Patent Publication Number: US-2007108304-A1

Title: Hot water supply device

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a hot water supply device used as a hot water supply system that supplies hot water from a hot water heater to a kitchen, a bathroom, a wash hand basin, or other hot water supply faucets, and in particular relates to a heat storage device with a heating function, provided on the hot water supply pipe of the hot water supply device that uses wax or a similar heat storage medium so that hot water at a predetermined temperature can be obtained instantaneously.  
      2. Description of the Related Art  
      Conventionally, the device shown schematically in  FIG. 3  is known as this type of hot water supply device. Simply explained,  1  is a hot water heater comprising a commonly known heating source or heat exchanger or similar, and cold water is supplied to the hot water heater  1  by a pipe  3  that branches from a cold water supply pipe  2  in which tap water or similar cold water flows.  3  is a pressure regulating valve provided on the cold water supply pipe  2 .  
       4  is a hot water supply pipe in which hot water heated in the hot water heater  1  is supplied, so that hot water is supplied for example to the hot water faucet of a wash hand basin  5 . Also, the cold water supply pipe  2  is connected to the cold water faucet of the wash hand basin  5 , so that cold water can be supplied.  
      Incidentally, in this type of hot water supply device the wash hand basin  4  or similar forming the hot water supply side is frequently located separated from the hot water heater  1 . In this way, when the length of the hot water supply pipe  4  becomes long, if supply of hot water is stopped for a while the heat in the hot water remaining in the pipe is gradually dispersed and the water cools. Then when the hot water supply is turned on again it is inevitable that cold water is discharged until the water remaining in the pipe has been discharged.  
      To eliminate this kind of problem in a conventional hot water supply device a simple electrical water heater  6  is provided just before the hot water faucet of the wash hand basin  5  forming the hot water supply side of the hot water supply pipe  4  from the hot water heater  1 , so that the water remaining in the pipe  4  can be heated. In other words, water is stored in a hot water storage tank  7 , and the tank  7  itself heats the water using a heating unit and stores the hot water, and in this way when the hot water is opened again cold water is not discharged.  
      In the figure,  8  is a pressure regulating valve provided upstream of the hot water storage tank  7 , that suppresses the rises in pressure that occur due to thermal expansion and contraction of the hot water. Furthermore, as shown in the figure, to the rear and the front of the electrical water heater  6 , a reverse flow prevention valve with reverse flow prevention capability to prevent reverse flow and a flow rate control valve to control the flow rate of hot water into and out of the storage tank  6  are provided.  
      Also, in the conventional hot water supply device as described above, to limit sudden variations in water temperature when supplying hot water heated in a boiler or hot water heater or similar to a kitchen, hot water faucets, room heating equipment, or the like, a thermal shock absorber device has been proposed as a structure provided in the hot water supply pipe from the hot water heater to the hot water faucet or similar (see for example Japanese Utility Model Application Laid-open No. H1-42767).  
      Simply explained, the thermal shock absorber device is constituted so that a heat exchange unit is provided on the hot water supply pipe, and a jacket is provided surrounding the heat exchange unit and wax or a similar heat storage medium is enclosed within the jacket, so that the water flowing in the pipe is maintained near a predetermined temperature by the heat storage medium via the heat exchange unit. In other words, when the water temperature is too high heat is stored in the heat storage medium, and when the water temperature is too low the hot water is heated by the heat that has been stored.  
     SUMMARY OF THE INVENTION  
      However, in the hot water supply devices as described above, each had the unavoidable problem that the structure is complex, and the size tends to be large, and after the hot water supply is turned off for a while and turned on again after a certain period of time has passed, cold water will be discharged.  
      In other words, in the former conventional device, there were the problems that the overall device tended to be large because of the necessity to provide the electric water heater  6  with the hot water storage tank  7  and the pressure regulating valve  8 , and moreover there were restrictions on the location to install the electric water heater  6 , so there was no freedom of installation, and so on.  
