JPH0223965Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an open type combustion device such as an open type instantaneous water heater. A rod-shaped heat conductive member is provided in the secondary air ascending path, and when the temperature of the member that stores the conductive heat from the heat conductive member exceeds the set value,
The present invention relates to an open-type combustion device that is provided with a long-time combustion prevention mechanism that automatically stops fuel supply to the burner to ensure safety against an increase in indoor CO concentration due to long-term combustion.

[Prior art]

Application for an open type combustion device as mentioned above was made in 1986-152345.
In this method, as shown in FIG. 8, the rod-shaped heat conductive member 17 is simply disposed in the combustion secondary air ascending path A between the flame openings 3A of the burner 3. The technology remained unchanged.

[Problem that the invention attempts to solve]

However, in the case of the above-mentioned prior art, although it has the advantage that the operating performance of the long-term combustion prevention mechanism can be more stabilized compared to arranging the rod-shaped heat conductive member in the combustion chamber above the burner, the amount of fuel supplied is When the heating capacity of the burner is changed to a small value through control, it takes a long time for the long-term combustion prevention mechanism to activate, resulting in a delay in the activation of the long-term combustion prevention mechanism, so there is room for improvement in terms of safety. Ta.

In other words, when the heating capacity is changed to a small value, the amount of heat applied to the rod-shaped heat conductive member decreases. Furthermore, due to the cooling effect of the combustion secondary air on the rod-shaped heat conduction member, which has a lower rate of decrease than the heating capacity decrease, the degree of rise in temperature T of the heat storage member as time t elapses, as shown by the broken line in Fig. 6. is much lower when the heating capacity is small than when the heating capacity is large. This results in a wide activation delay (△t′a).

The purpose of the present invention is to eliminate the large dispersion in the time it takes for the long-term combustion prevention mechanism to operate between high heating capacity and low heating capacity, or, in other words, to reduce the large activation delay when the heating capacity is small. There are areas for improvement.

[Means to solve the problem]

A characteristic configuration of the open type combustion apparatus according to the present invention is that a shielding member for preventing combustion secondary air from being blown against the rod-shaped heat conductive member disposed in the combustion secondary air ascending passage between the burner flame ports is provided in the secondary air ascending passage. The functions and effects are as follows.

[Effect]

In other words, by blocking the flow of combustion secondary air in the combustion secondary air ascending path, the combustion state at the burner mouth above the shielding member is changed, and the combustion secondary air is blown against the rod-shaped heat conduction member. By suppressing the cooling effect, it is possible to reduce the difference in the degree of rise in temperature T of the heat storage member over time t between when the heating capacity is large and when the heating capacity is small, as shown by the solid line in Fig. 6. In other words, with respect to the setting of the long-term combustion prevention device and the operating temperature Ta, the difference (△ta) between the time t when the long-term combustion prevention device is activated is large heating capacity and small heating capacity. For example, it is possible to effectively prevent the time t ₂ required for the mechanism to operate when the heating capacity is small from becoming longer than the time t ₁ required for the mechanism to operate when the heating capacity is large.

[Effect of idea]

As a result of the above, although it is possible to suppress the increase in production costs associated with improvements with an extremely simple improvement that involves just adding a shielding member, it is possible to suppress the increase in production costs due to improvements, while also preventing automatic combustion shutdown to prevent long-term combustion due to changes in heating capacity. We were able to perform this stably with little disturbance, further improving safety.

Furthermore, considering that CO is generated due to incomplete combustion due to a decrease in indoor O ₂ concentration due to combustion exhaust gas, and incomplete combustion due to heat exchanger clogging, etc., the amount of CO generated is lower when the heating capacity is low. Slightly,
It is permissible for the long-term combustion prevention mechanism to operate for a long time when the heating capacity is low, but the long-term combustion prevention mechanism is not based on changes in heating capacity, but is originally related to heating capacity. Even though it is a safety device that uses combustion time as an activation factor, which automatically stops combustion after a predetermined period of time, the long-term combustion prevention mechanism is activated at high heating capacity and low heating capacity. The small variation allows the user to recognize that the long-term combustion prevention mechanism is operating properly as a safety device, and does not give the user unnecessary anxiety regarding safety.

〔Example〕

Fig. 5 shows an instantaneous water heater which is an example of an open type combustion device, in which a main burner 3 with rows of flame ports 3A arranged side by side is housed in a casing 2 with an exhaust port 1 formed on the top surface. A Finch-Hube type water heating heat exchanger 5 is installed in the combustion chamber 4 of the main burner 3.

In the figure, 6 is a pilot burner, 7 is a side pilot burner for igniting the pilot burner 6, and 8 is a spark plug.

In the fuel gas supply path 9 to the main burner 3,
A main gas valve 10 that is manually opened and closed, a water volume responsive valve 11 that is opened only when the amount of water supplied to the heat exchanger 5 is equal to or higher than a set water amount based on the detection of the amount of water supplied to the heat exchanger 5, a gas governor 12, and a main gas valve that is manually operated to open and close. A heating capacity switching valve 13 that switches the amount of fuel supplied to the burner 3 in two stages, large and small, is installed, and a heating capacity switching valve 13 is installed in the supply path 9 upstream of these valves in conjunction with the opening operation of the main gas valve 10 by manual operation. opened and operated,
In addition, an electromagnetic safety valve 15 is installed which is opened and held by an electromotive force greater than the set value of the thermocouple 14 heated by the pilot burner 6, so that when the pilot burner 6 is extinguished, the burners 3, 6, A combustion safety mechanism is configured to automatically cut off fuel supply to 7.

As shown in FIG. 1 to FIG.
The combustion chamber 4 is arranged in the combustion secondary air ascending path A between the burner ports 3A in a posture along the longitudinal direction of the combustion chamber 4 so that it rushes into the inside from the outside, and conduction from the heat conduction member 17 as the main burner 3 burns. A heat storage member 18 that stores heat and radiates heat naturally when the main burner 3 is extinguished.
is attached to the outer end of the combustion chamber of the rod-shaped heat conducting member 17, and further, when the detected temperature T becomes equal to or higher than the set Ta based on the temperature detection of the heat storage member 18,
The temperature switch 20 that opens the thermoelectromotive force circuit 19 connecting the thermocouple 14 and the electromagnetic safety valve 15 is connected to the heat storage member 1.
8, and detects the temperature rise of the heat storage member 18 due to the heating operation of the water heater. The electromagnetic safety valve 15 is then closed to stop the heating operation, thereby forming a long-term combustion prevention mechanism that limits the increase in indoor CO concentration due to continuous heating operation.

In the combustion secondary air ascending passage A in which the rod-shaped heat conduction member 17 is disposed, below the heat conduction member 17,
In contrast, a plate-shaped shielding member 21 that prevents rising secondary air from being directly blown is installed at the flame opening forming part of the main burner 3 so that the secondary air supply to the combustion flame of the main burner 3 is not impaired. The cooling effect of the combustion secondary air on the rod-shaped heat-conducting member 17 becomes a disturbance and the long-term combustion prevention mechanism is activated. It is configured to prevent large fluctuations.

In other words, in the absence of the shielding member 21, due to the cooling effect of the rising secondary air on the rod-shaped heat conducting member 17, the temperature T of the heat storage member 18 increases over time, as shown by the broken line in FIG. There is a large difference between large heating capacity and small heating capacity, and as a result, the time t′ required for the long-term combustion prevention mechanism to operate at high heating capacity, relative to the set operating temperature Tb of the long-term combustion prevention mechanism. There is a large difference (△t′a) between ₁ and the time _t′2 required for the long-term combustion prevention mechanism to operate when the heating capacity is small.
However, by providing the shielding member 21 to suppress the cooling effect of the secondary air on the rod-shaped heat conducting member 17 and reducing the disturbance influence of the cooling effect, the solid line shown in FIG. As shown in , the difference in the degree of temperature T rise of the heat storage member 18 over time between the large heating capacity and the small heating capacity is made small, and thereby, for the set operating temperature Ta,
The structure is configured to reduce the gap (△ta) between the time t ₁ until the long-term combustion prevention device operates when the heating capacity is large and the time t ₂ when the long-term combustion prevention device activates when the heating capacity is small. It has been done.

On the other hand, the stay 22 for supporting the rod-shaped heat conduction member 17 and the heat storage member 18 is formed of a bent plate-like body having a shape that partitions the heat storage member 18 and the inside of the combustion chamber 4. By blocking radiant heat from the flame from directly reaching the heat storage member 18 with the plate-shaped stay 22, the direct heat radiation is prevented from becoming a disturbance and causing the operation of the long-term combustion prevention mechanism to become unstable. At the same time, in order to attach the heat storage member 18 to the stay 22, a heat insulating member 2 made of ceramic or the like is formed with a hole through which the rod-shaped heat conductive member 17 passes.
3 is interposed between the heat storage member 18 and the stay 22,
In addition to taking into consideration direct heat radiation, it is also designed to prevent the heat transmitted from the stay 22 to the heat storage member 18, which is heated to a high temperature by heat radiation from the combustion flame of the main burner 3, from becoming a disturbance. .

In other words, when the heat insulating member 23 is not installed, the combustion secondary air is cooled as shown by the broken line in FIG. 7 due to the influence of heat transmitted from the stay 22 heated by radiant heat to the heat storage member 18 Similar to the effect of the action, the rise in temperature T of the heat storage member 18 over time differs greatly between when the heating capacity is large and when the heating capacity is small, and this causes the set operating temperature Tc of the long-term combustion prevention mechanism to On the other hand _, there is _a large difference (△t′ b) occurs, but the main burner 3 is
As shown by the solid line in FIG. 7, by minimizing the disturbance influence caused by heat radiation from the combustion flame of By minimizing the difference between the operating temperature when the heating capacity is small and the time t ₃ required for the long-term combustion prevention mechanism to operate when the heating capacity is large, and the long-term combustion prevention mechanism when the heating capacity is Distance from time t ₄ until activation occurs (△tb)
It is configured to make it small.

In summary, the activation timing of the long-term combustion prevention mechanism can be improved by suppressing disturbances caused by the cooling effect of the combustion secondary air and by suppressing disturbances caused by heat radiation from the combustion flame of the main burner 3. It is designed to be more stable.

[Another example]

The materials of the rod-shaped heat conductive member 17, the heat storage member 18, and the heat insulating member 23 can be changed as appropriate.

Based on the temperature detection of the heat storage member 18, when the detected temperature T exceeds the set value, the burners 3, 6, 7 are activated.
Various improvements can be made to the temperature detection structure, circuit structure, or valve structure for automatically cutting off the fuel supply to the engine.

The present invention can be applied to various open type combustion devices such as open type instantaneous water heaters and space heaters.

[Brief explanation of the drawing]

1 to 7 show embodiments of the present invention,
FIG. 1 is an enlarged view showing the mounting structure of the rod-shaped heat conductive member, FIG. 2 is a plan view of the same, FIG. 3 is a rear view of FIG. 1, and FIG. 4 is a sectional view taken along the line - in FIG. 5 is an overall schematic diagram of the water heater, and FIGS. 6 and 7 are graphs showing experimental results, respectively. FIG. 8 is a diagram showing a conventional mounting structure for a rod-shaped heat conductive member. DESCRIPTION OF SYMBOLS 1...Burner, 3A... Flame port, 17... Rod-shaped heat conduction member, 18... Heat storage member, 21... Shielding member, A... Combustion secondary air ascending path.

Claims (1)

[Scope of utility model registration request] A rod-shaped heat conduction member 17 is provided in the combustion secondary air ascending path A formed between the burner ports 3A of the burner 3 whose fuel supply amount can be adjusted, and the temperature of the member 18 that stores the conductive heat from the heat conduction member 17 is The open type combustion device is equipped with a long-term combustion prevention mechanism that automatically stops the fuel supply to the burner 3 when the temperature exceeds a set value, and the combustion secondary air is not blown onto the heat conductive member 17. An open type combustion apparatus in which a shielding member 21 for blocking the combustion secondary air is provided in the combustion secondary air ascending path A.