JP2579078B2 - Water heater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater.

[0002]

2. Description of the Related Art For example, a water heater provided with a heat exchanger using a gas burner and a hot water supply passage passing through the heat exchanger is usually provided with a water governor, a water flow switch or the like at a halfway point of the hot water supply passage. Detecting means is provided, and when water flow is detected by the water flow detecting means, the gas is supplied and ignited to the gas burner in response to the detection of water flow, so that the heat exchanger is operated.

[0003] In this type of water heater, when a malfunction of a water governor, a water flow switch, or the like occurs, the heat exchanger is used even when there is no water flow in the hot water supply path or when only a small amount of water is supplied. Operates, so-called residual fire may occur, and when such residual fire occurs, the water in the hot water supply path will be overheated.

For this reason, in this type of water heater, an overheating prevention device is provided in order to prevent the water in the hot water supply passage from being overheated. When the water becomes extremely hot, the operation of the heat exchanger is forcibly stopped.

However, in such a water heater,
When an afterglow occurs as described above, even if the operation of the heat exchanger is stopped, high-temperature hot water remains in the hot water supply passage in the heat exchanger, and thus, such an afterglow has occurred. Immediately after that, when hot water is passed through the hot water supply channel, there is a risk that hot water, which is unexpected by the user, is continuously supplied to a hot water tap in a kitchen or a bathroom.

In this case, in order to prevent such inconvenience, a hot water temperature sensor and a solenoid valve are provided in the hot water supply path downstream of the heat exchanger, and when the hot water temperature detected by the hot water temperature sensor is high, It is conceivable to close the solenoid valve accordingly.

However, in such a method, after the controller of the water heater receives the signal of the hot water temperature sensor,
Since the operation of closing the solenoid valve is performed, a response delay occurs. Therefore, the amount of high-temperature hot water supplied to a kitchen or a bathroom is somewhat reduced, but the high-temperature hot water is still supplied to some extent. There is a fear.

[0008]

SUMMARY OF THE INVENTION The present invention solves such inconvenience, and when the water in the hot water supply path is heated to a high temperature in the heat exchanger due to an after-fire or the like, the hot water can be reliably supplied. It is an object of the present invention to provide a water heater that can be prevented immediately.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, a water heater according to the present invention is a water heater which supplies hot water through a hot water supply passage passing through a heat exchanger, wherein the water heater is provided downstream of the heat exchanger. A bottomed portion provided in a middle part of the channel, the inside of which is communicated with the upstream side and the downstream side of the middle part of the hot water supply channel through an end opening and a side opening formed at one end and a side portion, respectively. A cylindrical valve case, and an open position that is inserted into the valve case from the end opening side to the bottom side with the outer peripheral surface facing the side opening and communicates between the end opening and the side opening. And a valve body movably provided in the axial direction of the valve case between the end opening and the closed position for blocking between the side opening, and the valve body is thermally deformed in accordance with hot water temperature in the valve case. A valve drive comprising a shape memory alloy engaged with the valve body in the valve case to open and close the valve body The valve body, when in its open position, has an inner periphery closer to an end opening than the side opening of the valve case, and an inner periphery closer to the bottom than the side opening of the valve case. A first gap and a second gap are formed between the end opening and the side opening, and the end opening and the side opening communicate with each other through the first gap. The second gap communicates with the valve body through a through hole formed through the valve body in the axial direction of the valve case, and at the closed position of the valve body, the first and second gaps At the point of contact with the inner peripheral portion of the valve case to close the gaps, thereby shutting off the end opening and the side opening. When the temperature is equal to or higher than a predetermined temperature, a thermal deformation that drives the valve body from the open position to the closed position occurs, One When 該湯 temperature falls below a predetermined temperature, characterized in that it is configured to produce the shape restoration returning the valve body to the open position.

[0010]

