Control method of drainage pump and drainage pump

Abstract

The invention provides a control method of a drainage pump and the drainage pump, and the control method comprises the steps: adjusting the rotating speed of a motor of the drainage pump in a low-torque working state smaller than or equal to a preset torque to a preset range, and enabling the rotating speed of the motor corresponding to the preset range to be lower than the rotating speed corresponding to a normal characteristic curve of an existing motor; according to the control method, the rotating speed of the motor under the low torque can be reduced, and then the purpose of reducing noise is achieved. Meanwhile, certain energy-saving capacity is achieved by reducing the rotating speed, namely, the rotating speed is reduced under low torque, and a part of input power can be reduced to achieve energy conservation; in addition, the temperature rise can be reduced by reducing the rotating speed, and the product reliability is improved. And in a low-load working area including no-load operation, the rotating speed is controlled within a preset range, so that the operation noise is effectively reduced, and the comfort of the product in the use process is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fluid control, and in particular to a control method for a drainage pump and a drainage pump. Background Art

[0002] Drain pumps are a type of drainage equipment widely used in various fields of production and life. For example, the indoor unit of a ceiling-mounted air conditioner is equipped with a drain pump. During the operation of the air conditioner, a large amount of condensed water will be generated on the surface of the heat exchanger due to the cooling of the air. When the water accumulates to a certain extent, it will drip into the condensed water tank under the heat exchanger. The condensed water in the water tray is discharged to the outside through the drain pump.

[0003] Usually, depending on the application requirements, the drain pump needs to have a certain flow rate and head to meet the condensate discharge needs, and due to the noise requirements of the use environment, the working noise of the drain pump must also be limited to a certain range.

[0004] How to reduce the working noise of the drainage pump as much as possible is an issue that technicians in this field always pay attention to. Summary of the invention

[0005] The object of the present invention is to provide a control method for a drainage pump and a drainage pump with relatively low working noise.

[0006] The present invention provides a control method for a drainage pump, wherein the drainage pump comprises a motor, and the control method comprises:

[0007] Acquisition step: acquiring the working torque of the drainage pump in the current working condition according to the current load parameters, wherein the load parameters include one or more of the water level, the head, and the liquid viscosity;

[0008] Adjustment step: judging the magnitude of the working torque under the current working condition and the pre-stored preset torque, and when the working torque of the drainage pump is less than or equal to the preset torque, controlling the motor speed clock of the drainage pump to be maintained within a preset range;

[0009] The preset torque is equal to or less than the maximum working torque of the drainage pump, the motor speed corresponding to the maximum working torque of the drainage pump is defined as a first speed, and the maximum value of the preset range is equal to or less than 1.1 times of the first speed.

[0010] In addition, the present invention also provides a drainage pump, including a motor part, a pump body part and a chip, the motor part includes a motor, and the chip is integrated with a control method of the drainage pump.

[0011] In the control method of the present invention, the motor speed of the drainage pump in a low-torque working state (including no-load operation) less than or equal to the preset torque is adjusted to a preset range, and the maximum value of the preset range is equal to or less than 1.1 times the motor speed corresponding to the maximum working torque of the drainage pump, that is, the maximum value of the motor speed corresponding to the low-torque working state is lower than the speed corresponding to the normal characteristic curve of the existing motor, that is, the control method of the present invention can reduce the motor speed under low torque, thereby achieving the purpose of reducing noise. At the same time, a certain energy-saving ability is achieved by reducing the speed, that is, the speed reduction under low torque can reduce a part of the input power to achieve energy saving. In addition, reducing the speed can also reduce temperature rise and improve product reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the mechanical performance curve of the motor in the prior art;

[0013] Figure 2 A schematic diagram of the structure of a drainage pump in an embodiment of the present invention;

[0014] Figure 3 A flow chart of a method for controlling a drainage pump in one embodiment of the present invention;

[0015] Figure 4 A schematic diagram of a motor working curve in an embodiment of the present invention;

[0016] Figure 5 The figure is a flow chart of a method for controlling a drainage pump in another embodiment of the present invention.

[0017] in, Figure 2 The one-to-one correspondence between the reference numerals and the component names is as follows:

[0018] 100 motor part; 101 motor housing; 200 pump body part; 201 housing; 202 impeller; 203 suction port; 204 discharge port; 300 water receiving tray. DETAILED DESCRIPTION

[0019] In view of the technical problem of how to reduce the working noise of the drainage pump mentioned in the background technology, the present invention has conducted an in-depth study on the drainage pump, and found that the current method of reducing the working noise of the drainage pump is mainly to improve the structure of the drainage pump, such as by improving the impeller structure in the drainage pump, or how to ensure that the impeller rotating shaft is coaxial with the motor shaft, etc. The current structural optimization space is getting smaller and smaller, and the space for reducing working noise is also becoming more and more limited.

