JPH01169268A - On-off combustion controller for hot water supply device - Google Patents

Abstract

PURPOSE:To prevent instantaneous boiling and make temperature variation small by storing beforehand a suitable ON time of combustion in a computer by the inflow quantity per unit time and a required heat quantity and selecting an appropriate combustion ON-time from the required heat quantity and actual inflow rate and also calculating a combustion OFF-time. CONSTITUTION:The quantity of fed water, its temperature, and a set temperature are read in a microcomputer 16 to calculate a required heat quantify G1 per unit time, and from this calculated heat quantity and the inflow quantity Q1 a combustion ON-time is selected which is beforehand stored. In this case the whole area is divided into A area, B area, and C area and for each area a specified combustion ON-time is given. Because the required heat quantity G1 is small in the A area, a short combustion ON-time S is given, and because the required heat quantity G1 is large in B area, a middle combustion ON-time M is given, and because, in the C area, lifetime has priority, the large combustion ON-time L is given. A combustion OFF-time is calculated from those combustion ON-times and the required heat quantity G1 per unit time which is calculated, and the heat quantity of combustion per unit time G0 which the burner 3 of a hot water supply device possesses.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an on/off combustion control device for a water heater.

<Prior Art> As a water heater that performs on-off combustion control by feedforward control, a device described in Japanese Utility Model Application Laid-open No. 54-127249 has been provided. This device calculates the required amount of heat from the water temperature and flow rate entering the water heater, and the set hot water temperature,
The structure is such that one cycle time, combustion on time, and combustion off time necessary for on-off combustion are appropriately determined from this required amount of heat and the amount of combustion heat of the burner.

<Problems to be Solved by the Invention> According to the past experience of the present inventors, there are the following problems, particularly on the on-off combustion side '<III using the instantaneous heating method.

(1) In a small flow rate region, if the combustion on time is long, instantaneous boiling may occur within each combustion on time even if the total amount of heat due to on/off is appropriate.

(2) Even if the on-off time is the same in the small flow rate region and the large flow rate region, the variation in the outlet temperature is greater in the large flow rate region.

(3) If the combustion on-time is too short, problems such as ignition problems and soot generation will occur, so there is a limit to the duration of each on-off.

(4) The shorter the on-off cycle is, the smaller the variation in the hot water temperature will be, but the shorter the cycle, the shorter the service life will be.

In other words, in on-off combustion control of water heaters, simply determining the combustion on time, combustion off time, and one cycle time so that the required heat amount matches the combustion heat amount of the burner will not solve the above problems. This will result in a major hindrance to either of the following.

In the above-mentioned device of Utility Model Application Publication No. 54-127249 Koko 1, the cycle time of on-off combustion, the combustion on-time,
Since one of the combustion off times is simply set to a short fixed value and the remaining two times are simply calculated, this method still has the disadvantage of seriously interfering with any of the above-mentioned problems.

Therefore, the present invention solves the above-mentioned conventional problems, does not cause boiling phenomenon even when the flow rate is small, suppresses temperature fluctuations to a small extent, and extends the life of the water heater. The purpose is to provide a combustion control device.

<Means for Solving the Problems> The present invention is an on/off combustion control device for a water heater that combusts fuel and instantaneously heats water passing through a heat exchanger using the generated heat to supply hot water. , an inlet water temperature sensor, an inlet water flow rate sensor, an outlet water temperature setting device, and a controller with a built-in microcomputer. Memorize the time in advance,
Calculate the required amount of heat per hour from the actual temperature and flow rate of water entering the heat exchanger, and the set hot water temperature, and calculate the suitable combustion on time from the required amount of heat and the actual water flow rate. and calculates the combustion off time from the combustion on time, the required heat amount per unit time, and the combustion heat amount per unit time of the burner, and performs on-off repeated combustion by feedforward control. It is a feature.

A suitable combustion on time can be determined based on previously obtained data, depending on the capacity of the burner of the water heater. The combustion-on time can be determined by dividing the region represented by the inlet water flow rate and the required amount of heat as a vertical axis and a horizontal axis into a plurality of regions, and determining a suitable combustion-on time for each region. For example, in a region where the incoming water flow rate is small and the required heat h1 is also small, the combustion on time is set short enough to prevent ignition and soot problems, and short enough to prevent instantaneous boiling, and the incoming water flow rate is small. However, in areas where the required amount of heat is large, it is possible to extend the life by setting the combustion on time a little longer without boiling. In addition, in areas where the water input flow rate is small and the required amount of heat is small, the combustion on time is shortened (
Set. In addition, in areas where the incoming water flow rate is appropriate and the required amount of heat is appropriately large, this is an area where the frequency of use is very high, and the fluctuations in the outlet temperature do not deteriorate so much, so the combustion on time can be set relatively long. , the service life can be extended.

In this way, the present invention successfully covers various problems that may occur in water heaters by preparing in advance the combustion on time suitable for each region using the water inflow flow rate and the required amount of heat as parameters, and also achieves a good performance. It performs the necessary on-off combustion while maintaining the hot water discharge characteristics.

In this case, instantaneous boiling means that the temperature of the water that is being exchanged during combustion increases in temperature due to the heat exchange, and the water boils rapidly when combustion is turned off. It refers to boiling that occurs at any time, excluding the period when it is boiled.

<Function> The combustion on time and combustion off time required for feedforward control are the same! - Calculated in real time by a microcomputer inside the roller, and necessary control signals are output from the controller to the burner side.

In other words, the temperature information from the incoming water temperature sensor, the incoming water flow rate information from the incoming water flow rate sensor, and the set outlet temperature information from the outlet temperature setting device are microphoned and input into a computer at appropriate intervals, the required amount of heat is calculated, and the combustion An on time is selected and a combustion off time is calculated. Then, the burner is turned on and off during the combustion on time and combustion off time.

<Example> Fig. 1 is an overall configuration diagram of an implementation device of the present invention, Fig. 2 is an on-off combustion control flowchart 1 by a controller, and Fig. 3 is an example of combustion on time using the inlet water flow rate and required heat amount as parameters. FIG.

An instant heating type heat exchanger 2 and a burner 3 are provided within the combustion envelope 1. The burner 3 is blown with air and supplied with fuel through a fuel supply pipe 4. 5
is the igniter.

Water enters the heat exchanger 2 through the water inlet pipe 6, undergoes heat exchange, and is sent to the outlet pipe 7. The inlet pipe 6 has an inlet water flow rate sensor 8
An inlet water temperature sensor 9 is provided, and the hot water outlet pipe 7 is provided with a hot water outlet 10 and a small tank 11 with a small capacity V in the middle. Further, the fuel supply pipe 4 is provided with an opening/closing valve N2.

Reference numeral 13 denotes a controller with a built-in microcomputer 15, which manually inputs the set temperature information from the outlet hot water temperature setting device 14, and manually inputs the input water flow rate information from the water input flow rate sensor 8 and the input water temperature information from the input water temperature sensor 9. A necessary opening/closing operation signal for the opening/closing valve 12 is output. The feedforward control by the :1 controller 13 will be explained in more detail with reference to the flowchart of FIG. 2 and FIG. 3.

When the hot water tap 10 is opened and hot water supply starts, the amount of water input from the water flow rate sensor 8, the temperature of water input manually from the water temperature sensor 9, and the hot water temperature setting 51;
The set hot water temperature set by t and i are read into the microcomputer 15 (a), and first the required amount of heat 61 per unit time (for example, per second) is calculated (
mouth). Then, a pre-stored combustion on time is selected from the calculated required heat IG and the water flow ff1q (c). An example of how to determine the combustion on time can be explained with reference to Fig. 3.
The entire area in the figure is divided into areas A, B, and C, and the combustion on time T is constant for each area. Give 8.

In region A, the required heat Nc I is small, so the combustion on time T is short. ,=S is given. By setting the combustion on time to a short time, instantaneous boiling is prevented, and fluctuations in the hot water temperature are suppressed to improve the hot water tap characteristics. Of course, this time S is not so short as to cause adverse effects on the ignition operation, such as generation of soot and the like.

Next, in region B, the required amount of heat G1 is large, so even if the combustion on time is longer than in the Δ region, the hot water tapping characteristics will not deteriorate so much, so the medium combustion on time T
. Give N=M.

In addition, in region C, the amount of water input is neither very large nor small, and the required heat IC is relatively large, so the hot water output characteristics do not deteriorate so much, and there is little worry of boiling, so it is the maximum usage region of hot water supply. Considering that, in order to give priority to the life, the combustion on time is increased and To,=L
Grant.

