JPH0712740U - Water heater - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a fast rise in hot water temperature at the start of hot water. [Composition] For a predetermined time immediately after the end of the slow ignition, the upper limit of the opening of the proportional control valve is set to an opening exceeding the maximum number specified in the appliance (S13), and the maximum number is dealt with after the elapse of the predetermined time. It returns to the opened degree (S15).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a water heater that heats water passing through a heat exchanger with a burner to discharge hot water.

[0002]

[Prior art]

 Conventionally, in this type of water heater, the opening of the proportional control valve is controlled to adjust the amount of fuel gas so that the hot water outlet temperature reaches a desired set temperature. Generally, such temperature control includes feed back control such as PID control and PD control based on the hot water temperature detected by a temperature sensor provided on the outlet side of the heat exchanger and the set temperature arbitrarily set by the user. Also known is feedforward control that calculates the amount of fuel gas for heating to a set temperature based on the incoming water temperature and the incoming water amount. In such a water heater, the burner is ignited to heat the heat exchanger after the hot water tap is opened and water flow is detected, so from the start of this water flow until the temperature of the hot water actually discharged reaches the set temperature. Takes some time. For this reason, there was a demand for a quick rise in the hot water temperature at the start of hot water. At the time of ignition, in order to prevent explosive ignition, a slow ignition operation that suppresses combustion capacity is executed for a short period before entering the hot water temperature control.

[0003]

[Problems to be solved by the device]

 However, even if hot water temperature control is performed by the above-mentioned feedback control, etc., the burner combustion amount (proportion of the proportional valve) is limited to the maximum number specified for the appliance, so the water flow rate and maximum The rising characteristics of the hot water temperature are determined by the number of issues. For this reason, even if full-power burning is performed with the maximum number specified for the equipment by controlling the tapping temperature, the tapping characteristics are poor. Therefore, the rising characteristics of the hot water temperature cannot be further improved. By the way, although the heat exchanger, burner, combustion chamber, etc. that make up the combustor are designed according to the maximum number specified in the equipment, there is some margin in terms of durability. For example, it is designed so that even if the No. 16 water heater is burned with the No. 20 capacity, no problem will occur in terms of durability for a short period of time. The present invention focuses on the fact that combustion above the maximum number is possible for a short period of time, and an object thereof is to obtain a fast rise of the tapping temperature at the start of tapping.

[0004]

[Means for Solving the Problems]

 The water heater of the present invention which solves the above-mentioned problems includes a burner for heating water to be passed through a heat exchanger, a regulating valve for adjusting a fuel supply amount to the burner, and a combustion heater for starting combustion heating. In addition, a slow ignition means for igniting while suppressing the fuel supply amount, and a hot water temperature control means for controlling the regulating valve so that the temperature of the hot water passing through the heat exchanger reaches a set temperature after the slow ignition is completed. In the provided water heater, the hot water outlet temperature control means sets the upper limit of the opening degree of the regulating valve to an opening degree exceeding the maximum number specified in the appliance immediately after the slow ignition is finished, and after a predetermined period of time has elapsed. The gist is that an opening upper limit changing means for returning the opening upper limit of the adjusting valve to the opening corresponding to the maximum number is provided.

[0005]

[Action]

 In the water heater of the present invention having the above-described configuration, at the start of hot water discharge, that is, at the start of combustion, the slow ignition means ignites with a reduced fuel supply amount to the burner, and after the slow ignition ends, the hot water temperature control means controls the temperature. enter. In this case, the opening upper limit changing means sets the opening upper limit of the adjusting valve to an opening exceeding the maximum number specified in the instrument. Therefore, even though the amount of water flow corresponds to the number of appliances, the maximum combustion capacity exceeds the number of appliances, so the heating rate becomes faster and the hot water temperature reaches the set temperature in a short time after the start of combustion. Then, after the elapse of a predetermined period, the upper limit of the opening of the adjusting valve is returned to the opening corresponding to the maximum number. That is, the conventional temperature control is performed within the maximum number range. As a result, there is no problem with the durability of the water heater, and the rising temperature of the hot water discharge can be accelerated.

[0006]

【Example】

 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 1 as one embodiment. The water heater 1 includes a water supply pipe 2 connected to the water supply, a heat exchanger 3 for heating the cold water guided by the water supply pipe 2 by the combustion heat of the burner 10, and a hot water heated by the heat exchanger 3. The hot water supply pipe 4 for sending out constitutes a water flow path in the equipment. The water supply pipe 2 is provided with a water governor 5 for maintaining a predetermined flow rate regardless of fluctuations in the water supply pressure, and a water flow switch 6 for detecting the presence or absence of water flow on the downstream side thereof. On the other hand, the hot water supply pipe 4 is provided with a thermistor 7 for detecting the hot water discharge temperature at the outlet of the heat exchanger 3, and an external pipe 9 leading to a hot water tap 8 of a kitchen or the like is connected to the connection port at the tip. To be done.

The gas conduit 11 leading to the burner 10 is provided with an original solenoid valve 12 that controls the opening and closing of the gas flow path from its upstream side, and a proportional control valve 13 that adjusts the gas flow rate. Further, although not shown, an ignition electrode of the burner 10, an igniter, a flame detecting rod, a fan for forcibly supplying combustion air to the combustion chamber, and the like are provided.

A controller 20 is provided in the appliance to control the operation of the water heater. The controller 20 is mainly configured by a microcomputer that constitutes a well-known arithmetic and logic operation circuit, receives signals from sensors such as the water flow switch 6, thermistor 7, frame rod, etc., and also controls the main solenoid valve 12 and proportional control. Drive control signals are output to actuators such as the valve 13, igniter, and fan.

