JPH1151481A - Hot water feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a hot water feeding device at low cost which may prevent both draining and boiling without damaging a stable hot water discharging performance. SOLUTION: In the case that a detected temperature of an outlet temperature sensor is lower than a drain limit temperature (46 deg.C) or in the case that the detected temperature exceeds a boiling limit temperature (85 deg.C), an amount of combustion at a burner is corrected and controlled in such a way that the temperature is kept within a range not less than the drain limit temperature (46 deg.C) and not more than the boiling limit temperature (85 deg.C). This correction control is carried out in preference to a controlling of temperature of discharged hot water to cause the temperature of hot water at a heat exchanger to be kept in a range capable of preventing draining and boiling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater, and more particularly to a water heater of a bypass mixing type.

[0002]

2. Description of the Related Art A water heater provided with a bypass for bypassing a heat exchanger is conventionally known. In such a water heater, an actuator for changing a bypass flow rate, such as an electromagnetic valve or a water motor, is provided in a bypass passage, and a controller controls and drives the actuator in accordance with a set temperature to change a bypass ratio, so that heat exchange is performed. The temperature of the hot water in the vessel was adjusted so as not to cause drainage or boiling.

[0003]

However, when the drive of the actuator is controlled by the controller as described above, the structure becomes complicated, and it is necessary to separately provide a control circuit for controlling the opening and closing and the drive of the actuator. There is a problem that this leads to an increase in cost. Therefore, it is conceivable to provide a heat responsive member that operates in accordance with a change in hot water temperature in the hot water path and directly change the bypass ratio by the operation. Hot water again)
In such cases, the operation is excessive, and the tapping temperature becomes hunting and unstable. An object of the present invention is to solve the above-mentioned problems and realize a low-cost water heater that prevents drain and boiling without deteriorating stable tapping performance.

[0004]

A water heater according to the present invention, which solves the above-mentioned problems, comprises a heat exchanger for heating water supplied from a water supply passage by a combustion heat of a burner and sending the water to a tap water passage, and the heat exchanger. A bypass path for bypassing the water supply path and the tapping path, a temperature setting means for setting a set temperature, and a tapping temperature control for adjusting a combustion amount of the burner so that the tapping temperature approaches the set temperature. Means for changing the bypass rate by a heat responsive member that operates in response to a change in incoming water temperature,
If the temperature of the hot water in the heat exchanger exceeds a range between a predetermined drain limit temperature and a predetermined boiling limit temperature or lower, a correction control means for correcting and controlling the combustion amount of the burner so as to return to within the range. The gist is to have

[0005] In the water heater of the present invention having the above structure, a part of the water supplied from the water supply channel is branched into the bypass channel, and the hot water heated by the heat exchanger is re-joined and discharged. And
The burner combustion amount is adjusted so that the hot water temperature approaches the set temperature. In addition, the bypass ratio is changed by a heat responsive member that operates according to a change in the incoming water temperature. For example, the hot water temperature in the heat exchanger is maintained at a temperature at which drain and boiling hardly occur by increasing the bypass ratio as the incoming water temperature increases and decreasing the bypass ratio as the incoming water temperature decreases. If the outlet temperature of the heat exchanger exceeds the range between the predetermined drain limit temperature and the predetermined boiling limit temperature despite changing the bypass ratio, the burner is returned to the range. By correcting and controlling the amount of combustion of the fuel, the generation of drain and boiling is reliably prevented.

[0006]

BEST MODE FOR CARRYING OUT 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 one embodiment of the present invention. The water heater includes a heat exchanger 30 to which the water supply channel 10 and the hot water channel 20 are connected,
Burner 40 for heating water flowing through heat exchanger 30
, A bypass path 50 for bypassing the heat exchanger 30 and a controller 60 for controlling combustion. On the upstream side of the branch A of the water supply passage 10 with the bypass passage 50, an incoming water temperature sensor 11 for detecting the incoming water temperature, a water governor 12 for limiting the maximum value of the incoming water flow, and a flow for detecting the incoming water flow. A sensor 13 is provided. An outlet temperature sensor 21 for detecting the temperature of hot water at the outlet of the heat exchanger 30 is provided upstream of the junction B of the hot water outlet 20 with the bypass 50, and is provided downstream of the junction B with the bypass 50. On the side, a tapping temperature sensor 22 for detecting the tapping temperature after mixing is provided. Further, the bypass passage 50 is provided with a bypass valve 70 for adjusting the opening degree of the passage. The gas supply path 80 for supplying gas to the burner 40 is provided with a main solenoid valve 81 for opening and closing the flow path, a main solenoid valve 82, and a proportional valve 83 for adjusting the gas supply amount.

