JPH0377523B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a hot water mixing device for automatically mixing hot water and water to obtain mixed hot water at a desired temperature.

Configuration of Conventional Example and Its Problems As shown in FIG. A water side valve body is fixed to a valve shaft 7 and driven by a DC servo motor 10 via a screw feed mechanism 8 and a speed reducer 9. The mixed water temperature is detected by a mixed water temperature detector 11 and compared with a signal from a temperature setting device 12, and the error signal is amplified by an amplifier circuit 13 to drive a DC servo motor 10 (hereinafter simply referred to as motor 10).

FIG. 2a shows the relationship between temperature error and motor speed in the conventional example. At the point (1) where the amplified value of the temperature error becomes the motor starting voltage, the motor starts rotating and as the temperature error increases, the motor speed increases in proportion to it.
The maximum speed is reached at point (2), which is determined by the power supply voltage of the amplifier circuit. The proportional operation range is between (1) and (2).If the temperature error is negative, the motor rotation direction is reversed and the same operation occurs.

FIG. 2b shows temporal changes in the operation of the conventional example. When the setting is changed with the temperature setting device 12 at (3), the motor 10 rotates at the maximum speed, and when it enters the proportional operation range at (4), the motor 10 gradually reduces its speed.
The mixed hot water slowly approaches the set temperature and the motor stops at (5). The time it takes for the mixed hot water to stabilize becomes shorter as the proportional gain of the motor speed with respect to the temperature error increases, but there is a limit due to stability during steady state.

Furthermore, when the mixed hot water is stopped flowing, the flow in the mixing passage 3 stops, and the water temperature near the thermistor 11 decreases.
The valves move to a position where the hot water side valve body 5 is fully open and the water side valve body 6 is fully closed. When dispensing hot water is restarted in step (6), the hot water side valve body is fully open, so first, in step (7), the mixed water temperature becomes higher than the set temperature, and then the motor 10 starts rotating and gradually corrects the mixed water temperature ( The motor stops at 8).

Due to the above-described operation, the conventional hot water mixing device has the following drawbacks.

1 The response of the mixed water temperature is poor when changing the set temperature.

2 Overshoot is likely to occur because the valve is driven only after the mixed water temperature is detected.

3. Hot water comes out when the hot water starts. Moreover, it is dangerous because it takes time to stabilize.

OBJECTS OF THE INVENTION The present invention solves these conventional problems, and aims to provide a quick response when changing temperature settings, suppress the occurrence of overshoot, and eliminate the generation of dangerous hot water.

Structure of the Invention In order to achieve this object, the present invention provides a mixing valve that differentially adjusts the opening degree of a water passage and a hot water passage, a driving part that drives the mixing valve, and a driving part that drives the mixing valve. a valve position detector that detects a valve position; a mixing passage that merges the water passage and the hot water passage to obtain mixed hot water; and a water temperature detector provided in the water passage;
A hot water temperature detector provided in the hot water passage, a mixed hot water temperature detector provided in the mixing path, a temperature setting device for setting the mixed hot water temperature, the water temperature detector, the hot water temperature detector, and the temperature setting. an initial valve position setting circuit that calculates the valve position based on three signals of the valve position detector; a valve drive circuit that compares the signal of the initial valve position setting circuit with the signal of the valve position detector to control the drive unit; The hot water mixing device includes the mixed water temperature detector and a temperature error detection circuit that outputs a signal to the valve drive circuit to correct the valve position based on the signal from the temperature setting device so that the temperature error is eliminated.

With this configuration, the valve is quickly driven to a predetermined valve position corresponding to the set temperature based on the signals from the hot water temperature detector and the water temperature detector, and the valve position is further corrected using the signal from the mixed water temperature detector. , has good responsiveness when changing the set temperature, and has the effect of suppressing unnecessary overshoot and generation of hot water.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. 3, 4, 5, and 6. Note that the first
Parts that are the same as those in the figure are given the same numbers.