Next, the hot water supply control will be described. The water heater according to the present embodiment will be described as having a No. 16 specification. FIG. 2 shows a hot water supply control routine executed by the controller 20, which is started when the hot water tap 8 is opened and the water flow switch 6 is turned on.

When the control routine is started, first, the fan is driven to perform the pre-purge process (S10), and then the slow ignition process is performed (S11). In this slow ignition process, the ignition operation is performed by narrowing the opening of the proportional control valve 13 in order to avoid explosive ignition. In other words, the main solenoid valve 12 is energized and opened, and a current for slow ignition is passed through the proportional control valve 13 to operate the igniter with a small gas supply amount (input) to ignite. When the flame is detected by the slow ignition in this way, the igniter is stopped and the comparative temperature control is started as follows.

First, it is determined whether or not a predetermined time (30 seconds in the present embodiment) has elapsed after entering the proportional temperature control (S12). In this case, since it is immediately after the end of the slow ignition, it is determined to be "NO", and the maximum capacity (upper limit input) used in the proportional temperature control is set to be equivalent to No. 20 (S13). In other words, since the water heater of the present embodiment is the No. 16 specification, the maximum capacity is essentially No. 16, but when the proportional temperature control is started from slow ignition, the upper limit is the input equivalent to No. 20, which exceeds this upper limit. Set. Then, based on the hot water discharge temperature obtained from the thermistor 7 and the preset temperature, the opening degree of the proportional control valve 13 is controlled so that the hot water discharge temperature becomes the preset temperature (S14). In the present embodiment, PID control is performed based on the deviation between the hot water temperature and the set temperature, the deviation change rate, and the accumulated deviation value. In order to obtain the optimum air-fuel ratio, the fan rotation speed will also depend on the input.

In this case, since the water flow amount is regulated to the 16th specification by the water governor 5, the input can be made larger than the water flow amount, and the rising temperature of the hot water discharge can be accelerated. FIG. 3 is a graph showing the change in the internal pressure of the air-fuel mixture (the square root of the internal pressure is proportional to the gas supply amount) and the outlet temperature at the start of tapping, in comparison with the conventional one (shown by the broken line). As shown in the figure, the PID control is started from the time A when the slow ignition ends, but the upper limit of the opening of the proportional control valve 13 is set to the equivalent of No. 20, so the opening of the proportional control valve 13 is set to No. 16. If the hot water temperature is still lower than the set temperature even after reaching a considerable amount, the opening temperature is controlled to increase and the hot water temperature rises quickly. On the other hand, in the conventional type, when the opening of the proportional control valve 13 reaches No. 16, the opening cannot be exceeded even if the outlet temperature is low, so the outlet temperature rises slowly and reaches the set temperature. It takes time to become. According to JIS, the time required to raise the temperature to 90% of the temperature difference between the incoming water temperature and the set temperature is called the heating rate. Compared with the conventional heating rate, there is a considerable difference (Δt) as shown in the figure. Out.

The change in the hot water discharge temperature shown in this graph is the temperature change captured at the outlet of the hot water supply pipe 4 in the appliance, and there is a portion X that exceeds the set temperature at the start of hot water discharge. The actual temperature change discharged from the hot water tap 8 is smooth as shown by the alternate long and short dash line in Fig. 4 and no problem occurs (Fig. 4 shows an example in which the external pipe is 2 m).

Returning to the description of the hot water supply control of FIG. 2, when the predetermined temperature (30 seconds) has elapsed since the proportional temperature control corresponding to No. 20 has started (S12: YES), the upper limit input in the proportional temperature control is changed to that corresponding to No. 16. Yes (S15). In other words, the original 16 specifications are restored. Therefore, the normal proportional temperature control of the 16th specification is performed thereafter. As a result, the temperature of the hot water rises quickly at the start of hot water discharge without impairing the durability of the equipment, which makes it extremely convenient.

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 scope of the present invention. is there.

[0016]

[Effect of device]

 As described above in detail, according to the hot water supply device of the present invention, when the hot water temperature control is started, the upper limit of the opening degree of the regulating valve is set to an opening degree exceeding the maximum number specified in the appliance. It has the excellent effect that the temperature of the hot water starts up quickly at the start and is extremely convenient.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a hot water supply control routine.

FIG. 3 is a graph showing changes in tapping temperature and internal pressure.

FIG. 4 is a graph showing a transition between a hot water outlet temperature at an appliance outlet and a hot water outlet temperature at a hot water tap.

[Explanation of symbols]

1 ... Water heater, 3 ... Heat exchanger, 7 ... Thermistor, 1
0 ... Burner, 13 ... Proportional control valve, 20 ... Controller.

Claims (1)

[Scope of utility model registration request] 1. A burner for heating water flowing through a heat exchanger, a regulating valve for adjusting a fuel supply amount to the burner, and a fuel supply amount to be suppressed when combustion heating is started by the burner. In a hot water supply device comprising: a slow ignition means for igniting the hot water, and a hot water temperature control means for controlling the adjusting valve so that the temperature of the hot water passing through the heat exchanger reaches a set temperature after the slow ignition is finished. Hot water temperature control means, immediately after the end of the slow ignition,
An opening that sets the upper limit of the opening of the adjusting valve to an opening exceeding the maximum number specified in the instrument, and returns the opening upper limit of the adjusting valve to the opening corresponding to the maximum number after a lapse of a predetermined period. A water heater having an upper limit changing means.