The controller 60 includes a CPU, a RAM, and a ROM that constitute a well-known arithmetic and logic operation circuit (not shown).
It comprises an input interface for inputting signals from various sensors, an output interface for outputting drive signals to various actuators, and the like. The controller 60 is connected to a remote controller 90 having operation switches for performing external operations such as setting of a set temperature and a display for displaying the set temperature and the like.

In the remote controller 90, 38 to 46, 48, 5
The set temperature can be set within a temperature range of 0, 55, and 60 ° C. The controller 60 calculates and controls the amount of heat required to set the tap water temperature to the set temperature based on the set temperature set by the remote controller 90, the detected temperature of the incoming water temperature sensor 11, and the detected flow rate of the flow rate sensor 13. The forward control and the feedback control for correcting the feedforward control amount based on the deviation between the detected temperature of the hot water temperature sensor 22 and the set temperature adjust the opening degree of the proportional valve 83 to control the combustion amount of the burner 40. Is performed.

The bypass valve 70 is provided with a valve body 72 provided in a valve chamber 71 connected in series with the bypass passage 50. The bypass valve 70 has a shape in which a spring load changes in accordance with the incoming water temperature to urge the valve body 72 in the opening direction. A coil spring (hereinafter referred to as an SMA spring) 73 made of a memory alloy, and a bias spring 7 for urging the valve body 72 in a closing direction against a urging force of the SMA spring 73 with a constant spring load.
4 With such a configuration, the SMA spring 73
At a position where the biasing force of the spring and the bias spring 74 are balanced.
2 moves to adjust the opening. The SMA spring 73 has the property of increasing its spring load when the incoming water temperature increases, and decreasing its spring load when the incoming water temperature decreases. Therefore, the opening degree increases as the incoming water temperature increases, and the bypass ratio (bypass to the supply flow rate to the appliance) increases. Flow rate).

Next, the relationship between the incoming water temperature and the bypass ratio will be described with reference to the graph of FIG. In the present embodiment, the drain limit temperature, which is a limit temperature for preventing drain generation in the heat exchanger 30, is 46 ° C., and the boiling limit temperature, which is a limit temperature for preventing boiling in the heat exchanger 30, is 46 ° C. 8
The explanation is made at 5 ° C.

In this graph, a curve a represents a minimum bypass rate at which the hot water temperature in the heat exchanger 30 can be maintained at the drain limit temperature (46 ° C.) or more when the hot water is set at the minimum temperature (38 ° C.). It is a drain limit line showing a value. Curve b represents the maximum value of the bypass ratio at which the hot water temperature in the heat exchanger 30 can be suppressed to the boiling limit temperature (85 ° C.) or less when the hot water is set at the maximum temperature (60 ° C.). Line. Curve c is a control line representing the bypass ratio that the bypass valve 70 changes with respect to the incoming water temperature. In this embodiment, the control line (curve c) is set higher than the drain limit line (curve a) to maintain the hot water temperature in the heat exchanger 30 at or above the drain limit temperature (46 ° C.) regardless of the set temperature. Similarly, by setting the temperature lower than the boiling limit line (curve b), the heat exchanger 3 can be operated regardless of the set temperature.
The temperature of the hot water at 0 is kept below the boiling limit temperature (85 ° C.). That is, by keeping the bypass ratio in a range higher than the drain limit line (curve a) and lower than the boiling limit line (curve b) (hereinafter referred to as a good range), both drain and boiling are performed regardless of the set temperature. It can be prevented.

