CN101246184B - Quasi-two-dimension magnetic fluid acceleration transducer - Google Patents

Abstract

A quasi-two-dimensional magnetic fluid acceleration sensor according to the present invention includes a non-magnetic cavity, a mass block, a detection device and a magnetic fluid. The non-magnetic cavity is a closed container made of non-magnetic material; In the middle of the cavity, the normal direction between the two ends of the mass block and the contact surface of the non-magnetic cavity forms a certain inclined angle with the axis of the mass block; and a detection device is provided between the contact surfaces, and the mass block, the detection device and the non-magnetic The set pre-tightening pressure is maintained between the cavities; and the cavity formed by the non-magnetic cavity and the mass block is filled with magnetic fluid; the detection device is used to detect the pressure change between the mass block and the non-magnetic cavity, and the output acceleration detection result signal. It has the characteristics of two-dimensional detection direction, large range, range controllability, high sensitivity, intelligence, high reliability, and long working life.

Description

Quasi-two-dimensional magnetic fluid acceleration sensor

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 technique

At present, acceleration sensors are commonly used in many technical fields, such as automobile motion control, construction machinery motion control, mechanical vibration detection, aerospace, home appliance performance detection and so on.

Existing acceleration sensors usually have the following structures.

An acceleration sensor adopts a cantilever beam structure, including a cantilever beam whose fixed end is arranged on a substrate for reciprocating elastic deformation movement, and the external acceleration is determined by detecting the position of the cantilever beam. The commonly used detection method is to set a cantilever beam with one end fixed and the other end free to move, attach a strain gauge to the root of the cantilever beam, and use the strain gauge to detect the displacement value of the cantilever beam root to determine the external input acceleration.

Another type of acceleration sensor is to install the piezoelectric element at the bottom of the sensor, and set a mass block above the piezoelectric element. The mass block is in close contact with the piezoelectric element in the normal direction, and the normal line of the contact surface is parallel to the direction of the measured acceleration. The quality block produces a certain amount of displacement, so that the piezoelectric element in contact with it generates an output signal, and the corresponding input acceleration can be detected by detecting the output signal.

Once the above-mentioned acceleration sensor is installed, it can only detect the input acceleration in the same direction, but cannot detect the acceleration in other directions, that is, its detection direction is one-dimensional, and at the same time, the material inside the acceleration sensor cannot be changed once it is manufactured. , these are their shortcomings.

Contents of the invention

In view of the problems existing in the above-mentioned prior art, the object of the present invention is to provide a quasi-two-dimensional magnetic fluid acceleration sensor, the core of which is an oblique contact piezoelectric acceleration sensor based on magnetic fluid, which has two-dimensionality in the detection direction, large range, and adjustable range. Controllability, high sensitivity, high reliability, intelligence, long working life and so on.

The purpose of the present invention is achieved through the following technical solutions:

A quasi-two-dimensional magnetic fluid acceleration sensor, comprising: a non-magnetic cavity, a mass, a detection device and a magnetic fluid, wherein:

Non-magnetic cavity: a closed container made of non-magnetic materials;

Mass block: located in the middle of the non-magnetic cavity, the normal direction of the contact surface between the two ends of the mass block and the non-magnetic cavity forms a certain inclined angle with the axis of the mass block; and a detection device is installed between the contact surfaces, and the mass The set pre-tightening pressure is maintained between the block, the detection device and the non-magnetic cavity; and the cavity formed by the non-magnetic cavity and the mass block is filled with magnetic fluid;

Detection device: used to detect the pressure change between the mass block and the non-magnetic cavity, and output the acceleration detection result signal.

The quasi-two-dimensional magnetic fluid acceleration sensor also includes a magnetic field control device for changing the viscosity of the magnetic fluid and controlling the axial displacement of the mass block, specifically including:

Excitation coil: wound outside the non-magnetic cavity, a uniform magnetic field is generated by inputting current, the viscosity of the magnetic fluid is changed, and the axial displacement of the mass is controlled.

The quasi-two-dimensional magnetic fluid acceleration sensor further includes a detection control device for controlling the input current of the excitation coil according to the acceleration detection result signal output by the detection device, thereby controlling the internal magnetic field of the excitation coil.

The detection device includes a piezoelectric element composed of one or more piezoelectric sheets connected in series or in parallel, and the piezoelectric element is arranged between the mass block and the non-magnetic cavity to detect the displacement change of the mass block , and output a signal that can be detected by a subsequent detection circuit.

The contact surface between one end of the mass block and the non-magnetic cavity includes two contact surfaces at a certain angle, and piezoelectric elements are arranged between each contact surface.

The end face of the mass block is an outer positioning pyramid surface, the non-magnetic 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 non-magnetic cavity to achieve circumferential positioning.

The mass block is made of high specific gravity material, and the mass block is a cylinder or a prism, and a plurality of grooves or blades are arranged around the mass block to increase the effective contact area with the magnetic fluid .

The non-magnetic cavity includes a non-magnetic inner cylinder and a non-magnetic gland, wherein:

Both ends of the non-magnetic inner cylinder are open, and a non-magnetic gland is fixed at both ends to press the mass block by screws to form a non-magnetic cavity, and a holding force is generated between the mass block, the detection device and the non-magnetic cavity. the set preload pressure; or,

One end of the non-magnetic inner cylinder is open, and a non-magnetic gland is installed at the opening to press the mass block to form a non-magnetic cavity, and a preload is generated between the mass block, the detection device and the non-magnetic cavity to maintain the setting pressure; or,

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 the outer wall is provided with a circumferential groove along the axial direction for installing the excitation coil.

The magnetic fluid acceleration sensor also includes an outer casing, and the non-magnetic cavity, magnetic fluid, mass, detection device or magnetic field control device are arranged in the inner cavity of the outer casing, and the outer casing specifically includes an outer sleeve and an upper end cover and the lower end cover, the outer sleeve and the upper end cover and the lower end cover are fixed by bolts, and the lower end cover is provided with mounting feet and/or mounting holes, or;

An isolation sleeve is provided between the outer shell and the non-magnetic cavity, which is used to isolate the connection between the magnetic field control device and the external magnetic field, and suppress the interference of the external magnetic field.

It can be seen from the technical solution provided by the present invention that the quasi-two-dimensional magnetic fluid acceleration sensor described in the present invention includes a non-magnetic cavity, a mass, a detection device and a magnetic fluid, and the non-magnetic cavity is made of a non-magnetic material The airtight container constituted; the mass block is arranged in the middle of the non-magnetic cavity, and the normal direction of the contact surface between the two ends of the mass block and the non-magnetic cavity forms a certain inclined angle with the axis of the mass block; and a detection device is provided between the contact surfaces , and maintain a set pre-tightening pressure between the mass block, the detection device and the non-magnetic cavity; and the cavity formed by the non-magnetic cavity and the mass block is filled with magnetic fluid; the detection device is used to detect the mass block and the non-magnetic The pressure change between the cavities outputs the acceleration detection result signal.

Specifically, a mass block and multiple piezoelectric elements can be placed inside a non-magnetic cavity filled with magnetic fluid composed of non-magnetic materials, and the mass block and the non-magnetic cavity can be connected through the circumferential positioning of the non-magnetic gland. Keeping the same axis, paste the piezoelectric element on the two inclined opposite planes of the inner pyramid groove of the non-magnetic gland. The contact surface normals of the two piezoelectric elements intersect at an oblique angle, and the contact surface normal of each piezoelectric element The line and the axis of the mass block form an inclined angle. The non-magnetic gland not only plays a role in positioning, but also provides a pre-tightening force. When the non-magnetic gland is locked, the pre-tightening force generated will connect the piezoelectric element and the mass block. Compression, so that the piezoelectric element and the mass block are in close contact on the contact surface of the piezoelectric element; when there is an external acceleration, the mass block will have a stretching or compression effect on the piezoelectric element due to inertia, and the piezoelectric element can be tested The output signal of the mass block can determine the displacement of the mass block, and then determine the value of the external acceleration. At the same time, the mass block will also be affected by the damping force of the magnetic fluid. By controlling the damping force of the magnetic fluid, the displacement of the mass block can be controlled. In order to realize the change of detection range.

