JP2013217540A - Heat exchanger and hygienic cleaning toilet seat provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger with stable heat exchange performance and excellent scale resistance.SOLUTION: In a heat exchanger 10, a heat exchange conduit 25, for heat-exchanging water flowing from a water inlet port 23a by using a surface of a heater 20 incorporating a heating resistor as a heat transfer surface and directing the water to flow to a water outlet port 23b, is composed of a flow passage forming member in which an edge 45 of a partition rib 31 having spring properties and formed by bending a metal plate tightly contacting an inner wall surface of a casing 23 at a plurality of places contacts a surface of a heater 20 incorporating the heating resistor. This can prevent leakage from the edge of the partition rib which might block forcible convection heat exchange, does not generate local boiling on a surface of the heater, and can lower temperature of the heater surface, to provide a heat exchanger with stable heat exchange performance and excellent scale resistance and a hygienic cleaning device with long lifetime.

Description

  The present invention relates to an instantaneous heating type heat exchanger used in a sanitary washing apparatus that can wash a human body part with warm water after a stool.

  The sanitary washing device is provided with a heat exchanger for bringing the wash water to an appropriate temperature when washing the human body part after the toilet with water. There are various types of heat exchangers, and one of them is a flat plate as disclosed in Patent Document 1. This is because a flat heater is accommodated vertically in a rectangular parallelepiped casing having a small thickness dimension, and the two flow upwards while meandering horizontally along both the heat transfer surfaces of the flat heater. The road is formed. Then, the cleaning water is heated to an appropriate temperature by allowing the cleaning water to flow along each flow path while the flat heater is being driven. In the case of such a heat exchanger disclosed in Patent Document 1, since the cross-sectional area of the flow path is small, the flow rate of cleaning water can be increased and the heat transfer rate can be increased, and the heat transfer coefficient can be increased. There is an advantage that you can.

Japanese Patent Laid-Open No. 10-220876 (refer to FIG. 2 in particular)

However, the heat exchanger for instantaneous water heating that heats the cleaning water of the sanitary cleaning device has a maximum flow rate of about 0.5 L / min and heats up to 40 ° C. hot water with 5 ° C. water input. It requires about ^{1200W, 20W / cm 2 ~50W /} cm 2 of about watt density is relatively large heater is being used as a watt density of the heater.
And in the conventional heat exchanger, since the maximum flow rate passing through the heat exchanger is as low as about 0.5 L / min, the stability of the operation in the heat exchanger and further when used in a hard water area There were problems such as adhesion of scale to the heater surface.

  Moreover, in order to stabilize heat exchange conditions, it is necessary to perform heat exchange by forced convection heat transfer not involving boiling heat transfer. For this purpose, as a method of ensuring the flow velocity on the heater surface in the heat exchanger, a flat plate heater is used, and a partition rib is provided on the wall of the heat exchanger in the vicinity of the flat plate heater. There has been a method of promoting heat transfer by forced convection heat exchange between flowing water and a flat heater surface by increasing the flow rate of flowing water through meandering channels formed by partitioning.

  The conventional heat exchanger using this flat heater promotes heat transfer on the heater surface by inducing forced convection on the heater surface and flowing uniformly on the heater surface while ensuring a flow velocity. The gap between the main surface which is a meandering heat exchange channel composed of the partition rib and the heater surface and the tip of the partition rib so as to leak into the adjacent meandering channel. There was a problem that forced convection heat exchange was hindered by the leakage flow flowing through the.

As a specific example of the above problem, in the conventional heat exchanger, the partition rib formed close to the flat plate heater of the ceramic heater is formed by resin injection molding integrally with the casing of the heat exchanger. Due to dimensional accuracy including heat shrinkage and molding warpage, the gap between the tip of the partition rib and the flat heater surface is not uniform, and temperature unevenness occurs on the flat heater surface during heat exchange. As a result, scale is likely to be generated and adhered to locally hot parts of the surface of the flat heater. Especially in the water quality area where the hardness is high, if the scale adheres to the surface of the flat heater, the temperature difference on the surface of the ceramic heater May increase and cause cracks in the ceramic heater.

  In addition, in order to reduce the leakage flow flowing through the gap between the heater surface and the tip of the partition rib, which is an impediment to the forced convection heat exchange described above, the partition rib dimensions are set such that the tip of the partition rib is in close contact with the heater surface. In this case, the portion where the tips of the resin partition ribs are in close contact with each other is likely to be locally heated due to the heat of the surface of the ceramic heater being insulated, resulting in further promotion of cracking of the ceramic heater. In addition, in this case, the tips of the partition ribs made of resin that is vulnerable to high temperatures may be damaged by heat, and the problem cannot be solved.

  The present invention solves the above-mentioned conventional problems, and local boiling does not occur on the surface of the heater, and by reducing the temperature of the heater surface, heat exchange with stable heat exchange performance and excellent scale resistance is achieved. The purpose is to provide a vessel.

In order to solve the conventional problems, the heat exchanger of the present invention is
A casing having a water inlet and a water outlet;
A heater with a built-in heating resistor;
A heat exchange flow path that guides the fluid flowing in from the water inlet to heat exchange with the surface of the heater as a heat transfer surface and flows to the water outlet;
The heat exchange flow path is formed by a flow path forming member in which tips of partition ribs having a spring property formed by bending a plurality of portions of a metal plate in close contact with the inner wall surface of the casing are in contact with the surface of the heater. It is characterized by comprising (claim 1).

  As a result, the water flowing in from the water inlet of the casing is heated while flowing through the heat exchange channel with the surface of the heater as the heat transfer surface, and the temperature of the cleaning water, which is a fluid, gradually increases as it approaches the water outlet. The heat exchange flow path is constituted by a flow path forming member in which the tip end portion of a partition rib having a spring property formed by bending a plurality of portions of a metal plate in close contact with the inner wall surface of the casing is in contact with the surface of the heater. As a result, the leakage flow from the tip of the partition rib, which inhibits forced convection heat exchange, can be prevented, local boiling does not occur on the heater surface, and the temperature of the heater surface is reduced. Therefore, stable heat exchange performance and heat exchange excellent in scale resistance are possible.

  In this case, since the flow path forming member is a metal plate, even if the tip of the partition rib having a spring property contacts the heat transfer surface of the heater surface, the heat conductivity is high and the heat of the heater is transmitted to the metal partition rib. Furthermore, it is transmitted to water. Therefore, there is no problem that the heat on the surface of the heater is insulated as in the case of resin partition ribs, and the heat transfer efficiency is increased.