[0020] The inventor of the present invention also found that when the current drainage pump is in operation, the working noise of the drainage pump at low head and low water level is significantly greater than the noise in other working states. Figure 1The motor mechanical performance curve is shown in the figure. Figure 1 Two curves are given. Curve S1 is the mechanical characteristic curve of the motor under 12V voltage, and curve S2 is the mechanical characteristic curve of the motor under 11.5V voltage. The horizontal axis represents torque and the vertical axis represents speed. When the drainage pump motor is running, the motor speed decreases as the load torque increases. When the motor torque is small, the speed is high, so the working noise is relatively large.

[0021] In the traditional design method, the motor speed is not limited, that is, the speed is higher at low torque, such as Figure 1 As shown. In actual installation in different application scenarios, different installations make the drainage pump have different heads. When the drainage pump is designed, the drainage pump can meet the flow and head requirements under the maximum working condition. This leads to the phenomenon that when this type of drainage pump is used below the maximum head, the output power is excessive, resulting in excessive noise and other phenomena.

[0022] On the other hand, when the air conditioner is in use, a certain space (the distance is greater than 8mm) must be reserved between the drain pump and the sink. Figure 2 As shown in the figure, the water in this distance cannot be drained out. During long-term operation, the condensed water in the water tank will become dirty due to the entry of impurities, bacterial growth, and residual bacterial excrement, which will cause the viscosity of the condensed water in the water tank to increase. At this time, the torque required by the drainage pump will increase, resulting in a decrease in motor speed and a decrease in flow.

[0023] The inventor of the present invention has proposed a control method that can further reduce the working noise of a drainage pump through a large number of experiments and explorations, and a drainage pump having the control method. The implementation scheme under the present invention mainly includes increasing the motor speed within the specified working torque range to adapt to the increase in torque without causing the flow rate of the drainage pump to decrease.

[0024] In order to enable those skilled in the art to better understand the technical solutions of the embodiments of the present application, the embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the objectives, technical solutions and advantages of the present application more clear, the present application is further described in detail below in conjunction with the drawings and specific embodiments.

[0026] Please refer to Figures 2 to 5 , Figure 2 A schematic diagram of the structure of a drainage pump in an embodiment of the present invention; Figure 3 A flow chart of a method for controlling a drainage pump in one embodiment of the present invention; Figure 4 A schematic diagram of a motor working curve in an embodiment of the present invention; Figure 5The figure is a flow chart of a method for controlling a drainage pump in another embodiment of the present invention.

[0027] The drainage pump provided in the embodiment of the present invention includes a motor part 100 and a pump body part 200. The pump body part 200 has a housing 201 of a pump chamber, an impeller 202 is arranged inside the pump chamber, and the housing 201 has a suction port and a discharge port connected to the pump chamber. The motor part 100 includes a motor housing 101, and the motor housing 101 has a stator, a rotor, a motor shaft and other motor components. The motor shaft passes through the motor housing 101 and can be connected to the impeller 202. When the drainage pump is started, the motor shaft drives the impeller 202 to rotate. The rotation of the impeller 202 can suck water from the external environment such as the water receiving tray 300 into the pump chamber from the suction port 203 of the housing 201, and then discharge it through the discharge port 204. The motor part 100 can be a brushless motor.

[0028] An embodiment of the present invention provides a control method for a drainage pump, the control method comprising:

[0029] S0 acquisition step: obtaining the working torque of the drainage pump in the current working condition according to the current load parameters, the load parameters include one or more of the water level, the head, and the liquid viscosity. Of course, the load parameters are not limited to the above-mentioned ones, and can also be other parameters related to the load;

[0030] The working torque of the drainage pump can be directly read from the control unit of the drainage pump. The control unit can be a chip, that is, the control unit can be a microcontroller unit (MCU), which has peripheral interfaces such as a central processing unit (CPU), memory, counter (Timer), USB, A / D conversion, universal asynchronous receiver / transmitter (UART), programmable logic controller (PLC), direct memory access (DMA), and even LCD driving circuits are integrated on a single chip to form a chip-level computer.

[0031] The working torque is directly obtained from the control unit, so no sensor or feedback signal is required.