The present invention is novel in structure, avoids the traditional cantilever beam structure, introduces piezoelectric elements, and uses the pre-tightening force provided by the non-magnetic gland to make the mass block and the piezoelectric element closely contact, on the one hand, it enhances the acceleration sensor Sensitivity, on the other hand, effectively increases the stiffness of the acceleration sensor, can increase the range of the acceleration sensor, and realize the large-range detection of the acceleration sensor; set two piezoelectric elements on the inclined opposite plane of the inner pyramid groove of each non-magnetic gland , the two ends of the mass block are provided with corresponding pyramidal surfaces to realize the surface contact between the mass block and the piezoelectric element; the contact surface normals of the two piezoelectric elements intersect at an oblique angle, and at the same time, the contact of each piezoelectric element The normal line of the surface forms an inclination angle with the axis of the mass block. When the acceleration sensor is subjected to horizontal acceleration or vertical acceleration, the mass block produces a horizontal displacement or a vertical displacement due to inertia, and these two displacements can be measured. It is decomposed into the displacement parallel to the contact surface of the piezoelectric element and the displacement perpendicular to the contact surface of the piezoelectric element, so that the input horizontal acceleration or vertical acceleration has a corresponding output on the piezoelectric element, so the The acceleration sensor can detect the input acceleration in the two-dimensional direction; the oblique groove is set on the mass block, which increases the effective contact area between the mass block and the magnetic fluid, and can feel the damping force of the magnetic fluid in the horizontal direction or vertical direction at the same time, and control The displacement of the mass block in the horizontal or vertical direction; two piezoelectric elements are set on each end face of the mass block. When the horizontal acceleration is input, the two piezoelectric elements on the same axis side are compressed, and the two piezoelectric elements on the other side are pressed. One piezoelectric element is released. When the vertical acceleration is input, the two piezoelectric elements on the same end face will be pressed, and the two piezoelectric elements on the other end face will be released. This differential detection method can effectively eliminate the This interference improves the accuracy of mass displacement detection; in addition, the present invention uses the controllability of the viscosity of the magnetic fluid to change the current of the excitation coil and change the magnetic field strength applied to the magnetic fluid to control the viscosity of the magnetic fluid. The purpose of this is to achieve the control of the range of the acceleration sensor and realize the characteristics of a large range. It has the characteristics of two-dimensional detection direction, large range, range controllability, high sensitivity, high reliability, intelligence, and long working life.

Description of drawings

Fig. 1 is the three-dimensional exploded schematic diagram of the quasi-two-dimensional magnetic fluid acceleration sensor of the present invention;

Fig. 2 is the structural representation of the quasi-two-dimensional magnetic fluid acceleration sensor of 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 ways

The quasi-two-dimensional magnetic fluid acceleration sensor of the present invention includes a non-magnetic cavity, a mass block, a detection device and a magnetic fluid. The non-magnetic cavity is a closed container made of non-magnetic materials; the mass block is arranged in the middle of the non-magnetic cavity. , the normal direction between the two ends of the mass block and the contact surface of the non-magnetic cavity forms a certain inclination angle with the axis of the mass block; and a detection device is provided between the contact surfaces, and between the mass block, the detection device and the non-magnetic cavity The set pre-tightening pressure is maintained between; and the cavity formed by the non-magnetic cavity and the mass block is filled with magnetic fluid; the detection device is used to detect the pressure change between the mass block and the non-magnetic cavity, and output the acceleration detection result signal.

