A novel auxiliary control system for gas water heaters

Abstract

This utility model discloses a novel auxiliary control system for a gas water heater, comprising a DC motor and an auxiliary control board. The auxiliary control board includes an AC-to-DC unit, a DC motor control unit, and a protection switch signal output unit. The AC-to-DC unit converts the input 220V AC power into DC power to supply the DC motor control unit. The DC motor control unit controls the rotation of the DC motor and monitors its operating status. A microcontroller (MCU) drives the DC motor with constant current and performs high dynamic response closed-loop control of the motor speed. Without altering the existing structure and main control system of the AC gas water heater, simply replacing the AC motor with a DC fan, eliminating the wind pressure switch, and assembling the auxiliary control board constitutes the auxiliary control system for the gas water heater. This reduces the failure rate, improves performance stability and energy efficiency, and enhances the fan's wind pressure resistance.

Description

Technical Field

[0001] This utility model relates to the field of gas water heaters, and in particular to a novel auxiliary control system for gas water heaters. Background Technology

[0002] Currently, existing forced-draft AC gas water heaters are connected to a 220V AC power supply via a plug. A 220V / 50Hz AC motor is installed on the fan inside the water heater. When the gas water heater is working, the AC motor drives the impeller inside the fan to quickly exhaust the exhaust gases produced during combustion outdoors. For example... Figure 1 and Figure 2 As shown, a forced-draft gas water heater includes: a shell, a burner, a heat exchanger, a water-gas linkage device, an ignition device, a gas solenoid valve, a fan 11, an AC motor 12, a pressure switch 13, and a main control device 14. The main control device 14 is equipped with an AC220V power output port 141 and a switch signal input terminal 142. The AC220V power output port 141 is connected to the AC motor 12 to provide power, and the pressure signal input terminal 142 is electrically connected to the pressure switch 13.

[0003] The startup sequence of a gas water heater includes: opening the water outlet pipe → the control device detecting the water flow signal → the AC motor powering on and pre-cleaning → the pressure switch detecting the air pressure inside the fan; the normal operating state of the pressure switch is circuit continuity → the ignition device starting ignition and the gas solenoid valve opening to supply gas → the burner igniting. During the operation of the water heater, the pressure switch monitors the flue status in real time. If abnormalities such as flue blockage or backdraft occur, the circuit of the pressure switch is disconnected. After receiving the disconnection signal, the control device 14 controls the gas solenoid valve to cut off the gas supply and shut down the ignition device. The problem is that the pressure switch is a protective switch device for gas water heaters, belonging to the mechanical type. Its structure mainly consists of a plastic shell and a silicone gas film. The signal circuit is connected / disconnected by a push rod touching a micro switch. Frequent operation leads to a high failure rate and poor control accuracy of the pressure switch. Moreover, the pressure switch is installed and used inside the high-temperature water heater body, which easily causes aging of the pressure switch shell and heat and moisture damage to internal components, accelerating its aging and shortening its service life.

[0004] Furthermore, the 220V / 50HZ AC motors used in gas water heaters operate at a fixed frequency and cannot be dynamically adjusted. This results in low resistance to external wind pressure (wind resistance less than 150Pa). Additionally, their power and speed are significantly affected by fluctuations in the mains voltage, and AC motors have high input power and high energy consumption. Therefore, how to manufacture gas water heaters with low failure rates, stable performance, longer service life, and greater energy efficiency without altering the overall structure and main control system of existing AC gas water heaters is a pressing issue that needs to be addressed for AC-electric gas water heaters. Utility Model Content

[0005] The purpose of this utility model is to provide a novel auxiliary control system for gas water heaters to solve the problems mentioned in the background art. Without changing the main structure and logic control system of the existing AC gas water heater, the auxiliary control system is composed of a DC motor and an auxiliary control board to replace the existing AC motor and wind pressure switch monitoring and control method, so that the gas water heater has the characteristics of low failure rate, stable performance, longer service life and more energy saving.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A novel auxiliary control system for a gas water heater includes a DC motor and an auxiliary control board. The DC motor is mounted on a fan, and its shaft is connected to the fan wheel. The auxiliary control board is equipped with a 220V AC power input interface, a DC power output interface, and a switch signal output interface. The AC power input interface is connected to the 220V AC power output terminal on the main control device of the gas water heater, the DC power output interface is connected to the DC motor, and the switch signal output interface is connected to the switch signal input terminal on the main control device of the gas water heater.

[0008] The auxiliary control board includes an AC to DC conversion unit, a DC motor control unit, and a protection switch signal output unit;

[0009] The AC-to-DC unit converts the input 220V AC power into DC power through rectification, filtering, and transformation, and then supplies it to the DC motor control unit.

[0010] The DC motor control unit is used to control the rotation of the DC motor and monitor its operating status. A microcontroller (MCU) drives the DC motor in a constant current mode and samples the phase current of the three-phase brushless DC motor in real time. Combined with the field-oriented control (FOC) algorithm, the motor speed is accurately calculated, enabling high dynamic response closed-loop control of the motor speed. During the operation of the gas water heater, when the external wind force is too strong, backflow resistance forms in the exhaust pipe, reducing the area of ​​the fan outlet. Since the DC motor drive unit 222 operates in constant current mode, the output current remains constant, and the motor speed increases accordingly, improving the overall efficiency of the fan and enhancing its wind pressure resistance.

[0011] Specifically, the DC motor is a three-phase brushless DC motor; the AC-to-DC unit outputs a DC voltage of 0 to 36 volts.

[0012] Preferably, the AC-to-DC unit outputs a DC voltage of 24 volts.

[0013] The protection switch signal output unit includes an optocoupler.

[0014] This utility model provides a novel auxiliary control system for gas water heaters. Without altering the existing overall structure and main control system of an AC gas water heater, it only requires replacing the AC motor with a DC fan of the same specifications, eliminating the mechanical pressure switch, and installing an auxiliary control board to form an auxiliary control system. When applied to a gas water heater, this system enables the gas water heater to achieve the following effects:

[0015] 1. The DC motor on the fan is powered independently by the AC-to-DC unit on the auxiliary control board, and is not affected by fluctuations in the mains voltage. This ensures stable DC motor speed, precise airflow control for the fan, and effectively improves the performance of the gas water heater.

[0016] 2. The DC motor on the fan is driven by constant current control, which has high speed control accuracy. The auxiliary control system monitors the motor's operating status in real time and can automatically increase the speed of the DC motor to improve the fan's wind pressure resistance. The wind resistance performance can be improved by about 20%.

[0017] 3. The mechanical wind pressure switch with a high failure rate has been eliminated. By using the cooperation of a microprocessor (MCU) and an optocoupler, the switch signal output is precisely controlled, which greatly reduces the failure rate of the gas water heater and improves the safety of its use.

[0018] 4. Converting the fan's AC power to DC power reduces the overall power consumption of the gas water heater, resulting in an overall energy consumption reduction of about 15%, achieving excellent energy-saving effects.

[0019] 5. This auxiliary control board is directly connected to the main controller. The auxiliary control system is easy to install and can be directly applied to the overall structure of existing gas water heaters. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an existing AC gas water heater.

[0021] Figure 2 This is a circuit connection diagram of the main control device, AC motor, and air pressure switch of an existing AC gas water heater.

[0022] Figure 3 This is a schematic diagram of the structure of the gas water heater of this utility model.

[0023] Figure 4 This is a circuit diagram showing the connection between the main control device of the gas water heater, the DC motor, and the auxiliary control board of this utility model.

[0024] Figure 5 This is a circuit block diagram of the auxiliary control board of this utility model;

[0025] Figure 6 This is the circuit diagram of the auxiliary control board of this utility model;

[0026] Figure 7 This is a flowchart of the auxiliary control system of this utility model. Detailed Implementation

[0027] To make the technical solutions and effects of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of this utility model, and not all embodiments.

[0028] The terms "connection," "setting," and "installation" used in this utility model should be interpreted broadly. For example, "connection" can be a fixed connection, a movable connection, or a detachable connection; it can also be a mechanical connection or an electrical connection; and it can be a direct connection or an indirect connection through an intermediate medium. Unless otherwise explicitly specified and limited, those skilled in the art can understand the specific meaning of the aforementioned terms in this utility model based on the actual situation. The terms "inner," "outer," "front," "rear," "upper," "lower," "left," and "right," etc., describe the orientation or positional relationship of the device / component indicated in the drawings, and do not emphasize that the indicated component / device must have a specific orientation structure and operation, and should not be construed as a limitation on the scope of protection of this utility model. The terms "first," "second," and "third," etc., are only used to distinguish similar technical features, and should not be construed as indicating the relative importance or sequential relationship of the technical features.

