paths from the pump to the aquarium, one of which is equipped with a pressure sensor, and these conveyance paths are In an automatic water supply mechanism provided with a switching valve, there is provided a voltage level determining means for determining whether the output of the pressure sensor exceeds a predetermined reference voltage, and a voltage level determining means for determining whether the output of the pressure sensor exceeds a predetermined reference voltage; A water pressure detection circuit in an automatic water supply mechanism, characterized in that it is provided with a cancel means for putting the means into an inoperable state.