JP3906381B2 - Dishwasher heat exchanger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat exchange device that raises the temperature of a fluid such as water or a refrigerant by using heat of alkaline hot water such as hot water from a dishwasher.
[0002]
[Prior art]
For example, in the field of dishwashers, the temperature of newly supplied rinse water is raised using the heat of the hot water after completion of rinsing from the viewpoint of saving energy and reducing running costs. ing. Specifically, a feed pipe that feeds the raw water of the rinse water is provided in a tank that collects the hot water from the dishwasher, and heat is exchanged with the hot water while the raw water is fed to the feed pipe. The temperature of the raw water is raised.
In general, a copper tube excellent in thermal conductivity is suitable as a feed tube for heat exchange. On the other hand, the dishwasher uses an alkaline detergent so that oils and fats can be removed satisfactorily. Therefore, the hot water from the dishwasher is strongly alkaline and has a pH of about 11. The above copper tube tends to corrode somewhat in an aqueous solution of strong alkali, and since the hot water is supplied at a relatively high temperature of 50 to 60 ° C., it can be said that the corrosion reaction is likely to occur. A copper tube alone has a problem in corrosion resistance.
Therefore, conventionally, when exchanging heat with the hot water of this type of dishwasher, a feed pipe in which the outer surface of the copper pipe is subjected to nickel plating resistant to alkali has been used.
[0003]
[Problems to be solved by the invention]
However, it is unlikely that plating can be done perfectly, and pinholes are created. When there was a pinhole in this way, there was a concern that the copper pipe would corrode early from that portion and a hole would be opened in the feed pipe. In other words, the conventional ones are not always satisfactory in terms of durability.
The present invention has been completed based on the above circumstances, and its purpose is to improve its corrosion resistance and improve durability with respect to a feeding tube used by being immersed in alkaline hot water. It is an object of the present invention to provide a heat exchange device.
[0004]
[Means for Solving the Problems]
As a means for achieving the above object, the invention of claim 1 is characterized in that after washing the dishes with the washing water in the washing tank, the washing water is collected in the washing tank and then stored in the hot water storage tank. A rinsing cycle is performed in which the hot water is rinsed and the hot water is collected in the washing tank. Alkaline waste water overflowing from the washing tank in accordance with the rinsing cycle is collected in the hot water collecting tank. The dishwasher is equipped with a heat pump that configures a refrigeration cycle by connecting a compressor, a condenser, an expansion valve, and an evaporator, and the evaporator in this heat pump can exchange heat in the waste water recovery tank. the provided Rutotomoni, the condenser water supply pipe and the heat exchangeably provided in the raw water, also in the hot water storage tank, stored Water is turned off below the predetermined amount, the float switch for turning on at the return of the predetermined amount is provided by the supply, the float switch to enter the rinse cycle that the compressor of the heat pump where turned off is operated The hot water is generated by raising the temperature of the raw water while recovering heat from the waste water and supplied to the hot water storage tank, and the compressor is stopped when the hot water is replenished and the float switch is turned on. And the evaporator is formed by tinning the outer surface of a copper tube , and the waste water recovery tank is provided with a normally open drain valve mechanism, and the float switch is turned off. the drain valve is closed, have control means for valve opening control of the drain valve is provided where Thereafter the float switch is turned on when a Characterized in was and configuration.
[0005]
[Action and effect of the invention]
<Invention of Claim 1>
According to the evaporator of the present invention, the following effects are exhibited. Compared with copper, tin that is weak against alkali is plated, so that tin functions as a sacrificial anode for copper and elutes in the hot water preferentially over copper, so that even if some tin plating occurs While remaining on the outer surface of the tube, corrosion of the copper tube does not begin. Even if there is a pinhole in the tin plating, there is no adverse effect on the corrosion of the copper tube. Thereby, the corrosion resistance of the evaporator can be substantially increased, and the product life of the heat exchange device can be extended significantly.
Moreover, since the hot water is discharged immediately after the operation of the heat pump is completed, the time during which the evaporator is immersed in the hot water, that is, the time for the corrosion reaction, can be greatly shortened, and the product life is further extended. It becomes possible.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. Here, it is a case where hot water for rinsing used in a dishwasher is generated by a hot water generator equipped with a heat pump, and the refrigerant circulating in the evaporator part of the refrigeration cycle constituting the heat pump, and the dishwasher The example which applied this invention to the part which heat-exchanges with the hot water of this is shown.
In FIG. 1, the code | symbol 1 is a tableware washing machine, Comprising: The hot water production | generation apparatus 20 equipped with the heat pump 21 is installed in the side. First, the structure of the dishwasher 1 will be described. A cleaning chamber 2 in which tableware can be put in and out through a rack (not shown) is formed on the upper side of the interior thereof. A pair of cleaning nozzles 3 and rinse nozzles 4 are disposed on the lower surface side. A cleaning tank 6 for storing cleaning water mixed with an alkaline detergent is formed on one side of the bottom surface of the cleaning chamber 2, and the cleaning water stored therein is pumped up by a cleaning pump 7 and described above. Is sprayed toward the tableware and is then circulated and supplied so as to be collected in the washing tank 6.
[0007]
A hot water storage tank 8 for storing hot water for rinsing is provided below the cleaning tank 6. In the hot water storage tank 8, as will be described in detail later, hot water generated by the hot water generator 20 is supplied and stored by a water supply pipe 10 provided with a hot water supply valve 9. The stored hot water is pumped up by the rinse pump 11, sprayed from the rinse nozzle 4 toward the tableware, and collected in the washing tank 6. The wash tank 6 is equipped with an overflow pipe 13, which takes in the hot water that has overflowed from the wash tank 6, and passes through the hot water pipe 14 to provide a hot water recovery tank 30 provided in the hot water generator 20. It is designed to be discharged inside. The washing tank 6 and the hot water storage tank 8 are equipped with heaters 15 and 16 and a thermostat (not shown), respectively, so that the washing water is kept at about 60 ° C. and the rinsing hot water is kept at about 80 ° C. ing.
That is, when the tableware is stored in the washing chamber 2, washing water is jetted from the washing nozzle 3 to wash the tableware, and then hot water is jetted from the rinse nozzle 4 to perform rinsing. Then, the hot water that has overflowed without being collected in the washing tank 6 is discharged to the hot water generator 20 to recover the exhaust heat, and the recovered heat is used as raw water such as tap water supplied to the water supply pipe 10. The hot water is generated by heat exchange with the hot water storage tank 8 and is supplied to the hot water storage tank 8 described above.
[0008]
Next, the hot water generator 20 will be described. The hot water generator 20 includes a heat pump 21 and is housed in a box-shaped casing 22. As shown in FIG. 6, in the heat pump 21, a compressor 24, a condenser 25, an expansion valve 26, and an evaporator 27 are connected in a circulating manner, and chlorofluorocarbon (R-22), which is a refrigerant, is enclosed therein so that it can circulate. This constitutes the refrigeration cycle.
The compressor 24 is comparatively large, and is installed on the bottom surface in the casing 22 as shown in FIGS. On the side of the compressor 24, a hot water recovery tank 30 for storing hot water from the dishwasher 1 is installed.
[0009]
As shown in FIGS. 4 and 5, the hot water recovery tank 30 has a cross-sectional shape formed in a shape in which a half area of a square is a semicircular shape. A cover plate 31 having a bent portion 31a is attached to the surface. An evaporator 27 that is a component part of the refrigeration cycle is housed in the waste water recovery tank 30. The evaporator 27 is formed by applying a tin plating 63 to the outer peripheral surface of the copper tube 62. The evaporator 27 is formed and stored in a coil shape along the inner peripheral surface of the semicircular portion of the hot water recovery tank 30, and its inlet 27a and outlet 27b are formed in square corner portions. It protrudes to the upper surface of the cover plate 31 through the excess space, and is connected to the refrigerant pipe 21a.
A hot water inlet 32 is provided on one side of the upper part of the hot water recovery tank 30 and is connected to a hot water pipe 14 drawn from the overflow pipe 13 of the cleaning tank 6 in the dishwasher 1. The hot water overflowed from 6 can be introduced. On the other side, a discharge port 33 for discharging the overflow water of the hot water recovery tank 30 itself is provided, and a drain pipe 34 is connected.
[0010]
The lid plate 31 is provided with a shaft 38 provided with a propeller-like stirring tool 36 at the tip, and the stirring tool 36 is positioned at a substantially central height inside the coil of the evaporator 27. The stirrer 36 is rotationally driven through a shaft 38 by a drive motor 37 provided on the lid plate 31.
A normally-open drain valve 40 is provided on the bottom surface of the hot water recovery tank 30. More specifically, a valve body 43 that opens and closes to the upper surface side of the valve port 42 that is opened on the bottom surface is provided at the tip of the rod 41 that passes through the cover plate 31 and that is freely movable up and down. Is provided with a spring member 44 that constantly urges the valve to move upward. A solenoid 46 is attached to the cover plate 31 downward via a bracket 45. Then, the rod 41 is always urged upward by the elastic force of the spring member 44, hits the plunger 46a of the solenoid 46, and the valve body 43 is pulled up as shown by the chain line in FIG. When the solenoid 46 is excited and the solenoid 46 is energized, the plunger 46a advances and pushes down the rod 41 and the valve body 43 against the urging force to close the valve port 42 as shown by the solid line in FIG. It is like that. The drain valve 40 joins and is connected to the drain pipe 34 described above.
Further, the cover plate 31 of the hot water recovery tank 30 is provided with two watering nozzles 48 for cleaning the water by spraying hot water toward the evaporator 27.
[0011]
The condenser 25 is formed in the shape of a large-diameter pipe, and a middle portion of the water supply pipe 10 that feeds the raw water of the rinse water is inserted into the condenser 25 to form a double pipe portion 28 that enables heat exchange. Has been. As shown in FIGS. 2 and 3, the double pipe portion 28 is stretched around the inside of the two side surfaces of the casing 22 while being bent. The outlet side of the water supply pipe 10 is connected to the hot water storage tank 8 of the dishwasher 1 as described above. The expansion valve 26 is a temperature type provided with a temperature sensitive cylinder 26a (see FIG. 6). In addition, a control box 49 that houses a device for controlling the refrigeration cycle, water supply / drainage, and the like of the heat pump 21 is provided in the casing 22.
[0012]
Further reference is made to the refrigeration cycle with reference to FIG. A bypass pipe 51 is provided between the high pressure side and the low pressure side of the compressor 24, and a capacity adjustment valve 52 is provided there. This capacity adjustment valve 52 bypasses the high-pressure side hot gas to the low-pressure side when the heat load (heat source) is insufficient or at the time of initial hot water supply, and the pressure on the low-pressure side decreases excessively. It works to prevent you from doing.
An automatic water supply valve 53 is provided at the place where the double water pipe portion 28 in the water supply pipe 10 exits. The automatic water supply valve 53 functions to detect the pressure on the high-pressure side, adjust the amount of water supply accordingly, and keep the pressure on the high-pressure side constant. Along with this, hot water having a substantially constant temperature can be taken out.
On the upstream side of the automatic water supply valve 53 in the water supply pipe 10, a watering hose 55 provided with a diversion valve 54 is branched and connected. This watering hose 55 is provided on the lid plate 31 of the above-described hot water recovery tank 30. Connected to the watering nozzle 48. The diversion valve 54 is opened when the operation is stopped, thereby discharging the hot water remaining in the double pipe portion 28 and using it for cleaning the evaporator 27, as well as a transient condensing capacity at the start of the operation. It works to prevent shortages.
[0013]
The refrigerant pipe 21a on the outlet side of the condenser 25 and the portion on the near side that enters the double pipe portion 28 in the feed pipe 10 of the raw water are closely connected in parallel, whereby the first auxiliary heat exchanging portion 57 is It is configured. The first auxiliary heat exchanger 57 functions to preheat the raw water by exchanging heat between the liquid refrigerant discharged from the condenser 25 and the raw water of the rinse water.
Further, the refrigerant pipe 21a on the downstream side of the portion constituting the first auxiliary heat exchanging portion 57 and the refrigerant pipe 21a on the outlet side of the evaporator 27 are similarly piped in parallel to form the second An auxiliary heat exchanging unit 58 is configured. The second auxiliary heat exchanging unit 58 heats the low-temperature refrigerant that has passed through the evaporator 27 with the high-temperature liquid refrigerant that has come out of the condenser 25, so that the liquid return phenomenon to the compressor 24 side occurs particularly in the latter half of the operation. It functions to suppress and increase heat utilization efficiency.
[0014]
A receiver 59 is interposed in the refrigerant pipe 21 a between the portion constituting the second auxiliary heat exchange unit 58 and the expansion valve 26. The receiver 59 functions to prevent liquid refrigerant from staying in the condenser 25, for example, when the refrigerant is overfilled or when the internal balance is lost and the liquid refrigerant becomes excessive. .
A refrigerant solenoid valve 60 is interposed between the receiver 59 and the expansion valve 26. The refrigerant solenoid valve 60 functions to maintain a high pressure by preventing high pressure gas from leaking from the expansion valve 26 to the low pressure side when operation is stopped.
[0015]
The present embodiment has the structure as described above, and the operation thereof will be described with reference to the timing chart of FIG. The washing operation is performed when the washing tank 6 and the hot water storage tank 8 of the dishwasher 1 are full.
The tableware to be cleaned first is stored in the rack and accommodated in the cleaning chamber 2 (rack operation). When the rack operation is completed, a cleaning cycle is started, and a cleaning operation in which cleaning water in the cleaning tank 6 is pumped up by the cleaning pump 7 and ejected from the cleaning nozzle 3 is performed for several tens of seconds. After a stop time (water draining time) of about 5 seconds, a rinsing cycle is subsequently started, and a rinsing operation in which hot water in the hot water storage tank 8 is pumped up by the rinsing pump 11 and ejected from the rinsing nozzle 4 is 7 seconds. Done about. After that, a stop time of about 5 seconds (similarly draining time) is set, whereby one cleaning process is completed.
[0016]
In the above, when the rinsing cycle is started, the float switch provided in the hot water storage tank 8 is turned off, so that the hot water supply valve 9 is opened, the compressor 24 is turned on, and the heat pump 21 starts operating. . At the same time, the refrigerant solenoid valve 60 is also opened. Further, the solenoid 46 provided in the hot water recovery tank 30 is excited to close the normally open drain valve 40, and the stirrer 36 is driven to rotate. The hot water overflowing from the washing tank 6 after the start of the rinsing cycle flows into the hot water recovery tank 30 with a slight delay, and the evaporator 27 actually starts to absorb heat after a few seconds.
[0017]
Now, in the hot water recovery tank 30, the hot water overflowed from the cleaning tank 6 of the dishwasher 1 is taken in little by little (over several tens of seconds). The heat pump 21 is fully operated from the middle of taking in the hot water and supplies the liquid refrigerant to the evaporator 27. The hot water is stirred by the stirrer 36 to start heat absorption while heat exchange is promoted. Since the time during which heat can actually be absorbed is several tens of seconds, the expansion valve 26 having a relatively large flow rate (refrigeration capacity) is used, and a large amount of refrigerant is supplied immediately after the rise.
During the endothermic process, the overflow from the cleaning tank 6 ends first, and the hot water recovery tank 30 becomes full. Although the heat absorption continues further, when the refrigerant reaches the evaporator 27 sufficiently, the temperature detected by the temperature sensing cylinder 26a decreases, and the expansion valve 26 begins to close. However, since the timing of the flow rate control of the expansion valve 26 is inevitably delayed, the liquid returns slightly. Therefore, the liquid return is suppressed by being heated by the second auxiliary heat exchanging unit 58, and the heat utilization efficiency is improved at the same time.
[0018]
During the endothermic operation, the evaporator 27 is immersed in the alkaline hot water, but the evaporator 27 has a structure in which the outer surface of the copper tube 62 is tin-plated 63. It functions as a sacrificial anode for copper and elutes in the hot water preferentially over copper, and corrosion of the copper tube 62 does not start while some tin plating 63 remains on the outer surface of the copper tube 62. . Of course, even if there is a pinhole in the tin plating 63, there is no adverse effect on the corrosion of the copper tube 62. Moreover, since the temperature of the hot water is reduced to about 15 ° C. by heat recovery, corrosion is less likely to proceed.
[0019]
During this time, the raw water of the rinsing water fed to the water supply pipe 10 is preheated by the first auxiliary heat exchanging section 57, and then heat-exchanged with the refrigerant in the double pipe section 28 so as to be heated to become hot water. It is gradually supplied to the hot water storage tank 8 of the dishwasher 1 through the valve 9. When a predetermined amount of hot water is accumulated in the hot water storage tank 8 and the float switch is turned on, the compressor 24 is turned off, the refrigerant solenoid valve 60 is closed, and the operation of the heat pump 21 is stopped.