  In addition, the flow path forming member is a metal plate, and the tip of the partition rib having spring properties is in contact with the heat transfer surface of the heater surface, so even if there is some variation in the dimensions of the heater or casing, The leading end portion of the partition rib can surely contact the heat transfer surface of the heater surface, and excessive load stress to the heater can be prevented by bending the partition rib due to the spring property.

  Further, the heater is a flat plate heater, and the heat exchange flow path extends from the lower water inlet to the upper portion along each of the flow path forming members in contact with the heat transfer surfaces on the front and back of the flat plate heater. You may form in the two meandering flow paths extended to the water outlet (Claim 2).

  As a result, the heat of the flat heater is transferred to the washing water that flows in contact with both sides of the front and back, and heat exchange with high thermal efficiency is possible with almost no waste of heat loss. Because it can be used, it can be made compact and compact, and the length of the flow path can be increased by the meandering flow path and the flow velocity can be increased, so that the thickness of the boundary layer between the heater surface and washing water is made thinner, and the heat transfer efficiency Since the temperature of the heater surface is also lowered, the local boiling phenomenon can be further suppressed, and the effect of preventing the formation and adhesion of scale can be further enhanced.

  The flow path forming member may be formed by bending a plurality of portions of a stainless steel plate.

  A stainless steel thin plate has springiness and corrosion resistance, and can supply clean hot water over a long period of time.

  Further, in the heat exchanger according to the present invention, the flat plate heater has a heat generation density facing a heat exchange channel on the side close to the water inlet, and a heat generation density facing the heat exchange channel on the side close to the water inlet. It may be formed smaller (claim 4).

  In this case, the fluid flowing in from the water inlet of the casing is heated by the heat transfer surface on the surface of the flat heater while flowing through the heat exchange flow path meandering on the surface of the flat heater, and the fluid flows as it approaches the water outlet. The temperature gradually increases.

  The surface temperature of the flat heater facing the heat exchange channel near the water inlet tends to become high due to the high heat generation density of the flat heater, but heat is applied to the low-temperature fluid that has not yet been heated. Because many are deprived (that is, the value of the subcool is large) and the flow path is thin and the flow velocity is high, the heat transfer rate is high and the local boiling phenomenon does not occur.

  On the other hand, the surface temperature of the flat heater facing the heat exchange channel on the side close to the water outlet is higher than that on the side close to the water inlet because the fluid in contact with the surface of the flat heater has already been heated. It is easy to become.

  However, the heat taken away by the fluid from the surface of the flat heater is reduced and the subcool value is reduced, but the flat heater has a lower heat generation density on the side near the water outlet than that on the side near the water inlet. Since it is formed, the temperature is not high enough to cause local boiling.

  In this way, the flat heater is formed so that the heat generation density facing the heat exchange flow path on the side close to the water outlet is smaller than the heat generation density facing the heat exchange flow path on the side close to the water inlet. Even at the boundary surface between the flat heater and water near the outlet where the temperature rises, it is possible to prevent the formation and adhesion of scales by preventing high temperatures that cause local boiling, and long life Heat exchanger can be provided.

  On the other hand, the heat generation density of the flat heater facing the heat exchange channel on the side close to the water inlet where the temperature of the fluid (water) is relatively low and the flow velocity is higher than that on the side near the water outlet Therefore, the heat exchange efficiency in the vicinity of the heat exchange flow path near the water inlet can be improved.

  If the local distribution of heat generation density is uniform over the entire surface of the heat transfer surface with a normal flat heater, the temperature close to the water outlet of the flat heater is the highest temperature, and a scale is first generated in this area. Is done.

  However, the heat generation density distribution of the flat heater is set so that the vicinity of the heat exchange channel near the water outlet is smaller than the vicinity of the heat exchange channel near the water inlet. The heat flux of the exchanger is high at locations where the heat generation density of the heater is high, and low at locations where the heat generation density is low.Therefore, the heat transfer surface temperature is made uniform, the temperature rises locally, and the scale appears there. It can suppress adhering.

  By adopting such a configuration, heat is transferred to the washing water flowing in contact with the flat heater, heat exchange with high thermal efficiency with almost no waste of heat dissipation can be achieved, a compact and compact scale can be attached. Can be suppressed.

  Further, in the heat exchanger according to the present invention, the flat heater is a ceramic heater including a ceramic base, a heating resistor formed by pattern printing a resistor on the ceramic base, and an electrode, The heater line width of the printed pattern may be formed so that the portion facing the heat exchange flow path on the side close to the water outlet is thicker than the portion facing the heat exchange flow path on the side close to the water inlet ( Claim 5).

  By adopting such a configuration, the larger the line width of the printed pattern as the heating resistor, the smaller the electrical resistance when a current is passed, and the smaller the amount of heat generated. Therefore, the portion facing the heat exchange channel on the side close to the water inlet with the narrow line width of the printed pattern has a large amount of heat generation (that is, the heat generation density is large), and the part near the water outlet with the large line width of the printed pattern. The portion facing the heat exchange flow path becomes a ceramic heater that generates a small amount of heat (that is, a low heat generation density).

  Therefore, even at the boundary surface between the ceramic heater and the fluid in the portion facing the heat exchange flow path on the side close to the outlet where the temperature of the fluid becomes high, it is suppressed that the temperature becomes high enough to cause a local boiling phenomenon. , Scale formation and adhesion can be prevented. As a result, it is possible to maintain high heat exchange efficiency and to realize a long-life heat exchanger that can prevent cracking in a heater using ceramics that has a small heat capacity compared to metal but is easily cracked. be able to.

  Further, in the heat exchanger according to the present invention, the flat heater is a ceramic heater including a ceramic base, a heating resistor formed by pattern printing a resistor on the ceramic base, and an electrode, The gap between the lines of the printed pattern may be formed so that the portion facing the heat exchange flow path closer to the water outlet is wider than the portion facing the heat exchange flow path closer to the water inlet. Good (Claim 6).

  By adopting such a configuration, the portion facing the heat exchange channel on the side close to the water inlet where the gap between the printed pattern lines is narrow generates a large amount of heat (that is, the heat generation density is large), and the printed pattern lines A portion facing the heat exchange channel on the side close to the water outlet with a wide gap between them becomes a ceramic heater with a small amount of heat generation (that is, a small heat generation density). Therefore, for the same reason as described above, scale generation and adhesion can be prevented, and cracking of the ceramic heater can be prevented, and a long-life heat exchanger can be realized.

