CN110244075B - Gear type magnetic fluid rotating speed sensor and manufacturing method thereof - Google Patents
Gear type magnetic fluid rotating speed sensor and manufacturing method thereof Download PDFInfo
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- CN110244075B CN110244075B CN201910452822.6A CN201910452822A CN110244075B CN 110244075 B CN110244075 B CN 110244075B CN 201910452822 A CN201910452822 A CN 201910452822A CN 110244075 B CN110244075 B CN 110244075B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/42—Devices characterised by the use of electric or magnetic means
- G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
- G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
- G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
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Abstract
The invention discloses a gear type magnetic fluid rotating speed sensor and a manufacturing method thereof, wherein the gear type magnetic fluid rotating speed sensor comprises: the device comprises a shell, a gear, a plurality of induction electrodes and a plurality of magnetic sources; the shell is provided with a cavity, and the gear is arranged in the cavity and can rotate in the cavity; the induction electrode is arranged on the inner wall of the shell, a gap is formed between the induction electrode and the tooth end of the gear, and the magnetic source is arranged on the inner wall of the shell and used for providing a magnetic field at the gap; the cavity is filled with magnetic fluid. The gear type magnetic fluid rotating speed sensor has a simple and compact structure, and each part is relatively independent, so that the gear type magnetic fluid rotating speed sensor is convenient to maintain and overhaul. And the magnetic fluid self-characteristics are utilized, so that the magnetic fluid can adapt to the rotation speed measurement under the high-speed rotation condition.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to a gear type magnetic fluid rotating speed sensor and a manufacturing method thereof.
Background
The rotation speed sensor is a sensor that converts the rotation speed of a rotating object into an electric quantity output. The common rotation speed sensor includes photoelectric type, capacitance type, variable reluctance type, tachogenerator and the like. In the prior art, since the rotation speed sensor performs rotation speed measurement by directly transmitting rotation state, precise micromachining is required to manufacture a sensor core component, a complex microstructure is required in manufacturing, and the processing cost is usually very high.
Accordingly, the prior art is still in need of improvement and development.
Disclosure of Invention
The invention aims to solve the technical problems of the prior art, provides a gear type magnetic fluid rotating speed sensor and a manufacturing method thereof, and aims to solve the problem of high cost caused by complex microstructure of the rotating speed sensor in the prior art.
The technical scheme adopted for solving the technical problems is as follows:
a gear type magnetic fluid rotation speed sensor, comprising: the device comprises a shell, a gear, a plurality of induction electrodes and a plurality of magnetic sources; the shell is provided with a cavity, and the gear is arranged in the cavity and can rotate in the cavity; the induction electrode is arranged on the inner wall of the shell, a gap is formed between the induction electrode and the tooth end of the gear, and the magnetic source is arranged on the inner wall of the shell and used for providing a magnetic field at the gap; the cavity is filled with magnetic fluid.
The gear type magnetic fluid rotating speed sensor comprises a plurality of non-magnetic conductive particles, wherein the non-magnetic conductive particles are used for self-assembling in a magnetic field to connect the induction electrode and the tooth end of the gear, and the width of a gap is 10-10000 mu m.
The gear type magnetic fluid rotating speed sensor is characterized in that the non-magnetic conductive particles are one or more of nanoscale copper powder, nanoscale aluminum powder, nanoscale silver powder, nanoscale copper wire, nanoscale aluminum wire, nanoscale silver wire and fullerene.
The gear type magnetic fluid rotating speed sensor is characterized in that the strength of the magnetic field is larger than 0.1 Tesla.
The gear type magnetic fluid rotating speed sensor is characterized in that a magnetic fluid liquid level probe for detecting the liquid level of magnetic fluid is arranged on the shell.
The gear type magnetic fluid rotating speed sensor is characterized in that the gear is a conical gear.
The gear type magnetic fluid rotating speed sensor is characterized in that one end of the gear is rotatably connected with the inner wall of the shell through a bearing, a gear column is arranged at the other end of the gear, a column hole is formed in the shell, and the gear column penetrates through the column hole to the outside of the cavity.
The gear type magnetic fluid rotating speed sensor is characterized in that a sealing magnet is arranged on the inner wall of the shell, and the sealing magnet surrounds the gear column.
The gear type magnetic fluid rotating speed sensor is characterized in that the gears and the gear columns are not magnetic and can conduct electricity.
A method for manufacturing a gear type magnetic fluid rotation speed sensor based on any one of the above, wherein the method comprises the following steps:
preparing magnetic fluid according to the non-magnetic conductive particles;
the position of the induction electrode, the number of teeth of the gear, the width of the gap and the intensity of the magnetic field are set according to the rotating speed of the gear.
The beneficial effects are that: the gear type magnetic fluid rotating speed sensor has a simple and compact structure, and each part is relatively independent, so that the gear type magnetic fluid rotating speed sensor is convenient to maintain and overhaul. And the magnetic fluid self-characteristics are utilized, so that the magnetic fluid can adapt to the rotation speed measurement under the high-speed rotation condition.
Drawings
Fig. 1 is a partial cross-sectional view of a gear-type magnetic fluid rotational speed sensor according to the present invention.
Fig. 2 is a cross-sectional view of a gear-type magnetic fluid rotational speed sensor according to the present invention.
Fig. 3 is an enlarged view at a in fig. 2.
Fig. 4 is a schematic view of the gear type magnetic fluid rotation speed sensor according to the present invention.
Fig. 5 is a schematic view of the structure of the gear and the gear post of the present invention.
Fig. 6 is a schematic structural view of the cover body in the present invention.
FIG. 7 is a schematic diagram of the structure of the sensing electrode, the magnetic source and the output terminal according to the present invention.
FIG. 8 is a schematic diagram of the structure of a nonmagnetic conductive particle in the present invention without an externally applied magnetic field.
Fig. 9 is a schematic diagram of the structure of non-magnetic conductive particles in a vertical magnetic field in the present invention.
Fig. 10 is a photograph of non-magnetic conductive particles in a vertical magnetic field in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clear and clear, the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1-9, the present invention provides some preferred embodiments of a gear type magnetic fluid rotation speed sensor.
As shown in fig. 1 and 2, the gear-type magnetic fluid rotation speed sensor of the present invention includes: the device comprises a shell 10, a gear 20, a plurality of induction electrodes 30 and a plurality of magnetic sources 40; the housing 10 has a cavity, and the gear 20 is disposed in the cavity and is rotatable therein; the sensing electrode 30 is disposed on the inner wall of the housing 10 with a gap between the sensing electrode 30 and the tooth end of the gear 20, and the magnetic source 40 is disposed on the inner wall of the housing 10 and is used for providing a magnetic field at the gap.
Specifically, the inner wall of the housing 10 is provided with an induction electrode mounting hole, the induction electrode 30 is mounted in the induction electrode mounting hole, and the induction head of the induction electrode 30 extends out of the induction electrode mounting hole, that is, the induction head of the induction electrode 30 extends into the cavity. The cavity is filled with a magnetic fluid (not shown).
The magnetic fluid comprises a plurality of non-magnetic conductive particles which are used for self-assembly in the magnetic field to connect the induction electrode 30 and the tooth end of the gear 20.
It should be noted that the rotation speed of the gear 20 needs to be measured in the present invention. The non-magnetic conductive particles in the magnetic fluid can self-assemble along the direction of the magnetic induction line under the action of a certain magnetic field to form a chain-shaped structure, namely the non-magnetic conductive particles are sequentially arranged and connected into a chain. The gear 20 includes: the gear body 22 and the plurality of teeth 23 arranged on the gear body 22 have concave parts between the adjacent teeth 23, wherein the tooth end of the gear 20 specifically refers to the end of the teeth 23 far from the center of the gear 20 (the gear body 22).
When the gear 20 rotates and the teeth are opposite to the sensing electrode 30, the gap between the teeth end and the sensing electrode 30 is smaller, and two ends of the chain structure formed by connecting the non-magnetic conductive particles are respectively connected to the teeth ends of the sensing motor and the gear 20, so that the conduction between the sensing electrode 30 and the teeth ends of the gear 20 is realized. When the gear 20 rotates and the teeth 23 are not opposite to the sensing electrode 30 (i.e. the concave portion is opposite to the sensing electrode 30), the sensing electrode 30 is far away from the gear 20, and two ends of the chain-shaped structure formed by connecting the non-magnetic conductive particles cannot be connected to the sensing electrode 30 and the gear 20, and certainly, the conduction between the sensing electrode 30 and the gear 20 (i.e. the disconnection between the sensing electrode 30 and the gear 20) cannot be achieved. The rotational speed of the gear 20 can be calculated by sensing the on-off speed of the electrode 30 and the gear 20.
The magnetic fluid is a stable solution formed by mixing nanoscale magnetic particles (magnetic particles, MPs, about 10nm in diameter), a base carrier liquid and a dispersing agent. Compared with the common fluid, the magnetic fluid not only has the fluidity of the liquid, but also has magnetization property, and the magnetic fluid can be controlled by an external magnetic field by utilizing the magnetization characteristic of the magnetic fluid.
The magnetic fluid containing non-magnetic particles is called a antimagnetic fluid (inverse magnetic fluid). This is because the size of the non-magnetic particles is much larger than the nanoscale magnetic particles in the magnetic fluid, and the interaction between the non-magnetic particles and the magnetic fluid can be seen as a fluid-solid coupling between the solid phase particles and the newtonian fluid. Referring to fig. 8-10, with an applied magnetic field, the non-magnetic particles are reverse magnetized by the nearby magnetic fluid and exhibit anisotropy. When a large number of non-magnetic particles are placed in the magnetic fluid, dipole force exists between the non-magnetic particles due to magnetic moment, and the non-magnetic particles are assembled into a chain-shaped structure in the direction of a magnetic field due to the anisotropy. The non-magnetic particles have lower energy and are more stable after being assembled into a chain structure.
In addition, the invention adopts temperature-sensitive insulating magnetic fluid, the common temperature-sensitive insulating magnetic fluid is water-based, oil-based, ester-based, fluoroether oil and other magnetic fluid, and concretely, the base carrier fluid can be water, engine oil, hydroxy-based oil, fluoroether oil and the like, and the dispersing agent can be styrene or phosphate buffer solution for keeping the uniform mixing state of non-magnetic conductive particles. The gear type magnetic fluid rotating speed sensor has better heat radiation performance because the temperature sensing insulating magnetic fluid generally has good heat conductivity.
For ease of calculation, let the number of teeth of the gear 20 be n, the rotational speed of the gear 20 can be calculated in a number of ways: first, when one sensing electrode 30 is provided, the sensing electrode 30 is detected to be on-off with the gear 20 n times for t times 1 Second, thenThe rotation speed of the gear 20 is n/t 1 Revolutions per second. Second, when one sensing electrode 30 is arranged, the time for detecting the on-off of the sensing electrode 30 and the gear 20 adjacent to each other is t 2 Second, the rotation speed of the gear 20 is 1/t 2 Revolutions per second. Third, when two sensing electrodes 30 are provided, the central angle of the two sensing electrodes 30 is α, and the time for detecting that one tooth end sequentially rotates through the two sensing electrodes 30 is t 3 Second, the rotation speed of the gear 20 is t 3 X 360 °/α revolutions per second.
Referring to fig. 1, 2 and 7, in the preferred embodiment of the present invention, an induction electrode 30 and a magnetic source 40 are used, and the magnetic source 40 is a permanent magnet or an electromagnet. In order to better provide a magnetic field for the gap, the magnetic source 40 and the tooth end of the gear 20 are respectively located at two sides of the sensing electrode 30, that is, the magnetic source 40 is also located in the sensing electrode mounting hole, and the connection line between the sensing electrode 30 and the tooth end of the gear 20 is parallel to the magnetic field line, so that the non-magnetic conductive particles are distributed along the magnetic field line to connect the sensing electrode 30 and the tooth end of the gear 20.
