High-precision water pump and flow measurement method

Abstract

The invention discloses a high-precision water pump which comprises a pump head and a driving motor, a rotating shaft of the driving motor is connected with and drives the pump head, the driving motor is a stepping motor, and the rotating speed and the rotating angle of the stepping motor are controlled through a flow controller. The stepping motor can operate at an extremely low rotating speed without reducing the torsion, when the pump head operates at the extremely low rotating speed, the pure water flow is correspondingly reduced, and meanwhile, when the stepping motor operates at a high speed, the torsion is not influenced, so that the large-range flow regulation supply requirement from the extremely low speed to the high speed of the water purifier is met; and flow measurement can be assisted, so that the measurement precision is improved.

Description

Technical Field

[0001] The present application belongs to the field of automatic control, and in particular relates to a high-precision water pump and a flow measurement method. Background Art

[0002] Laboratory water purifier is a kind of equipment specially used to produce high purity water in laboratory environment. It removes impurities and pollutants from tap water or other raw water sources through a series of complex physical, chemical and biological treatment steps to provide high purity water that meets experimental requirements.

[0003] The self-priming pump is a key component of the water supply in the pure water machine. It is responsible for providing power to the pure water and transporting the pure water in the water tank to the user's container through a pipe. Existing self-priming pumps are usually diaphragm self-priming water pumps driven by DC motors. The speed of the motor can be controlled by changing the DC voltage of the power supply or adjusting the duty cycle through PWM. Changing the speed of the DC motor can control the pure water flow. When the voltage or PWM of this method is reduced to a certain level, the torque of the motor is reduced and it cannot rotate directly, and the flow supply demand at extremely slow speeds cannot be met.

[0004] The rotor flowmeter is a key component for feedback of pure water flow rate and quantity in a pure water machine. It has higher accuracy at higher flow rates, but when the flow rate drops to a certain level, the water flow can no longer drive the internal rotor to rotate, and the water flow can no longer be accurately measured, which will cause large deviations when the user takes water in a certain quantity.

[0005] Therefore, a new type of high-precision water pump or metering technical solution is needed to solve the above problems. Summary of the invention

[0006] In order to address the deficiencies of the prior art, the present application provides a high-precision water pump and a flow measurement method, which can adjust the pure water flow in a pure water machine over a wide range from extremely low to extremely high flow rates, and can also perform precise quantitative control of pure water.

[0007] The technical effects to be achieved by this application are achieved through the following solutions:

[0008] According to the first aspect of the present application, a high-precision water pump is provided, comprising a pump head and a drive motor, wherein a rotating shaft of the drive motor is connected to and drives the pump head, the drive motor is a stepper motor, and the rotation speed and rotation angle of the stepper motor are controlled by a flow controller.

[0009] Preferably, the stepper motor is fixed to the pump head via an adapter sleeve, and the rotating shaft of the stepper motor is connected to the pump head via an adapter shaft.

[0010] Preferably, the water outlet of the pump head is connected to a flow meter, and the flow measured by the flow meter is fed back to the flow controller.

[0011] According to a second aspect of the present application, a flow measurement method using the above-mentioned high-precision water pump is provided, comprising the following steps:

[0012] Step 1: Count the flow rate of the flow meter at each flow rate and the pump flow rate fed back by the high-precision water pump at the corresponding speed;

[0013] Step 2: Compare the flow meter flow rate and the water pump flow rate at each flow rate with the actual flow rate, and obtain the deviation between the two flow measurement values ​​and the true value;

[0014] Step 3: Setting a complementary filtering algorithm according to the deviation between the flow measurement value and the true value;

[0015] Step 4: When measuring flow rate, the complementary filtering algorithm is used to calculate the real flow rate.

[0016] Preferably, the complementary filtering algorithm includes the following formula:

[0017] F=F1*y1+F2*y2

[0018] Among them: F is the real flow, F1 is the water pump flow, y1 is the proportion of the water pump flow, F2 is the flow meter flow, and y2 is the proportion of the flow meter flow.

[0019] Preferably, the values ​​of y1 and y2 at each flow rate are calculated based on the deviations of the flow meter flow rate and the water pump flow rate at each flow rate from the true values.

[0020] Preferably, step 4 also includes the following steps: in the case of a sudden flow change, calculating the magnitude of the sudden flow of the flow meter flow and the water pump flow, and adjusting the values ​​of y1 and y2 according to the magnitude of the sudden flow.

[0021] Preferably, the following formula is used to calculate the values ​​of y1 and y2 in the case of a mutation:

[0022] y1=y 1原 -(F 1现 -F 1前 )*x1

[0023] y2=y 2原 -(F 2现 -F 2前 )*x2

[0024] Among them, y 1原 is the proportion of the pump flow rate under non-mutation conditions, F 1现 and F 1前 are the pump flow rates before and after the mutation, respectively, and x1 is the adjustment parameter;

[0025] y2原 is the proportion of the pump flow rate under non-mutation conditions, F 2现 and F 2前 are the flowmeter flow rates before and after the mutation, respectively, and x2 is the adjustment parameter.

[0026] According to an embodiment of the present application, the beneficial effect of using the high-precision water pump is that the stepper motor can be operated at an extremely low speed without reducing the torque. When the pump head is operated at an extremely low speed, the pure water flow rate will also be reduced accordingly. At the same time, the torque will not be affected when the stepper motor is operated at a high speed, thereby achieving a wide range of flow regulation supply requirements of the pure water machine from extremely slow to high speed;

[0027] By adopting this flow measurement method, the flow can be accurately measured in various flow velocity ranges, which makes up for the shortcoming that the flow meter cannot drive its internal rotor to rotate and thus cannot measure at extremely low flow velocities due to water flow impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the existing technical solutions, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 This is a schematic diagram of the structure of a high-precision water pump in one embodiment of the present application;

[0030] Figure 2 for Figure 1 The control circuit structure diagram of medium and high precision water pumps;

[0031] Figure 3 This is a flow chart of a flow measurement method in one embodiment of the present application;

[0032] Figure 4 The figure is a comparison chart of the pump flow, flow meter flow and actual flow at different flow rates. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0034] like Figure 1 and Figure 2As shown, a high-precision water pump in an embodiment of the present application includes a pump head 150 and a drive motor, wherein the rotating shaft of the drive motor is connected to and drives the pump head 150, and the drive motor is a stepper motor 110, and the stepper motor 110 controls the rotation speed and rotation angle through a flow controller.

[0035] In this embodiment, the stepper motor 110 is fixed to the pump head 150 via an adapter sleeve 120 , the rotating shaft of the stepper motor 110 is connected to the pump head 150 via an adapter shaft 130 , and a bearing 140 is provided between the outer periphery of the adapter shaft 130 and the adapter sleeve 120 .

[0036] In this embodiment, a flow meter is connected to the water outlet of the pump head 150, and the flow rate measured by the flow meter is fed back to the flow controller. The measurement feedback of the flow meter can be used to control the rotation speed of the stepper motor 110.

[0037] A complementary filtering algorithm is provided in the flow controller, and according to the algorithm, the current real flow can be counted in real time, and the rotation speed of the stepper motor 110 is changed according to the real flow, so as to control the flow of the water pump.

[0038] The stepper motor 110 can run at an extremely low speed without reducing the torque. When the pump head 150 runs at an extremely low speed, the pure water flow rate will also be reduced accordingly. At the same time, the torque will not be affected when the stepper motor 110 runs at high speed, thereby achieving a wide range of flow regulation supply needs from extremely slow to high speed of the pure water machine.

[0039] like Figure 3 As shown, a flow measurement method using the above-mentioned high-precision water pump in an embodiment of the present application includes the following steps:

[0040] Step 1: Count the flow rate of the flow meter at each flow rate and the pump flow rate fed back by the high-precision water pump at the corresponding speed;

[0041] In this step, the flow meter flow is counted at each flow rate; since the rotation speed of the water pump is proportional to the flow rate, the rotation speed of the water pump at each flow rate can reflect the current flow rate, which is counted as the water pump flow rate.