[0032] S1 adjustment step: determine the working torque under the current working condition and the pre-stored preset torque. When the working torque under the current working condition is less than or equal to the preset torque, control the motor speed of the drainage pump to always maintain within the preset range.

[0033] The preset torque is equal to or less than the maximum working torque of the drainage pump, the motor speed corresponding to the maximum working torque of the drainage pump is defined as the first speed, and the maximum value of the preset range is equal to or less than 1.1 times of the first speed.

[0034] In a specific embodiment, the value of the preset torque can be 3 to 6 mN.m, that is, the preset torque can be any value between 3 and 6 mN.m (including the boundary value). Of course, the preset torque can also be other values, and the preset torque can be determined according to the torque corresponding to the pump body part 200. The working torque of the drainage pump is the torque during drainage work.

[0035] In the control method of the present invention, the motor speed of the drainage pump in the low torque working state less than or equal to the preset torque is adjusted to a preset range, and the maximum value of the preset range is equal to or less than 1.1 times the motor speed corresponding to the maximum working torque of the drainage pump. That is to say, the maximum value of the motor speed corresponding to the low torque working state is consistent with the existing normal characteristic curve of the motor ( Figure 1 The corresponding speed should be low, that is, the control method of the present invention can reduce the motor speed under low torque, thereby achieving the purpose of reducing noise. At the same time, a certain energy saving capability can be achieved by reducing the speed, that is, the speed reduction under low torque can reduce a part of the input power to achieve energy saving. In addition, reducing the speed can also reduce the temperature rise and improve product reliability.

[0036] This control method is not affected by voltage fluctuations, that is, the rotation speeds controlled by high voltage and low voltage are consistent. Through this control method, the rotation speed can be kept unchanged when the voltage fluctuates, that is, the flow rate remains unchanged and the rotation speed remains unchanged.

[0037] In the control method in the embodiment of the present invention, the motor speed corresponding to the maximum working torque of the drainage pump is defined as the first speed, the maximum value of the preset range is less than or equal to 1.05 times the first speed, and the minimum value of the preset range is equal to or greater than 0.95 times the first speed. That is to say, the value of the preset range can fluctuate within a range of 5% around the first speed.

[0038] The first rotational speed can be determined by the flow rate at a high head verified by experiments.

[0039] In the above range, the rotation speed of the drainage pump is basically maintained near the first rotation speed, and the noise is relatively small. Of course, the preset range is not limited to the above range.

[0040] Ideally, the preset range is a constant speed range, that is, when the working torque of the drainage pump is less than or equal to the preset torque, the motor speed is controlled to be at a constant speed, which can be equal to the speed of the drainage pump at the maximum working torque, that is, the first speed. By controlling the constant speed, the impeller can achieve a small change in the gas-liquid interface under different heads and water levels, thereby achieving the purpose of reducing noise.

[0041] In a specific implementation, the drainage pump includes a frequency converter for adjusting the working power frequency of the motor; the adjustment step S2 specifically includes:

[0042] When the working torque of the drainage pump is less than or equal to the preset torque, the working parameters of the frequency converter are adjusted to control the motor speed of the drainage pump to be within the preset range. This adjustment method is relatively simple and has high adjustment flexibility.

[0043] For an embodiment in which the drainage pump includes an MCU and a memory, the MCU has a driving circuit for driving the motor to rotate, and the memory pre-stores a first rotation speed, a maximum operating torque and a preset range corresponding to the type of the drainage pump motor.

[0044] The above adjustment steps specifically include:

[0045] When the working torque of the drainage pump under the current working condition is less than or equal to the preset torque, the MCU adjusts the voltage output to the drive circuit to control the motor speed to be within a preset range.

[0046] In this embodiment, the MCU is relatively small in size, which is conducive to the miniaturization design of the drainage pump, and the control reliability is also relatively high.

[0047] In another specific implementation, the motor is a brushless DC motor, and the adjustment step S2 specifically includes:

[0048] When the working torque of the drainage pump is less than or equal to the preset torque, the pulse width is adjusted to make the motor speed within the preset range.

[0049] In the embodiment of the present invention, the adjustment step S2 specifically includes:

[0050] S11, calculating the motor speed according to the number of pulses in a predetermined time period;

[0051] The predetermined time period can be determined according to the specific drainage pump. In a specific embodiment, the predetermined time period can be 0.5 seconds. Of course, in other drainage pumps, the predetermined time period can also be other values, such as 0.4S or 0.6S or 0.8S or 1S, etc.