According to the water heater of the present invention, at a normal temperature where the temperature of the hot water in the hot water supply path downstream of the heat exchanger is not so high, the valve body is in the open position. The hot water flowing through the hot water supply passage flows through the first gap near the end opening of the valve case between the end opening and the side opening of the valve case at the location of the valve case. It flows through the through hole of the valve body and the second gap near the bottom of the valve case. On the other hand, when the temperature of the hot water in the hot water supply path on the downstream side of the heat exchanger becomes high due to embers, etc., and the temperature of the hot water in the valve case becomes equal to or higher than a predetermined temperature, the valve driving section made of the shape memory alloy The valve body is driven to the closed position by the thermal deformation. At this time, the first and second gaps are closed by the valve body abutting on the inner peripheral portion of the valve case at the first and second gaps, whereby the end of the valve case is closed. The opening and the side opening are shut off, and the hot water supply passage is closed at the first and second gaps of the valve case. Therefore, the hot water on the heat exchanger side is prevented from flowing downstream of the valve element. Since the valve driving section is made of a shape memory alloy, when the temperature of the hot water on the heat exchanger side falls below a predetermined temperature and becomes a normal temperature, the valve returns to its original shape, and the valve body smoothly moves. It is returned to the open position and hot water can be supplied without any trouble.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a water heater, and FIGS. 2 (a) and 2 (b).
3A and 3B are longitudinal sectional views of the thermal responsive valve applied to the water heater in an open state and a closed state, respectively. FIGS. 3A and 3B are open and closed states of other thermal responsive valves applied to the water heater, respectively. FIG.

In FIG. 1, a water heater 1 includes a heat exchanger 4 having a gas burner 3, a hot water supply path 5,
Drainage channel 6 for draining hot water supply channel 5 and heat exchanger 4
And a gas passage 7 for supplying gas to the gas burner 3.

In this case, the gas passage 7 is introduced into the main body case 2 via a gas introduction pipe 8 connected to a gas pipe (not shown) outside the main body case 2. The gas is supplied to the gas burner 3 via a gas amount adjusting mechanism 11 operable via a gas amount adjusting handle 10 mounted on the outer surface of the main body case 2, a gas valve 12, a gas governor 13 and a gas nozzle 14. .

When the gas is supplied to the gas burner 3, the heat exchanger 4 ignites the gas burner 3 by an igniter (not shown). At this time, the combustion of the gas causes the main body of the heat exchanger 4 to burn. The water flowing in the hot water supply path 5 is appropriately heated through the section 15.

The hot water supply path 5 is roughly divided into a piping configuration. In the order from the upstream to the downstream, the hot water supply pipe 16 introduced into the main body case 2 from the outside and the detection of water flow through the hot water supply pipe 16 are provided. The present invention relates to an intermediate water pipe 19 connected via a mechanism 17 and a water flow regulator 18, a heated water pipe 21 connected to the intermediate water pipe 19 via an overpressure relief valve 20, and a heating water pipe 21 according to the present invention. And a lead-out water pipe 23 which is connected to a heat-responsive valve 22 having a shape memory alloy according to the present invention and which is led out of the main body case 2 through a heat-responsive valve 22 (to be described in detail later). The introduction water pipe 16 is connected to a pipe 16 made of a resin material such as vinyl chloride outside the main body case 2.
a to a water pipe (not shown) through
Reference numeral 3 denotes a water supply faucet 2 outside the main body case 2.
4 and shower head 25 with hot water taps 26 and 27, respectively.
Connected through. The heating water pipe 21 is wound around the main body 15 of the heat exchanger 4, and the heat-sensitive responsive valve 22 located at a downstream end thereof (a connection point between the heating water pipe 21 and the outlet water pipe 23). Is disposed downstream of the heat exchanger 4 corresponding to the configuration of the present invention. On the upstream side of the heat exchanger 4, a thermosensitive valve 28 (described later in detail) having a structure different from that of the thermoresponsive valve 22 is provided in the middle of the intermediate water pipe 19.

In this case, the water flow detecting mechanism 17 has a well-known water governor 29 and a diaphragm 30.
As is well known, the flow of water in the hot water supply passage 5 is detected based on the water pressure received by the diaphragm 30, and the gas valve 12 of the gas passage 7 is opened and closed via a water governor 29 in response thereto.

The water flow regulator 18 can be operated by a water flow adjustment handle 31 mounted on the outer surface of the main body case 2, and the water flow through the hot water supply passage 5 can be changed by this operation.

The drain passage 6 is provided with the introduction water pipe 16.
And at a location near the connection location of the water flow detection mechanism 17, is drawn out of the hot water supply channel 5 through the drain cock 32, and further through the drain pipe 33 (shown in phantom lines in the figure).
It is derived from inside to outside.

Next, the heat-sensitive responsive valve 22 which is an important part of the present invention will be described.
Will be described in detail with reference to FIGS. 2 (a) and 2 (b).

The heat-sensitive responsive valve 22 has a substantially cylindrical valve body 35 concentrically inserted into a substantially cylindrical body 34 thereof.
And a spring 36 as urging means for urging the valve body 35 to the open position, and a spring 37 made of a shape memory alloy as a valve drive unit for driving the valve body 35 to open and close.

