Dialysis pump

Abstract

The utility model provides a dialysis pump, which belongs to the technical field of motors and comprises a rear end cover, a front end cover and screws, and the rear end cover is fixedly connected with the front end cover through the screws. The driving assembly is arranged in the rear end cover, the driving assembly comprises a central shaft, a winding insulator, a stator iron core, a rotor iron core, magnetic steel, a heat dissipation copper sheet and deep groove ball bearings, the central shaft is rotationally embedded in the inner wall of the rear end cover, and the deep groove ball bearings are arranged on the two sides of the central shaft in a sleeving mode. As the stepping motor always consumes the maximum current even in a static state, the efficiency is reduced and overheating is possibly caused, and meanwhile, the torque of the stepping motor is small, and loud noise is generated at a high speed, the porous sparse heat dissipation copper sheet is added between the rotor iron core and the magnetic steel, so that heat dissipation is ensured, and meanwhile, the heat dissipation efficiency is improved. Noise generated during operation can be reduced to a certain extent, and durability and the heat dissipation effect are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of motors, and particularly relates to a dialysis pump. Background Art

[0002] A dialysis pump is a device used in hemodialysis treatment. Its main function is to pump the patient's blood out of the body through a pumping method. After being filtered and purified by a dialyzer, the relatively clean blood is then re-infused back into the patient's body. The dialysis pump is usually used in conjunction with a dialyzer, blood tubing, etc. to jointly complete the hemodialysis treatment. The working principle of the dialysis pump is mainly to use mechanical force to drive the blood flow, so as to achieve the functions of blood extraction and re-infusion. During dialysis, the dialysis pump needs to strictly control the blood flow rate and pressure to ensure the safety and effectiveness of the treatment.

[0003] Working principle of the blood pump: The basic working principle of the blood pump is similar to the movement that occurs in the muscles of the gastrointestinal tract, causing a wave that induces a siphon effect. In a hemodialysis machine, a peristaltic pump is used to pump various liquids. The fluid is contained in a flexible tube installed inside a circular pump housing (although linear peristaltic pumps have been manufactured). A rotor with multiple rollers connected to the outer circumference of the rotor compresses the flexible tube. Usually, two or more rollers block the tube, intercepting the fluid between them. Then, the fluid is conveyed to the pump outlet under ambient pressure. When the rotor rotates, the compressed part of the tube is squeezed shut, forcing the pumped fluid to move through the tube.

[0004] Motor control, a stepper motor is a DC motor that works by converting electronic pulses into discrete mechanical motion. In other words, the motor moves based on a given pulse sequence. Therefore, generally, a stepper motor controller capable of generating periodic pulses is required. This product uses a DC brushed motor with a Hall encoder. The advantage is that the encoded motor can output the rotational speed of the motor as an encoded value. Thus, we can monitor the rotational speed of the motor at any time, achieve closed-loop control, and make the motor speed more stable.

[0005] The disadvantages of using a stepper motor as the power of the dialysis pump are mainly reflected in the following aspects:

[0006] Noise and vibration: The rotor of the stepper motor has a large mass and high inertia, and is prone to vibration and noise during high-speed operation. This may not only affect the running stability of the dialysis pump, but also have an adverse impact on the patient's treatment environment.

[0007] Heat generation problem: The working principle of the stepper motor is to control the position and speed through short-time instantaneous pulses. Prolonged operation is likely to cause the motor to heat up and may even burn out. During dialysis treatment, the dialysis pump needs to operate continuously for a long time, which may cause the stepper motor to generate too much heat, thereby affecting its performance and lifespan.

[0008] Control precision issue: During operation, a stepper motor needs to control the number and frequency of current pulses in real time to ensure precise control of position and speed. However, under large load variations, the control of current pulses can be interfered with, leading to unstable motion and even stepping out of control. In dialysis treatment, the load of the dialysis pump may change due to variations in the patient's blood flow, which can affect the control precision of the dialysis pump.

[0009] Efficiency issue: A stepper motor is controlled between continuous stops and starts, resulting in relatively low efficiency compared to other types of motors. In dialysis treatment, the dialysis pump needs to operate continuously for a long time. If the efficiency is too low, it may lead to increased energy consumption and thus increased treatment costs.

[0010] Lower precision: Compared with servo motors, stepper motors have lower precision. In dialysis treatment, precisely controlling the blood flow and the flow rate of dialysis fluid is crucial for the treatment effect. Therefore, a stepper motor may not be the best choice. Summary of the Utility Model

[0011] The purpose of the present utility model is to provide a dialysis pump, aiming to solve the problems raised in the background art.

