Water heater

Abstract

The utility model discloses a water heater, which relates to the technical field of hot water equipment, and comprises a water heater main body, a water inlet pipeline, a water outlet pipeline, a burner and a main heat exchanger, the water inlet end of the main heat exchanger is communicated with the water inlet pipeline, the water outlet end of the main heat exchanger is communicated with the water outlet pipeline, and the burner is communicated with the water outlet pipeline. The combustor is used for combusting to generate flue gas so as to exchange heat with water in the main heat exchanger; the front heat exchanger is provided with a first heat exchange channel and a second heat exchange channel, the first heat exchange channel communicates with the water inlet pipeline, the second heat exchange channel communicates with the water outlet pipeline, and the front heat exchanger is used for conducting heat exchange on water in the water inlet pipeline and water in the water outlet pipeline. According to the technical scheme, condensate water can be reduced, and the service life of the water heater is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of hot water equipment technology, and in particular to a water heater. Background Technology

[0002] Existing gas water heaters typically produce condensate during operation, especially in cold winters when the inlet water temperature is low. This results in a large amount of condensate forming on the heat exchanger surface. When the condensate mixes with the flue gas, it becomes acidic. This acidic condensate drips into the machine and corrodes internal components (such as the burner and fan), affecting the water heater's lifespan. Utility Model Content

[0003] The main purpose of this utility model is to propose a water heater that can reduce condensate production and extend the service life of the water heater.

[0004] To achieve the above objectives, the water heater proposed in this utility model includes:

[0005] The water heater body includes an inlet pipe, an outlet pipe, a burner, and a main heat exchanger. The inlet end of the main heat exchanger is connected to the inlet pipe, and the outlet end of the main heat exchanger is connected to the outlet pipe. The burner is used to generate flue gas for heat exchange with the water in the main heat exchanger.

[0006] The front heat exchanger has a first heat exchange channel and a second heat exchange channel. The first heat exchange channel is connected to the inlet water pipe, and the second heat exchange channel is connected to the outlet water pipe. The front heat exchanger is used to exchange heat between the water in the inlet water pipe and the water in the outlet water pipe.

[0007] In one embodiment, the inlet pipe, the outlet pipe, and the pre-exchange heat exchanger are connected to form a heat exchange pipe system. The water heater further includes a switching device disposed in the heat exchange pipe system. The switching device is used to control the water in the inlet pipe to be transported to the main heat exchanger after heat exchange with the water in the outlet pipe via the pre-exchange heat exchanger in a first state. The switching device is also used to control the water in the inlet pipe to be transported directly to the main heat exchanger without participating in heat exchange or to control the water in the outlet pipe to be output directly without participating in heat exchange in a second state.

[0008] In one embodiment, the water heater further includes an inlet water temperature sensor that is communicatively connected to the switching device. The inlet water temperature sensor is located in the inlet pipe and upstream of the first heat exchange channel in the water inlet direction. The switching device is used to switch between the first state and the second state according to the inlet water temperature.

[0009] And / or, the water heater further includes an outlet water temperature sensor that is communicatively connected to the switching device. The outlet water temperature sensor is located in the outlet pipe and downstream of the second heat exchange channel in the outlet direction. The switching device is used to switch between the first state and the second state according to the outlet water temperature.

[0010] In one embodiment, the front heat exchanger is configured as a plate heat exchanger or a shell-and-tube heat exchanger.

[0011] In one embodiment, the inlet end of the first heat exchange channel is connected to the inlet pipeline through a first bypass port, and the outlet end of the first heat exchange channel is connected to the inlet pipeline through a second bypass port. The first bypass port is located upstream of the second bypass port in the water inlet direction.

[0012] In one embodiment, the water inlet pipeline includes a first water inlet pipe section, a second water inlet pipe section, and a third water inlet pipe section connected sequentially along the water inlet direction. A first bypass port is provided at the connection between the first water inlet pipe section and the second water inlet pipe section, and a second bypass port is provided at the connection between the second water inlet pipe section and the third water inlet pipe section. The first heat exchange channel is connected in parallel with the second water inlet pipe section between the first bypass port and the second bypass port.

[0013] The water heater also includes a switching device, which is used to control the water in the inlet pipe to be transported to the main heat exchanger after exchanging heat with the water in the outlet pipe via the pre-heat exchanger in the first state, and to control the water in the inlet pipe to be transported directly to the main heat exchanger without participating in heat exchange in the second state.

[0014] In one embodiment, the switching device is configured as a three-way valve, the first inlet pipe section and the second inlet pipe section are connected through the three-way valve, the first bypass port is provided at the three-way valve, and the three-way valve is used to control the first inlet pipe section to selectively connect to the first heat exchange channel and / or the second inlet pipe section;

[0015] Alternatively, the switching device is configured as a three-way valve, the second inlet pipe section and the third inlet pipe section are connected through the three-way valve, the second bypass port is provided at the three-way valve, and the three-way valve is used to control the third inlet pipe section to selectively connect to the first heat exchange channel and / or the second inlet pipe section;

[0016] Alternatively, the switching device includes a first switching valve and a second switching valve; the first switching valve is located in the second inlet pipe section; the second switching valve is located in the first heat exchange channel, or in the pipeline between the inlet end of the first heat exchange channel and the first bypass port, or in the pipeline between the outlet end of the first heat exchange channel and the second bypass port.

[0017] In one embodiment, the inlet end of the second heat exchange channel is connected to the outlet pipe through a third bypass port, and the outlet end of the second heat exchange channel is connected to the outlet pipe through a fourth bypass port. The third bypass port is located upstream of the fourth bypass port in the outlet direction.

[0018] In one embodiment, the water outlet pipeline includes a first water outlet pipe section, a second water outlet pipe section, and a third water outlet pipe section connected sequentially along the water outlet direction. The third bypass port is provided at the connection between the first water outlet pipe section and the second water outlet pipe section, and the fourth bypass port is provided at the connection between the second water outlet pipe section and the third water outlet pipe section. The second heat exchange channel is connected in parallel with the second water outlet pipe section between the third bypass port and the fourth bypass port.

[0019] The switching device is used to control the water in the inlet pipe to be transported to the main heat exchanger after exchanging heat with the water in the outlet pipe via the preheater in the first state, and to control the water in the outlet pipe to be directly output without participating in heat exchange in the second state.

[0020] In one embodiment, the switching device is configured as a three-way valve, the first outlet pipe section and the second outlet pipe section are connected through the three-way valve, the third bypass port is provided at the three-way valve, and the three-way valve is used to control the first outlet pipe section to selectively connect to the second heat exchange channel and / or the second outlet pipe section;

[0021] Alternatively, the switching device is configured as a three-way valve, the second outlet pipe section and the third outlet pipe section are connected through the three-way valve, the fourth bypass port is provided at the three-way valve, and the three-way valve is used to control the third outlet pipe section to selectively connect to the second heat exchange channel and / or the second outlet pipe section;

[0022] Alternatively, the switching device includes a first switching valve and a second switching valve; the first switching valve is located in the second outlet pipe section; the second switching valve is located in the second heat exchange channel, or in the pipeline between the inlet end of the second heat exchange channel and the third bypass port, or in the pipeline between the outlet end of the second heat exchange channel and the fourth bypass port.

[0023] The technical solution of this utility model involves connecting a front heat exchanger between the inlet and outlet pipes of the water heater body. The water heater body includes an inlet pipe, an outlet pipe, a burner, and a main heat exchanger. Cold water is transported to the main heat exchanger via the inlet pipe, where it exchanges heat with the high-temperature flue gas generated by the burner, thus producing hot water. The hot water is then output via the outlet pipe. The front heat exchanger has a first heat exchange channel and a second heat exchange channel. The first heat exchange channel connects to the inlet pipe, and the second heat exchange channel connects to the outlet pipe, allowing cold water from the inlet pipe to enter the water heater. The water enters the first heat exchange channel and then flows to the main heat exchanger. The hot water in the main heat exchanger can be transported to the second heat exchange channel through the outlet pipe. In this way, the hot water in the second heat exchange channel exchanges heat with the cold water in the first heat exchange channel. This allows the water in the inlet pipe and the water in the outlet pipe to exchange heat through the front heat exchanger, thereby increasing the inlet water temperature delivered to the main heat exchanger. This reduces the temperature difference between the flue gas and the surface of the main heat exchanger, reduces condensate production, and prevents excessive condensate from causing serious corrosion to other internal components of the machine, thus extending the service life of the water heater. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0025] Figure 1 A schematic diagram of the structure of the first embodiment of the water heater provided by this utility model;

[0026] Figure 2 for Figure 1 A schematic diagram of the water flow direction when the switching device of the medium-sized water heater is in the first state;

[0027] Figure 3 for Figure 1 A schematic diagram of the water flow direction when the switching device of the medium-sized water heater is in the second state;

[0028] Figure 4 A schematic diagram of the structure of the second embodiment of the water heater provided by this utility model;

[0029] Figure 5 A schematic diagram of the structure of the third embodiment of the water heater provided by this utility model;

[0030] Figure 6 A schematic diagram of the structure of the fourth embodiment of the water heater provided by this utility model;

[0031] Figure 7A schematic diagram of the fifth embodiment of the water heater provided by this utility model;

[0032] Figure 8 for Figure 7 A schematic diagram of the water flow direction when the switching device of the medium-sized water heater is in the first state;

[0033] Figure 9 for Figure 7 A schematic diagram of the water flow direction when the switching device of the medium-sized water heater is in the second state;

[0034] Figure 10 A schematic diagram of the sixth embodiment of the water heater provided by this utility model;

[0035] Figure 11 A schematic diagram of the structure of the seventh embodiment of the water heater provided by this utility model;

[0036] Figure 12 This is a structural schematic diagram of the eighth embodiment of the water heater provided by this utility model.

[0037] Explanation of icon numbers:

[0038] 100. Water heater; 10. Water heater body; 11. Inlet pipe; A. First bypass port; B. Second bypass port; 111. First inlet pipe section; 112. Second inlet pipe section; 113. Third inlet pipe section; 12. Outlet pipe; C. Third bypass port; D. Fourth bypass port; 121. First outlet pipe section; 122. Second outlet pipe section; 123. Third outlet pipe section; 13. Burner; 14. Main heat exchanger 15. Fan; 20. Front heat exchanger; 21. First heat exchange channel; 21a. Water inlet of the first heat exchange channel; 21b. Water outlet of the first heat exchange channel; 22. Second heat exchange channel; 22a. Water inlet of the second heat exchange channel; 22b. Water outlet of the second heat exchange channel; 30. Switching device; 31. First switching valve; 32. Second switching valve; 40. Inlet water temperature sensor; 50. Outlet water temperature sensor.

[0039] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0040] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0041] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0042] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0043] Existing gas water heaters typically produce condensate during operation, especially in cold winters when the inlet water temperature is low. This results in a large amount of condensate forming on the heat exchanger surface. When the condensate mixes with the flue gas, it becomes acidic. This acidic condensate drips into the machine and corrodes internal components (such as the burner and fan), affecting the water heater's lifespan.

[0044] This utility model proposes a water heater 100 that can reduce condensate production and extend the service life of the water heater 100.

[0045] Please see Figure 1 In one embodiment of this utility model, the water heater 100 includes a water heater body 10 and a front heat exchanger 20. The water heater body 10 includes an inlet pipe 11, an outlet pipe 12, a burner 13, and a main heat exchanger 14. The inlet end of the main heat exchanger 14 is connected to the inlet pipe 11, and the outlet end of the main heat exchanger 14 is connected to the outlet pipe 12. The burner 13 is used to generate flue gas for heat exchange with the water in the main heat exchanger 14. The front heat exchanger 20 has a first heat exchange channel 21 and a second heat exchange channel 22. The first heat exchange channel 21 is connected to the inlet pipe 11, and the second heat exchange channel 22 is connected to the outlet pipe 12. The front heat exchanger 20 is used to exchange heat between the water in the inlet pipe 11 and the water in the outlet pipe 12.

[0046] In this embodiment, the water heater body 10 is used to realize the combustion and heat exchange functions of the water heater 100. The water heater body 10 includes an inlet pipe 11, an outlet pipe 12, a burner 13, and a main heat exchanger 14. When the water heater 100 is working, the high-temperature flue gas generated by the combustion of the burner 13 flows to the main heat exchanger 14. At the same time, cold water can be transported to the main heat exchanger 14 through the inlet pipe 11. The high-temperature flue gas exchanges heat with the water in the main heat exchanger 14 to heat the cold water entering the main heat exchanger 14. The hot water in the main heat exchanger 14 can be output to the water user through the outlet pipe 12 to provide the user with the hot water needed for daily life. In addition, the water heater body 10 also includes a fan 15, which drives the high-temperature flue gas generated by the combustion of the burner 13 to flow to the main heat exchanger 14 to accelerate the heat exchange between the flue gas and the main heat exchanger 14.

[0047] In practical applications, the water heater 100 has different models depending on the function of the fan 15 and the relative arrangement of the fan 15, burner 13, and main heat exchanger 14. For a forced-draft gas water heater 100, the air outlet of the fan 15 is connected to the burner 13, and the main heat exchanger 14 is arranged on the side of the burner 13 away from the fan 15. The fan 15 blows air into the burner 13 to provide the secondary air required for combustion, and also drives the high-temperature flue gas generated by the combustion of the burner 13 to flow towards the main heat exchanger 14 for efficient heat exchange. For a forced-extraction gas water heater 100, the air inlet of the fan 15 faces the main heat exchanger 14, and the burner 13 is arranged on the side of the main heat exchanger 14 away from the fan 15. The fan 15 drives the high-temperature flue gas generated by the combustion of the burner 13 to flow towards the main heat exchanger 14 for efficient heat exchange. The flue gas after heat exchange enters the fan 15 and is then discharged from the air outlet of the fan 15. For a forward-firing gas water heater 100, the burner 13 is located at the bottom of the water heater body 10, and the flame generated by the burner 13 rises upward, while the flue gas flows upward to the main heat exchanger 14. For a reverse-firing gas water heater 100, the burner 13 is located at the top of the water heater body 10, and the flame generated by the burner 13 falls downward, while the flue gas flows downward to the main heat exchanger 14.

[0048] The following mainly uses the 100-type forced-fire gas water heater as an example. Figure 1As shown, the main body 10 of the water heater includes a fan 15, a burner 13, and a main heat exchanger 14 arranged from bottom to top. The fan 15 is used to blow air into the burner 13 and drive the flue gas generated by the combustion of the burner 13 to flow to the main heat exchanger 14. In addition, a gas proportional valve may be provided at the bottom of the burner 13 to control the amount of gas supplied to the burner 13; a combustion chamber box may be provided between the burner 13 and the main heat exchanger 14 to provide sufficient combustion space for the burner 13; a smoke hood may be provided at the top of the main heat exchanger 14, and the flue gas after heat exchange in the main heat exchanger 14 can be collected by the smoke hood and discharged outside the water heater 100.

[0049] It is understandable that when flue gas exchanges heat with the main heat exchanger 14, condensate will be generated on the surface of the main heat exchanger 14. Especially when the temperature of the inlet water supplied in the inlet pipe 11 is too low, the cold water at a lower temperature enters the main heat exchanger 14, resulting in a relatively low surface temperature of the main heat exchanger 14. The greater the temperature difference between the main heat exchanger 14 and the flue gas, the more condensate will be generated. Furthermore, the condensate mixed with the flue gas is acidic and corrosive. The condensate on the surface of the main heat exchanger 14 drips downwards under the action of gravity and falls onto components such as the burner 13 and the fan 15, causing corrosion of the burner 13 and the fan 15 and affecting the service life of the water heater 100.

[0050] To reduce condensate generation, the water heater 100 also includes a pre-heat exchanger 20, which is a liquid-liquid heat exchanger capable of transporting and exchanging heat between two liquids, including but not limited to plate heat exchangers and shell-and-tube heat exchangers. The pre-heat exchanger 20 has a first heat exchange channel 21 and a second heat exchange channel 22. The first heat exchange channel 21 is connected to the inlet pipe 11, allowing cold water in the inlet pipe 11 to enter the first heat exchange channel 21 and then flow to the main heat exchanger 14. The second heat exchange channel 22 is connected to the outlet pipe 12, allowing hot water in the main heat exchanger 14 to be transported to the second heat exchange channel 22 via the outlet pipe 12. In other words, the first heat exchange channel 21 is used to transport cold water, and the second heat exchange channel 22 is used to transport hot water. Water, thus, utilizes the hot water in the second heat exchange channel 22 to exchange heat with the cold water in the first heat exchange channel 21, enabling heat exchange between the water in the inlet pipe 11 and the water in the outlet pipe 12. This raises the temperature of the water in the inlet pipe 11 before it is delivered to the main heat exchanger 14, thereby increasing the inlet water temperature delivered to the main heat exchanger 14. This reduces the temperature difference between the flue gas and the surface of the main heat exchanger 14, reducing condensate production and preventing excessive condensate from causing severe corrosion to other internal components. The first heat exchange channel 21 can be connected in parallel or in series with the inlet pipe 11, and the second heat exchange channel 22 can be connected in parallel or in series with the outlet pipe 12. It is understood that the front heat exchanger 20 is only used for heat exchange between the water in the inlet pipe 11 and the water in the outlet pipe 12, and does not participate in heat exchange with the flue gas.

[0051] The technical solution of this utility model involves connecting a front heat exchanger 20 between the inlet pipe 11 and the outlet pipe 12 of the water heater body 10. The water heater body 10 includes an inlet pipe 11, an outlet pipe 12, a burner 13, and a main heat exchanger 14. Cold water is transported to the main heat exchanger 14 via the inlet pipe 11 to exchange heat with the high-temperature flue gas generated by the burner 13, thereby producing hot water. The hot water is then output via the outlet pipe 12. The front heat exchanger 20 has a first heat exchange channel 21 and a second heat exchange channel 22. The first heat exchange channel 21 connects to the inlet pipe 11, and the second heat exchange channel 22 connects to the outlet pipe 12, thus connecting the inlet pipe... The cold water in the inlet pipe 11 can enter the first heat exchange channel 21 and then flow to the main heat exchanger 14. The hot water in the main heat exchanger 14 can be transported to the second heat exchange channel 22 through the outlet pipe 12. In this way, the hot water in the second heat exchange channel 22 and the cold water in the first heat exchange channel 21 can exchange heat, and the water in the inlet pipe 11 and the water in the outlet pipe 12 can exchange heat through the front heat exchanger 20. This can increase the inlet water temperature delivered to the main heat exchanger 14, thereby reducing the temperature difference between the flue gas and the surface of the main heat exchanger 14, reducing the generation of condensate, and preventing excessive condensate from causing serious corrosion to other internal components of the machine, thus extending the service life of the water heater 100.

[0052] In practical applications, during cold winters when the inlet water temperature is low, the water in the inlet pipe 11 needs to be heated by the preheater 20 to reduce the generation of condensate; however, during hot summers when the inlet water temperature is high, it is not necessary to heat the water in the inlet pipe 11 by the preheater 20.

[0053] In order to better adapt to different application scenarios, such as Figures 1 to 12 As shown, in some embodiments, the inlet pipe 11, the outlet pipe 12, and the pre-exchange heat exchanger 20 are connected to form a heat exchange pipe system. The water heater 100 also includes a switching device 30 disposed in the heat exchange pipe system. The switching device 30 has a first state and a second state. In the first state, the switching device 30 is used to control the water in the inlet pipe 11 to be transported to the main heat exchanger 14 after exchanging heat with the water in the outlet pipe 12 via the pre-exchange heat exchanger 20. In the second state, the switching device 30 is used to control the water in the inlet pipe 11 to be transported directly to the main heat exchanger 14 without participating in heat exchange, or to control the water in the outlet pipe 12 to be output directly without participating in heat exchange.

[0054] In this embodiment, by setting the switching device 30 to switch between a first state and a second state, the water heater 100 can autonomously choose whether to allow the water in the inlet pipe 11 and the water in the outlet pipe 12 to exchange heat through the pre-heat exchanger 20. For example, when the inlet water temperature is low (e.g., below a first preset temperature), the switching device 30 is in the first state, and the switching device 30 can control the water in the inlet pipe 11 to exchange heat through the pre-heat exchanger 20 before being transported to the main heat exchanger 14, thereby increasing the inlet water temperature entering the main heat exchanger 14 and reducing the generation of condensate; when the inlet water temperature is high (e.g., above a second preset temperature), the switching device 30 is in the second state, and the switching device 30 controls the water in the inlet pipe 11 to not participate in heat exchange and be directly transported to the main heat exchanger 14.

[0055] It is worth noting that there are several ways to prevent the water in the inlet pipe 11 from participating in heat exchange by using the switching device 30. For example, the first heat exchange channel 21 can be connected in parallel with the inlet pipe 11, and the switching device 30 can be used to control the water flow direction so that the water in the inlet pipe 11 is directly delivered to the main heat exchanger 14 without passing through the first heat exchange channel 21; or the switching device 30 can be used to cut off the outlet end of the first heat exchange channel 21 so that the hot water after heat exchange in the first heat exchange channel 21 does not flow to the main heat exchanger 14. As another example, the second heat exchange channel 22 can be connected in parallel with the outlet pipe 12, and the switching device 30 can be used to control the water flow direction so that the water in the outlet pipe 12 is directly output without passing through the second heat exchange channel 22. In this case, no hot water flows through the second heat exchange channel 22, and therefore does not exchange heat with the cold water in the first heat exchange channel 21. The switching device 30 can be a three-way valve or a combination of multiple switching valves, as long as it can achieve the switching of the water path.

[0056] like Figure 1 As shown, in one embodiment, the water heater 100 further includes an inlet water temperature sensor 40 that is communicatively connected to the switching device 30. The inlet water temperature sensor 40 is located on the inlet water pipe 11 and upstream of the first heat exchange channel 21 in the water inlet direction. The switching device 30 is used to switch between the first state and the second state according to the inlet water temperature.

[0057] In this embodiment, the switching device 30 and the inlet water temperature sensor 40 can be electrically connected to the control system of the water heater 100 to achieve communication between the inlet water temperature sensor 40 and the switching device 30. When the water heater 100 is working, the inlet water temperature sensor 40 detects the inlet water temperature and feeds back the inlet water temperature signal to the control system. The control system determines whether the water in the inlet pipe 11 needs to be heated based on the inlet water temperature signal, and then sends a command to the switching device 30 based on the determination result to control the switching device 30 to switch between the first state and the second state. For example, when the inlet water temperature sensor 40 detects that the inlet water temperature is lower than the first preset temperature, it indicates that the inlet water temperature is very low, and a large amount of condensate is easily generated on the surface of the main heat exchanger 14. At this time, the switching device 30 switches to the first state (e.g., Figure 2 As shown), the water in the inlet pipe 11 is heat-exchanged by the preheater 20 before being transported to the main heat exchanger 14, thereby increasing the inlet water temperature entering the main heat exchanger 14 and reducing condensation. When the inlet water temperature sensor 40 detects that the inlet water temperature is higher than the second preset temperature, it indicates that the inlet water temperature is high and condensation is less likely to form on the surface of the main heat exchanger 14. At this time, the switching device 30 switches to the second state (as shown). Figure 3 As shown, the water in the inlet pipe 11 is directly transported to the main heat exchanger 14 without participating in heat exchange, so as to improve the efficiency of water delivery.

[0058] like Figure 7 As shown, in one embodiment, the water heater 100 further includes an outlet water temperature sensor 50 that is communicatively connected to the switching device 30. The outlet water temperature sensor 50 is located in the outlet pipe 12 and downstream of the second heat exchange channel 22 in the outlet water direction. The switching device 30 is used to switch between the first state and the second state according to the outlet water temperature.

[0059] In this embodiment, the switching device 30 and the outlet water temperature sensor 50 can be electrically connected to the control system of the water heater 100 to achieve communication between the outlet water temperature sensor 50 and the switching device 30. When the water heater 100 is working, the outlet water temperature sensor 50 detects the outlet water temperature and feeds back the outlet water temperature signal to the control system. The control system determines whether it is necessary to use the water in the outlet pipe 12 to exchange heat with the water in the inlet pipe 11 based on the outlet water temperature signal, and then sends a command to the switching device 30 based on the determination result to control the switching device 30 to switch between the first state and the second state. For example, when the outlet water temperature sensor 50 detects that the outlet water temperature is lower than the third preset temperature, it indicates that the outlet water temperature is low. If heat exchange is performed through the preheater 20, the outlet water temperature will be further reduced, which will affect the user's use of hot water. At this time, the switching device 30 can be switched to the second state (e.g., Figure 9(As shown), so that the water in the outlet pipe 12 is directly output without participating in heat exchange. When the outlet water temperature sensor 50 detects that the outlet water temperature is higher than the fourth preset temperature, it indicates that the outlet water temperature is high, and the hot water in the outlet pipe 12 can be used to heat the cold water in the inlet pipe 11. At this time, the switching device 30 can be switched to the first state (as shown). Figure 8 (As shown).

[0060] Optionally, the water heater 100 includes an inlet water temperature sensor 40 and an outlet water temperature sensor 50. The inlet water temperature sensor 40 is located in the inlet pipe 11 and upstream of the first heat exchange channel 21 in the water inlet direction. The outlet water temperature sensor 50 is located in the outlet pipe 12 and downstream of the second heat exchange channel 22 in the water outlet direction. The switching device 30 is used to switch between a first state and a second state according to the inlet water temperature and / or the outlet water temperature.

[0061] Optionally, the front heat exchanger 20 can be configured as a plate heat exchanger or a coaxial heat exchanger. For example, the front heat exchanger 20 can be a plate heat exchanger, which consists of a series of metal plates with a certain corrugated shape stacked together, forming thin rectangular channels between the plates for heat exchange. Because of its small flow channels and complex waveforms, the plate heat exchanger experiences significant turbulence when the fluid flows between the plates, achieving turbulence at very low flow velocities. Therefore, it has a high heat transfer coefficient and high heat exchange efficiency; furthermore, it has a large heat exchange area per unit volume, a small footprint, and allows for easy addition or removal of plates to adapt to different heat transfer area requirements. Alternatively, the front heat exchanger 20 can be a coaxial heat exchanger, which uses two standard tubes of different sizes connected to form a concentric circular shell, with the outer side called the shell side and the inner side called the tube side. The two different media can flow in opposite directions (or in the same direction) within the shell side and tube side to achieve heat exchange. In reverse heat exchange, the hot fluid enters from the top, while the cold fluid enters from the bottom. Heat is transferred from one fluid to the other through the inner tube wall. The shell-and-tube heat exchanger has a large heat transfer area, and due to the significant turbulence of the fluid flowing within the shell, it can achieve turbulent flow at relatively low velocities, resulting in high heat transfer efficiency. Of course, in other embodiments, the front heat exchanger 20 can also use other types of heat exchangers, as long as liquid-liquid heat exchange can be achieved.

[0062] like Figure 1 As shown, in one embodiment, the water inlet 21a of the first heat exchange channel 21 is connected to the water inlet pipe 11 through a first bypass port A, and the water outlet 21b of the first heat exchange channel 21 is connected to the water inlet pipe 11 through a second bypass port B. The first bypass port A is located upstream of the second bypass port B in the water inlet direction.

[0063] In this embodiment, by connecting the inlet end 21a and the outlet end of the first heat exchange channel 21 to the inlet pipe 11 via the first bypass port A and the second bypass port B respectively, the first heat exchange channel 21 and the pipe section of the inlet pipe 11 located between the first bypass port A and the second bypass port B (such as the second inlet pipe section 112) are arranged in parallel. Thus, in the water inlet direction, when the water in the inlet pipe 11 flows to the first bypass port A, a portion can be diverted into the first heat exchange channel 21 to participate in heat exchange. The heated water then flows back to the inlet pipe 11 via the second bypass port B and is then transported to the main heat exchanger 14. Furthermore, by arranging the first heat exchange channel 21 and a portion of the inlet pipe 11 in parallel, it is also beneficial to selectively control whether the water in the inlet pipe 11 is heat-exchanged by the pre-heat exchanger 20 before being transported to the main heat exchanger 14 by setting up the switching device 30. The inlet end 21a and outlet end 21b of the first heat exchange channel 21 can be directly connected to the inlet pipe 11, or the inlet end 21a and outlet end 21b of the first heat exchange channel 21 can be connected to the inlet pipe 11 through connecting pipes respectively.

[0064] For example Figures 1 to 6 As shown, in some embodiments, the water inlet pipe 11 includes a first water inlet pipe section 111, a second water inlet pipe section 112, and a third water inlet pipe section 113 connected sequentially along the water inlet direction. A first bypass port A is provided at the connection between the first water inlet pipe section 111 and the second water inlet pipe section 112, and a second bypass port B is provided at the connection between the second water inlet pipe section 112 and the third water inlet pipe section 113. The first heat exchange channel 21 is connected in parallel with the second water inlet pipe section 112 between the first bypass port A and the second bypass port B. The water heater 100 also includes a switching device 30, which is used to control the water in the water in the water inlet pipe 11 to be transported to the main heat exchanger 14 after heat exchange with the water in the outlet pipe 12 via the pre-heat exchanger 20 in the first state, and to control the water in the water in the water in the water inlet pipe 11 to be transported directly to the main heat exchanger 14 without participating in heat exchange in the second state.

[0065] In this embodiment, the first heat exchange channel 21 and the second inlet pipe section 112 are connected in parallel, and the switching device 30 switches the second inlet pipe section 112 and the first heat exchange channel 21 on and off, thereby controlling whether the water in the inlet pipe 11 is heat-exchanged by the preheater 20 before being delivered to the main heat exchanger 14. For example, when the switching device 30 is in the first state (e.g. Figure 2As shown), the first heat exchange channel 21 is open, and the second inlet pipe section 112 is closed. At this time, external cold water is sequentially transported to the main heat exchanger 14 via the first inlet pipe section 111, the first heat exchange channel 21, and the third inlet pipe section 113. The water in the first heat exchange channel 21 can exchange heat with the water in the second heat exchange channel 22, thereby increasing the inlet water temperature to the main heat exchanger 14 and reducing condensate generation. When the switching device 30 is in the second state (e.g., ... Figure 3 As shown, the first heat exchange channel 21 is blocked and the second water inlet pipe section 112 is open. At this time, external cold water is directly transported to the main heat exchanger 14 through the first water inlet pipe section 111, the second water inlet pipe section 112 and the third water inlet pipe section 113 without passing through the first heat exchange channel 21 for heat exchange.

[0066] There are multiple ways for the switching device 30 to achieve the above functions. The following are examples of several implementation methods of the switching device 30.

[0067] like Figures 1 to 3 As shown, in the first embodiment, the switching device 30 is configured as a three-way valve, the first water inlet pipe section 111 and the second water inlet pipe section 112 are connected through the three-way valve, the first bypass port A is provided in the three-way valve, and the three-way valve is used to control the first water inlet pipe section 111 to selectively connect to the first heat exchange channel 21 and / or the second water inlet pipe section 112.

[0068] In this embodiment, the three-way valve may include a valve body and a valve core disposed within the valve body. The valve body has a first port communicating with a first inlet pipe section 111, a second port communicating with a second inlet pipe section 112, and a first bypass port A for communicating with the inlet end 21a of the first heat exchange channel 21. The valve core is used to control the first port to selectively connect to the second port and / or the first bypass port A, thereby enabling the first inlet pipe section 111 to selectively connect to the first heat exchange channel 21 and / or the second inlet pipe section 112. For example, when the three-way valve is in a first state (e.g....), Figure 2 As shown), the first inlet pipe section 111 is separately connected to the first heat exchange channel 21. At this time, cold water can flow into the first heat exchange channel 21 through the first inlet pipe section 111 to exchange heat with the hot water in the second heat exchange channel 22 before flowing out to the third inlet pipe section 113. For example, when the three-way valve is in the second state (such as...), Figure 3As shown, the first inlet pipe section 111 is connected to the second inlet pipe section 112 separately. In this case, the water in the first inlet pipe section 111 is not transported through the first heat exchange channel 21, but is directly transported to the main heat exchanger 14 by the second inlet pipe section 112 and the third inlet pipe section 113. For example, when the three-way valve is in the third state, the first inlet pipe section 111 is connected to both the first heat exchange channel 21 and the second inlet pipe section 112. This allows a portion of the water in the first inlet pipe section 111 to flow into the first heat exchange channel 21 for heat exchange before being transported to the third inlet pipe section 113, while the other portion is directly transported to the third inlet pipe section 113 through the second inlet pipe section 112 without participating in the heat exchange of the preceding heat exchanger 20.

[0069] like Figure 4 As shown, in the second embodiment, the switching device 30 is configured as a three-way valve, the second water inlet pipe section 112 and the third water inlet pipe section 113 are connected through the three-way valve, the second bypass port B is provided at the three-way valve, and the three-way valve is used to control the third water inlet pipe section 113 to selectively connect to the first heat exchange channel 21 and / or the second water inlet pipe section 112.

[0070] In this embodiment, the three-way valve may include a valve body and a valve core disposed within the valve body. The valve body has a first port communicating with the second inlet pipe section 112, a second port communicating with the third inlet pipe section 113, and a second bypass port B for communicating with the outlet end 21b of the first heat exchange channel 21. The valve core is used to control the second port to selectively connect to the second bypass port B and / or the first port, thereby enabling the third inlet pipe section 113 to selectively connect to the first heat exchange channel 21 and / or the second inlet pipe section 112. For example, when the three-way valve is in the first state, the third inlet pipe section 113 is connected to the first heat exchange channel 21 alone. At this time, cold water can flow into the first heat exchange channel 21 through the first inlet pipe section 111 to exchange heat with the hot water in the second heat exchange channel 22 before flowing out to the third inlet pipe section 113. For example, when the three-way valve is in the second state, the third inlet pipe section 113 is connected to the second inlet pipe section 112 alone. At this time, the water in the first inlet pipe section 111 can be directly transported to the main heat exchanger 14 through the second inlet pipe section 112 and the third inlet pipe section 113. It is worth noting that in the second state, although the water in the first inlet pipe section 111 can enter the first heat exchange channel 21, the water in the first heat exchange channel 21 cannot continue to flow to the third inlet pipe section 113 because the outlet end 21b of the first heat exchange channel 21 is cut off from the third inlet pipe section 113. Therefore, the water after heat exchange cannot be transported to the main heat exchanger 14. For example, when the three-way valve is in the third state, the third inlet pipe section 113 is simultaneously connected to the first heat exchange channel 21 and the second inlet pipe section 112, so that the water that has undergone heat exchange in the first heat exchange channel 21 and the water that has not participated in heat exchange in the second inlet pipe section 112 can be combined in the third inlet pipe section 113 and transported to the main heat exchanger 14.

[0071] like Figure 5 and Figure 6 As shown, in some embodiments, the switching device 30 includes a first switching valve 31 and a second switching valve 32; the first switching valve 31 is disposed in the second inlet pipe section 112; the second switching valve 32 is disposed in the first heat exchange channel 21, or in the pipeline between the inlet end 21a of the first heat exchange channel 21 and the first bypass port A, or in the pipeline between the outlet end 21b of the first heat exchange channel 21 and the second bypass port B.

[0072] In this embodiment, two independent switching valves cooperate to achieve an effect similar to a single three-way valve. The first switching valve 31 controls the opening and closing of the second inlet pipe section 112. The second switching valve 32 controls the opening and closing of its corresponding pipe section. For example, when the second switching valve 32 is located in the first heat exchange channel 21, it controls the opening and closing of the first heat exchange channel 21. When the second switching valve 32 is located in the pipe between the inlet end 21a and the first bypass port A of the first heat exchange channel 21, it controls the opening and closing of the pipe between the inlet end 21a and the first bypass port A. When the second switching valve 32 is located in the pipe between the outlet end 21b and the second bypass port B of the first heat exchange channel 21, it controls the opening and closing of the pipe between the outlet end 21b and the second bypass port B.

[0073] like Figure 5 As shown, in the third embodiment, the switching device 30 includes a first switching valve 31 and a second switching valve 32. The first switching valve 31 is located in the second water inlet pipe section 112, and the second switching valve 32 is located in the pipeline between the water inlet end 21a of the first heat exchange channel 21 and the first bypass port A.

[0074] In this embodiment, the arrangement of the first switching valve 31 and the second switching valve 32 is the same as in the first embodiment (e.g., Figure 1 The effect of the three-way valve (as shown) is similar. For example, when the switching device 30 is in the first state, the first switch valve 31 is closed and the second switch valve 32 is open. At this time, cold water can flow into the first heat exchange channel 21 through the first inlet pipe section 111 to exchange heat with the hot water in the second heat exchange channel 22 before flowing out to the third inlet pipe section 113. When the switching device 30 is in the second state, the first switch valve 31 is open and the second switch valve 32 is closed. At this time, the water in the first inlet pipe section 111 does not pass through the first heat exchange channel 21 but is directly transported to the main heat exchanger 14 through the second inlet pipe section 112 and the third inlet pipe section 113. When the switching device 30 is in the third state, both the first switch valve 31 and the second switch valve 32 are open, so that part of the water in the first inlet pipe section 111 can flow into the first heat exchange channel 21 for heat exchange and then be transported to the third inlet pipe section 113, while the other part is directly transported to the third inlet pipe section 113 through the second inlet pipe section 112.

[0075] like Figure 6 As shown, in the fourth embodiment, the switching device 30 includes a first switching valve 31 and a second switching valve 32. The first switching valve 31 is located in the second inlet pipe section 112, and the second switching valve 32 is located in the pipeline between the outlet end 21b of the first heat exchange channel 21 and the second bypass port B.

[0076] In this embodiment, the arrangement of the first switching valve 31 and the second switching valve 32 is the same as in the second embodiment (e.g.) Figure 4 The effect of the three-way valve (as shown) is similar. For example, when the switching device 30 is in the first state, the first switch valve 31 is closed and the second switch valve 32 is open. At this time, cold water can flow into the first heat exchange channel 21 through the first inlet pipe section 111 to exchange heat with the hot water in the outlet pipe 12 before flowing out to the third inlet pipe section 113. When the switching device 30 is in the second state, the water in the first inlet pipe section 111 can be directly transported to the main heat exchanger 14 through the second inlet pipe section 112 and the third inlet pipe section 113. It is worth noting that in the second state, although the water in the first inlet pipe section 111 can enter the first heat exchange channel 21, the water in the first heat exchange channel 21 cannot continue to flow to the third inlet pipe section 113 because the pipe between the outlet end 21b of the first heat exchange channel 21 and the second bypass port B is cut off. Therefore, the water cannot be transported to the main heat exchanger 14 after heat exchange. When the switching device 30 is in the third state, both the first switching valve 31 and the second switching valve 32 are opened, so that part of the water in the first water inlet pipe section 111 can flow into the first heat exchange channel 21 for heat exchange and then be transported to the third water inlet pipe section 113, while the other part is directly transported to the third water inlet pipe section 113 through the second water inlet pipe section 112.

[0077] like Figure 7 As shown, in one embodiment, the inlet end 22a of the second heat exchange channel 22 is connected to the outlet pipe 12 through the third bypass port C, and the outlet end 22b of the second heat exchange channel 22 is connected to the outlet pipe 12 through the fourth bypass port D. The third bypass port C is located upstream of the fourth bypass port D in the water outlet direction.

[0078] In this embodiment, the inlet end 22a and outlet end 22b of the second heat exchange channel 22 are connected to the outlet pipe 12 through the third bypass port C and the fourth bypass port D, respectively, so that the second heat exchange channel 22 and the pipe section of the outlet pipe 12 located between the third bypass port C and the fourth bypass port D (such as the second outlet pipe section 122) are arranged in parallel. In this way, in the water outlet direction, when the hot water in the outlet pipe 12 flows to the third bypass port C, a portion can be diverted into the second heat exchange channel 22 to exchange heat with the cold water in the first heat exchange channel 21, thereby allowing the water in the inlet pipe 11 to be heated and then transported to the main heat exchanger 14 to reduce the generation of condensate; after heat exchange, the water in the second heat exchange channel 22 flows out through the fourth bypass port D to the outlet end of the outlet pipe 12. Furthermore, by connecting the second heat exchange channel 22 in parallel with a portion of the outlet pipe 12, it is also beneficial to selectively control whether the water in the outlet pipe 12 is heat-exchanged by the preheater 20 before being output by setting up the switching device 30. The inlet end 22a and the outlet end 22b of the second heat exchange channel 22 can be directly connected to the outlet pipe 12, or the inlet end 22a and the outlet end 22b of the second heat exchange channel 22 can be connected to the outlet pipe 12 respectively via connecting pipes.

[0079] like Figure 7 As shown, in one embodiment, the water outlet pipe 12 includes a first water outlet pipe section 121, a second water outlet pipe section 122, and a third water outlet pipe section 123 connected sequentially along the water outlet direction. The third bypass port C is provided at the connection between the first water outlet pipe section 121 and the second water outlet pipe section 122, and the fourth bypass port D is provided at the connection between the second water outlet pipe section 122 and the third water outlet pipe section 123. The second heat exchange channel 22 is connected in parallel with the second water outlet pipe section 122 between the third bypass port C and the fourth bypass port D. The water heater 100 also includes a switching device 30. The switching device 30 is used to control the water in the inlet pipe 11 to be transported to the main heat exchanger 14 after heat exchange with the water in the outlet pipe 12 via the pre-heat exchanger 20 in the first state, and to control the water in the outlet pipe 12 to be directly output without participating in heat exchange in the second state.

[0080] In this embodiment, the second heat exchange channel 22 and the second outlet pipe section 122 are connected in parallel, and the switching device 30 switches the second outlet pipe section 122 and the second heat exchange channel 22 on and off, thereby controlling whether the water in the outlet pipe 12 is heat-exchanged by the pre-heat exchanger 20 before being output. For example, when the switching device 30 is in the first state (e.g. Figure 8As shown), the second heat exchange channel 22 is open, and the second outlet pipe section 122 is closed. At this time, the hot water output from the main heat exchanger 14 is sequentially output through the first outlet pipe section 121, the second heat exchange channel 22, and the third outlet pipe section 123. The hot water in the second heat exchange channel 22 can exchange heat with the cold water in the first heat exchange channel 21, thereby increasing the temperature of the inlet water transported to the main heat exchanger 14 from the inlet pipe 11 and reducing condensate generation. When the switching device 30 is in the second state (e.g., ... Figure 9 As shown, the second heat exchange channel 22 is isolated and the second outlet pipe section 122 is open. At this time, the hot water output from the main heat exchanger 14 is directly output through the first outlet pipe section 121, the second outlet pipe section 122 and the third outlet pipe section 123 in sequence. The hot water in the outlet pipe 12 will not enter the second heat exchange channel 22 to participate in heat exchange, so that the water in the first heat exchange channel 21 will not be heated, and the water in the inlet pipe 11 will not participate in heat exchange and will be directly transported to the main heat exchanger 14.

[0081] There are multiple ways for the switching device 30 to achieve the above functions. The following are examples of several implementation methods of the switching device 30.

[0082] like Figures 7 to 9 As shown, in the fifth embodiment, the switching device 30 is configured as a three-way valve, the first outlet pipe section 121 and the second outlet pipe section 122 are connected through the three-way valve, the third bypass port C is provided at the three-way valve, and the three-way valve is used to control the first outlet pipe section 121 to selectively connect to the second heat exchange channel 22 and / or the second outlet pipe section 122.

[0083] In this embodiment, the three-way valve may include a valve body and a valve core disposed within the valve body. The valve body has a first port communicating with a first outlet pipe section 121, a second port communicating with a second outlet pipe section 122, and a third bypass port C for communicating with the inlet end 22a of the second heat exchange channel 22. The valve core is used to control the first port to selectively connect to the second port and / or the third bypass port C, thereby enabling the first outlet pipe section 121 to selectively connect to the second heat exchange channel 22 and / or the second outlet pipe section 122. For example, when the three-way valve is in the first state (e.g.... Figure 8 As shown), the first outlet pipe section 121 is separately connected to the second heat exchange channel 22. At this time, the hot water output from the main heat exchanger 14 can flow through the first outlet pipe section 121 into the second heat exchange channel 22 to exchange heat with the cold water in the first heat exchange channel 21 before flowing out to the third outlet pipe section 123. For example, when the three-way valve is in the second state (e.g., ... Figure 9As shown, the first outlet pipe section 121 is connected to the second outlet pipe section 122 independently. In this case, the water in the first outlet pipe section 121 is directly output through the second outlet pipe section 122 and the third outlet pipe section 123 without passing through the second heat exchange channel 22. For example, when the three-way valve is in the third state, the first outlet pipe section 121 is connected to both the second heat exchange channel 22 and the second outlet pipe section 122. This allows a portion of the water in the first outlet pipe section 121 to flow into the second heat exchange channel 22 for heat exchange before being transported to the third outlet pipe section 123, while the other portion is directly transported to the third outlet pipe section 123 through the second outlet pipe section 122.

[0084] like Figure 10 As shown, in the sixth embodiment, the switching device 30 is configured as a three-way valve, the second outlet pipe section 122 and the third outlet pipe section 123 are connected through the three-way valve, the fourth bypass port D is provided at the three-way valve, and the three-way valve is used to control the third outlet pipe section 123 to selectively connect to the second heat exchange channel 22 and / or the second outlet pipe section 122.

[0085] In this embodiment, the three-way valve may include a valve body and a valve core disposed within the valve body. The valve body has a first port communicating with the second outlet pipe section 122, a second port communicating with the third outlet pipe section 123, and a fourth bypass port D for communicating with the outlet end 22b of the second heat exchange channel 22. The valve core is used to control the second port to selectively communicate with the fourth bypass port D and / or the first port, thereby enabling the third outlet pipe section 123 to selectively communicate with the second heat exchange channel 22 and / or the second outlet pipe section 122. For example, when the three-way valve is in the first state, the third outlet pipe section 123 is connected to the second heat exchange channel 22 alone. At this time, the hot water output from the main heat exchanger 14 can flow into the second heat exchange channel 22 via the first outlet pipe section 121 to exchange heat with the cold water in the first heat exchange channel 21 before flowing out to the third outlet pipe section 123. For example, when the three-way valve is in the second state, the third outlet pipe section 123 is connected to the second outlet pipe section 122 alone. At this time, the hot water in the first outlet pipe section 121 can be directly output through the second outlet pipe section 122 and the third outlet pipe section 123. It is worth noting that in the second state, although a certain amount of hot water will accumulate in the second heat exchange channel 22, the water in the second heat exchange channel 22 cannot flow continuously because the outlet end 22b of the second heat exchange channel 22 is cut off. Therefore, the temperature of the hot water in the second heat exchange channel 22 will decrease after one heat exchange, and it will not have a good heat exchange effect with the cold water in the first heat exchange channel 21. Thus, the water temperature rise in the inlet pipe 11 is not significant. As another example, when the three-way valve is in the third state, the third outlet pipe section 123 is connected to both the second heat exchange channel 22 and the second outlet pipe section 122, so that the water in the second heat exchange channel 22 after heat exchange and the water in the second outlet pipe section 122 can be combined in the third outlet pipe section 123 before being output.

[0086] like Figure 11 and Figure 12 As shown, in some embodiments, the switching device 30 includes a first switching valve 31 and a second switching valve 32; the first switching valve 31 is disposed in the second outlet pipe section 122; the second switching valve 32 is disposed in the second heat exchange channel 22, or in the pipeline between the inlet end 22a of the second heat exchange channel 22 and the third bypass port C, or in the pipeline between the outlet end 22b of the second heat exchange channel 22 and the fourth bypass port D.

[0087] In this embodiment, two independent switching valves cooperate to achieve an effect similar to a single three-way valve. The first switching valve 31 controls the on / off state of the second outlet pipe section 122. The second switching valve 32 controls the on / off state of its corresponding pipe section. For example, when the second switching valve 32 is located in the second heat exchange channel 22, it controls the on / off state of the second heat exchange channel 22. When the second switching valve 32 is located in the pipe between the inlet end 22a and the third bypass port C of the second heat exchange channel 22, it controls the on / off state of the pipe between the inlet end 22a and the third bypass port C. When the second switching valve 32 is located in the pipe between the outlet end 22b and the fourth bypass port D of the second heat exchange channel 22, it controls the on / off state of the pipe between the outlet end 22b and the fourth bypass port D.

[0088] like Figure 11 As shown, in the seventh embodiment, the switching device 30 includes a first switching valve 31 and a second switching valve 32; the first switching valve 31 is located in the second outlet pipe section 122, and the second switching valve 32 is located in the pipeline between the inlet end 22a of the second heat exchange channel 22 and the third bypass port C.

[0089] In this embodiment, the arrangement of the first switching valve 31 and the second switching valve 32 is the same as in the fifth embodiment (e.g.) Figure 7The effect of the three-way valve (as shown) is similar. For example, when the switching device 30 is in the first state, the first switch valve 31 is closed and the second switch valve 32 is open. At this time, the hot water output from the main heat exchanger 14 can flow into the second heat exchange channel 22 through the first outlet pipe section 121 to exchange heat with the cold water in the first heat exchange channel 21 before flowing out to the third outlet pipe section 123. When the switching device 30 is in the second state, the first switch valve 31 is open and the second switch valve 32 is closed. At this time, the water in the first outlet pipe section 121 does not pass through the second heat exchange channel 22 but is directly output through the second outlet pipe section 122 and the third outlet pipe section 123. When the switching device 30 is in the third state, both the first switch valve 31 and the second switch valve 32 are open, so that part of the water in the first outlet pipe section 121 can flow into the second heat exchange channel 22 for heat exchange and then be transported to the third outlet pipe section 123, while the other part is directly transported to the third outlet pipe section 123 through the second outlet pipe section 122.

[0090] like Figure 12 As shown, in the eighth embodiment, the switching device 30 includes a first switching valve 31 and a second switching valve 32; the first switching valve 31 is located on the second outlet pipe section 122, and the second switching valve 32 is located on the pipeline between the outlet end 22b of the second heat exchange channel 22 and the fourth bypass port D.

[0091] In this embodiment, the arrangement of the first switching valve 31 and the second switching valve 32 is the same as in the sixth embodiment (e.g.) Figure 10 The effect of the three-way valve (as shown) is similar. For example, when the switching device 30 is in the first state, the first switching valve 31 is closed and the second switching valve 32 is open. At this time, the hot water output from the main heat exchanger 14 can flow into the second heat exchange channel 22 through the first outlet pipe section 121 to exchange heat with the cold water in the first heat exchange channel 21 before flowing out to the third outlet pipe section 123. For example, when the switching device 30 is in the second state, the first switching valve 31 is open and the second switching valve 32 is closed. At this time, the hot water in the first outlet pipe section 121 can be directly output through the second outlet pipe section 122 and the third outlet pipe section 123. It is worth noting that in the second state, although some hot water accumulates in the second heat exchange channel 22, the water in the second heat exchange channel 22 cannot flow continuously because the outlet end 22b of the second heat exchange channel 22 is cut off. Therefore, the temperature of the hot water in the second heat exchange channel 22 will decrease after one heat exchange, and it will not have a good heat exchange effect with the cold water in the first heat exchange channel 21. As a result, the water temperature rise in the inlet pipe 11 is not significant. For example, when the switching device 30 is in the third state, the third outlet pipe section 123 is connected to both the second heat exchange channel 22 and the second outlet pipe section 122, so that the water that has undergone heat exchange in the second heat exchange channel 22 and the water in the second outlet pipe section 122 can be combined and output in the third outlet pipe section 123.

[0092] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A water heater, characterized in that, include: The water heater body includes an inlet pipe, an outlet pipe, a burner, and a main heat exchanger. The inlet end of the main heat exchanger is connected to the inlet pipe, and the outlet end of the main heat exchanger is connected to the outlet pipe. The burner is used to generate flue gas for heat exchange with the water in the main heat exchanger. The front heat exchanger has a first heat exchange channel and a second heat exchange channel. The first heat exchange channel is connected to the inlet water pipe, and the second heat exchange channel is connected to the outlet water pipe. The front heat exchanger is used to exchange heat between the water in the inlet water pipe and the water in the outlet water pipe.

2. The water heater as described in claim 1, characterized in that, The inlet pipe, the outlet pipe, and the pre-exchange heat exchanger are connected to form a heat exchange pipe system. The water heater also includes a switching device installed in the heat exchange pipe system. The switching device is used to control the water in the inlet pipe to be transported to the main heat exchanger after heat exchange with the water in the outlet pipe via the pre-exchange heat exchanger in a first state. The switching device is also used to control the water in the inlet pipe to be transported directly to the main heat exchanger without participating in heat exchange or to control the water in the outlet pipe to be output directly without participating in heat exchange in a second state.

3. The water heater as described in claim 2, characterized in that, The water heater also includes an inlet water temperature sensor that is communicatively connected to the switching device. The inlet water temperature sensor is located in the inlet pipe and upstream of the first heat exchange channel in the water inlet direction. The switching device is used to switch between the first state and the second state according to the inlet water temperature. And / or, the water heater further includes an outlet water temperature sensor that is communicatively connected to the switching device. The outlet water temperature sensor is located in the outlet pipe and downstream of the second heat exchange channel in the outlet direction. The switching device is used to switch between the first state and the second state according to the outlet water temperature.

4. The water heater as described in claim 1, characterized in that, The front heat exchanger is configured as a plate heat exchanger or a shell-and-tube heat exchanger.

5. The water heater as described in any one of claims 1 to 4, characterized in that, The inlet end of the first heat exchange channel is connected to the inlet pipeline through a first bypass port, and the outlet end of the first heat exchange channel is connected to the inlet pipeline through a second bypass port. The first bypass port is located upstream of the second bypass port in the water inlet direction.

6. The water heater as described in claim 5, characterized in that, The water inlet pipeline includes a first water inlet pipe section, a second water inlet pipe section, and a third water inlet pipe section connected sequentially along the water inlet direction. A first bypass port is provided at the connection between the first water inlet pipe section and the second water inlet pipe section, and a second bypass port is provided at the connection between the second water inlet pipe section and the third water inlet pipe section. The first heat exchange channel is connected in parallel with the second water inlet pipe section between the first bypass port and the second bypass port. The water heater also includes a switching device, which is used to control the water in the inlet pipe to be transported to the main heat exchanger after exchanging heat with the water in the outlet pipe via the pre-heat exchanger in the first state, and to control the water in the inlet pipe to be transported directly to the main heat exchanger without participating in heat exchange in the second state.

7. The water heater as described in claim 6, characterized in that, The switching device is configured as a three-way valve, the first water inlet pipe section and the second water inlet pipe section are connected through the three-way valve, the first bypass port is provided at the three-way valve, and the three-way valve is used to control the first water inlet pipe section to selectively connect to the first heat exchange channel and / or the second water inlet pipe section. Alternatively, the switching device is configured as a three-way valve, the second inlet pipe section and the third inlet pipe section are connected through the three-way valve, the second bypass port is provided at the three-way valve, and the three-way valve is used to control the third inlet pipe section to selectively connect to the first heat exchange channel and / or the second inlet pipe section; Alternatively, the switching device includes a first switching valve and a second switching valve; the first switching valve is located in the second inlet pipe section; the second switching valve is located in the first heat exchange channel, or in the pipeline between the inlet end of the first heat exchange channel and the first bypass port, or in the pipeline between the outlet end of the first heat exchange channel and the second bypass port.

8. The water heater as described in any one of claims 1 to 4, characterized in that, The inlet of the second heat exchange channel is connected to the outlet pipe through a third bypass port, and the outlet of the second heat exchange channel is connected to the outlet pipe through a fourth bypass port. The third bypass port is located upstream of the fourth bypass port in the outlet direction.

9. The water heater as described in claim 8, characterized in that, The water outlet pipeline includes a first water outlet pipe section, a second water outlet pipe section, and a third water outlet pipe section connected sequentially along the water outlet direction. The third bypass port is provided at the connection between the first water outlet pipe section and the second water outlet pipe section, and the fourth bypass port is provided at the connection between the second water outlet pipe section and the third water outlet pipe section. The second heat exchange channel is connected in parallel with the second water outlet pipe section between the third bypass port and the fourth bypass port. The water heater also includes a switching device, which is used to control the water in the inlet pipe to be transported to the main heat exchanger after exchanging heat with the water in the outlet pipe via the pre-heat exchanger in the first state, and to control the water in the outlet pipe to be directly output without participating in heat exchange in the second state.

10. The water heater as described in claim 9, characterized in that, The switching device is configured as a three-way valve, the first outlet pipe section and the second outlet pipe section are connected through the three-way valve, the third bypass port is provided at the three-way valve, and the three-way valve is used to control the first outlet pipe section to selectively connect to the second heat exchange channel and / or the second outlet pipe section. Alternatively, the switching device is configured as a three-way valve, the second outlet pipe section and the third outlet pipe section are connected through the three-way valve, the fourth bypass port is provided at the three-way valve, and the three-way valve is used to control the third outlet pipe section to selectively connect to the second heat exchange channel and / or the second outlet pipe section; Alternatively, the switching device includes a first switching valve and a second switching valve; the first switching valve is located in the second outlet pipe section; the second switching valve is located in the second heat exchange channel, or in the pipeline between the inlet end of the second heat exchange channel and the third bypass port, or in the pipeline between the outlet end of the second heat exchange channel and the fourth bypass port.

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