A constant temperature control method for gas water heater

Abstract

The present invention discloses a constant temperature control method for a gas water heater. The gas water heater applies the constant temperature control method in this embodiment to collect the heat energy conversion relationship, calculate the heat conversion relationship, and calculate the current water flow state through the water adjustment algorithm under different water flow environments, thereby calculating the current value and gear value output by the proportional valve through the change of the water flow, and then controlling the opening of the gas proportional valve according to the current value and gear value output by the proportional valve to make the water outlet temperature close to the preset target temperature, so that the gas water heater can achieve constant temperature control. The method is simple and reliable, and can enable the gas water heater to maintain a constant water outlet temperature under different water flow environments, thereby bringing users a good bathing experience.

Description

Technical Field

[0001] The present invention relates to the technical field of water heaters, and in particular to a constant temperature control method for a gas water heater. Background Art

[0002] In the related art, most gas water heaters are subject to differences in water pressure, air pressure and various components, and the outlet water temperature often fluctuates, causing users to have a bad bathing experience. Therefore, the problem of constant temperature of the outlet water of the gas water heater has become a technical problem that needs to be solved urgently in existing gas water heaters. Summary of the invention

[0003] The present invention aims to solve at least one of the problems existing in the existing related technologies to a certain extent. To this end, the present invention proposes a constant temperature control method for a gas water heater. The method is simple and reliable, and can enable the gas water heater to maintain a constant water outlet temperature under different water flow environments, thereby giving users a good bathing experience.

[0004] The above purpose is achieved through the following technical solutions:

[0005] A constant temperature control method for a gas water heater, the constant temperature control method comprising:

[0006] After starting the gas water heater and igniting it;

[0007] Collecting an initial water flow value L of the gas water heater;

[0008] Determining whether the initial water flow value L remains constant;

[0009] If yes, the heating energy E0 in the current state is obtained by calculation and PID algorithm control is performed;

[0010] If not, the water flow is collected again to sequentially obtain a first water flow value L1 and a plurality of water flow values ​​L2;

[0011] comparing the first water flow value L1 with a difference between any one of the plurality of water flow values ​​and a first set water flow change amount Q1;

[0012] If the first water flow value L1 is less than the difference between any one of the plurality of water flow values ​​and the first set water flow change amount Q1, it is determined that the current water flow is decreasing, and the first water adjustment algorithm is used to calculate to obtain the heating energy E1 in the current state;

[0013] If the first water flow value L1 is greater than the sum of any one of the multiple water flow values ​​and the first set water flow change Q1, it is determined that the current water flow has increased, and the second water regulation algorithm is used to calculate to obtain the heating energy E2 under the current state.

[0014] In some implementations, the step of collecting the initial water flow value L of the gas water heater specifically includes:

[0015] Collecting a plurality of water flow values ​​within a preset time to obtain first data, and calculating an average value of the first data to obtain a water flow value L0;

[0016] Continue to collect water flow and obtain multiple water flow values ​​L0 through calculation;

[0017] After removing the maximum value and the minimum value from the plurality of water flow values ​​L0, an average value is calculated for the remaining water flow values ​​L0 to obtain an initial water flow value L.

[0018] In some embodiments, the heating energy E0 in the current state is calculated by the following calculation formula:

[0019] E0=L×△T, where L is the initial water flow value and △T is the temperature change.

[0020] In some implementations, the first water transfer algorithm is specifically:

[0021] E1=E0-△Q1×△T, where E0 is the heating energy under a constant state, △Q1 is the difference between the first water flow value L1 and the most recently collected water flow value among the multiple water flow values ​​L2, and △T is the temperature change.

[0022] In some implementations, the second water transfer algorithm is specifically:

[0023] E2=E0+△Q1×△T, where E0 is the heating energy under constant state, △Q1 is the difference between the first water flow value L1 and the most recently collected water flow value among the multiple water flow values ​​L2, and △T is the temperature change.

[0024] In some embodiments, the step after calculating according to the first water adjustment algorithm to obtain the heating energy E1 in the current state further includes:

[0025] After obtaining the heating energy E1 in the current state, the first water flow value L1 is set as the second set water flow change amount Q2;

[0026] Continue to collect the water flow rate again to obtain multiple water flow rate values ​​L3 in sequence;

[0027] Until any one of the plurality of water flow values ​​L3 is greater than the difference between the second set water flow change amount Q2 and the first preset threshold value;

[0028] The third water adjustment algorithm is used to calculate to obtain the heating energy E3 under the current state.

[0029] In some implementations, the third water adjustment algorithm is specifically:

[0030] E3=E1-△Q2×△T, where E1 is the heating energy under the last water flow state, △Q2 is the difference between the first water flow value and the last water flow value in the multiple water flow values ​​L3, and △T is the temperature change.

[0031] In some embodiments, the step after calculating according to the second water adjustment algorithm to obtain the heating energy E2 in the current state further includes:

[0032] After obtaining the heating energy E2 in the current state, the first water flow value L1 is set as the third set water flow change amount Q3;

[0033] Continue to collect the water flow rate again to obtain multiple water flow rate values ​​L4 in sequence;

[0034] Until any one of the plurality of water flow values ​​L4 is greater than the sum of the third set water flow change Q3 and the second preset threshold value;

[0035] The fourth water regulation algorithm is used to calculate to obtain the heating energy E4 under the current state.

[0036] In some implementations, the fourth water adjustment algorithm is specifically:

[0037] E4=E2+△Q3×△T, where E2 is the heating energy under the last water flow state, △Q3 is the difference between the first water flow value and the last water flow value in the multiple water flow values ​​L4, and △T is the temperature change.

[0038] In some embodiments, the constant temperature control method further comprises:

[0039] If the water flow value collected at any time is less than the preset safety factor, the gas water heater is turned off.

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] 1. The constant temperature control method of the gas water heater of the present invention is simple and reliable, and can enable the gas water heater to maintain a constant water outlet temperature under different water flow environments, thereby bringing users a good bathing experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 1 is a flow chart of a method for controlling a gap in an embodiment of the present invention;

[0043] Figure 2is a graph showing the relationship between the sampling period and the water flow rate in an embodiment of the present invention;

[0044] Figure 3 It is a control parameter table in the embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of the technical solution for protection of the present invention.

[0046] like Figures 1 to 3 As shown, the present embodiment provides a constant temperature control method for a gas water heater. The gas water heater applies the constant temperature control method in the present embodiment to collect the heat energy conversion relationship and calculate the heat conversion relationship. Under different water flow environments, the water adjustment algorithm is used to calculate to determine the current state of the water flow, so as to calculate the current value and the gear value output by the proportional valve through the change of the water flow, and then the opening of the gas proportional valve is controlled according to the current value and the gear value output by the proportional valve to make the water outlet temperature close to the preset target temperature, so that the gas water heater can achieve constant temperature control. The method is simple and reliable, and can enable the gas water heater to maintain a constant water outlet temperature under different water flow environments, thereby bringing users a good bathing experience.

[0047] The constant temperature control method of the gas water heater specifically includes the following steps:

[0048] Step S101, start the gas water heater and ignite it for combustion.

[0049] In this embodiment, the gas water heater is in a standby state and starts to ignite after detecting a water flow signal. If no water flow signal is detected, the proportional valve is closed to extinguish the flame and stop working.

[0050] Step S102, collecting the initial water flow value L of the gas water heater.

[0051] In this embodiment, a plurality of water flow values ​​are collected within a preset time to obtain first data, and the first data are averaged to obtain the water flow value L0;

[0052] Continue to collect water flow and obtain multiple water flow values ​​L0 through calculation;

[0053] After removing the maximum value and the minimum value from the multiple water flow values ​​L0, the average value of the remaining water flow values ​​L0 is calculated to obtain the initial water flow value L.

[0054] In this embodiment, the sampling period is 4 water flow pulses and the average value is taken to obtain the water flow value L0. If the water flow is 1L / min, 8 pulse signals can be collected every 1s. If the water flow is 2L / min, 1 pulse signal can be collected every 62.5ms. If the water flow is 10L / min, 1 pulse signal can be collected every 12.5ms. In addition, in this embodiment, the water flow is continuously collected and calculated to obtain 10 water flow values ​​L0. The maximum and minimum values ​​of the 10 water flow values ​​L0 are removed, and then the remaining 8 water flow values ​​are averaged to obtain the initial water flow value L. In this way, the water flow signal can be made more stable through this sampling method, thereby further eliminating the sampling error.

[0055] Step S103, determining whether the initial water flow value L remains constant.

[0056] If yes, then go to step S113, calculate to obtain the heating energy E0 in the current state and perform PID algorithm control;

[0057] If not, the process proceeds to step S123 to collect the water flow rate again to sequentially obtain the first water flow rate value L1 and a plurality of water flow rate values ​​L2.

[0058] In this embodiment, if the user suddenly opens another faucet or closes the faucet, causing the current water flow to change suddenly, then by monitoring whether the initial water flow value L changes suddenly, it can be determined whether the initial water flow value L remains constant. When the water flow does not remain constant, continuing to use the PID algorithm will cause the outlet water temperature to take a long time to reach a stable value. The use of the above control scheme can quickly identify the change in water flow, thereby quickly calculating the corresponding heating energy. According to the calculated heating energy and through the preset control parameters, the opening of the proportional valve and the number of gears can be calculated to achieve constant temperature control.

[0059] In this embodiment, if the initial water flow value L remains unchanged to maintain a constant state, the heating energy E0 in the current state can be calculated by the following calculation formula: E0=L×△T, where L is the initial water flow value and △T is the temperature change. The opening degree and the number of gears of the proportional valve can be calculated based on the calculated heating energy E0 and the preset control parameters, thereby performing constant temperature control through the PID algorithm.

[0060] In this embodiment, if the initial water flow rate value L undergoes a mutation, that is, when the initial water flow rate value L does not remain constant, the above acquisition period, namely 4 water flow pulses, is used for sampling. Within the period of 625 ms - 1.25 s, the number of samples is 100 sampling signals collected each time, thus obtaining the following sampling data: a[0], a[1], …, a

[99] , where a[0] is the latest sampled set of values, a

[99] is the oldest set of values, and a[0], a[1], …, a

[99] are updated each time a sample is taken. Thus, the updated a[0] is the first water flow rate value L1, and the updated a[1], …, a

[99] are multiple water flow rate values L2.

[0061] Step S104: Compare the difference between the first water flow rate value L1 and the difference between any one of the multiple water flow rate values and the first set water flow change Q1.

[0062] Step S114: If the first water flow rate value L1 is less than the difference between any one of the multiple water flow rate values and the first set water flow change Q1, then it is determined that the current water flow rate has decreased, and calculation is performed according to the first water regulation algorithm to obtain the heating energy E1 in the current state.

[0063] Step S124: If the first water flow rate value L1 is greater than the sum of any one of the multiple water flow rate values and the first set water flow change Q1, then it is determined that the current water flow rate has increased, and calculation is performed according to the second water regulation algorithm to obtain the heating energy E2 in the current state.

[0064] In this embodiment, it is judged whether the first water flow rate value L1 is less than the difference between any one of the multiple water flow rate values and the first set water flow change Q1 to determine whether the current water flow rate mutation is due to a decrease in the water flow rate value or an increase in the water flow rate value.

[0065] In this embodiment, if the first water flow rate value L1 is less than the difference between any one of the multiple water flow rate values and the first set water flow change Q1, that is, a[0] < a[i] - Q1, where i ranges from 1 to 99, and Q1 is preferably set to 1 - 2 L / min, then it is determined that the current water flow rate has decreased. Then, the heating energy E1 in the current state is calculated through the first water regulation algorithm: E1 = E0 - △Q1 × △T, where E0 is the heating energy in the constant state, △Q1 is the difference between the first water flow rate value L1 and the latest sampled water flow rate value among the multiple water flow rate values L2, and △T is the temperature change. Thus, based on the calculated heating energy E1 and through preset control parameters, the opening degree and gear position of the proportional valve can be deduced, and constant temperature control can be achieved.

[0066] In this embodiment, after obtaining the heating energy E1 in the current state, the first water flow rate value L1 is set to the second set water flow change amount Q2, that is, the updated a[0] is set to the second set water flow change amount Q2, and the water flow rate is collected again to sequentially obtain a plurality of water flow rate values L3, that is, continue to collect to obtain 20 sets of water flow rate data b[0], b[1]... b

[19] , until any one of the plurality of water flow rate values L3 is greater than the difference between the second set water flow change amount Q2 and the first preset threshold value, that is, b[i] < Q2 - 0.5, where i is from 0 to 19. Then, calculate according to the third water regulation algorithm to obtain the heating energy E3 in the current state. The third water regulation algorithm is specifically: E3 = E1 - △Q2 × △T, where E1 is the heating energy in the previous water flow rate state, △Q2 is the difference between the first water flow rate value and the last water flow rate value among the plurality of water flow rate values L3, and △T is the temperature change amount. Thus, according to the calculated heating energy E3 and through the preset control parameters, the opening degree and gear position of the proportional valve can be deduced to achieve constant temperature control.

[0067] In this embodiment, if the first water flow rate value L1 is greater than the sum of any one of the plurality of water flow rate values and the first set water flow change amount Q1, that is, a[0] > a[i] + Q1, where i is from 1 to 99, and Q1 is preferably set to 1 - 2 L / min, it is determined that the current water flow rate becomes larger. Then, calculate the heating energy E2 in the current state through the second water regulation algorithm: E2 = E0 + △Q1 × △T, where E0 is the heating energy in the constant state, △Q1 is the difference between the first water flow rate value L1 and the latest collected water flow rate value among the plurality of water flow rate values L2, and △T is the temperature change amount. Thus, according to the calculated heating energy E2 and through the preset control parameters, the opening degree and gear position of the proportional valve can be deduced to achieve constant temperature control.

[0068] In this embodiment, after obtaining the heating energy E2 in the current state, the first water flow value L1 is set to the third set water flow change amount Q3, that is, the updated a[0] is set to the third set water flow change amount Q3, and the water flow is collected again to obtain multiple water flow values ​​L4 in sequence, that is, continue to collect to obtain 20 groups of water flow data c[0], c[1]...c

[19] , until any water flow value among the multiple water flow values ​​L4 is greater than the sum of the second set water flow change amount Q3 and the second preset threshold value, that is, c[i]>Q2 +0.5, where i is 0 to 19, and then the fourth water regulation algorithm is used to calculate to obtain the heating energy E4 under the current state. The fourth water regulation algorithm is specifically: E4=E2+△Q3×△T, where E2 is the heating energy under the previous water flow state, △Q3 is the difference between the first water flow value and the last water flow value in multiple water flow values ​​L4, and △T is the temperature change. Therefore, according to the calculated heating energy E4 and through the preset control parameters, the opening of the proportional valve and the number of gears can be calculated to achieve constant temperature control.

[0069] In this embodiment, if the water flow value collected at any time is less than the preset safety factor, the gas water heater is turned off to prevent overheating or dry burning due to small flow heating. The preset safety factor is preferably 2.0L / min, but is not limited to the above value, and can also be set to other more appropriate values ​​according to actual needs.

[0070] In this embodiment, the heat conservation model of the gas water heater is hot water heating heat = gas combustion heat - heat dissipation heat. The hot water heating heat can be obtained by the formula E = CM△T, that is, E ∝ Q×△T. In addition, the effective energy of "gas combustion energy - heat dissipation heat" can be considered to be proportional to the gas proportional valve.

[0071] Set the energy level E = Q × △ T, from which we can get the ratio E ∝ B.

[0072] PID control model: Q, T 入 , T 目标 As a known quantity, the proportion of B is obtained by the proportional relationship, and T is obtained at this time 出 , by controlling the deviation Err=T 出 -T 目标 PID operation is performed to continuously correct the B ratio so that Err approaches 0.

[0073] The constant temperature model in this embodiment illustrates that the combustion and heating system is regarded as a whole, focusing only on the gas input and the output of temperature*flow, and controlling the input through the difference of the output to form a closed-loop control, so that the gas system has a certain degree of adaptability. However, the temperature sensor delay constant, flame combustion completeness, gas purity, gas pressure stability, etc. will affect the control stability of the system. For example, the temperature sensor delay constant (thermal inertia, hysteresis) is 1.8S.

[0074] In this embodiment, if Figure 3 As shown, the fire grate of the gas water heater is described by taking 2-4-6 sections as an example. Figure 3 PH is the maximum load of the whole machine, that is, the proportional valve opening is the largest at this time, PL is the maximum load of the whole machine, that is, the proportional valve opening is the largest at this time, Figure 3 The parameters in the above need to be entered into the controller program for load calculation, so as to realize accurate control of the opening and segmented gear position of the proportional valve. In this embodiment, the energy level is used as the control object in the program control. If the current Q×△T=2000, the gear is first selected as the 2nd gear, and then the proportional valve current is proportional to the energy level, so the proportional valve current is obtained as = (2000-880) / (2160-880) * (186-120) + 120.

[0075] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A constant temperature control method for a gas water heater, It is characterized in that The constant temperature control method comprises: After starting the gas water heater and igniting it; Collecting an initial water flow value L of the gas water heater; By monitoring whether the initial water flow value L changes suddenly, it is determined whether the initial water flow value L remains constant; if so, the heating energy E0 in the current state is obtained by calculation and PID algorithm control is performed; if not, the water flow is collected again to obtain the first water flow value L1 and multiple water flow values ​​L2 in sequence; Compare the first water flow value L1 with the difference between any one of the multiple water flow values ​​and the first set water flow change amount Q1; if the first water flow value L1 is less than the difference between any one of the multiple water flow values ​​and the first set water flow change amount Q1, it is determined that the current water flow has decreased, and the first water adjustment algorithm is used to calculate to obtain the heating energy E1 in the current state; if the first water flow value L1 is greater than the sum of any one of the multiple water flow values ​​and the first set water flow change amount Q1, it is determined that the current water flow has increased, and the second water adjustment algorithm is used to calculate to obtain the heating energy E2 in the current state; The heating energy E0 in the current state is calculated by the following calculation formula: E0=L×△T, where L is the initial water flow value and △T is the temperature change; The step of collecting the initial water flow value L of the gas water heater specifically includes: Collecting a plurality of water flow values ​​within a preset time to obtain first data, and calculating an average value of the first data to obtain a water flow value L0; Continue to collect water flow and obtain multiple water flow values ​​L0 through calculation; After removing the maximum value and the minimum value from the plurality of water flow values ​​L0, an average value is calculated for the remaining water flow values ​​L0 to obtain an initial water flow value L.

2. A constant temperature control method for a gas water heater according to claim 1, It is characterized in that The first water transfer algorithm is specifically: E1=E0-△Q1×△T, where E0 is the heating energy under a constant state, △Q1 is the difference between the first water flow value L1 and the most recently collected water flow value among the multiple water flow values ​​L2, and △T is the temperature change.

3. A constant temperature control method for a gas water heater according to claim 1, It is characterized in that The second water transfer algorithm is specifically: E2=E0+△Q1×△T, where E0 is the heating energy under constant state, △Q1 is the difference between the first water flow value L1 and the most recently collected water flow value among the multiple water flow values ​​L2, and △T is the temperature change.

4. A constant temperature control method for a gas water heater according to claim 1, It is characterized in that The step after calculating according to the first water adjustment algorithm to obtain the heating energy E1 under the current state also includes: After obtaining the heating energy E1 in the current state, the first water flow value L1 is set as the second set water flow change amount Q2; Continue to collect the water flow rate again to obtain multiple water flow rate values ​​L3 in sequence; Until any one of the plurality of water flow values ​​L3 is greater than the difference between the second set water flow change amount Q2 and the first preset threshold value; The third water adjustment algorithm is used to calculate to obtain the heating energy E3 under the current state.

5. A constant temperature control method for a gas water heater according to claim 4, It is characterized in that The third water transfer algorithm is specifically: E3=E1-△Q2×△T, where E1 is the heating energy under the last water flow state, △Q2 is the difference between the first water flow value and the last water flow value in the multiple water flow values ​​L3, and △T is the temperature change.

6. A constant temperature control method for a gas water heater according to claim 1, It is characterized in that The step after calculating according to the second water adjustment algorithm to obtain the heating energy E2 in the current state also includes: After obtaining the heating energy E2 in the current state, the first water flow value L1 is set as the third set water flow change amount Q3; Continue to collect the water flow rate again to obtain multiple water flow rate values ​​L4 in sequence; Until any one of the plurality of water flow values ​​L4 is greater than the sum of the third set water flow change Q3 and the second preset threshold value; The fourth water regulation algorithm is used to calculate to obtain the heating energy E4 under the current state.

7. A constant temperature control method for a gas water heater according to claim 6, It is characterized in that The fourth water transfer algorithm is specifically: E4=E2+△Q3×△T, where E2 is the heating energy under the last water flow state, △Q3 is the difference between the first water flow value and the last water flow value in the multiple water flow values ​​L4, and △T is the temperature change.

8. A constant temperature control method for a gas water heater according to any one of claims 1 to 7, It is characterized in that The constant temperature control method also includes: If the water flow value collected at any time is less than the preset safety factor, the gas water heater is turned off.

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