[0052] S12, determining whether the motor speed is within a preset range, if the motor speed is within the preset range, executing S11, if not, executing S13;

[0053] S13, after performing pulse width modulation (PWM) according to a PID (proportional, integral, derivative) algorithm, execute S11.

[0054] The PID regulation response speed is relatively fast and the oscillation is relatively small. In addition, this control method realizes speed control through closed-loop control and pulse width modulation, and can achieve constant speed under different applied voltages and different load torques.

[0055] In the above embodiments, when the current working torque of the drainage pump is greater than the preset torque, the motor speed is less than or equal to the maximum value of the preset range. That is to say, the motor working curve formed by the control method of the present invention generally includes two parts: the first section and the second section, see Figure 4 , Figure 4 The working curves of the motor under two voltages are shown in , where curve m is the working curve of the motor under 12V voltage, and curve m' is the working curve of the motor under 11.5V voltage, the horizontal axis represents the torque, and the vertical axis represents the speed. Taking curve m as an example, curve m includes a first section m1 and a second section m2, wherein the horizontal axis range of the first section is: 0 to the preset torque section, the vertical axis of the first section is the speed, and the torque values ​​corresponding to each horizontal axis are all within the preset range, and the curve formed by the first section is basically a horizontal line or a curve fluctuating within the preset range. The horizontal axis of the second section is: greater than the preset torque section, and the curve of the second section is roughly a line segment with a predetermined slope.

[0056] The control method described above in the present invention may be integrated on a chip, and the chip may be a single chip or a dual chip.

[0057] The control method and the drainage pump provided by the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling a drainage pump, characterized in that: The drainage pump includes a motor, and the control method includes: Acquisition step: acquiring the working torque of the drainage pump in the current working condition according to the current load parameters, wherein the load parameters include one or more of the water level, the head, and the liquid viscosity; Adjustment step: judging the magnitude of the working torque under the current working condition and the pre-stored preset torque, and when the working torque under the current working condition is less than or equal to the preset torque, controlling the motor speed of the drainage pump to always be maintained within a preset range; The preset torque is equal to or less than the maximum working torque of the drainage pump, the motor speed corresponding to the maximum working torque of the drainage pump is defined as a first speed, and the maximum value of the preset range is equal to or less than 1.1 times of the first speed.

2. The control method of the drainage pump according to claim 1, characterized in that: The maximum value of the preset range is less than or equal to 1.05 times the first speed; the preset range includes a minimum value, and the minimum value is equal to or greater than 95% of the first speed; Alternatively, the preset range is a constant speed, and the constant speed is the first speed.

3. The control method of the drainage pump according to claim 2, characterized in that: The drainage pump includes a frequency converter for adjusting the working power frequency of the motor; the adjustment step specifically includes: When the working torque under the current working condition is less than or equal to the preset torque, the working parameters of the inverter are adjusted to control the motor speed of the drainage pump to be within a preset range.

4. The control method of the drainage pump according to claim 2, characterized in that: The drainage pump comprises an MCU and a memory, wherein the MCU has a driving circuit for driving the motor to rotate, and the memory pre-stores the first speed, the maximum working torque and the preset range corresponding to the motor type; The adjustment step specifically includes: When the working torque under the current working condition is less than or equal to the preset torque, the MCU adjusts the voltage output to the drive circuit to control the motor speed to be within the preset range.

5. The control method of the drainage pump according to claim 1, characterized in that: The motor is a brushless DC motor, and the adjustment step specifically includes: When the working torque of the current working condition is less than or equal to the preset torque, the pulse width is adjusted to make the motor speed within a preset range.

6. The control method of the drainage pump according to claim 5, characterized in that: The adjustment step specifically includes: S11, calculating the motor speed according to the number of pulses in a predetermined time period; S12, determining whether the motor speed is within a preset range, if the motor speed is within the preset range, executing S11, if not, executing S13; S13, after pulse width modulation according to PID algorithm, execute S11.

7. The control method of a drainage pump according to any one of claims 1 to 6, characterized in that: When the current working torque of the drainage pump is greater than the preset torque, the motor speed is less than or equal to the maximum value of the preset range.

8. The control method of a drainage pump according to any one of claims 1 to 6, characterized in that: The preset torque ranges from 3 to 6 mN.m.

9. A drainage pump, characterized in that: The invention comprises a motor part, a pump body part and a chip, wherein the motor part comprises a motor, and the control method of the drainage pump according to any one of claims 1 to 8 is integrated on the chip.

10. The drainage pump according to claim 9, characterized in that The chip is a single chip or a double chip.

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