JP2814004B2 - Gas water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a gas valve that controls the amount of gas supplied to a gas burner by continuously changing the opening of the gas valve. The present invention relates to an instantaneous gas water heater capable of obtaining hot water at a set temperature.

(Prior Art) In this type of gas water heater, as disclosed in, for example, Japanese Utility Model Laid-Open Publication No. 1-136266, there is a problem that when the tapping temperature is set to a high temperature, the tapping temperature decreases when the tapping amount is increased. In order to solve this, if a water governor is provided to limit the flow rate so that the flow rate does not exceed a predetermined value, the flow rate is limited even when the tapping temperature is set to a relatively low temperature such as a shower. Therefore, there is a problem that only a small amount of hot water can be obtained even though the heating capacity has room.

In Japanese Unexamined Utility Model Publication No. 1-136266, in order to solve such a problem, an on-off solenoid valve is provided in a bypass formed in parallel with the water governor, and when the tapping temperature is set to a high temperature, the solenoid valve is closed. When the temperature is set low, the maximum water flow is switched to two levels by opening.

(Problems to be Solved by the Invention) However, such a conventional technique requires an electromagnetic valve in the bypass path and also requires a control circuit therefor, so that the apparatus becomes expensive. In addition, since the maximum water flow rate is switched in two stages, depending on the tapping temperature, only a small amount of tapping water may be obtained despite the remaining heating capacity.
The heating capacity of the gas water heater cannot be used effectively in the entire range of the tapping temperature.

SUMMARY OF THE INVENTION The present invention solves such a problem, and enables the maximum water flow rate to be switched with a simple structure, and the heating capability of the gas water heater to be effectively used in the entire range of the tap water temperature. With the goal.

(Means for Solving the Problems) To this end, the gas water heater according to the present invention includes a heat exchanger 11, a water supply pipe 12 and a hot water supply pipe 13 connected before and after the heat exchanger 11, as illustrated in the accompanying drawings. A gas burner 15 for heating feed water passing through the heat exchanger 11, a proportional control valve 17 for controlling a gas supply amount so that a tapping temperature in the hot water supply pipe 13 becomes a temperature set by a user, A water governor 20 is provided on the pipe 12 to limit the maximum water flow rate.The water governor is provided in series with the casing 21 forming a part of the water supply pipe 12 and the water supply pipe 12 in the casing. A pressure restriction member 34 fitted in the casing 21 and displaced against a spring 36 due to a pressure difference before and after the control restriction 34, and the spring 36 provided on the pressure reception member. Due to the displacement of the casing 21 Variable throttle 38a to reduce the passage area of the serial water supply pipe 12, 38
b comprises a movable valve element 31 formed between the control throttle 34 and the casing downstream of the control throttle 34.
In a gas water heater in which a bypass valve 40 is provided in a bypass passage 28 formed in the casing 21 in parallel with the above, a part of the hot water supply pipe 13 provided in the casing 21 adjacent to the bypass passage 28 is provided. An operating chamber 29 to be formed, a valve rod 43 having one end fixed to the valve body 42 of the bypass valve 40, protruding into the operating chamber 29 through a part of the casing 21 in a liquid-tight and slidable manner, In the working chamber 29, the casing
A heat responsive member 46 interposed between the other end of the valve stem 43 and the other end of the valve stem 43, which is deformed in accordance with the temperature and increases the tapping temperature and reduces the opening of the bypass valve 40 through the valve stem 43. It is characterized by having.

It is desirable that the heat responsive member 46 has a characteristic of being continuously deformed according to the temperature.

(Operation) When the gas water heater is not operated, the temperature in the working chamber 29 is low, so that the bypass valve 40 is fully opened. In operation,
The proportional control valve 17 controls the gas supply amount to the gas burner 15 such that the opening degree automatically changes and the hot water temperature in the hot water supply pipe 13 becomes a temperature set by the user. When the tapping temperature is low, the opening of the bypass valve 40 is set to be large, and when the tapping temperature is high, the opening of the bypass valve 40 is set to be small. Therefore, the maximum flow rate provided by the operation of the water governor 20 is continuously switched so as to be large when the set tapping temperature is low and small when the set tapping temperature is high.

Further, if the heat responsive member 46 has a characteristic of being gradually deformed according to the temperature, the switching of the maximum water flow rate is performed more smoothly and continuously.

(Effects of the Invention) According to the present invention, the maximum water flow rate is continuously switched, so that the heating capacity of the gas water heater can be effectively used in substantially all of the tapping temperature range. Furthermore, since the bypass valve is operated by the heat responsive member provided in the working chamber forming a part of the hot water supply pipe, the structure is simpler than the bypass valve using the solenoid valve, and the control circuit is not required. And the manufacturing cost can be reduced. Also, if the maximum water flow is switched more smoothly by using a heat responsive member that gradually deforms according to the temperature of the heat responsive member, the tapping temperature at which the heating capacity of the gas water heater can be used effectively. The range can be further expanded.

(Examples) The present invention will be described below with reference to examples shown in the attached drawings.

As shown in FIG. 1, a water supply pipe 12 and a hot water supply pipe 13 are provided before and after a heat exchanger 11 provided at an upper portion in an inner body 10 of the instantaneous water heater.
Is connected to the hot water supply pipe 13 and a temperature sensor 19 such as a thermistor.
Is provided. Fuel gas is supplied to a gas burner 15 provided at a lower portion in the inner body 10 and heating water passing through the heat exchanger 11 by a gas supply pipe 16 provided with a proportional control valve 17. The proportional control valve 17 of the present embodiment is an electromagnetic valve whose opening continuously changes, and a hot water supply pipe detected by the temperature sensor 19.
The opening degree is controlled by a controller 18 for inputting the hot water temperature in the hot water supply 13 so that the hot water temperature from the hot water tap 14 at the tip of the hot water supply pipe 13 becomes the temperature set by the user using an operating device (not shown). The opening is controlled.

Next, a description will be given of the water governor 20 provided in the middle of the water supply pipe 12 to determine the maximum water flow through the water supply pipe 12. As shown in FIG. 1, a casing 21 of the water governor 20 has an inlet 22 and an outlet.
23 and connected in series with the water supply pipe 12, the inlet 22 and the outlet 23
An inner hole 24 and a first control chamber 25a are formed therebetween. On both sides of the first control chamber 25a, a second control chamber 25b having a first control opening 26a communicating with the inside of the inner hole 24 and a second control opening 26b.
However, both are formed coaxially with the inner hole 24. A flange-shaped pressure receiving member 30 integrally formed with a movable valve element 31 coaxially is fitted in the inner hole 24 so as to be liquid-tight and slidable through an O-ring 30a, and is interposed between the casing 21 and the pressure-receiving member 30. The first spring 36 and the second spring 37 are urged toward the inlet 22 and are in contact with the retaining ring 27 fitted in the inner hole 24 when no external force is applied. In the present embodiment, the first spring 36 is made of a shape memory alloy, and has such a characteristic that the pressing force increases as the temperature rises.

The movable valve body 31 has two annular projections 32a, 32b formed between the control openings 26a, 26b and variable throttles 38a, 38b whose passage areas are reduced by displacements against the springs 36, 37.
Are formed at intervals in the axial direction. Movable valve body
31 has a through hole 3 communicating the inside of the second control chamber 25b with the inlet 22 side.
3 is formed coaxially, and a communication hole 35 which is orthogonal to the through hole 33 and opens on the outer surface between the pressure receiving member 30 and the annular projection 32a.
Are formed. Mainly communication hole 35 and more entrance
A part of the through hole 33 on the 22 side forms a control throttle 34 for controlling the operation of the pressure receiving member 30 and the movable valve element 31.

