JPH0328663B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is a gas instantaneous water heater, in particular a burner that burns intermittently, and the water temperature is controlled by the ratio of the combustion time and the extinguishing time in the intermittent combustion cycle. The present invention relates to a control device for a gas instantaneous water heater.

(Prior Art) Conventionally, a gas instantaneous water heater which uses a burner to perform intermittent combustion and controls the hot water temperature by the ratio of the combustion time to the extinguishing time in the intermittent combustion cycle has been proposed in the patent application filed by the present applicant. No. 58-192695 (Unexamined Japanese Patent Publication No. 1983)
-82716).

This method calculates the required amount of heat based on the set temperature, water volume, incoming water temperature, etc., and opens and closes the solenoid valve at intervals and lengths according to the calculated value to cause the burner to burn intermittently. Unlike gas flow control, which continuously adjusts the opening degree of a proportional valve based on the required amount of heat that is continuously calculated, the amount of heat cannot be controlled continuously, but intermittently every cycle. Must be controlled.

Therefore, a big problem is when to determine the amount of heat required for the next cycle.

That is, in FIG. 3, for example, the ratio of the combustion time to the extinguishing time in the _T1 period, in other words, the ratio of the valve opening time to the valve closing time of the solenoid valve must be determined during the T period. The problem is when to make the decision based on the calculated required amount of heat.

For example, when the required amount of heat F changes as shown in Fig. 3, the ratio of the opening time and closing time of the solenoid valve for _T1 period is determined based on the required amount of heat calculated at the start point of the T period. There will be a big difference in the ratio of combustion time to digestion time in _T1 cycle depending on whether it is determined based on the required amount of heat calculated at the end of the T cycle. If this happens, the amount of heat will become too large, and it cannot be said that there is no risk of bumping occurring.

(Problem to be Solved by the Invention) The problem to be solved by the present invention is that the ratio of the combustion time to the digestion time in each intermittent combustion cycle is determined based on the average of the required amount of heat calculated during the immediately preceding cycle. It is to decide.

(Means for Solving the Problems) The technical means taken by the present invention to solve the above problems include a water flow sensor and an inlet water temperature sensor provided in the water supply pipe in the control circuit, a temperature setting device provided in the control box, and a temperature setting device provided in the control box. Required heat amount calculation means that continuously calculates the required heat amount based on the set temperature set by the temperature setting means, the detected value of each sensor, etc.;
Average required heat amount calculation means calculates the average value of the required heat amount calculated by the above-mentioned required heat amount calculation means during the immediately preceding solenoid valve opening/closing cycle, and the solenoid valve outputs the length and interval according to the calculated value of the average required heat amount calculation means. This constitutes an output generating means for generating.

The configuration of the present invention will be explained based on FIG.

A water amount sensor and an incoming water temperature sensor provided in each water supply pipe constantly detect the amount and temperature of water supplied to the heat exchanger. The detected values of each of the above sensors serve as calculation elements for calculating the required heat amount, and the required heat amount calculation means constantly and continuously calculates the required heat amount based on the detected value of each sensor, the set temperature set by the temperature setting means, etc. Calculate.

From this continuously calculated required heat amount, the average value of the required heat amount during each intermittent combustion cycle is calculated by the average required heat production calculation means, and the output generation means is used for the next cycle. An output having a length and interval corresponding to the above average value is generated, and the solenoid valve opens and closes according to the length and interval.

(Example) Hereinafter, an example of the present invention will be described based on a hot water supply apparatus equipped with a hot water circulation flow path as shown in FIG.

In Fig. 2, reference numeral a denotes a water heater, in which gas supplied through gas piping 1 is combusted in a burner 2, water supplied through a water supply pipe 3 is heated in a heat exchanger 4, and the hot water supply pipe is heated by a heat exchanger 4. 5, the water flows to a hot water supply device 6 such as a faucet.

The gas pipe 1 is provided with a solenoid valve 7, a solenoid valve 8, and a governor 9 with the former on the upstream side.

On the other hand, a water flow sensor 10 and an incoming water temperature sensor 11 are sequentially installed in the water supply pipe 3 from the upstream side.
A hot water temperature sensor 12 is provided in each.

Further, the hot water supply pipe 5 branches a return pipe 13 from a midpoint thereof, more specifically near the hot water supply equipment 6, and connects the other end of the return pipe 13 to the water supply pipe 3 before the water amount sensor 10. .

A pump 14 is provided in the return line 13.

The pump 14 may be configured to operate only when hot water is not being dispensed from the water heater 6, or may be operated when the water heater a is in operation regardless of whether hot water is being dispensed from the water heater 6. However, for convenience of explanation, only the latter case will be explained below.

The pump 14 connects the hot water supply pipe 5 when supplying hot water to the water heater 6.
The hot water flowing through the pipe is drawn into the return pipe 13, and a small capacity pipe with a flow rate of about 2/min is installed so as not to obstruct the supply of hot water to the hot water supply equipment 6.