In FIG. 3, in a mixing valve main body 4 having a hot water passage 1, a water passage 2, and a mixing passage 3, a hot water side valve body 5 that adjusts the opening degree of the hot water passage 1 and a hot water side valve body 5 that adjusts the opening degree of the water passage 2 are used. The water-side valve body 6 is connected to the valve shaft 7 by being urged by a spring 14 and abutting against a retaining ring 15 . The valve bodies 5 and 6 are free to slide with respect to the valve shaft 7, and the spring 14
creates a relief when each valve body is fully closed. The valve shaft 7 is linearly driven by a step motor 10 (hereinafter simply referred to as a motor) via a screw feed mechanism 8 and a speed reducer 9. Signals from the hot water temperature detector 16 in the hot water passage 1, the water temperature detector 17 in the water passage 2, and the temperature setting device 12 are led to an initial position setting circuit 18. The signal from the mixed water temperature detector 11 in the mixing passage 3 and the signal from the temperature setter 12 are compared and amplified by a temperature error detection circuit 19. The limit switch 20 uses a switch lever 21 connected to the valve shaft to detect the valve position when the hot water side valve body is fully closed. A signal from the limit switch 20 is applied to the reset terminal of the counter 22, and drive pulses corresponding to forward and reverse rotation of the motor of the valve drive circuit 23 are applied to the up-count and down-count terminals. The output signal of the counter 22 is compared with the output signal of the initial position setting circuit 18 and applied to the valve drive circuit 23, and the output signal of the temperature error detection circuit 19 and the output signal of the counter 22 are guided to the movement range limiting circuit 24. The output signal of the movement range limiting circuit 24 is guided to the valve drive circuit 23. The valve drive circuit receives the input signal and generates a drive signal for the step motor 10.

Figure 4 shows the change in the amount of hot water and the amount of water with respect to the valve position (axial displacement of the valve shaft 7).If the pressures of hot water and water are equal, the flow rate ratio of hot water and water is almost determined by the valve position at the end of the mixing passage 3. Even when the overall flow rate is reduced, the absolute value of each flow rate changes, but the flow rate ratio remains almost unchanged. Therefore, if the hot water temperature and water temperature are known, the valve position for the required mixed hot water temperature can be approximately determined.

Next, the operation of this embodiment will be explained using the flowchart shown in FIG. 5 and the operation characteristic diagram shown in FIG. 6. Fifth
In the figure, when starting operation, first move the motor with a until the limit switch 20 is turned on,
The counter 22 is reset to become the reference position for the valve position. Thereafter, since the counter 22 counts the driving pulses of the step motor, the absolute position of the valve can be known. Next, in Figure 5b, set temperature,
The mixture ratio is determined from the hot water temperature and the water temperature, and the step motor 10 is driven at the maximum speed to move the valve to the initial position shown in FIG. 4 (FIG. 4-1) (FIG. 5c). In Fig. 5 d, a correction pulse with a frequency proportional to the temperature error is generated, and if the value of the counter that detects the valve position is within the determined correction operation range (Fig. 4 2), the correction pulse is applied to the motor for correction. do. When the temperature error disappears, the frequency of the correction pulse is zero, so the motor stops (e to f). In g, changes in the set temperature, hot water temperature, and water temperature are detected, and if there is a change, the process returns to h, and if there is no change, the process returns to i and repeats the operation.

In FIG. 6, after the reference position of the valve is determined, the motor drives the valve at maximum speed to the valve initial position (1). From t ₁ , the valve position is corrected at a speed according to the temperature error, and when the temperature error disappears, the motor stops at t ₂ . Since the valve moves slowly between t ₁ and t ₂ , no overshoot occurs. Variations in the mixing ratio with respect to the valve position, errors in initial settings, changes in hot water supply pressure, etc. are absorbed by the feedback operation during this period, and an accurate mixed water temperature is obtained. t ₃
When the set temperature is changed, the motor drives the valve again at maximum speed to the new valve initial position (2), and the correction operation is performed in the same manner until the temperature error disappears.

When dispensing hot water is stopped at t ₄ , the mixed hot water temperature decreases due to heat radiation, the hot water side valve element opens, and the water side valve element starts correction operation in the direction of closing, but at t ₅ , the correction operation range is exceeded, so the valve does not move any further. doesn't move. When hot water starts dispensing again at t ₆ , the valve position has not moved much from the initial setting position (2), so hot water will not be dispensed suddenly.
Only a slight overshoot occurs at t ₇ , which is quickly corrected and the mixed water temperature stabilizes.

