Acceleration sensor based on conductive magnetorheological elastomer

Abstract

The invention relates to the technical field of acceleration measurement, and particularly discloses an acceleration sensor based on a conductive magnetorheological elastomer, and the acceleration sensor comprises a housing which is provided with a sealed cavity, and the sealed cavity is filled with ferrofluid; the permanent magnet is arranged in the sealing cavity and connected with the inner wall of the shell through an elastic supporting piece so that the permanent magnet can be suspended in the ferrofluid; and the conductive magnetorheological elastomer is installed in the sealing cavity, the central axis of the conductive magnetorheological elastomer coincides with the central axis of the permanent magnet, and a first electrode and a second electrode are arranged on the two sides of the conductive magnetorheological elastomer respectively and connected with the positive electrode wiring terminal and the negative electrode wiring terminal respectively. The acceleration sensor is simple in structure, wide in frequency response range and complete in measurement information, and efficient conversion and measurement of acceleration signals are achieved through the magnetic response characteristic of the ferrofluid and the high-sensitivity sensing capacity of the conductive magnetorheological elastomer.

Description

Technical Field

[0001] This invention relates to the field of acceleration measurement technology, and in particular to an acceleration sensor based on a conductive electromagnetic rheoelastic elastomer. Background Technology

[0002] Accelerometers are core sensing components in modern industry and high-end equipment, and their performance directly affects the accuracy and reliability of dynamic measurements. While traditional accelerometers such as piezoelectric and resistance strain gauge sensors are technologically mature, they have certain limitations. For example, piezoelectric sensors cannot measure static acceleration and have poor low-frequency response; resistance strain gauge sensors are limited by their low response frequency, making them unsuitable for high-frequency dynamic range measurement scenarios.

[0003] Compared to traditional accelerometers, ferrofluidic accelerometers offer advantages such as low frictional loss, wide dynamic measurement range, and high sensitivity. While significant progress has been made in the application of ferrofluids in accelerometers, previous ferrofluidic accelerometers often employed inductive or transformer-type coils as their sensing elements. These coils were generally large and heavy, resulting in lower natural frequencies. Some ferrofluidic accelerometers also used Hall effect sensors to detect magnetic field changes. While this facilitated miniaturization, it neglected the coupling between the fluid pressure and magnetic field changes, leading to incomplete measurement information. Summary of the Invention

[0004] Based on this, the purpose of this invention is to provide an acceleration sensor based on a conductive electromagnetic rheotropic elastomer, which achieves efficient conversion and measurement of acceleration signals by utilizing the magnetic response characteristics of ferrofluids and the high sensitivity sensing capability of conductive electromagnetic rheotropic elastomers.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides an acceleration sensor based on a conductive rheotropic elastomer, comprising: The outer casing has a sealed cavity filled with a ferrofluid. A permanent magnet, disposed within the sealed cavity, is connected to the inner wall of the outer shell via an elastic support to suspend it in the ferrofluid; and The testing component is installed on the inner wall of the housing. It includes a conductive rheo-elastic body and a first electrode and a second electrode disposed on both sides of the conductive rheo-elastic body. The first electrode and the second electrode are respectively connected to a positive terminal and a negative terminal.

[0006] As a further improvement to the above-mentioned solution of the present invention, the first electrode and the second electrode are symmetrically arranged about the electromagnetic rheo-elastic body, and the central axis of the first electrode and the second electrode coincides with the central axis of the electromagnetic rheo-elastic body.

[0007] As a further improvement to the above-mentioned solution of the present invention, the first electrode and the second electrode are prepared by silver paste printing process.

[0008] As a further improvement of the above-mentioned solution of the present invention, the detection component also includes a sealing shell, which is installed on the inner wall of the outer shell. The sealing shell has a sealed mounting cavity, and the conductive electromagnetic rheodynamic elastomer, the first electrode, and the second electrode are all disposed in the mounting cavity. The positive terminal and the negative terminal extend out of the sealing shell.