A solenoid valve 8 in the gas pipe 1, a water flow sensor 10 in the water supply pipe 3, an inlet water temperature sensor 11, an outlet water temperature sensor 12 in the hot water supply pipe 5, and a pump 14 in the return pipe 13.
are electrically connected to the control circuit 15, the water amount sensor 10 detects the amount of water flowing through the water supply pipe 3 and outputs a signal A, and the incoming water temperature sensor 11 detects the temperature of water entering the heat exchanger 4. The output hot water temperature sensor 12 detects the output water temperature from the heat exchanger 4 and sends the signal B and the signal C to the control circuit 15, respectively.

The control circuit 15 is disposed in the stand of the water heater a or in the control box 16, and when the operation switch 17 of the control box 16 is turned on, it sends a signal D to the pump 14 to rotate the pump 14.

Further, the control circuit 15 includes a required heat amount calculation means a,
It has an average required heat amount calculation means b and an output generation means c, and the required heat amount calculation means a receives the signals A, B,
The amount of water Q input by C, the inlet water temperature T _C ,
The required amount of heat F is calculated using the following equation based on the hot water tap temperature T _H , the set temperature T _S set by the temperature setting means 18 of the control box 16, and the gain α.

F=(T _S −T _C )Q+(T _S −T _H )α Moreover, the average required heat amount calculation means b is calculated during the intermittent combustion period T, which is the sum of the combustion time t ₁ and the digestion time t ₂ of the burner 2. Calculate the average value F ₁ of the required amount of heat F.

The average value F ₁ is theoretically determined by F ₁ =∫ ^T / ₀ Fδt/T, but normally the minimum combustion amount for stable combustion of burner 2, that is, the lowest number of water heater is the maximum combustion amount,
In other words, it is 1/4 to 1/5 of the maximum number of water heaters, so
Never burn near No. 0.

Therefore, in reality, the average value F ₁ is determined by F ₁ = t ₁ /T x lowest number x 25 (Kcal/min).

The output generating means c generates an output according to the above average value F ₁ in the form of a pulse signal having a length and an interval according to the average value F ₁ , and calculates the combustion time t ₁ ' and the digestion time in the next intermittent combustion period T ₁ . It is sent to the solenoid valve 8 as t ₂ '.

The relationship between the average value F ₁ of the required heat load in the above intermittent combustion period T and the combustion time t _{1 ′} and digestion time t ₂ ′ of the next intermittent combustion period T 1 is such that the combustion amount of burner 2 is the minimum required for stable combustion. When the amount of combustion is equivalent to No. 3, it is determined as follows.

() When F ₁ ≧25Kcal/min, F ₁ =t ₁ ′/T×3×25 (Kcal/min) T=t ₁ ′+t ₂ ′=6 (seconds).

∴t ₁ ′=F ₁ /25 × 2 (seconds) t ₂ =6−t ₁ ′ (seconds) () 2.5≦F ₁ ＜25Kcal/min F ₁ = t ₁ /T × 3 × 25 (Kcal / minute) T=t ₁ ′+t ₂ ′ (seconds) t ₁ ′=2 (seconds).

t ₂ ′=150/F ₁ −2=150−2F ₁ /F ₁ (seconds) Therefore, below, the pulse signal E corresponding to the average value F ₂ of the required amount of heat F in the intermittent combustion period T ₁ is expressed as follows. The combustion time t ₁ ″ and extinguishing time t ₂ ″ in the intermittent combustion period T ₂ are sent to the solenoid valve 8, and the intermittent combustion period T ₂
The pulse signal corresponding to the average value F ₃ of the required amount of heat F in the next intermittent combustion cycle T ₃ is the combustion time t ₁
〓 and extinguishing time t ₂ 〓 are sent to the solenoid valve 8, and thus,
The combustion time t ₁ of each intermittent combustion period T, T ₁ , T ₂ , T ₃ ...
The ratio of t ₁ ′, t ₁ ″, t ₁ 〓 and extinguishing time t ₂ , t ₂ ′, t ₂ ″, t ₂ 〓 is determined based on the average value of the required heat amount in the previous intermittent combustion cycle, and this is repeated to send the required pulse signal to the solenoid valve 8.

The solenoid valve 8 receives the pulse signal E, and according to the length and interval of the pulse, it opens during the combustion time _t1 , opens during the extinguishing time _t2 , and opens and closes at a determined ratio.

That is, _each cycle of intermittent combustion in the burner 2 is determined based on the length and interval of the pulses of the pulse signal E, that is, the average value F ₁ of the required amount of heat F in the immediately preceding intermittent combustion _cycle . Burns with ratio.

First, when the operation switch 17 of the control box 16 is turned on with the hot water side valve of the water heater 6 closed, the hot water temperature sensor 12 detects that the water temperature in that part has not reached the set temperature. Detecting this, the control board 15 starts calculating the required amount of heat F, and at the same time, the pump 14 starts rotating, the main solenoid valve 7 opens, the solenoid valve 8 opens and closes, and the burner 2 starts intermittent combustion. start.

Therefore, water in the pipes is circulated from the water supply pipe 3 through the heat exchanger 4 , the hot water supply pipe 5 , and the return pipe 13 to return to the water supply pipe 3 in front of the water flow sensor 10 by the operation of the pump 14 . It flows and is heated as it passes through the heat exchanger 4.

