JPH0123071Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a control device for a proportional control type instantaneous water heater.

(Problems to be solved by conventional technology and ideas) Conventionally, as a control method for this type of instantaneous water heater, feedback control is used to proportionally control the gas amount according to the deviation between the outlet temperature and the set temperature. Common. However, since such feedback control is based on the control result, that is, the hot water temperature, when a disturbance occurs, for example, when the amount of water supplied changes, it takes a long time to control the temperature to the set temperature, making it difficult to respond. For this reason, even if a disturbance occurs, feedforward control is being adopted in which the gas amount is set based on the disturbance data.

Such feedforward control is performed at the set temperature To
Based on the water supply temperature Tw, water supply volume Q, and efficiency W, the gas volume G is calculated using the relationship G = (To-Tw) x Q/W, and the opening output corresponding to this gas volume G is sent to the gas proportional valve. It is something to give.

However, data other than the efficiency W can be measured and imported into the controller, but efficiency W cannot be measured.
was fixed at a constant value (e.g. 80%). However, since the efficiency W fluctuates with changes in the amount of hot water dispensed and the set temperature, when the efficiency W is set to a constant value, a difference (offset) occurs between the hot water dispensed temperature and the set temperature, resulting in extremely poor hot water dispensing characteristics.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a heat exchanger, a burner for heating the heat exchanger, a gas proportional valve interposed in the gas supply path leading to the burner, Based on the water supply temperature determined by the water supply temperature detector installed in the water supply channel connected to the heat exchanger, the water supply amount determined by the water flow rate detector, the set temperature by the set temperature controller, and the exhaust gas temperature determined by the exhaust gas temperature detector installed in the exhaust gas passage. The configuration includes a controller that calculates the amount of gas and controls the gas proportional valve.

(Function) When water supply starts, signals of the water supply temperature, water supply amount, set temperature, and exhaust gas temperature are input to the controller, and the controller calculates the actual efficiency from the exhaust gas temperature and uses the calculated efficiency to calculate the feed forward. The proportional valve is controlled by calculating the control amount.

(Example) The present invention will be specifically described below based on an illustrated example.

1 is an instantaneous water heater, 2 is a heat exchanger, and 3 is a burner that heats the heat exchanger 2. 4 is burner 3
5 is a water quantity detector provided in the water supply channel 6, and 7 is a water supply temperature detector. Reference numeral 8 denotes a set temperature controller, which is installed in a hot water supply area such as a kitchen. 9 is an exhaust gas temperature detector installed in the exhaust gas passage above the heat exchanger 2, and 10 is a sensor that calculates the gas amount based on the above-mentioned detection data and adjusts the coil current value to the opening corresponding to the gas amount. This is a controller that controls the gas proportional valve 4 in a manner similar to that shown in FIG.

In the above configuration, when hot water supply is started, the set temperature To, the water supply temperature Tw, the water supply amount Q, and the exhaust gas temperature T _E are input to the controller 10.

Generally, the exhaust gas temperature T _E and the efficiency W are inversely proportional as shown in FIG.
In this case, the efficiency W is calculated as W=α/T _E (α is a constant), and then the gas amount G is calculated as G=(To
-Tw)×Q/W to control the gas proportional valve 4.

In general, the efficiency of water heaters differs depending on product variations, as well as changes in the hot water supply conditions such as hot water temperature and hot water output amount, but if the above control is performed, for example, if the exhaust gas temperature _T is high, the efficiency W can be lowered. If the exhaust gas temperature _TE is low, the efficiency W is determined to be high and the gas amount G is decreased.
It controls the hot water temperature to the set temperature.

(Effects of the invention) As explained above, if control is performed using the exhaust gas temperature as in the present invention, the gas amount can be calculated using data that closely approximates the actual efficiency during hot water supply. The offset mentioned above becomes extremely small, and in addition, in the conventional method of detecting the hot water temperature and adding the feedback amount based on the deviation from the set temperature to the feedback control gas amount to eliminate the offset, the heat exchanger The thermal time constant of the heat mass etc. is large and the responsiveness is poor, whereas the present invention uses exhaust gas temperature, which changes faster than the hot water temperature changes, to provide good responsiveness and good hot water tapping characteristics. This makes it possible to provide an instant water heater.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an instantaneous water heater showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the relationship between exhaust gas temperature and efficiency. 2... Heat exchanger, 3... Burner, 4... Gas proportional valve, 5... Water amount detector, 6... Water supply channel, 7...
Feed water temperature detector, 8... Set temperature regulator, 9... Exhaust gas temperature detector, 10... Controller.

Claims (1)

[Scope of utility model registration request] A heat exchanger, a burner that heats the heat exchanger, a gas proportional valve installed in the gas supply path leading to the burner, and a water supply temperature and water flow rate detector installed in the water supply path connected to the heat exchanger. A controller for controlling the gas proportional valve by calculating the gas amount based on the water supply amount by the controller, the set temperature by the set temperature controller, and the exhaust gas temperature by the exhaust gas temperature detector provided in the exhaust gas passage. A control device for an instantaneous water heater.