[0012] A dialysis pump includes

[0013] A rear end cover, a front end cover, and screws. The rear end cover and the front end cover are fixedly connected by screws.

[0014] A drive assembly disposed inside the rear end cover. Among them: The drive assembly includes a central shaft, winding insulation, a stator core, a rotor core, a magnetic steel, a heat dissipation copper sheet, and a deep groove ball bearing. The central shaft is rotatably inserted into the inner wall of the rear end cover. The deep groove ball bearing is sleeved on both sides of the central shaft. The winding insulation is inserted into the inner wall of the stator core. The rotor core is sleeved on the outer wall of the central shaft. The heat dissipation copper sheet is sleeved on the outer wall of the central shaft. The magnetic steel is sleeved on the outer wall of the central shaft.

[0015] Further, one end of the central shaft protrudes, and the outer wall of the protruding end of the central shaft fits against the outer wall of the deep groove ball bearing.

[0016] Further, a circuit board is fixedly provided on one side of the outer wall of the rear end cover.

[0017] Further, one end of the screw is sleeved at the opening of the front end cover.

[0018] Further, one end of the central shaft penetrates through the central opening of the inner wall of the front end cover.

[0019] Further, the circuit board can implement the function of a Hall encoder.

[0020] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0021] Since the stepper motor always consumes the maximum current even when it is stationary, it will reduce efficiency and may cause overheating. At the same time, the stepper motor has a small torque and will generate a lot of noise at high speeds. Therefore, a porous and sparse heat-dissipating copper sheet is added between the rotor core and the permanent magnet. While ensuring heat dissipation, it can also reduce the noise generated during operation to a certain extent, improving durability and heat dissipation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings are used to provide a further understanding of the present utility model and constitute a part of the specification. Together with the embodiments of the present utility model, they are used to explain the present utility model and do not constitute a limitation to the present utility model. In the drawings:

[0023] Figure 1 is the front view of the present utility model;

[0024] Figure 2 is the sectional view of the present utility model;

[0025] Figure 3 is the partial half-sectional view of the present utility model;

[0026] Figure 4 is the three-dimensional view of the present utility model;

[0027] Figure 5 is the exploded three-dimensional view of the present utility model.

[0028] In the figures: 1, rear end cover; 2, front end cover; 3, central shaft; 4, screw; 5, winding insulation; 6, stator core; 7, rotor core; 8, permanent magnet; 9, heat-dissipating copper sheet; 10, deep groove ball bearing; 11, circuit board. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts shall fall within the protection scope of the present utility model.

[0030] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "top / bottom end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "provided with", "sheathed / connected", "connection", etc. shall be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0032] Please refer to Figures 1-5 , the technical solution provided by this embodiment is as follows:

[0033] A dialysis pump, comprising,

[0034] A rear end cover 1, a front end cover 2 and a screw 4, the rear end cover 1 and the front end cover 2 are fixedly connected by the screw 4;

[0035] A driving assembly, disposed inside the rear end cover 1, wherein: the driving assembly includes a central shaft 3, a winding insulation 5, a stator core 6, a rotor core 7, a permanent magnet 8, a heat dissipation copper sheet 9 and a deep groove ball bearing 10. The central shaft 3 is rotatably embedded in the inner wall of the rear end cover 1, the deep groove ball bearing 10 is sleeved on both sides of the central shaft 3, the winding insulation 5 is inserted into the inner wall of the stator core 6, the rotor core 7 is sleeved on the outer wall of the central shaft 3, the heat dissipation copper sheet 9 is sleeved on the outer wall of the central shaft 3, and the permanent magnet 8 is sleeved on the outer wall of the central shaft 3.

[0036] In a specific embodiment of the present utility model, the basic working principle of the blood pump or peristaltic pump is similar to the movement occurring in the gastrointestinal muscles, causing a kind of wave that induces a siphon effect. In a hemodialysis machine, the peristaltic pump is used to pump various liquids. The fluid is contained in a flexible tube installed inside a circular pump housing (although linear peristaltic pumps have been manufactured). A rotor with multiple rollers connected to the outer circumference of the rotor compresses the flexible tube. Usually, two or more rollers block the tube, intercepting the fluid between them. Then, the fluid is conveyed to the pump outlet under ambient pressure. When the rotor rotates, the compressed part of the tube is squeezed shut, forcing the pumped fluid to move through the tube. In this study, the motor driving the pump core is a stepper motor with a Hall encoder. The Hall encoder consists of a Hall code disk (magnetic ring) and Hall elements. The Hall code disk has different magnetic poles equally distributed on a circular plate with a certain diameter. The Hall code disk is coaxial with the motor. When the motor rotates, the Hall elements detect and output several pulse signals. To determine the rotation direction, generally two sets of square wave signals with a certain phase difference are output. For a traditional DC motor to control the speed, PWM speed regulation is required. By controlling the duty cycle, the speed of the motor can be adjusted. However, this control is unidirectional, that is, an open-loop control. It can only change the current speed of the motor, but the speed of the motor is unknown. That is, if some faults occur in the motor resulting in a decrease or increase in speed, it is impossible to detect it in a timely manner. The coded motor solves this problem well. The Hall encoder on the board of the coded motor consists of a code disk and Hall elements. The Hall code disk is coaxial with the motor spindle. Multiple magnetic poles are equally distributed on the code disk. When the motor rotates, the Hall elements will output several pulse signals. It is precisely by using these pulse signals to achieve the speed measurement of the motor and the determination of the motor rotation direction. Therefore, as the driving motor of the pump core, whenever the speed of the pump core changes, the current speed of the motor can be immediately monitored whether it is too high or too low, and then the motor speed can be adjusted to achieve closed-loop control. This is also beneficial to the safety of the patient. Suppose the motor of the pump core is a traditional DC motor. Then, when the motor speed changes due to some external factors, the blood in the hose driven by the pump core will also change. Given that the venous blood flow rate is a relatively constant speed, the change in the pump core speed is an extremely serious problem, which has threatened the life safety of the patient and is a problem that cannot be ignored. Therefore, using a coded motor that can monitor the speed in real time is the only choice. Closed-loop control can well ensure the stable speed of the pump core. In the actual application process, one end of the central axis 3 of the dialysis plate is installed inside the peristaltic pump. The Hall encoder on the circuit board is a sensor that converts the mechanical geometric displacement on the output shaft into pulse or digital quantity through magnetoelectric conversion. The Hall encoder consists of a Hall code disk (magnetic ring) and Hall elements. The Hall code disk has different magnetic poles equally distributed on a circular plate with a certain diameter. The Hall code disk is coaxial with the motor. When the motor rotates, the Hall elements detect and output several pulse signals. To determine the rotation direction,Generally, two square wave signals with a certain phase difference are output. The encoded motor outputs the encoded signal through two externally led encoding lines. After the core board receives this data, it can know the current speed of the motor through decoding. The basic principle is that the encoder can convert the number of rotations of the motor into a counting signal, and then calculate the speed of the motor based on the number of rotations measured per unit time. What the encoder measures is the original speed of the motor. To the actual output, there is still a reduction ratio. Due to the placement of the positions of the two Hall sensors A and B, there is a phase difference in the measured signals. The process of generating pulse signals for one rotation. The positions of the two sensors A and B are 45° different. This is only a schematic diagram of the principle of generating pulse signals. The actual number of pulses per rotation is determined by the actual number of N and S poles of the encoder. A larger number can improve the measurement accuracy. Assume that when the Hall sensor corresponds to the S pole, it corresponds to a high potential (HIGH), and when it corresponds to the N pole, it is a low potential (LOW). The pulse signal of the encoder will be sent through the signal line. The STM32 single-chip microcomputer can be used to monitor this pin. Each pulse change will be recorded and the count will be accumulated. By measuring the total number of pulses within a set time interval (such as 100 ms), it is possible to know how many rotations the motor has made. The motor parameters used in this study are: the number of pulses generated per rotation of the encoder is 11, and the reduction ratio is 30. Then the number of pulses corresponding to one rotation at the motor output end is: number of pulses = 11 (number of pulses corresponding to one rotation of the encoder) * 30 (number of rotations of the encoder). Assume that the total number of pulses measured within the time interval (T = 100 ms) is: m. Then the number of rotations within time T is: number of rotations = m / number of pulses, and the angular velocity is: w = 2Π * number of rotations / T. b. The decoding process is to capture the pulse signal generated by the encoder through the timer (TIMx) of the microcontroller, and then read the encoded value once every 5 ms through the timer interrupt. This process needs to calculate the angular velocity of the motor obtained through discrete mathematics calculation = motor speed × 2Π = encoder value × timer interrupt reading frequency ÷ motor reduction ratio ÷ encoding degree ÷ multiplication factor. The control of the speed is PWM+ = Kp * e(t) + Ki * ∫e(t)dt, where: PWM is the control quantity generated by the control system.,

[0037] Kp is the proportionality coefficient, which is used to adjust the immediate response speed of the control system to the error.

[0038] e(t) is the control error, that is, the deviation between the given value and the actual output value.

[0039] Ki is the integral gain (or called the integral coefficient), which is used to adjust the response of the control system to the error accumulation.

[0040] ∫e(t)dt is the integral of the error e(t) over time t, representing the cumulative value of the error.

[0041] The proportional link instantaneously reflects the deviation signal of the control system proportionally. Once the deviation occurs, the controller immediately generates a control action to reduce the deviation. Generally, as the value increases, the overshoot of the closed-loop system increases, and the system response speed accelerates. However, when it increases to a certain extent, the system will become unstable.

[0042] The integral link is mainly used to eliminate the static error and improve the non-error degree of the system. The strength of the integral action depends on the integral constant. The larger the integral constant, the weaker the integral action, and vice versa. Generally, under the condition of unchanged integral constant, the larger the integral constant, that is, the weaker the integral action, the smaller the overshoot of the closed-loop system, and the slower the system response speed.

[0043] Specifically, the outer wall of the protruding end of the central shaft 3 is attached to the outer wall of the deep groove ball bearing 10.

[0044] In a specific embodiment of the present utility model, the outer wall of the protruding end of the central shaft 3 is attached to the outer wall of the deep groove ball bearing 10, which can ensure stable support.

[0045] Specifically, a circuit board 11 is fixedly arranged on one side of the outer wall of the rear end cover 1.

[0046] In a specific embodiment of the present utility model, the circuit board 11 can achieve high-precision control.

[0047] Specifically, one end of the screw 4 is sleeved at the opening of the front end cover 2.

[0048] In a specific embodiment of the present utility model, one end of the screw 4 is sleeved at the opening of the front end cover 2, which can facilitate installation and disassembly.

[0049] Specifically, one end of the central shaft 3 penetrates through the central opening of the inner wall of the front end cover 2.

[0050] In a specific embodiment of the present utility model, one end of the central shaft 3 penetrates through the central opening of the inner wall of the front end cover 2, which can facilitate driving external equipment.

[0051] Specifically, the circuit board 11 can achieve the function of a Hall encoder.

[0052] In a specific embodiment of the present utility model, the circuit board 11 can achieve the function of a Hall encoder and can achieve high-precision control.

[0053] Working principle:

[0054] The motor that drives the pump core is a stepper motor with a Hall encoder. The Hall encoder consists of a Hall disk (magnetic ring) and Hall elements. The Hall disk has different magnetic poles evenly distributed on a circular plate of a certain diameter. The Hall disk is coaxial with the motor. When the motor rotates, the Hall elements detect and output several pulse signals. To determine the rotation direction, generally two square wave signals with a certain phase difference are output. For traditional DC motor speed control, PWM speed regulation is required. By controlling the duty cycle, the speed of the motor can be adjusted. However, this control is unidirectional, that is, open-loop control. It can only change the current speed of the motor, but the speed of the motor is unknown. That is, if some faults occur in the motor resulting in a decrease or increase in speed, it cannot be detected in time. The encoder motor solves this problem well. The Hall encoder on the encoder motor board is composed of a code disk and Hall elements. The Hall disk is coaxial with the motor spindle. There are multiple magnetic poles evenly distributed on the code disk. When the motor rotates, the Hall elements will output several pulse signals. It is precisely by using these pulse signals to achieve the speed measurement of the motor and the determination of the motor rotation direction. Therefore, as the drive motor of the pump core, whenever the speed of the pump core changes, it can immediately detect whether the current speed of the motor is too high or too low, and then adjust the motor speed to achieve closed-loop control. This is also beneficial to the safety of patients. Suppose the motor of the pump core is a traditional DC motor. Then when the motor speed changes due to some external factors, the blood in the hose driven by the pump core will also change. Knowing that the venous blood flow rate is a relatively constant speed, the change in the pump core speed is an extremely serious problem, which has threatened the life safety of patients and is a problem that cannot be ignored. Therefore, using an encoder motor that can monitor the speed in real time is the only choice. Closed-loop control can well ensure the stable speed of the pump core. In the actual application process, one end of the central axis 3 of the dialysis plate is installed inside the peristaltic pump. The Hall encoder on the circuit board is a sensor that converts the mechanical geometric displacement on the output shaft into pulse or digital quantity through magnetoelectric conversion. The Hall encoder consists of a Hall disk (magnetic ring) and Hall elements. The Hall disk has different magnetic poles evenly distributed on a circular plate of a certain diameter. The Hall disk is coaxial with the motor. When the motor rotates, the Hall elements detect and output several pulse signals. To determine the rotation direction, generally two square wave signals with a certain phase difference are output. The encoder motor outputs the encoding signal by leading out two encoding lines externally. After the core board receives these data, it can know the current speed of the motor through decoding. Basic principle: The encoder can convert the number of rotations of the motor into a counting signal, and then calculate the speed of the motor based on the number of rotations measured per unit time. What the encoder measures is the original speed of the motor. To the actual output, there is still a reduction ratio. Due to the position arrangement of the two Hall sensors A and B, there is a phase difference in the measured signals. The generation process of the pulse signals for one rotation. The positions of the two sensors A and B are 45° apart.Only as a schematic diagram of the principle of pulse signal generation, the actual number of pulses per revolution is determined by the actual number of N and S poles of the encoder. A larger number can improve the measurement accuracy. Assume that the Hall sensor corresponds to a high potential (HIGH) for the S pole and a low potential (LOW) for the N pole. The pulse signal of the encoder will be sent out through the signal line. The STM32 microcontroller can be used to monitor this pin. Each pulse change will be recorded and the count will be accumulated. By measuring the total number of pulses within a set time interval (e.g., 100 ms), we can know how many revolutions the motor has made. The motor parameters used in this study are: the number of pulses generated per revolution of the encoder is 11, and the reduction ratio is 30. Then the number of pulses corresponding to one revolution of the motor output is: number of pulses = 11 (number of pulses corresponding to one revolution of the encoder) * 30 (number of revolutions of the encoder). Assume that the total number of pulses measured within the time interval (T = 100 ms) is: m. Then the number of revolutions within time T is: number of revolutions = m / number of pulses, and the angular velocity is: w = 2Π * number of revolutions / T. b. The decoding process is to capture the pulse signal generated by the encoder through the timer (TIMx) of the microcontroller, and then read the encoded value once every 5 ms through the timer interrupt. This process requires calculating the angular velocity of the motor through discrete mathematics = motor speed × 2Π = encoder value × timer interrupt reading frequency ÷ motor reduction ratio ÷ coding degree ÷ multiplication factor. The control of the speed is PWM+ = Kp*e(t) + Ki*∫e(t)dt, where: PWM is the control quantity generated by the control system.,

[0055] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, 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 dialysis pump, characterized in that: include, A rear end cover (1), a front end cover (2) and screws (4), wherein the rear end cover (1) and the front end cover (2) are fixedly connected by the screws (4); A drive assembly is arranged inside the rear end cover (1), wherein: the drive assembly comprises a central shaft (3), a winding insulation (5), a stator core (6), a rotor core (7), a magnetic steel (8), a heat dissipation copper sheet (9) and a deep groove ball bearing (10); the central shaft (3) is rotatably embedded in the inner wall of the rear end cover (1); the deep groove ball bearing (10) is sleeved on both sides of the central shaft (3); the winding insulation (5) is inserted into the inner wall of the stator core (6); the rotor core (7) is sleeved on the outer wall of the central shaft (3); the heat dissipation copper sheet (9) is sleeved on the outer wall of the central shaft (3); and the magnetic steel (8) is sleeved on the outer wall of the central shaft (3).

2. A dialysis pump according to claim 1, characterized in that: One end of the central shaft (3) is arranged to protrude, and the outer wall of the protruding end of the central shaft (3) is fitted to the outer wall of the deep groove ball bearing (10).

3. A dialysis pump according to claim 2, characterized in that: A circuit board (11) is fixedly arranged on one side of the outer wall of the rear end cover (1).

4. A dialysis pump according to claim 3, characterized in that: One end of the screw (4) is sleeved on the opening of the front end cover (2).

5. A dialysis pump according to claim 4, characterized in that: One end of the central axis (3) passes through the central opening of the inner wall of the front end cover (2).

6. A dialysis pump according to claim 5, characterized in that: The circuit board (11) can realize the function of a Hall encoder.

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