Next, the bypass valve 40 that changes the maximum flow rate of the water governor 20 will be described. As shown in FIG.
The pressure receiving member is always irrespective of the displacement of the pressure receiving member 30.
A bypass passage 28 whose both ends are opened before and after 30 and an operation chamber 29 that forms a part of the hot water supply pipe 13 are formed adjacent to the bypass passage 28 in the longitudinal direction. A bypass valve seat 41 is formed coaxially with the bypass passage 28, and a valve rod 43, one end of which is fixed to a valve element 42 that continuously opens and closes the bypass valve seat 41, is connected to the working chamber 29 along the bypass passage 28. The casing extends through the casing 21 through a part of the casing 21 in a liquid-tight and slidable manner into the working chamber 29, and a spring receiver 44 is fixed to the other end. This spring receiver
A bias spring 45 is interposed between the valve stem 43 and the casing 21 on the side opposite to the valve stem 43, and a thermally responsive member 46 is interposed on the valve stem 43 side.

The working chamber 29 is connected in series with the hot water supply pipe 13 via an inlet 29a and an outlet 29b. In this embodiment, the heat responsive member 46
Is a coil spring made of a shape memory alloy. The free length of the coil spring hardly changes at a temperature T2 (see FIG. 2, for example, 60 ° C.). In the following, characteristics are provided such that the free length hardly changes again. As a result, the bypass valve 40 is fully closed when the tap water temperature is equal to or higher than T2,
When the tapping temperature is between T2 and T3, the opening degree changes continuously when the tapping temperature is between T2 and T3.

 Next, the operation of the present embodiment will be described.

First, the operation of the water governor 20 will be described.
The water supplied from the inlet 22 passes through the control throttle 34 and then splits into two, one through the communication hole 35 through the variable throttle 38a, and the other through the through hole 33, the second control chamber 25b and the variable throttle 38b. From the exit 23, go to the heat exchanger 11. On both sides of the pressure receiving member 30,
Due to the water supply through the control throttle 34, a pressure difference corresponding to the flow rate is generated. When the amount of water flow is small, the pressure receiving member 30
However, when the pressure difference increases in accordance with the increase in the water flow, the pressure receiving member 30 and the movable valve body 31
Water pipe 1 that moves against 36, 37 and is located downstream
Since the road area of the variable throttles 38a and 38b provided in 2 is reduced, the water flow does not exceed a predetermined maximum value. As a result, the maximum flow rate when the bypass valve 40 is closed is set. In this embodiment, since the first spring 36 is provided with such a characteristic that the pressing force increases in accordance with the temperature rise, the maximum water flow rate is small when the water supply temperature is low, and high when the water supply temperature is high. It will increase if it becomes. As a result, the maximum flow rate is corrected based on the feedwater temperature.

In the state where the bypass valve 40 is open, a part of the water flow from the water supply pipe 12 to the heat exchanger 11 passes through the bypass valve 40, passes through the variable throttle 38a, and goes to the heat exchanger 11 from the outlet 23.
The pressure difference before and after the pressure receiving member 30 decreases, and the variable throttles 38a, 38b
Of the passage area decreases. Then, as the degree of opening of the bypass valve 40 increases, the rate of decrease in the passage area of the variable throttles 38a, 38b further decreases, so that the maximum flow rate regulated by the water governor 20 also increases. Ie water governor
The maximum flow rate given by 20 is a small value above the tapping temperature T2 at which the bypass valve 40 is fully closed,
It becomes a large value below T3 when 40 is fully open, and the tapping temperature is
It changes continuously between T2 and T3.

In this type of gas water heater, as shown in FIG. 2, the maximum capacity characteristic (proportional control valve 17 opening maximum) X and the minimum capacity characteristic (proportional control valve 17 opening minimum) The operation is performed in the range of Y. For example, when the tapping temperature is set to Ta, when the tapping amount is within Va, the opening degree of the proportional control valve 17 changes according to the tapping amount, and the tapping at the temperature Ta is performed. However, if the amount of hot water exceeds Va, even if the amount of hot water increases, the amount of heating by the gas burner 15 does not increase. Therefore, when the amount of hot water reaches V1, the temperature of the hot water drops to T2.