  Moreover, the sanitary washing apparatus provided with the heat exchanger according to any one of claims 1 to 6 is characterized in that the heat exchanger is small and stable, has excellent heat exchange performance and scale resistance, and has a long life. The sanitary washing device itself can be downsized, can be easily installed in a narrow toilet space, and can be used in hard water areas by preventing the formation and adhesion of scales in the heat exchanger. The apparatus can be realized, the cleaning nozzle can be prevented from being clogged with scale fragments, and a sanitary cleaning apparatus with a long life can be obtained (claim 7).

  ADVANTAGE OF THE INVENTION According to this invention, the local boiling does not generate | occur | produce on a heater surface, and the heat exchanger excellent in the stable heat exchange performance and scale resistance can be provided by reducing the temperature of a heater surface.

The external appearance perspective view which shows the sanitary washing apparatus provided with the heat exchanger which concerns on embodiment of this invention The front view which shows the external appearance structure of the heat exchanger which concerns on Embodiment 1 of this invention. Right side view of the heat exchanger shown in FIG. Sectional drawing in the AA line of the heat exchanger shown in FIG. 2 is an exploded perspective view of the heat exchanger shown in FIG. The front view before setting the partition rib of the heat exchanger shown in FIG. 2 to a 1st casing member The front view after setting the partition rib of the heat exchanger shown in FIG. 2 to the 1st casing member The front view before setting the partition rib of the heat exchanger shown in FIG. 2 to a 2nd casing member The front view after setting the partition rib of the heat exchanger shown in FIG. 2 to the 2nd casing member The top view which shows the example of a pattern of the resistor formed in the flat heater of the heat exchanger shown in FIG. The top view which shows another example of a pattern of the resistor formed in the flat heater of the heat exchanger shown in FIG. The perspective view after setting the partition rib of the heat exchanger shown in FIG. 2 to the 2nd casing member 12 is a partially enlarged perspective view of FIG. The perspective view which illustrates the partition rib shape of the heat exchanger which concerns on embodiment of this invention Graph of the result of simulating the effect of the tip clearance of the partition rib Graph of the result of simulating the effect of the tip clearance of the partition rib Graph of the result of simulating the effect of the tip clearance of the partition rib Graph of the result of simulating the effect of the tip clearance of the partition rib Graph of the results of experiments on the effect of the tip clearance of the partition rib A graph schematically showing the experimental results of FIG.

  In the first invention, a casing having a water inlet and a water outlet, a heater incorporating a heating resistor, and fluid flowing in from the water inlet are heat-exchanged with the surface of the heater as a heat transfer surface to the water outlet. A heat exchange flow path that guides the flow to flow, and the heat exchange flow path is formed by bending a plurality of portions of a metal plate that is in close contact with the inner wall surface of the casing, and the tip end portion of a partition rib having a spring property Is constituted by the flow path forming member in contact with the surface of the heater, so that water flowing in from the water inlet of the casing is heated while flowing through the heat exchange flow path with the surface of the heater as the heat transfer surface, and approaches the water outlet. Accordingly, the temperature of the washing water, which is a fluid, gradually increases. The heat exchange flow path is constituted by a flow path forming member in which the tip end portion of a partition rib having a spring property formed by bending a plurality of portions of a metal plate in close contact with the inner wall surface of the casing is in contact with the surface of the heater. As a result, the leakage flow from the tip of the partition rib, which inhibits forced convection heat exchange, can be prevented, local boiling does not occur on the heater surface, and the temperature of the heater surface is reduced. Therefore, stable heat exchange performance and heat exchange excellent in scale resistance are possible.

In this case, since the flow path forming member is a metal plate, even if the tip of the partition rib having a spring property contacts the heat transfer surface of the heater surface, the heat conductivity is high and the heat of the heater is transmitted to the metal partition rib. Furthermore, it is transmitted to water. Therefore, there is no problem that the heat on the surface of the heater is insulated as in the case of resin partition ribs, and the heat transfer efficiency is increased.

  In addition, the flow path forming member is a metal plate, and the tip of the partition rib having spring properties is in contact with the heat transfer surface of the heater surface, so even if there is some variation in the dimensions of the heater or casing, The leading end portion of the partition rib can surely contact the heat transfer surface of the heater surface, and excessive load stress to the heater can be prevented by bending the partition rib due to the spring property.

  In the second invention, in particular, the heater of the first invention is a flat plate heater, and the heat exchange flow path is along each of the flow path forming members in contact with the heat transfer surfaces on the front and back of the flat plate heater. By being formed in two meandering channels extending from the lower water inlet to the upper water outlet, the heat of the flat heater is transferred to the wash water flowing in contact with both the front and back surfaces to dissipate heat. Heat exchange with high thermal efficiency with almost no loss is possible, and both the front and back sides of the flat heater can be used as the heat transfer area, so it can be made compact and compact, and the meandering flow path can increase the flow path length and speed. Since the thickness of the boundary layer between the heater surface and the cleaning water acts to be thinner, the heat transfer efficiency is improved and the temperature of the heater surface is also lowered. With generation It is possible to enhance the effect of preventing.

  In the third invention, in particular, the flow path forming member of the first invention or the second invention is formed by bending a plurality of portions of a stainless steel plate, so that it has excellent corrosion resistance, a long life, and a long period of time. Can supply clean hot water.

  According to a fourth aspect of the present invention, in particular, the flat heater of the second aspect or the third aspect of the invention is a heat exchange flow path whose heat generation density facing the heat exchange flow path on the side close to the water outlet is on the side close to the water inlet. It is set as the structure smaller than the heat generation density which faced.

  In this case, the fluid flowing in from the water inlet of the casing is heated by the heat transfer surface on the surface of the flat heater while flowing through the heat exchange flow path meandering on the surface of the flat heater, and the fluid flows as it approaches the water outlet. The temperature gradually increases.

  The surface temperature of the flat heater facing the heat exchange channel near the water inlet tends to become high due to the high heat generation density of the flat heater, but heat is applied to the low-temperature fluid that has not yet been heated. Because many are deprived (that is, the value of the subcool is large) and the flow path is thin and the flow velocity is high, the heat transfer rate is high and the local boiling phenomenon does not occur.

  On the other hand, the surface temperature of the flat heater facing the heat exchange channel on the side close to the water outlet is higher than that on the side close to the water inlet because the fluid in contact with the surface of the flat heater has already been heated. It is easy to become.

  However, the heat taken away by the fluid from the surface of the flat heater is reduced and the subcool value is reduced, but the flat heater has a lower heat generation density on the side near the water outlet than that on the side near the water inlet. Since it is formed, the temperature is not high enough to cause local boiling.