In this embodiment, the minimum set temperature is set to 38 ° C. and the maximum set temperature is set to 60 ° C. When the maximum set temperature is set to, for example, 70 ° C., the boiling limit line is set as shown by a curve d. Is at a position lower than the boiling limit line (curve b) at the maximum temperature of 60 ° C., and there is no water inlet temperature that can prevent both draining and boiling. That is, in this embodiment, the maximum temperature and the minimum temperature of the set temperature are limited so that the range of the incoming water temperature where the good region exists can be widened.

[0013] As described above, the good temperature range is established by limiting the set temperature to 38 to 60 ° C.
Since the drain limit line (curve a) and the boiling limit line (curve b) intersect at about 7.6 ° C., there is no good range in the range where the incoming water temperature is higher than this intersection, and the drain is independent of the set temperature. There is no bypass ratio that can prevent both boiling and boiling. Actually, there is an error in the control amount of the bypass ratio due to the variation of the spring load of the SMA spring 73 and the bias spring 74, the variation of the valve body 72, and the like. The incoming water temperature range where the good region exists is 25 ° C. or less. The maximum temperature may be lowered or the minimum temperature may be increased to widen the water inlet temperature range where the good region exists. However, the narrower the set temperature range is, the more the usability is impaired. It is desirable. Therefore, the temperature detected by the outlet temperature sensor 21 is changed to the drain limit temperature (4
When the temperature is below the boiling limit temperature (85 ° C.) or below the boiling limit temperature (85 ° C.), the burner 4 is controlled to maintain the temperature within the range from the drain limit temperature (46 ° C.) to the boiling limit temperature (85 ° C.).
Correction control is performed for the combustion amount of 0. By performing this correction control prior to the hot water temperature control, the hot water temperature in the heat exchanger 30 is maintained in a range where drain and boiling can be prevented.

Although the drainage and the boiling can be prevented by such correction control, a temperature difference is generated between the set temperature and the tapping temperature by the amount of combustion corrected. Here, the temperature difference generated when the incoming water temperature is 30 ° C. will be described. When the bypass ratio is 45.5% due to the variation of the bypass valve 70, the temperature becomes lower than the drain limit line (curve a). Therefore, the tapping temperature is set to the set temperature at the minimum temperature (38 ° C.). , The hot water temperature in the heat exchanger 30 falls below the drain limit temperature (46 ° C.). Therefore, the amount of combustion is corrected and controlled so that the temperature detected by the outlet temperature sensor 21 does not fall below the drain limit temperature (46 ° C.). At this time, the tapping temperature is (1−0.455) × 46 + 0.455 × 30. = 38.
72 [° C.], which is only 0.72 ° C. higher than the set temperature. That is, when the water temperature is in the range of 30 ° C. or lower, the tapping temperature is set to 38-38.
Since the temperature can be controlled within 72 ° C., the usability is not impaired.

When the bypass ratio is 50% due to the variation of the bypass valve 70, it becomes higher than the boiling limit (curve b), so that the set temperature is the maximum temperature (60 ° C.).
If it is attempted to control the tapping temperature to the set temperature in a state where the temperature is set to, the hot water temperature in the heat exchanger 30 becomes the boiling limit temperature (85
° C). Therefore, the amount of combustion is corrected and controlled so that the temperature detected by the outlet temperature sensor 21 does not exceed the boiling limit temperature (85 ° C.). The tapping temperature at this time is (1−0.5) × 85 + 0.5 × 30. = 57.5 [° C.], which is 2.5 ° C. lower than the set temperature. That is, when the water temperature is 30 ° C. or lower, the set temperature is set to the maximum temperature (60 ° C.).
° C), the tapping temperature can be controlled between 57.5 and 60 ° C. Considering that the temperature is not the temperature at which the user directly touches the hot water, such a temperature difference hardly hinders.

