JP3769660B2 - Water heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water heater that controls the temperature of a hot water by adjusting the combustion amount of a burner.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known a water heater that heats supplied water with combustion heat of a burner to discharge hot water. In general, such a water heater is provided with a proportional valve that adjusts the gas supply amount to the burner, and performs hot water temperature control that adjusts the combustion amount of the burner to bring the hot water temperature close to the set temperature. In addition, the maximum burn amount of the burner is determined in consideration of the durability of the device and the burnability of the burner, and the maximum capacity of the device is determined by the maximum amount of combustion. For example, when there is an ability to discharge 16 liters of hot water at 25 ° C. higher than the incoming water temperature, the capacity is classified as No. 16. The burner maximum combustion amount is limited by the maximum opening of the proportional valve.
[0003]
[Problems to be solved by the invention]
However, even if the opening degree of the proportional valve is the same, the burner combustion amount may be different. For example, in city gas, there is a variation in the Wobbe index (the value obtained by dividing the calorific value of the gas by the square root of the specific gravity of the gas), and even if the proportional valve opening is the same, if the Wobbe index is large, the burner is proportionally generated. The amount of heat increases. Similarly, in the LP gas, the butane content varies, and the higher the butane content, the greater the amount of heat generated by the burner. In addition, even when the Wobbe index is low, the pressure loss in the gas passage increases and the governor characteristic jumps up, and the amount of heat generated by the burner may increase. Therefore, when the capacity is exceeded (the amount of heat necessary to raise the temperature of the water to the set temperature exceeds the maximum amount of heat generated by the burner), the proportional valve opening is maximum, so the Wobbe index is large, etc. In such a case, there is a problem that the burner burn amount exceeds the maximum burn amount and the combustion state, durability, and the like deteriorate. Therefore, in practice, it is necessary to provide a sufficient flammability and durability. For example, the maximum capacity must be used as No. 16 in spite of the equipment that can use the maximum capacity as No. 18.
[0004]
An object of the present invention is to provide a water heater that solves the above-described problems and that does not exceed the maximum combustion amount of the burner even when the supply gas varies.
[0005]
[Means for Solving the Problems]
The water heater of the present invention that solves the above problems is a heat exchanger that heats the water supplied from the water supply channel by the combustion heat of the burner and supplies it to the hot water supply channel,
A flow rate sensor for detecting a flow rate through the heat exchanger;
An incoming water temperature detecting means for detecting the temperature of the supplied water;
A hot water temperature sensor for detecting the temperature of hot water in the hot water path,
In a water heater provided with a combustion amount adjusting means for adjusting the combustion amount of the burner,
When the heating amount calculated based on the detection value of the flow rate sensor, the detection value of the incoming water temperature detection means, and the detection value of the tapping temperature sensor exceeds a predetermined value, the heating amount is the predetermined value. The gist is to adjust the combustion amount of the burner so as to be less than the value.
[0006]
The hot water heater of the present invention having the above configuration heats the water supplied from the water supply channel with the combustion heat of the burner and discharges the hot water. Here, even when the burner combustion amount exceeds the maximum combustion amount specified for the appliance, the amount of heat used to heat the water is calculated from the incoming water flow rate, incoming water temperature and outgoing hot water temperature, and the calculated value is predetermined. When the value is exceeded, it is determined that the burner combustion amount exceeds the maximum combustion amount, and the combustion amount is adjusted, so that it can be limited to the maximum combustion amount or less. In addition to the method of directly detecting the temperature by providing a temperature sensor in the water supply channel, the incoming water temperature may be calculated back from the hot water temperature, the incoming water flow rate, and the burner combustion amount. You may assume from the detected value of a temperature sensor.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the water heater of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a water heater as an embodiment of the present invention. This water heater includes a heat exchanger 3 to which a water supply channel 1 and a hot water channel 2 are connected, a burner 4 for heating water flowing through the heat exchanger 3, and a gas supply channel 5 for supplying gas to the burner 4. And a controller 6 for controlling the combustion control. The water supply channel 1 is provided with a water governor 7 that adjusts the maximum flow rate according to the incoming water temperature, a flow rate sensor 8 that detects the incoming water flow rate, and an incoming water temperature sensor 9 that detects the incoming water temperature. Is provided with a tapping temperature sensor 10 for detecting tapping temperature, and a hot water tap 11 is connected to the downstream side thereof. Further, the gas supply path 5 is provided with a main electromagnetic valve 12 and an original electromagnetic valve 13 that open and close the flow path, and a proportional valve 14 that adjusts the gas amount.
