Premixer, gas water heater and wind pressure protection method thereof

Abstract

The present invention provides a premixer, a gas water heater and a wind pressure protection method thereof. The premixer includes a gas chamber, an air chamber and a premixing chamber. The gas chamber conveys gas through one or more gas channels, and the air chamber conveys air through a venturi channel corresponding to the gas channel. The gas channel is located in the venturi channel so that the air in the venturi channel can induce the gas in the gas channel. At least one venturi channel is provided with a flap that can cover the outlet of the venturi channel. The flap can separate the venturi channel and the premixing chamber, and can be turned over by wind force so that the gas and air enter the premixing chamber for mixing. The air flow channel and the gas flow channel of the premixer of the present invention are separated first and then merged, and the structure of the air flow channel and the venturi channel increases the wind pressure, so that the air has a stronger ability to induce the gas. In addition, a flap driven by wind force is provided at the outlet of the venturi channel, which is convenient for obtaining a larger range of load ratios to meet water demand.

Description

Technical Field

[0001] The present invention relates to a gas mixing device, in particular to a premixer. In addition, the present invention also relates to a gas water heater comprising the premixer and a wind pressure protection method for the gas water heater. Background Art

[0002] China's economy is in a critical period of transformation. In order to further reduce the environmental problems caused by the consumption of primary energy (especially coal and oil) in people's production and life, the government is actively encouraging the application of natural gas. Burners are a general term for devices that spray fuel and air in a certain way to mix (or spray mixed) and burn. Burners are divided into industrial burners, burners, civil burners, and special burners according to their types and application fields. The existing burners of household gas water heaters and heating water boilers are designed with partial premixed combustion and full premixed combustion. In the partial premixed combustion mode, the gas is only mixed with part of the air before combustion, and secondary air is required during combustion, so the combustion is incomplete; secondly, the air coefficient is large (generally close to or even more than 2), the combustion flame temperature is low, and due to incomplete combustion, more harmful gases such as CO and NOx will be produced, which does not meet the requirements of environmental protection. The full premixed combustion mode has the advantages of small air coefficient, high flame temperature, full combustion, and low CO and NOx content in the combustion products, so the full premixed combustion mode is more advocated.

[0003] However, the premixer (Venturi) of the existing fully premixed gas water heater (wall-mounted boiler) has the following defects: (1) It can only premix air and gas, and cannot use gas to induce air, or use air to induce gas, so that they can automatically match and obtain a suitable air-fuel ratio; (2) The use of a proportional valve to adjust the air-fuel ratio is not only costly, but also unable to obtain a larger adjustment ratio to meet the user's wide range of hot water needs; (3) The wind pressure is read on the air inlet pipe (i.e., the silencer), and the signal is transmitted to the wind pressure switch. When the wind pressure sensor reaches the closing value, the circuit is disconnected for wind pressure protection; recovery When the start value of the wind pressure sensor is reached, it is turned on again. The wind pressure read on the air inlet pipe is far away from the fan, and the wind pressure value is easily affected by the sealing of the air inlet pipe (generally a snap connection), which is unstable. Moreover, the wind pressure switch can only set a start value and a close value, and cannot provide wind pressure protection for the full load section; (4) The gas pressure cannot be obtained, which is not conducive to detecting the gas front pressure (i.e., gas secondary pressure) of the premixer nozzle; (5) The existing premixer (Venturi) cannot obtain a better small load combustion condition, resulting in poor smoke emissions and backfire at small loads. Summary of the invention

[0004] The problem to be solved by the present invention on one hand is to provide a premixer which can not only enhance the ability of air to induce fuel gas, but also obtain a wider range of load ratios to meet different water demands of users.

[0005] The problem to be solved by the second aspect of the present invention is to provide a gas water heater, the premixer of which can not only enhance the ability of air to induce gas, but also obtain a wider range of load ratios to meet different water needs of users.

[0006] The problem to be solved by the third aspect of the present invention is to provide a wind pressure protection method for a gas water heater, which can judge the fault type and alarm by comparing the measured values ​​of the gas secondary pressure and wind pressure with their respective upper and lower limits.

[0007] The problem to be solved by the fourth aspect of the present invention is to provide a minimum load protection method for a gas water heater, which can improve the wind resistance of the gas water heater in a low-load combustion state.

[0008] In order to achieve the above-mentioned objectives, the present invention provides a premixer on one hand, which includes a gas chamber, an air chamber and a premixing chamber, wherein the gas chamber transports gas through one or more gas channels, and the air chamber transports air through a Venturi channel corresponding to the gas channel, and the gas channel is located in the Venturi channel, so that the air in the Venturi channel can induce the gas in the gas channel and enter the premixing chamber for premixing; at least one of the Venturi channels is provided with a flap that can cover the outlet of the Venturi channel, and the flap can separate the Venturi channel and the premixing chamber, and can be flipped by wind force so that the gas and air enter the premixing chamber for mixing.

[0009] Preferably, a boss capable of blocking the outlet of the Venturi channel is provided on the flap.

[0010] Further preferably, the boss is a cylinder or a beveled cylinder.

[0011] Preferably, a nozzle with an injection direction pointing to the premixing chamber is provided in the gas channel.

[0012] Preferably, the bottom of the air cavity is formed as a guide inclined plate portion capable of guiding air.

[0013] Preferably, a gas pressure nozzle is provided on the gas chamber, and a wind pressure nozzle is provided on the Venturi channel.

[0014] Further preferably, part of the multiple Venturi channels are provided with the flap, and the wind pressure sampling nozzle extends into the Venturi channel without the flap.

[0015] Furthermore, the size of the Venturi channel without the flap is smaller than the size of the Venturi channel with the flap.

[0016] A second aspect of the present invention provides a gas water heater, which includes the above-mentioned premixer.

[0017] Furthermore, a gas pressure nozzle is provided on the gas chamber, and a wind pressure nozzle is provided on the Venturi channel.

[0018] Furthermore, the gas pressure taking nozzle is connected to a pressure sensor, and the wind pressure taking nozzle is connected to a wind pressure sensor.

[0019] A third aspect of the present invention provides a wind pressure protection method for a gas water heater, wherein the gas water heater is provided with the above-mentioned premixer, and the wind pressure protection method comprises:

[0020] (1) Obtaining gas secondary pressure SP and wind pressure FP;

[0021] (2) Determine whether to alarm and the alarm signal to be used according to the working conditions.

[0022] a. Determine the alarm signal and send an alarm in the following way:

[0023] When the wind pressure FP is lower than its lower limit g min (n) or higher than its upper limit g max (n), a wind pressure fault is reported; or

[0024] When the secondary pressure SP of the gas is lower than its lower limit value f min (n) or above its upper limit f max (n), reporting secondary pressure failure;

[0025] b. When the wind pressure FP is at its lower limit g min (n) and the upper limit g max (n), and the secondary pressure SP of the gas is at its lower limit value f min (n) and the upper limit f max (n) No alarm will be sounded.

[0026] Furthermore, the following method is used to determine the alarm signal and alarm: when the wind pressure FP is lower than its lower limit value g min (n) or higher than its upper limit g max (n), and at the same time the secondary pressure SP of the fuel gas is lower than its lower limit value f min (n) or above its upper limit f max (n), a wind pressure protection fault is reported.

[0027] A fourth aspect of the present invention provides a minimum load protection method for a gas water heater, wherein the gas water heater is provided with the above-mentioned premixer, and the minimum load protection method comprises:

[0028] When the external wind speed increases, the fan speed n of the gas water heater is increased so that the gas secondary pressure SP and the wind pressure FP reach the preset gas secondary pressure SP0 and wind pressure FP0.

[0029] Among them, SP0 is the secondary pressure of gas when the gas water heater is burning normally when the external wind speed is 0, and FP0 is the wind pressure when the gas water heater is burning normally when the external wind speed is 0.

[0030] Furthermore, if the external wind speed increases to a level that the gas secondary pressure SP and the wind pressure FP cannot reach the preset gas secondary pressure SP0 and the wind pressure FP0 even if the fan speed n is increased, the gas secondary pressure SP is reduced to the minimum gas secondary pressure SP0. min Or the wind pressure FP drops to the minimum wind pressure FP min When the fan speed n is not increased, the wind pressure FP drops below the wind pressure protection value g corresponding to the fan speed n. min (n), the whole machine stops running and reports a wind pressure fault.

[0031] Through the above technical solution, the present invention achieves the following beneficial effects:

[0032] 1. The air flow channel and the gas flow channel of the premixer of the present invention are separated and then merged, so that the air and gas can be premixed for the first time in the premixer, and the structure of the air flow channel and the Venturi channel increases the wind pressure, so that the air has a strong ability to induce the gas; in addition, a flap driven by wind is provided at the outlet of the Venturi channel, which is convenient for obtaining a wide range of load ratios to meet water demand;

[0033] 2. In the preferred technical solution of the present invention, a boss capable of blocking the outlet of the Venturi channel is provided on the flap to ensure the closing effect of the Venturi channel, thereby ensuring a small-load combustion condition and avoiding the deterioration of the exhaust gas caused by high gas and low oxygen content, or even flashback;

[0034] 3. In the preferred technical solution of the present invention, a gas pressure nozzle is provided on the gas chamber of the premixer. By reading the gas front pressure, the heat load can be calculated. At the same time, it can be used to detect the gas pressure during debugging and after-sales maintenance to analyze whether it is abnormal; a wind pressure nozzle is provided on the normally open Venturi channel, which can obtain the air pressure in the full load section so as to perform wind pressure protection when the wind pressure is abnormal;

[0035] 4. The present invention obtains the upper and lower limits of the gas secondary pressure and wind pressure by analyzing the relationship between the heat load, heat output, gas secondary pressure, wind pressure and fan speed of the gas water heater, and then determines the fault type by comparing the measured values ​​of the gas secondary pressure and wind pressure with their respective upper and lower limits, and protects or alarms the whole machine;

[0036] 5. The present invention also provides a protection mechanism in a low-load state, so that the gas water heater has a certain wind resistance performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram of a premixer described in an embodiment of the present invention;

[0038] Figure 2 yes Figure 1 A top view of

[0039] Figure 3 yes Figure 1 Bottom view of

[0040] Figure 4 yes Figure 2 Transverse cross-section of

[0041] Figure 5 yes Figure 2 Longitudinal section of

[0042] Figure 6 yes Figure 5 Schematic diagram of the nozzle and flap is omitted;

[0043] Figure 7 is a schematic structural diagram of a flap described in one embodiment of the present invention;

[0044] Figure 8 yes Figure 7 Left view of

[0045] Fig. 9 yes Figure 7 Rear view of

[0046] Fig.10 yes Figure 7 A top view of

[0047] Fig.11 is a schematic structural diagram of a flap described in another embodiment of the present invention;

[0048] Fig.12 yes Fig.11 Left view of

[0049] Fig.13 yes Fig.11 Rear view of

[0050] Fig.14 yes Fig.11 A top view of

[0051] Fig.15 It is a structural schematic diagram of the gas water heater described in the present invention;

[0052] Fig.16 It is a curve showing the relationship between heat load and fan speed obtained by fitting a gas water heater of a certain model of the present invention;

[0053] Fig.17 It is a curve showing the relationship between heat output and fan speed obtained by fitting a gas water heater of a certain model of the present invention;

[0054] Fig.18 It is a relationship curve between the secondary pressure of gas and the speed of the fan obtained by fitting a gas water heater of a certain model of the present invention;

[0055] Fig.19 It is a relationship curve between wind pressure and fan speed obtained by fitting a certain model of a gas water heater of the present invention.

[0056] Description of Reference Numerals

[0057] 1 gas chamber, 11 gas pressure taking nozzle, 2 air chamber, 3 premixing chamber, 4 gas channel, 41 nozzle, 5 flap, 51 boss, 52 rotating shaft, 6 premixer seat, 61 mounting hole, 71 air inlet seat, 72 wind pressure sensor, 73 wind pressure taking pipe, 74 bottom shell, 75 heat exchanger, 76 water collecting tray, 77 water seal, 78 smoke exhaust channel, 79 gas valve, 710 air inlet pipe, 711 burner, 712 controller, 8 Venturi channel, 81 wind pressure taking nozzle. DETAILED DESCRIPTION

[0058] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0059] First of all, it should be noted that in the following description, some directional words, such as "outside", "inside", "upper", "lower", etc., are used to clearly explain the technical solution of the present invention. They are all analogous to the normal directions of the components in the premixer and the premixer when applied to the gas water heater. For example, the part where the gas passes is the inside, and the part opposite to it is the outside. After the gas water heater is installed, the top is the top and the bottom is the bottom. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0060] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] like Figure 1-Figure 6 As shown, the premixer of the present invention includes a gas chamber 1, an air chamber 2 and a premixing chamber 3. The gas chamber 1 transports gas through one or more gas channels 4, and the air chamber 2 transports air through a Venturi channel 8 corresponding to the gas channel 4. The gas channel 4 is located in the Venturi channel 8, so that the air in the Venturi channel 8 can induce the gas in the gas channel 4 and enter the premixing chamber 3 for premixing; at least one Venturi channel 8 is provided with a flap 5 that can cover the outlet of the Venturi channel 8, and the flap 5 can separate the Venturi channel 8 and the premixing chamber 3, and can be flipped by wind force to allow the gas and air to enter the premixing chamber 3 for mixing.