[0009] As a further improvement to the above-mentioned solution of the present invention, the elastic support includes a spring sheet, which is fixed on the inner wall of the outer shell and has a cantilever. The end of the cantilever away from the spring sheet is a free end, and a permanent magnet is installed on the free end of the cantilever.

[0010] As a further improvement to the above-mentioned solution of the present invention, the number of permanent magnets is two, and the two permanent magnets are symmetrically installed on the cantilever, with the central axis of the two permanent magnets coinciding with the central axis of the spring sheet.

[0011] As a further improvement to the above-mentioned solution of the present invention, a support platform is provided at the free end of the cantilever, and two permanent magnets are respectively installed on both sides of the support platform, and the shape and size of the two permanent magnets are consistent with the shape and size of the support platform.

[0012] As a further improvement to the above-mentioned solution of the present invention, the permanent magnet does not contact the inner wall of the outer shell.

[0013] As a further improvement to the above-mentioned solution of the present invention, the outer periphery of the conductive electromagnetic rheotropic elastomer is wrapped with an insulating sealing layer, the insulating sealing layer extending to the edges of the first electrode and the second electrode and covering the roots of the positive terminal and the negative terminal.

[0014] As a further improvement to the above-mentioned solution of the present invention, both the inner surface of the outer shell and the outer surface of the sealing shell are provided with a low-viscosity coating.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention provides an accelerometer based on a magnetically conductive magnetorheological elastomer (MTE). The MTE possesses unique magnetoelectric and mechanoelectric properties. When a permanent magnet vibrates and displaces due to acceleration excitation, the MTE can sense changes in magnetic field strength and capture the minute pressure exerted by a ferrofluid on the MTE, supplementing information easily overlooked during magnetic field detection. The MTE can function as a variable arm resistor in a Wheatstone bridge, connected to the detection circuit via positive and negative terminals. The MTE converts changes in magnetic field and pressure into changes in resistance. The detection circuit outputs a voltage signal based on the resistance change of the MTE, from which acceleration information can be calculated. The proposed accelerometer features a simple structure, wide frequency response range, and complete measurement information. By combining the magnetic response characteristics of the ferrofluid with the high sensitivity of the MTE, efficient conversion and measurement of acceleration signals are achieved.

[0016] In this invention, the conductive electromagnetic rheotropic elastomer changes its resistivity through structural changes induced by a magnetic field. It is a passive magnetic response that does not rely on carrier deflection and is more suitable for detecting dynamic changes in magnetic fields under vibration environments.

[0017] In the detection device of this invention, symmetrically distributed sheet-like conductive electrodes are designed on the surface of a conductive magnetorheological elastomer: the first electrode and the second electrode, made of silver paste, can be tightly bonded to the magnetorheological elastomer through a printing process, avoiding contact resistance fluctuations under vibration and ensuring stable conversion of resistance changes to voltage changes. The first electrode leads out the voltage of the magnetorheological elastomer, and the second electrode is connected to the excitation current of a constant current source. The resistivity change is converted into a measurable voltage signal by the detection circuit, and the acceleration measurement result can be obtained by the signal processing module of the detection circuit. In addition, the symmetrical sheet-like electrodes ensure a uniform electric field distribution, minimizing the linearity error between the resistivity change and the magnetic field change of the magnetorheological elastomer. Attached Figure Description

[0018] Figure 1 An external view of an accelerometer based on a conductive electromagnetic rheoelastic body provided in an embodiment of the present invention; Figure 2 An internal structure diagram of an accelerometer based on a conductive electromagnetic rheoelastic body is provided for an embodiment of the present invention. Figure 3 An external view of the detection element in an accelerometer based on a conductive electromagnetic rheoelastic body, provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the internal structure of the detection element in an accelerometer based on a conductive electromagnetic rheotropic elastomer, provided in an embodiment of the present invention. Figure 5This is a schematic diagram illustrating the working principle of an acceleration sensor based on a conductive electromagnetic rheoelastic body, provided for an embodiment of the present invention.