The main body 34 has a bottomed cylindrical valve case with its front end closed by a bottom wall 34a formed integrally with the outer peripheral side. ,
An inlet-side pipe connection 38 which is an end opening is formed. An outlet-side pipe connection portion 39 which is a side opening communicating with the inlet-side pipe connection portion 38 via the inside of the main body portion 34 is formed on the outer peripheral side portion of the main body portion 34.

In this case, the heating water pipe 21 and the outlet water pipe 23 of the hot water supply passage 5 are connected to the inlet-side pipe connection 38 and the outlet-side pipe connection 39 of the thermoresponsive valve 22, respectively (see FIG. 1).
Is connected.

The valve body 35 is inserted into the main body 34 so as to be movable in the axial direction, and the movement thereof causes the main body 3 to move.
4 is opened and closed between the two pipe connection portions 38 and 39.

That is, on the inner peripheral surface of the main body portion 34, a portion between the two pipe connection portions 38 and 39 (the outlet side pipe connection portion 39) is provided.
Of the body 34 closer to the inlet-side piping connection 38)
And a portion between the outlet side pipe connection portion 39 and the bottom wall portion 34a (the bottom wall portion 34 of the main body portion 34 more than the outlet side pipe connection portion 39).
a) and the bottom wall portion 34a of the main body portion 34
The inclined surfaces 40 and 41 (annular valve seats) whose diameter gradually decreases toward the side are formed.
The valve body 35 is attached to the outer peripheral portion of the distal end portion at the bottom wall portion 3.
As shown in FIG. 2 (b), O-rings 42, 43 which are in sliding contact with the inclined surfaces 40, 41 over the entire circumference are inserted into the inclined surfaces 40, 41 when moved toward the 4a side. And valve element 3
5 is, as shown in FIG.
And the O-rings 42 and 43 are respectively
In the state separated from 0, 41, gaps 44, 45 are formed between the rear end and the front end of the valve body 35 and the inner peripheral surface of the main body 34 at the inclined surfaces 40, 41, respectively. I have to. In addition, since the valve body 35 is substantially cylindrical as described above, its axial center portion is a through hole.

Accordingly, as shown in FIG. 2A, the valve body 35 is moved to the position on the inlet side pipe connection portion 38 side (hereinafter, referred to as "the valve body 35").
In the open position), the two pipe connections 38 and 39 are
4 or through the inside of the valve body 35 and the gap 45, and as shown in FIG.
At the position where the O-rings 42 and 43 are moved to the 4a side and slidably contact the inclined surfaces 40 and 41, respectively (hereinafter referred to as closed positions), the two pipe connection portions 38 and 39 are shut off via the O-rings 42 and 43.

An annular spring seat 46 is fixed to the inner peripheral surface of the main body 34 at a position between the rear end of the valve body 35 and the inlet-side pipe connection section 38. The movement to the side pipe connection portion 38 side is regulated by the stopper 47 fixed to the rear end of the valve body 35 abutting on the spring seat 46.

On the other hand, the spring 36 has an annular jaw 48 formed at an intermediate portion of the inner peripheral surface of the valve body 35 and a main body 34.
, And biases the valve body 35 toward the open position. A spring 37 made of a shape memory alloy is interposed between the annular jaw 48 of the valve body 35 and the spring seat 46 to urge the valve body 35 toward the closed position.

In this case, the spring 37 made of a shape memory alloy is made of a shape memory alloy in which a load generated in accordance with the temperature of water flowing from the inlet side pipe connection portion 38 in the main body portion 34 changes. When the temperature of flowing water is 80 ° C. or lower, the load becomes small, and when the temperature is 90 ° C. or higher, the load becomes large.

As shown in FIG. 2 (a), when the load of the spring 37 is small, the generated load is set to be sufficiently smaller than the generated load of the spring 36. The generated load of the spring 36 becomes larger than the generated load of the spring 37,
The valve body 35 is moved to the open position by the urging force of the spring 36.

On the contrary, as shown in FIG. 2 (b), when the load of the spring 37 is large, the generated load is set to be sufficiently larger than that of the spring 36. Then, the generated load of the spring 37 becomes larger than the generated load of the spring 36,
The valve body 35 is moved to the closed position by the urging force of the spring 37.

Therefore, the spring 37 made of a shape memory alloy opens and closes the valve body 35 by a change in shape according to the temperature of the water flow.