  In this way, the flat heater is formed so that the heat generation density facing the heat exchange flow path on the side close to the water outlet is smaller than the heat generation density facing the heat exchange flow path on the side close to the water inlet. Even at the boundary surface between the flat heater and water near the outlet where the temperature rises, it is possible to prevent the formation and adhesion of scales by preventing high temperatures that cause local boiling, and long life Heat exchanger can be provided.

  On the other hand, the heat generation density of the flat heater facing the heat exchange flow path on the side close to the water inlet is higher than the heat exchange flow path on the side close to the water outlet, where the fluid temperature is relatively low. Therefore, the heat exchange efficiency in the vicinity of the heat exchange flow path near the water inlet can be improved.

  If the local distribution of heat generation density is uniform over the entire surface of the heat transfer surface with a normal flat heater, the temperature close to the water outlet of the flat heater is the highest temperature, and a scale is first generated in this area. Is done.

  However, the heat generation density distribution of the flat heater is set so that the vicinity of the heat exchange channel near the water outlet is smaller than the vicinity of the heat exchange channel near the water inlet. The heat flux of the exchanger is high at locations where the heat generation density of the heater is high, and low at locations where the heat generation density is low.Therefore, the heat transfer surface temperature is made uniform, the temperature rises locally, and the scale appears there. It can suppress adhering.

  By adopting such a configuration, heat is transferred to the washing water flowing in contact with the flat heater, heat exchange with high thermal efficiency with almost no waste of heat dissipation can be achieved, a compact and compact scale can be attached. Can be suppressed.

  The fifth invention is a ceramic heater comprising a ceramic substrate, a heating resistor formed by pattern printing a resistor on the ceramic substrate, and an electrode. The heater line width of the printed pattern is such that the portion facing the heat exchange flow path nearer to the water outlet is thicker than the portion facing the heat exchange flow path closer to the water inlet.

  By adopting such a configuration, the larger the line width of the printed pattern as the heating resistor, the smaller the electrical resistance when a current is passed, and the smaller the amount of heat generated. Therefore, the portion facing the heat exchange channel on the side close to the water inlet with the narrow line width of the printed pattern has a large amount of heat generation (that is, the heat generation density is large), and the part near the water outlet with the large line width of the printed pattern. The portion facing the heat exchange flow path becomes a ceramic heater that generates a small amount of heat (that is, a low heat generation density).

  Therefore, even at the boundary surface between the ceramic heater and the fluid in the portion facing the heat exchange flow path on the side close to the outlet where the temperature of the fluid becomes high, it is suppressed that the temperature becomes high enough to cause a local boiling phenomenon. , Scale formation and adhesion can be prevented. As a result, it is possible to maintain high heat exchange efficiency and to realize a long-life heat exchanger that can prevent cracking in a heater using ceramics that has a small heat capacity compared to metal but is easily cracked. be able to.

  The sixth invention is a ceramic heater comprising a ceramic substrate, a heating resistor formed by pattern printing a resistor on the ceramic substrate, and an electrode. The gap between the lines of the printed pattern is formed so that the portion facing the heat exchange channel closer to the water outlet is wider than the portion facing the heat exchange channel closer to the water inlet. is there.

  By adopting such a configuration, the portion facing the heat exchange channel on the side close to the water inlet where the gap between the printed pattern lines is narrow generates a large amount of heat (that is, the heat generation density is large), and the printed pattern lines A portion facing the heat exchange channel on the side close to the water outlet with a wide gap between them becomes a ceramic heater with a small amount of heat generation (that is, a small heat generation density). Therefore, for the same reason as described above, scale generation and adhesion can be prevented, and cracking of the ceramic heater can be prevented, and a long-life heat exchanger can be realized.

The sixth aspect of the invention is particularly a sanitary washing apparatus provided with the heat exchanger of the first to sixth aspects of the invention.
The heat exchanger has a small and stable heat exchange performance and scale resistance, and has a long service life, so the sanitary washing device itself can be downsized and installed easily in a narrow toilet space. By preventing the generation and adhesion of scale in the heat exchanger, it is possible to realize a sanitary washing device that can be used in hard water areas, prevent clogging of scale debris into the washing nozzle, and make it a long-life sanitary washing device. it can.

  Hereinafter, a heat exchanger according to an embodiment of the present invention will be described with reference to the drawings, taking an example applied to a sanitary washing device. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
[Sanitary washing equipment]
FIG. 1 is an external perspective view showing a sanitary washing apparatus including a heat exchanger according to an embodiment of the present invention. As shown in FIG. 1, the sanitary washing device 1 is disposed on the upper surface of the toilet 2, and includes a main body 3, a toilet seat 4, a toilet lid 5, an operation unit 6, and the like. Of these, the main body 3 is disposed on the rear side (back side as viewed from the seated user) of the toilet seat 4, and in a horizontally long and hollow housing 3a, a cleaning unit, a drying unit (not shown), and In addition to a control unit that controls these operations, a heat exchanger 10 (illustrated by a broken line) according to the present embodiment is accommodated. In this heat exchanger 10, tap water (fluid, liquid, washing water) is introduced from a water supply facility attached to the building where the toilet 2 is installed, and is heated to an appropriate temperature inside. When the user operates the operation unit 6 to perform a predetermined input, the cleaning unit is driven, and cleaning water is jetted from the nozzles of the cleaning unit to the human body part in a shower shape. ing.

[Heat exchanger]
2-5 is drawing which shows the structure of the heat exchanger 10 (10), FIG. 2 is a front view which shows an external appearance structure, FIG. 3 is a right view of FIG. 2, FIG. 4 is A- of FIG. Cross-sectional views along line A are shown. As shown in FIGS. 2 to 4, the heat exchanger 10 is configured to have a flat plate-like appearance having a small thickness and a substantially rectangular shape when viewed from the front. Shaped heater 20, first casing member 21 disposed opposite to one surface (first heat transfer surface) 20a, and second casing member 22 disposed opposite to the other surface (second heat transfer surface) 20b. And a casing 23 that accommodates these and has a water inlet 23a and a water outlet 23b. Of these, the flat heater 20 is made of ceramic, and the first casing member 21 and the second casing member 22 are made of reinforced ABS resin in which glass fiber is compounded with ABS resin.

  In the following description, unless otherwise specified, a state in which such a heat exchanger 10 is vertically placed so that the heat transfer surface of the flat heater 20 is parallel to the vertical direction will be described. Further, as shown in FIG. 2, the vertical direction is the Z direction, the direction perpendicular to this and parallel to the heat transfer surface of the flat plate heater 20 is the X direction, and the direction perpendicular to both of these two directions (the first direction) The direction perpendicular to the heat transfer surface 20a) is taken as the Y direction.

