JPH0331970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a water heater, and particularly to a feed forward controlled water heater.

(Prior Art) Conventionally, feed-forward control type water heaters calculate the required combustion amount based on the deviation between the set temperature and the inlet water temperature and the water flow rate, and control the combustion control valve according to the calculated amount. Furthermore, the fuel control valve is controlled with an output higher than the calculated required combustion amount for a certain period of time at the beginning of tapping, thereby accelerating the rise of the tapping temperature and shortening the time it takes to reach the set temperature. Some ideas are being considered.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional method, the time for controlling the fuel control valve to exceed the required combustion amount is always constant, so, for example, optimal characteristics cannot be achieved at a set temperature that is commonly used. If the above-mentioned time is set so that the set temperature is low, the set temperature may be overshot, and there is a risk of unexpected hot water being discharged. On the other hand, if the above-mentioned time is set too short, the effect of improving the rising temperature of the tapped water can hardly be expected when the set temperature is high. Furthermore, the hot water supply characteristics change depending on the water flow rate and the water supply temperature in summer and winter, and the hot water supply characteristics also deteriorate depending on the conditions.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned conventional problems, and to provide a water heater that accelerates the temperature rise of hot water depending on various conditions and improves the hot water characteristics.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following configuration. That is, it includes an outlet hot water temperature setting means, an inlet water temperature detecting means, a water flow rate detecting means,
In a device that calculates the required combustion amount based on the deviation between the set temperature and the incoming water temperature and the water flow rate and controls the fuel control valve, the fuel control valve is controlled to be higher than the required combustion amount for a predetermined period of time at the beginning of hot water dispensing, and A control means is provided for variably setting the predetermined time based on at least one of the deviation between the set temperature and the inlet water temperature and the water flow rate.

(Function) At the beginning of hot water dispensing, the fuel control valve is controlled to a combustion amount obtained by adding, for example, a certain amount to the required combustion amount, which is calculated based on the value obtained by multiplying the deviation between the set temperature and the incoming water temperature by the water flow rate. . The above control is executed for a predetermined time set as a function of at least one of the deviation between the set temperature and the inlet water temperature and the water flow rate, and after the predetermined time period, the combustion amount is controlled to the required combustion amount. That is, when the deviation is small, the predetermined time is set to be short, and when the deviation is large, the predetermined time is set to be long, and when the amount of water flowing is large, the predetermined time is set to be short, and when the amount of water flowing is small, the predetermined time is set to be long. Then,
The above-mentioned predetermined time is varied according to the deviation and water flow rate, so that the optimal rise in the hot water outlet temperature according to the conditions can be obtained, the hot water outlet temperature will not overshoot, and the difference in water inlet temperature between summer and winter can be adjusted. The hot water supply characteristics will not be significantly deteriorated due to differences in water volume.

(Example) An example of the present invention will be described with reference to the drawings. 1 is a water supply pipe, 2 is a heat exchanger, and 3 is a hot water outlet pipe, and the water supply pipe 1 is provided with an inlet water temperature detection means 4 and a water flow rate detection means 5. Reference numeral 6 denotes a burner, and a fuel control valve 8 is interposed in a fuel supply path 7 to the burner 6 to adjust its valve opening according to an electrical signal.
Reference numeral 9 denotes a hot water tap temperature setting means operated by the user, and is electrically connected to the control means 10.

As shown in FIG. 2, the control means 10 includes a combustion amount calculation section 10a, a time setting section 10b, and a combustion control section 10c.
During steady hot water dispensing, the deviation between the set temperature TS set by the outlet temperature setting means 9 and the inlet water temperature TC detected by the inlet water temperature detection means, and the water flow rate detected by the water flow rate detection means 5. Based on Q, the required combustion amount G is calculated in the combustion amount calculating section 10a. That is, calculate G=(TS-TC)×Q×K. K is thermal efficiency. This result is then output to the fuel control valve 8 via the combustion control section 10c. The fuel control valve 8 controls the amount of fuel supplied to the burner 6 by varying the electromagnetic force according to the current value output from the combustion control section 10c, for example, and moving the valve up and down.

At the beginning of hot water tapping, the fuel control valve 8 is controlled to the combustion amount obtained by adding a certain amount (ΔG) to the above-mentioned required combustion amount G for a predetermined period of time, and after the predetermined period of time, the fuel control valve 8 is controlled to the required combustion amount G. That is, when the water flow rate detection means 5 detects that the faucet is opened, the time setting section 10b sets a predetermined time ts according to the deviation between the set temperature and the water inlet temperature and the water flow rate, and this predetermined time ts is a constant amount (△G) to the calculated required combustion amount G
The fuel control valve 8 is set to the combustion amount (G+ΔG). Due to this excessive amount of combustion, the temperature of the hot water rapidly approaches the set temperature, and the temperature rises quickly.

Figures 3 and 4 are hot water output characteristic diagrams in this embodiment. Figure 3 shows the case where the water flow rate is the same but the deviation between the set temperature and the water inlet temperature is different. As shown by the solid line, the set temperature When TS1 is high and the deviation from the inlet water temperature TC is large, the predetermined time ts1 for controlling the excessive combustion amount is set long, and when the set temperature TS2 is low and the deviation is small, as shown by the dashed line, the predetermined time ts1 is set longer. Accordingly, the predetermined time ts2 is set short, so that the hot water temperature setting is not overshot.

Figure 4 shows the case where the deviation between the set temperature TS and the inlet water temperature TC is the same. In this case, when the water flow rate is large (solid line), the temperature rises faster in terms of time, so the predetermined time ts3 is Set short. When the flow rate of water is small (dotted chain line), the predetermined time ts4 is set longer in inverse proportion to improve the rise characteristics of the tapped water temperature. In addition, by setting the predetermined time in proportion to the deviation between the set temperature and the incoming water temperature, or inversely proportional to the water flow rate, the hot water output characteristics can be improved even if only one of them is used. However, by making the predetermined time a function of both the deviation and the water flow rate, good hot water tapping characteristics can be obtained under all conditions.

(Effects of the Invention) The present invention has the following excellent effects. In other words, set temperature, water inlet temperature,
It is possible to always obtain a good rise in temperature at the outlet depending on the water flow rate conditions, and there is no risk of the outlet temperature overshooting and unexpectedly high temperature, and the temperature can be rapidly brought close to the set temperature. This greatly improves the usability of the eid-forward control type water heater.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention.
Figure 2 is a diagram of the overall configuration, Figure 2 is a functional block diagram of the main parts, Figure 3 is a diagram of hot water output characteristics when the water flow rate is constant,
FIG. 4 is a hot water supply characteristic diagram when the temperature deviation is constant. 4... Incoming water temperature detection means, 5... Water flow rate detection means, 8... Fuel control valve, 9... Hot water temperature setting means, 10... Control means.

Claims (1)

[Claims] 1 In a device that is equipped with a hot water outlet temperature setting means, an incoming water temperature detection means, and a water flow rate detection means, and which calculates the required combustion amount based on the deviation between the set temperature and the inlet water temperature and the water flow rate and controls the fuel control valve, control means is provided for controlling the fuel control valve to maintain the required combustion amount or more for a predetermined time, and for variably setting the predetermined time based on at least one of the deviation between the set temperature and the water inlet temperature, and the water flow rate. A water heater characterized by: