CN101246184B - Quasi-two-dimension magnetic fluid acceleration transducer - Google Patents
Quasi-two-dimension magnetic fluid acceleration transducer Download PDFInfo
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- CN101246184B CN101246184B CN2007100639922A CN200710063992A CN101246184B CN 101246184 B CN101246184 B CN 101246184B CN 2007100639922 A CN2007100639922 A CN 2007100639922A CN 200710063992 A CN200710063992 A CN 200710063992A CN 101246184 B CN101246184 B CN 101246184B
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Abstract
The invention provides a quasi two dimensional magnetism fluid accelerometer including non-magnetic cavity, mass block, test device and magnetic fluid, the non-magnetic cavity is a closed container formed by non-magnetic material; test device is equipped in the middle part of the non-magnetic cavity, the mass block double end faces are inclined at a certain angle with normal of interface of non-magnetic cavity and axes of mass block; the test device is equipped between interface, and keeps set preload pressure between the mass block, test device and non-magnetic cavity; and the cavity which is formed between the non-magnetic cavity and mass block is full of magnetic fluid; the test device is used for testing pressure changes between the mass block and the non-magnetic cavity, and outputs acceleration test result signal. The invention has merits of large measure range, controllable measure range, high sensitivity, high reliability, intelligence, long service life and so on.
Description
Technical Field
The invention relates to the field of production and application of acceleration sensors, in particular to a quasi-two-dimensional acceleration sensor based on magnetic fluid.
Background
At present, acceleration sensors are commonly used in various technical fields, such as automobile motion control, building machinery motion control, mechanical vibration detection, aerospace, home appliance product performance detection and the like.
The existing acceleration sensor generally has the following structure.
An acceleration sensor is of a cantilever beam structure, comprises a cantilever beam with a fixed end arranged on a substrate to make reciprocating elastic deformation movement, and the magnitude of external acceleration is determined by detecting the position of the cantilever beam. The common detection mode is that a cantilever beam with one fixed end and the other free end is arranged, a strain gauge is pasted at the root of the cantilever beam, and the displacement value of the root of the cantilever beam is detected through the strain gauge, so that the external input acceleration is determined.
The other acceleration sensor is that the piezoelectric element is arranged at the bottom of the sensor, a mass block is arranged above the piezoelectric element, the mass block is in close contact with the piezoelectric element in the normal direction, the normal line of the contact surface is parallel to the direction of the measured acceleration, the mass block generates a certain displacement when in work, so that the piezoelectric element in contact with the mass block generates an output signal, and the corresponding input acceleration can be detected by detecting the output signal.
The above-mentioned acceleration sensor can only detect the input acceleration in the same direction once installed, but cannot detect the acceleration in other directions, that is, the detection direction has one dimension, and the material inside the acceleration sensor cannot be changed once manufactured, which are disadvantages thereof.
Disclosure of Invention
In view of the problems in the prior art, the present invention aims to provide a quasi-two-dimensional magnetic fluid acceleration sensor, which is an oblique contact piezoelectric acceleration sensor based on magnetic fluid and has the characteristics of two-dimensional detection direction, wide range, controllable measuring range, high sensitivity, high reliability, intelligence, long service life, etc.
The purpose of the invention is realized by the following technical scheme:
a quasi-two-dimensional magnetic fluid acceleration sensor, comprising: non-magnetic cavity, quality piece, detection device and magnetic fluid, wherein:
a non-magnetic cavity: a closed container made of a nonmagnetic material;
a mass block: the two end faces of the mass block and the normal direction of the contact surface of the nonmagnetic cavity form a certain inclination angle with the axis of the mass block; a detection device is arranged among the contact surfaces, and a set pre-tightening pressure is kept among the mass block, the detection device and the nonmagnetic cavity; a cavity formed by the nonmagnetic cavity and the mass block is filled with magnetic fluid;
the detection device comprises: the device is used for detecting the pressure change between the mass block and the nonmagnetic cavity and outputting an acceleration detection result signal.
The quasi-two-dimensional magnetic fluid acceleration sensor further comprises a magnetic field control device, wherein the magnetic field control device is used for changing the viscosity of the magnetic fluid and controlling the axial displacement of the mass block, and the quasi-two-dimensional magnetic fluid acceleration sensor specifically comprises:
excitation coil: the magnetic fluid is wound outside the non-magnetic cavity, a uniform magnetic field is generated by input current, the viscosity of the magnetic fluid is changed, and the axial displacement of the mass block is controlled.
The quasi-two-dimensional magnetic fluid acceleration sensor further comprises a detection control device, and the detection control device is used for controlling the input current of the excitation coil according to an acceleration detection result signal output by the detection device, so that the internal magnetic field of the excitation coil is controlled.
The detection device comprises a piezoelectric element consisting of one or more piezoelectric sheets in a serial connection mode or a parallel connection mode, wherein the piezoelectric element is arranged between the mass block and the nonmagnetic cavity and is used for detecting the displacement change of the mass block and outputting a signal which can be detected by a subsequent detection circuit.
The contact surface of one end of the mass block and the nonmagnetic cavity comprises two contact surfaces forming a certain angle, and a piezoelectric element is arranged between each contact surface.
The end face of the mass block is an outer positioning pyramid surface, the nonmagnetic cavity is provided with an inner pyramid groove, and the outer positioning pyramid surface of the mass block is arranged in the inner pyramid groove of the nonmagnetic cavity to realize circumferential positioning.
The mass block is made of a high specific gravity material, is a cylinder or a prism, and is circumferentially provided with a plurality of grooves or blades for increasing the effective contact area with the magnetic fluid.
The non-magnetic cavity comprises a non-magnetic inner cylinder and a non-magnetic gland, wherein:
the two ends of the nonmagnetic inner cylinder are provided with openings, the two ends of the nonmagnetic inner cylinder are respectively and fixedly provided with a nonmagnetic gland to compress the mass block through screws to form a nonmagnetic cavity, and a preset pre-tightening pressure is generated among the mass block, the detection device and the nonmagnetic cavity; or,
one end of the nonmagnetic inner cylinder is provided with an opening, a nonmagnetic gland is arranged at the opening to compress the mass block to form a nonmagnetic cavity, and preset pre-tightening pressure is generated among the mass block, the detection device and the nonmagnetic cavity; or,
and a non-magnetic sealing ring is also arranged between the non-magnetic inner cylinder and the non-magnetic gland.
The non-magnetic cavity is a cylinder or a prism, and a circumferential groove is formed in the outer wall of the non-magnetic cavity along the axial direction and used for installing the magnet exciting coil.
The magnetic fluid acceleration sensor further comprises an outer shell, the nonmagnetic cavity, the magnetic fluid, the mass block, the detection device or the magnetic field control device are arranged in an inner cavity of the outer shell, the outer shell specifically comprises an outer sleeve, an upper end cover and a lower end cover, the outer sleeve, the upper end cover and the lower end cover are fixed through bolts, and the lower end cover is provided with mounting support legs and/or mounting holes or is provided with mounting holes;
an isolation sleeve is arranged between the outer shell and the nonmagnetic cavity and used for isolating the connection between the magnetic field control device and an external magnetic field and inhibiting the interference of the external magnetic field.
According to the technical scheme provided by the invention, the quasi-two-dimensional magnetic fluid acceleration sensor comprises a nonmagnetic cavity, a mass block, a detection device and a magnetic fluid, wherein the nonmagnetic cavity is a closed container made of nonmagnetic materials; the mass block is arranged in the middle of the nonmagnetic cavity, and the normal direction of the two end surfaces of the mass block and the contact surface of the nonmagnetic cavity and the axis of the mass block form a certain inclination angle; a detection device is arranged among the contact surfaces, and a set pre-tightening pressure is kept among the mass block, the detection device and the nonmagnetic cavity; a cavity formed by the nonmagnetic cavity and the mass block is filled with magnetic fluid; the detection device is used for detecting the pressure change between the mass block and the nonmagnetic cavity and outputting an acceleration detection result signal.
Specifically, a mass block and a plurality of piezoelectric elements can be placed in a nonmagnetic cavity which is made of nonmagnetic materials and filled with magnetic fluid, the mass block and the nonmagnetic cavity are kept coaxial under the circumferential positioning action of a nonmagnetic gland, the piezoelectric elements are adhered to two inclined opposite planes of an inner pyramid groove of the nonmagnetic gland, the contact surface normals of the two piezoelectric elements are intersected at an inclined angle, the contact surface normal of each piezoelectric element and the axis of the mass block form an inclined angle, the nonmagnetic gland plays a role in positioning and also provides a pretightening force, and when the nonmagnetic gland is locked, the generated pretightening force presses the piezoelectric elements and the mass block tightly to enable the piezoelectric elements and the mass block to be in close contact with each other on the contact surface of the piezoelectric elements; when external acceleration exists, the mass block can generate stretching or compressing effect on the piezoelectric element due to the inertia effect, the displacement of the mass block can be determined by detecting the output signal of the piezoelectric element, and then the value of the external acceleration is determined, meanwhile, the mass block is also acted by the damping force of the magnetic fluid, the displacement of the mass block can be controlled by controlling the damping force of the magnetic fluid, and therefore the change of the detection range is realized.
The invention has novel structure, avoids the traditional cantilever beam structure, introduces the piezoelectric element, and leads the mass block to be closely contacted with the piezoelectric element through the pretightening force provided by the non-magnetic gland, thereby enhancing the sensitivity of the acceleration sensor on one hand, effectively increasing the rigidity of the acceleration sensor on the other hand, improving the measuring range of the acceleration sensor and realizing the wide-range detection of the acceleration sensor; two piezoelectric elements are arranged on the inclined opposite planes of the inner pyramid grooves of each non-magnetic gland, and the two ends of the mass block are provided with corresponding pyramid surfaces for realizing the surface contact of the mass block and the piezoelectric elements; the normal lines of the contact surfaces of the two piezoelectric elements are intersected at an inclination angle, meanwhile, the normal line of the contact surface of each piezoelectric element and the axis of the mass block form an inclination angle, when the acceleration sensor bears horizontal acceleration or vertical acceleration, the mass block generates horizontal displacement or vertical displacement due to inertia, and the two displacement can be decomposed into displacement parallel to the contact surface of the piezoelectric element and displacement perpendicular to the contact surface of the piezoelectric element, so that the input horizontal acceleration or the input vertical acceleration has corresponding output quantity on the piezoelectric element, and the acceleration sensor can detect the input acceleration in two-dimensional directions; the mass block is provided with the inclined groove, so that the effective contact area of the mass block and the magnetic fluid is increased, the damping force of the magnetic fluid can be sensed in the horizontal direction or the vertical direction at the same time, and the displacement of the mass block in the horizontal direction or the vertical direction is controlled; when horizontal acceleration is input, the two piezoelectric elements on the same axial side are pressed, the two piezoelectric elements on the other side are released, when vertical acceleration is input, the two piezoelectric elements on the same end face are pressed, and the two piezoelectric elements on the other end face are released; in addition, the invention utilizes the viscosity controllability characteristic of the magnetic fluid, changes the magnetic field intensity applied on the magnetic fluid by changing the current of the magnet exciting coil, and achieves the purpose of controlling the viscosity of the magnetic fluid, thereby achieving the control of the measuring range of the acceleration sensor and realizing the characteristic of large measuring range. The method has the characteristics of two-dimension detection direction, wide range, controllable measuring range, high sensitivity, high reliability, intelligence, long service life and the like.
Drawings
Fig. 1 is a schematic perspective exploded view of a quasi-two-dimensional magnetic fluid acceleration sensor according to the present invention;
FIG. 2 is a schematic structural diagram of a quasi-two-dimensional magnetic fluid acceleration sensor according to the present invention;
fig. 3 is a schematic diagram of a partially enlarged structure of the quasi-two-dimensional magnetic fluid acceleration sensor according to the present invention.
Detailed Description
The quasi-two-dimensional magnetic fluid acceleration sensor comprises a nonmagnetic cavity, a mass block, a detection device and magnetic fluid, wherein the nonmagnetic cavity is a closed container made of nonmagnetic materials; the mass block is arranged in the middle of the nonmagnetic cavity, and the normal direction of the two end surfaces of the mass block and the contact surface of the nonmagnetic cavity and the axis of the mass block form a certain inclination angle; a detection device is arranged among the contact surfaces, and a set pre-tightening pressure is kept among the mass block, the detection device and the nonmagnetic cavity; a cavity formed by the nonmagnetic cavity and the mass block is filled with magnetic fluid; the detection device is used for detecting the pressure change between the mass block and the nonmagnetic cavity and outputting an acceleration detection result signal.
In particular to a mass block and a plurality of piezoelectric elements which are arranged in a nonmagnetic cavity which is made of nonmagnetic materials and is filled with magnetic fluid, the mass block and the nonmagnetic cavity are kept coaxial by the circumferential positioning action of the inner pyramid groove of the nonmagnetic gland, piezoelectric elements are pasted on two inclined opposite planes of an inner pyramid groove of the non-magnetic gland, the contact surface normals of the two piezoelectric elements are intersected at an inclined angle, the contact surface normal of each piezoelectric element and the axis of the mass block form an inclined angle, the non-magnetic gland not only plays a role in circumferential positioning of the mass block and the piezoelectric elements, but also provides necessary pretightening force, when the non-magnetic gland is locked, the generated pretightening force presses the piezoelectric element and the mass block tightly to ensure that the piezoelectric element is tightly contacted with the mass block, the sensor is used for increasing the rigidity of the acceleration sensor and also increasing the measurement sensitivity of acceleration; when external acceleration exists, the mass block generates stretching or compressing effect on the piezoelectric element which is in close contact with the mass block due to the inertia effect: when horizontal acceleration is input, the two piezoelectric elements on the same shaft side are pressed, the two piezoelectric elements on the other side are released, when vertical acceleration is input, the two piezoelectric elements on the same end face are pressed, and the two piezoelectric elements on the other end face are released, so that various interferences can be effectively eliminated by adopting a differential detection mode, the accuracy of detecting the displacement of the mass block is improved, the displacement of the mass block can be determined by detecting an output signal of the piezoelectric elements, and the value of the external two-dimensional acceleration is determined; the magnetic field of the exciting coil can be controlled by controlling the input current of the exciting coil, the viscosity of the magnetic fluid can be changed by the magnetic field of the exciting coil, and the damping force of the magnetic fluid on the mass block can be changed by changing the viscosity of the magnetic fluid, so that the displacement of the mass block can be controlled, the wide-range detection of the acceleration sensor can be realized, and the range of the range can be dynamically controlled.
As shown in fig. 1 and 2, the basic structure of the quasi-two-dimensional acceleration sensor according to the embodiment of the present invention includes: non-magnetic cavity, magnetic fluid 10, proof mass 12 and detection device, wherein:
the nonmagnetic cavity is a closed container made of nonmagnetic materials, the interior of the nonmagnetic cavity is filled with magnetic fluid 10, the nonmagnetic cavity comprises a nonmagnetic inner cylinder 9 and a nonmagnetic gland 3, two ends of the nonmagnetic inner cylinder 9 in the embodiment are open, the nonmagnetic gland 3 is arranged at two ends of the nonmagnetic inner cylinder through a first screw 13, the nonmagnetic cavity is locked to form a closed nonmagnetic cavity, and the interior of the closed nonmagnetic cavity is filled with the magnetic fluid 10; sometimes, when the machining process allows, the non-magnetic inner cylinder 9 may be an opening at one end, a non-magnetic gland is installed at the opening through a first screw 13 to compress the mass 3 to form a non-magnetic cavity, and the inside of the non-magnetic cavity is filled with the magnetic fluid 10. Meanwhile, in order to better realize the sealing of the nonmagnetic cavity (mainly the sealing of the magnetic fluid), a nonmagnetic sealing ring 5 can be arranged between the nonmagnetic inner cylinder 9 and the nonmagnetic gland 3 to prevent the magnetic fluid 10 from leaking.
The outer wall of the non-magnetic cavity in this example is provided with a circumferential groove along the axial direction, that is, the outer wall of the non-magnetic inner cylinder 9 is provided with a circumferential groove along the axial direction for installing the excitation coil 8, and two end surfaces of the non-magnetic inner cylinder 9 are provided with wall thicknesses along the axial direction for fixing the non-magnetic gland 3.
The nonmagnetic cavity in this example is cylindrical, that is, the shape of the nonmagnetic inner cylinder 9 is cylindrical, a through hole is formed in the nonmagnetic inner cylinder, the mounting wall thickness is reserved on two end faces, and a circumferential groove is formed in the outer wall of the nonmagnetic inner cylinder 9 along the axial direction and used for mounting the excitation coil 8; certainly, the nonmagnetic cavity may also be a prism, that is, the shape of the nonmagnetic inner cylinder 9 is a prism, a through hole is formed inside the nonmagnetic cavity, the wall thickness is reserved at two end faces, a circumferential groove is formed in the outer wall of the nonmagnetic inner cylinder 9 along the axial direction, the groove is used for arranging a coil fixing sleeve, and the excitation coil 8 can be wound on the coil fixing sleeve.
The magnetic fluid 10 is any one of or a combination of any several of magnetic fluids such as magnetic fluid, magnetic composite fluid, or magnetic rheological fluid. The nonmagnetic inner cylinder 9 of the acceleration sensor is filled with magnetic fluid 10, and the mass block 12 is arranged in the magnetic fluid 10 and is acted by the damping force of the magnetic fluid 10. By changing the viscosity of the magnetic fluid 10, the damping force of the magnetic fluid 10 on the mass block 12 can be changed, so that the displacement of the mass block 12 in the vertical direction or the horizontal direction can be changed.
The detection device comprises a piezoelectric element 4 formed by one or more piezoelectric sheets in a serial connection mode or a parallel connection mode, wherein the piezoelectric element 4 is arranged between the mass block 12 and the nonmagnetic cavity and is used for detecting the displacement change of the mass block 12 and outputting a signal which can be detected by a subsequent detection circuit.
The contact surface of one end of the mass block 12 and the nonmagnetic cavity comprises two contact surfaces forming a certain angle, and a piezoelectric element 4 is arranged between each contact surface. In practice, the end face of the mass block 12 is an outer positioning pyramid surface, the nonmagnetic cavity is provided with an inner pyramid groove, and the outer positioning pyramid surface of the mass block 12 is arranged in the inner pyramid groove of the nonmagnetic cavity to realize circumferential positioning. The method specifically comprises the following steps:
the piezoelectric element 4 is made of a material having a piezoelectric effect, such as a quartz crystal, a piezoelectric ceramic, a piezoelectric thin film, or another novel piezoelectric material. The piezoelectric element 4 in this example is a rectangular parallelepiped thin plate adhered to two surfaces of the inner pyramid groove of the non-magnetic gland 3, which are opposite to each other in inclination; of course, other alternative shapes of the piezoelectric element 4, such as a prism, a cylinder, etc., are not excluded. When the non-magnetic gland 3 is locked, the piezoelectric element 4 is acted by a pre-tightening force to be in close contact with the mass block 12 on the contact surface, and the piezoelectric element 4 can normally sense the displacement of the mass block 12.
The mass 12 is made of a high specific gravity material, generally requiring a specific gravity of 14-19 g/cc, and may be made of a metal such as a high specific gravity alloy, e.g., tungsten alloy, copper-tungsten alloy, etc. The mass block may also be non-metallic, as long as the above-mentioned specific gravity range is met. Two end surfaces of the mass block 12 are provided with positioning conical surfaces, and the positioning conical surfaces are positioned through the surfaces of inner pyramid grooves of the non-magnetic gland 3, in the embodiment, the mass block 12 is a cuboid, inclined grooves are formed in the circumference of the cuboid, and the inclined grooves can be spiral and used for increasing the effective contact area of the mass block 12 and the magnetic fluid 10 and sensing the damping force of the magnetic fluid in the horizontal direction or the vertical direction; of course, the mass 12 may be a cylinder, and the same function may be achieved by providing conical surfaces at both end surfaces and providing inclined grooves in the circumferential direction of the cylinder. When the non-magnetic gland 3 is locked, the mass block 12 is tightly contacted with the piezoelectric element 4 by the generated pretightening force, so that the sensitivity of the acceleration sensor can be increased, and meanwhile, the rigidity of the acceleration sensor can be increased due to the material characteristics of the piezoelectric element 4; when external acceleration exists, the mass block 12 outputs corresponding displacement due to the self-inertia effect, and the displacement of the mass block 12 becomes the input of the piezoelectric element 4 because the piezoelectric element 4 is in close contact with the mass block 12; because the inclined groove is arranged on the circumference of the mass block 12, the damping force of the magnetic fluid can be sensed in the horizontal direction or the vertical direction at the same time, when the viscosity of the magnetic fluid 10 is changed, the damping force of the mass block 12, which is subjected to the magnetic fluid 10, is changed, so that the output displacement of the mass block is also changed: when the same acceleration is input, if the viscosity of the magnetic fluid 10 is increased, the damping force of the mass block 12 exerted by the magnetic fluid 10 is relatively increased, the output displacement of the mass block 12 is relatively reduced, and at this time, the acceleration sensor is suitable for measuring the input acceleration with a larger numerical value; if the viscosity of the magnetic fluid 10 is reduced, the damping force of the mass 12 exerted by the magnetic fluid 10 is relatively reduced, the output displacement of the mass 12 is relatively increased, and the acceleration sensor is suitable for measuring the input acceleration with a relatively small value. Therefore, by controlling the viscosity of the magnetic fluid 10, the range of the acceleration sensor can be controlled, and at the same time, by greatly increasing the viscosity of the magnetic fluid 10, the acceleration sensor can achieve a large range of measurement.
The circumferential arrangement of the mass 12 in this example with oblique recesses can also be replaced by annular blades, which also meets the above-mentioned requirements.
In order to better complete the measurement, the acceleration sensor further comprises a magnetic field control device for changing the viscosity of the magnetic fluid and controlling the axial displacement of the mass. The excitation coil 8 is arranged between the nonmagnetic inner cylinder 9 and the nonmagnetic sleeve 7, and the coil is wound on the groove of the nonmagnetic inner cylinder 9 and keeps coaxial with the nonmagnetic inner cylinder 9; or a coaxial coil can be fixedly sleeved on the non-magnetic inner cylinder 9, and the excitation coil 8 is wound in the coil fixing sleeve. The excitation coil 8 is used for generating a uniform magnetic field inside the nonmagnetic inner cylinder 9, and the energizing current of the excitation coil 8 is changed to change the magnetic field inside the nonmagnetic inner cylinder 9: increasing the energizing current of the exciting coil 8 will increase the magnetic field inside the non-magnetic inner cylinder 9; reducing the energization current of the exciting coil 8 reduces the magnetic field inside the nonmagnetic inner tube 9. The non-magnetic sleeve 7, the non-magnetic washer 2 and the non-magnetic gland 3 are used for isolating the relation between the magnetic field generated by the excitation coil 8 and the external magnetic field and preventing the interference of the external magnetic field.
The acceleration sensor further comprises a shell, the nonmagnetic cavity, the magnetic fluid 10, the mass block 12, the detection device or the magnetic field control device are arranged in an inner cavity of the shell, the shell specifically comprises an outer sleeve 6, an upper end cover 11 and a lower end cover 1, the outer sleeve 6, the upper end cover 11 and the lower end cover 1 are fixed through a second screw 14, and the lower end cover 1 is provided with mounting support legs 15 and/or mounting holes 16.
An isolation sleeve is arranged between the outer shell and the nonmagnetic cavity and used for isolating the connection between the magnetic field control device and an external magnetic field and inhibiting the interference of the external magnetic field. The spacer comprises a non-magnetic sleeve 7 and a non-magnetic washer 2.
The acceleration sensor further comprises a detection control device for controlling the input current of the exciting coil according to the acceleration detection result signal output by the detection device, thereby controlling the internal magnetic field of the exciting coil.
The working principle of the acceleration sensor is as follows:
as shown in fig. 1, 2 and 3, a non-magnetic inner cylinder 9 is filled with a magnetic fluid 10, in the magnetic fluid 10, a mass block 12 and a piezoelectric element 4 are positioned by an inner pyramid groove of a non-magnetic gland 3, when the non-magnetic gland 3 is locked, the generated pretightening force causes the mass block 12 and the piezoelectric element 4 to be in close contact, the mass block 12 is also subjected to the damping force of the magnetic fluid 10, the mass block 12 is provided with an inclined groove to increase the effective contact area with the magnetic fluid 10, so that the damping force of the magnetic fluid can be sensed in the horizontal direction or the vertical direction at the same time, and the non-magnetic gland 3 is provided with a sealing ring 5, so that the magnetic fluid 10 cannot overflow; the outer wall of the non-magnetic inner cylinder 9 is provided with a circumferential groove along the axial direction, the excitation coil 8 is arranged in the circumferential groove and used for providing an even magnetic field, the non-magnetic sleeve 9 is arranged outside the excitation coil 8, and the non-magnetic gland 3 is provided with a non-magnetic gasket and used for isolating the relation between the magnetic field of the excitation coil 8 and an external magnetic field and preventing the interference of an external magnetic field.
When external acceleration exists, the mass block 12 outputs corresponding displacement amount due to the action of self inertia, and the displacement amount of the mass block 12 becomes the input amount of the piezoelectric element 4 because the piezoelectric element 4 is in close contact with the mass block 12: when vertical acceleration is input, the mass block 12 generates displacement in the vertical direction due to inertia, at this time, two piezoelectric elements 4 located on the same end face are compressed, the piezoelectric element 4 located on the other end face is released, the displacement generated by the mass block 12 in the vertical direction is decomposed into a component perpendicular to the contact face of the piezoelectric elements 4 and a component parallel to the contact face of the piezoelectric elements 4, at this time, the signs of output signals of the two piezoelectric elements 4 located on the same end face are the same, and the signs of output signals of the piezoelectric elements located on different end faces are opposite, so that the value of the vertical acceleration can be determined by detecting the output quantity of the piezoelectric elements 4; when horizontal acceleration is input, the mass block 12 generates displacement in the horizontal direction due to inertia, at this time, the two piezoelectric elements 4 on the same axial side are compressed, the two piezoelectric elements 4 on the other axial side are released, the displacement generated in the horizontal direction of the mass block 12 is decomposed into a component perpendicular to the contact surface of the piezoelectric elements 4 and a component parallel to the contact surface of the piezoelectric elements 4, at this time, the output signals of the two piezoelectric elements 4 on the same axial side have the same sign, and the output signals of the piezoelectric elements on different axial sides have opposite signs. The magnitude of the output signal of the piezoelectric element 4 can determine the value of the input acceleration, and the comparison of the signs of the output signals of different piezoelectric elements can determine whether the input acceleration is vertical acceleration or horizontal acceleration, so that the two-dimension of the detection direction is realized.
The viscosity of the magnetic fluid 10 can be changed by controlling the energizing current of the exciting coil 8 and changing the magnitude of the generated magnetic field, and the damping force acting on the mass block 12 can be changed because the mass block 12 is subjected to the damping force action of the magnetic fluid 10, so that the output displacement of the mass block 12 can be changed. When the same external acceleration is input, the energizing current of the exciting coil 8 is changed, the viscosity of the magnetic fluid 10 is changed, and the displacement of the mass block 12 can be changed, so that the measuring range controllability of the acceleration sensor can be realized, and meanwhile, as the inclined grooves are arranged in the circumferential direction of the mass block 12, the damping force of the magnetic fluid can be sensed in the horizontal direction or the vertical direction at the same time, so that the measuring range controllability of the acceleration sensor in the two-dimensional direction can be realized; if the viscosity of the magnetic fluid 10 is greatly increased, the displacement of the mass 12 is reduced when the same external acceleration is input. Thus, a large range of acceleration measurements can be achieved.
If the output of the piezoelectric element 4 is further fed back to the control circuit of the exciting coil 8, the control circuit can automatically adjust the energizing current of the exciting coil 8 according to the output of the piezoelectric element 4, and thus the intelligence of the acceleration sensor can be realized.
The acceleration sensor structure does not adopt the traditional cantilever beam working mode any more, but introduces the piezoelectric element as the elastic element, so that the measurement sensitivity of the acceleration sensor is improved, the elastic element does not have physical deformation such as bending, torsion and the like in the working process, and the service life and the reliability of the acceleration sensor are also improved.
Therefore, the invention has the following advantages and beneficial effects:
1. the invention has novel structure, avoids the traditional cantilever beam structure, changes the working principle of the mass block and is an innovation on the principle of the existing acceleration sensor;
2. the invention adopts the structure of oblique contact between the mass block and the piezoelectric element, changes the working principle that the axis of the mass block is parallel to the normal of the contact surface of the piezoelectric element in the traditional one-dimensional piezoelectric acceleration sensor, and achieves the purpose of detecting the input acceleration in the two-dimensional direction, thereby realizing the two-dimensional property of the detection direction;
3. the invention adopts the viscosity controllability characteristic of the magnetic fluid, changes the magnetic field intensity applied on the magnetic fluid by controlling the electrifying current of the magnet exciting coil, and achieves the purpose of controlling the viscosity of the magnetic fluid, thereby realizing the range controllability of the acceleration sensor;
4. the invention introduces the multi-groove mass block and the piezoelectric element, and can realize the detection of wide-range input acceleration by improving the viscosity of the magnetic fluid;
5. the differential connection of the output signals of the piezoelectric elements is adopted, so that various interferences can be effectively eliminated, and the detection accuracy is improved;
6. the invention eliminates the elastic deformation of bending and torsion generated by the elastic element in the motion process, and improves the working reliability of the acceleration sensor;
the above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (12)
1. A quasi-two-dimensional magnetic fluid acceleration sensor, comprising: non-magnetic cavity, quality piece, detection device and magnetic fluid, wherein:
a non-magnetic cavity: a closed container made of a nonmagnetic material;
a mass block: the two end faces of the mass block and the normal direction of the contact surface of the nonmagnetic cavity form a certain inclination angle with the axis of the mass block; a detection device is arranged among the contact surfaces, and a set pre-tightening pressure is kept among the mass block, the detection device and the nonmagnetic cavity; a cavity formed by the nonmagnetic cavity and the mass block is filled with magnetic fluid;
the detection device comprises: the device is used for detecting the pressure change between the mass block and the nonmagnetic cavity and outputting an acceleration detection result signal.
2. The quasi-two-dimensional magnetic fluid acceleration sensor according to claim 1, further comprising a magnetic field control device for changing the viscosity of the magnetic fluid and controlling the displacement of the mass in the axial direction, specifically comprising:
excitation coil: the magnetic fluid is wound outside the non-magnetic cavity, a uniform magnetic field is generated by input current, the viscosity of the magnetic fluid is changed, and the axial displacement of the mass block is controlled.
3. The quasi-two-dimensional magnetic fluid acceleration sensor according to claim 2, further comprising detection control means for controlling an input current of the exciting coil based on an acceleration detection result signal output from the detection means, thereby controlling an internal magnetic field of the exciting coil.
4. The quasi-two-dimensional magnetic fluid acceleration sensor according to claim 1 or 2, characterized in that the detection device comprises a piezoelectric element formed by one or more piezoelectric sheets in series or in parallel, the piezoelectric element is disposed between the mass and the nonmagnetic cavity for detecting the displacement change of the mass and outputting a signal for the subsequent detection circuit to detect.
5. The quasi-two-dimensional magnetic fluid acceleration sensor according to claim 4, characterized in that the contact surface of the one end of the mass with the non-magnetic cavity comprises two contact surfaces at an angle, and a piezoelectric element is disposed between each contact surface.
6. The quasi-two-dimensional magnetic fluid acceleration sensor according to claim 5, characterized in that the end face of the mass block is an outer positioning pyramid, the nonmagnetic cavity is provided with inner pyramid grooves, and the outer positioning pyramid of the mass block is arranged in the inner pyramid grooves of the nonmagnetic cavity to realize circumferential positioning.
7. A quasi-two-dimensional magnetic fluid acceleration sensor according to claim 1 or 2, characterized in that the mass is made of a high specific gravity material, and the mass is a cylinder or a prism, and a plurality of grooves or vanes are provided on the circumference of the mass for increasing the effective contact area with the magnetic fluid.
8. The quasi-two-dimensional magnetic fluid acceleration sensor according to claim 1 or 2, characterized in that the non-magnetic cavity comprises a non-magnetic inner cylinder and a non-magnetic gland, wherein:
the two ends of the nonmagnetic inner cylinder are provided with openings, the two ends of the nonmagnetic inner cylinder are respectively and fixedly provided with a nonmagnetic gland to compress the mass block through screws to form a nonmagnetic cavity, and a preset pre-tightening pressure is generated among the mass block, the detection device and the nonmagnetic cavity; or,
one end of the nonmagnetic inner cylinder is provided with an opening, a nonmagnetic gland is arranged at the opening to compress the mass block to form a nonmagnetic cavity, and preset pre-tightening pressure is generated among the mass block, the detection device and the nonmagnetic cavity.
9. The quasi-two-dimensional magnetic fluid acceleration sensor according to claim 8, characterized in that a non-magnetic sealing ring is further disposed between the non-magnetic inner cylinder and the non-magnetic gland.
10. The quasi-two-dimensional magnetic fluid acceleration sensor according to claim 8, characterized in that the non-magnetic cavity is a cylinder or a prism, and the outer wall is provided with a circumferential groove along the axial direction for mounting the excitation coil.
11. The magnetic fluid acceleration sensor of claim 2, characterized by further comprising an outer housing, wherein the nonmagnetic cavity, the magnetic fluid, the mass block, the detection device or the magnetic field control device are disposed in an inner cavity of the outer housing, the outer housing specifically comprises an outer sleeve, an upper end cap and a lower end cap, the outer sleeve, the upper end cap and the lower end cap are fixed by bolts, and the lower end cap is provided with mounting legs and/or mounting holes.
12. The magnetic fluid acceleration sensor of claim 11, characterized in that an isolation sleeve is disposed between the outer casing and the nonmagnetic cavity for isolating the magnetic field control device from the external magnetic field and suppressing the external magnetic field interference.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2007100639922A CN101246184B (en) | 2007-02-15 | 2007-02-15 | Quasi-two-dimension magnetic fluid acceleration transducer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2007100639922A CN101246184B (en) | 2007-02-15 | 2007-02-15 | Quasi-two-dimension magnetic fluid acceleration transducer |
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| CN101246184B true CN101246184B (en) | 2011-03-23 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103760616B (en) * | 2014-01-24 | 2017-01-04 | 天津大学 | Magnetic fluid compound gravity gradiometer |
| CN105856188B (en) * | 2016-05-06 | 2017-11-07 | 简燕梅 | Portable Flexible Building Structures detect robot |
| CN115236573B (en) * | 2022-09-19 | 2022-11-25 | 河北工业大学 | Magnetic field sensor and device for testing two-dimensional piezoelectric vector magnetic characteristics |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1146558A (en) * | 1994-12-12 | 1997-04-02 | 株式会社村田制作所 | Installation allocation for acceleration measuring elements |
| CN1766647A (en) * | 2004-09-23 | 2006-05-03 | 伊纳拉伯斯技术公司 | Magnetofluidic accelerometer with partial filling of cavity with magnetic fluid |
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- 2007-02-15 CN CN2007100639922A patent/CN101246184B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1146558A (en) * | 1994-12-12 | 1997-04-02 | 株式会社村田制作所 | Installation allocation for acceleration measuring elements |
| CN1766647A (en) * | 2004-09-23 | 2006-05-03 | 伊纳拉伯斯技术公司 | Magnetofluidic accelerometer with partial filling of cavity with magnetic fluid |
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| Title |
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| JP特开2002-148276A 2002.05.22 |
| JP特开2002-40042A 2002.02.06 |
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| 刘桂雄等.基于磁流体独有特性的各种潜在传感器.功能材料37 5.2006,37(5),756-759. |
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