WO2020164165A1 - 基于在线监测的抗沉降磁流变阻尼器 - Google Patents

基于在线监测的抗沉降磁流变阻尼器 Download PDF

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Publication number
WO2020164165A1
WO2020164165A1 PCT/CN2019/075709 CN2019075709W WO2020164165A1 WO 2020164165 A1 WO2020164165 A1 WO 2020164165A1 CN 2019075709 W CN2019075709 W CN 2019075709W WO 2020164165 A1 WO2020164165 A1 WO 2020164165A1
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ultrasonic
magnetorheological
transducer
sedimentation
ultrasonic transducer
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PCT/CN2019/075709
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English (en)
French (fr)
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张红辉
陶泽军
廖昌荣
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重庆大学
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Publication of WO2020164165A1 publication Critical patent/WO2020164165A1/zh

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
    • F16F9/32—Details
    • F16F9/53—Means for adjusting damping characteristics by varying fluid viscosity, e.g. electromagnetically

Definitions

  • the invention relates to the field of magnetorheological damper, in particular to an anti-sedimentation magnetorheological damper based on online monitoring.
  • Magnetorheological fluid is a controllable fluid, which can be made into various devices with controllable damping characteristics by adding a magnetic field to control the apparent viscosity, such as dampers, clutches, brakes, etc.
  • Magnetorheological fluid is a suspension composed of small soft magnetic particles with high permeability and low hysteresis and a non-magnetic fluid. This kind of suspension exhibits low-viscosity Newtonian fluid characteristics under zero magnetic field conditions; while under the action of a strong magnetic field, it exhibits high-viscosity, low-fluidity Bingham characteristics.
  • Ferromagnetic particles are used as the dispersed phase in the magnetorheological fluid with a particle size of 1-20 ⁇ m. They belong to a coarse dispersion system. The Brownian motion is weak and the gravitational field is strong. Due to the density mismatch between the dispersed phase and the dispersion medium, the magnetorheological fluid settles The problem cannot be avoided. Under the action of additives, the practical magnetorheological fluid has certain anti-settling stability, but it still cannot adapt to possible long-term standing conditions.
  • thixotropic agent In order to overcome the settlement problem of magnetorheological fluids, various additives and surface modification of the dispersed phase are used to try to improve this problem.
  • the most widely used additive is a thixotropic agent, the principle of which is that the thixotropic agent forms a weak three-dimensional structure to assist in supporting the magnetic particles.
  • the thixotropic agent has a higher viscosity at low shear rate, which is beneficial to the stability of the sedimentation. Under high shear rate, these weak spatial structures are easily destroyed and the viscosity decreases, which is conducive to maintaining a good magnetorheological effect.
  • the addition of the thixotropic agent improves the settlement problem of the magnetorheological fluid, and prolongs the standing time for visible settlement to 1 month or more, but it cannot be completely solved.
  • the surface of the magnetic particles is modified or coated to form a core-shell structure, which can reduce the overall density of the particles and increase the surface area of the particles, thereby improving the suspension stability of the particles in the carrier liquid; separated by the coating layer, reducing the particle size
  • the adsorption between the two can improve the redispersibility of the magnetorheological fluid. This method can improve the sedimentation problem of magnetorheological fluid to a certain extent.
  • the purpose of the present invention is to solve the problems existing in the prior art.
  • the anti-sedimentation magnetorheological damper based on online monitoring mainly includes a magnetorheological damper, an ultrasonic transducer and a processing circuit.
  • the magnetorheological damper includes a working cylinder and a motor for realizing magnetorheological fluid dispersion. Magnetorheological fluid is installed in the working cylinder.
  • the ultrasonic transducer is attached to the side wall at the bottom of the working cylinder.
  • the ultrasonic transducer is an ultrasonic transmitting transducer and an ultrasonic receiving transducer or an ultrasonic transducer integrating transceiver.
  • the ultrasonic transmitting transducer and the ultrasonic receiving transducer are symmetrical about the central axis of the working cylinder.
  • the distance between the ultrasonic transmitting transducer and the ultrasonic receiving transducer is denoted as L. L>0
  • the ultrasonic transducer integrated with the transceiver uses the cylinder surface facing the working cylinder as the reflecting surface, and the projection of the ultrasonic transducer on the reflecting surface is the reflecting point.
  • the transmitting and receiving integrated ultrasonic transducer and the reflection point continuously pass through the central axis of the working cylinder.
  • the wiring harness of the ultrasonic transducer is connected to the processing circuit.
  • the processing circuit receives the receiving voltage Ex of the ultrasonic transducer through the wire harness, and obtains the magnetorheological fluid dispersed phase volume concentration at of the ultrasonic propagation channel at time t , hereinafter referred to as the magnetorheological fluid dispersed phase volume concentration as the concentration.
  • a 0 is the initial state concentration.
  • a x is the concentration change caused by sedimentation.
  • the initial state concentration a 0 satisfies the following formula:
  • E0 is the receiving voltage of the ultrasonic transducer in the initial state of the magnetorheological fluid.
