Water heater self-adaptive air-fuel ratio device and its control method

Abstract

An embodiment of the present invention discloses a water heater self-adaptive air-fuel ratio device and its control method. The device includes a heat exchanger, an inlet water temperature sensor, an outlet water temperature sensor, a controller, a gas proportional valve, a blower, and a water flow sensor. The controller collects data on water flow rate, outlet water temperature, and inlet water temperature, and calculates the theoretical load Q1 required by the user. The controller collects data on the flow rate of the gas proportional valve and calculates the actual load Q2 of the water heater. The controller compares the difference between Q1 and Q2 and adjusts the air-fuel ratio. By comparing the theoretical load and the actual load, the present invention corrects the blower speed and the current of the proportional valve to achieve the optimal air-fuel ratio.

Description

Technical Field

[0001] The present invention relates to the technical field of household appliances, and particularly to a water heater self - adaptive air - fuel ratio device and a control method thereof. Background Art

[0002] Due to the increasingly widespread use of natural gas, gas water heaters have entered thousands of households. Currently, the gas water heaters produced by gas water heater enterprises are sold and used all over the country, and some enterprises also have a large export volume and are sold in high - altitude areas such as South America, North America, and Africa. However, as the sales and use area of gas water heaters becomes wider, higher requirements are put forward for the adaptability of water heaters. In particular, the altitude varies in different regions. In high - altitude areas, due to the low atmospheric pressure and thin air, it has a great impact on the performance of gas water heaters.

[0003] In plateau areas, the existing water heaters will have a load drop, and the water temperature cannot reach the user - set temperature. In addition, the existing water heaters will also have the phenomenon of failure to ignite, which seriously affects gas safety and user experience. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a water heater self - adaptive air - fuel ratio device and a control method thereof to solve the problem of load drop and make the air - fuel ratio reach the best.

[0005] To solve the above - mentioned technical problem, an embodiment of the present invention provides a water heater self - adaptive air - fuel ratio device, including a heat exchanger, an inlet water temperature sensor, an outlet water temperature sensor, a controller, a gas proportional valve, a blower, and a water flow sensor.

[0006] The controller, according to the user's usage settings, collects the water flow rate, outlet water temperature, and inlet water temperature data in real time through the water flow sensor, the inlet water temperature sensor, and the outlet water temperature sensor, and calculates the theoretical load Q1 required by the user; the controller collects the flow rate data of the gas proportional valve and calculates the actual load Q2 of the water heater; the controller compares the difference between Q1 and Q2 and controls the flow rate of the gas proportional valve and the rotational speed of the blower according to the difference to adjust the air - fuel ratio.

[0007] Further, the controller calculates Q1 and Q2 using the following formula:

[0008] Q1 = C * G(t1 - t2) / 3.6;

[0009] Q2 = L g * q;

[0010] Wherein, C is the specific heat capacity of water, G is the water flow rate detected by the water flow sensor; t1 is the outlet water temperature detected by the outlet water temperature sensor; t2 is the inlet water temperature detected by the inlet water temperature sensor, L gwhere \(F\) is the flow rate of the gas proportional valve; \(q\) is the calorific value of the gas.

[0011] Further, it also includes a pressure gauge for detecting the secondary gas pressure. When the actual load is lower than the theoretical load and the secondary gas pressure is constant, the controller increases the fan speed to increase the air volume.

[0012] Further, the controller adjusts the fan air volume according to the following formula:

[0013] \(Q = U\times I\times K / P\);

[0014] where \(Q\) is the fan air volume; \(U\) is the fan voltage; \(I\) is the fan current; \(K\) is the correction coefficient; \(P\) is the fan air pressure.

[0015] Further, when the water heater's adaptive air-fuel ratio device is turned on and running, the controller executes the ignition mode. The default number of ignition times in the ignition mode is 3 times, each time for 3 - 5 seconds. Among them, for the first ignition, the fan speed is controlled to be the preset normal value. If the ignition fails, the second ignition is carried out, and the fan speed is controlled to be the preset low value. If the ignition fails again, the third ignition is carried out, and the fan speed is set to the preset lowest ignition value.

[0016] Correspondingly, the embodiment of the present invention also provides a control method for a water heater's adaptive air-fuel ratio device, including:

[0017] Theoretical load calculation step: The controller collects the water flow rate, outlet water temperature, and inlet water temperature data in real time through the water flow sensor, inlet water temperature sensor, and outlet water temperature sensor according to the user's usage settings, and calculates the theoretical load \(Q1\) required by the user;

[0018] Actual load calculation step: The controller collects data on the flow rate of the gas proportional valve and calculates the actual load \(Q2\) of the water heater;

[0019] Adaptive air-fuel ratio adjustment step: The controller compares the difference between \(Q1\) and \(Q2\), and controls the flow rate of the gas proportional valve and the fan speed according to the difference to adjust the air-fuel ratio.

[0020] Further, in the theoretical load calculation step and the actual load calculation step, the controller calculates \(Q1\) and \(Q2\) using the following formula:

[0021] \(Q1 = C\times G\times(t1 - t2) / 3.6\);

[0022] \(Q2 = L\) g *q;

[0023] where \(C\) is the specific heat capacity of water, \(G\) is the water flow rate detected by the water flow sensor; \(t1\) is the outlet water temperature detected by the outlet water temperature sensor; \(t2\) is the inlet water temperature detected by the inlet water temperature sensor, \(L\) gwhere is the flow rate of the gas proportional valve; q is the calorific value of the gas.

[0024] Further, in the adaptive air-fuel ratio adjustment step, when the actual load is lower than the theoretical load and the secondary gas pressure is constant, the controller increases the fan speed to increase the air volume.

[0025] Further, the controller adjusts the air volume of the fan according to the following formula:

[0026] Q = U * I * K / P;

[0027] where Q is the air volume of the fan; U is the fan voltage; I is the fan current; K is the correction coefficient; P is the fan air pressure.

[0028] Further, before the theoretical load calculation step, there is also an ignition control step:

[0029] When the adaptive air-fuel ratio device of the water heater is started and running, the controller executes the ignition mode. The default number of ignition times in the ignition mode is 3 times, each time for 3 - 5 seconds. Among them, for the first ignition, the fan speed is controlled to be the preset normal value. If the ignition fails, the second ignition is carried out, and the fan speed is controlled to be the preset low value. If the ignition fails again, the third ignition is carried out, and the fan speed is set to the preset lowest ignition value.

[0030] The beneficial effects of the present invention are as follows: The present invention monitors the water volume and temperature rise through the water volume sensor, the inlet water temperature sensor, and the outlet water temperature sensor, and the controller calculates the theoretical load required by the user; monitors the flow rate of the gas proportional valve and the wind speed of the fan, and the controller calculates the actual load; the controller corrects the fan speed and the current of the proportional valve by comparing the theoretical load and the actual load to achieve the best air-fuel ratio. Description of the Drawings

[0031] Figure 1 is a schematic structural diagram of the adaptive air-fuel ratio device of the water heater in the embodiment of the present invention.

[0032] Explanation of the Reference Numerals in the Drawings

[0033] Heat exchanger 1, inlet water temperature sensor 2, outlet water temperature sensor 3, controller 4, gas proportional valve 5, burner 6, water flow sensor 7, cold water inlet 8, hot water outlet 9. Detailed Embodiment

[0034] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0035] In the embodiments of the present invention, if there are directional indications (such as up, down, left, right, front, back...), they are only used to explain the relative positional relationship and movement conditions between components in a certain specific posture (as shown in the attached drawings). If the specific posture changes, the directional indications will also change accordingly.

[0036] In addition, in the present invention, the descriptions such as "first" and "second" are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features.

[0037] Please refer to Figure 1 , the water heater adaptive air-fuel ratio device of the embodiments of the present invention includes a heat exchanger, an inlet water temperature sensor, an outlet water temperature sensor, a controller, a gas proportional valve, a blower (not shown in the figure), a water flow sensor, and a burner. The inlet water temperature sensor and the water flow sensor are arranged at the cold water inlet, and the outlet water temperature sensor is arranged at the hot water outlet. This part of the structure is a common structure of existing water heaters. The controller is connected to the inlet water temperature sensor, the outlet water temperature sensor, the gas proportional valve, the blower, and the water flow sensor through wires.

[0038] When the water heater adaptive air-fuel ratio device is started and operated, the controller, according to the user's usage settings (such as the outlet water temperature and outlet water flow set by the user), collects the water flow, outlet water temperature, and inlet water temperature data in real time through the water flow sensor, the inlet water temperature sensor, and the outlet water temperature sensor, and calculates the theoretical load Q1 required by the user. The controller collects the flow rate data of the gas proportional valve and calculates the actual load Q2 of the water heater. The controller compares the difference between Q1 and Q2 and controls the flow rate of the gas proportional valve and the rotational speed of the blower according to the difference, so that Q2 approaches Q1 (Q1 = Q2) and the air-fuel ratio reaches the optimum.

[0039] As an implementation manner, the controller calculates Q1 and Q2 using the following formula:

[0040] Q1 = C * G * (t1 - t2) / 3.6;

[0041] Q2 = L g * q;

[0042] where C is the specific heat capacity of water, G is the water flow rate detected by the water flow sensor; t1 is the outlet water temperature detected by the outlet water temperature sensor; t2 is the inlet water temperature detected by the inlet water temperature sensor, L g is the flow rate of the gas proportional valve; q is the calorific value of the gas. Among them, ; μ is the nozzle coefficient of the gas proportional valve, d is the nozzle diameter of the gas proportional valve, p is the nozzle pressure, and s is the relative density of the gas.

[0043] As an implementation manner, the water heater adaptive air-fuel ratio device further includes a pressure gauge for detecting the secondary gas pressure.

[0044] The controller has a power-off memory function. When used next time, the controller will default to the previous settings and make corrections when the data acquisition environment changes. When the actual load is lower than the theoretical load and the secondary gas pressure is constant (that is, the pressure before the gas enters the valve body does not change, but the actual heat load is lower than the theoretical heat load, indicating that the ambient air pressure is low and the gas combustion is incomplete), the controller increases the fan speed and the air volume.

[0045] As an implementation manner, the controller adjusts the fan air volume according to the following formula:

[0046] Q = U * I * K / P;

[0047] Wherein, Q is the fan air volume; U is the fan voltage; I is the fan current; K is a correction factor; P is the fan air pressure. The value of K has three ranges: low 0.8 - 1, normal 1 - 1.1, high 1.1 - 1.4.

[0048] As an implementation manner, when the water heater adaptive air-fuel ratio device is started and running, the controller executes the ignition mode. The default number of ignition times in the ignition mode is 3 times, each time for 3 - 5 seconds. Among them, for the first ignition, the fan wind speed is controlled to be the preset normal value. If the ignition fails, the second ignition is carried out, and the fan wind speed is controlled to be the preset low value. If the ignition fails again, the third ignition is carried out, and the fan wind speed is set to the preset lowest ignition value.

[0049] The control method of the water heater adaptive air-fuel ratio device according to the embodiment of the present invention includes a theoretical load calculation step, an actual load calculation step, and an adaptive air-fuel ratio adjustment step.

[0050] Theoretical load calculation step: The controller calculates the theoretical load Q1 required by the user by collecting the water flow rate, outlet water temperature, and inlet water temperature data in real time through the water flow sensor, inlet water temperature sensor, and outlet water temperature sensor according to the user's usage settings.

[0051] Actual load calculation step: The controller collects data on the flow rate of the gas proportional valve and calculates the actual load Q2 of the water heater.

[0052] Adaptive air-fuel ratio adjustment step: The controller compares the difference between Q1 and Q2 and controls the gas proportional valve flow rate and the fan speed according to the difference to make the air-fuel ratio reach the best.

[0053] [[ID=3l]]As an implementation manner, in the theoretical load calculation step and the actual load calculation step, the controller calculates Q1 and Q2 using the following formula:

[0054] Q1 = C * G * (t1 - t2) / 3.6;

[0055] Q2 = L g * q;

[0056] Wherein, C is the specific heat capacity of water, G is the water flow rate detected by the water flow sensor; t1 is the outlet water temperature detected by the outlet water temperature sensor; t2 is the inlet water temperature detected by the inlet water temperature sensor, L g is the flow rate of the gas proportional valve; q is the calorific value of the gas.

[0057] As an implementation manner, in the adaptive air-fuel ratio adjustment step, when the actual load is lower than the theoretical load and the secondary gas pressure is constant, the controller increases the fan speed and increases the air volume.

[0058] As an implementation manner, the controller adjusts the fan air volume according to the following formula:

[0059] Q = U * I * K / P;

[0060] Wherein, Q is the fan air volume; U is the fan voltage; I is the fan current; K is the correction coefficient; P is the fan air pressure.

[0061] As an implementation manner, before the theoretical load calculation step, there is also an ignition control step:

[0062] When the water heater adaptive air-fuel ratio device is turned on and running, the controller executes the ignition mode. The default number of ignition times in the ignition mode is 3 times, 3 - 5 seconds each time. Among them, for the first ignition, the fan wind speed is controlled at the preset normal value. If the ignition fails, the second ignition is carried out, and the fan wind speed is controlled at the preset low value. If the ignition fails again, the third ignition is carried out, and the fan wind speed is set at the preset lowest ignition value.

[0063] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalent scope.

Claims

1. An adaptive air-fuel ratio device for a water heater, comprising a heat exchanger, a water inlet temperature sensor, a water outlet temperature sensor, a controller, a gas proportional valve, a blower, and a water flow sensor, characterized in that the controller, according to the user's usage settings, collects data on water flow rate, water outlet temperature, and water inlet temperature in real time through the water flow sensor, the water inlet temperature sensor, and the water outlet temperature sensor, and calculates the theoretical load Q1 required by the user; the controller collects data on the flow rate of the gas proportional valve and calculates the actual load Q2 of the water heater; the controller compares the difference between Q1 and Q2 and controls the flow rate of the gas proportional valve and the rotational speed of the blower according to the difference to adjust the air-fuel ratio; the controller calculates Q1 and Q2 using the following formula: Q1 = C * G * (t1 - t2) / 3.6; Q2 = L g *q; where C is the specific heat capacity of water, G is the water flow rate detected by the water flow sensor; t1 is the outlet water temperature detected by the outlet water temperature sensor; t2 is the inlet water temperature detected by the inlet water temperature sensor, and L g is the flow rate of the gas proportional valve; q is the calorific value of the gas; the adaptive air-fuel ratio device for the water heater further includes a pressure gauge for detecting the secondary gas pressure. When the actual load is lower than the theoretical load and the secondary gas pressure is constant, the controller increases the rotational speed of the blower and increases the air volume; when the adaptive air-fuel ratio device of the water heater starts to operate, the controller executes an ignition mode. The default number of ignition times in the ignition mode is 3 times, each time for 3 - 5 seconds. Among them, for the first ignition, the blower air speed is controlled at a preset normal value. If the ignition fails, the second ignition is carried out, and the blower air speed is controlled at a preset lower value. If the ignition fails again, the third ignition is carried out, and the blower air speed is set at the preset lowest ignition value.

2. The water heater self - adapting air - fuel ratio device according to claim 1, characterized in that, the controller adjusts the blower air volume according to the following formula: Q = U * I * K / P; where Q is the blower air volume; U is the blower voltage; I is the blower current; K is a correction factor; P is the blower air pressure.

3. A control method for an air-fuel ratio self-adaptive device of a water heater, characterized in that, including: Theoretical load calculation step: The controller, according to the user's usage settings, collects data on water flow rate, water outlet temperature, and water inlet temperature in real time through the water flow sensor, the water inlet temperature sensor, and the water outlet temperature sensor, and calculates the theoretical load Q1 required by the user; Actual load calculation step: The controller collects data on the flow rate of the gas proportional valve and calculates the actual load Q2 of the water heater; Adaptive air-fuel ratio adjustment step: The controller compares the difference between Q1 and Q2 and controls the flow rate of the gas proportional valve and the rotational speed of the blower according to the difference to adjust the air-fuel ratio; In the theoretical load calculation step and the actual load calculation step, the controller calculates Q1 and Q2 using the following formula: Q1 = C * G * (t1 - t2) / 3.6; Q2 = L g *q; where C is the specific heat capacity of water, G is the water flow rate detected by the water flow sensor; t1 is the outlet water temperature detected by the outlet water temperature sensor; t2 is the inlet water temperature detected by the inlet water temperature sensor, L g is the flow rate of the gas proportional valve; q is the calorific value of the gas; In the adaptive air-fuel ratio adjustment step, when the actual load is lower than the theoretical load and the secondary gas pressure is constant, the controller increases the rotational speed of the blower and increases the air volume; Before the theoretical load calculation step, there is also an ignition control step: when the adaptive air-fuel ratio device of the water heater starts to operate, the controller executes an ignition mode. The default number of ignition times in the ignition mode is 3 times, each time for 3 - 5 seconds. Among them, for the first ignition, the blower air speed is controlled at a preset normal value. If the ignition fails, the second ignition is carried out, and the blower air speed is controlled at a preset lower value. If the ignition fails again, the third ignition is carried out, and the blower air speed is set at the preset lowest ignition value.

4. The control method of the water heater self - adapting air - fuel ratio device according to claim 3, characterized in that, The controller adjusts the blower air volume according to the following formula: Q = U * I * K / P; Among them, Q is the air volume of the fan; U is the voltage of the fan; I is the current of the fan; K is the correction coefficient; P is the air pressure of the fan.

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