[0062] The above-mentioned premixer is installed on the fan. When the fan is running, negative pressure is formed in the Venturi channel 8, so that the gas enters the gas chamber 1 from the gas inlet and then enters the gas channel 4, and the air enters the air chamber 2 from the air inlet and then enters the Venturi channel 4, generating a larger flow rate, and the gas in the gas channel 4 is ejected from the Venturi channel 8, and then the first premixing is performed in the premixing chamber 3.

[0063] In the natural state, the flap 5 closes the Venturi channel 8 where it is located, and gradually opens under the suction force of the fan, so that the Venturi channel 8 where it is located is opened. At the maximum load, the flap 5 is fully opened. When other factors such as the type of gas and the gas pressure are determined, the opening degree of the flap 5 determines the size of different loads, so that the user can obtain a wide range of hot water needs. The flap 5 is installed on the premixer seat 6 through the rotating shaft 52.

[0064] like Figure 7-Figure 14 As shown, the flap 5 is provided with a boss 51 capable of blocking the outlet of the Venturi channel 8, and the boss 51 is a cylinder or an inclined cylinder. When the flap 5 closes the corresponding Venturi channel 8, the boss 51 blocks the outlet of the Venturi channel 8 to ensure the closing effect of the flap 5, thereby ensuring the combustion condition of small load, avoiding the exhaust gas deterioration caused by high gas and low oxygen content, or even flashback.

[0065] In order to obtain a larger gas pressure and flow rate, a nozzle 41 is provided in the gas channel 4, the injection direction of which points to the premixing chamber 3. A sealing ring is installed at the connection between the nozzle 41 and the gas channel 4 to ensure that the gas does not leak out.

[0066] In order to ensure smooth and unobstructed air flow, both the concave and convex corners of the air cavity 2 need to be rounded, and the bottom of the air cavity 2 is formed as a guide inclined plate portion capable of guiding air, such as Figure 4 As shown, the concave angle γ of the air cavity 2 must be greater than 90° and less than 180°. The side wall heights L1 and L2 of the air cavity 2 must ensure that the air flow path is smooth and unobstructed during the process of air entering the air cavity 2 from the inlet and then flowing out of the air cavity 2 from the outlet.

[0067] The gas enters the gas chamber 1 from the gas inlet, and a gas pressure nozzle 11 extends from the side wall of the gas chamber 1. The gas pressure, i.e., the gas front pressure of the nozzle (i.e., the gas secondary pressure SP), can be read here using a U-tube or a micromanometer. By obtaining the gas front pressure, the heat load at this time can be calculated, and it can also be used to detect the gas pressure during debugging and after-sales maintenance to analyze whether it is abnormal.

[0068] The venturi channel 8 is provided with a wind pressure nozzle 81. Since the venturi channel 8 without the flap 5 is normally open, the pressure-taking end of the wind pressure nozzle 81 is inserted therein, and the air pressure can be obtained in the full load section. In addition, since the cross-sectional area of ​​the air decreases after entering the venturi channel 8 from the air cavity 2, the air pressure obtained here is relatively large. Even under a small load state, the obtained air pressure can meet the judgment of the wind pressure program, so that wind pressure protection is performed when the wind pressure is abnormal. Therefore, the diameter of the venturi channel 8 without the flap 5 can be set to be smaller than the diameter of the venturi channel 8 with the flap 5 to meet the needs of small load combustion.

[0069] A second aspect of the present invention provides a gas water heater, such as Fig.15 As shown, the gas water heater includes a bottom shell 74, and a fan, a heat exchanger 75, a water collecting tray 76, a water seal 77, a gas valve 79, a controller 712, a burner 711, an air inlet pipe 710, a smoke exhaust channel 78 and the above-mentioned premixer arranged in the bottom shell 74. A gas pressure nozzle 11 is provided on the gas chamber 1 of the premixer, and a wind pressure nozzle 81 is provided on the venturi channel 8. Correspondingly, a pressure sensor is connected to the gas pressure nozzle 11, and a wind pressure sensor 72 is connected to the wind pressure nozzle 81 through a wind pressure pipe 73. An air inlet seat 71 connected to the air inlet pipe 710 and a smoke exhaust seat connected to the smoke exhaust channel 78 are provided on the upper sealing plate of the bottom shell 74.

[0070] When the gas water heater is working, air enters the interior of the whole machine from the air inlet seat 71, then enters the premixer from the air inlet pipe 710, then enters the fan for mixing, and participates in combustion inside the burner 711.

[0071] Based on the above technical solution, the present invention also provides a wind pressure protection method for a gas water heater, the wind pressure protection method comprising:

[0072] Obtain the secondary gas pressure SP and wind pressure FP, and then compare the secondary gas pressure SP and wind pressure FP with their corresponding upper and lower limits to determine the fault type and protect or alarm the whole machine. For example, the following methods can be used to determine the alarm signal and alarm:

[0073] When the wind pressure FP is lower than its lower limit g min (n) or higher than its upper limit g max (n), a wind pressure fault is reported; or when the secondary gas pressure SP is lower than its lower limit value f min (n) or above its upper limit f max (n), reporting secondary pressure failure. Specifically, it can be divided into the following modes:

[0074] Mode 1: As long as the wind pressure FP is lower than its lower limit g min (n) or higher than its upper limit g max (n), the wind pressure fault is reported; and when the gas secondary pressure SP is lower than its lower limit f min (n) or above its upper limit f max (n), and the wind pressure FP is at its lower limit g min (n) and the upper limit g max (n) between, secondary pressure fault is reported;

[0075] Mode 2: As long as the secondary pressure SP of the gas is lower than its lower limit f min (n) or above its upper limit f max (n), a secondary pressure fault is reported; and when the wind pressure FP is lower than its lower limit g min (n) or higher than its upper limit g max (n), and the secondary pressure SP of the fuel gas is at its lower limit value f min (n) and the upper limit f max (n) between, the wind pressure fault is reported;

[0076] Furthermore, mode 3 may be included: when the wind pressure FP is lower than its lower limit g min (n) or higher than its upper limit g max (n), and the secondary pressure SP of the gas is lower than its lower limit f min (n) or above its upper limit f max (n), the wind pressure protection fault is reported; when the wind pressure FP is lower than its lower limit g min (n) or higher than its upper limit g max (n), and the secondary pressure SP of the fuel gas is at its lower limit value f min (n) and the upper limit f max (n), a wind pressure fault is reported; when the secondary gas pressure SP is lower than its lower limit f min (n) or above its upper limit f max(n), and the wind pressure FP is at its lower limit g min (n) and the upper limit g max (n) between, secondary pressure fault is reported.

[0077] When the wind pressure FP is at its lower limit g min (n) and the upper limit g max (n), and the secondary pressure SP of the gas is at its lower limit value f min (n) and the upper limit f max (n) No alarm will be sounded.

[0078] As described above, the comparison between the gas secondary pressure SP and the wind pressure FP is performed in the controller 712, and the fault type is displayed on the display.

[0079] For example, you can use g min (n) is set as the wind pressure protection value. When the smoke pipe is blocked, the wind pressure FP corresponding to the fan speed n of the whole machine drops to a level lower than the wind pressure protection value g corresponding to the speed. min (n), the controller 712 outputs a signal to close the gas valve 79, the whole machine stops running, and reports a wind pressure fault on the display. This can protect the whole machine from burning normally, avoid the generation of excess exhaust gas during combustion, and also prevent the water seal from being blown open, preventing the smoke from being discharged into the room through the water seal.

[0080] When the wind speed increases, the wind pressure FP corresponding to the fan speed n of the whole machine decreases and drops to a level lower than the wind pressure protection value g corresponding to the speed. min (n), the controller 712 outputs a signal to close the gas valve 79, the whole machine stops running, and reports a wind pressure fault on the display. This can protect the whole machine from burning normally, avoid the generation of excess exhaust gas during combustion, and also prevent the water seal from being blown open, preventing the smoke from being discharged into the room through the water seal.

[0081] When the water seal is blocked, the wind pressure FP corresponding to the fan speed n of the whole machine drops to a level lower than the wind pressure protection value g corresponding to the speed. min (n), the controller 712 outputs a signal to close the gas valve 79, the whole machine stops running, and reports a wind pressure fault on the display. This can protect the whole machine from burning normally and avoid generating excess exhaust gas during combustion.

[0082] The wind pressure protection of water seal, blockage and blowing will be carried out when any wind pressure reaches the wind pressure protection condition.

[0083] As described above, the secondary gas pressure SP and the wind pressure FP are obtained by the pressure sensor and the wind pressure sensor 72 respectively, and the lower limit value f of the secondary gas pressure SP is min (n) and the upper limit f max(n) and the lower limit value g of the wind pressure FP min (n) and the upper limit g max The method for obtaining (n) is:

[0084] 1) The heat load W (or heat output Q) corresponds to the fan speed n. During the design, the basic data of the heat load W (or heat output Q) and the fan speed n of multiple prototypes are first collected, and the curves of the two are fitted. Through linear regression, the corresponding relationship between the two is obtained: W = f1 (n) or Q = f2 (n). The heat load W (or heat output Q) is obtained by calculation: the water inlet temperature T0, water flow q and water outlet temperature T0 on multiple prototypes are obtained respectively. t , according to Q = q*(T t -T0) calculates the heat output Q, and then calculates the heat load W according to the thermal efficiency η; the inlet water temperature T0 is measured by the inlet water temperature sensor, the water flow rate q is measured by the inlet water flow rate sensor, and the outlet water temperature T t It is measured by the outlet water temperature sensor; for example, the heat load W and heat output Q of a certain model of water heater at each fan speed n are calculated, and the results are shown in Table 1. The relationship curve between heat load and fan speed is obtained by Excel fitting regression as shown in Fig.16 As shown, the corresponding formula is W = 0.0079n-3.0627, and the relationship curve between heat output and fan speed is as follows Fig.17 As shown, the corresponding formula is Q = 0.0085n-3.3077, and the goodness of fit of the two curves (R 2 ) are 0.9978 and 0.9978 respectively, and the regression line fits the observed values ​​well.

[0085] Table 1 Fan speed, heat output, heat load, gas secondary pressure and wind pressure

[0086]

[0087]

[0088] 2) As the fan speed increases, the gas secondary pressure SP and wind pressure FP will also increase accordingly. Therefore, there is a one-to-one correspondence between the fan speed n and the gas secondary pressure SP, and there is also a one-to-one correspondence between the fan speed n and the wind pressure FP. During the design, first obtain the basic data of the fan speed n, gas secondary pressure SP and wind pressure FP of multiple prototypes, fit the curves of the two, and through linear regression, obtain the corresponding relationship between the gas secondary pressure SP and wind pressure FP and the fan speed n: SP = f(n) and FP = g(n). For example, the gas secondary pressure SP and wind pressure FP of a certain model of water heater are measured at each fan speed n. The results are shown in Table 1. The relationship curve between the gas secondary pressure and the fan speed is obtained by Excel fitting regression as shown in Table 1. Fig.18As shown, the corresponding formula is SP = 0.0323n-64.129, and the relationship curve between wind pressure and fan speed is as follows Fig.19 As shown, the corresponding formula is FP = 0.1997n-242.84, and the goodness of fit of the two curves (R 2 ) are 0.9624 and 0.9731 respectively, and the regression lines fit the observed values ​​well.

[0089] 3) Obtain the basic data of heat load W, heat output Q, fan speed n, gas secondary pressure SP and wind pressure FP of multiple prototypes, and then calculate the water inlet temperature T0, water flow rate q and water outlet temperature T0 according to the running of the prototypes. t The range of heat output Q or heat load W is calculated, and then the range of fan speed n is determined according to the basic data of heat load W, heat output Q, fan speed n, gas secondary pressure SP and wind pressure FP and the corresponding relationship between heat load W or heat output Q and fan speed n W = f1(n) or Q = f2(n). Then, according to the range of fan speed n, the range of gas secondary pressure SP and wind pressure FP is determined, and finally the lower limit value f of secondary pressure SP is obtained. min (n) and the upper limit f max (n) and the lower limit value g of the wind pressure FP min (n) and the upper limit g max (n).

[0090] On the other hand, if the premixer is provided with multiple Venturi channels 8, the flap 5 is closed when the minimum load state is reached. Since the fan speed n is very small in the minimum load state, the secondary pressure SP and the wind pressure FP are also very small. At this time, when the external wind speed is high, it is easy to blow out the flame, so the minimum gas secondary pressure SP is set. min and minimum wind pressure FP min Based on this, the present invention also provides a minimum load protection method for a gas water heater, and the minimum load protection method is:

[0091] When the gas water heater is burning in the small load section, if the external wind speed is 0, the secondary pressure of the gas water heater during normal combustion is SP0, and the wind pressure is FP0. At this time, the combustion state is optimal.

[0092] When the external wind speed increases, the secondary gas pressure SP and wind pressure FP during the small load stage combustion will decrease. Once the secondary gas pressure SP and wind pressure FP decrease, the controller 712 will analyze and process, and increase the fan speed n of the gas water heater, so that the secondary gas pressure SP and wind pressure FP are restored to the preset secondary gas pressure SP0 and wind pressure FP0, so as to maintain normal combustion and make the gas water heater (wall-mounted boiler) have a certain wind resistance performance;

[0093] If the external wind speed increases to the point where even if the fan speed n is increased, the gas secondary pressure SP and the wind pressure FP cannot reach the preset gas secondary pressure SP0 and wind pressure FP0, such as when the external wind speed increases suddenly or increases too much, the fan speed n cannot be increased in time or exceeds the range of the fan speed n, and the gas secondary pressure SP drops to the minimum gas secondary pressure SP min Or the wind pressure FP drops to the minimum wind pressure FP min When the fan speed n is not increased, the wind pressure FP drops below the wind pressure protection value g corresponding to the fan speed n. min (n), the gas valve 79 is closed, the whole machine stops running, and a wind pressure fault is reported.

[0094] Based on this, the minimum gas secondary pressure SP min and wind pressure FP min The value can be used to adjust the wind resistance of the whole machine.

[0095] The following is a preferred embodiment of the premixer of the present invention.

[0096] like Figure 1-Figure 6 As shown, the premixer of the present invention comprises a gas chamber 1, an air chamber 2 and a premixing chamber 3. The gas chamber 1 conveys gas through two gas channels 4, and the air chamber 2 conveys air through two venturi channels 8 corresponding to the gas channels 4. A gas channel 4 is arranged in a venturi channel 8, and a nozzle 41 is arranged on each gas channel 4. The diameters of the two nozzles 41 are different. The venturi channel 8 corresponding to the nozzle 41 with a large diameter is large in size, and a flap 5 capable of covering the outlet of the venturi channel 8 is arranged at the outlet. The flap 5 can separate the venturi channel 8 and the premixing chamber 3, and can be turned over by wind force so that the gas and air enter the premixing chamber 3 for mixing. The flap 5 is provided with a boss 51 capable of blocking the outlet of the venturi channel 8. A gas pressure nozzle 11 is arranged on the gas chamber 1, and a wind pressure nozzle 81 is arranged on the venturi channel 8 corresponding to the nozzle 41 with a small diameter.

[0097] When the premixer is in use, it is installed at the inlet of the fan of the gas water heater through the mounting hole 61 on the premixer seat 6, with the pressure-taking end of the wind pressure nozzle 81 facing upwards, and the pressure-taking end of the gas pressure nozzle 11 facing downwards. In the natural state, the flap 5 droops under the action of gravity, closing the Venturi channel 8 corresponding to the large nozzle 41. When the load is small, the air volume of the fan is small, and the flap 5 closes the Venturi channel 8 corresponding to the nozzle 41 with a larger diameter, so that all the gas flows out from the Venturi channel 8 corresponding to the nozzle 41 with a smaller diameter; as the air volume increases, the flap 5 gradually flips up under the suction force of the wind, opens the Venturi channel 8 corresponding to the larger nozzle 41, and makes the gas flow out from the two Venturi channels 8 at the same time; when the load is maximum, the flap 5 is fully opened. When other factors such as the type of gas, gas pressure, and the diameter of the nozzle 41 are determined, the opening degree of the flap 5 determines the size of different loads. The load regulation ratio of the whole machine is determined by the large nozzle diameter d1 and the small nozzle diameter d2. When (d1 2 +d2 2 ) / d2 2 When it is greater than 5, the adjustment ratio is greater than 10:1.

[0098] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0099] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0100] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A premixer, characterized in that: The invention comprises a gas chamber (1), an air chamber (2) and a premixing chamber (3); the gas chamber (1) conveys gas through one or more gas channels (4); the air chamber (2) conveys air through a Venturi channel (8) corresponding to the gas channel (4); the gas channel (4) is located in the Venturi channel (8), so that the air in the Venturi channel (8) can induce the gas in the gas channel (4) and enter the premixing chamber (3) for premixing; the gas chamber (1) is provided with a gas pressure nozzle (11); the Venturi channel (8) is provided with a wind pressure nozzle (81); and the wind pressure nozzle (81) is connected to a wind pressure sensor (72); A flap (5) capable of covering the outlet of the Venturi channel (8) is provided on some of the multiple Venturi channels (8); the flap (5) can separate the Venturi channel (8) and the premixing chamber (3), and can be flipped by wind force so that the gas and air enter the premixing chamber (3) for mixing; the wind pressure sampling nozzle (81) extends into the Venturi channel (8) without the flap (5).

2. The premixer according to claim 1, characterized in that The flap (5) is provided with a boss (51) capable of blocking the outlet of the Venturi passage (8).

3. The premixer according to claim 2, characterized in that The boss (51) is a cylinder or a beveled cylinder.

4. The premixer according to claim 1, characterized in that The gas channel (4) is provided with a nozzle (41) whose injection direction points to the premixing chamber (3).

5. The premixer according to claim 1, characterized in that The bottom of the air cavity (2) is formed as a guide inclined plate portion capable of guiding air.

6. The premixer according to claim 1, characterized in that The size of the Venturi channel (8) without the flap (5) is smaller than the size of the Venturi channel (8) with the flap (5).

7. A gas water heater, characterized in that: Comprising a premixer according to any one of claims 1 to 5.

8. The gas water heater according to claim 7, characterized in that: The gas pressure tapping nozzle (11) is connected to a pressure sensor.

9. A wind pressure protection method for a gas water heater, characterized in that: The gas water heater is provided with a premixer according to any one of claims 1 to 6, and the wind pressure protection method comprises: (1) Obtaining gas secondary pressure SP and wind pressure FP; (2) Determine whether to alarm and the alarm signal to be used according to the working conditions. a. Determine the alarm signal and sound the alarm in the following way: When the wind pressure FP is lower than its lower limit gmin(n) or higher than its upper limit gmax(n), a wind pressure fault is reported; or When the gas secondary pressure SP is lower than its lower limit value fmin(n) or higher than its upper limit value fmax(n), a secondary pressure fault is reported; b. When the wind pressure FP is between its lower limit value gmin(n) and upper limit value gmax(n), and the gas secondary pressure SP is between its lower limit value fmin(n) and upper limit value fmax(n), no alarm is given.

10. The wind pressure protection method for a gas water heater according to claim 9, characterized in that: The alarm signal is also determined and the alarm is issued in the following manner: when the wind pressure FP is lower than its lower limit gmin(n) or higher than its upper limit gmax(n), and at the same time the gas secondary pressure SP is lower than its lower limit fmin(n) or higher than its upper limit fmax(n), a wind pressure protection fault is reported.

11. A minimum load protection method for a gas water heater, characterized in that: The gas water heater is provided with a premixer according to any one of claims 1 to 6, The minimum load protection method comprises: When the external wind speed increases, the fan speed n of the gas water heater is increased so that the gas secondary pressure SP and the wind pressure FP reach the preset gas secondary pressure SP0 and wind pressure FP0, wherein SP0 is the gas secondary pressure when the gas water heater is burning normally when the external wind speed is 0, and FP0 is the wind pressure when the gas water heater is burning normally when the external wind speed is 0.

12. The minimum load protection method for a gas water heater according to claim 11, characterized in that: in, If the external wind speed increases to the point where even if the fan speed n is increased, the gas secondary pressure SP and the wind pressure FP cannot reach the preset gas secondary pressure SP0 and the wind pressure FP0, and when the gas secondary pressure SP drops to the minimum gas secondary pressure SPmin or the wind pressure FP drops to the minimum wind pressure FPmin, the fan speed n will no longer be increased until the wind pressure FP drops below the wind pressure protection value gmin(n) corresponding to the fan speed n. The whole machine will then stop running and report a wind pressure fault.

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