[0008]
The controller 6 includes a CPU, RAM, and ROM that constitute a well-known arithmetic logic circuit (not shown), an input interface that inputs signals from various sensors, an output interface that outputs drive signals to various actuators, and the like. The controller 6 is connected to a remote controller 15 that includes an operation switch for setting a set temperature.
[0009]
The controller 6 also includes a feed forward control (hereinafter referred to as FF control) for calculating and controlling the amount of gas necessary for setting the hot water temperature to the set temperature based on the set temperature, the incoming water temperature, and the incoming water flow rate; By using feedback control (hereinafter referred to as FB control) for correcting the FF control amount based on the deviation between the temperature and the set temperature, the hot water temperature control is performed by adjusting the opening of the proportional valve.
[0010]
Next, control processing performed by the controller 6 will be described with reference to the flowchart of FIG. When the hot-water tap 11 is opened and water flow to the appliance is started and the flow rate sensor 8 detects a flow rate equal to or higher than a predetermined value (S1: YES), the main solenoid valve 12 and the original solenoid valve 13 are opened and the burner 4 is opened. The gas is supplied to the gas and ignited by an ignition device (not shown) (S2) to start the combustion operation. Further, the FF control based on the product of the difference between the set temperature set by the remote controller 15 and the detected temperature of the incoming water temperature sensor 9 and the detected flow rate of the flow rate sensor 8, the set temperature and the detected temperature of the tapping temperature sensor 10 With the FB control based on the deviation, the opening of the proportional valve 14 is adjusted to control the hot water temperature (S3).
[0011]
During the hot water operation, it is used to heat the water from the product of the difference between the hot water temperature and the incoming water temperature (rising temperature) and the incoming water flow rate in order to determine whether the burner 4 combustion amount does not exceed the maximum combustion amount. The calculated amount of heat is calculated (S4). Further, the controller 6 stores a product of the heat generation amount and the thermal efficiency at a predetermined maximum combustion amount of the burner 4 as a reference value, and compares the reference value with the calculated value, thereby combusting the burner 4. The amount is checked (S5). Here, if the calculated value is equal to or less than the reference value (S5: NO), it is determined that the combustion amount of the burner 4 is equal to or less than the maximum combustion amount. However, when the calculated value exceeds the reference value (S5: YES), if the burned amount of the burner 4 has exceeded the maximum burned amount, for example, because the Wobbe index of the supplied gas is large. The proportional valve opening is adjusted in the closing direction to decrease the supply gas amount (S6), the combustion amount of the burner 4 is decreased, and the adjustment is terminated when the calculated value is less than the reference value (S5: NO).
[0012]
A hot water discharge capacity diagram when the incoming water temperature of this water heater is 15 ° C. is shown in FIG. In this water heater, the maximum flow rate is limited to 8.9 liters / minute by the water governor 7 when the incoming water temperature is 15 ° C. so that the hot water at 60 ° C. can be secured regardless of the incoming water flow rate. Accordingly, when the set temperature is set to 75 ° C. and the hot-water tap 11 is fully opened, as shown by the point a, the combustion amount of the burner 4 is maximized, but the tapping temperature rises only to 60 ° C. Here, when the combustion amount of the burner 4 is increased by 10% due to the situation where the Wobbe index is large or the butane content is high, the tapping temperature rises to 64.4 ° C. as indicated by the point b. Therefore, the burner 4 continues to burn at a combustion amount of 10% up to the maximum combustion amount, so that the burnability of the burner 4 and the durability of the appliance are deteriorated. However, in the water heater of this embodiment, when the amount of heat used for heating the water is calculated from the incoming water temperature, outgoing hot water temperature, and incoming water flow rate, and it is determined that the combustion amount of the burner 4 exceeds the maximum combustion amount. In order to reduce the combustion amount, the combustion amount of the burner 4 can be limited to the maximum combustion amount or less.