The casing 10 is provided with a plurality of output terminals 60, and the output terminals 60 are connected with the sensing electrode 30 and are used for outputting current signals of the sensing electrode 30. In the preferred embodiment of the present invention, an output 60 is used.
In a preferred embodiment of the present invention, the non-magnetic conductive particles are one or more of nano-scale copper powder, nano-scale aluminum powder, nano-scale silver powder, nano-scale copper wire, nano-scale aluminum wire, nano-scale silver wire, and fullerene. Specifically, of course, the nonmagnetic conductive particles are not limited to the above materials, and nonmagnetic in the nonmagnetic conductive particles means nonmagnetic with respect to substances containing iron, cobalt, nickel, and the like.
In a preferred embodiment of the invention, the gap has a width delta of 10-10000 μm as shown in fig. 3. Preferably, the gap has a width delta of 50-2000 μm. Specifically, the width δ of the gap needs to be set according to the rotation speed measurement requirement, since the length of the chain structure formed by connecting the non-magnetic conductive particles is related to time, the length of the chain structure increases with the lapse of time, and of course, the chain structure also breaks, the connection and breaking of the chain structure is a reversible process, and after a certain time, the connection and breaking of the chain structure reach equilibrium. Thus, during the time that the toothed end of the gear 20 is opposite the sensing electrode 30, the chain-like structure needs to be connected to a length sufficient to exceed the width δ of the gap to connect the sensing electrode 30 and the toothed end of the gear 20. Of course, the higher the rotational speed that needs to be measured, the smaller the gap width δ; the width delta of the gap may be increased as the rotational speed to be measured is lower. Of course, it is also necessary to determine the width δ of the gap according to the sensing time, and when the sensing speed is required, the smaller the width δ of the gap is, and when the sensing speed is not required, the width δ of the gap can be increased.
In a preferred embodiment of the invention, the magnetic field has a strength of greater than 0.1 tesla. Specifically, the magnetic field strength of the permanent magnet should be greater than 0.2T (tesla) for water-based magnetic fluids and greater than 0.1T (tesla) for oil-based magnetic fluids. The strength of the magnetic field can control the length of the chain-shaped structure, and the stronger the magnetic field is, the longer the chain-shaped structure is; the weaker the magnetic field, the shorter the length of the chain structure. The strength of the magnetic field can be set according to the rotational speed measurement requirement.
In a preferred embodiment of the present invention, referring to fig. 1-4, in order to ensure that the amount of magnetic fluid is sufficient for testing, a magnetic fluid level probe 50 for detecting the magnetic fluid level is provided on the housing 10. Specifically, a probe mounting hole 14 may be provided on the housing 10, and a magnetic fluid level probe 50 is provided in the probe mounting hole 14. One end of the magnetic fluid level probe 50 extends into the cavity and the other end protrudes out of the housing 10. When the magnetic fluid is insufficient, the magnetic fluid level probe 50 is detached, and the magnetic fluid is supplemented through the probe mounting hole 14.
The setting position of the probe mounting hole 14 can be adjusted according to the requirement, in the preferred embodiment of the invention, the gear 20 rotates in the vertical plane, the sensing electrode 30 is arranged at the top of the inner wall of the shell 10, the probe mounting hole 14 is arranged on the upper surface of the shell 10, as long as the magnetic fluid is insufficient, air can appear at the top of the cavity, and when the magnetic fluid is lower than a certain height, the magnetic fluid is detected by the magnetic fluid level probe 50.
In a preferred embodiment of the present invention, referring to fig. 2 and 5, the gear 20 is a conical gear. In particular, the gear 20 may employ a cylindrical gear or a conical gear. The radial component of the cylindrical gear is too large, preferably a conical gear is used, which is suitable for measuring the gear 20 with a higher rotational speed.
In a preferred embodiment of the present invention, referring to fig. 2, 5 and 6, one end of the gear 20 is rotatably connected to the inner wall of the housing 10 through a bearing 70, the other end of the gear 20 is provided with a gear post 21, the housing 10 is provided with a post hole 16, and the gear post 21 passes through the post hole 16 to outside the cavity. Specifically, when a conical gear is used, the small end of the conical gear is rotatably connected to the inner wall of the housing 10 via the bearing 70, and the large end is connected to the gear post 21. The bearing 70 prevents the gear 20 from slipping in the axial direction and prevents friction from being generated by the contact of the gear 20 with the housing 10.
In a preferred embodiment of the present invention, the gear 20 may also be sleeved on the gear post 21, one end of the gear post 21 is rotatably connected with the inner wall of the housing 10 through the bearing 70, the other end passes through the post hole 16 to the outside of the cavity, and the position of the gear 20 on the gear post 21 can be adjusted to change the width δ of the gap.
The housing 10 includes: a base 11 and a cover 12 connected to the base 11; the base 11 is provided with a flange 13, and the flange 13 is provided with screw holes, and the screw holes can be used for allowing screws to pass through and fix the sensor. The post hole 16 is provided on the cover 12.
In a preferred embodiment of the present invention, neither the gear 20 nor the gear post 21 is magnetic and electrically conductive. Specifically, the gear 20 or the gear post 21 is made of a non-magnetic conductive material, or is coated with a conductive coating on the non-magnetic non-conductive material. The gear teeth may be manufactured by casting, gear shaping, welding, etc. The gear column 21 is adopted as an input end, when the gear column 21 drives the gear 20 to rotate, the gear 20 and the induction electrode 30 are switched on and off, and the rotating speed of the gear 20 is calculated according to the times of switching on and off. The toothed end of the gear 20 is planar for connection with the sensing electrode 30 via non-magnetic conductive particles.
In a preferred embodiment of the present invention, referring to fig. 1, 2 and 6, in order to avoid leakage of magnetic fluid, a sealing magnet 80 is disposed on the inner wall of the housing 10, and the sealing magnet 80 surrounds the gear post 21, that is, the sealing magnet 80 is disposed at the edge of the post hole 16. Further, the inner wall of the housing 10 is provided with a groove 15, specifically, the groove 15 is provided on the cover 12; the sealing magnet 80 is located in the groove 15, and the distance between the sealing magnet 80 and the opening of the groove 15 is 0.02 to 0.2mm. The seal magnet 80 uses rheological properties of the magnetic fluid to form a sealing film having solid phase property at the sealing place so as to isolate the external environment and prevent the internal leakage of the sensor. The sealing magnet adopts a permanent magnet, and the common permanent magnet is a neodymium iron boron permanent magnet and a ferrite permanent magnet.
The invention has the following advantages: (1) The gear type magnetic fluid rotating speed sensor has a simple and compact structure, and each part is relatively independent, so that the gear type magnetic fluid rotating speed sensor is convenient to maintain and overhaul; (2) The gear type magnetic fluid rotating speed sensor has good interchangeability, and can realize modularization, serialization and rapid manufacturing; (3) The gear type magnetic fluid rotating speed sensor has no special requirements on the working environment, and can adapt to various special environments; (4) The invention can adapt to the rotation speed measurement under the high-speed rotation condition by utilizing the self characteristics of the magnetic fluid. (5) The sensor has no special requirement on the length dimension of a sensing area, can be made small, and can be provided with a gap smaller than 50 mu m under the condition of technical permission.
The invention also provides a manufacturing method of the gear type magnetic fluid rotating speed sensor based on any one of the above, which comprises the following steps:
and S100, preparing magnetic fluid according to the nonmagnetic conductive particles.
Specifically, magnetic fluid of different base carrier liquids is selected for suspension dissolution according to the physicochemical properties of non-magnetic micro-conductive particles, and as the temperature-sensitive insulating magnetic fluid has good heat dissipation, the temperature-sensitive insulating magnetic fluid is commonly used, the common temperature-sensitive insulating magnetic fluid is magnetic fluid such as water base, oil base, ester base, fluoroether oil and the like, the base carrier liquid can be prepared by using solvents such as water, engine oil, hydroxyl oil and the like, experimental measurement is required after the preparation, and the self-assembly efficiency of self-assembly into the chain length L under the design magnetic field strength is required to reach 80%.