  • the received voltage E0 when the magnetorheological fluid is in the initial state is stored in the processing circuit.
  • E r is the emission voltage of the ultrasonic transducer in the initial state of the magnetorheological fluid.
  • the concentration change a x caused by sedimentation is as follows:
  • the ultrasonic transducer is a transceiver integrated ultrasonic transducer, then L is twice the diameter of the working cylinder. If the ultrasonic transducer is an ultrasonic transmitting transducer and an ultrasonic receiving transducer, then L is the distance between the ultrasonic transmitting transducer and the ultrasonic receiving transducer.
  • the processing circuit obtains the sedimentation concentration change a x according to formula (3), and determines whether the magnetorheological fluid needs to be dispersed. When it is determined that the concentration change a x is greater than a certain threshold k, the processing circuit outputs an electrical excitation signal to the outside; if not, no electrical excitation signal is generated. Based on the electrical excitation signal output by the processing circuit, the magnetorheological damper drives the motor to disperse the magnetorheological fluid.
  • the invention proposes an anti-settling magnetorheological damper based on online monitoring based on the propagation mechanism of ultrasonic waves in suspension, which can realize the magnetorheological fluid of the magnetorheological damper The autonomous regulation and anti-sedimentation.
  • Figure 1 is a schematic diagram of the structure of an anti-settling magnetorheological damper based on online monitoring
  • Figure 2 is a schematic diagram I of the structure of a magnetorheological damper
  • Figure 3 is a trigger circuit diagram
  • Figure 4 is the working principle diagram of LM1812
  • Figure 5 is a schematic diagram of the transformer's turns ratio setting
  • Figure 6 is a schematic diagram II of the structure of a magnetorheological damper
  • Figure 7 is a schematic diagram of the structure of the bottom cover of the magnetorheological damper
  • Figure 8 is a schematic diagram of the structure of the rotor
  • FIG. 9 is a schematic diagram of the structure of the stator
  • Figure 10 is a schematic structural view of the top cover
  • Figure 11 is a schematic view of the structure of the working cylinder
  • FIG. 12 is a flowchart of the processing circuit
  • liquid cylinder 12 bottom cover 13, circular ring I131, disk I132, circular hole I1321, counterbore 1322, positioning column 14, through hole II141, rotor 15, extension shaft 151, squirrel cage 152, spiral rib Rib 153, stator 16, outer cylinder 161, inner cylinder 162, slot II 1621, magnetic pole 163, winding 164, winding lead 165, top cover 17, step ring 171, disc II 172, circular hole II 1721, spoke 173, working cylinder 11.
  • the anti-settling magnetorheological damper based on online monitoring mainly includes magnetorheological damper 1, ultrasonic transducer 2 and processing circuit 3.
  • the magnetorheological damper 1 includes a working cylinder 11 and a motor for realizing magnetorheological fluid dispersion.
  • the working cylinder 11 is filled with magnetorheological fluid.
  • the magnetorheological damper 1 After receiving the electrical excitation signal from the processing circuit 3, the magnetorheological damper 1 drives the motor to disperse the magnetorheological fluid.
  • the ultrasonic transducer 2 is attached to the side wall at the bottom of the working cylinder 11.
  • the wire harness 21 of the ultrasonic transducer 2 extends out of the magnetorheological damper 1 and is connected to the processing circuit 3.
  • the magnetorheological fluid settles at the bottom of the cylinder to make the dispersed phase have the highest volume fraction.
  • the ultrasonic transducer is located at the bottom of the cylinder and is arranged close to the circumference of the cylinder so that the acoustic emission direction passes through the axis of the cylinder. When the ultrasonic transmitter emits After a specific frequency of ultrasound, it is received by the opposite ultrasound receiver.
  • the ultrasonic transducer 2 is an ultrasonic transmitting transducer and an ultrasonic receiving transducer or an ultrasonic transducer integrating transceiver.
  • the ultrasonic transmitting transducer and the ultrasonic receiving transducer are symmetrical about the central axis of the working cylinder.
  • the distance between the ultrasonic transmitting transducer and the ultrasonic receiving transducer is denoted as L. L>0
  • the ultrasonic transducer integrated with the transceiver uses the cylinder surface facing the working cylinder as the reflection surface, and the projection of the ultrasonic transducer on the reflection surface is the reflection point.
  • the transmitting and receiving integrated ultrasonic transducer and the reflection point continuously pass through the central axis of the working cylinder.
  • the ultrasonic transducer receives the reflected ultrasonic signal, it carries the attenuation information of the ultrasonic wave propagated in the magnetorheological fluid in the sinking state, and is transmitted to the processing circuit through the wire harness 21 for processing and output.
  • the magnetorheological damper When the magnetorheological damper is in a static state, the magnetorheological fluid settles, and the processing circuit 3 receives the receiving voltage Ex of the ultrasonic transducer 2 through the harness 21 to obtain the magnetorheological fluid dispersion of the ultrasonic propagation channel at time t volume concentration a t.
  • the magnetorheological fluid concentration at time t satisfies the following formula:
  • a 0 is the concentration when the magnetorheological fluid is in the initial state, that is, when the sedimentation has not occurred. If the ultrasonic transducer 2 is a transceiver integrated ultrasonic transducer, then L is twice the diameter of the cylinder barrel of the working cylinder 11. If the ultrasonic transducer 2 is an ultrasonic transmitting transducer and an ultrasonic receiving transducer, then L is the distance between the ultrasonic transmitting transducer and the ultrasonic receiving transducer. E0 is the receiving voltage of the ultrasonic transducer 2 in the initial state of the magnetorheological fluid.
  • the initial state concentration a 0 satisfies the following formula:
  • E0 is the receiving voltage of the ultrasonic transducer in the initial state of the magnetorheological fluid.
  • the received voltage E0 when the magnetorheological fluid is in the initial state is stored in the processing circuit.
  • E r is the emission voltage of the ultrasonic transducer in the initial state of the magnetorheological fluid.
  • a x is the concentration change caused by sedimentation, as shown below:
  • the processing circuit (3) outputs an external electrical excitation signal. After receiving the electrical excitation signal, the magnetorheological damper drives the motor to disperse the magnetorheological fluid.
  • the magnetorheological damper 1 After the magnetorheological damper 1 receives the driving signal, it rotates the rotor under the excitation of the stator rotating magnetic field, and with the help of the spiral of the rotor outer circle, the magnetorheological fluid can form a flow circuit inside the damper to overcome the magnetic field.
  • the processing circuit 3 can adopt the LM1812 professional integrated circuit, which not only has fewer peripheral components, simple circuit, but also has better stability and reliability.
  • Ultrasonic integrated circuit The LM1812 chip includes a pulse modulated type C oscillator, which requires a periodic trigger signal to trigger the timing of the circuit. This embodiment uses a 555 timer to form a multivibrator with a certain duty cycle.
  • the trigger circuit is shown in Figure 3. In this circuit, the charging circuit and the discharging circuit are independent of each other, and the square wave signal is obtained by charging and discharging the capacitor C11.
  • the charging circuit is composed of R3 and C11 and outputs a high level.
  • the discharge circuit is composed of R4 and C11, and outputs low level.
  • LM1812 The working principle of LM1812 is shown as in Fig. 4.
  • Pin 1 is connected with L1 and C1 to form a pulse-modulated type C oscillator, which determines the operating frequency of the transmitter and receiver.
  • the operating frequency can reach 325kHz.
  • the value of L1 and C1 can be determined according to the required ultrasonic frequency.
  • Pin 8 is the sending control terminal, which is connected to pin 3 of the multivibrator formed by the 555 timer. When pin 8 is high, the chip is in the sending mode. At this time, the L1 and C1 oscillation tank circuits are switched to the oscillation mode, and the oscillation After the signal is amplified by the driver, it is output through pins 13 and 6.
  • a transformer should be connected between pins 6 and 13 to match the impedance of the ultrasonic transmitter. Taking 40kHz and 200kHz as examples, the transformer turns can be set according to Figure 5. Number ratio. After the output transformer is built, the current of pin 6 should be tested to ensure that the maximum current value of pin 6 cannot exceed 1A. Otherwise, the chip may be damaged due to overload phenomenon due to excessive current. If you actually need more power, you can use an external pulse amplifier to achieve the need, and the output current can reach up to 5A.
  • LM1812 When pin 8 is low, LM1812 is in receiving mode.
  • the input current of pin 8 is designed in the range of 1-10mA.
  • the power supply voltage of the LM1812 is 12V, a 10k resistor is added to pin 8.
  • the AD637 root mean square detector circuit is used to calibrate the ultrasonic transmitting and receiving signals after obtaining the effective values, and the relationship between the output voltage and the concentration of magnetorheological fluid can be obtained.
  • the processing circuit 3 retrieves the voltage E0 and the length L, and obtains the value of the ultrasonic echo voltage, and calculates the concentration change a x of the magnetorheological fluid. If the concentration change value is greater than 15%-25%, the reaction is triggered
  • the active dispersion device that is, the motor, includes the positioning column 14 of the anti-settling magnetorheological damper, the rotor 15 and the stator 16. In this embodiment, the range of the threshold k is set to [0.15, 0.25].
  • the magnetorheological damper 1 mainly includes a working cylinder 11, a liquid cylinder 12, a bottom cover 13, a top cover 17, a piston assembly 18, a piston rod 19 and a motor.
  • the motor includes a positioning column 14, a rotor 15 and a stator 16.
  • the liquid cylinder 12 is a hollow cylinder, and the opening at the lower end has threads.
  • the liquid cylinder 12 and the bottom cover 13 are sealed by an O-ring.
  • the upper end of the bottom cover 13 is a ring I131.
  • the outer wall of the ring I131 has threads.
  • the lower end of the bottom cover 13 is a disc I132.
  • the center of the end surface of the disk I132 has a circular hole I1321.
  • the end surface of the disc I132 is provided with several counterbores 1322 on the same circumference.
  • the upper end of the bottom cover 13 is installed at the opening of the lower end of the liquid cylinder 12.
  • the positioning column 14 is installed on the step of the counterbore 1322.
  • the positioning pillar 14 has a through hole II141 inside.
  • the through hole II141 is connected to the counterbore 1322 of the bottom cover 13.
  • the rotor 15 is a cylinder, and the center of the two ends of the rotor 15 has an extension shaft 151.
  • a squirrel cage 152 is embedded in the rotor 15.
  • the outer circumferential wall of the rotor 15 is provided with spiral ribs 153.
  • the rotor 15 is located in the liquid cylinder 12, and the protruding shaft 151 at the lower end thereof is supported in the circular hole I1321 of the bottom cover 13.
  • the rotor 15 is made of soft magnetic material.
  • the stator 16 is made of laminated silicon steel sheets.
  • the stator 16 includes an outer cylinder 161 and an inner cylinder 162.
  • the inner cylinder 162 is located inside the outer cylinder 161.
  • a number of magnetic poles 163 are arranged between the inner cylinder 162 and the outer cylinder 161.
  • a winding 164 is wound on each magnetic pole 163.
  • the inner wall of the inner cylinder 162 is evenly distributed with a plurality of through grooves II1621 passing through the two ends of the inner cylinder 162.
  • Each of the inner walls of the inner cylinder 162 corresponding to the adjacent magnetic poles 163 has a through slot II1621.
  • the stator 16 is sheathed on the rotor 15 and located in the liquid cylinder 12, and its lower end is fixed on the positioning column 14.
  • An inner passage is formed between the stator 16 and the rotor 15.
  • An outer channel is formed between the stator 16 and the liquid cylinder 12. The stator 16 is supported by the positioning column 14 to form a space connecting the inner channel and the outer channel.
  • the winding lead 165 of the stator 16 is led out through the through hole II141 on the positioning column 14 and passes through the bottom cover 13 through the counterbore 1322.
  • the top cover 17 includes a step ring 171 and a disc II172.
  • the disc II172 is located in the step ring 171, and the center of its end surface has a circular hole II1721.
  • the disc II172 is connected to the step ring 171 through spokes 173 in succession.
  • the top cover 17 is installed on the upper end of the stator 16.
  • the protruding shaft 151 at the upper end of the rotor 15 is supported in the round hole II1721 of the top cover 17.
  • the working cylinder 11 is cylindrical.
  • a plurality of through grooves I111 and a plurality of through holes I112 are evenly distributed in the circumferential direction of the working cylinder 11, wherein the through grooves I111 are located on the inner circular surface of the working cylinder 11, and the position of the through grooves I111 is recorded as the equilibrium position.
  • the working cylinder 11 is located in the liquid cylinder 12 and its lower end is sleeved on the steps of the step ring 171.
  • the working cylinder 11 contains magnetorheological fluid.
  • the piston assembly 18 is located in the working cylinder 11 and has a gap with the working cylinder 11.
  • the piston rod 19 is mounted on the piston assembly 18 to push the piston assembly 18 to reciprocate in the working cylinder 11.
  • the winding 164 receives the electrical excitation signal from the processing circuit 3, a rotating magnetic field is formed in the stator 16, the squirrel cage 152 of the rotor 15 cuts magnetic lines of force to generate an induced current and is subjected to magnetic force to drive the rotor 15 to rotate.
  • the spiral ribs 153 drive the magnetorheological fluid to flow in the inner channel and flow axially, and flow to the outer channel.
  • the magnetorheological fluid flowing out of the channel passes through the gap between the working cylinder 11 and the liquid cylinder 12, and flows into the working chamber through the through groove 1701 and the through hole I112.
  • the magnetorheological fluid flowing out of the channel passes through the gap between the working cylinder 11 and the liquid cylinder 12 and passes through the through hole I112. It flows into the working cylinder 11 to form a flow circuit, thereby realizing an effective magnetorheological fluid redispersion.
  • the excitation mode of the winding 164 in the stator 16 can be changed at this time to generate a uniform magnetic field distribution, which will fill the inner channel with a uniform and uniform magnetic field, thereby effectively regulating the piston assembly 8 Magnetorheological damping force during operation.
  • the protruding shafts 151 at both ends of the rotor 15 are supported by rolling bearings or sleeves, and the sleeves are made of polytetrafluoroethylene, so as to reduce friction between the protruding shafts 151 and the top cover 17 and bottom cover 13 at both ends.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
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  • Mechanical Engineering (AREA)
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Abstract

一种基于在线监测的抗沉降磁流变阻尼器，主要包括抗沉降磁流变阻尼器（1）、超声波换能器（2）和处理电路（3）。该磁流变阻尼器（1）具有工作缸（11），当磁流变阻尼器（1）处于静置状态时，磁流变液发生沉降，处理电路（3）通过线束不断获取超声波换能器（2）的接收电压Ex，并计算得到t时刻因沉降导致的浓度变化a x，当达到设定阈值k时，向所述磁流变阻尼器发送电激励信号，驱动电机在磁流变阻尼器内组织流动循环，进行磁流变液分散。该技术方案针对竖向使用的磁流变阻尼器，基于超声波在悬浮液中的传播机理，提出一种基于在线监测的抗沉降磁流变阻尼器，可以实现磁流变阻尼器的磁流变液的自主调控和抗沉降。

Description

基于在线监测的抗沉降磁流变阻尼器 技术领域
本发明涉及磁流变阻尼器领域，具体是基于在线监测的抗沉降磁流变阻尼器。
背景技术
磁流变液(Magnetorheological Fluid,简称MR流体)属可控流体，可以通过外加磁场控制器表观粘度，从而制作成各种具有可控阻尼特性的器件，如阻尼器、离合器、制动器等。磁流变液是由高磁导率、低磁滞性的微小软磁性颗粒和非导磁性液体混合而成的悬浮体。这种悬浮体在零磁场条件下呈现出低粘度的牛顿流体特性；而在强磁场作用下，则呈现出高粘度、低流动性的Bingham体特性。
铁磁性颗粒作为磁流变液中的分散相，粒径为1-20μm，属于粗分散体系，布朗运动弱而重力场强，由于分散相与分散介质的密度失配，磁流变液的沉降问题无法避免，在添加剂的作用下，实用化的磁流变液具有一定的抗沉降稳定性，但仍然无法适应可能的长期静置条件。
为了克服磁流变液的沉降问题，人们使用各种添加剂和分散相表面改性等方法试图改善这一问题。最广泛使用的添加剂为触变剂，其原理在于，触变剂形成微弱的三维结构来辅助支撑磁性颗粒。触变剂在低剪切率下的黏度较大，此时有利于沉降稳定性。而在高剪切率下，这些微弱的空间结构轻易被破坏，黏度下降，有利于维持较好的磁流变效应。触变剂的加入改善了磁流变液的沉降问题，使发生肉眼可见的沉降静置时间延长至1个月或以上，但无法完全解决。对磁性颗粒表面进行修饰或包覆，形成核壳结构，可以减小颗粒整体密度，增大颗粒表面积，从而提高颗粒在载体液中的悬浮稳定性；受包覆层隔离，减小了颗粒之间的吸附作用，可以提高磁流变液的可再分散能力。这种方法可以一定程度上改善磁流变液的沉降问题。
为了表征磁流变液的沉降性能，人们开发了多种磁流变液沉降状态的检测装置，主要有电感/电容法等，它们将磁流变液盛放于竖直放置的玻璃试管内，利用介电常数与磁流变液沉降状态(铁磁颗粒体积分数)之间的关系进行测量。这种方法可以较好的确定从磁流变液液面到底部的沉降状态，但不能应用于磁流变阻尼器等器件内部。随着磁流变阻尼器技术的发展，人们对磁流变液在阻尼器内部的沉降状态提出了在线监测的需求。
发明内容
本发明的目的是解决现有技术中存在的问题。
为实现本发明目的而采用的技术方案是这样的，基于在线监测的抗沉降磁流变阻尼器，主要包括磁流变阻尼器、超声波换能器和处理电路。
所述磁流变阻尼器包括工作缸和实现磁流变液分散的电机。工作缸内装有磁流变液。
所述超声波换能器贴置在工作缸底部的侧壁。
超声波换能器为超声波发射换能器和超声波接收换能器或收发一体的超声波换能器。
超声波发射换能器和超声波接收换能器关于工作缸的中心轴对称。
超声波发射换能器和超声波接收换能器之间的距离记为L。L>0
收发一体的超声波换能器以工作缸正对的缸筒面为反射面，以超声波换能器在反射面的投影为反射点。
收发一体的超声波换能器和反射点的连续过工作缸的中心轴线。
所述超声波换能器的线束连接处理电路。
所述处理电路通过线束接收超声波换能器的接收电压Ex，得到t时刻超声波传播通道的磁流变液分散相体积浓度a t，以下简称磁流变液分散相体积浓度为浓度。
浓度a t满足下式：
a t＝a 0+a x。 (1)
式中，a 0为初始状态浓度。a x为因沉降引起的浓度变化。
初始状态浓度a 0满足下式：
a 0＝(lnE0-lnEr)/L。 (2)
式中，E0为磁流变液初始状态时超声波换能器的接收电压。当磁流变液处于初始状态时的接收电压E0存储在所述处理电路中。E r为磁流变液初始状态时超声波换能器的发射电压。
因沉降引起的浓度变化a x如下所示：
a x＝(lnE0-lnEx)/L。  (3)
式中，若超声波换能器为收发一体超声波换能器，则L为工作缸缸筒直径的两倍。若超声波换能器为超声波发射换能器和超声波 接收换能器，则L为超声波发射换能器和超声波接收换能器之间的距离。
所述处理电路根据式(3)求取沉降浓度变化a x，判断是否需要对磁流变液进行分散。当判断浓度变化a x大于某一阈值k时，则通过处理电路对外输出电激励信号，若否，则不产生电激励信号。磁流变阻尼器基于处理电路输出的电激励信号，驱动电机对磁流变液进行分散。
本发明的技术效果是毋庸置疑的。本发明针对竖向使用的磁流变阻尼器，基于超声波在悬浮液中的传播机理，提出一种基于在线监测的抗沉降磁流变阻尼器，可以实现磁流变阻尼器的磁流变液的自主调控和抗沉降。
附图说明
图1为基于在线监测的抗沉降磁流变阻尼器结构示意图；
图2为磁流变阻尼器结构示意图I；
图3为触发电路图；
图4为LM1812的工作原理图；
图5为变压器其匝数比设置原理图；
图6为磁流变阻尼器结构示意图II；
图7为磁流变阻尼器底盖的结构示意图；
图8为转子的结构示意图；
图9为定子的结构示意图；
图10为顶盖的结构示意图；
图11为工作缸的结构示意图；
图12为处理电路流程图；
图中：液筒12、底盖13、圆环I131、圆盘I132、圆孔I1321、沉头孔1322、定位柱14、通孔II141、转子15、伸出轴151、鼠笼152、螺旋筋肋153、定子16、外筒161、内筒162、通槽II1621、磁极163、绕组164、绕组引线165、顶盖17、台阶圆环171、圆盘II172、圆孔II1721、辐条173、工作缸11、通槽I111、通孔I112、活塞组件18、活塞杆19、磁流变阻尼器1、超声波换能器2、处理电路3和超声波换能器线束21。
具体实施方式
下面结合实施例对本发明作进一步说明，但不应该理解为本发明上述主题范围仅限于下述实施例。在不脱离本发明上述技术思想的情况下，根据本领域普通技术知识和惯用手段，做出各种替换和变更，均应包括在本发明的保护范围内。
实施例1：
参见图1和图2，基于在线监测的抗沉降磁流变阻尼器，主要包括磁流变阻尼器1、超声波换能器2和处理电路3。
所述磁流变阻尼器1包括工作缸11和实现磁流变液分散的电机。工作缸11内装有磁流变液。
磁流变阻尼器1在接收到处理电路3的电激励信号后，驱动电机对磁流变液进行分散。
所述超声波换能器2贴置在工作缸11底部的侧壁。
所述超声波换能器2的线束21延伸出磁流变阻尼器1，并连接处理电路3。
磁流变液沉降在缸筒底部，使分散相具有最高体积分数，超声波换能器位于缸筒底部，紧贴缸筒圆周面进行布置，使声发射方向通过缸筒轴线，当超声波发射器发出特定频率的超声波后，由其对面的超声波接收器接收。
超声波换能器2为超声波发射换能器和超声波接收换能器或收发一体的超声波换能器。
优选的，超声波发射换能器和超声波接收换能器关于工作缸的中心轴对称。
超声波发射换能器和超声波接收换能器之间的距离记为L。L>0
优选的，收发一体的超声波换能器以工作缸正对的缸筒面为反射面，以超声波换能器在反射面的投影为反射点。
收发一体的超声波换能器和反射点的连续过工作缸的中心轴线。当超声波换能器接收到反射回来的超声波信号时，携带了超声波在沉降状态的磁流变液中传播后的衰减信息，通过线束21传输给处理电路进行处理后进行输出。
当磁流变阻尼器处于静置状态时，磁流变液发生沉降，所述处理电路3通过线束21接收超声波换能器2的接收电压Ex，得到t时刻超声波传播通道的磁流变液分散相体积浓度a t。
t时刻磁流变液浓度a t满足下式：
a t＝a 0+a x。 (1)
式中，a 0为磁流变液处于初始状态，即尚未发生沉降的状态时的浓度。若超声波换能器2为收发一体超声波换能器，则L为工作缸11缸筒直径的两倍。若超声波换能器2为超声波发射换能器和超声波接收换能器，则L为超声波发射换能器和超声波接收换能器之间的距离。E0为磁流变液初始状态时超声波换能器2的接收电压。
初始状态浓度a 0满足下式：
a 0＝(lnE0-lnEr)/L。 (2)
式中，E0为磁流变液初始状态时超声波换能器的接收电压。当磁流变液处于初始状态时的接收电压E0存储在所述处理电路中。E r为磁流变液初始状态时超声波换能器的发射电压。
a x为因沉降引起的浓度变化，如下所示：
a x＝(lnE0-lnEx)/L (3)
本实施例采用收发一体超声波探头，并安装于直径为3cm的工作缸筒内时，L＝6cm，可得表格如下：
表1 磁流变液中铁磁颗粒体积浓度变化a x
E0/EX 1 2 3 4 5
a x 0 0.1155 0.1831 0.2310 0.2682