[0042] Since the water pump is driven by a stepper motor, the speed of the stepper motor can be adjusted at a precise angle, so the precise speed of the stepper motor can be collected and the water pump flow rate can be fed back.

[0043] Step 2: Compare the flow meter flow rate and the water pump flow rate at each flow rate with the actual flow rate, and obtain the deviation between the two flow measurement values ​​and the true value;

[0044] In this step, by Figure 4It can be seen from the flow statistics chart that at lower flow rates (0-2L / min), the flow rate fed back by the high-precision water pump based on the current speed basically coincides with the actual flow curve, but as the flow rate increases (2-4L / min), its flow curve gradually deviates from the actual flow curve. At the same time, at lower flow rates (0-2L / min), the flow curve measured by the flow meter has a large deviation from the actual flow curve, but as the flow rate increases (2-4L / min), its curve gradually coincides with the actual flow curve.

[0045] The actual flow rate can be calculated based on the amount of water measured by a measuring cup per unit time at the current speed, which is the real flow rate.

[0046] Step 3: Setting a complementary filtering algorithm according to the deviation between the flow measurement value and the true value;

[0047] In this step, it can be known from the above three curves that, when the flow rate is constant, there must be a specific gravity y, so that the following formula is valid:

[0048] F1*y+F2*(y-1)=F

[0049] Among them, F1: pump flow, F2: flow meter flow, F: real flow;

[0050] By calculating the specific gravity y at each flow rate and F1 and F2 respectively, the relationship curves between the specific gravity and the two measurement methods at different flow rates can be obtained, which are y1 = f(F1) and y2 = f(F2) respectively;

[0051] Then the final complementary filtering algorithm formula is as follows:

[0052] F=F1*y1+F2*y2

[0053] Among them: F is the real flow, F1 is the water pump flow, y1 is the proportion of the water pump flow, F2 is the flow meter flow, and y2 is the proportion of the flow meter flow.

[0054] The values ​​of y1 and y2 counted at each flow rate are saved. In the subsequent flow measurement, the corresponding specific gravity values ​​are multiplied and added according to the size of the water pump flow or flow meter flow to obtain the corresponding real flow.

[0055] Step 4: When measuring flow rate, the complementary filtering algorithm is used to calculate the real flow rate.

[0056] In this step, during the flow measurement process, the flow rate fed back by the current high-precision water pump and the flow rate fed back by the flow meter are counted respectively. According to the water pump flow rate and the flow meter flow rate, the corresponding y1 and y2 are selected respectively, and then the complementary filtering algorithm is used to calculate the current real flow rate.

[0057] During the flow measurement process, sudden flow changes may occur due to bubbles and other reasons. In the case of sudden flow changes, the accuracy of the flow meter flow or the water pump flow may decrease. It is necessary to calculate the sudden flow rate of the flow meter flow and the water pump flow, and adjust the values ​​of y1 and y2 according to the sudden flow rate.

[0058] The method of identifying sudden changes in traffic is to set a sudden change threshold. When the size of the sudden change in traffic is greater than the threshold, the traffic is considered to have changed suddenly, and the corresponding formula is selected according to the size of the sudden change in traffic to recalculate the values ​​of y1 and y2.

[0059] The following formula is used to calculate the values ​​of y1 and y2 in the case of mutation:

[0060] y1=y 1原 -(F 1现 -F 1前 )*x1

[0061] y2=y 2原 -(F 2现 -F 2前 )*x2

[0062] Among them, y 1原 is the proportion of the pump flow rate in the non-mutated case, that is, y 1原 =f(F 1前 ), F 1现 and F 1前 are the pump flow rates before and after the mutation, respectively, and x1 is the adjustment parameter;

[0063] y 2原 is the proportion of the pump flow rate in the non-mutated case, that is, y 2原 =f(F 2前 ), F 2现 and F 2前 are the flowmeter flow rates before and after the mutation, respectively, and x2 is the adjustment parameter.