[0013]
As described above, according to the water heater of the present embodiment, even if the combustion amount of the burner 4 exceeds the maximum combustion amount for some reason, the difference between the hot water temperature and the incoming water temperature and the incoming water flow rate. The amount of heat used to heat the water is calculated from the product of, and the combustion amount of the burner 4 is checked against the reference value. If the calculated value exceeds the reference value, the gas supply amount is reduced. Since the combustion amount of the burner 4 is limited to the maximum combustion amount or less, the combustion state and durability can be kept good, and there is no need to improve the durability of the appliance and the burnability of the burner excessively. Further, by calculating the combustion amount of the burner 4 using a sensor used for conventional hot water temperature control, it is not necessary to newly use a sensor, so that the cost can be reduced.
[0014]
In this embodiment, the incoming water temperature is detected by the incoming water temperature sensor 9, but without the incoming water temperature sensor 9, it may be calculated back from the outgoing hot water temperature, incoming water flow rate, and proportional valve opening, and the outgoing hot water at the start of the outgoing hot water. The incoming water temperature may be assumed from the temperature detected by the temperature sensor 10 or the temperature change. Further, in this embodiment, the amount of heat used for heating the water calculated from the incoming water temperature, the outgoing hot water temperature and the incoming water flow rate is compared with a reference value which is the product of the generated heat amount and the thermal efficiency at the maximum combustion amount of the burner 4. However, the amount of heat generated by the burner 4 may be calculated by dividing the heat quantity calculated from the incoming water temperature, the outgoing hot water temperature, and the incoming water flow rate by the thermal efficiency, and the generated heat quantity at the maximum combustion amount may be compared as a reference value.
[0015]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.
[0016]
【The invention's effect】
As described in detail above, according to the water heater of the present invention, the burner combustion amount can be limited to the maximum combustion amount or less prescribed in the appliance, so that deterioration in combustibility and durability is prevented. This eliminates the need to improve the durability of the instrument and the burnability of the burner. In addition, by calculating the amount of heat used for heating water using a sensor conventionally used for hot water temperature control, it is not necessary to newly provide a sensor or the like, so that the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a water heater as an embodiment of the present invention.
FIG. 2 is a flowchart showing a control process performed by a controller.
FIG. 3 is a graph showing a hot water discharge capacity range.
[Explanation of symbols]
1 ... water supply channel, 2 ... hot water supply channel, 3 ... heat exchanger, 4 ... burner,
6 ... Controller, 8 ... Flow rate sensor, 9 ... Incoming water temperature sensor,
10 ... Hot water temperature sensor, 11 ... Hot water tap, 14 ... Proportional valve, 15 ... Remote control.

Claims (1)

A heat exchanger for heating the water supplied from the water supply channel with the combustion heat of the burner and supplying it to the hot water supply channel;
A flow rate sensor for detecting a flow rate through the heat exchanger;
An incoming water temperature detecting means for detecting the temperature of the supplied water;
A hot water temperature sensor for detecting the temperature of hot water in the hot water path,
In a water heater provided with a combustion amount adjusting means for adjusting the combustion amount of the burner,
When the heating amount calculated based on the detection value of the flow rate sensor, the detection value of the incoming water temperature detection means, and the detection value of the tapping temperature sensor exceeds a predetermined value, the heating amount is the predetermined value. A hot water heater characterized by adjusting the amount of burner burn so as to be below the value.

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