JPH0159493B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a water heater that uses gas, oil, electricity, etc. as a heat source, and can provide hot water at a set temperature at any time by automatically controlling the amount of hot water supplied. Regarding temperature control.

Here, a temperature control device for a water heater that uses gas as fuel will be described as an example.

Configuration of conventional example and its problems As shown in FIG. 1, a conventional temperature control device for a water heater of this type replaces water with hot water by using a heat exchanger 2 to replace combustion heat in a gas burner 1 serving as a heat source. Provide hot water. The temperature controller 3 inputs the signal (TWI) from the incoming water temperature detector 4 and the signal (TWR) from the temperature setting device 5, and calculates the deviation of the signals (TER=TWR−TWI).
A predetermined combustion amount is determined from the deviation TER and the signal (F _w1 ) of the water amount detector 6, and the supply heat amount controller 7 is controlled to control the hot water temperature (TWO). The combustion amount Qg at this time is expressed by the following equation, where η is the heat exchange rate.

η・Qg=(TWR−TWI)×F _w1 Therefore, if the heat exchange coefficient of the heat exchanger is found,
You can control the hot water temperature. However, in this configuration, as shown in FIG. 3, the combustion amount range that can be stably controlled by the performance of the burner itself is limited to the minimum combustion amount Qmin to the maximum combustion amount Qmax. Therefore, the hot water temperature is determined naturally. For example, even though the temperature is set at point a, if the water volume is reduced to b, the outlet temperature will reach point c. If the set temperature and the outlet temperature differ in this way, the product becomes very inconvenient for users to use. Furthermore, if high-temperature water comes out, there is a problem in that the life of the water heater itself is shortened, which is extremely dangerous. Further, temperature control using P/I/D control or the like also has these problems.

Purpose of the invention The present invention solves such conventional problems,
The purpose is to control the combustion amount below the range that allows stable combustion in the burner.

Structure of the Invention In order to achieve this object, the present invention provides a burner for heating water flowing through a heat exchanger, a hot water tap for discharging hot water from the heat exchanger, and a temperature sensor for detecting the temperature of water flowing into the heat exchanger. The combustion amount of the burner depends on the deviation (TER) between the temperature setting device signal (TWI) and the temperature setting device signal (TWR) that sets the hot water temperature, and the signal (FW) of the water flow sensor flowing through the heat exchanger. and a temperature controller including a combustion amount determination unit that outputs a signal for determining and driving and controlling a supply heat amount controller of the burner;
The temperature controller is equipped with a safety control section that drives and controls a safety valve that is piped in parallel with the hot water faucet and discharges hot water to the outside when the signal from the combustion amount determining section falls below the minimum combustion amount of the burner for stable combustion. It is something that

With this configuration, when the amount of water flowing through the heat exchanger decreases and the hot water supply load falls below the minimum combustion amount of the burner, the safety valve is opened and the water is discharged to the outside, increasing the amount of water flowing through the heat exchanger. , has the effect of maintaining the hot water supply load above the minimum combustion amount capable of controlling the hot water temperature.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Note that the same members as in FIG. 1 are given the same numbers.

Combustion heat from a burner 1 serving as a heat source is converted into hot water by a heat exchanger 2, and hot water is supplied. The temperature controller 3 receives the signal from the inlet water temperature detector 4 (TWI), the signal from the temperature setting device 5 (TWR), and the signal from the water flow sensor (F _w1 ).
A predetermined combustion amount (Qg) is determined and the supply heat amount controller 7 is controlled. The amount of combustion mentioned above
When the calculation result of Qg becomes less than the minimum combustion amount (Qmin) for stable combustion control, the safety valve 9 installed parallel to the hot water tap 8 is opened and the amount of water flowing through the heat exchanger is changed. It controls the temperature of the hot water. Figure 4 shows control below Qmin.