[0064] This method increases the calculation weight of the flow measurement method results that are closer to the true value at the same flow rate, and reduces the calculation weight of the flow measurement method results with large flow measurement mutations, by using a special complementary filtering algorithm written in the controller. The pure water flow obtained by flow meter feedback and the pure water flow calculated by motor speed are complementary filtered and fused to obtain a pure water flow that is closer to the true value, which can make the quantification of the pure water machine more accurate.

[0065] The complementary filtering algorithm can also accurately control the actual flow rate. After the required flow rate is input into the controller, the controller can calculate the current actual flow rate based on the current flow meter flow and the water pump flow rate, and compare it with the required flow rate to obtain the difference. The speed of the water pump can be accurately controlled according to the difference, thereby obtaining a more accurate flow rate.

[0066] According to an embodiment of the present application, the beneficial effect of using the high-precision water pump is that the flow measurement method can accurately measure the flow rate within each flow rate range, making up for the shortcoming that the flow meter cannot drive the internal rotor to rotate under extremely low flow rates, and thus cannot measure. Figure 4 It can be seen that at extremely low flow rates, the curves of the pump flow rate and the real flow rate coincide with each other, so a higher weight is given to the pump flow rate to reflect the real flow rate.

[0067] It should be noted that the above detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present application belongs.

[0068] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0069] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0070] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0071] For ease of description, spatially relative terms, such as "above", "above", "on the upper surface of", "above", etc., may be used herein to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways, such as rotated 90 degrees or in other orientations, and the spatially relative descriptions used herein are interpreted accordingly.

[0072] In the above detailed description, reference is made to the accompanying drawings, which form a part of this document. In the accompanying drawings, similar symbols typically identify similar components unless the context indicates otherwise. The illustrated embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein.

[0073] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-precision water pump, comprising a pump head and a drive motor, wherein the rotating shaft of the drive motor is connected to and drives the pump head, characterized in that: The driving motor is a stepping motor, and the rotation speed and rotation angle of the stepping motor are controlled by a flow controller.

2. The high-precision water pump according to claim 1, characterized in that: The stepper motor is fixed to the pump head via an adapter sleeve, and the rotating shaft of the stepper motor is connected to the pump head via an adapter shaft.

3. The high-precision water pump according to claim 1, characterized in that: The water outlet of the pump head is connected to a flow meter, and the flow measured by the flow meter is fed back to the flow controller.

4. A flow measurement method using a high-precision water pump according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: Count the flow rate of the flow meter at each flow rate and the pump flow rate fed back by the high-precision water pump at the corresponding speed; Step 2: Compare the flow meter flow rate and the water pump flow rate at each flow rate with the actual flow rate, and obtain the deviation between the two flow measurement values ​​and the true value; Step 3: Setting a complementary filtering algorithm according to the deviation between the flow measurement value and the true value; Step 4: When measuring flow rate, the complementary filtering algorithm is used to calculate the real flow rate.

5. The flow measurement method according to claim 4, characterized in that: The complementary filtering algorithm includes the following formula: F=F1*y1+F2*y2 Among them: F is the real flow, F1 is the water pump flow, y1 is the proportion of the water pump flow, F2 is the flow meter flow, and y2 is the proportion of the flow meter flow.

6. The flow measurement method according to claim 5, characterized in that: The values ​​of y1 and y2 at each flow rate are calculated based on the deviations of the flow meter flow rate and the water pump flow rate at each flow rate from the true values.

7. The flow measurement method according to claim 6, characterized in that: Step 4 also includes the following steps: in the case of a sudden flow change, calculating the sudden flow size of the flow meter flow and the water pump flow, and adjusting the values ​​of y1 and y2 according to the sudden flow size.

8. The flow measurement method according to claim 7, characterized in that: The following formula is used to calculate the values ​​of y1 and y2 in the case of mutation: in, is the proportion of the pump flow rate under non-mutation conditions, and are the pump flow rates before and after the mutation, respectively, and x1 is the adjustment parameter; is the proportion of the pump flow rate under non-mutation conditions, and are the flowmeter flow rates before and after the mutation, respectively, and x2 is the adjustment parameter.

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