[0029] like Figure 3 , Figure 4 and Figure 5 As shown, a novel auxiliary control system for a gas water heater includes a DC motor 21 and an auxiliary control board 22. The DC motor 21 is mounted on a fan, and the shaft of the DC motor 21 is connected to the fan wheel. The auxiliary control board 22 is provided with a 220V AC power input interface 221, a DC power output interface 222, and a switch signal output interface 223. The AC power input interface 221 is connected to the 220V AC power output terminal on the main control device 14 of the gas water heater, the DC power output interface 222 is connected to the DC motor 21, and the switch signal output interface 223 is connected to the switch signal input terminal on the main control device 14 of the gas water heater.

[0030] The auxiliary control board 22 includes an AC to DC conversion unit 31, a DC motor control unit 32, and a protection switch signal output unit 33;

[0031] The AC-to-DC unit 31 converts the input 220V AC power into 0-36V DC power after rectification, filtering and transformation, and then supplies it to the DC motor control unit 32.

[0032] The DC motor control unit 32 is used to control the rotation of the DC motor and monitor its operating status. The microcontroller (MCU) drives the DC motor in a constant current mode and samples the phase current of the three-phase brushless DC motor in real time. Combined with the field-oriented control (FOC) algorithm, the motor speed is accurately calculated, achieving high dynamic response closed-loop control of the motor speed. During the operation of the gas water heater, when the external wind force is too strong, backflow resistance forms in the exhaust pipe, reducing the area of ​​the fan outlet. Since the DC motor drive unit 222 operates in constant current mode, the output current remains constant, and the motor speed increases accordingly, improving the overall efficiency of the fan and enhancing its wind pressure resistance.

[0033] The protection switch signal output unit 33 includes an optocoupler. By utilizing the electrical isolation characteristics, strong anti-interference ability, and fast switch response speed of the optocoupler, the precise control of the safety protection of the gas water heater is effectively improved, and the failure rate of switch signal distortion is reduced.

[0034] like Figure 7 As shown, when the DC motor control unit 32 detects that the DC motor speed reaches the set protection value, the DC motor speed is lower than 1200 r / min during combustion, or the fan suddenly stops, the DC motor control unit program determines that it is abnormal and sends an execution disconnect command to the protection switch signal output unit. The protection switch signal output unit sends a disconnection electrical signal to the main control device of the gas water heater. The main control device's solenoid valve cuts off the gas supply and shuts off the ignition device, and the gas water heater stops combustion.

[0035] Although the embodiments of this utility model have shown the technical solutions, those skilled in the art can understand that the technical solutions proposed by replacing, modifying or altering these embodiments in combination with conventional technology without departing from the principles and structure of this utility model are substantially the same as those of this utility model.

Claims

1. A novel auxiliary control system for gas water heaters, characterized by: It includes a DC motor and an auxiliary control board; the DC motor is mounted on a fan, and the shaft of the DC motor is connected to the fan wheel; the auxiliary control board is provided with a 220V AC power input interface, a DC power output interface, and a switch signal output interface. The AC power input interface is connected to the 220V AC power output terminal on the main control device of the gas water heater, the DC power output interface is connected to the DC motor, and the switch signal output interface is connected to the switch signal input terminal on the main control device of the gas water heater.

2. The novel auxiliary control system for a gas water heater according to claim 1, characterized in that: The auxiliary control board includes an AC to DC conversion unit, a DC motor control unit, and a protection switch signal output unit; The AC-to-DC unit converts the input 220V AC power into DC power through rectification, filtering, and transformation, and then supplies it to the DC motor control unit. The DC motor control unit is used to control the rotation of the DC motor and monitor its operating status.

3. The novel auxiliary control system for a gas water heater according to claim 2, characterized in that: The DC motor control unit is driven by a microcontroller (MCU) in a constant current manner to drive the DC motor.

4. A novel auxiliary control system for a gas water heater according to claim 3, characterized in that: The DC motor control unit samples the phase current of the brushless DC motor in real time, and combines it with the field-oriented control (FOC) algorithm to accurately calculate the motor speed, thereby performing closed-loop control of the motor speed with high dynamic response.

5. A novel auxiliary control system for a gas water heater according to claim 4, characterized in that: The DC motor is a three-phase brushless DC motor.

6. A novel auxiliary control system for a gas water heater according to claim 5, characterized in that: The AC-to-DC unit outputs a DC voltage of 0 to 36 volts.

7. A novel auxiliary control system for a gas water heater according to claim 6, characterized in that: The AC-to-DC unit outputs a DC voltage of 24 volts.

8. A novel auxiliary control system for a gas water heater according to any one of claims 2-7, characterized in that: The protection switch signal output unit includes an optocoupler.

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