  As shown in FIGS. 3, 4, and 5, the heat exchange flow path 25 includes a plurality of portions of the metal plate that are in close contact with the inner wall surface (30 a, 40 a) of the casing 23 (first casing member 21, second casing member 22). A distal end portion 45 of a partition rib 31 having a spring property formed by bending is formed by a flow path forming member 41 in contact with the surface of the flat heater 20.

  The plurality of partition ribs 31 form a heat exchange channel 25 that meanders from the inlet channel 25a to the outlet channel 25b.

In addition, a wall-like flange portion 32 is provided around the periphery of the base portion 30 of the first casing member 21, and the flange portion 32 has a predetermined dimension in a direction close to the second casing member 22. It is extended. An engaging groove 33 that circulates along the flange portion 32 is formed at the distal end portion of the flange portion 32.

  On the other hand, a wall-like flange portion 42 is also provided around the periphery of the base portion 40 of the second casing member 22, and the flange portion 42 has a predetermined dimension in a direction away from the first casing member 21. It is extended. The front end portion of the flange portion 42 is folded back toward the first casing member 21, and an engaging protrusion 43 that circulates along the flange portion 42 is formed at the end portion.

  The first casing member 21 is externally fitted to the second casing member 22 such that the inner wall surface 30a faces the inner wall surface 40a of the second casing member 22. More specifically, the flange portion 32 of the first casing member 21 is externally fitted to the flange portion 42 of the second casing member 22, and the engagement of the second casing member 22 is further engaged with the engagement groove 33 of the first casing member 21. The mating protrusion 43 is inserted (for example, the engaging protrusion 43 is fixed to the engaging groove 33 by ultrasonic welding). As a result, the first casing member 21 and the second casing member 22 are joined in a liquid-tight manner, and the heat exchanger channel 25 is formed by the internal flat heater 20 and the channel forming member 41.

  FIG. 5 is an exploded perspective view showing the state of the parts before the flat plate heater 20, the flow path forming member 41, and the first casing member 21 and the second casing member 22 are ultrasonically welded. When the first casing member 21 and the second casing member 22 are ultrasonically welded, flow paths are formed in the first casing member 21 and the second casing member 22, respectively, as shown in FIGS. With the member 41 set in advance, ultrasonic welding is performed by sandwiching the flat heater 20 between the flow path forming members 41 having the partition ribs 31 having a spring property, and thereafter, the flat heater 20 and the casing 23 are connected to each other. The assembly procedure is to seal the gap with a sealing material.

  6 and 7, FIG. 6 shows a state before the flow path forming member 41 is set on the first casing member 21, and FIG. 7 shows a state after the flow path forming member 41 is set on the first casing member 21. It is.

  The position where the small protrusion 21t of the first casing member 21 and the small hole 41h of the flow path forming member 41 fit as shown in FIG.

  Further, in the state where the flow path forming member 41 is set in the first casing member 21 as shown in FIG. 7, the end portions of the plurality of partition ribs 31 formed in the flow path forming member 41 are alternately arranged. A meandering flow path that is the heat exchange flow path 25 as shown by the arrow is formed in alignment with the position of the side rib 21 s of the first casing member 21.

  8 and 9, FIG. 8 shows a state before setting the flow path forming member 41 on the second casing member 22, and FIG. 9 shows a state after setting the flow path forming member 41 on the second casing member 22. It is.

  From the state where the flow path forming member 41 is placed on the second casing member 22 as shown in FIG. 8, the small protrusion 22t of the second casing member 22 and the flow path are slid by sliding the flow path forming member 41 as shown in FIG. Since the flow path forming member 41 is fitted and locked to the locking protrusion 22k of the second casing member 22 at the position where the small hole 41h of the forming member 41 is fitted, the flow is not generated when the ultrasonic welding is assembled. Even if the path forming member 41 is in the downward posture, the flow path forming member 41 set in the second casing member 22 does not fall.

Further, in the state where the flow path forming member 41 is set in the second casing member 22 as shown in FIG. 9, the end portions of the plurality of partition ribs 31 formed on the flow path forming member 41 are alternately arranged. A meandering flow path is formed which becomes the heat exchange flow path 25 as indicated by the arrow in alignment with the position of the side rib 22s of the second casing member 22.

  In addition, in FIG. 12, the state by which the flow-path formation member 41 was set to the 2nd casing member 22 of FIG. 9 is shown with the perspective view so that it may be understood more easily. Further, FIG. 13 is an enlarged partial enlarged view of a portion surrounded by a solid circle in FIG.

  As shown in FIGS. 2 and 3, a water inlet 23a is provided at the lower end of the casing 23 in the X direction, and a water outlet 23b is provided at the upper end of the casing 23. The liquid flowing in from the water inlet 23a is heated by the flat heater 20 while passing through the meandering heat exchange passage 25 shown in FIGS. 4, 7, 9, and 12, and the water outlet. 23b flows out from 23b.

  FIG. 10 is a plan view showing a pattern example of a resistor formed on the flat heater 20 of the heat exchanger shown in FIG. As shown in FIG. 10, the flat heater 20 has a structure in which a resistor (heater wire) pattern 20p is printed on a ceramic substrate 20k. The resistor pattern 20p is configured such that the heater line width 20s is narrow at the portion near the water inlet 23a of the flat heater 20 and the heater line width 20s is thick at the portion near the water outlet 23b. is there.

  In short, according to the resistor pattern 20p, the heater line width 20s becomes narrower toward the lower part of the flat heater 20 near the water inlet 23a and the resistance value becomes higher, and the heater line width 20s becomes closer to the upper part near the water outlet 23b. The resistance value decreases as the thickness increases. In other words, in the flat heater 20, the heat generation density of the portion facing the outlet-side flow path on the side close to the water outlet 23b is lower than the heat generation density of the portion facing the inlet-side flow path on the side close to the water inlet 23a. It is formed as follows.

  FIG. 11 is a plan view showing another pattern example of the resistor formed on the flat heater 20 of the heat exchanger shown in FIG. As in the case of the resistor (heater wire) pattern 20p shown in FIG. 11, the flat plate heater 20 has a structure in which the resistor (heater wire) pattern 20p is printed on the ceramic substrate 20k. ing.