Since the valve body 35 of the thermoresponsive valve 22 penetrates through the inside thereof, it does not move from the open position to the closed position depending on the flow of water from the inlet-side piping connection portion 38. .

Next, the structure of the thermoresponsive valve 28 provided in the intermediate water pipe 19 will be described in detail with reference to FIGS. 3 (a) and 3 (b).

The thermoresponsive valve 28 includes a substantially cylindrical valve body 51 having one end closed in a substantially cylindrical main body 50.
A spring 52 for urging the valve element 51 to the open position and a spring 53 made of a shape memory alloy for driving the valve element 51 to open and close according to the water temperature are provided.

In this case, an inlet-side pipe connecting portion 54 and an outlet-side pipe connecting portion 55 are formed at both open end portions of the main body 50, respectively. The portion of the water pipe 19 on the water detection mechanism 17 side and the portion on the heat exchanger 4 side are connected (see FIG. 1). The inner peripheral surface of the main body 50 has a small-diameter inner peripheral portion 50a formed on the inlet-side piping connection portion 54 side and an outlet-side piping connection portion 55 from the small-diameter inner peripheral portion 50a via the inner peripheral step portion 50b. And a large-diameter inner peripheral portion 50c formed on the side.

The valve body 51 is provided with a large-diameter inner peripheral portion 50 of the main body 50.
The inside of the main body 50 is opened and closed by being moved inside the body 50c so as to be movable in the axial direction.

That is, the inlet side pipe connection portion 5 of the valve body 51
The end on the fourth side is closed by a bottom wall portion 56 formed integrally with the outer peripheral side portion of the valve body 51, and the bottom wall portion 56 has a larger diameter than the small diameter inner peripheral portion 50 a of the main body 50. Is formed. When the valve body 51 is moved to the small-diameter inner peripheral portion 50a side, the inner peripheral step portion 50b of the main body 50 is contacted with the peripheral edge of the end surface portion of the bottom wall portion 56 on the small-diameter internal peripheral portion 50a side. The contacting annular packing 57 is fixed. In addition, the valve element 5
The first open end 58 is slidably contacted with the large-diameter inner peripheral portion 50c of the main body 50 over the entire circumference, and a plurality of water holes 59 are formed in the outer peripheral side of the valve body 51.

Accordingly, as shown in FIG. 3 (a), the valve element 51 is moved to the outlet side pipe connection portion 55 side and the bottom wall portion 56 is moved.
At a position separated from the inner peripheral step 50b of the main body 50 (hereinafter referred to as an open position), the inlet side pipe connecting portion 54 is connected to the inside of the small-diameter inner peripheral portion 50a of the main body 50 and the water hole 5 of the valve body 51.
9 and the large-diameter inner peripheral portion 50c of the main body 50, and communicates with the outlet-side piping connection portion 55. As shown in FIG. In a position where the portion 56 is pressed against the inner peripheral step portion 50b via the annular packing 57 (hereinafter, referred to as a closed position), the two pipe connection portions 5
4 and 55 are shut off through the bottom wall 56 and the annular packing 57.

At a position between the open end 58 of the valve body 51 and the outlet-side pipe connection portion 55, a plurality of water holes 60 are formed in the large-diameter inner peripheral portion 50c of the main body 50. The annular spring seat 61 is fixed, and the movement of the valve body 51 toward the outlet-side pipe connection portion 55 is regulated by the opening end 58 of the valve body 51 abutting on the spring seat 61.

On the other hand, the spring 52 is interposed between the open end 58 of the valve body 51 and the inner peripheral step 50b of the main body 50, and biases the valve body 51 to the open position. Also,
A spring 53 made of a shape memory alloy is interposed between the bottom wall portion 56 of the valve body 51 and the spring seat 61 and urges the valve body 51 toward the closed position.

In this case, similarly to the thermoresponsive valve 22,
The spring 53 made of a shape memory alloy is made of a shape memory alloy in which a load generated according to the temperature of water flowing backward from the outlet side pipe connection portion 55 in the main body 50 varies as described later. When the temperature is below 80 ° C,
When the load is small, and when the temperature is 90 ° C. or more, the load is large.

As shown in FIG. 3 (a), when the load of the spring 53 is small, the generated load is set to be sufficiently smaller than the generated load of the spring 52. The generated load of the spring 52 becomes larger than the generated load of the spring 53,
The valve element 51 is moved to the open position by the urging force of the spring 52.

