JPS6143620B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heat exchanger for a bathtub equipped with a heat-sensitive element for preventing dry heating, and an object of the present invention is to ensure reliable operation without impairing combustion performance. do.

As shown in FIG. 1, one embodiment of a conventional heat exchanger of this type is such that the wall surface of a connecting chamber 2 to which each heat exchange element 1 is connected, which does not come into contact with the combustion gas, is recessed toward the indoor side to form a bottomless recess 3. The edge of the recess 3 is welded to the opposite wall to make a single-walled bottom 4, and a heat-sensitive element 5 for preventing dry heating is installed in the recess 3. Therefore, in order to speed up heat sensitivity, the bottom of the recess 3 was removed and then welded to the opposing wall to form a single wall, which was complicated in terms of structure and work.

Further, in FIG. 2 of the second embodiment, the entrance/exit holes 6, 7
A recess 9 was provided in a part of the heat exchange element 8 through which hot water flows, and a heat sensitive element 5 for preventing dry heating was provided adjacent to the recess 9. Therefore, the heat sensing element 5 senses heat through the double wall, and when there is no hot water in the heat exchange element 8, there is a large air space between them, so there is a long delay in detecting dry heating.

Further, in FIG. 3 of the third embodiment, one heat exchange element 11 is arranged at a higher position than the other heat exchange elements 10, and a heat sensitive element 5 for preventing dry heating is attached to this. Therefore, only the heat exchange element 11 is located at a different position than the other elements, making it difficult to manufacture the heat exchanger, and the flow of combustion gas in the burner located below the heat exchanger lacks uniformity (heat exchanger Replacement element 1
1 has low resistance and high excess air ratio), so the heating load becomes inconsistent.

The present invention improves the drawbacks of the various conventional examples described above, and one embodiment will be described below with reference to the drawings.
12 is a heat exchanger, and a heat exchange element 13 is made of a hollow plate made by press-molding two metal plates and then welding them together.
It is configured by arranging multiple sheets in parallel. Each heat exchange element 13
The upper and lower ends of one end are connected to each other via a connecting pipe 14 to be integrated, and a gap 15 is formed therebetween for passage of combustion gas. Further, each heat exchange element 13 has a curved portion 16 on its lower surface extending from one end in the heating width L direction toward the connecting pipe 14 to reduce fluid resistance. In addition, the upper surface of each heat exchange element 13 is gradually inclined 17 upward in the range of the diameter of the outlet pipe, which will be described later, as it goes toward the connecting pipe 14 side, thereby smoothing the flow of the hot metal. 18 and 19 are heat exchange elements 1 located at the ends facing the upper and lower connecting pipes 14;
31, an outlet pipe and an inlet pipe connected to a wall 131a that does not come into contact with combustion gas; 20, a heat-sensitive element such as a thermal switch that detects the temperature of the heat exchange element 13 and stops fuel supply to the burner during dry firing; Inlet/outlet pipe 1 in heating width L direction of heat exchange element 131
It is provided at the end of the wall 131a opposite to the 8 and 19 sides and at the top of the heating length direction H where the hot water temperature is highest. The structure of the heat exchange element 131 to which the heat sensitive element 20 is attached will be described in detail.
Reference numeral 21 denotes a recess for mounting a heat-sensitive element formed by bulging inward a wall 131a that does not come into contact with the combustion gas, and is set to a height that bulges out from the outer surface of the wall 131b of the heat exchange element 131 that comes into contact with the combustion gas. 22 is wall 13
1b is a convex portion facing the recess 21 and protruding toward the interval 13 side with a gap 24 left in between;
This is because the temperature rises due to active contact with combustion gas. 23 is a concave portion 21 that protrudes from the center of the convex portion 22;
This is to conduct heat to the concave portion 21 with the small convex portion brought into contact with the concave portion 21 .

In the above embodiment, the low-temperature hot water flowing from the inlet pipe 19 flows into the curved portion 1 as shown by the arrow in FIG.
6 into the lower part of the heat exchange elements 13, 131, and combustion gas from a burner (not shown) located at the lower part of the heat exchanger 12 ascends the interval 15 to heat and exchange heat. The hot water whose temperature has increased through this heat exchange rises as shown by the arrow in FIG.
This results in smooth natural convection.

