JPH0620041Y2 - Mixing servo controller - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to a mixing servo control device for a water heater, etc., and particularly due to malfunctions when the flow rate is reduced or the set temperature is changed to a low temperature. The present invention relates to a mixing servo control device such as a water heater that prevents fire extinguishing.

(Prior Art) Conventionally, as a water heater or the like using a mixing servo for hot water temperature control, for example, as shown in FIG. 1, an inlet channel (11) is provided with a high temperature side circuit (12) and a bypass channel (13). Mixing servo between hot water that has been branched and has passed through the heat exchanger (5) interposed in the high temperature side circuit (12) and has been heated to a predetermined high temperature, and cold water that has passed through the bypass channel (13) (1) In order to obtain a predetermined hot water temperature. The hot water temperature is measured by the incoming water temperature sensor.
Water temperature detected by (4), water temperature of high temperature side circuit (12) detected by water amount sensor (3), hot water temperature detected by hot water temperature sensor (2), and temperature setting means (9 ), The hot water mixing ratio and the heating amount that match the hot water temperature with the set temperature are calculated in the controller (6), and the controller (6) calculates the mixing servo according to the calculation result. By controlling the mixing ratio of hot and cold water and the heating amount of (1), the temperature is controlled to the set temperature. Further, when the amount of water in the high temperature side circuit (12) falls below a constant minimum control flow rate MOQ _OFF , a burner (not shown) is extinguished.

(Problems to be solved by the invention) However, in this conventional mixing servo control device, when the flow rate is decreased or the set temperature is changed to a low temperature, the boiling water becomes high due to the post-boiling due to the delay of the control, The hot and cold water mixing ratio is calculated so that the flow rate on the bypass water channel (13) side is increased more than necessary. As a result, even if it is not necessary to extinguish the fire from the viewpoint of the total amount of water, the amount of water in the high temperature side circuit (12) may fall below a certain minimum control flow rate MOQ _OFF to be extinguished.

The present invention has been made in view of the above circumstances, and a mixing servo control device for a water heater or the like for preventing fire extinguishing due to malfunction when the flow rate is reduced or the set temperature is changed to a low temperature. It is intended to provide.

(Means for Solving Problems) A mixing servo control device for a water heater or the like according to the present invention is
In order to achieve the above object, the amount of water detected by the water amount sensor interposed in the high temperature side circuit is the minimum control flow rate MOQ.
Discriminating means for discriminating whether or not the flow rate has decreased to a predetermined reference flow rate slightly higher than _OFF, and operation of the mixing servo for a predetermined time after the discrimination means determines that the amount of water on the high temperature side circuit side has decreased to the reference flow rate. Is provided with a time-stopping means for stopping.

(Operation) According to the present invention, if the amount of water detected by the water amount sensor decreases to a predetermined reference flow rate that is slightly higher than the minimum control flow rate MOQ _OFF , the determining means determines that the amount of water on the high temperature side circuit side has decreased to the reference flow rate. After that, the operation of the mixing servo is stopped for a predetermined time after this, so that the amount of water in the high temperature side circuit is prevented from falling below the minimum control flow rate MOQ _OFF for a predetermined time, and after boiling due to a delay in control during that time. By extinguishing the rise of the hot water temperature caused by, the fire extinguishing due to a malfunction is prevented.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a mixing servo control device for a water heater or the like according to an embodiment of the present invention, and FIG. 2 is a flow chart showing the flow of the main part of a control program incorporated in the control circuit body. Is.

In the figure, the inlet water channel (11) is branched into a high temperature side circuit (12) and a bypass water channel (13) and passes through a heat exchanger (5) interposed in the high temperature side circuit (12) to reach a predetermined high temperature. The high-temperature water heated above and the cold water that has passed through the bypass channel (13) are mixed by the mixing servo (1) to obtain a predetermined hot water outlet temperature. (2) is a hot water temperature sensor provided in the hot water passage, (3) is a hot water inlet
The water amount sensor provided in (11) and the water temperature sensor (4).
(6) is the main body of the control circuit, the amount of water detected by the water amount sensor (3) interposed in the high temperature side circuit (12) is the minimum control flow rate MOQ.
A determination means (14) for determining whether or not the flow rate has decreased to a predetermined reference flow rate slightly above _OFF , and when this determination means (14) determines that the amount of water on the high temperature side circuit (12) side has decreased to the reference flow rate. Thereafter, the microcomputer is provided with a built-in time delaying means (15) for stopping the operation of the mixing servo (1) for a predetermined time.

In the above configuration, the control program is started when the flow rate is rapidly reduced or when the set hot water temperature is lowered (S1), and when it is determined that the hot water discharge temperature is higher than the set temperature (S2). ), whether the detected water amount by amount of water sensor (3) is the minimum controllable flow MOQ _OFF slightly exceed the predetermined reference flow rate (MOQ OFF ₊ alpha) above is determined
(S3). The amount of water detected by the water amount sensor (3) slightly exceeds the minimum control flow rate MOQ _OFF.
If it is less than ( _OFF + α), the time stop means 15 stops the mixing servo (1) for a predetermined time, and waits until the rise in the hot water temperature due to post-boiling is eliminated (S4, S
5) Exit the program and move to the normal control program.

If the hot water temperature is below the set temperature, close the mixing servo (1) to raise the hot water temperature (S6), or control the water volume detected by the water volume sensor (3) to the minimum control. when exceeding the predetermined reference flow rate exceeding the flow rate MOQ _OFF slightly (MOQ OFF ₊ alpha), the mixing servo (1) into After to lower the hot water temperature by increasing the amount of water by opening than currently (S7) normal Control program, etc.

(Effects of the Invention) As described above, according to the present invention, when the amount of water on the high temperature side circuit decreases, the mixing is performed at the opening that becomes a predetermined reference flow rate ((MOQ _OFF + α)) slightly exceeding the minimum control flow rate MOQ _OFF. Since the servo is stopped, it is possible to prevent fire extinguishing due to malfunction when the flow rate is reduced or the set temperature is changed to a low temperature.

[Brief description of drawings]

FIG. 1 is a block diagram of a mixing servo control device for a water heater or the like according to an embodiment of the present invention, and FIG. 2 is a flow chart showing the flow of the main part of a control program incorporated in the control circuit body. Is. (1) …… Mixing servo (3) …… Water quantity sensor (5) …… Heat exchanger (6) …… Control circuit body (11) …… Inlet channel (12) …… High temperature side circuit (13) …… Bypass waterway (14) …… Discrimination means (15) …… Time stop means

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. An inlet channel is branched into a high temperature side circuit and a bypass channel, and the high temperature water heated to a predetermined high temperature through a heat exchanger interposed in the high temperature side circuit and the bypass channel are passed. In the case where cold water and mixing water are mixed by a mixing servo to obtain a predetermined hot water temperature, intervene in the high temperature side circuit at least when the flow rate is decreased or the set temperature is lowered. And a determining unit that determines whether the amount of water detected by the water amount sensor has decreased to a predetermined reference flow rate that is slightly higher than the minimum control flow rate MOQoff, and the determining unit determines that the amount of water on the high temperature side circuit side has decreased to the reference flow rate. A mixing servo control device, comprising: a control circuit having a built-in time-stopping means for stopping the operation of the mixing servo for a predetermined time after the judgment.