  On the other hand, in the case of the resistor pattern 20p shown in FIG. 11, the adjacent heater wire interval 20h is narrow in the portion near the water inlet 23a of the flat heater 20, and the heater wire in the portion near the water outlet 23b. The interval 20h is configured to be wide. That is, in the flat heater 20, the heater line interval 20h is narrower and the heat generation density is higher at the lower part near the water inlet 23a, and the heater line interval 20h is wider and the heat generation density is lower at the upper part near the water outlet 23b. Is formed.

  Next, between the heat exchanger flow path 25 flowing meandering in the heat exchanger 10 and the flow path adjacent to the meander flow path between the tip of the partition rib 31 and the flat plate heater 20. The result of analyzing the relationship between the flow rate of the leakage amount flowing through the gap will be described. First, as shown in FIG. 12, the leakage flow rate (Qleak) and the heat exchange flow path when the rib pitch of the partition rib 31 forming the meandering heat exchange flow path 25 is changed to P and the rib height H1 of the partition rib 31 is changed to four types. The results of simulating the effect of the tip clearance of the partition rib 31 at a flow rate (Qmain) of 25 are shown in FIG. 15, FIG. 16, FIG. 17, and FIG.

Here, the simulation was performed by setting the flow rate of the heat exchange flow path 25 which is a flow rate range to be normally used from 0.16 mm / sec to 1.25 mm / sec. The influence of the leakage flow rate (Qleak) tends to increase as the cross-sectional area of the heat exchange channel 25 decreases and the flow rate increases, and the leakage flow rate is 50 cc / min or less, which is 10% of the total flow rate of 500 cc / min. In order to achieve this, it was necessary to set the tip clearance to be at least 0.15 mm or less.

  Next, in order to grasp the influence of this tip clearance with an actual heat exchanger, the flow rate is 500 cc / s with the heat exchanger with the rib pitch P of the partition rib 31 = 7 mm and the rib height H1 of the partition rib 31 = 1.9 mm. The heater wire temperature was measured at a water inlet temperature of 5 ° C. for min, the heat exchanger was made of a transparent material, and the heat exchange state was visualized and observed.

  The experimental results are shown in FIG. From the experimental results, it is shown that when the gap is reduced from about 0.2 mm to 0.05 mm, there is a region where the heater wire temperature rapidly decreases, and the leakage flow rate is greatly decreased in this region.

  FIG. 20 shows the average heat transfer coefficient as a heat exchanger evaluated from the heater wire temperature, and schematically shows the ratio between forced convection heat transfer and boiling heat transfer. When the gap is around 0.05 mm, local boiling in the heat exchanger is not recognized, and forced convection heat transfer is assumed in almost the entire region, resulting in a stable hot water operation.

  When the gap is around 0.15 mm, some local boiling is observed in the heat exchanger, but boiling heat transfer occurs in addition to forced convection heat transfer, but the tapping operation is stable. Stable hot water is possible.

  However, when the gap is around 0.3 mm, boiling occurs in the heat exchanger, the influence of boiling heat transfer is increased, and the flow becomes unstable.

  Therefore, the state of heat transfer changes due to the change in the gap at the tip of the partition rib, and at least the gap (tip clearance) between the tip of the partition rib 31 and the flat heater 20 is suppressed to 0.15 mm or less, thereby stabilizing the hot water supply. More preferably, by suppressing the gap (tip clearance) to about 0.05 mm to 0.1 mm, the scale resistance in the hard water region can be improved.

  As described above, by making the gap (tip clearance) between the tip of the partition rib 31 and the flat heater 20 about 0.05 mm to 0.1 mm, local boiling does not occur on the flat heater surface. By reducing the temperature of the heater surface, it is possible to provide a heat exchanger with stable heat exchange performance and excellent scale resistance, but the resin constituting the casing 23 constituting the outer shell of the heat exchanger Due to molding warpage of the first casing member 21 and the second casing member 22 which are molded products, welding dimension variations due to ultrasonic welding, and the like, the partition ribs 31 are connected to the first casing member 21 and the second casing member 22 in the conventional manner. When formed by integral resin molding, the clearance (tip clearance) between the tip of the partition rib 31 and the flat heater 20 is secured to 0.05 mm to 0.1 mm. It is difficult.

  Therefore, the tip of the partition rib 31 having a spring property formed by bending a plurality of portions of the metal plate in close contact with the inner wall surface (30a, 40a) of the casing 23 (first casing member 21, second casing member 22). The configuration of the present embodiment in which the heat exchange flow path 25 is formed by the flow path forming member 41 in which the portion 45 is in contact with the surface of the flat heater 20 was studied.

Between each of the first casing member 21, the second casing member 22, and the flat heater 20,
The first casing member 21, the second casing member 22 and the flat plate are formed by sandwiching the flow path forming member 41 in which a plurality of partition ribs 31 having spring properties are formed by cutting and bending the metal plate by press working. Even if there is some variation in the size of the heater 20, the tip 45 of the partition rib 31 can be surely brought into contact with the heat transfer surface of the heater surface by bending due to the spring property, and the partition rib 31 can be bent due to the spring property. As a result, almost no gap (tip clearance) between the tip 45 of the partition rib 31 and the flat heater 20 can be eliminated.

  In other words, the heat exchanger can sufficiently achieve a target clearance (gap size) of 0.05 mm to 0.1 mm between the tip of the partition rib 31 and the surface of the flat heater 20 and is 0.05 mm or less. Is also possible.

  Therefore, it is possible to prevent a leakage flow from the front end of the partition rib that obstructs forced convection heat exchange, so that local boiling does not occur on the flat heater surface and the temperature of the heater surface is reduced. Therefore, a heat exchanger having stable heat exchange performance and excellent scale resistance is possible.

  Furthermore, since the flow path forming member 41 is a metal plate, even if the tip 45 of the partition rib 31 having a spring property comes into contact with the heat transfer surface of the heater surface, the heat conductivity is high and the heat of the heater is applied to the metal partition rib 31. Is transmitted to the water. Therefore, unlike the conventional resin partition ribs, there is no problem that the heat on the heater surface is insulated and the local high temperature is generated, and scale damage due to the local high temperature and heater damage due to scale adhesion can be prevented. In addition, heat transfer efficiency to water is high and excellent heat exchange efficiency can be realized and maintained for a long time.

  Further, since the flow path forming member 41 is a metal plate and the tip 45 of the partition rib 31 having spring property is in contact with the heat transfer surface of the heater surface, even if there is some variation in the dimensions of the heater or casing, the spring property The leading edge of the partition rib can be surely brought into contact with the heat transfer surface of the heater surface by the bending due to the bending, and an excessive load stress on the heater can be prevented by the partition rib being bent by the spring property. Accordingly, it is possible to prevent a heater from being damaged by excessive stress, and to achieve a heat exchanger having stable heat exchange performance and excellent scale resistance.