Needless to say, the combustion on-times S, M, and L are avoided from extreme values that would cause instantaneous boiling or impede ignition operation in these regions.

Furthermore, the actual values of the combustion on-times S, M, and L vary depending on the water supply capacity of the water heater and the capacity of the burner, for example, from a short time such as several seconds to a long time such as several tens of seconds or even several minutes in some cases. It can be determined within the range of.

In addition, in the above example, the area is divided into three areas A, B, and C, and the combustion on time is set to three areas, S, M, and L. Of course, it is also possible to divide the combustion on time into narrower sections.

The combustion on time T is determined by the above. If N is selected, this combustion on time T. Combustion off time T is determined from N, the calculated required heat FI Gl per unit time, and the combustion heat Mco per unit time (for example, per second) of the burner 3 of the water heater. FF is calculated (2). To explain this calculation method in detail, for example, Gl: co
= 1 : 2”””−・−・・・(1) G1:
If the required amount of heat per unit time Go2 is the amount of combustion heat of the burner per unit time, then the combustion on time of the burner is T. , 4 and combustion off time T. ) F ratio is ToN: TOFF= 1 : 1 -・----(2
)And it is sufficient.

Therefore, the combustion on time T of the burner. If N is selected as, for example, 3 seconds, then the combustion off time T. FF is also calculated as 3 seconds. By setting the combustion on time and combustion off time in this way, it is possible to provide the necessary amount of heat for each cycle.

Combustion on time T is determined as above. , 4 and combustion off time T
. Once F is determined, combustion is started according to that condition (e). That is, the combustion on time T within the controller 13. N and combustion off time T. FF is set, the on-off valve 12 is opened and closed at each set time, and combustion on and combustion off are repeated (f), (f), (f).

Then, when the set hot water temperature is changed, or when the incoming water temperature or incoming water flow rate changes, the combustion on time and combustion off time are newly set.

Effects> The present invention has the above-described configuration, and in an on-off combustion control device using feedforward control in a water heater,
When determining the combustion on time and the combustion off time, a suitable combustion on time, which is recorded in advance, is first selected based on the required heat amount and the flow rate of water input, and the combustion off time is calculated based on this. So simply the desired 11
Not only can hot water be dispensed at M degree, but also hot water can be dispensed with sufficient consideration given to the characteristics of the water heater. In other words, the suitable combustion on time is selected in advance according to the burner capacity, water input flow rate, and required heating V, so that there is no possibility of instantaneous boiling. Such boiling can be reliably prevented even in this area. Of course, extreme on/off values that would generate soot or make ignition difficult are avoided. Furthermore, even in a region where fluctuations in hot water temperature tend to be large, a suitable combustion on time that can reduce fluctuations can be selected, so that the hot water tap characteristics of an instantaneous water heater can be maintained particularly well. Furthermore, in areas where the water heater is frequently used, the combustion on time can be selected to reduce the number of on/off cycles, thereby extending the life of the water heater.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of the implementation device of the present invention, Fig. 2 is a flowchart of on/off combustion control by the controller, and Fig. 3 is a flowchart of on/off combustion control by the controller.
The figure is a diagram showing an example of the combustion on time using the inflow water flow rate and the required amount of heat as parameters. 1: Combustion can body 2: Heat exchanger 3: Burner 8: Incoming water flow rate sensor 9: Incoming water temperature sensor 13: Controller 14: Outgoing hot water temperature setting device 15: Microcomputer

Claims (1)

[Claims] This is an on/off combustion control device for a water heater that burns fuel and uses the generated heat to instantaneously heat water passing through a heat exchanger to supply hot water, and includes an inlet water temperature sensor, an inlet water flow rate sensor,
The heat exchanger has a hot water outlet temperature setting device and a controller with a built-in microcomputer, and the microcomputer is pre-stored with a suitable combustion on time using the input water flow rate and required heat amount per unit time as parameters, and the heat exchanger The required amount of heat per unit time is calculated from the actual water inlet temperature and flow rate, and the set outlet temperature, and the suitable combustion-on time is selected from the required amount of heat and the actual water inlet flow rate. Turning on/off of a water heater characterized in that the combustion off time is calculated from the on time, the required heat amount per unit time, and the combustion heat amount of the burner per unit time, and repeated on/off combustion is performed by feedforward control. Combustion control device.