The magnetic fluid with different magnetization intensity is selected by comprehensively considering the viscosity, pressure and economy of experimental fluid during the selection, the higher the magnetization intensity is, the more obvious the magnetic fluid solid characteristic is, the self-assembly efficiency is greatly improved, meanwhile, the resistance caused by the magnetic viscosity is also greatly increased, and the factors of the resistance caused by the magnetic viscosity and the self-assembly efficiency are required to be comprehensively considered during the manufacturing.
Step S200, setting the position of the sensing electrode 30, the number of teeth of the gear 20, the width delta of the gap, and the intensity of the magnetic field according to the rotation speed of the gear 20.
Specifically, S200 includes the steps of:
step S210, the number of teeth of the sensing electrode 30 and the gear 20 is manufactured according to the condition of the speed measurement input end (such as whether the speed measurement input end has magnetism or not, how the shaft diameter is) and the rotation speed measurement requirement.
In particular, the teeth of the gear 20 should be of symmetrical design, and may be shaped such that involute, rectangular, trapezoidal, etc., asymmetrical designs, or incomplete tooth designs may be used in particular situations.
Step S220, manufacturing the size of the cavity according to the self-assembly experiment in S100, manufacturing the module of the gear 20, the width δ of the gap and the strength of the magnetic field according to the installation position and the rotation speed measurement requirement of the induction electrode 30, further determining the diameter of the gear 20, and selecting the model of the bearing 70, thereby determining the size of the housing 10 according to the width δ of the gap.
The width δ of the gap should be determined by the self-assembly experiment in step S100, and the rotation factor should be considered, so the width δ of the gap should be slightly smaller than the length L of the self-assembled chain structure measured by the experiment, and the value range is L/4< δ < L.
Step S230, manufacturing the magnetic fluid level probe 50 according to the installation position of the sensing electrode 30 and the width δ of the gap.
The magnetic fluid level probe 50 needs to be made of non-magnetic non-conductive materials, the bottom of the magnetic fluid level probe should be lower than the sensing electrode 30, the standard scale should be higher than the tooth end of the gear 20, and the sensor should be kept stand for a period of time when detecting the magnetic fluid level position so as to prevent the magnetic fluid splashed by rotation from affecting the detection of the level position.
Step S240, manufacturing the housing 10 according to the installation environment and the position size, wherein the housing 10 includes: the sensor comprises a base 11 and a cover 12 connected with the base 11, wherein an induction electrode 30, a magnetic source 40, a bearing 70, a gear 20 and a magnetic fluid level probe 50 are sequentially arranged on the sensor base 11, and whether mutual interference exists or not is checked.
Step S250, manufacturing a cover body 12 according to the size of the sensor base 11, manufacturing a groove 15 on the cover body 12 for installing a permanent magnet, filling the prepared magnetic fluid mixed with the non-magnetic conductive particles into a speed measuring cavity through a mounting hole of the magnetic fluid level probe 50, and testing the leakage-proof property of the magnetic fluid.
A gap of 0.02 to 0.2mm is required between the permanent magnet and the opening of the recess 15.
Step S260, after the primary assembly, a power-on test experiment is needed, and the effectiveness of the assembly is ensured.
In summary, the present invention provides a gear type magnetic fluid rotation speed sensor and a manufacturing method thereof, wherein the gear type magnetic fluid rotation speed sensor comprises: the device comprises a shell, a gear, a plurality of induction electrodes and a plurality of magnetic sources; the shell is provided with a cavity, and the gear is arranged in the cavity and can rotate in the cavity; the induction electrode is arranged on the inner wall of the shell, a gap is formed between the induction electrode and the tooth end of the gear, and the magnetic source is arranged on the inner wall of the shell and used for providing a magnetic field at the gap; the cavity is filled with magnetic fluid, the magnetic fluid comprises a plurality of non-magnetic conductive particles, and the non-magnetic conductive particles are used for self-assembling in the magnetic field to connect the induction electrode and the tooth end of the gear. The gear type magnetic fluid rotating speed sensor has a simple and compact structure, and each part is relatively independent, so that the gear type magnetic fluid rotating speed sensor is convenient to maintain and overhaul. And the magnetic fluid self-characteristics are utilized, so that the magnetic fluid can adapt to the rotation speed measurement under the high-speed rotation condition.
It is to be understood that the invention is not limited in its application to the examples described above, but is capable of modification and variation in light of the above teachings by those skilled in the art, and that all such modifications and variations are intended to be included within the scope of the appended claims.
Claims (10)
1. A gear type magnetic fluid rotation speed sensor, characterized in that it comprises: the device comprises a shell, a gear, a plurality of induction electrodes and a plurality of magnetic sources; the shell is provided with a cavity, and the gear is arranged in the cavity and can rotate in the cavity; the induction electrode is arranged on the inner wall of the shell, a gap is formed between the induction electrode and the tooth end of the gear, and the magnetic source is arranged on the inner wall of the shell and used for providing a magnetic field at the gap; the cavity is filled with magnetic fluid.
2. A gear-type magnetic fluid rotation speed sensor according to claim 1 wherein the magnetic fluid comprises a plurality of non-magnetic conductive particles for self-assembling in the magnetic field to connect the sensing electrode and the tooth end of the gear, the gap having a width of 10-10000 μm.
3. The gear-type magnetic fluid rotation speed sensor according to claim 2, wherein the non-magnetic conductive particles are one or more of nano-scale copper powder, nano-scale aluminum powder, nano-scale silver powder, nano-scale copper wire, nano-scale aluminum wire, nano-scale silver wire and fullerene.
4. A gear-type magnetic fluid rotational speed sensor according to claim 1 wherein the strength of the magnetic field is greater than 0.1 tesla.
5. A gear type magnetic fluid rotation speed sensor according to claim 1, wherein a magnetic fluid level probe for detecting the magnetic fluid level is provided on the housing.
6. A gear-type magnetic fluid rotation speed sensor according to claim 1 wherein the gear is a conical gear.
7. A gear type magnetic fluid rotating speed sensor according to claim 1, wherein one end of the gear is rotatably connected with the inner wall of the housing through a bearing, a gear column is arranged at the other end of the gear, a column hole is arranged on the housing, and the gear column passes through the column hole to the outside of the cavity.
8. A gear-type magnetic fluid rotation speed sensor according to claim 7 wherein a seal magnet is provided on the inner wall of the housing, the seal magnet surrounding the gear post.
9. A gear-type magnetic fluid rotation speed sensor according to claim 7 wherein neither the gear nor the gear post is magnetic and electrically conductive.
10. A method for manufacturing a gear type magnetic fluid rotation speed sensor according to any one of claims 1 to 9, comprising the steps of:
preparing magnetic fluid according to the non-magnetic conductive particles;
the position of the induction electrode, the number of teeth of the gear, the width of the gap and the intensity of the magnetic field are set according to the rotating speed of the gear.
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| CN201910452822.6A CN110244075B (en) | 2019-05-28 | 2019-05-28 | Gear type magnetic fluid rotating speed sensor and manufacturing method thereof |
| PCT/CN2020/082862 WO2020238405A1 (en) | 2019-05-28 | 2020-04-02 | Gear-type magnetic fluid-based rotational speed sensor and manufacturing method thereof |
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| CN201910452822.6A CN110244075B (en) | 2019-05-28 | 2019-05-28 | Gear type magnetic fluid rotating speed sensor and manufacturing method thereof |
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| CN110244075B (en) * | 2019-05-28 | 2023-08-29 | 南方科技大学 | Gear type magnetic fluid rotating speed sensor and manufacturing method thereof |
| CN114646774B (en) * | 2021-04-02 | 2024-02-13 | 无锡未科精密技术有限公司 | Portable rotation tester |
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| WO2020238405A1 (en) | 2020-12-03 |
| CN110244075A (en) | 2019-09-17 |
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