As described above, according to the water heater of the present embodiment, the hot water temperature in the heat exchanger 30 is reduced to a temperature at which drain and boiling hardly occur by changing the bypass ratio according to the incoming water temperature. Can be kept. In addition, when the temperature detected by the outlet temperature sensor 21 falls below the drain limit temperature (46 ° C.) or exceeds the boiling limit temperature (85 ° C.), the boiling limit temperature (85 ° C.) or higher is reached.
[Deg.] C) Since the combustion amount of the burner 40 is corrected and controlled so as to keep it within the range below, drain and boiling can be prevented irrespective of the set temperature and the incoming water temperature. Further, by suppressing the maximum temperature of the set temperature to 60 ° C., the water inlet temperature range where the good region exists is widened, and the bypass valve 70 maintains the bypass ratio with respect to the water inlet temperature in the good region, so that the water inlet temperature becomes 2 °.
If the temperature is 5 ° C or less, drainage and boiling can be prevented while hot water at the set temperature is being discharged. Even in rare cases where the incoming water temperature is higher than 25 ° C, the set temperature is set near the minimum temperature or near the maximum temperature. The tapping temperature only slightly increases or decreases in the state in which the hot water is kept, and the usability is not impaired. As described above, in the present embodiment, the maximum temperature is suppressed to 60 ° C. in order to widen the temperature range of the incoming water in which the good region exists. However, actually, hot water is required only when hot water is supplied. Therefore, it is desired to lower the maximum temperature to some extent from the viewpoint of safety. Particularly, since a water heater provided with a reheating circuit that circulates and reheats the hot water in the bathtub has been used recently, it does not matter even if the temperature is not set so high. In addition, there are cases where the maximum temperature is limited to 55 ° C. for safety reasons in foreign countries. From such a background, it can be said that the set temperature range of 38 to 60 ° C. is sufficient.

Further, the configuration in which the bypass ratio is changed according to the incoming water temperature makes it possible to stabilize the tapping temperature as compared with the configuration in which the bypass ratio is changed according to the tapping temperature. In addition, the configuration in which the SMA spring 73 is directly operated according to the incoming water temperature can be realized at low cost.

In this embodiment, the SMA spring 73 is used as the heat responsive member of the bypass valve. However, the present invention is not limited to this, and any SMA spring can be used as long as it operates according to a temperature change. Further, in the present embodiment, in the range where the incoming water temperature is 25 ° C. or lower, draining and boiling can be prevented even when tapping is performed at the set temperature. However, the present invention is not limited to this. May be set.

The embodiments of the present invention have been described above.
The present invention is not limited to these embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

[0020]

As described above in detail, according to the water heater of the present invention, the hot water temperature in the heat exchanger is changed by changing the bypass ratio by the heat responsive member which operates according to the change of the incoming water temperature. It is possible to maintain a temperature at which drain and boiling hardly occur. Further, since the bypass ratio is changed according to the change in the incoming water temperature, the tapping temperature can be stabilized as compared with a configuration in which the bypass ratio is changed according to the change in the tapping temperature. Further, since the heat responsive member is directly operated by the change of the incoming water temperature, it is not necessary to separately control the heat responsive member, and the structure can be simplified and realized at low cost. In addition, when the temperature of the hot water in the heat exchanger exceeds the range between the drain limit temperature and the boiling limit temperature, the burner combustion amount is corrected and controlled so as to return the temperature within the range. Occurrence can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a water heater as one embodiment.

FIG. 2 is a graph showing a relationship between an incoming water temperature and a bypass ratio.

[Explanation of symbols]

10 ... water supply channel, 20 ... hot water channel, 30 ... heat exchanger,
40 burner, 50 bypass path, 60 controller, 70 bypass valve, 71 valve chamber, 72 valve body,
73 ... SMA spring, 74 ... Bias spring, 90 ... Remote control.

Claims (1)

[Claims] 1. A heat exchanger that heats water supplied from a water supply channel by combustion heat of a burner and sends the water to a hot water channel, and a bypass that bypasses the heat exchanger and communicates the water channel with the hot water channel. A water setting device for setting a set temperature, and a hot water temperature control device for adjusting a combustion amount of the burner so that the hot water temperature approaches the set temperature. A bypass ratio changing means for changing a bypass ratio by an operating heat responsive member; and, if the temperature of the hot water in the heat exchanger exceeds a range of not less than a predetermined drain limit temperature and not more than a predetermined boiling limit temperature, the range is set. And a correction control means for correcting and controlling the amount of combustion of the burner so as to return the burner to the inside.