Conversely, as shown in FIG. 3B, when the load of the spring 53 is large, the generated load is set to be sufficiently larger than that of the spring 52. Then, the generated load of the spring 53 becomes larger than the generated load of the spring 52,
The valve element 51 is moved to the closed position by the urging force of the spring 53.

Accordingly, the spring 53 made of a shape memory alloy, like the spring 37 of the thermoresponsive valve 22, changes its shape in accordance with the temperature of the flowing water, so that the valve body 51 is formed.
To open and close.

Next, the operation of the water heater 1 will be described.

Referring to FIG. 1, in this water heater 1, when one of the hot water taps 26 and 27 is opened, the intermediate water pipe 19, the heating water pipe 21 and the outlet water pipe 23 of the hot water supply pipe 5 extend from the introduction water pipe 16 to the hot water pipe 5. Are sequentially passed to the faucet 24 or the shower head 25.

At this time, the water flow in the hot water supply path 5 is detected by the diaphragm 30 of the water flow detection mechanism 17 provided in the middle of the hot water supply path 1, and in response to this, the water governor 29 controls the gas valve 12 in the gas passage 7. Is opened. When the gas valve 12 is opened, the gas is supplied to the gas burner 3 of the combustor 4 through the gas passage 7 as described above, and the gas is burned. Is heated via the main body 15 of the heat exchanger 4 in the heating water passage 21. Then, hot water is supplied to the faucet 24 or the shower head 25 by this heating.

In this case, the hot water supply temperature is set to a normal temperature of, for example, 40 to 50 ° C. by a user or the like via an operating device (not shown). The operation is appropriately controlled by a controller (not shown) so as to reach the set temperature.

At such a normal hot water supply temperature, as shown in FIGS. 2 (a) and 3 (a), the springs 37, 53 made of a shape memory alloy of the heat-sensitive responsive valves 22, 28 are provided. The generated load is in a small state, and accordingly, the valve bodies 35 and 51 of the thermosensitive valves 22 and 28 have been moved to the open positions.

On the other hand, in the water heater 1, for example, when the water governor 29 or the diaphragm 30 of the water flow detecting mechanism 17 malfunctions, the gas valve 12 does not flow even though the hot water path 5 has no water flow. May open, so-called residual fire may occur in the heat exchanger 4. In this case, the operation of the heat exchanger 4 is stopped by an overheating prevention device (not shown), The water in 21 may be heated to a high temperature by the afterglow and its pressure may be high. In this case, the pressure of the heating water pipe 21 is set by the overpressure relief valve 20 so as not to exceed 17.5 kgf / cm ^2, for example. The water in the heating water pipe 21 may be heated to, for example, 150 to 180 ° C.

When the hot water taps 26 and 27 are opened in a state where the water in the heating water pipe 21 is heated to a high temperature, the hot water in the heating water pipe 21 is led out through the thermosensitive valve 22. An attempt is made to flow into the water pipe 23.

However, as shown in FIG. 2 (a), at this time, when high-temperature hot water flows from the heating water pipe 21 into the main body 34 through the inlet side pipe connection portion 38 of the thermosensitive valve 22, Since the hot water directly touches the spring 37 made of the shape memory alloy of the thermoresponsive valve 22, it immediately
As shown in (b), the spring 36 is in a state where the generated load is large, and the valve body 35 is moved to the closed position, whereby the outlet side of the thermoresponsive valve 22 connected to the outlet water pipe 23 is connected. The pipe connection portion 39 is connected to the O-ring 4 of the valve body 35.
It is shut off from the inlet-side piping connection part 38 via 2 and 43. Therefore, the hot water flowing into the main body 34 from the heating water pipe 21 does not flow out to the outlet water pipe 23, so that the hot water flows into the faucet 24 or the shower head 2.
5 is blocked.

In this case, since the spring 37 made of a shape memory alloy is always provided at a place communicating with the heating water pipe 21 via the inlet side pipe connection part 38, the load of the spring 37 is large. The state is maintained until the temperature of the hot water in the heating water pipe 21 decreases, so that the valve body 3
5 is maintained in the closed position.

In FIG. 1 and FIG. 3, when an after-fire occurs as described above, the water in the heating water pipe 21 is heated to a high temperature and its pressure rises. When the hot water tries to flow backward from the heating water pipe 21 side to the resin pipe 16a through the heat-sensitive responsive valve 28, the intermediate water pipe 19 and the introduction water pipe 16, and such a back flow occurs,
There is a possibility that the resin piping 16a may be damaged by the hot water.

However, in this case as well, FIG.
As shown in (b), the spring 53 made of the shape memory alloy of the thermally responsive valve 28 immediately generates a large load due to contact with high-temperature hot water that tends to flow backward from the outlet side pipe connection portion 55 into the main body 50. In this state, the valve body 51 is moved to the closed position, whereby the hot water is prevented from flowing back from the heated water pipe 21 to the intermediate water pipe 19. In this case, the main body 5
Since the high-temperature hot water that is going to flow back into the chamber 0 has a high pressure, the pressure acts on the bottom wall 56 of the valve
1 is moved to the closed position.

Therefore, the hot water does not flow backward from the heating water pipe 21 to the introduction water pipe 16 and the pipe 16a, and the resin pipe 16a is not damaged by the hot water.

In this case, since the spring 53 made of a shape memory alloy is always provided at a location which is always in communication with the heating water pipe 21 via the outlet side pipe connecting portion 55, the load of the spring 53 is reduced. The large state is maintained until the temperature of the hot water on the side of the heating water pipe 21 decreases, so that the valve body 5
1 is maintained in the closed position.

Thus, in such a water heater 1,
The hot water is supplied to the faucet 2 when, for example, a residual heat of the heat exchanger 4 occurs.
4 and the shower head 25 are supplied with the thermoresponsive valve 2
2 prevents the hot water from flowing back into the inlet water pipe 16 and the pipe 16a.

[0059]

As is apparent from the above description, according to the water heater of the present invention, the valve provided in the bottomed cylindrical valve case provided in the middle of the hot water supply path at the downstream side of the heat exchanger. In the open position, the body communicates between the end opening and the side opening through a first gap closer to the end opening than the side opening of the valve case, and the side opening of the valve case. The end opening and the side opening communicate with each other through the second gap closer to the bottom and the through hole of the valve body, and when the valve body is in the closed position, the valve body is connected to the first gap and the second gap. The valve body is configured to abut on the inner peripheral portion of the valve case at the gap 2 to block the gap between the end opening and the side opening. When the heat exchanger is driven from the open position to the closed position, When the water in the hot water supply path on the side is heated to a high temperature, the hot water can be reliably and promptly prevented from being supplied, and when the temperature of the water drops, the valve body is returned to the open position smoothly. Hot water can be supplied without any trouble.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a water heater according to the present invention;

2A is a longitudinal sectional view of an example of a thermal responsive valve as an essential part of the present invention in an open state, FIG. 2B is a longitudinal sectional view of the thermal responsive valve in a closed state,

FIG. 3A is a vertical cross-sectional view of a thermoresponsive valve having a shape memory alloy provided in the water heater in an open state, and FIG. 3B is a vertical cross-sectional view of the thermosensitive valve in a closed state.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hot water heater, 4 ... Heat exchanger, 5 ... Hot water supply path, 22 ... Heat sensitive valve, 35 ... Valve, 37 ... Spring (valve drive part) made of shape memory alloy.

Claims (1)

(57) [Claims] 1. A water heater for supplying hot water via a hot water supply passage passing through a heat exchanger, wherein the hot water supply is provided at an intermediate portion of the hot water supply passage at a downstream side of the heat exchanger, and the inside thereof is provided at one end and a side surface. A bottomed cylindrical valve case which is communicated upstream and downstream of a middle part of the hot water supply path via an end opening and a side opening formed respectively, and from the end opening side in the valve case. Between the open position communicating between the end opening and the side opening and the closed position blocking the space between the end opening and the side opening. A valve body provided movably in the axial direction of the valve case, and engaging with the valve body in the valve case to open and close the valve body by thermal deformation according to the temperature of hot water in the valve case. A valve drive unit made of a shape memory alloy, wherein the valve body is in its open position. First and second gaps are respectively formed between an inner peripheral portion of the valve case closer to the end opening than the side opening and an inner peripheral portion of the valve case closer to the bottom than the side opening. The end opening and the side opening are communicated with each other through the first gap, and the end opening and the side opening are connected to the second gap and the valve body in the axial direction of the valve case. And through the through hole formed through the valve body, and at the closed position of the valve body, abuts against the inner peripheral portion of the valve case at the first and second gaps and The valve drive unit is configured to shut off the end opening and the side opening by closing a gap, and when the hot water temperature in the valve case becomes equal to or higher than a predetermined temperature, the valve body When thermal deformation occurs to drive from the open position to the closed position, and when the temperature of the hot water falls below a predetermined temperature, the valve body is A water heater configured to cause a shape return to an open position.