此时将阈值k设置为0.1831时，由于磁流变阻尼器1处于静置状态，则代表因静置沉降导致的浓度变化达到18.31％时，通过处理电路(3)对外输出电激励信号。磁流变阻尼器接收到电激励信号后，驱动电机对磁流变液进行分散。
磁流变阻尼器1得到驱动信号后，在定子旋转磁场的激励下使转子旋转，并在转子外圆面螺线的帮助下，磁流变液可以在阻尼器内部形成流动回路，从而克服磁流变阻尼器长期静置面临的沉降问题。因此，需要对磁流变阻尼器底部的磁流变液沉降状态开展在线监测，从而确立反馈机制，使磁流变阻尼器在长期静置时适时启动电机。
所述处理电路3可以采用LM1812专业集成电路，不仅外围元件较少，电路简单，而且有更好的稳定性及可靠性。超声波集成电路 LM1812芯片内部包括一个脉冲调制C类振荡器，需要一个具有周期性的触发信号来触发电路的时序，本实施例利用555定时器构成占空比一定的多谐振荡器。触发电路如图3所示。该电路中，充电回路和放电回路是相互独立的，是利用电容C11的充电放电来获取方波信号的。充电回路由R3和C11组成，输出高电平。放电回路由R4和C11组成，输出低电平。
LM1812的工作原理如图4所示。1脚外接L1、C1，构成脉冲调制C类振荡器，这决定了发送器和接收器的工作频率，其工作频率可达325kHz，可根据所需要的超声波频率决定L1、C1的值。8脚为发送控制端，与555定时器构成的多谐振荡器的3脚相连，当8脚为高电平时，芯片处于发送模式，此时L1、C1振荡槽路被切换成振荡模式，振荡信号经驱动放大之后，通过13脚和6脚输出，一般6脚、13脚之间要接变压器，以便与超声波发送器阻抗相匹配，以40kHz和200kHz为例，可按图5设置变压器其匝数比。搭建好输出变压器后，应测试6脚电流大小，保证6脚最大电流值不能超过1A。否则可能因电流过大出现过载现象导致芯片损坏。如果实际需要更大的功率，则可以采用外加脉冲放大器的方法来实现所需，输出电流最高可以达到5A。
当8脚为低电平时，LM1812处于接收模式。8脚的输入电流设计在1-10mA范围内。在本实施例设计里，因为LM1812的供电电压为12V，所以选择在8脚加一个10k的电阻。由于超声波信号经过磁流变液传播后，其声波强度衰减很大，回波信号幅值很微弱。采用AD637均方根检波电路分别对超声波的发射和接受信号获取有效值后进行标定，可以获取输出电压与磁流变液浓度之间的关系。
如图12所示，处理电路3调取电压E0和长度L，并获取超声波回波电压值，计算得到磁流变液浓度变化a x，若浓度变化值大于15％-25％，则触发抗沉降磁流变阻尼器的主动分散装置对磁流变液进行分散，分散T时间后，继续监测超声波换能器2。本实施例设定T＝3min。主动分散装置，也即电机，包括抗沉降磁流变阻尼器的定位柱14、转子15和定子16。本实施例设定阈值k的范围为[0.15，0.25]。
实施例2：
参见图6至图11，磁流变阻尼器1主要包括工作缸11、液筒12、底盖13、顶盖17、活塞组件18、活塞杆19和电机。电机包括定位柱14、转子15和定子16。
所述液筒12为中空圆柱体，其下端的敞口处具有螺纹。
所述液筒12与所述底盖13之间通过O型圈进行密封。
所述底盖13的上端为圆环I131。所述圆环I131外壁具有螺纹。所述底盖13的下端为圆盘I132。所述圆盘I132的端面中心具有圆孔I1321。所述圆盘I132的端面上设有处于同一圆周的若干个沉头孔1322。
所述底盖13的上端安装在所述液筒12下端的敞口处。
所述定位柱14安装在所述沉头孔1322的台阶上。
所述定位柱14内部具有通孔II141。所述通孔II141与所述底盖13的沉头孔1322接通。
所述转子15为圆柱体，其两端的端面中心具有伸出轴151。所述转子15内部嵌入有鼠笼152。所述转子15的外圆周壁上设置有螺旋筋肋153。
所述转子15位于所述液筒12内，其下端的伸出轴151支承在所述底盖13的圆孔I1321中。
所述转子15由软磁材料制作。
所述定子16采用硅钢片叠合制成。
所述定子16包括外筒161和内筒162。
所述内筒162位于所述外筒161内部。所述内筒162与所述外筒161之间布置有若干个磁极163。每一个磁极163上均绕制有绕组164。
所述内筒162的内壁上均布有若干个贯穿内筒162两端的通槽II1621。在相邻的磁极163所对应的内筒162的内壁上，均具有一个通槽II1621。
所述定子16外套于所述转子15上，并位于所述液筒12内，其下端固定在所述定位柱14上。
所述定子16与所述转子15之间形成一个内通道。所述定子16与所述液筒12之间形成一个外通道。所述定子16通过定位柱14支承，形成一个接通内通道和外通道的空间。
优选的，所述定子16的绕组引线165通过所述定位柱14上的通孔II141引出，并通过所述沉头孔1322穿出所述底盖13。
所述顶盖17包括台阶圆环171和圆盘II172。
所述圆盘II172位于所述台阶圆环171内，其端面中心具有圆孔II1721。所述圆盘II172通过与所述台阶圆环171之间通过辐条173接连。