Specifically, a mass block and multiple piezoelectric elements are placed inside a non-magnetic cavity filled with magnetic fluid composed of non-magnetic materials, and the mass block is positioned through the circumferential positioning of the inner pyramid groove of the non-magnetic gland. Keeping the same axis with the non-magnetic cavity, the piezoelectric element is pasted on the two obliquely opposite planes of the inner pyramid groove of the non-magnetic gland. The contact surface normals of the two piezoelectric elements intersect at an oblique angle. The normal line of the contact surface of the component forms an inclined angle with the axis of the mass block. The non-magnetic gland not only plays a role in the circumferential positioning of the mass block and the piezoelectric element, but also provides the necessary pre-tightening force. When the non-magnetic gland locks When tight, the pre-tightening force generated will compress the piezoelectric element and the mass block, so that the piezoelectric element and the mass block are in close contact, which is used to increase the stiffness of the acceleration sensor and also increase the measurement sensitivity of the acceleration; when When there is an external acceleration, due to the action of inertia, the mass block will stretch or compress the piezoelectric element in close contact with it: when the horizontal acceleration is input, the two piezoelectric elements on the same axis side will be compressed, and the piezoelectric element on the other side will be compressed. The two piezoelectric elements are released. When the vertical acceleration is input, the two piezoelectric elements on the same end face will be pressed, and the two piezoelectric elements on the other end face will be released. This differential detection method can effectively eliminate Various interferences improve the accuracy of mass block displacement detection. By detecting the output signal of the piezoelectric element, the mass block displacement can be determined, thereby determining the value of the external two-dimensional acceleration. At the same time, the outer wall of the mass block is equipped with multiple The inclined groove can effectively increase the effective contact area between the mass block and the magnetic fluid, and can feel the damping force of the magnetic fluid in the horizontal or vertical direction at the same time, and control the displacement of the mass block in the horizontal or vertical direction; by controlling The input current of the excitation coil can control the magnetic field of the excitation coil, and the magnetic field of the excitation coil can change the viscosity of the magnetic fluid. The change of the viscosity of the magnetic fluid will change the damping force of the magnetic fluid on the mass block, thereby controlling the displacement of the mass block. The acceleration sensor has a large range of detection, and can also dynamically control the size of the range.

The structure of the specific embodiment of the present invention is shown in Figure 1 and Figure 2, and the most basic structure of described quasi-two-dimensional acceleration sensor comprises: non-magnetic cavity, magnetic fluid 10, mass block 12 and detection device, wherein:

The non-magnetic cavity is a closed container made of non-magnetic material, which is filled with magnetic fluid 10. The non-magnetic cavity includes a non-magnetic inner cylinder 9 and a non-magnetic gland 3. In this example, the non-magnetic inner cylinder 9 is open at both ends. The non-magnetic gland 3 is installed on the end through the first screw 13, and after locking, a closed non-magnetic cavity is formed, and the inside is filled with a magnetic fluid 10; sometimes, when the processing technology allows, the non-magnetic inner cylinder 9 can be opened at one end, and the opening Install a non-magnetic gland to press the mass block 3 through the first screw 13 to form a non-magnetic cavity, which is filled with magnetic fluid 10 . At the same time, in order to better realize the sealing of the non-magnetic cavity (mainly the sealing of the magnetic fluid), a non-magnetic sealing ring 5 can be arranged between the non-magnetic inner cylinder 9 and the non-magnetic gland 3 to prevent the magnetic fluid 10 There is a leak.

In this example, the outer wall of the non-magnetic cavity 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, which is used to install the excitation coil 8. In the non-magnetic inner cylinder 9 The wall thickness is reserved in the axial direction on the two end faces for fixing the non-magnetic gland 3 .

The non-magnetic cavity in this example is cylindrical, that is, the shape of the non-magnetic inner cylinder 9 is cylindrical, with a through hole inside, and the installation wall thickness is reserved on both ends, and the outer wall of the non-magnetic inner cylinder 9 is along the axial direction. A circumferential groove is provided for installing the exciting coil 8; of course, the non-magnetic cavity can also be a prism, that is, the non-magnetic inner cylinder 9 is shaped as a prism, with holes inside and a wall thickness reserved at both ends. The outer wall of the non-magnetic inner cylinder 9 is provided with a circumferential groove along the axial direction, and the groove is used for setting 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 magnetic fluids such as magnetic fluid, magnetic composite fluid, or magnetorheological fluid, or any combination thereof. The non-magnetic inner cylinder 9 of the acceleration sensor is filled with a magnetic fluid 10 , and the mass block 12 is arranged in the magnetic fluid 10 and is subjected to the damping force of the magnetic fluid 10 . Changing the viscosity of the magnetic fluid 10 can change the damping force of the magnetic fluid 10 on the mass block 12 , thereby changing the vertical or horizontal displacement of the mass block 12 .

The detection device includes a piezoelectric element 4 composed of one or more piezoelectric sheets connected in series or in parallel, and the piezoelectric element 4 is arranged between the mass 12 and the non-magnetic cavity for detecting the mass 12 The displacement changes, and output a signal that can be detected by the subsequent detection circuit.

The contact surface between one end of the mass block 12 and the non-magnetic cavity includes two contact surfaces at 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, and the non-magnetic cavity is provided with an inner pyramid groove, and the outer positioning pyramid surface of the mass block 12 is set in the inner pyramid groove of the non-magnetic cavity to achieve circumferential positioning. Specifically:

The piezoelectric element 4 is composed of materials with piezoelectric effect such as quartz crystals, piezoelectric ceramics, piezoelectric films or other new piezoelectric materials. The piezoelectric element 4 in this example is rectangular parallelepiped sheet shape, is pasted on the oblique opposite surface of the inner pyramid groove of non-magnetic gland 3; The shape to replace. When the non-magnetic gland 3 is locked, the piezoelectric element 4 is in close contact with the mass block 12 on the contact surface under the action of the pre-tightening force, ensuring that the piezoelectric element 4 can normally sense the displacement of the mass block 12 .

The mass block 12 is made of a high specific gravity material, generally required to have a specific gravity of 14-19 g/cubic centimeter, and the mass block can be made of metal such as tungsten alloy, copper tungsten alloy and other high specific gravity alloys. The mass block can also be non-metal, as long as it meets the above range of specific gravity. The two end faces of the mass block 12 are provided with positioning cones, which are positioned by the surface of the inner pyramid groove of the non-magnetic gland 3. The mass block 12 in this example is a cuboid, and an oblique groove is arranged on the circumference of the cuboid. The inclined groove here can be helical, which is used to increase the effective contact area between the mass block 12 and the magnetic fluid 10, and can simultaneously experience the damping force of the magnetic fluid in the horizontal direction or the vertical direction; of course, the mass block 12 can also be For the cylindrical body, conical surfaces are arranged at the two end faces, and oblique grooves are arranged on the circumference of the cylindrical body, so that the same function can be realized. When the non-magnetic gland 3 is locked, the pre-tightening force generated makes the mass block 12 and the piezoelectric element 4 in close contact, which can increase the sensitivity of the acceleration sensor. At the same time, due to the material characteristics of the piezoelectric element 4, it can increase The stiffness of the acceleration sensor; when there is an external acceleration, the mass block 12 outputs a corresponding displacement due to its own inertia, and since the piezoelectric element 4 is in close contact with the mass block 12, the displacement of the mass block 12 becomes the piezoelectric element 4 input amount; since the mass block 12 is provided with oblique grooves in the circumferential direction, the damping force of the magnetic fluid can be felt in the horizontal direction or the vertical direction at the same time, when the viscosity of the magnetic fluid 10 is changed, the mass block 12 is damped by the magnetic fluid 10 The force will change, so its output displacement will also change: when the same acceleration is input, if the viscosity of the magnetic fluid 10 increases, the damping force of the mass block 12 by the magnetic fluid 10 will increase relatively, and the output displacement of the mass block 12 If the viscosity of the magnetic fluid 10 is reduced, the damping force of the magnetic fluid 10 on the mass block 12 will be relatively reduced, and the output of the mass block 12 will be relatively reduced. The displacement increases relatively, and the acceleration sensor is suitable for measuring input accelerations with relatively small values. Therefore, by controlling the viscosity of the magnetic fluid 10, the measurement 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 realize large-scale measurement.

The oblique grooves provided on the circumference of the mass block 12 in this example can also be replaced by annular blades, which also meet the above requirements.

In order to better complete the measurement work, the acceleration sensor described in this example also includes a magnetic field control device for changing the viscosity of the magnetic fluid and controlling the axial displacement of the mass block. The excitation coil 8 is arranged between the non-magnetic inner cylinder 9 and the non-magnetic sleeve 7, and the coil is wound on the groove of the non-magnetic inner cylinder 9 and kept coaxial with the non-magnetic inner cylinder 9; a coaxial coil can also be set to fix Set on the non-magnetic inner cylinder 9, the excitation coil 8 is wound in the coil fixing sleeve. The excitation coil 8 is used to generate a uniform magnetic field inside the non-magnetic inner cylinder 9. Changing the energizing current of the excitation coil 8 can change the magnetic field inside the non-magnetic inner cylinder 9: increasing the energizing current of the excitation coil 8 will increase the non-magnetic The magnetic field inside the inner cylinder 9; reducing the energizing current of the excitation coil 8 will reduce the magnetic field inside the nonmagnetic inner cylinder 9. The non-magnetic sleeve 7, the non-magnetic washer 2 and the non-magnetic gland 3 are used to isolate the connection between the magnetic field generated by the exciting coil 8 and the external magnetic field, so as to prevent the interference of the external magnetic field.

The acceleration sensor also includes an outer casing, and the non-magnetic cavity, the magnetic fluid 10, the mass 12, the detection device or the magnetic field control device are arranged in the inner cavity of the outer casing, and the outer casing specifically includes an outer sleeve 6, an upper end cover 11 and the lower end cap 1, the outer sleeve 6 and the upper end cap 11 and the lower end cap 1 are fixed by the second screw 14, and the lower end cap 1 is provided with mounting feet 15 and/or mounting holes 16.

An isolation sleeve is provided between the outer shell and the non-magnetic cavity, which is used to isolate the connection between the magnetic field control device and the external magnetic field, and suppress the interference of the external magnetic field. The spacer includes a non-magnetic sleeve 7 and a non-magnetic washer 2 .

The acceleration sensor also includes a detection and control device, which is used to control the input current of the excitation coil according to the acceleration detection result signal output by the detection device, so as to control the internal magnetic field of the excitation coil.

The operating principle of the acceleration sensor of the present invention is as follows:

As shown in Figure 1, Figure 2 and Figure 3, the non-magnetic inner cylinder 9 is filled with a magnetic fluid 10, and in the magnetic fluid 10, the mass 12 and the piezoelectric element 4 pass through the inner pyramidal groove of the non-magnetic gland 3 Positioning, when the non-magnetic gland 3 is locked, the pre-tightening force generated makes the mass block 12 and the piezoelectric element 4 closely contact, and the mass block 12 is also subjected to the damping force of the magnetic fluid 10, and the mass block 12 is provided with an oblique groove , increase the effective contact area with the magnetic fluid 10, you can feel the damping force of the magnetic fluid in the horizontal direction or vertical direction at the same time, because the non-magnetic gland 3 is provided with a sealing ring 5, so that the magnetic fluid 10 will not overflow; in the non-magnetic The outer wall of the inner cylinder 9 is provided with a circumferential groove along the axial direction, and the excitation coil 8 is arranged in the circumferential groove to provide a uniform magnetic field. The excitation coil 8 is provided with a non-magnetic sleeve 9, and the non-magnetic gland 3 is provided with a The magnetic washer is used to isolate the connection between the magnetic field of the exciting coil 8 and the external magnetic field, so as to prevent the interference of the external magnetic field.

When there is an external acceleration, the mass block 12 outputs a corresponding displacement due to its own inertia. Since the piezoelectric element 4 is in close contact with the mass block 12, the displacement of the mass block 12 becomes the input amount of the piezoelectric element 4: when When the vertical acceleration is input, the mass block 12 produces a displacement in the vertical direction due to the inertial effect. At this time, the two piezoelectric elements 4 on the same end face are compressed, and the piezoelectric element 4 on the other end face is relaxed. The mass block 12 The displacement generated in the vertical direction will be decomposed into a component perpendicular to the contact surface of the piezoelectric element 4 and a component parallel to the contact surface of the piezoelectric element 4. At this time, the output signal of the two piezoelectric elements 4 on the same end surface The signs are the same, and the signs of the output signals of the piezoelectric elements on different end faces are opposite. Therefore, by detecting the output of the piezoelectric element 4, the value of the vertical acceleration can be determined; when the horizontal acceleration is input, the mass block 12 due to inertia acts on Displacement is generated in the horizontal direction. At this time, the two piezoelectric elements 4 on the same axis side are compressed, and the two piezoelectric elements 4 on the other axis side are relaxed. The displacement generated by the horizontal direction of the mass block 12 will be decomposed. It is the component perpendicular to the contact surface of the piezoelectric element 4 and the component parallel to the contact surface of the piezoelectric element 4. At this time, the signs of the output signals of the two piezoelectric elements 4 on the same axis side are the same, and the piezoelectric elements 4 on the different axis sides have the same sign. The output signals of electrical components are opposite in sign. The magnitude of the output signal of the piezoelectric element 4 can determine the value of the input acceleration, and by comparing the signs of the output signals of different piezoelectric elements, it can be determined whether the input acceleration is a vertical acceleration or a horizontal acceleration, thereby realizing the two-dimensionality of the detection direction.

By controlling the energizing current of the excitation coil 8 and changing the magnitude of the generated magnetic field, the viscosity of the magnetic fluid 10 can be changed. Since the mass block 12 is subjected to the damping force of the magnetic fluid 10, the damping force effect of the mass block 12 can be changed, thereby changing The output displacement of mass block 12. When the same external acceleration is input, changing the energizing current of the excitation coil 8 and changing the viscosity of the magnetic fluid 10 can change the displacement of the mass block 12, thereby realizing the range controllability of the acceleration sensor. At the same time, due to the mass The block 12 is provided with oblique grooves in the circumferential direction, which can feel the damping force of the magnetic fluid in the horizontal direction or the vertical direction at the same time, so the range controllability of the acceleration sensor in the two-dimensional direction can be realized; if the magnetic fluid 10 is greatly improved Viscosity, when the same external acceleration is input, the displacement of the mass block 12 will decrease. Therefore, the measurement of a large range of acceleration can be realized.

If the output of the piezoelectric element 4 is further input to the control circuit of the exciting coil 8 in the form of feedback, the control circuit can automatically adjust the energizing current of the exciting coil 8 according to the output of the piezoelectric element 4, and then the acceleration can be realized. Sensor intelligence.

The structure of the acceleration sensor described in this example no longer adopts the traditional cantilever beam working method, but instead introduces a piezoelectric element as an elastic element, which improves the measurement sensitivity of the acceleration sensor, and the elastic element no longer bends, Physical deformation such as torsion also improves the working life and reliability of the acceleration sensor.

Therefore the present invention has following advantage and beneficial effect:

1. The invention is novel in 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 oblique contact structure between the mass block and the piezoelectric element is adopted in the present invention, which changes the working principle that the axis of the mass block and the normal line of the contact surface of the piezoelectric element in the traditional one-dimensional piezoelectric acceleration sensor are parallel to the normal line of the contact surface of the piezoelectric element to achieve two-dimensional detection. The purpose of inputting the acceleration in the dimensional direction, thus realizing the two-dimensionality of the detection direction;

3. The present invention adopts the characteristics of the controllability of the viscosity of the magnetic fluid. By controlling the energizing current of the excitation coil, the magnetic field strength applied to the magnetic fluid is changed to achieve the purpose of controlling the viscosity of the magnetic fluid, thereby realizing the controllability of the range of the acceleration sensor;

4. The present invention introduces a multi-groove mass block and a piezoelectric element, and by increasing the viscosity of the magnetic fluid, the detection of a large range of input acceleration can be realized;

5. In the present invention, the differential connection of the output signal of the piezoelectric element is adopted, which can effectively eliminate various interferences and improve the detection accuracy;

6. The present invention eliminates the elastic deformation of the elastic element in the process of bending and torsion, and improves the working reliability of the acceleration sensor;

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by 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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