Heat exchanger 12 that heats low-temperature hot water in this way
, when the hot water decreases due to a sudden accident and the hot water becomes dry, the concave portion 21 protrudes outward from the wall 131b, and the convex portion 22 protrudes from the wall 131b and faces into the interval 15, so that the combustion gas is not exposed to the hot water. The directly heated convex portion 22 rapidly rises in temperature, and this heat is efficiently transmitted to the concave portion 21 via the small convex portion 23, and as a result, the heat-sensitive element 20 operates quickly. In other words, during normal heating (when water is present),
Although the bottom surface of the recess 21 in which the heat-sensitive element 20 is provided is in contact with the small protrusion 23, the area in contact with the water present in the gap 24 is large, so the temperature does not rise rapidly.

Next, in case of abnormal heating (dry heating without water),
The temperature of the wall surface 131b on the side that comes into direct contact with the combustion gas rises rapidly, but the recess 21 in which the heat-sensitive element is provided
The temperature will gradually rise due to heat conduction. In this case, the operation of the heat-sensitive element 20 cannot be made faster, so the operation of the heat-sensitive element 20 can be made faster by bringing the small convex portion 23 and the bottom of the recess 21 into contact with each other at a portion to improve heat conduction. Ta.

In other words, the area in contact with water and the area in contact are related. Moreover, the uneven portion 21,
Since the gap 24 between the heat exchange elements 131 and 22 is incomparably narrower than the original space of the heat exchange element 131 to reduce the air layer, the above-mentioned heat conduction is further improved and the operation of the heat sensitive element 20 is accelerated. It will be done.

Furthermore, in addition to increasing the efficiency of heat conduction from the structure described above, the position of the recess 21 is set at the position where the temperature of the hot water is the highest. Since the length is short, it is higher than the part facing the outlet pipe 18, and therefore the temperature of the heat sensitive element 20 can be detected faster.

Furthermore, since the lower surfaces of the heat exchange elements 13, 131 are set at a higher position than the inlet pipe 19 via the curved portion 16, during dry heating, the little remaining hot water moves to the inlet pipe 19 side, and the heat exchange elements 13, 13
Since it does not remain in the lower part of the heat sensitive element 20 in the heating width direction L, the wall surface temperature tends to rise, which also causes the operation of the heat sensitive element 20 to be accelerated.

In this way, the present invention provides a heat exchange element on both wall surfaces of the heat exchange element located at the end, at the end opposite to the end where the inlet/outlet pipe is located, and opposite to the upper position in the heating length direction. Since the heat-sensitive element for preventing dry heating is installed in the concave part, detection can be made at an extremely high temperature position, and the operation of the heat-sensitive element can be accelerated.

In addition, the uneven parts are in contact with each other through small protrusions provided on the convex parts, and the height of the recessed parts is made higher than the outer surface of the opposing wall to narrow the gap between the uneven parts.
Normally when there is water in the heat exchanger, there is no abnormal temperature rise in the concave part, and heat is conducted properly.On the other hand, even during abnormal heating such as when the heat is being heated dry, heat transfer is quick and accurate, which improves the operation of the heat-sensitive element. You can make it even faster.

[Brief explanation of the drawing]

1, 2, and 3 show the heat exchanger of each embodiment in the conventional example, and FIG. 1 is a cross-sectional view, and FIG.
The figure is a plan view with main parts cut away, and FIG. 3 is a front view.
FIG. 4 is a plan view showing an embodiment of the heat exchanger of the present invention, FIG. 5 is a side view, and FIG. 6 is a sectional view of the main part. 13,131...heat exchange element, 15...interval,
20... Heat sensitive element, 21... Concave portion, 22... Convex portion, 23... Small convex portion, 24... Gap.

Claims (1)

[Claims] 1 A plurality of heat exchange elements are arranged side by side with intervals through which the combustion gas passes, and a heating element is placed on both walls of the heat exchange element located at the end, and at the end opposite to the side where the inlet/outlet pipe is located. A concave part facing each other and a convex part protruding from the gap side are provided at the upper part in the length direction, a heat-sensitive element for preventing dry heating is attached to this concave part, and the concave part and the convex part are brought into contact with each other in part, and the height of the concave part is adjusted. A heat exchanger that is made higher than the outer surface of a wall with convex portions and narrows the gap between the concave and convex portions.