[0019] Reference numerals in the attached drawings: 1. Outer shell; 1-1. Sealed cavity; 1-2. Shell one; 1-3. End cap one; 2. Permanent magnet; 3. Detection component; 3-1. Electromagnetic rheotropic elastomer; 3-2. First electrode; 3-3. Second electrode; 3-4. Positive terminal; 3-5. Negative terminal; 3-6. Sealed shell; 3-61. Shell two; 3-62. End cap two; 4. Spring plate; 4-1. Cantilever; 4-2. Support platform. Detailed Implementation

[0020] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0022] Reference Figure 1-2 This embodiment proposes an acceleration sensor based on a conductive electromagnetic rheoelastic body, which includes a housing 1, a permanent magnet 2, and a detection element 3.

[0023] The outer casing 1 consists of a housing 1-2 and an end cap 1-3. One end of the housing 1-2 is open, and the end cap 1-3 is detachably connected to the open end of the housing 1-2 by stainless steel screws to form a sealed cavity 1-1 between the housing 1-2 and the end cap 1-3. The sealed cavity 1-1 is filled with ferrofluid. To facilitate subsequent filling of the ferrofluid, an injection hole for injecting the ferrofluid needs to be made on the housing 1-2. To reduce the adhesion effect between the ferrofluid and the inner wall of the outer casing 1, a low-viscosity coating needs to be formed on the inner surfaces of the housing 1-2 and the end cap 1-3, for example, by spraying a material (e.g., perfluoropolyether) onto the inner surfaces of the housing 1-2 and the end cap 1-3 to form the low-viscosity coating.

[0024] The permanent magnet 2 is disposed within the sealed cavity 1-1 of the outer shell 1. The permanent magnet 2 is connected to the inner wall of the outer shell 1 via an elastic support to suspend it in the ferrofluid. In this embodiment, the elastic support includes a spring plate 4, which is fixed to the inner wall of the outer shell 1 and integrally formed with a cantilever 4-1. The end of the cantilever 4-1 away from the spring plate 4 is a free end, and a load-bearing platform 4-2 is integrally formed at the free end of the cantilever 4-1. There are two permanent magnets 2, and the shape and size of the two permanent magnets 2 are consistent with the shape and size of the load-bearing platform. The two permanent magnets 2 are symmetrically magnetically attracted and fixed on the load-bearing platform 4-2, and the central axis of the two permanent magnets 2 coincides with the central axis of the spring plate 4. The weighing platform 4-2 is identical in shape and size to the permanent magnets 2, so that during actual installation, the permanent magnets 2 can be magnetically attracted and fixed relatively stably on the cantilever 4-1 of the spring plate 4, avoiding the risk of the permanent magnets 2 falling off arbitrarily during vibration of the accelerometer device.

[0025] Permanent magnet 2 is the magnetic field generating unit. When a certain acceleration excitation is applied from the outside, the magnetic field generating unit will generate relative displacement under the action of inertial force. This relative displacement will cause the magnetic field around the two permanent magnets 2 to change. It should be noted that the ferrofluid is used as a damping medium. The filling amount of ferrofluid in the sealed cavity 1-1 should be sufficient to completely submerge the spring plate 4 and the two permanent magnets 2, so that the permanent magnets 2 can be completely suspended in the ferrofluid. The ferrofluid provides a restoring force to the two permanent magnets 2 through its own suspension effect. The permanent magnets 2 will be stably suspended in the ferrofluid under the action of the second-order buoyancy of the ferrofluid. Since the surface of the permanent magnets is saturated with ferrofluid, based on the buoyancy principle of ferrofluid, it can also effectively avoid contact and collision with the detection element 3 and the housing 1-2. At the same time, the ferrofluid also has good lubricity, which can increase the range and sensitivity of the accelerometer and effectively improve the service life of the accelerometer.

[0026] Detection component 3 is installed on the inner wall of the outer casing 1. Detection component 3 is the core part of the entire device. Figure 3-4The detection component 3 is designed as a thin-film sandwich structure, including a sealing shell 3-6, an electromagnetic rheodynamic elastomer 3-1, a first electrode 3-2, and a second electrode 3-3. The sealing shell 3-6 is fixed to a predetermined position on the inner wall of the outer shell 1. The sealing shell 3-6 consists of a shell 3-61 and an end cap 3-62. One end of the shell 3-61 is open, and the end cap 3-62 is detachably connected to the open end of the shell 3-61 via stainless steel screws, forming a sealed mounting cavity between the shell 3-61 and the end cap 3-62. The electromagnetic rheodynamic elastomer 3-1 is placed within the mounting cavity, and its central axis must coincide with the central axes of the two permanent magnets 2. The first electrode 3-2 and the second electrode 3-3 are respectively disposed on the two side surfaces of the electromagnetic rheodynamic elastomer 3-1. In this embodiment, a first electrode 3-2 and a second electrode 3-3 are respectively fabricated on the upper and lower surfaces of the electromagnetic rheo-elastic body 3-1 using a silver paste printing process. The first electrode 3-2 and the second electrode 3-3 are symmetrically arranged about the electromagnetic rheo-elastic body 3-1, and the central axis of the first electrode 3-2 and the second electrode 3-3 coincides with the central axis of the electromagnetic rheo-elastic body 3-1. The first electrode 3-2 and the second electrode 3-3 form a uniform electric field, and the direction of the electric field generated by the first electrode 3-2 and the second electrode 3-3 is perpendicular to the surface of the electromagnetic rheo-elastic body 3-1 and is consistent with the direction of the magnetic field generated by the permanent magnet 2, ensuring that the overall resistivity change of the electromagnetic rheo-elastic body 3-1 is completely collected. A lead wire hole of predetermined specifications is designed on the side of the first electrode 3-2 on the sealing shell 3-6, and a lead wire hole of predetermined specifications is designed on the side of the second electrode 3-3 on the sealing shell 3-6. The first electrode 3-2 and the second electrode 3-3 are respectively connected to a positive terminal 3-4 and a negative terminal 3-5. The positive terminal 3-4 and the negative terminal 3-5 are exposed through the lead wire hole one and the lead wire hole two, respectively, and can be connected to the circuit normally.

[0027] The core of the detection component 3 is a conductive electromagnetic rheo-elastic body 3-1. This 3-1 acts as a variable arm resistor in a Wheatstone bridge, connected to the detection circuit via positive terminal 3-4 and negative terminal 3-5. The 3-1 possesses unique magnetoelectric and mechanical properties. When the two permanent magnets in the accelerometer vibrate vertically due to acceleration, the 3-1 can not only sense changes in magnetic field strength but also detect the fluid pressure of the ferrofluid. The 3-1 converts the detected magnetic field change into a resistance change and the detected pressure change into a resistance change, with the signal processing module of the detection circuit outputting a voltage signal.

[0028] It should be noted that, in order to ensure the long-term stability and reliability of the detection component 3 in the actual working environment, effective side sealing of the conductive electromagnetic rheodynamic elastomer 3-1 is required. In this embodiment, without changing the structural layout of the detection component 3, the conductive electromagnetic rheodynamic elastomer 3-1 is edge-encapsulated around its perimeter after assembly. Specifically, a highly insulating and flexible encapsulating material (such as commercially available two-component room temperature vulcanizing (RTV) silicone potting compound) is used, and a precise coating process is employed to form a continuous, closed insulating sealing layer along the outer edges of the first electrode 3-2 and the second electrode 3-3, thereby completely encapsulating the conductive electromagnetic rheodynamic elastomer 3-1. The insulating sealing layer also covers the root areas of the positive terminal 3-4 and the negative terminal 3-5, with electrical connection ports reserved only at the ends, thus achieving a coordinated design of sealing and conductive path.

[0029] Similarly, in order to reduce the adhesion effect between the ferrofluid and the wall of the sealing shell 3-6, a low-viscosity coating needs to be formed on the outer surface of the shell 3-61 and the end cap 3-62, for example by spraying a material (e.g., perfluoropolyether) on the outer surface of the shell 3-61 and the end cap 3-62 to form a low-viscosity coating.

[0030] When assembling the accelerometer sensor in this embodiment, all components to be assembled need to be cleaned to remove oil, dust and other impurities adhering to the surface. At the same time, it is necessary to ensure that the assembly environment is clean and free of pollution, and it is best to install it in a sterile environment.

[0031] During assembly, first, place the two permanent magnets 2 on the upper and lower surfaces of the support platform 4-2 of the cantilever 4-1 of the spring plate 4, ensuring that the central axis of the two permanent magnets 2 coincides with the central axis of the spring plate 4. Next, install the spring plate 4 in the preset position inside the housing 1-2. The detection component 3 is fixed to the preset installation position inside the housing 1-2 using fasteners or adhesive. The central axis of the conductive electrorheological elastomer 3-1 must coincide with the central axis of the permanent magnet 2. The signal leads of the positive terminal 3-4 and the negative terminal 3-5 must be led out and fixed according to the preset path. The lead arrangement must avoid entanglement and interference, while ensuring the stability of the connection with the detection component 3 to guarantee subsequent signal transmission. Use stainless steel screws to completely seal the end cap 1-3 to the upper part of the housing 1-2. Then, slowly inject ferromagnetic fluid from the pre-reserved injection hole on the housing 1-2. The filling amount should be sufficient to completely submerge the spring plate 4 and the two permanent magnets 2, allowing the two permanent magnets 2 to be completely suspended in the ferromagnetic fluid. The injection process requires flow rate control to prevent bubble formation. If bubbles appear during operation, a degassing process must be used to remove them promptly. After the ferromagnetic fluid injection is completed, the injection hole can be sealed using existing conventional methods: First, machine a matching internal thread on the inner wall of the injection hole. After completing the ferromagnetic fluid injection, select a PTFE threaded plug that matches the thread of the injection hole. Apply a layer of anaerobic sealant evenly to the threaded surface of the plug. Slowly insert the plug into the injection hole and tighten it. Let it stand for 1-2 hours to allow the sealant to cure at room temperature, thus completing the sealing of the injection hole.

[0032] The acceleration sensor provided in this embodiment can be adapted to various scenarios that require acceleration monitoring. It can be used in industrial equipment condition monitoring scenarios; it can also be used in vehicle vibration monitoring scenarios, and can be mounted on the surface of components such as automobile engines and rail transit bogies; as well as in intelligent robot motion control scenarios, such as monitoring the acceleration of joint movements in industrial robotic arms.

[0033] Combination Figure 5Taking an electromagnetic vibration table as an example, the working principle of the accelerometer in this embodiment is explained as follows: The accelerometer in this embodiment can be fixed to the electromagnetic vibration table using fasteners (such as screws) or by adhesive. The conductive electrorheological elastomer 3-1 is connected to the detection circuit as a variable arm resistor of a Wheatstone bridge via the positive terminal 3-4 and the negative terminal 3-5. When a certain acceleration excitation is input to the electromagnetic vibration table, the permanent magnet 2 will generate relative displacement under the action of inertial force. This displacement will change the magnetic field strength around the two permanent magnets 2, and will also transmit fluid pressure to the detection element 3 through the ferrofluid. Under the dual action of magnetic field and pressure, the distribution state of the conductive magnetic particles inside the core component of the detection element 3, the conductive electrorheological elastomer 3-1, changes, leading to a corresponding change in its resistivity. The detection circuit converts the resistivity change into a measurable voltage signal, and the acceleration measurement result can be obtained through the signal processing module of the detection circuit. It should be noted that the detection circuit and signal processing module mentioned here are based on existing mature technology principles and will not be elaborated further here.

[0034] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0037] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An accelerometer based on a conductive electromagnetic rheoelastic body, characterized in that, It includes: The outer casing (1) has a sealed cavity (1-1) filled with a ferrofluid; A permanent magnet (2), disposed within the sealed cavity (1-1), is connected to the inner wall of the outer shell (1) via an elastic support to suspend it in the ferrofluid; and The detection component (3) is installed on the inner wall of the outer shell (1). It includes a conductive rheodynamic elastomer (3-1) and a first electrode (3-2) and a second electrode (3-3) disposed on both sides of the conductive rheodynamic elastomer (3-1). The first electrode (3-2) and the second electrode (3-3) are respectively connected to a positive terminal (3-4) and a negative terminal (3-5).

2. The accelerometer based on a conductive electromagnetic rheoelastic body according to claim 1, characterized in that, The first electrode (3-2) and the second electrode (3-3) are symmetrically arranged about the conductive electromagnetic rheoelastic body (3-1), and the central axis of the first electrode (3-2) and the second electrode (3-3) coincides with the central axis of the conductive electromagnetic rheoelastic body (3-1).

3. The accelerometer based on a conductive electromagnetic rheoelastic body according to claim 1, characterized in that, The first electrode (3-2) and the second electrode (3-3) were prepared using a silver paste printing process.

4. The accelerometer based on a conductive electromagnetic rheoelastic body according to claim 1, characterized in that, The testing component (3) also includes a sealing shell (3-6), which is installed on the inner wall of the outer shell (1). The sealing shell (3-6) has a sealed mounting cavity. The electromagnetic rheodynamic elastomer (3-1), the first electrode (3-2), and the second electrode (3-3) are all located in the mounting cavity. The positive terminal (3-4) and the negative terminal (3-5) extend out of the sealing shell (3-6).

5. The accelerometer based on a conductive electromagnetic rheoelastic body according to claim 1, characterized in that, The elastic support includes a spring plate (4), which is fixed on the inner wall of the outer shell (1) and has a cantilever (4-1). The end of the cantilever (4-1) away from the spring plate (4) is a free end, and a permanent magnet (2) is installed on the free end of the cantilever (4-1).

6. The accelerometer based on a conductive electromagnetic rheoelastic body according to claim 5, characterized in that, There are two permanent magnets (2), and the two permanent magnets (2) are symmetrically installed on the cantilever (4-1). The central axis of the two permanent magnets (2) coincides with the central axis of the spring plate (4).

7. The accelerometer based on a conductive electromagnetic rheoelastic body according to claim 6, characterized in that, The free end of the cantilever (4-1) is provided with a support platform (4-2), and two permanent magnets (2) are respectively installed on both sides of the support platform (4-2), and the shape and size of the two permanent magnets (2) are consistent with the shape and size of the support platform.

8. The accelerometer based on a conductive electromagnetic rheoelastic body according to claim 1, characterized in that, The permanent magnet (2) does not contact the inner wall of the outer shell (1).

9. The accelerometer based on a conductive electromagnetic rheoelastic body according to claim 1, characterized in that, The outer periphery of the conductive electromagnetic elastomer (3-1) is wrapped with an insulating sealing layer that extends to the edges of the first electrode (3-2) and the second electrode (3-3) and covers the roots of the positive terminal (3-4) and the negative terminal (3-5).

10. The accelerometer based on a conductive electromagnetic rheoelastic body according to claim 4, characterized in that, The inner surface of the outer shell (1) and the outer surface of the sealing shell (3-6) are both provided with a low-viscosity coating.

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