Effects of the Invention As described above, according to the hot water mixing device of the present invention,
The following effects can be obtained.

(1) A water temperature detector is installed in the water passage, a hot water temperature detector in the hot water passage, and a valve position detector that detects the valve position. The mixing valve is driven at high speed in advance to the valve initial position determined by the initial position setting circuit based on the signal from the detector, and the temperature error detection circuit is further driven by the mixing water temperature sensor installed in the mixing passage and the setting signal from the temperature setting device. Since the valve position is corrected to eliminate temperature errors, the response when changing the temperature setting is extremely fast, and the hot water temperature stability during steady state is also good, allowing the desired mixed hot water temperature to be quickly obtained.

(2) The valve position detector consists of a limit switch that detects one end of the valve movement range and a counter that counts motor drive pulses, so the limit switch can be used in common with the limit switch for stopping the motor, without complicating the structure. It can be realized,
Can be done at low cost. Further, when the control circuit is configured with a microcomputer, the counter can be realized by software and does not require any external circuit, so that a low-cost device can be provided.

(3) The range of movement of the valve position correction by the mixed water temperature sensor is limited to a small range centered around the initial valve position, which prevents the valve from moving more than necessary due to excessive changes, making it possible to obtain a stable water temperature. . In particular, it is possible to prevent the generation of dangerously high-temperature hot water when hot water is restarted after temporarily stopping hot water.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a conventional hot water mixing device;
Figure 2 is an operating characteristic diagram of the conventional example, Figure 2a is a characteristic diagram showing the relationship between temperature error and motor speed, and Figure 2b is a characteristic diagram showing the relationship between temperature error and motor speed.
is a characteristic diagram showing set temperature, mixed water temperature, and motor speed with respect to time, FIG. 3 is a configuration diagram showing an embodiment of the present invention, and FIG. 4 is a diagram showing valve position versus water volume and hot water volume in an embodiment of the present invention. FIG. 5 is a flowchart showing the operation of an embodiment of the present invention. FIG. 6 is a diagram showing the operation of set temperature, mixed water temperature, motor speed, and valve position with respect to time in an embodiment of the present invention. It is a characteristic diagram. 1...Hot water passage, 2...Water passage, 3...Mixing passage, 4...Mixing valve body, 5...Hot water side valve body, 6...
Water side valve body, 7... Valve stem, 10... Step motor, 11... Mixed hot water temperature detector, 12... Temperature setting device, 16... Hot water temperature detector, 17... Water temperature detector,
18...Initial position setting circuit, 19...Temperature error detection circuit, 20...Limit switch, 22...Counter, 23...Valve drive circuit, 24...Movement range limiting circuit.

Claims (1)

[Scope of Claims] 1. A mixing valve that differentially adjusts the opening degree of the water passage and the opening degree of the hot water passage, and a drive unit that drives the mixing valve;
a valve position detector that detects the valve position of the mixing valve;
a mixing passage that merges the water passage and the hot water passage to obtain mixed hot water; a water temperature detector provided in the water passage; a hot water temperature detector provided in the hot water passage; a mixed water temperature sensor, a temperature setting device for setting the mixed water temperature, an initial valve position setting circuit that calculates the valve position based on three signals from the water temperature sensor, the hot water temperature sensor, and the temperature setting device; a valve drive circuit that controls the drive unit by comparing a signal from an initial valve position setting circuit with a signal from the valve position detector;
A hot water mixing device comprising the mixed water temperature detector and a temperature error detection circuit that outputs a signal for correcting the valve position so that a temperature error is eliminated based on the signal from the temperature setting device to the valve drive circuit. 2. The driving unit according to claim 1, wherein the driving part is a step motor, and the valve position detector comprises a limit switch that detects one end of the movement range of the mixing valve, and a counter that counts the driving pulses applied to the step motor. Hot water mixing device. 3. A movement range limiting circuit that limits the movement range of the valve position correction by the temperature error detection circuit to a smaller value than the entire movement range of the mixing valve, centered on the initial valve position determined by the water temperature detector, hot water temperature sensor, and temperature setting device. A hot water mixing device according to claim 1, which is provided with: