Water heater and control method

Abstract

The present invention relates to the field of water heaters, and in particular to a water heater and a control method. The water heater of the present invention comprises a housing, an inner tank, an instant heating unit, a heat storage and heating unit, a water flow switch, a control unit, a temperature sensor, a water inlet end and a water outlet end, and further comprises a heat exchanger and a pump, wherein the water inlet end, the heat exchanger, the instant heating unit and the water outlet end are sequentially connected to form an instant heating channel; the heat exchanger, the pump and the inner tank are connected to form a circulating heat exchange channel; the heat storage and heating unit is used for heating a heat storage medium in the inner tank; and the control unit controls working states of the instant heating unit, the heat storage and heating unit and the pump on the basis of one or more of a working mode, a water flow state and temperature of the water heater. The control method comprises: acquiring one or more of working mode, temperature and water flow state information of a water heater; on the basis of the acquired parameters, determining whether a pump needs to be started or not; if yes, controlling water outlet temperature by controlling the flow rate of pump; and if not, controlling the water outlet temperature by controlling the power of an instant heating unit.

Description

Water heater and control method Technical Field

[0001] The invention belongs to the field of water heaters, in particular to an electric water heater. Background Art

[0002] Electric storage water heaters consume a lot of energy, making them insufficient for multiple bathing groups. They are bulky and unsightly, and scale accumulation affects water hygiene. The pressure on the inner tank can cause the tank to burst. The alternating high pressure and temperature can cause microcracks and corrosion in the enamel, leading to stress corrosion in the stainless tank. Instant water heaters require a lot of power, making them unsuitable for most households. Even with high power, the water flow is very low in winter, and multiple simultaneous water supply lines are impossible, resulting in a poor user experience. Dual-mode, fast-heating water heaters attempt to solve the problem by combining the advantages of both. However, due to the small size of the inner tank and the rapid drop in water temperature, a thermostatic valve is required for an acceptable bathing experience. Due to the effects of scale, sediment, high temperature, and high pressure, the thermostatic valve has a high failure rate, exceeding market acceptance. Furthermore, the inner tank of an instant water heater has a small capacity, and scale accumulation has a significant impact. In areas with severe scale, the tank can be half full within just two to three years. The inner tank of an instant water heater also suffers from the same problems as storage water heaters. In order to solve the problems of scale and inner tank corrosion in instant water heaters, heat exchange water heaters have appeared on the market. However, the existing heat exchange solutions have brought greater problems than traditional water heaters. Although the problem of scale formation in the inner tank and heater has been solved, scale will form in the heat exchange tubes, which will lead to poor heat exchange or even blockage, making it unusable. This is more fatal than the impact of storage type scale. At the same time, there is a heat exchange temperature difference in heat exchange water heaters and the efficiency is low. Since the heat exchanger is placed in the inner tank, there will be a stream of very hot water when the water is turned off and then turned on, and there is even a risk of scalding. Therefore, this type of water heater must also have a thermostatic valve to have a suitable experience. As mentioned above, the failure rate of the thermostatic valve is high.

[0003] The water heater of this application has developed a new heat exchange solution and constant temperature technology based on a comprehensive and in-depth understanding of electric water heater products and the market, which solves the problems existing in the above-mentioned water heaters and has very practical significance. Technical issues

[0004] In order to solve the deficiencies of existing water heater technology, the present invention provides a new technical solution. Technical Solutions

[0005] The purpose of the present invention is to be solved by the following technical solutions:

[0006] A water heater comprises an outer shell, an inner tank, an instant heating unit, a thermal storage heating unit, a water flow switch, a control unit, a temperature sensor, a water inlet, a water outlet, and also comprises a heat exchanger and a pump. The water inlet, heat exchanger, instant heating unit, and water outlet are connected in sequence to form an instant heating channel; the heat exchanger, pump, and inner tank are connected to form a circulating heat exchange channel; the thermal storage heating unit is used to heat the thermal storage medium in the inner tank; the control unit controls the operating state of the instant heating unit, the thermal storage heating unit, and the pump according to one or more of the water heater operating mode, water flow state, and temperature.

[0007] Optionally, the inner tank is connected to the atmosphere and also includes a liquid level sensing unit and a water supply valve. The liquid level sensing unit is arranged on the inner tank or a component connected to the inner tank and is used to sense the liquid level of the inner tank; the inner tank is connected to the instant heating channel through the water supply valve.

[0008] Furthermore, the water supply valve is connected to the inner tank through the heat exchanger, and is used to remove air in the heat exchanger and the pump when filling water.

[0009] Furthermore, it also includes a liquid level tube, the liquid level sensing unit is installed in the liquid level tube, and the liquid level tube is connected to the inner tank.

[0010] Optionally, it further includes a heat conducting sheet and a temperature control switch, wherein both ends of the heat conducting sheet are thermally coupled with the instant heating unit and the heat storage heating unit or the inner tank respectively, and the temperature control switch is installed on the heat conducting sheet.

[0011] Optionally, the control unit includes a speed regulating module, and the control unit controls the speed of the pump according to the temperature parameter of the water heater to adjust the outlet water temperature.

[0012] Optionally, a flow regulating valve is further included, which is arranged on the circulating heat exchange channel. The control unit controls the opening of the flow regulating valve to control the flow of the pump, thereby controlling the water outlet temperature of the water heater.

[0013] Optionally, the pump is provided at one end of the heat exchanger where water flows out.

[0014] A control method, comprising:

[0015] Obtain one or more of the water heater's operating mode, temperature, and water flow status information;

[0016] Determine whether the pump needs to be started based on the acquired parameters;

[0017] If so, the outlet water temperature is controlled by controlling the pump flow rate;

[0018] If not, the outlet water temperature is controlled by controlling the power of the instant heating unit.

[0019] Optionally, the water heater parameters include one or more of an operating mode, a water flow switch state, a water inlet temperature, an inner tank temperature, and a water outlet temperature, and the control method thereof includes the following steps:

[0020] Step 1: Get the water heater working mode. If it is instant heating mode, go to step 2; if it is rapid heating mode, go to step 9.

[0021] Step 2: Is the water flow switch activated? If yes, proceed to step 3; if not, proceed to step 22;

[0022] Step 3. Is the heating unit activated? If yes, proceed to step 5; if not, proceed to step 4.

[0023] Step 4: The heating unit is started, and then step 5 is performed;

[0024] Step 5. Is the outlet water temperature lower than the set outlet water temperature? If yes, go to step 6; if not, go to step 7.

[0025] Step 6: Increase the power of the instant heating unit and then execute step 1;

[0026] Step 7. Is the outlet water temperature greater than the set outlet water temperature? If yes, go to step 8; if not, go to step 1;

[0027] Step 8: Reduce the power of the instant heating unit and then execute step 1;

[0028] Step 9: Is the water flow switch on? If yes, go to step 10; if not, go to step 18;

[0029] Step 10: Is the inner tank temperature greater than the inlet water temperature plus a? If yes, go to step 11; if not, go to step 3;

[0030] Step 11: Is the instant heating unit working? If yes, go to step 13; if not, go to step 12;

[0031] Step 12: The pump and the instant heating unit start working, and then go to step 13;

[0032] Step 13: Is the outlet water temperature lower than the set outlet water temperature? If yes, go to step 14; if no, go to step 15;

[0033] Step 14: Increase the pump flow rate and then execute step 1;

[0034] Step 15. Is the outlet water temperature greater than the set outlet water temperature? If yes, go to step 16; if not, go to step 1;

[0035] Step 16: Is the pump started? If yes, go to step 17; if not, go to step 8;

[0036] Step 17: Reduce the pump flow rate and then execute step 1;

[0037] Step 18: The pump and the instant heating stop working, and then go to step 19;

[0038] Step 19: Is the inner tank temperature lower than the inner tank set temperature? If yes, go to step 20; if not, go to step 21;

[0039] Step 20: The heat storage and heating unit starts working, and then executes step 1;

[0040] Step 21: The heat storage and heating unit stops working, and then executes step 1;

[0041] Step 22: The heating unit stops working and then executes step 1. Beneficial effects

[0042] The water heater and control method disclosed in the present application are more hygienic, energy-saving, convenient, beautiful and safe than traditional electric storage water heaters; have lower circuit requirements than instant water heaters, better installation adaptability, and larger water capacity; and achieve a constant temperature effect by adjusting the heat exchange flow rate. It is a new water heater temperature control method, more stable and durable than traditional thermostatic valves, and has great promotion significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] Figure 1 is a schematic diagram of the structure of a water heater.

[0045] Figure 2 is a schematic diagram of the structure of a water heater

[0046] Figure 3 is a schematic diagram of the structure of a water heater

[0047] Figure 4 is a schematic diagram of the structure of a water heater

[0048] Figure 5 is a schematic diagram of the structure of a water heater

[0049] FIG6 is a flow chart of a control method

[0050] Figure 7 is a logic diagram of a control method

[0051] In the picture:

[0052] 1. Outer shell 2. Inner tank 3. Instant heating unit 4. Thermal storage heating unit 5. Heat exchanger 501, heat exchanger shell 502, heat exchange tube 6, pump 7, control unit 8, water flow switch 9, temperature sensor 10, liquid level sensing unit 11, water supply valve 12, circulating water inlet pipe 13, circulating water outlet pipe 14, water inlet end 15, water outlet end 16, flow regulating valve 17, insulation layer 18, liquid level tube 19, exhaust hole 20, connecting pipe 21, thermal conductive sheet 22, temperature control switch. Best Mode for Carrying Out the Invention

[0053] It should be noted that, under the premise of no conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be further described below with reference to the accompanying drawings and embodiments. Example

[0054] A water heater comprises an outer shell 1, an inner tank 2, an instant heating unit 3, a thermal storage heating unit 4, a water flow switch 8, a control unit 7, a temperature sensor 9, a water inlet 14, a water outlet 15, and also comprises a heat exchanger 5 and a pump 6. The water inlet, heat exchanger, instant heating unit, and water outlet are connected in sequence to form an instant heating channel; the heat exchanger, pump, and inner tank are connected to form a circulating heat exchange channel; the thermal storage heating unit is used to heat the thermal storage medium in the inner tank; the control unit controls the working state of the instant heating unit, the thermal storage heating unit, and the pump according to one or more of the water heater working mode, water flow state, and temperature.

[0055] As shown in Figure 1, tap water enters the water heater at the water inlet 14, flows sequentially through the water flow switch 8, the heat exchanger 5, and the instant heating unit 3, and after being heated by the instant heating unit, flows out of the water outlet 15. This path is the instant heating channel. Compared with ordinary instant water heaters, this part only has an additional heat exchanger at the front end of the instant heating unit. Driven by pump 6, the heat storage medium in the inner tank 2 enters through the circulating water inlet pipe 12, flows through the heat exchanger 5, transfers heat to the tap water in the instant heating channel, and then returns to the inner tank 2 through the pump 6 and the circulating water outlet pipe. This heat exchange cycle is equivalent to preheating cold water. Because the temperature of the heat storage medium drops and its density decreases after heat exchange, it sinks to the bottom after entering the inner tank through the circulating water outlet pipe 13, pushing the hot heat storage medium to the top. In this way, the temperature of the heat storage medium flowing into the circulating water inlet pipe will remain relatively stable for a certain period of time. This external circulation heat exchange is much better than the structure of installing the heat exchanger in the inner tank for direct heat exchange. Although the heat exchanger is installed in the inner tank for direct heat exchange, which eliminates the need for a pump, it will cause the temperature of the inner tank to continue to drop, resulting in unstable water outlet temperature. Even if a thermostatic valve is installed, constant temperature control will be relatively troublesome. In addition, due to the heat exchange temperature difference, when water flows, the temperature of water flowing out of the heat exchanger is always lower than the heat exchange medium in the inner tank. It may even be dozens of degrees lower when there is no forced convection. When the water flow stops, the heat storage medium in the inner tank has enough time to keep the water in the heat exchanger at the same temperature. At this time, as soon as the user turns on the shower, a stream of very hot hot water will come out, which is a very bad experience and there is a risk of scalding. Thirdly, since the tap water in the heat exchanger will eventually reach the same temperature as the heat storage medium in the inner tank, it will cause scale to form in the flow channel of the heat exchanger where the tap water flows, making it impossible to use normally soon. The external circulation heat exchange system shown in Figure 1 does not have these issues. When the water supply is shut off, the temperature of the hot medium in the heat exchanger and the cold tap water is averaged, generally maintaining a temperature below 50°C. Furthermore, the heat exchanger dissipates heat outward, preventing scaling. In Figure 1, pump 6 is installed at the outlet of the heat exchanger. This ensures that the heat storage medium flowing through the pump is at a lower temperature after releasing heat. Installing pump 6 at the inlet of the heat exchanger 5 is also within the scope of the present invention, but this installation exposes the pump to high temperatures, which is detrimental to the high-speed rotating impeller, magnets, and electronic components. The heat storage medium in the inner tank cools significantly after releasing heat energy through heat exchanger 5. A high-performance heat exchanger can reduce the temperature of the hot water to only a few degrees above the cold water inlet of the water heater. Therefore, installing the pump at the outlet of the heat exchanger 5 is a better option. The heat storage heating unit 4 is installed in the inner tank 2 to heat the heat storage medium. The heat storage medium can be water or other liquids such as oil.Temperature sensors 9 are installed on the water outlet 15 and in the inner tank 2 for sensing the temperature of the inner tank and the water outlet; the water flow switch 8 can be installed at any position in the entire instant heating channel, for example, it can also be set on the water outlet 15 to sense the water flow state; as shown by the dotted line in Figure 1, the water flow switch, temperature sensor, pump, instant heating unit, and heat storage heating unit are connected to the control unit 7 through wires. Under special circumstances, some components can also be wirelessly connected using electromagnetic waves and mechanical waves. The control unit intelligently controls the pump, instant heating unit, and heat storage heating unit as actuators according to the working mode, water flow state, and temperature parameters set by the water heater.

[0056] The inner liner 2 can be a pressure-bearing or non-pressure-bearing structure. If a pressure-bearing structure is adopted, a pressure relief device needs to be installed on the inner liner. A non-pressure-bearing structure needs to have a hole opened to connect to the atmosphere. Both pressure-bearing and non-pressure-bearing inner liner can be filled with heat storage medium manually or automatically. Manual filling can be done by opening a filling hole on the inner liner and injecting from the filling hole; or a manual valve can be set, one end of the valve is connected to the inner liner and the other end is connected to tap water. The valve is opened manually to add water, and the valve is closed after visual filling. Automatic filling can be done by setting a solenoid valve or a stepper motor-driven valve between the tap water and the inner liner, which is controlled by the control unit 7. Automatic filling can only inject tap water as the heat storage medium. The heat storage heating unit 4 can be a resistance heater or an electromagnetic heater. The resistance heater can be installed inside the inner liner 2 to directly heat the heat storage medium, such as using an electric heating tube, or it can be attached to the outer wall of the inner liner for indirect heating, such as a cast aluminum heating plate. The electromagnetic induction coil of the electromagnetic heating device can only be set outside the inner liner.

[0057] The water heater in Figure 1 can have at least two heating modes, an instant heating mode and a rapid heating mode. When the instant heating mode is used, the heat storage heating unit 4 and the pump 6 do not work. At this time, the cold water entering the water heater will not obtain heat through the heat exchanger, and the tap water will only be heated by the instant heating unit 3. The control unit 7 can control the power of the instant heating unit to adjust the temperature of the outlet water. When the rapid heating mode is used, the heat storage heating unit 4 will heat the heat storage medium in the inner tank. When the water flow switch 8 senses that there is water flowing, the pump 6 starts, extracts the heat storage medium in the inner tank, and preheats the tap water flowing through the heat exchanger through the heat exchanger 5. The preheated tap water is then heated again by the instant heating unit 3 and flows out. The rapid heating mode is used when the tap water temperature is low and the water heater cannot meet the bathing requirements by using only instant heating. These two heating modes are equivalent to combining the advantages of storage type and instant heating type. When the tap water temperature is high, the heat storage medium in the inner tank does not need to store heat and can be used immediately after it is turned on, avoiding the heat dissipation loss of the storage water heater; when the tap water temperature is low, the heat energy stored in the inner tank can be utilized, so that the instant heating unit only uses lower power to meet the bathing requirements of large water volume, solving the problem of high power and small water volume of instant water heaters; at the same time, since the instant heating unit of appropriate power plays a leading role, the capacity of the inner tank can also be greatly reduced. Its capacity is only needed to assist the instant heating when the tap water temperature is low, making the water heater more beautiful and heating faster, so that multiple people can take turns bathing.

[0058] Scaling of storage water heaters is a major industry problem. A large amount of scale accumulates in the inner tank, which greatly affects water hygiene and the life of the electric heating tube. It also increases energy consumption and reduces the effective capacity of the water heater, bringing various adverse effects. The heat exchange structure shown in Figure 1 can effectively solve this problem: 1. The inner tank 2 and the heat storage heating unit 4 will not produce scale. For a 30-liter water heater using the technology of the present invention, even if the heat storage medium in the inner tank is water with serious scale, since the water in the inner tank is not discharged and used, it is only used as a heat storage medium. After filling it up, only the evaporated water needs to be replenished. During the service life of about 8 years, the water entering the inner tank is expected to be about 80 liters, which is like the amount of scale generated by one use of an ordinary 80-liter water storage type, which is negligible; 2. The heat exchanger 5 is also difficult to scale. The temperature of the heat storage medium from the inner tank flowing through the heat exchanger is high, but for the same reason as the inner tank, the scale is negligible; the tap water flowing through the heat exchanger is low in temperature and has a fast flow rate, which cannot meet the conditions for scaling; 3. If the instant heating unit 3 uses a cast aluminum heater, according to more than ten years of experience in the instant water heater industry, scale will not be generated either. Heat exchange is also widely used in water heaters. For example, a multi-mode water heater adopts a heat exchange method. However, since the heat exchanger is placed in the inner tank, scaling occurs in the heat exchange tubes, causing the heat exchanger to lose its heat exchange function and even clogging the heat exchanger. At the same time, placing the heat exchanger in the inner tank also causes the problem of scalding water when the water is turned off and then on again, which seriously affects the user experience. Even if a thermostatic valve is used, the constant temperature process is prolonged, resulting in a poor experience. Placing the heat exchanger in the inner tank causes the overall temperature of the inner tank to continue to drop, causing the outlet water temperature of the water heater to continue to drop, requiring frequent adjustment of the hot and cold water mixing ratio. Placing the heat exchanger in the inner tank also causes inconvenience in maintenance. The present invention places the heat exchanger outside the inner tank. Although a pump is added, it fully solves the above problems. At the same time, the outlet water temperature of the water heater can be controlled by adjusting the flow of the pump, so that the water heater does not need a thermostatic valve to adjust the temperature. The cost of the increased pump is offset by the thermostatic valve, so this solution is extremely cost-effective.

[0059] Pump 6 can be a speed-adjustable pump or a conventional non-speed-adjustable pump. If the speed cannot be adjusted, the outlet water temperature of the water heater cannot be controlled by adjusting the flow rate, or the outlet water temperature can only be controlled by adding a flow regulating valve to adjust the flow rate of the heat storage medium. Of course, if the flow rate of the pump is not adjusted in the rapid heating mode, the outlet water temperature can also be adjusted by controlling the power of the instant heating unit 3 or the flow rate of tap water. However, this method will reduce the hot water output of the water heater because the power of the instant heating unit cannot be fully utilized; or it may not be adaptable to different water pressures. For example, if a suitable pump flow rate is fixed, when the user's tap water pressure is high, the tap water flow rate is large, and the tap water after heat exchange cannot reach the set outlet water temperature even if it is heated by the instant heating unit at full power. At this time, the user only needs to manually reduce the flow rate. This situation is also the same when the water supply is multi-way. If the pump can adjust the flow rate, then it only needs to increase the pump flow rate. Therefore, when the heat exchanger is required to preheat the tap water in the rapid heating mode, it is a better solution to control the water outlet temperature of the water heater by adjusting the flow of the pump, so that the instant heating unit 3 can be at maximum power. At this time, under a certain flow rate and water outlet temperature, the flow rate of the heat storage medium pumped out by the pump from the inner tank is the smallest, so the water use time is long and the hot water output is the largest. Example

[0060] The inner container of this embodiment is connected to the atmosphere and includes a liquid level sensing unit 10 and a water supply valve 11. The liquid level sensing unit is mounted on the inner container or a component connected to the inner container to sense the liquid level. The inner container is connected to the instant heating channel via the water supply valve. The inner container also includes a heat conducting plate 21 and a temperature control switch 22. The ends of the heat conducting plate are thermally coupled to the instant heating unit 3 and the heat storage heating unit 4 or the inner container 2, respectively. The temperature control switch is mounted on the heat conducting plate.

[0061] As shown in Figure 2, the inner tank 2 is equipped with a vent 19 that connects to the atmosphere. A liquid level sensor 10 is located at the top of the tank to sense the level of the heat storage medium within the tank. This sensor transmits a signal to the control unit 7, providing one or more of the following functions: prompting, controlling automatic water refilling, and preventing dry boiling. In Figure 2, a water fill valve 11 is connected to the water inlet 14 at one end and the heat exchanger 5 at the other. The connection to the heat exchanger should be positioned to facilitate the removal of air from the heat exchanger and pump 6. Excessive air may prevent the pump 6 from pumping the heat storage medium from the inner tank. The purpose of the water fill valve 11 is to add water to the inner tank 2. It can be either a manual or automatic valve. If a manual valve is used, the liquid level sensor 10 can notify the user to add water by means of sound or light when the liquid level is too low. If an automatic valve is used, the water fill valve 11 automatically refills the tank when the liquid level sensor 10 detects a low liquid level and automatically shuts off when the liquid level is full. The installation position of the water supply valve only needs to connect the inner tank to the tap water, but if it is connected to the rear end of the water flow switch 8, the water flow switch will also sense the water flow when the inner tank is replenished with water, which will be confused with the user's water use. If the instant heating unit is started at this time, it will cause dry burning. This problem can be avoided through software design. For example, when the liquid level sensing unit senses that the liquid level is low, the instant heating unit will not work.

[0062] As shown in Figure 2, heat exchanger 5 comprises a heat exchanger shell 501 and heat exchange tubes 502. This is a shell-and-tube heat exchanger. This type of heat exchanger has a simple structure and low cost, but its heat transfer efficiency is poor due to laminar flow. It is inferior to a shell-and-tube heat exchanger, which is also a shell-and-tube heat exchanger. However, this type of heat exchanger is more expensive and similarly has low heat transfer efficiency due to laminar flow, but it is significantly better than the heat exchanger shown in the figure. For performance, economy, and compactness, a plate heat exchanger can be used. The schematic diagram of the present invention is for simplicity and clarity only, so the simplest shell-and-tube heat exchanger is used as a schematic diagram and is not intended to limit the present invention.

[0063] As shown in Figure 3, it also includes a liquid level tube 18, in which the liquid level sensing unit 10 is installed, and the liquid level tube is connected to the inner tank 2. This structure means that the liquid level sensing unit does not need to withstand the high temperature of the inner tank, making the component more reliable and having a longer life. The liquid level sensor in Figure 3 uses a float switch, which uses a magnet to act on a reed switch or a Hall switch to achieve liquid level sensing. Such float switches all achieve electrical isolation and can meet the protection requirements of Class II electrical appliances, but the float switch may have problems such as the float getting stuck or the reed switch or Hall element failing, and there is also the problem of magnet demagnetization. If the liquid level sensor uses electrode sensing as shown in Figure 4, it is simpler and more reliable than a float switch, but the disadvantage of electrode sensing is that there may be a risk of leakage. Although the electrode uses a few volts of weak electricity, there may also be a risk of leakage due to transformer damage, strong and weak current bridging, or lightning strikes. As shown in FIG4 , a slender and insulated connecting tube 20 is added, so that a sufficiently large resistor composed of heat storage medium is connected in series between the inner tank and the liquid level sensing unit, so that even if the liquid level sensing unit 10 is charged with a voltage of 220 volts, it will not pose a safety hazard to the user.

[0064] As shown in Figure 2, the water heater of the present invention includes two heaters, an instant heating unit and a heat storage heating unit. From a safety perspective, the electronic components may fail, and the contacts of the relay may spark and weld, thereby causing the temperature control to fail. Therefore, a manually reset mechanical temperature control switch needs to be provided on each heater or the inner tank associated with the heater to prevent the heating from getting out of control, which is used as the last line of defense when the electronic components fail. However, if two temperature control switches are installed, not only the cost increases, but the failure rate also increases exponentially. Therefore, as shown in Figure 2, a heat conducting plate 21 is utilized to directly or indirectly connect the two heaters, and a temperature control switch 22 is installed on the heat conducting plate. In this way, if the temperature of any one of the two heating units is too high, the temperature control switch will play a protective role. Of course, the heat conducting plate is connected to one end of the heat storage heating unit 4, and can also be connected to the inner tank, as long as the temperature is well transmitted.

[0065] A temperature sensor 9 is installed on the water inlet end 14 of Figure 2 for sensing the inlet temperature of tap water. According to the inlet temperature, the water heater can automatically determine whether to use instant heating or rapid heating mode, to what degree the inner tank temperature is heated, and whether the pump is started, thereby achieving more intelligent control.

[0066] As shown in Figure 5, the system also includes a flow regulating valve 16, which is located in the circulating heat exchange channel. The control unit controls the opening of the flow regulating valve to control the pump flow rate, thereby controlling the outlet water temperature of the water heater. When regulating the flow rate using a speed regulating pump is inaccurate or uneconomical, a valve can be used to adjust the flow rate to achieve the purpose of regulating the outlet water temperature. Example

[0067] The water heaters in the above two embodiments require a new control method to better utilize the technical advantages brought by the structural innovation. This embodiment introduces a control method. First of all, it should be stated that the control method in this invention only controls the structural innovation part of the present invention and does not include a complete control method for the water heater. As shown in Figure 6, the control method includes but is not limited to the following steps:

[0068] Obtain one or more of the water heater's operating mode, temperature, and water flow status information;

[0069] Determine whether the pump needs to be started based on the acquired parameters;

[0070] If so, the outlet water temperature is controlled by controlling the pump flow rate;

[0071] If not, the outlet water temperature is controlled by controlling the power of the instant heating unit.

[0072] The working modes of the water heater of the present invention may include intelligent mode, instant heating mode, and rapid heating mode. The intelligent mode automatically selects the instant heating mode or the rapid heating mode according to the inlet water temperature and automatically sets the temperature of the inner tank. Therefore, the intelligent mode is not displayed in Figure 7.

[0073] The following describes a more specific control method. The liquid level control and low-liquid-level protection methods are omitted as they are beyond the scope of this invention. As shown in Figure 7 , Tn is the actual tank temperature, Tns is the set tank temperature, Tc is the actual outlet water temperature, Tcs is the set outlet water temperature, Tj is the inlet water temperature, and a is an arbitrary real number.

[0074] S201: After the water heater is powered on, first obtain the working mode of the water heater. If it is instant heating mode, execute S202; if it is rapid heating mode, execute S212;

[0075] S202, instant heating mode, execute S203;

[0076] S203, determine whether there is water flowing in the water heater, if there is water flowing, execute S204, if there is no water flowing, execute S205;

[0077] S204, determine whether the instant heating unit is already in working state, if so, execute S207; if not, execute S206; since the parameters of the water heater are in dynamic change, for example, the user may adjust the water heater working mode, water outlet temperature, tap water may suddenly stop, etc. during operation, so the program is always in a loop state, and can respond in time when the parameters change. Step S204 is to determine whether it is the first cycle of the water heater or a subsequent cycle. If it is the first time, the instant heating unit needs to be started. If it is a subsequent cycle, it is only necessary to consider whether the power needs to be adjusted to make the water outlet temperature close to the set water outlet temperature.

[0078] S205: Stop the instant heating unit and then execute S208; if the instant heating unit is originally in the off state, maintain the off state.

[0079] S206, start the instant heating unit, and then execute S207;

[0080] S207: Compare whether the actual outlet water temperature is lower than the set outlet water temperature. If yes, execute S209 to increase the power of the instant heating unit. If no, execute S210 to compare whether the actual outlet water temperature is higher than the set outlet water temperature.

[0081] S208, execute S201, return to the program starting position and start the next cycle;

[0082] S209. Increase the power of the instant heater. How much to increase it at a time depends on the actual test results and is also related to the time interval between two program cycles. In short, the thermal lag problem must be taken into account. After the heater adjusts the power, it will take a certain amount of time for the water temperature to rise. Therefore, if the cycle speed is fast, the wattage of the power should be low each time it is adjusted. Otherwise, the water temperature will be hot and cold, and it will never be adjusted to the right temperature.

[0083] S210, compare whether the actual outlet water temperature is greater than the outlet water set temperature. If so, execute S211 to reduce the power of the instant heating unit; if not, execute S228; in S207, it has been compared whether it is less than, and in S210, it is compared whether it is greater than. If both times are no, it must be equal, which proves that the current actual outlet water temperature is equal to the outlet water set temperature, and there is no need to adjust the power of the instant heating unit.

[0084] S211, reducing the power of the instant heating unit, and then executing S228;

[0085] S212, rapid heating mode, execute S213; the so-called rapid heating mode is a working mode in which the inner tank of the water heater needs to store heat to provide auxiliary heat to the instant heating unit.

[0086] S213, determining whether water is flowing in the water heater, if so, executing S215, if not, executing S214;

[0087] S214, turn off the pump and the instant heating unit; if the pump and the instant heating unit are already in the off state, maintain the off state and then execute S217;

[0088] S215: Determine whether the inner tank temperature is greater than the inlet water temperature plus a. If so, proceed to S218; if not, proceed to S216. Heat exchange is meaningful only when the inner tank temperature is somewhat higher than the inlet water temperature. The degree of this higher depends on the heat exchange efficiency of the heat exchanger, so a can be determined based on actual test data. If the inner tank temperature is too low, heat exchange is meaningless, and the pump will not start even in rapid heat mode. In this case, the instant heat mode program can be used to control the water heater.

[0089] S216, execute S204;

[0090] S217: Determine whether the inner tank temperature is less than the set inner tank temperature. If so, execute S224; if not, execute S221. In the actual control program, a should be added to whether the inner tank temperature is less than the set inner tank temperature. Otherwise, frequent heating will occur. For example, if the inner tank temperature is set to 80 degrees and the inner tank temperature drops below 75 degrees, heating will be repeated. This control method only provides the control logic of the water heater based on the present invention and does not involve the details of the actual program.

[0091] S218. Determine whether the instant heating unit is already in operation. If so, execute S220; if not, execute S219. If the instant heating unit is not started at this step, it proves that the program is in the first cycle after the water flow is turned on, and the pump must not be started at this time. If the instant heating unit is already started at this step, it proves that it is not the first cycle. At this time, it only needs to consider whether the outlet water temperature is equal to the set outlet water temperature.

[0092] S219. Start the pump and the instantaneous heating unit. Generally, in rapid heating mode, the instantaneous heating unit operates at its maximum power setting upon startup. This maximum power setting is the power set by the user. For example, some users may set the power lower due to concerns about line load. If no setting is set, the rated power, or the maximum power of the water heater, is used. Of course, considering operating at maximum power during startup is solely for the purpose of increasing hot water output. It is desirable to operate the instantaneous heating unit at maximum power, and by adjusting the pump flow rate to control the outlet water temperature, this minimizes the amount of heat drawn from the inner tank, thus extending the service life. If hot water output is not a concern, this consideration is unnecessary, and the pump flow rate does not need to be adjusted. In rapid heating mode, the outlet water temperature is adjusted by adjusting the power of the instantaneous heating unit. Even maintaining a constant outlet water temperature is unnecessary; the user can adjust the water flow rate or the hot and cold water ratio, which falls within the scope of the present invention. This control method merely provides an optimal solution.

[0093] S220, determining whether the outlet water temperature is lower than the set outlet water temperature, if so, executing S223 to increase the pump flow rate; if not, executing S222;

[0094] S221, turn off the heat storage and heating unit, and then execute S228;

[0095] S222. Determine whether the outlet water temperature is greater than the outlet water set temperature. If so, execute S225; if not, execute S228. If the results of the comparisons in steps S220 and S222 are both no, the actual outlet water temperature must be equal to the outlet water set temperature. The program does not need to perform temperature adjustment operations and can directly return to the next cycle.

[0096] S223, increase the flow rate of the pump, and then execute S228; the size of each increase or decrease in the flow rate of the pump must also be determined according to the speed of the program cycle, otherwise the outlet water temperature will fluctuate due to the thermal feedback delay of the heat exchange system and the temperature sensor and cannot be stable.

[0097] S224, starting the heat storage heating unit; starting the heat storage heating unit is to heat the heat storage medium of the inner tank.

[0098] S225. Determine whether the pump has been started. If so, execute S227 to reduce the pump flow; if not, execute S226 to reduce the power of the instant heating unit. The purpose of this step is that if the pump flow has been shut down and the outlet water temperature is still high, the outlet water temperature can only be controlled by reducing the power of the instant heating unit.

[0099] S226, execute S211;

[0100] S227, reduce the flow rate of the pump;

[0101] S228. Execute S201.

[0102] The above control method is only one of many available control methods. More specific control methods can be designed based on the flowchart of FIG6 , all of which are within the protection scope of the present invention.

[0103] The above examples are not exhaustive of all structures and methods. All combinations of the above solutions, any solutions that can be easily thought of through the present invention, and any modified solutions are within the scope of protection of this patent.

Claims

1. A water heater, comprising a housing (1), an inner tank (2), an instant heating unit (3), a heat storage unit (4), a water flow switch (8), a control unit (7), a temperature sensor (9), a water inlet (14), and a water outlet (15), characterized in that: It also includes a heat exchanger (5) and a pump (6); the water inlet, heat exchanger, instant heating unit, and water outlet are connected in sequence to form an instant heating channel; the heat exchanger, pump, and inner tank are connected to form a circulating heat exchange channel; the heat storage heating unit is used to heat the heat storage medium in the inner tank; and the control unit controls the working state of the instant heating unit, the heat storage heating unit, and the pump according to one or more of the working mode of the water heater, the water flow state, and the temperature.

2. A water heater according to claim 1, characterized in that: The inner pot is connected to the atmosphere and further comprises a liquid level sensing unit (10) and a water supply valve (11); the liquid level sensing unit is arranged on the inner pot or a component connected to the inner pot and is used to sense the liquid level of the inner pot; the inner pot is connected to the instant heating channel via the water supply valve.

3. A water heater according to claim 2, characterized in that: The water supply valve (11) is connected to the inner tank via the heat exchanger and is used to remove air from the heat exchanger and the pump when water is supplied.

4. A water heater according to claim 2, characterized in that: It also includes a liquid level tube (18), wherein the liquid level sensing unit is installed in the liquid level tube, and the liquid level tube is in communication with the inner container (2).

5. A water heater according to claim 1, characterized in that: It also comprises a heat conducting sheet (21) and a temperature control switch (22), wherein two ends of the heat conducting sheet are thermally coupled to the instant heating unit (3) and the heat storage heating unit (4) or the inner tank (2), respectively, and the temperature control switch is mounted on the heat conducting sheet.

6. A water heater according to claim 1, characterized in that: The control unit (7) comprises a speed regulating module, and the control unit controls the speed of the pump according to the temperature parameter of the water heater to adjust the outlet water temperature.

7. A water heater according to claim 1, characterized in that: It also comprises a flow regulating valve (16), which is arranged on the circulating heat exchange channel, and the control unit controls the opening of the flow regulating valve to control the flow of the pump, thereby controlling the outlet water temperature of the water heater.

8. A water heater according to claim 1, characterized in that: The pump (6) is arranged at one end of the water outlet of the heat exchanger (5).

9. A control method for a water heater according to any one of claims 1 to 8, characterized in that: The control method comprises: Obtain one or more of the water heater's operating mode, temperature, and water flow status information; Determine whether the pump needs to be started according to the acquired parameters; If so, the outlet water temperature is controlled by controlling the pump flow rate; If not, the outlet water temperature is controlled by controlling the power of the instant heating unit.

10. A control method according to claim 9, characterized in that: The water heater parameters include one or more of the working mode, water flow switch state, water inlet temperature, water tank temperature, and water outlet setting temperature, and the control method thereof includes the following steps: Step 1: Get the working mode of the water heater. If it is instant heating mode, go to step 2; if it is quick heating mode, go to step 9; Step 2: Is the water flow switch activated? If yes, proceed to step 3; if no, proceed to step 22; Step 3: Is the instant heating unit started? If yes, go to step 5; if no, go to step 4; Step 4, the instant heating unit is started, and then step 5 is performed; Step 5. Is the outlet water temperature lower than the set outlet water temperature? If yes, proceed to step 6; if no, proceed to step 7; Step 6: Increase the power of the instant heating unit, and then execute step 1; Step 7. Is the outlet water temperature greater than the set outlet water temperature? If yes, proceed to step 8; if no, proceed to step 1; Step 8, reduce the power of the instant heating unit, and then execute step 1; Step 9. Is the water flow switch activated? If yes, proceed to step 10; if no, proceed to step 18; Step 10: Is the inner tank temperature greater than the inlet water temperature plus a? If yes, go to step 11; if no, go to step 3; Step 11: Is the instant heating unit working? If yes, go to step 13; if no, go to step 12; Step 12, the pump and the instant heating unit work, and then execute step 13; Step 13: Is the outlet water temperature lower than the set outlet water temperature? If yes, go to step 14; if no, go to step 15; Step 14: Increase the pump flow rate, and then execute step 1; Step 15. Is the outlet water temperature greater than the set outlet water temperature? If yes, go to step 16; if no, go to step 1; Step 16: Is the pump started? If yes, go to step 17; if no, go to step 8; Step 17, reduce the pump flow, and then execute step 1; Step 18, the pump and the instant heater stop working, and then execute step 19; Step 19: Is the inner tank temperature lower than the inner tank set temperature? If yes, go to step 20; if no, go to step 21; Step 20, the heat storage and heating unit works, and then executes step 1; Step 21, the heat storage and heating unit stops working, and then executes step 1; Step 22: the heating unit stops working, and then executes step 1.

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