At this time, the intermittent combustion of the burner 2 is controlled by the control board 15.
The combustion time t ₁ and extinguishing time t ₂ of each intermittent combustion cycle are
The ratio of is the required heat amount F in the immediately preceding intermittent combustion cycle.
is determined and controlled based on the average value of
The circulating water is boiled to the set temperature and maintained at the set temperature.

Next, when the hot water side valve of the water heater 6 is opened, the hot water that has already been boiled to the set temperature in the piping is supplied to the hot water heater 6, and then water is newly supplied from the water supply pipe 3 to the set temperature. Supplied heated.

Note that when hot water is used by the water heater 6, the amount of water, the temperature of the incoming water, etc. naturally change from those during the above-mentioned circulating flow, that is, when the hot water is not in use. 15 with signals A and B, and accordingly, the intermittent combustion of the burner 2 is continuously optimally controlled by the control circuit 15 to ensure that hot water at the set temperature continues to be supplied.

At this time, the pump 14 continues to operate, but
Because the capacity is small, hot water from hot water supply pipe 5 is returned to pipe 13.
There is no possibility that the hot water will be drawn in and prevent sufficient hot water from being supplied to the hot water supply equipment 6.

Then, when the hot water side valve of the water heater 6 is closed, the supply of new water to the water heater a is stopped, and the hot water in the piping is maintained at the set temperature while circulating and flowing again.
Waiting for the next use of the water heater 6.

Although the above embodiment describes a water heater having a hot water circulation path, the present invention is not limited thereto, and it is of course possible to apply the control device of the present invention to a water heater that does not have a hot water circulation path.

In addition, in the above embodiment, the hot water outlet temperature T _H is included as an element of the required heat amount calculation, but the hot water outlet temperature is not included.
The required amount of heat may be calculated based only on the water amount Q, the water inlet temperature T _C , and the set temperature T _S . The arithmetic expression in this case is F=(T _S -T _C )Q.

(Effects of the Invention) The outlet temperature is controlled by causing the burner to perform intermittent combustion, and determining the ratio of the combustion time and extinguishing time of each intermittent combustion cycle based on the average value of the required amount of heat in the immediately preceding intermittent combustion cycle. Therefore, in response to changes in the amount of heat required due to unpredictable external factors, that is, ups and downs and their speeds, it is possible to continue to control the amount of heat required for each intermittent combustion cycle in advance so that there is almost no excess or deficiency. There is no risk of bumping, and there is little hunting in the water temperature.

By reducing the ratio of combustion time to extinguishing time, it is possible to output burner size close to 0, which eliminates the need to prepare several models for each capacity with gas proportional control. , a single machine is sufficient;
Furthermore, even under a required output close to No. 0, it is possible to perform intermittent control with almost no excess or deficiency of the desired amount of heat originally required under that state.

[Brief explanation of drawings]

Fig. 1 is a claim correspondence diagram explaining the configuration of the present invention, Fig. 2 is a schematic configuration diagram of a control device for a gas instantaneous water heater showing an embodiment of the present invention, and Fig. 3 is a diagram showing the requirements for each intermittent combustion cycle. This chart shows the relationship between the amount of heat and the ratio of burner combustion time to extinguishing time, where T, T ₁ , T ₂ , and T ₃ are each intermittent combustion period, and t ₁ and
t ₁ ′・t ₁ ″・t ₁ is the combustion time, t ₂・t ₂ ′・t ₂ ″・t ₂ 〓 is the extinguishing time, F is the required amount of heat, and F ₁・F ₂・F ₃ are the average values. . The fourth is the average amount of heat required during the intermittent combustion cycle.
This is an explanatory diagram showing the relationship between F ₁ and the period length of the next intermittent combustion cycle. When F ₁ ≧25Kcal/min,
The cases of 2.5≦F ₁ <25Kcal/min are shown respectively. 1: gas piping, 2: burner, 3: water supply pipe,
4: Heat exchanger, 5: Hot water supply pipe, 8: Solenoid valve, 1
0: Water flow sensor, 11: Inlet water temperature sensor, 1
5: Control circuit, 16: Control box, 1
8: Temperature setting means, a: Required heat amount calculation means, b:
Average required heat amount calculation means, c: output generation means.

Claims (1)

[Claims] 1 A burner, a heat exchanger that connects the water supply pipe and the hot water supply pipe, and a solenoid valve that is installed in the gas pipe that connects the gas supply source and the burner and that opens and closes according to the length and interval of the output signal from the control circuit. This is a control device for a gas instantaneous water heater that controls water temperature based on the ratio of intermittent combustion combustion time and extinguishing time of a burner by opening and closing a valve. Water temperature sensor, temperature setting means provided in the control box, required heat calculation means that continuously calculates the required heat based on the set temperature set by the temperature setting means and the detected value of each sensor, during the immediately preceding solenoid valve opening/closing cycle. average required heat amount calculation means for calculating the average value of the required heat amount calculated by the above-mentioned required heat amount calculation means; A control device for a gas instantaneous water heater, comprising: