Instant water heater adopting multi-heating-pipe combined heating and control method

Abstract

The invention relates to the technical field of water heaters, and discloses a multi-heating-pipe combined heating instant water heater and a control method.The multi-heating-pipe combined heating instant water heater comprises a shell, a water inlet pipeline, a water outlet pipeline and an electric heating element are arranged in the shell, and the electric heating element is provided with a water inlet and a water outlet; the water inlet pipeline is communicated with the water inlet, the water outlet pipeline is communicated with the water outlet, the water inlet pipeline is connected with an electric water pump, the electric heating element comprises a plurality of heating pipes which are connected in series, the heating pipes are used for heating water flowing through the interiors of the heating pipes, and a control element is arranged on the shell. The water outlet temperature is controlled by independently controlling power-on and power-off of the multiple heating pipes, the control structure is simple, the production cost is low, and control is accurate and reliable; the heating work of the heating pipe is controlled according to the temperature difference of the inlet and outlet water temperature, the outlet water temperature is not prone to being affected by seasons and the inlet water temperature, the accuracy of the outlet water temperature is further improved, and the use experience is good.

Description

Technical Field

[0001] The present invention relates to the technical field of water heaters, and in particular to an instantaneous water heater with multiple heating tubes for combined heating and a control method thereof. Background Art

[0002] Instant water heaters, also known as instant or quick-heating water heaters, are characterized by a continuous supply of hot water for a short period of time, with cold water flowing out and hot water being supplied by simply opening the outlet valve. When hot water is not needed, heating can be stopped by closing the outlet valve and shutting off the water supply. Currently, most instant water heaters are electric or gas-fired. Electric instant water heaters utilize a high-power electric heater to rapidly heat cold water flowing through the heating zone, bringing it to the desired operating temperature. This achieves the goal of cold water in and hot water out. Because they eliminate the water storage device found in storage water heaters (for example, the dynamic water storage device in household electric water heaters typically holds tens of liters), they are compact and easy to install.

[0003] Some existing instant water heaters control the outlet water temperature by controlling the heating power of the electric heating element. For example, the user adjusts the temperature to the desired level by turning the temperature adjustment knob / button. At this time, the electric heating element heats with the power preset for that level. This type of method will have the following problems: 1. The electric heating element requires specific control components for control, and the control accuracy is poor, which makes it difficult for the electric heating element to operate stably at a fixed power, thereby affecting the accuracy of the outlet water temperature. If higher-precision control components are used, the production and maintenance costs will be higher; 2. The water temperature of the water outlet at the same level is different in different seasons. For example, at the same temperature level (i.e., the same operating power of the electric heating element), the outlet water temperature in winter is lower than that in summer, which makes it inconvenient for users to adjust the outlet water temperature to the desired temperature, causing inconvenience and poor user experience. Summary of the Invention

[0004] In order to solve at least one aspect of the above problems, the present invention provides an instant water heater with multi-heating tube combined heating, comprising: a shell, a water inlet pipe, a water outlet pipe and an electric heating element are arranged in the shell, the electric heating element is provided with a water inlet and a water outlet, the water inlet pipe is connected to the water inlet, the water outlet pipe is connected to the water outlet, an electric water pump is connected to the water inlet pipe, the electric heating element includes a plurality of heating tubes connected in series, the heating tubes are used to heat the water flowing through the interior thereof, a control element is provided on the shell, and the control element The number of control elements is the same as that of the heating tubes and they correspond one to one. The control elements are used to control the power on / off of the corresponding heating tubes. A first temperature sensor is provided on the shell, and the first temperature sensor is used to detect the water temperature in the water inlet pipe. The present invention controls the outlet water temperature by individually controlling the power on and off of multiple heating tubes. The control structure is simple, the production cost is low, and the control is accurate and reliable. The heating work of the heating tube is controlled according to the temperature difference between the inlet and outlet water temperatures. The outlet water temperature is not easily affected by the season and the incoming water temperature, which further improves the accuracy of the outlet water temperature and provides a good user experience.

[0005] Optionally, the electric heating element is a thick film heating body, and the heating tube includes a first heating tube, a second heating tube and a third heating tube connected in series, and the rated power of the first heating tube, the second heating tube and the third heating tube after being energized is different.

[0006] Optionally, the rated power of the first heating tube after being energized is a first power, the rated power of the second heating tube after being energized is a second power, and the rated power of the third heating tube after being energized is a third power. The values of the first power, the second power and the third power are an arithmetically increasing series, and the sum of the first power and the second power is greater than the third power.

[0007] Optionally, a second temperature sensor is provided on the shell, and the second temperature sensor is used to detect the water temperature in the water outlet pipe. A circuit control board is provided on the shell, and the heating tube, the control element, the first temperature sensor, the second temperature sensor and the electric water pump are all electrically connected to the circuit control board.

[0008] Optionally, a servo valve is connected to the water inlet pipeline, the electric water pump is a speed-adjustable DC motor water pump, and the control element is a relay.

[0009] The present invention also provides a control method for an instant water heater with a multi-heating tube combination heating, which includes the following steps: step S001, inputting the outlet water temperature, and the user adjusts the outlet water temperature gear to the required outlet water temperature gear through the knob or button on the shell; step S002, calculating the temperature difference required for heating, detecting the water temperature in the water inlet pipe through the first temperature sensor, and calculating the temperature difference between the user-input outlet water temperature and the water temperature in the water inlet pipe; step S003, calculating the heating power required by the electric heating element, and calculating the heating power required by the electric heating element according to the temperature difference Δ required for heating and the preset water flow rate of the outlet pipe; step S004, calculating the heating tubes that need to be energized, and the heating power of the electric heating element is the sum of the powers of each heating tube in the energized state, and the heating power of the electric heating element is calculated according to the required heating power of the electric heating element. The heating power and the heating power of each heating pipe are used to calculate the heating pipe that needs to be energized; in step S005, the servo valve adjusts the corresponding flow, and the actual water outlet flow of the water outlet pipe is adjusted by the servo valve connected to the water inlet pipe, so that the actual water outlet flow matches the preset water outlet flow; in step S006, hot water is discharged, and the electric water pump is controlled to start and the servo valve is controlled to open by the switch on the shell, so that water is discharged from the water outlet pipe. When the actual water outlet flow matches the preset water outlet flow, the heating pipe that needs to be energized is controlled by the control element to be energized and heated, so that the sum of the power of each heating pipe matches the heating power required by the electric heating element, so that the outlet water temperature of the water outlet pipe approaches the outlet water temperature input by the user; in step S007, the water outlet is turned off, and the electric water pump is controlled to stop, the servo valve is controlled to close, and the power of each heating pipe is controlled to be cut off by the switch on the shell.

[0010] Optionally, the electric heating element is a thick film heating body, and the heating tube includes a first heating tube, a second heating tube and a third heating tube connected in series, and the rated power of the first heating tube, the second heating tube and the third heating tube after being energized is different.

[0011] Optionally, the rated power of the first heating tube after being energized is a first power, the rated power of the second heating tube after being energized is a second power, and the rated power of the third heating tube after being energized is a third power. The values of the first power, the second power and the third power are an arithmetically increasing series, and the sum of the first power and the second power is greater than the third power.

[0012] Optionally, a second temperature sensor is provided on the shell, and the second temperature sensor is used to detect the water temperature in the water outlet pipe. The temperature information used by the second temperature sensor can be transmitted to the servo valve, and the water temperature in the water outlet pipe will be collected by the second temperature sensor, and the collected temperature is compared with the water outlet temperature input by the user. When the collected temperature is higher than the water outlet temperature input by the user, the servo valve increases the opening to increase the flow rate; when the collected temperature is lower than the water outlet temperature input by the user, the servo valve decreases the opening to reduce the flow rate, so that the final water outlet temperature of the water outlet pipe matches the water outlet temperature input by the user; a circuit control board is provided on the shell, and the heating tube, the control element, the first temperature sensor, the second temperature sensor and the electric water pump are all electrically connected to the circuit control board. Connection, in the step S002, the temperature difference required for heating is calculated by the program on the circuit control board, and in the step S003, the heating power required for the electric heating element is calculated by the program on the circuit control board; in the step S004, the heating tube that needs to be powered on for heating is calculated by the program on the circuit control board; in the step S006, when the second temperature sensor detects that the water temperature in the water outlet pipe is lower than the user-input water outlet temperature, the corresponding heating tube is controlled to be powered on for heating; when the second temperature sensor detects that the water temperature in the water outlet pipe reaches the user-input water outlet temperature, the heating tube is maintained in the powered-on heating state, and at the same time, the electric water pump speed and the opening of the servo valve are maintained, so that the actual water outlet temperature is maintained at the user-input water outlet temperature.

[0013] Optionally, the electric water pump is a speed-adjustable DC motor water pump, and the control element is a relay.

[0014] Compared with the prior art, the instant water heater with multi-heating tube combined heating in the present invention controls the outlet water temperature by individually controlling the power on and off of multiple heating tubes, with a simple control structure, low production cost, accurate and reliable control; the heating work of the heating tube is controlled according to the temperature difference between the inlet and outlet water temperatures, and the outlet water temperature is not easily affected by the season and the incoming water temperature, further improving the accuracy of the outlet water temperature and providing a good user experience; through heating tubes of different powers, the heating power of the electric heating element can be changed by energizing different heating tubes; the heating power of the electric heating element can be changed by heating with different single heating tubes, heating with two heating tubes in combination, or heating with three heating tubes at the same time, and the total heating power of the electric heating element can be adjusted more flexibly; the values of the first power, the second power and the third power are an arithmetically increasing series, and the sum of the first power and the second power is greater than the third power. The value-taking method of the present control method can make the heating power value distribution of the electric heating element more uniform under different heating states, that is, the difference between two adjacent powers arranged from small to large has a small fluctuation, so as to meet the heating requirements under each input and outlet water temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A perspective view of an instant water heater with multiple heating tubes for combined heating according to the present invention;

[0016] Figure 2 This is a schematic diagram of the internal structure of the instant water heater with multiple heating tubes combined heating according to the present invention;

[0017] Figure 3 This is a schematic structural diagram of an instant water heater with multiple heating tubes for combined heating according to the present invention;

[0018] Figure 4 A three-dimensional diagram of the heating tubes of the instant water heater with multiple heating tubes combined heating according to the present invention;

[0019] Figure 5 This is a schematic diagram of the structure of the heating tubes of the instant water heater with multiple heating tubes combined heating according to the present invention;

[0020] Figure 6 A flowchart of a method for heating an instant water heater with multiple heating tubes according to the present invention;

[0021] Figure 7 This is a structural diagram of embodiment 2 of the present invention;

[0022] The corresponding component names of the various figure marks in the figure are: 1 is the shell, 101 is the knob, 10 is the water inlet, 11 is the water outlet, 12 is the switch, 2 is the water inlet pipe, 3 is the water outlet pipe, 40 is the electric heating element, 4 is the heating tube, 41 is the first heating tube, 42 is the second heating tube, 43 is the third heating tube, 6 is the electric water pump, 71 is the second temperature sensor, 72 is the second sensor, 73 is the third temperature sensor, 81 is the circuit control board, 82 is the servo valve, 91 is the inlet, Δ is the temperature difference, A is the first power, B is the second power, and C is the third power. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0024] In the description of the present invention, it should be understood that the terms "upper" and "lower" and the like indicate positions or location relationships based on the positions or location relationships during normal use of the product.

[0025] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0026] Example 1:

[0027] See Figure 1-Figure 5, Embodiment 1 of the present invention provides an instantaneous water heater with multi-heating tube combined heating, comprising: a shell 1, a water inlet pipe 2, a water outlet pipe 3 and an electric heating element 40 are arranged in the shell 1, the electric heating element 40 is provided with a water inlet 10 and a water outlet 11, the water inlet pipe 2 is connected to the water inlet 10, the water outlet pipe 3 is connected to the water outlet 11, the water inlet pipe 2 is connected to an electric water pump 6, the electric heating element 40 includes a plurality of heating tubes 4 connected in series, and the series connection means that the plurality of heating tubes 4 are connected end to end, and the water flows through the plurality of heating tubes 4 in sequence for heating; it should be noted that the technical solution of the plurality of heating tubes 4 connected in series also includes a whole integrated large heating tube formed by a plurality of heating tubes (heating sections) of different powers in series, and this technical solution also falls within the scope of protection of the present invention; the heating tube 4 is used to heat the water flowing through itself For heating, a control element is provided on the shell 1. The number of control elements is the same as that of the heating tubes 4 and they correspond one to one. One control element controls the power on and off of one heating tube 4. The control accuracy requirement of the control element that controls the power on and off is much lower than that of the components that control temperature change. Therefore, the production cost of the structure is low, and the control is more stable and reliable. The control element is used to control the power on / off of the corresponding heating tube 4. A first temperature sensor 71 is provided on the shell 1. The first temperature sensor 71 is used to detect the water temperature in the water inlet pipe 2. The present invention controls the outlet water temperature by individually controlling the power on and off of multiple heating tubes. The control structure is simple, the production cost is low, and the control is accurate and reliable. The heating work of the heating tube is controlled according to the temperature difference between the inlet and outlet water temperatures. The outlet water temperature is not easily affected by the season and the incoming water temperature, which further improves the accuracy of the outlet water temperature and provides a good user experience.

[0028] See Figure 2-Figure 5The electric heating element 40 is a thick film heating body, which has the advantages of high heating efficiency, small size, fast heating speed and long service life; the heating tube 4 includes a first heating tube 41, a second heating tube 42 and a third heating tube 43 connected in series, and the rated powers of the first heating tube 41, the second heating tube 42 and the third heating tube 43 after being energized are different. By energizing heating tubes of different powers, the heating power of the electric heating element 40 can be changed by energizing different heating tubes; for example, the heating power of the electric heating element 40 can be changed by heating with different single heating tubes, heating with a combination of two heating tubes, or heating with three heating tubes at the same time, and the total heating power of the electric heating element 40 can be adjusted more flexibly; the rated power of the first heating tube 41 after being energized is the first power A, the rated power of the second heating tube 42 after being energized is the second power B, and the rated power of the third heating tube 43 after being energized is the third power C, and the values of the first power A, the second power B and the third power C are an arithmetically increasing series, and the first The sum of power A and the second power B is greater than the third power C. The electric heating element 40 has different total heating powers under different working conditions: each heating tube is heated separately, any two are heated in combination, and three are heated simultaneously. The above-mentioned value-taking method can make the heating power value distribution of the electric heating element 40 in different heating states more uniform, that is, the difference between two adjacent powers arranged from small to large fluctuates less, so as to meet the heating requirements at each input and outlet water temperature. The flow rate in the pipeline is fine-tuned by adjusting the speed of the electric water pump 6 to make the output water temperature more accurate. It should be noted that when the heating power is constant, the greater the output flow rate, the lower the outlet water temperature; conversely, the smaller the output flow rate, the higher the outlet water temperature; therefore, the purpose of adjusting the outlet water temperature can be achieved by fine-tuning the flow rate in the pipeline, but the flow rate in the pipeline cannot be adjusted over a large range, because if the water outlet is small, it will affect the use; limited by the maximum speed of the water pump, it is also impossible to output too high a flow rate, so a variety of heating powers are required to match the outlet water temperature gear.

[0029] Optionally, see Figure 3 and Figure 4 The first heating tube 41, the second heating tube 42 and the third heating tube 43 are distributed vertically from bottom to top. A spiral heat exchange channel 91 is formed on the inner side of the heating tube 4, which makes the heat exchange more sufficient and the water temperature rises rapidly; the lower part of the spiral heat exchange channel 91 is provided with an inlet 92 connected to the water inlet 10, and the upper part of the spiral heat exchange channel 91 is provided with an outlet 93, and the outlet 93 is connected to the water outlet 11 with a water outlet channel 94; when in use, water enters from the water inlet 10, flows into the spiral heat exchange channel 91 through the inlet 92, flows upward along the spiral heat exchange channel 91 to the outlet 93, and then flows through the outlet 93, the outlet channel 94 and the water outlet 11 in sequence for discharge.

[0030] For further information, see Figure 3 and Figure 4A third temperature sensor 73 is provided on the upper part of the water outlet channel 94, and the third temperature sensor 73 is electrically connected to a temperature control switch. When the heating of the heating tube 4 is abnormal, resulting in the water temperature being too high (exceeding the maximum safe temperature preset by the third temperature sensor 73), the third temperature sensor 73 transmits the temperature signal to the temperature control switch, which controls the entire water heater to cut off the power through the temperature control switch to prevent the water temperature from further rising and scalding the human body, making it safer to use; the third temperature sensor 73 is provided on the upper part of the water outlet channel 94. Since the water in the upper part of the water outlet channel 94 has completed heat exchange, the water temperature here can reach or approach the maximum value, so that the third temperature sensor 73 can quickly obtain the water temperature information that is too high when the heating is abnormal, and then complete the work of quickly cutting off the power; in this embodiment, the third temperature sensor 73 is a patch temperature sensor with a small size and is easy to be arranged in a small space. The third temperature sensor 73 can also be of other suitable types.

[0031] See Figure 2 and Figure 5 A second temperature sensor 72 is provided on the housing 1. The second temperature sensor 72 is used to detect the water temperature in the water outlet pipe 3. A circuit control board 81 is provided on the housing 1. The heating tube 4, the control element, the first temperature sensor 71, the second temperature sensor 72 and the electric water pump 6 are all electrically connected to the circuit control board 81. The corresponding components are controlled by the program on the circuit control board 81, and the control is more intelligent and convenient; a servo valve 82 is connected to the water inlet pipe 2, and the servo valve 82 and the electric water pump 6 are linked to control the book flow rate. The servo valve 82 has its own feedback control system to further improve the flow rate adjustment accuracy; so that when the speed of the electric water pump 6 remains unchanged Under such circumstances, the flow rate can be adjusted by adjusting the opening of the servo valve 82 separately; the electric water pump 6 is a DC motor water pump with adjustable speed, and the control element is a relay, which has a simple structure and low production cost; the water output is controlled by the cooperation of the servo valve and the DC motor water pump. Compared with the structure of controlling the water temperature by thyristor, it is not easily disturbed by the magnetic field and electromagnetic radiation, and has stable operation, low noise and good user experience; the existing thyristor is easily disturbed by the magnetic field and electromagnetic radiation and easily generates electromagnetic noise; the first temperature sensor 71 and the second temperature sensor 72 can use probe-type temperature sensors. The metal probe has fast thermal conductivity, can quickly reflect temperature changes, and power off is more timely.

[0032] See Figures 1-6The present invention also provides a control method for an instantaneous water heater with multiple heating tubes for combined heating. The instantaneous water heater with multiple heating tubes for combined heating comprises the following steps: Step S001: inputting the outlet water temperature. The user adjusts the outlet water temperature level to the desired outlet water temperature level through a knob or button on the housing 1. In this embodiment, the knob 101 is used for adjustment, and the housing is marked with a corresponding temperature level scale; Step S002: calculating the temperature difference required for heating. The first temperature sensor 71 detects the water temperature in the water inlet pipe 2, and calculates the temperature difference Δ between the outlet water temperature input by the user and the water temperature in the water inlet pipe 2. ; Step S003, calculate the heating power required by the electric heating element 40, calculate the heating power required by the electric heating element 40 according to the temperature difference Δ required for heating and the preset water flow rate of the water outlet pipe 3, the preset water flow rate is a factory preset, and the industry generally takes a value of about 7L / min to meet the needs of general household use. In terms of usage experience: the water flow rate only needs to meet the normal use of the user, and a certain fluctuation is allowed, while the water outlet temperature requires a higher accuracy; Step S004, calculate the heating tube that needs to be energized, and the heating power of the electric heating element 40 is in the energized state The sum of the powers of the heating tubes 4 is calculated according to the heating power required by the electric heating element 40 and the heating power of each heating tube, and the specific heating tube(s) that need to be powered on for heating are calculated; Step S005, the servo valve adjusts the corresponding flow rate, and the actual water flow rate of the water outlet pipe 3 is adjusted by the servo valve 82 connected to the water inlet pipe 2, so that the actual water flow rate matches the preset water flow rate; Step S006, hot water is discharged, and the switch 12 on the housing 1 controls the electric water pump 6 to be powered on and the servo valve 82 to be opened, so that the water outlet pipe 3 discharges water, and the actual water flow rate matches the preset water flow rate. When the water outlet flow rate is set, the heating tubes that need to be energized are controlled by the control element to be energized for heating, so that the sum of the powers of each heating tube matches the heating power required by the electric heating element 40, so that the outlet water temperature of the water outlet pipe 3 approaches the outlet water temperature input by the user; the water heater first discharges water, and when the actual water outlet flow rate matches the preset water outlet flow rate, the electric heating element 40 is energized for heating to prevent dry burning or the electric heating element 40 being burned out due to excessive temperature; step S007, turn off the water outlet, control the electric water pump 6 to stop, control the servo valve 82 to close, and control the power off of each heating tube through the switch 12 on the shell 1.

[0033] In step S003, the heating power required by the electric heating element 40 is calculated based on the temperature difference Δ required for heating and the preset water flow rate of the water outlet pipe 3. The specific calculation method is: according to the calculation formula between heating power, flow rate and temperature difference:

[0034] G = 3.6*Q / (cΔ);

[0035] In the formula: G-----preset water flow rate, unit is t / h;

[0036] Q-----required heating power, in kW;

[0037] c-----specific heat capacity of water, in kJ / kg·℃, generally taken as 4.1868;

[0038] Δ-----The temperature difference required for heating, that is, the temperature difference between the input water temperature and the output water temperature, in °C;

[0039] In addition, the flow unit conversion formula is 1t / h = 16.67L / min.

[0040] In this embodiment, taking the electric heating element with a maximum heating power of 10.5kW as an example, the following setting parameters are provided: the first power A is set to 2.5kW, the second power B is set to 3.5kW, and the third power is set to 4.5kW. The maximum heating power is the sum of the three, 10.5. The heating power of the electric heating element in each state is as follows:

[0041]

[0042] Taking an electric heating element with a maximum heating power of 8.4kW as an example, the following setting parameters are provided: the first power A is set to 1.8kW, the second power B is set to 2.8kW, and the third power is set to 3.8kW. The maximum heating power is the sum of the three, 8.4kW. The heating power of the electric heating element in each state is as follows:

[0043]

[0044]

[0045] See Figure 2-Figure 5The electric heating element 40 is a thick film heating body. The heating tube 4 includes a first heating tube 41, a second heating tube 42 and a third heating tube 43 connected in series. The rated powers of the first heating tube 41, the second heating tube 42 and the third heating tube 43 after being energized are different; the rated power of the first heating tube 41 after being energized is a first power A, the rated power of the second heating tube 42 after being energized is a second power B, and the rated power of the third heating tube 43 after being energized is a third power C. The values of the first power A, the second power B and the third power C are an arithmetic increasing series, and the sum of the first power A and the second power B is greater than the third power C; a second temperature sensor 72 is provided on the housing 1, and the second temperature sensor 72 is used to detect The water temperature in the water outlet pipe 3, the temperature information obtained by the second temperature sensor 72 can be transmitted to the servo valve 82, the water temperature in the water outlet pipe 3 will be collected by the second temperature sensor 72, and the collected temperature is compared with the water outlet temperature input by the user. When the collected temperature is higher than the water outlet temperature input by the user, the servo valve 82 increases the opening to increase the flow rate; when the collected temperature is lower than the water outlet temperature input by the user, the servo valve 82 decreases the opening to reduce the flow rate, so that the final water outlet temperature of the water outlet pipe 3 matches the water outlet temperature input by the user; the water outlet temperature realizes closed-loop control logic through the second temperature sensor 72 and the servo valve 82, so as to improve the voltage of the power supply to each heating pipe when the water heater is working, and the power is unstable, resulting in water outlet water. The problem of unstable temperature; a circuit control board 81 is provided on the housing 1, and the heating pipe 4, the control element, the first temperature sensor 71, the second temperature sensor 72 and the electric water pump 6 are all electrically connected to the circuit control board 81. In step S002, the temperature difference required for heating is calculated by the program on the circuit control board 81. In step S003, the heating power required for the electric heating element 40 is calculated by the program on the circuit control board 81; in step S004, the heating pipe that needs to be energized for heating is calculated by the program on the circuit control board 81; in step S006, when the second temperature sensor 72 detects that the water temperature in the water outlet pipe 3 is lower than the water outlet temperature input by the user, the corresponding The heating tube 4 is powered on for heating; when the second temperature sensor 72 detects that the water temperature in the water outlet pipe 3 reaches the water outlet temperature input by the user, the heating tubes 4 are kept powered on for heating, and at the same time, the rotation speed of the electric water pump 6 and the opening of the servo valve 82 are maintained, so that the actual water outlet temperature is maintained at the water outlet temperature input by the user; the second temperature sensor 72 will collect the temperature information of the water outlet, and fine-tune the flow rate through the servo valve 82 to more accurately reach and maintain the water outlet temperature at the set temperature, so as to achieve precise temperature control and constant temperature function, and have a good user experience. Since the servo valve 82 itself has a feedback system, this control method is closed-loop control with high control accuracy; the electric water pump 6 is a speed-adjustable DC motor water pump, and the control element is a relay.

[0046] Example 2:

[0047] See Figure 7 The difference between the second embodiment and the first embodiment is that the third temperature sensor 73 is a probe-type temperature sensor. The metal probe has fast heat conduction and can quickly reflect temperature changes, and the power is cut off more promptly.

[0048] Compared with the prior art, the instant water heater with multi-heating tube combined heating in the present invention controls the outlet water temperature by individually controlling the power on and off of multiple heating tubes, with a simple control structure, low production cost, accurate and reliable control; the heating work of the heating tube is controlled according to the temperature difference between the inlet and outlet water temperatures, and the outlet water temperature is not easily affected by the season and the incoming water temperature, further improving the accuracy of the outlet water temperature and providing a good user experience; through heating tubes of different powers, the heating power of the electric heating element can be changed by energizing different heating tubes; the heating power of the electric heating element can be changed by heating with different single heating tubes, heating with a combination of two heating tubes, or heating with three heating tubes at the same time, and the total heating power of the electric heating element can be adjusted more flexibly; the values of the first power, the second power and the third power are an arithmetically increasing series, and the sum of the first power and the second power is greater than the third power. The value-taking method of this control method can make the heating power value distribution of the electric heating element more uniform under different heating states, that is, the difference between two adjacent powers arranged from small to large has a small fluctuation, so as to meet the heating requirements under each input outlet water temperature.

[0049] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An instantaneous water heater with multiple heating tubes, characterized in that: include: A shell (1) is provided with a water inlet pipe (2), a water outlet pipe (3) and an electric heating element (40), the electric heating element (40) being provided with a water inlet (10) and a water outlet (11), the water inlet pipe (2) being in communication with the water inlet (10), the water outlet pipe (3) being in communication with the water outlet (11), the water inlet pipe (2) being connected to an electric water pump (6), the electric heating element (40) comprising a plurality of heating pipes (4) connected in series, the heating pipes (4) being used to heat water flowing through the heating pipes, the shell (1) being provided with a control element, the number of the control element being the same as the number of the heating pipes (4) being in one-to-one correspondence, the control element being used to control the power on / off of the corresponding heating pipe (4), the shell (1) being provided with a first temperature sensor (71), the first temperature sensor (71) being used to detect the water temperature in the water inlet pipe (2).

2. The instantaneous water heater with multiple heating tubes combined heating according to claim 1, characterized in that: The electric heating element (40) is a thick film heating body, and the heating tube (4) comprises a first heating tube (41), a second heating tube (42) and a third heating tube (43) connected in series, wherein the first heating tube (41), the second heating tube (42) and the third heating tube (43) have different rated powers after being energized.

3. The instantaneous water heater with multiple heating tubes combined heating according to claim 2, characterized in that: The rated power of the first heating tube (41) after being energized is a first power (A), the rated power of the second heating tube (42) after being energized is a second power (B), and the rated power of the third heating tube (43) after being energized is a third power (C), the values of the first power (A), the second power (B) and the third power (C) are an arithmetic increasing series, and the sum of the first power (A) and the second power (B) is greater than the third power (C).

4. The instantaneous water heater with multiple heating tubes as claimed in claim 1, characterized in that: The housing (1) is provided with a second temperature sensor (72), which is used to detect the water temperature in the water outlet pipe (3). The housing (1) is provided with a circuit control board (81), and the heating pipe (4), the control element, the first temperature sensor (71), the second temperature sensor (72) and the electric water pump (6) are all electrically connected to the circuit control board (81).

5. The instantaneous water heater with multiple heating tubes combined heating according to claim 1, characterized in that: The water inlet pipeline (2) is connected to a servo valve (82), the electric water pump (6) is a speed-adjustable DC motor water pump, and the control element is a relay.

6. A control method for an instantaneous water heater with multiple heating tubes for combined heating, based on the instantaneous water heater with multiple heating tubes for combined heating according to any one of claims 1 to 5, characterized in that: The steps include: Step S001: Input the outlet water temperature. The user adjusts the outlet water temperature level to the desired outlet water temperature level through the knob or button on the housing (1); Step S002: Calculate the temperature difference required for heating, detect the water temperature in the water inlet pipe (2) through the first temperature sensor (71), and calculate the temperature difference (Δ) between the water outlet temperature input by the user and the water temperature in the water inlet pipe (2); Step S003, calculating the heating power required by the electric heating element, and calculating the heating power required by the electric heating element (40) based on the temperature difference (Δ) required for heating and the preset water flow rate of the water outlet pipe (3); Step S004: Calculate the heating tube that needs to be energized. The heating power of the electric heating element (40) is the sum of the powers of the heating tubes (4) in the energized state. The heating tube that needs to be energized is calculated based on the heating power required by the electric heating element (40) and the heating power of each heating tube. Step S005: the servo valve adjusts the corresponding flow rate, and the actual water outflow flow rate of the water outflow pipe (3) is adjusted by the servo valve (82) connected to the water inlet pipe (2), so that the actual water outflow flow rate matches the preset water outflow flow rate; Step S006: hot water is discharged. The switch (12) on the housing (1) controls the electric water pump (6) to be powered on and started, and controls the servo valve (82) to be opened, so that the water outlet pipe (3) discharges water. When the actual water outlet flow rate matches the preset water outlet flow rate, the control element controls the heating pipes that need to be powered on to be powered on and heated, so that the sum of the power of each heating pipe matches the heating power required by the electric heating element (40), so that the outlet water temperature of the water outlet pipe (3) is close to the user input water outlet temperature. Step S007: Turn off the water outlet, control the electric water pump (6) to stop rotating, control the servo valve (82) to close, and control the power off of each heating pipe through the switch (12) on the housing (1).

7. The control method of the instantaneous water heater with multiple heating tubes according to claim 6, characterized in that: The electric heating element (40) is a thick film heating body, and the heating tube (4) comprises a first heating tube (41), a second heating tube (42) and a third heating tube (43) connected in series, wherein the first heating tube (41), the second heating tube (42) and the third heating tube (43) have different rated powers after being energized.

8. The control method of the instantaneous water heater with multiple heating tubes according to claim 7, characterized in that: The rated power of the first heating tube (41) after being energized is a first power (A), the rated power of the second heating tube (42) after being energized is a second power (B), and the rated power of the third heating tube (43) after being energized is a third power (C), the values of the first power (A), the second power (B) and the third power (C) are an arithmetic increasing series, and the sum of the first power (A) and the second power (B) is greater than the third power (C).

9. The control method of the instantaneous water heater with multiple heating tubes according to claim 6, characterized in that: The housing (1) is provided with a second temperature sensor (72), which is used to detect the water temperature in the water outlet pipe (3). The temperature information obtained by the second temperature sensor (72) can be transmitted to the servo valve (82). The water temperature in the water outlet pipe (3) is collected by the second temperature sensor (72). The collected temperature is compared with the water outlet temperature input by the user. When the collected temperature is higher than the water outlet temperature input by the user, the servo valve (82) increases the opening to increase the flow rate; when the collected temperature is lower than the water outlet temperature input by the user, the servo valve (82) decreases the opening to reduce the flow rate, so that the final water outlet temperature of the water outlet pipe (3) matches the water outlet temperature input by the user. The housing (1) is provided with a circuit control board (81), and the heating pipe (4), the control element, the first temperature sensor (71), the second temperature sensor (72) and the electric water pump (6) are all connected to the electric control board (81). The circuit control board (81) is electrically connected to the circuit control board (81). In step S002, the temperature difference required for heating is calculated by a program on the circuit control board (81). In step S003, the heating power required for the electric heating element (40) is calculated by a program on the circuit control board (81). In step S004, the heating pipes required for heating are calculated by a program on the circuit control board (81). In step S006, when the second temperature sensor (72) detects that the water temperature in the water outlet pipe (3) is lower than the user input water outlet temperature, the corresponding heating pipe (4) is controlled to be powered on for heating. When the second temperature sensor (72) detects that the water temperature in the water outlet pipe (3) reaches the user input water outlet temperature, the heating pipes (4) are maintained in the powered-on heating state, and the speed of the electric water pump (6) and the opening of the servo valve (82) are maintained, so that the actual water outlet temperature is maintained at the user input water outlet temperature.

10. The control method of the instantaneous water heater with multiple heating tubes according to claim 6, characterized in that: The electric water pump (6) is a speed-adjustable DC motor water pump, and the control element is a relay.

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