JPH05126410A - Cooling device for controlling circuit board for hot water feeder - Google Patents

Abstract

PURPOSE:To protect electronic parts mounted on a controlling circuit board from heat generated from a heat exchanging part by cooling effectively the controlling circuit board in a hot water feeder. CONSTITUTION:In a hot water feeder 10 having therein a heat exchanging part 34 and a controlling circuit board 42, thermoelements 48 for power generation are disposed in relation to thermoelectric power generation with respect to the heat exchanging part 34, and thermoelements 50 for cooling are disposed in relation to thermoelectric cooling with respect to the controlling circuit board 42. In order to actuate the thermoelements 50 for cooling with a current generated by the thermoelements 48 for power generation, the thermoelements 48 for power generation are electrically connected to the thermoelements 50 for cooling. The cooling of the controlling circuit board 42 are automatically started in accordance with operation of the hot water feeder 10, and the cooling capability of the thermoelements 50 for cooling is increased in response to the rise of a temperature at the heat exchanging part 3.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a control circuit board of a water heater.

[0002]

2. Description of the Related Art As is well known, a water heater supplies hot water by heating the water by exchanging a relatively high temperature combustion gas generated by a burner with water in a heat exchange section. .. In order to be able to supply hot water of a desired temperature even when the required hot water supply amount has increased or decreased, or to adjust the temperature of the hot water to a desired arbitrary value, the burner thermal power generally becomes controllable. There is. Therefore, the amount of water and the actual hot water temperature are detected by various sensors, and the fuel supply amount to the burner is controlled so that the hot water temperature reaches the required temperature. The fuel supply amount is electronically controlled by an electronic control circuit, and such control circuit is composed of electronic parts and is usually incorporated in a control circuit board. The control circuit is also adapted to control the burner ignition device, the fuel tap, and the like.

The above-mentioned control circuit board is installed inside the water heater, but since the water heater is designed to be quite compact, it is necessary to provide a sufficient distance between the heat exchange section and the control circuit board. Have difficulty.

Therefore, during operation of the water heater, the heat radiated from the heat exchanging portion is transferred to the control circuit board and heats the control circuit board, so that it is necessary to cool the control circuit board.
In the conventional water heater, a part of the air from the fan for forcibly supplying and discharging the combustion air is sent to the control circuit board to air-cool the control circuit board.
However, such a conventional cooling method cannot be said to be sufficient, and when the temperature of the control circuit board rises, it may adversely affect the life and operation of the electronic component.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to effectively cool a control circuit board of a water heater to protect electronic components mounted on the control circuit board from heat of a heat exchange section. is there.

In another aspect of the present invention, it is an object of the present invention to provide a control circuit board cooling device which is capable of automatically cooling the control circuit board upon ignition of the burner and which does not require a switching element. Is to provide.

In still another aspect of the present invention, it is an object of the present invention to provide a control circuit board cooling device capable of cooling the control circuit board more strongly as the heat radiation amount of the heat exchange section increases. It is to be.

[0008]

[Constitution of the invention]

SUMMARY OF THE INVENTION The present invention intends to cool a control circuit board by utilizing the thermoelectric power generation effect (Seebeck effect) and thermoelectric cooling effect (Peltier effect) of a thermoelectric element.

Therefore, according to the present invention, the thermoelectric element for power generation is arranged in the heat exchange section of the water heater in the thermoelectric generation relation, and the cooling thermoelectric element is arranged in the thermoelectric cooling relation for the control circuit board. The thermoelectric element for power generation and the thermoelectric element for cooling are electrically connected in order to operate the thermoelectric element for cooling by the current generated by the thermoelectric element for power generation.

[0010]

[Function] When the burner is ignited to supply hot water and the temperature of the heat exchange section rises, the thermoelectric element for power generation generates electric power by the Seebeck effect according to the temperature of the heat exchange section, and supplies current to the thermoelectric element for cooling. To do. The cooling thermoelectric element cools the control circuit board by the Peltier effect according to the supplied current.

As described above, the cooling of the control circuit board is automatically started in response to the operation of the water heater, and the cooling capacity of the cooling thermoelectric element is increased in accordance with the rise in the temperature of the heat exchange section. Effective cooling is provided.

The above features and advantages of the present invention, as well as other features and advantages, will be more apparent as described in the following examples.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail with reference to the accompanying drawings showing the embodiments of the present invention.

FIG. 1 is a perspective view showing a conventional water heater equipped with a control circuit board cooling device of the present invention, as viewed from the front cover of the water heater, and FIG. 2 is a cooling device of the present invention. 2 is a schematic view of the water heater of FIG.

First, referring to these drawings, first, a brief description will be given of the general structure of the water heater. The water heater 10 itself is of a conventional type and includes a housing 12, a gas supply pipe 14, and
It has a water supply pipe 16 and a hot water supply pipe 18.

As can be seen from the schematic diagram of FIG. 2, the gas supply pipe 14 has a main solenoid valve 20 as a gas main plug.
And an electromagnetic proportional valve 22 with a governor for controlling the gas flow rate
Is installed. In the illustrated embodiment, the water heater 10 has two gas burners, a first gas burner 24 and a second gas burner 26, and is connected to each gas burner via a first solenoid valve 28 and a second solenoid valve 30. Gas is supplied.

As is known, gas burners 24 and 2
6 is arranged in the combustion cylinder 32 (FIG. 1),
A heat exchange section 34 is disposed above the. Combustion air is forcibly supplied into the combustion cylinder 32 by a fan 36, and after the combustion gas exchanges heat with water in the heat exchange section 34, it is forcibly discharged from the exhaust port 38 to the outside air by the action of the fan 36. To be done. Hot water obtained by heat exchange is the hot water supply pipe 18
It is supplied to the consumption place according to a well-known manner via a pipe (not shown) connected to.

A control box 40 (FIG. 1) is also provided in the housing 12, and a control board 42 is arranged in the control box as schematically shown in FIG. Electronic components (not shown) forming a control circuit of the water heater are mounted on the control board 42 in a known manner. This control circuit is of a conventional type, and controls the solenoid valves 20, 22, 28, 30 and the fan 36 on the basis of signals from the water amount sensor 44 and the water temperature sensor 46, for example, so that the heating power of the gas burner, and eventually the gas burner. It is configured to adjust the hot water supply temperature.

In accordance with the invention, the heat exchanging portion 34 is provided along its periphery with, for example, eight modules 4 of thermoelectric elements for power generation.
8 are attached (four of these power generation modules 48 are visible in FIG. 1, only three are shown in FIG. 2). Further, as shown in FIG. 2, for example, two cooling thermoelectric element modules 50 are joined to the control board 42. These modules 48 and 50 can be electrically connected, for example, in series by wires 52 and 54.

FIG. 3 is an enlarged view of a part of the cooling thermoelectric element module 50. A pair of thermoelectric elements are formed by joining a p-type semiconductor 56 and an n-type semiconductor 58 with a metal plate 60 in the form of a thermocouple. The element 62 is configured, and adjacent thermoelectric elements 62 in the same row are electrically connected to each other in series by metal terminals 64. In addition, the thermoelectric elements 62 in the front and rear rows
Are also electrically connected in series with each other. In this way
One module 50 can be constituted by 100 or more pairs of thermoelectric elements 62 connected in series with each other.
In that case, it is only necessary to connect one plus lead wire and one minus lead wire to each module. Each thermoelectric element module 50 has a ceramic substrate 6
6 and 68. Cooling thermoelectric element module 50
Is a Bi-T having good thermoelectric conversion ability at relatively low temperature.
It is preferably formed of an e-based semiconductor material. As shown in FIG. 2, a heat radiation fin 70 is provided on the heat generation side (heat radiation side) of the cooling thermoelectric element module 50.

FIG. 4 shows a thermoelectric element module 48 for power generation.
As an example, a large number of thermoelectric elements including a p-type semiconductor 72 and an n-type semiconductor 74 are arranged in the longitudinal direction of the ceramic substrate 76. The p-type semiconductor 72 and the n-type semiconductor 74 of each thermoelectric element are directly joined by the hot pressing method at their upper ends to form a thermocouple. Front and back p
The type semiconductor 72 and the n-type semiconductor 74 are electrically connected to each other in series by a metal terminal 78. In this way, the thermoelectric element module 48 for power generation can be configured by connecting several tens to 100 or more pairs of thermoelectric elements in series. Positive and negative terminals are connected to the metal terminals at both ends in the module (only one of them 80 is shown in FIG. 4). Ceramic substrate 76
A heat radiation fin can be provided on the back surface of the. Considering that the heat exchanging unit 34 of the water heater is exposed to a relatively high temperature, the thermoelectric element module 48 for power generation installed in the heat exchanging unit 34 is a Fe-S that exhibits good thermoelectromotive force characteristics at a high temperature.
It is preferably formed of an i-based semiconductor material. However, when the water heater is designed so that the heat exchange section 34 is in contact with an atmosphere of a relatively low temperature, the structure shown in FIG. 3 may be formed using a Bi—Te based semiconductor material.

FIG. 5 schematically shows a cooling device 90 of the present invention for cooling the control board 42. In order to simplify the drawing, the thermoelectric element module 48 for power generation and the thermoelectric element module 50 for cooling are respectively arranged. Each is shown as consisting of only one pair of thermoelectric elements. To explain the operation of the cooling device 90 mainly with reference to FIG. 5, the gas burner 24
When 26 and 26 are ignited and the temperature of the heat exchange part 34 rises, the pn junction part of the thermoelectric element module 48 for power generation is heated to a high temperature, but the ceramic substrate 76 radiates heat because it is in contact with a lower temperature atmosphere. .. As a result, a temperature gradient is generated between the pn junction of each thermoelectric element 62 of the power-generating thermoelectric element module 48 and the heat radiation side terminal 78, so that the Seebeck effect causes the thermoelectric element module 48 to generate a thermoelectromotive force and the plus terminal 80. A voltage is generated between the negative terminal and the negative terminal.

Thus, the thermoelectric element module 48 for power generation
The electric current generated by is supplied to the cooling thermoelectric element module 50 via the wirings 52 and 54. When the thermoelectric element module 50 for cooling is energized, the heat absorption side ceramic substrate 66 absorbs heat due to the Peltier effect, and the control substrate 4
Cool 2. The heat of the ceramic substrate 68 on the opposite side is radiated to the atmosphere.

As the gas burner is extinguished and the heat exchange section 34 cools down by radiating heat, the thermoelectromotive force of the thermoelectric element module 48 for power generation is reduced and the cooling action of the thermoelectric element module 50 for cooling ends.

[0025]

As described above, according to the cooling apparatus of the present invention, the cooling of the control circuit board 42 is automatically started with the ignition of the burner, so that the electronic parts mounted on the control circuit board 42 are heated. The heat of the exchange part 34 can be effectively protected. As a result, it is possible to extend the life of electronic components mounted on the control circuit board and ensure proper operation of the control circuit.

From another point of view, the electromotive force of the thermoelectric element 48 for power generation increases as the temperature of the heat exchanging section 34 rises, and the cooling capacity of the thermoelectric element 50 for cooling increases accordingly. It is possible to ideally cool the control circuit board 42 without separately providing the control circuit.

In yet another aspect, the thermoelectric element 48 for power generation generates power only when the burner is ignited, and therefore also functions as a switching element for the thermoelectric element 50 for cooling. Therefore, it is not necessary to separately provide a switching element, and it is possible to realize a simple and compact water heater.

In another aspect, the cooling device of the present invention has the advantage of not requiring a power source such as a battery.

[Brief description of drawings]

FIG. 1 is a perspective view showing a water heater equipped with a control circuit board cooling device according to an embodiment of the present invention, as seen from a front cover of the water heater removed.

FIG. 2 is a schematic diagram of the water heater of FIG.

FIG. 3 is an enlarged view of a part of the cooling thermoelectric element module.

FIG. 4 is an enlarged view of a part of the thermoelectric element module for power generation.

FIG. 5 is a schematic view of a cooling device of the present invention using a thermoelectric element.

[Explanation of symbols]

 10: Water heater 34: Heat exchange part 42: Control circuit board 48: Thermoelectric element module for power generation 50: Thermoelectric element module for cooling 62: Thermoelectric element 90: Cooling device

Claims (1)

[Claims] 1. A water heater including a heat exchange section and a control circuit board, wherein a thermoelectric element for power generation is arranged in the heat exchange section in a thermoelectric power generation relationship, and cooling is performed in the control circuit board in a thermoelectric cooling relationship. A thermoelectric element for power generation, and the thermoelectric element for cooling and the thermoelectric element for cooling are electrically connected so that the thermoelectric element for cooling is operated by the current generated by the thermoelectric element for power generation. Plate cooling system.