If the characteristic of the maximum water flow rate (maximum hot water output) of the gas burner 15 with respect to the hot water temperature given by the water governor 20 and the bypass valve 40 in this embodiment is shown in FIG. That is, the maximum water flow rate is the minimum value V1 when the tapping temperature is between T1 (the maximum tapping temperature, for example, 80 ° C.) and T2 (eg, 60 ° C.), and the maximum value V2 when the tapping temperature is equal to or less than T3 (eg, 45 ° C.) During this period, the voltage changes continuously from V1 to V2. Accordingly, when the tapping temperature is set between T1 and T2, the heating capacity of the gas burner 15 can be effectively used to the maximum and the tapping temperature can be set to T2 even when the hot water tap 14 is fully opened.
It does not fall below. When the tapping temperature is set between T2 and T3, the heating capacity of the gas burner 15 can be effectively used to the maximum, and the tapping temperature is maintained at the set temperature even when the hot water tap 14 is fully opened. Hot water temperature
When the temperature is set to T3 or less, the amount of hot water is kept at the maximum value V2 and the heating capacity of the gas burner 15 is not used to the maximum. However, if the value of V2 is appropriately set, practical inconvenience is not felt.

In the above embodiment, the characteristics of the maximum flow rate between the tapping temperatures T2 and T3 are matched with the maximum capacity characteristics X.This is because the characteristics of the shape memory alloy constituting the heat responsive member 46 are appropriately set. Can be substantially realized. The characteristic of the maximum water flow rate in this portion does not need to completely match the maximum capacity characteristic X, and if it is a characteristic that is appropriately approached, there is no problem in practical use.

According to the above-described embodiment, the valve body is provided via the valve rod 43 by the thermally responsive member 45 provided in the working chamber 29 forming a part of the hot water supply pipe 13.
Since the bypass valve 40 is operated by displacing the bypass valve 42, the structure of the bypass valve 40 is simplified, and a control circuit therefor is not required, so that the manufacturing cost can be reduced. Also, between the frequently used temperatures T1 and T3,
The entire heating capacity of the gas water heater can be used effectively.

In the above embodiment, a spring made of a shape memory alloy is used as the heat responsive member 46, but another heat responsive member, for example, a wax type thermostat may be used.

[Brief description of the drawings]

1 and 2 show an embodiment of a gas water heater according to the present invention, wherein FIG. 1 is an overall structural diagram in which main parts are enlarged, and FIG. 2 is a characteristic diagram of a tapping amount and a tapping temperature. Description of the reference numeral 11: heat exchanger, 12: water supply pipe, 13: hot water supply pipe, 15 ...
Gas burner, 17… Proportional control valve, 20… Water governor, 21…
... casing, 28 ... bypass path, 29 ... working chamber, 30 ...
... Pressure receiving member, 31 ... Movable valve element, 34 ... Control throttle, 36 ...
Spring (first spring), 38a, 38b: Variable throttle, 40: Bypass valve, 42: Valve body, 43: Valve stem, 46:
… A thermally responsive member.

Claims (2)

(57) [Claims] 1. A heat exchanger, a water supply pipe and a hot water supply pipe connected before and after the heat exchanger, a gas burner for heating water supplied through the heat exchanger, and a tapping temperature in the hot water supply pipe are set by a user. A proportional control valve that controls a gas supply amount to be a temperature, and a water governor that is provided in the water supply pipe and limits a maximum water flow rate.The water governor includes a casing that forms a part of the water supply pipe. A control restrictor provided in series with the water supply pipe in the casing, a pressure receiving member fitted in the casing and displaced against a spring due to a pressure difference between before and after the control restrictor; A movable valve element formed between a casing and a variable throttle downstream of the control throttle to reduce a passage area of the water supply pipe in the casing due to displacement against the spring provided on a member. In a gas water heater having a bypass valve provided in a bypass passage formed in the casing in parallel with the control throttle, a part of the hot water supply pipe provided in the casing adjacent to the bypass passage. A valve stem protruding into the working chamber through a part of the casing that is connected to the valve body of the bypass valve in a liquid-tight and slidable manner, and the casing in the working chamber. A heat responsive member interposed between the other end of the valve stem and the opening of the bypass valve is reduced through the valve stem when the tapping temperature rises due to deformation according to the temperature. And gas water heater. 2. A gas water heater according to claim 1, wherein said heat responsive member has a characteristic of being continuously deformed according to a temperature.