      On the other hand, in the latter conventional device there were the problems that in the thermal shock absorber device used to maintain the predetermined water temperature, the heat storage medium that exchanges heat with the hot water via the heat exchange unit is formed from a material such as wax whose volume varies with thermal expansion and contraction, so it was necessary to form the jacket from a material that expands and contracts such as rubber, or provide a bellows in the part that encloses the space for the heat storage medium, so the structure became complex, and the size tended to be large.  
      In particular, in a structure in which the jacket made from a material that expands and contracts in this way is the casing, the casing has no strength, so it was necessary to install the casing in a location that would not affect the expansion and contraction, so there were limitations on the installation locations, and so on.  
      Furthermore, in the conventional device described above, when the required amount of heat is stored in the heat storage medium it is possible to heat water, but when there is no heat or insufficient heat stored, there was the problem that it was not possible to obtain hot water at the predetermined temperature.  
      With the foregoing in mind, it is an object of the present invention to obtain a hot water supply device in which the overall system is small and compact, and for which there is freedom of installation of each part, and moreover by using wax or a similar heat storage medium, hot water at a predetermined temperature can be instantly obtained, and hot water is supplied to the hot water supply side.  
      To achieve these objects the hot water supply device according to the present invention (the invention according to claim  1 ) is a hot water supply device comprising a heat storage device with a heating function which is provided on a hot water supply pipe and which indirectly heats water in the pipe using a heat storage medium to obtain hot water, the heat storage device with a heating function comprising: a piping portion connected to the hot water supply pipe; a heat storage medium that exchanges heat with the piping portion; and a casing disposed so as to enclose the heat storage medium and surround the piping portion, the piping portion comprising an elastically deformable bellows-shaped portion that exchanges heat with the heat storage medium, and the casing comprising heating means capable of heating the heat storage medium in accordance with temperature conditions thereof.  
      The hot water supply device according to the present invention (the invention according to claim  2 ) is the hot water supply device according to claim  1 , further comprising: a temperature sensor that measures temperature of the heat storage medium; and a temperature controller that controls heating by the heating means in accordance with temperature information from the temperature sensor, wherein the temperature controller controls the temperature of the heat storage medium to a predetermined set temperature.  
      The hot water supply device according to the present invention (the invention according to claim  3 ) is the hot water supply device according to claim  2 , wherein a melting point of the heat storage medium is equal to or less than the set temperature.  
      As explained above, the hot water supply device according to the present invention has the superior effect that, unlike the conventional electrical water heater, instantaneous heating is possible, so the hot water storage tank is not required, the pressure regulating valve is unnecessary, and the flow rate control valve that controls the quantity of hot water stored is unnecessary, so it is possible to make the overall size small and compact, there are no restrictions on the installation location or similar, the structure is simple, and furthermore it is possible to appropriately supply the required hot water as a hot water supply device.  
      In particular, in the present invention, according to the heat storage device with a heating function, the piping portion is formed in a bellows shape, so changes in volume due to expansion and contraction of the heat storage medium can be absorbed, and also the surface area of the pipe is increased due to the bellows shape, which is advantageous from the point of view of the heat exchange efficiency.  
      Furthermore, not only is the heat storage device with heating function according to the present invention compact and has superior heat exchange efficiency, but also by measuring the temperature of the heat storage medium, the heating by the heating means is controlled to the required state, so it is possible to control the temperature of the supplied hot water to the required state, which has the advantage that when the hot water supply is opened again hot water can be instantaneously obtained. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows an embodiment of the hot water supply device according to the present invention, a cross-section view of the principal parts showing the characteristic heat storage device with a heating function;  
       FIG. 2  is a schematic diagram of the whole system showing an embodiment of the hot water supply device according to the present invention; and  
       FIG. 3  is a schematic diagram for explaining one example of conventional hot water supply device.  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       FIG. 1  and  FIG. 2  show one embodiment of the hot water supply device according to the present invention, and in these figures parts that are the same or equivalent to those in  FIG. 3  and which have been described already are given the same reference numerals and their detailed explanation has been omitted.  