Qg=1/η・(TWR−TWI) ・F _w1 ...(1) When Qg≦Qmin, for example, if the heat amount at point A is set, TWI is constant, so (TWR−TWI)
depends on the set temperature TWR, or because the combustion is below Qmin, the temperature rises to point c. Therefore, the water amount can be changed from point b to point d, and the temperature can be controlled within the range that can be controlled by the temperature controller.
can be kept. At this time, the amount of water flowing through the safety valve (F _w2 ) is determined by the following formula.

η・Qmin=(F _w1 +F _w2 ) (TWR−TWI) After deformation, F _w2 =η・Qmin/TWR−TWI−F _w1 ……(2) Therefore, at point B, the burner can be stably controlled. control is possible. The hot water discharged from the safety valve may be used for other purposes such as filling a bathtub.

The operation of the temperature controller 3 will be explained using a flow diagram in FIG. First, in the routine, set the hot water temperature on temperature setting device 5.
Input TWR, feed water temperature TWI, and feed water amount FWI, and calculate the combustion amount Qg of burner 1 using equation (1) in the combustion amount determination section. Here, the comparison section compares the minimum combustion amount Qmin and Qg determined by the burner. When Qg≧Qmin, the supply combustion amount controller 7
outputs an output corresponding to the combustion amount Qg (Fig. 5). If Qg<Qmin, the process moves to the safety control section, and the amount of water F _w2 to be discharged from the safety valve 9 is determined using equation (2), setting the value of Qg to Qmin. The safety valve 9 is driven by this value of F _w2 . At this time, a signal for supplying the burner 1 with a gas amount corresponding to Qmin is output to the supply heat amount control section 7.

In order to realize such a control device, methods such as management and execution of programmable control laws using a microcomputer, which have been widely used in recent years, and combinations of driving parts of each element may be considered.

Effects of the Invention As explained above, the water heater temperature control device of the present invention provides the following effects.

(1) When the hot water supply load falls below the minimum combustion amount of the burner, the safety valve discharges the hot water and increases the load, thereby preventing loss of temperature control and preventing abnormal high temperatures such as boiling. can be prevented. This makes it comfortable and safe, especially when using a shower that directly sprays hot water onto the human body.

(2) Also, since the amount of water discharged from the safety valve is set to a value that matches the load with the minimum combustion amount of the burner,
Prevent waste of fuel and water due to excess drainage.

(3) Since it is possible to prevent abnormally high temperature water from coming out of the water heater, damage to the water heater can be prevented and its durability can be extended.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a conventional gas water heater, FIG. 2 is a configuration diagram of a gas water heater according to an embodiment of the present invention,
Fig. 3 is a capacity characteristic diagram of a conventional water heater, Fig. 4 is a capacity characteristic diagram of the water heater of the present invention below the minimum combustion amount, and Fig. 5 is a diagram showing the temperature control algorithm of the water heater of the present invention. be. 1... Burner, 2... Heat exchanger, 3... Temperature controller, 4... Incoming water temperature detector, 5... Temperature setting device, 6... Water amount detector, 7... Supply heat amount controller,
8...Hot water faucet, 9...Safety valve,...Combustion amount determining section,...Safety control section, Qg...Combustion amount, Qmin...
...Minimum combustion amount.

Claims (1)

[Claims] 1 A burner that heats the water flowing through the heat exchanger,
A hot water faucet for dispensing hot water from the heat exchanger, an incoming water temperature detector for detecting the temperature of water flowing into the heat exchanger, a water amount detector for detecting the amount of water, and an amount of heat supplied to variably control the amount of heating heat of the burner. The controller controls the burner depending on the deviation (TER) between the water input temperature sensor signal (TWI), the temperature setting device signal (TWR) that sets the hot water temperature, and the water flow sensor signal (FW). and a temperature controller including a combustion amount determining section that determines the combustion amount and outputs a signal for driving and controlling the heat amount controller, and the temperature controller includes a burner that stably burns the signal from the combustion amount determining section. A temperature control device for a water heater, which is provided with a safety control section that drives and controls a safety valve that is piped in parallel with the hot water faucet and discharges hot water to the outside when the amount of hot water becomes less than the minimum combustion amount.