Further, the drain valve 40 of the hot water recovery tank 30 is opened, and the stirring tool 36 is stopped. As a result, the hot water in the hot water recovery tank 30 is discharged. However, since the hot water is discharged as an eddy current due to the inertial force, for example, it is assumed that foreign substances such as food strips are mixed in the hot water. In addition, all of the water is discharged together with the vortex and there is no possibility that the tank 30 is dirty. As the float switch is turned on, the diversion valve 54 is opened for 10 to 15 seconds, and the hot water remaining in the double pipe portion 28 is diverted to the watering hose 55 side. The hot water is sprinkled from the water spray nozzle 48 of the hot water recovery tank 30 toward the evaporator 27, and the surface of the evaporator 27 is washed. After that, the hot water in the hot water recovery tank 30 is completely discharged, and the dishwasher 1 can be rinsed.
Further, when the heat recovery is completed as described above, the hot water in the hot water recovery tank 30 is immediately discharged, so that the time during which the evaporator 27 is immersed in the hot water, that is, the time for the corrosion reaction, is kept small. In addition, corrosion of the tin plating 63 itself is also suppressed.
As described above, the cleaning operation and the generation of warm water with heat recovery are repeated.
[0020]
As described above, according to the present embodiment, the evaporator 27 immersed for heat exchange in the alkaline hot water from the dishwasher 1 has tin which is weaker to alkali than the copper on the outer surface of the copper tube 62. Since it is formed by plating 63, tin functions as a sacrificial anode with respect to copper and preferentially elutes into the hot water while being immersed in the hot water, and the tin plating 63 remains. As long as the copper tube 62 is corroded, it is prevented. Further, since the hot water is discharged immediately after the heat exchange is completed, the time during which the evaporator 27 is immersed in the hot water, that is, the time for the corrosion reaction is greatly shortened, and the corrosion of the tin plating 63 itself is also suppressed. The Thereby, the corrosion resistance of the evaporator 27 is substantially enhanced, and the product life can be greatly extended.
Further, since the tin plating itself is inexpensive, has good compatibility with copper and is easy to manufacture, the evaporator 27 itself can be manufactured at a low cost.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the overall structure of an embodiment of the present invention.
FIG. 2 is a cross-sectional view seen from the upper surface of the hot water generator.
FIG. 3 is a cross-sectional view seen from the front.
FIG. 4 is a cross-sectional view seen from the upper surface of the hot water recovery tank.
FIG. 5 is a cross-sectional view seen from the front.
FIG. 6 is a refrigeration cycle diagram of a heat pump.
FIG. 7 is a timing chart during a cleaning operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Dishwasher 21 ... Heat pump 27 ... Evaporator 30 ... Waste water recovery tank 40 ... Drain valve 62 ... Copper pipe 63 ... Tin plating

Claims (1)

After washing the dishes with washing water in the washing tank and then collecting the washing water in the washing tank, rinsing with warm water stored in the hot water storage tank and collecting the same warm water in the washing tank In the dishwasher in which alkaline waste water overflowed from the washing tank as a result of execution of this rinsing cycle can be collected in the waste water collection tank,
Compressor, condenser, expansion valve and evaporator heat pump constitutes a refrigeration cycle by connecting pipes are provided, the evaporator in the heat pump is provided so that heat can be exchanged into the Haiyu recovery tank Rutotomoni, The condenser is provided so as to be able to exchange heat with a raw water supply pipe,
The hot water storage tank is provided with a float switch that turns off when the stored hot water falls below a predetermined amount, and turns on when the predetermined amount is restored by replenishment.
When the rinsing cycle is entered and the float switch is turned off, the compressor of the heat pump is operated to generate hot water by raising the temperature of the raw water while recovering heat from the waste hot water, to the hot water storage tank. Supplied, warm water is replenished and the compressor is stopped when the float switch is turned on,
The evaporator is formed by tinning the outer surface of a copper tube, and the drainage recovery tank is provided with a normally open drain valve mechanism, and when the float switch is turned off. A heat exchanging apparatus for a dishwasher, wherein the drain valve is closed, and thereafter, when the float switch is turned on, control means is provided for controlling the opening of the drain valve .

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