      According to the present invention, instead of the electrical water heater  6  comprising the hot water storage tank  7  as described above in  FIG. 3 , a heat storage device  10  with a heating function is provided, as shown in  FIG. 2 .  
      Explaining the heat storage device  10  with a heating function in detail using  FIG. 1 , the heat storage device  10  with a heating function is installed on the hot water supply side of the hot water supply pipe  4  that supplies hot water from the hot water heater  1  to the hot water faucet of the wash hand basin  4  forming the hot water supply side.  
      The heat storage device  10  with a heating function comprises a piping portion  11  formed from part of the hot water supply pipe  4 , a casing  12  comprising a cylindrical shaped case  12   a  having a cylindrical shape with a bottom arranged so as to surround the piping portion  11  and a lid  12   b  that closes one end of the case  12   a , a heat storage medium  13  such as wax or similar enclosed in the space formed within the casing  12 , and heating means  14  comprising a film heater or similar provided in the peripheral wall portion of the space within the casing  12 .  
      Here, the piping portion  11  referred to above is formed into a bellows-shaped portion  11   a  in the part that is in contact with the heat storage medium  13 , so that the volumetric changes of the heat storage medium  13  due to thermal expansion and thermal contraction can be followed by the expansion and contraction of the bellows-shaped portion  11   a . At the penetration portions where the piping portion  11  penetrates the casing  12 , O-rings  15   a ,  15   b  are provided to prevent liquid leakage of the heat storage medium  13 , formed so that there is no obstacle to the stroke movements of the piping portion  11  in the pipe direction that accompany the volumetric changes referred to above. A structure to allow this type of stroke movements may be provided on both ends of the piping portion  11 , or on one side only.  
      Also,  16  in the figure is a temperature sensor that measures the temperature of the heat storage medium  13 , and  17  is a temperature control unit, that receives temperature information and the like from the temperature sensor and controls heating by the heating means  14 , constituted so that the heat storage medium  13  can be heated using the heating means  14 . A thermo-switch that turns ON or OFF at a fixed temperature may be used as the temperature sensor  16 . In other words, the temperature sensor  16  is a device suitable for determining whether the temperature of the heat storage medium  13  is greater than or less than a predetermined temperature, and for controlling whether to the heat storage medium  13  with the heating means  14 .  
      Here, as stated above, when using the heat storage medium  13  maintenance of temperature is superior and heat does not dissipate easily compared with the case where water or the pipe is directly heated, which has the advantage that heat once applied is not wasted and energy losses are small. Therefore, the amount of heating by the heating means  14  may be small, and can be controlled by a comparatively small heating means  14  and temperature control unit  17 , so the present invention is superior from the practical point of view.  
      Furthermore, a flow rate control valve  18  may be provided on the hot water supply side of the piping portion  11  to control the flow rate of the hot water according to the temperature, constituted so that appropriate temperature control can be carried out, but for example the hot water faucet in the wash hand basin  5  in  FIG. 2  may be used as this type of flow rate control valve  18 .  
      Also, on the hot water heater  1  side of the piping portion  11 , a reverse flow prevention valve  19  may be provided to prevent reverse flow to the water supply side.  
      According to the heat storage device  10  with a heating function as described above, the heat storage medium  13 , whose temperature fluctuates due to the heat exchange with the hot water, can be heated in advance by the heating means  14  in accordance with the temperature conditions. In other words, when the temperature of the hot water is low and the temperature of the heat storage medium  13  is low, heating can be carried out by the heating means  14  until a predetermined temperature is reached.  
      At this time, by setting the melting point (the temperature at which it changes from solid to liquid) of the heat storage medium  13  to be equal to or less than the set temperature, the heat storage efficiency can be further improved. For example, if the heat storage temperature is controlled by the temperature sensor  16  and the temperature control unit  17  to be 90° C., the melting point of the heat storage medium  13  may be set near 70° C.  