所述顶盖17安装在所述定子16的上端。所述转子15上端的伸出轴151支承在所述顶盖17的圆孔II1721中。
所述工作缸11为圆筒状。所述工作缸11的周向均布有若干个通槽I111和若干个通孔I112，其中通槽I111位于所述工作缸11的内圆面，其位置记为平衡位置。
所述工作缸11位于所述液筒12内，其下端套装在所述台阶圆环171的台阶上。所述工作缸11装有磁流变液。
所述活塞组件18位于所述工作缸11内，并与所述工作缸11之间具有间隙。
所述活塞杆19的安装在活塞组件18上，能够推动活塞组件18在工作缸11内做往复运动。
所述绕组164接收到处理电路3的电激励信号后，所述定子16内形成旋转磁场，所述转子15的鼠笼152切割磁力线产生感生电流而受到磁力作用，带动转子15旋转。
当所述转子15转动时，所述螺旋筋肋153带动磁流变液在内通道做旋转流动和轴向流动，并流向外通道。
当所述活塞组件18处于平衡位置时，流向外通道的磁流变液经过所述工作缸11与所述液筒12之间的间隙，通过所述通槽1701和所述通孔I112流入工作缸11内部，当所述活塞组件18脱离平衡位置做上下往复运动时，流向外通道的磁流变液经过所述工作缸11与所述液筒12之间的间隙，通过所述通孔I112流入工作缸11内部，形成流动回路，从而实现有效的磁流变液再分散作用。
当磁流变阻尼器正常运行时，此时可以改变定子16内绕组164的励磁方式，使其生成均一同向的磁场分布，将使内通道内充满一致均匀的磁场，从而有效调控活塞组件8运行时的磁流变阻尼力。
优选的，所述转子15两端的伸出轴151通过滚动轴承或者轴套 支承，轴套采用聚四氟乙烯制作，便于减少两端的伸出轴151与顶盖17和底盖13的摩擦。

Claims (4)

  1. 基于在线监测的抗沉降磁流变阻尼器，其特征在于，主要包括磁流变阻尼器(1)、超声波换能器(2)和所述处理电路(3)。
    所述磁流变阻尼器(1)具有工作缸(11)；工作缸(11)内装有磁流变液；
    所述超声波换能器(2)贴置在工作缸(11)底部的侧壁；
    所述超声波换能器(2)的线束(21)连接处理电路(3)；
    所述处理电路(3)通过线束(21)接收超声波换能器(2)的接收电压Ex，得到t时刻超声波传播通道的磁流变液分散相体积浓度a t；
    浓度a t满足下式：
    a t＝a 0+a x；    (1)
    式中，a 0为初始状态浓度；a x为因沉降引起的浓度变化；
    初始状态浓度a 0满足下式：
    a 0＝(lnE0-lnEr)/L；    (2)
    式中，E0为磁流变液初始状态时超声波换能器(2)的接收电压；当磁流变液处于初始状态时的接收电压E0存储在所述处理电路(3)中；E r为磁流变液初始状态时超声波换能器(2)的发射电压；因沉降引起的浓度变化a x如下所示：
    a x＝(lnE0-lnEx)/L；    (3)
    式中，若超声波换能器(2)为收发一体超声波换能器，则L为工作缸(11)缸筒直径的两倍；若超声波换能器(2)为超声波发射换能器和超声波接收换能器，则L为超声波发射换能器和超声波接收换能器之间的距离；
    所述处理电路(3)根据式(3)求取的沉降浓度变化a x，判断是否对需要对磁流变液进行分散，若需要，则产生电激励信号，并传递至磁流变阻尼器(1)。
  2. 根据权利要求1所述的基于在线监测的抗沉降磁流变阻尼器，其特征在于：超声波换能器(2)为超声波发射换能器和超声波接收换能器或收发一体的超声波换能器。
    超声波发射换能器和超声波接收换能器关于工作缸(11)的中心轴对称；
    超声波发射换能器和超声波接收换能器之间的距离记为L；L>0
    收发一体的超声波换能器以工作缸(11)正对的缸筒面为反射面，以超声波换能器在反射面的投影为反射点；
    收发一体的超声波换能器和反射点的连线过工作缸(11)的中心轴线。
  3. 根据权利要求1或2所述的基于在线监测的抗沉降磁流变阻尼器，其特征在于，处理电路(3)产生电激励信号的方法为：判断浓度变化a x是否大于阈值k，若是，则通过处理电路(3)对外输出电激励信号，若否，则不产生电激励信号。
  4. 根据权利要求3所述的基于在线监测的抗沉降磁流变阻尼器，其特征在于：磁流变阻尼器(1)还包括实现磁流变液分散的电机；磁流变阻尼器(1)在接收到处理电路(3)的电激励信号后，驱动电机对磁流变液进行分散。
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CN111578895B (zh) * 2020-04-21 2022-04-01 重庆大学 一种磁流变阻尼器件内部磁流变液的沉降监测方法
CN113606276B (zh) * 2021-08-12 2022-06-21 重庆大学 圆周阵列螺旋槽活塞防沉降磁流变阻尼器
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