  Moreover, as an example of the shape of the desirable partition rib 31, as shown in the partial enlarged view of FIG. 13, the cross section which has a circular arc in the front-end | tip part 45 of the partition rib 31 by which the metal plate 44 was cut and raised by press work and bent. It is good also as a shape. Due to the spring property due to the bending of the arc, a part of the arc abuts against the surface of the flat heater 20 while absorbing the dimensional variation, and the gap between the tip of the partition rib 31 and the flat heater 20 can be eliminated. . It should be noted that the cut-and-raised portion connected to the arc from the flat portion of the metal plate 44 is not perpendicular to the angle, for example, about 45 ° to 70 °, so that the spring property is not only the bending of the arc but also the diagonally-raised portion is also a spring. It can act as a flexible bending portion, and can cope with large dimensional variations in the casing member and the flat heater.

  Further, as another example of the shape of the partition rib 31, as shown in the partially enlarged view of FIG. In this case, the bent portion can have a spring property that allows the bent portion to bend easily by making the cross-sectional shape a substantially square shape, and the tip portion 45 abuts the surface of the flat heater 20 while absorbing the dimensional variation, and the partition rib 31. It is possible to eliminate a gap between the tip of the flat plate heater 20 and the flat heater 20. In addition, the substantially square shape is a cross-sectional shape with two diagonal sides, but even with a substantially square shape with only one diagonal side, the tip of the partition rib can be surely connected to the heat transfer surface of the heater surface by bending due to the spring property. The effect of being able to abut can be obtained.

As described above, the heat exchanger 10 according to the present embodiment includes the casing 23 provided with the water inlet 23a and the water outlet 23b, the heater 20 including the heating resistor, and the fluid flowing from the water inlet 23a on the heater surface. And a heat exchange channel 25 that guides the heat exchange surface to flow to the water outlet 23b. The heat exchange channel 25 bends a plurality of portions of the metal plate 44 that are in close contact with the inner wall surface 30a of the casing 23. The tip portion 45 of the partition rib 31 having spring property formed by the flow path forming member 41 in contact with the surface of the heater 20 makes it possible to prevent the partition rib from interfering with forced convection heat exchange. Leakage from the tip can be prevented, local boiling does not occur on the heater surface, the temperature on the heater can be lowered, and heat exchange with stable heat exchange performance and scale resistance is excellent. It is possible to provide a vessel.

  Furthermore, since the flow path forming member 41 is a metal plate, even if the tip 45 of the partition rib 31 having spring properties contacts the heat transfer surface of the heater surface, the heat conductivity is high and the heat of the heater is transmitted to the metal partition rib. And further transmitted to water. Therefore, there is no problem that the heat on the surface of the heater is insulated as in the case of resin partition ribs, and the heat transfer efficiency is increased.

  In addition, since the flow path forming member 41 is a metal plate and the tip end portion of the partition rib 31 having spring property is in contact with the heat transfer surface of the heater surface, even if there is some variation in the dimensions of the heater or the casing, it depends on the spring property. The leading end portion of the partition rib can be surely brought into contact with the heat transfer surface of the heater surface by the bending, and an excessive load stress to the heater can be prevented by the partition rib being bent by the spring property.

  Further, the heater 20 is a flat heater, and the heat exchange flow path 25 extends from the lower water inlet 23a along the flow path forming member 41 in contact with the heat transfer surfaces on the front and back of the flat heater 20. By forming the two meandering channels extending to the water port 23b, the heat of the flat heater 20 is transferred to the wash water flowing in contact with both the front and back surfaces, and the heat efficiency is almost free of heat loss. High heat exchange is possible, and both the front and back sides of the flat heater can be used as a heat transfer area, so it can be made compact and compact, and the meandering flow path can increase the flow length and increase the flow speed, so the boundary between the heater surface and cleaning water The thickness of the layer acts to become thinner, improving the heat transfer efficiency and lowering the temperature of the heater surface, thereby further suppressing the local boiling phenomenon and preventing the formation and adhesion of scale. Results can be further improved.

  Further, the flow path forming member 41 is formed by bending a plurality of portions of the stainless steel plate, so that it has excellent corrosion resistance and can supply clean hot water over a long period of time. The metal plate 44 forming the flow path forming member 41 is not limited to a stainless steel plate, and may be formed of a thin plate having excellent spring properties and thermal conductivity, such as phosphor bronze and beryllium copper.

  Further, the flat heater 20 is configured such that the heat generation density facing the heat exchange channel 25 on the side near the water outlet 23b is smaller than the heat density facing the heat exchange channel 25 on the side near the water inlet 23a. The fluid flowing in from the water inlet 23a of the casing 23 is heated by the heat transfer surface on the surface of the flat heater 20 while flowing through the heat exchange flow path 25 that meanders through the surface of the flat heater 20, and the water outlet 23b. As the temperature approaches, the temperature of the fluid gradually increases. The surface temperature of the flat heater facing the heat exchange channel on the side close to the water inlet 23a tends to become high due to the high heat generation density of the flat heater, but is heated to a low temperature fluid that has not yet been heated. Because of the large loss of heat (that is, the value of the subcool is large) and the flow rate is thin and the flow velocity is high, the heat transfer rate is high and the local boiling phenomenon does not occur.

  On the other hand, the surface temperature of the flat heater facing the heat exchange flow path on the side close to the water outlet 23b is higher than that on the side close to the water inlet 23a because the fluid in contact with the surface of the flat heater has already been heated. High temperature is likely to occur. However, although the heat deprived by the fluid from the surface of the flat heater is reduced and the subcool value is reduced, the flat heater has a lower heat generation density near the water outlet 23b than a heat generation density near the water inlet 23a. Thus, the temperature is not high enough to cause local boiling.

Thus, the flat heater is formed such that the heat generation density facing the heat exchange channel on the side close to the water outlet 23b is smaller than the heat generation density facing the heat exchange channel on the side close to the water inlet 23a. Even at the boundary surface between the flat heater and the water near the water outlet 23b where the temperature of the fluid becomes high, it is possible to prevent the formation and adhesion of scale by suppressing a high temperature that causes a local boiling phenomenon. A long-life heat exchanger can be provided. On the other hand, the heat generation density of the flat heater facing the heat exchange channel on the side close to the water inlet 23a, where the temperature of the fluid is relatively low and the flow velocity is higher than that on the side near the water outlet 23b, is Since it is enlarged, the heat exchange efficiency in the vicinity of the heat exchange flow path near the water inlet 23a can be improved.