      According to this kind of configuration, the heated heat storage medium  13  is a heat source, and hot water that has exchanged heat via the bellows-shaped portion  11   a  which is the heat exchange unit of the piping portion  11  can be heated to a predetermined temperature and supplied to the hot water supply side.  
      The volumetric increase due to the thermal expansion due to heating of the heat storage medium  13  is absorbed by expansion and contraction of the elastically deformable bellows-shaped portion  11   a  of the piping portion  11 .  
      Also, according to a hot water supply device using this type of heat storage device  10  with a heating function, unlike the conventionally used electrical water heater, instantaneous heating is possible, so the hot water storage tank is not necessary, and therefore the pressure regulation valve is also unnecessary. Therefore, compared with a conventional device the overall form is more compact, the size of the device can be greatly reduced, and there are also structural advantages.  
      Also, according to a hot water supply device using this type of heat storage device  10  with a heating function, the heat exchange unit of the piping portion  11  is a bellows-shaped shaped portion  11   a , so thermal expansions and so on of the heat storage medium  13  can be absorbed, also the surface area of the pipe is increased by the bellows-shaped portion  11   a , which has the advantage that the heat exchange efficiency can be increased.  
      Therefore, according to a hot water supply device using this type of heat storage device  10  with a heating function, although the form is small and compact, cold water can be instantaneously heated to create hot water in a short period of time, so the hot water storage tank, in which hot water that is once heated is stored as in the conventional devices, can be eliminated.  
      Also, the volumetric changes of the hot water can be absorbed by the bellows-shaped portion  11   a  as stated above, so a pressure control valve (pressure regulating valve or the like) to reduce the pressure rise due to volumetric expansion in the hot water supply pipe  4  as in the conventional device is unnecessary, which results in the advantage that the hot water supply device as a whole is smaller and simpler.  
      Furthermore, in the hot water supply device using this type of heat storage device  10  with a heating function as described above, the function of absorbing the volumetric changes of the heat storage medium  13  is provided by the piping portion  11 , so unlike the conventional device the casing  12  can be made from a rigid material, which has the advantage that the freedom of the installation location of the device  10  is increased.  
      Also, the hot water supply device using this type of heat storage device  10  with a heating function as described above can be made in an extremely compact form, so there are no restrictions on installation location, and the device can be installed directly before the hot water supply side. For example, in a hot water device for a wash hand basin  5 , the pipe from the hot water heater  1  to the hot water supply faucet is long, so if hot water is not used for a while the hot water that was once heated becomes cold water, and when hot water is required again for a while cold water is discharged, which had the problem that it was a discomfort for the user, however, this can be solved by providing the hot water supply device using this type of heat storage device  10  with a heating function that is a characteristic of the present invention directly before the hot water supply side. This is because by doing so it is clear that hot water can be instantaneously supplied.  
      Furthermore, according to the hot water supply device using this type of heat storage device  10  with a heating function, despite the fact that the device is compact with a superior heat exchange efficiency, heating by the heating means  14  is controlled by measuring the temperature and the like of the heat storage medium  13 , which has the advantage that the temperature of the supplied hot water can be controlled to be in the required state. Also, the electrical power consumption of the heating means  14  can be maintained at the lowest necessary level.  
      The present invention is not limited to the structure explained in the embodiment described above, and it is unnecessary to say that the shape, structure, and so on of each part forming the hot water supply device may be changed and altered as appropriate.  
      For example, in the embodiment described above, a wash hand basin  5  was shown as an example, but the present invention is not limited to this, and it is obvious that the present invention may be applied to the supply of hot water to a domestic water heater, bathtub or kitchen hot water supply faucet, or to the supply of hot water to a supplementary heating device for a bathtub, or similar.  
      Also, in the embodiment described above, the heat storage device  10  with a heating function that is a characteristic of the present invention was explained for the case where the device is provided close to the hot water supply faucet of the wash hand basin  5  which is the hot water supply side, but the present invention is not limited to this, and the device may be incorporated within the hot water heater  1  for example.