  When the local distribution of heat generation density is uniform over the entire surface of the heat transfer surface with a normal flat heater, the temperature close to the water outlet 23b of the flat heater is the maximum temperature, and the scale is first at this portion. Generated. However, the heat generation density distribution of the flat heater 20 is set so that the vicinity of the heat exchange flow path near the water outlet 23b is smaller than the vicinity of the heat exchange flow path near the water inlet 23a. As a result, the heat flux of the heat exchanger is high at locations where the heat generation density of the heater is high and low at locations where the heat generation density is low, so that the heat transfer surface temperature is made uniform and the temperature rises locally. The scale can be prevented from adhering to the surface. By adopting such a configuration, heat is transferred to the washing water flowing in contact with the flat heater, heat exchange with high thermal efficiency with almost no waste of heat dissipation can be achieved, a compact and compact scale can be attached. Can be suppressed.

  The flat heater 20 is a ceramic heater comprising a ceramic substrate 20k, a heating resistor formed by pattern printing a resistor on the ceramic substrate 20k, and an electrode, and the heater line width of the printed pattern. 20s has a configuration in which a portion facing the heat exchange flow path on the side closer to the water outlet 23b is thicker than a portion facing the heat exchange flow path on the side close to the water inlet 23a. The larger the line width 20s of the printed pattern is, the smaller the electric resistance when a current is passed, and the smaller the amount of heat generated. Accordingly, the portion facing the heat exchange channel on the side close to the water inlet 23a where the line width 20s of the printed pattern is narrow has a large amount of heat generation (that is, the heat generation density is large), and the water outlet 23b where the line width of the printed pattern is large. The portion facing the heat exchange channel on the near side is a ceramic heater that generates a small amount of heat (that is, has a low heat generation density).

  Therefore, even at the boundary surface between the ceramic heater and the fluid in the portion facing the heat exchange flow path on the side close to the water outlet 23b where the temperature of the fluid becomes high, it is suppressed that the temperature becomes high enough to cause a local boiling phenomenon. Therefore, scale generation and adhesion can be prevented. As a result, it is possible to maintain high heat exchange efficiency and to realize a long-life heat exchanger that can prevent cracking in a heater using ceramics that has a small heat capacity compared to metal but is easily cracked. be able to.

  The flat heater 20 is a ceramic heater comprising a ceramic substrate 20k, a heating resistor formed by pattern printing a resistor on the ceramic substrate 20k, and an electrode, and between the printed pattern lines. The gap 20h has a configuration in which a portion facing the heat exchange flow path on the side closer to the water outlet 23b is formed wider than a portion facing the heat exchange flow path on the side close to the water inlet. The portion facing the heat exchange channel on the side close to the water inlet 23a where the gap 20h between the lines is narrow generates a large amount of heat (that is, the heat generation density is large), and the gap between the lines 20h of the printed pattern is wide on the water outlet 23b. The portion facing the heat exchange channel on the near side is a ceramic heater that generates a small amount of heat (that is, has a low heat generation density). Therefore, for the same reason as described above, scale generation and adhesion can be prevented, and cracking of the ceramic heater can be prevented, and a long-life heat exchanger can be realized.

In addition, in the sanitary washing apparatus as shown in FIG. 1, the heat exchanger for heating the washing water is small and stable, has excellent heat exchange performance and scale resistance, and has a long service life. Can be easily installed in a narrow toilet space, and by preventing the generation and adhesion of scales in the heat exchanger, a sanitary washing device that can be used in hard water areas can be realized. Scale pieces can be prevented from clogging, and a long-life sanitary washing device can be obtained.

  The present invention does not cause local boiling on the heater surface, and lowers the temperature of the heater surface so that it has excellent stable heat exchange performance and scale resistance, and is applied to a heat exchanger having a flat plate heater. Can do.

1 Sanitary washing device 10 Heat exchanger 20 Heater (flat heater)
20a First heat transfer surface 20b Second heat transfer surface 20h Heater wire spacing (gap between wires)
20k Ceramic substrate 20p Pattern 20s Heater line width (line width)
DESCRIPTION OF SYMBOLS 21 1st casing member 22 2nd casing member 23 Casing 23a Water inlet 23b Water outlet 25 Heat exchange flow path 25a Inlet side flow path 25b Outlet side flow path 30 Base part 30a Inner wall surface 31 Partition rib 32 Flange part 33 Engagement groove 40 Base portion 40a Inner wall surface 41 Flow path forming member 42 Flange portion 43 Engaging projection 44 Metal plate 45 Tip portion

Claims (7)

A casing having a water inlet and a water outlet;
A heater with a built-in heating resistor;
A heat exchange flow path for guiding the fluid flowing in from the water inlet to heat exchange with the surface of the heater as a heat transfer surface and flowing to the water outlet;
With
The heat exchange flow path is formed by a flow path forming member in which tips of partition ribs having a spring property formed by bending a plurality of portions of a metal plate in close contact with the inner wall surface of the casing are in contact with the surface of the heater. A heat exchanger characterized by being configured. The heater is a flat heater, and the heat exchange flow path is formed from a lower water inlet to an upper water outlet along each of the flow path forming members in contact with the heat transfer surfaces on the front and back of the flat heater. The heat exchanger according to claim 1, wherein the heat exchanger is formed in two meandering channels extending to the point. The heat exchanger according to claim 1 or 2, wherein the flow path forming member is formed by bending a plurality of portions of a stainless steel plate. 4. The flat heater is formed such that a heat generation density facing a heat exchange channel on the side close to the water outlet is smaller than a heat generation density facing a heat exchange channel on the side close to the water inlet. The heat exchanger as described in. The flat heater is a ceramic heater comprising a ceramic substrate, a heating resistor formed by pattern printing a resistor on the ceramic substrate, and an electrode, and the heater line width of the printed pattern is the water inlet The heat exchanger according to claim 4, wherein a portion facing the heat exchange flow path closer to the water outlet is formed thicker than a portion facing the heat exchange flow path closer to the water outlet. The flat heater is a ceramic heater comprising a ceramic substrate, a heating resistor formed by pattern printing of a resistor on the ceramic substrate, and an electrode, and a gap between lines of the printed pattern is the front. The heat exchanger according to claim 4, wherein a portion facing the heat exchange flow path on the side close to the water outlet is formed wider than a portion facing the heat exchange flow path on the side close to the entry water port. The sanitary washing apparatus provided with the heat exchanger of any one of Claims 1-6.