CN108217590B - Three-axis pedestal excitation device for testing dynamic characteristics of MEMS microstructures - Google Patents

Abstract

The invention discloses a three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures, which includes sleeves, stacked piezoelectric ceramics, pressure sensors, upper and lower connecting blocks, steel balls and MEMS microstructures; The cylinder is equipped with a support plate and an electric screw drive mechanism connecting the nut and the lower connecting block; the upper and lower connecting blocks are respectively provided with spherical grooves and conical grooves for holding steel balls; stacked piezoelectric ceramics It is clamped between the pressure sensor and the elastic supporting piece; ball plungers are uniformly connected to the upper connecting block, and the outer ends of the ball plungers push into the rectangular grooves on the inner wall of the sleeve. The device can more flexibly apply different sizes of pre-tightening force to the stacked piezoelectric ceramics, so that the obtained pre-tightening force measurement value is more accurate, and the adjustment process of compensating the parallelism error of the two working surfaces of the stacked piezoelectric ceramics can be changed. It is smoother and smoother, reducing the shear force between the layers of the stacked piezoelectric ceramics, which is convenient for testing the dynamic characteristic parameters of the MEMS microstructure.

Description

Three-axis pedestal excitation device for testing dynamic characteristics of MEMS microstructures

technical field

The invention belongs to the technical field of micromechanical electronic systems, and in particular relates to a three-axis base excitation device used for testing the dynamic characteristics of MEMS microstructures.

Background technique

Due to the advantages of low cost, small size and light weight, MEMS microdevices have broad application prospects in many fields such as automobile, aerospace, information communication, biochemistry, medical treatment, automatic control and national defense. For many MEMS devices, the micro-displacement and micro-deformation of their internal microstructures are the basis for the realization of device functions. Therefore, accurate testing of dynamic characteristic parameters such as the amplitude, natural frequency, and damping ratio of these microstructures has become the key to developing MEMS products. important content.

In order to test the dynamic characteristic parameters of the microstructure, it is first necessary to make the microstructure vibrate, that is, to excite the microstructure. Due to the small size, light weight and high natural frequency of MEMS microstructures, the excitation methods and excitation devices in traditional mechanical mode testing cannot be applied to the vibration excitation of MEMS microstructures. In the past thirty years, researchers at home and abroad have conducted a lot of explorations on the vibration excitation methods of MEMS microstructures, and have developed some excitation methods and corresponding excitation devices that can be used for MEMS microstructures. Among them, the base excitation device using stacked piezoelectric ceramics as the excitation source has the advantages of large excitation bandwidth, simple device, easy operation, and strong applicability, so it has been widely used in the field of MEMS microstructure dynamic characteristic testing. In the article "A base excitation test facility fordynamic testing of microsystems", David et al. introduced a base excitation device based on piezoelectric ceramics. In this device, stacked piezoelectric ceramics are directly bonded on a fixed base. The stacked piezoelectric ceramics is a multi-layer bonding structure, so the stacked piezoelectric ceramics can withstand a large pressure, but it cannot bear the tensile force. The tensile force will cause the damage of the stacked piezoelectric ceramics. When the stacked piezoelectric ceramics are in When in use, applying a certain pre-tightening force is beneficial to prolong the service life of stacked piezoelectric ceramics, but this device does not consider the above problems; Wang et al. in the article "Dynamic characteristic testing forMEMS micro-devices with base excitation" This paper introduces a base excitation device based on piezoelectric ceramics. In this device, the problem of applying a certain pre-tightening force to the stacked piezoelectric ceramics is considered. Electric ceramics, and the size of the pre-tightening force can be changed by turning the adjusting screw, but this device does not take into account that when the above-mentioned mechanism is used to apply the pre-tightening force to the stacked piezoelectric ceramics, due to the two working surfaces of the stacked piezoelectric ceramics The parallelism error will generate shear force between the layers of the stacked piezoelectric ceramics, which will cause mechanical damage to the stacked piezoelectric ceramics. In addition, the device cannot measure the applied preload. If the size is not adjusted properly, it will also cause mechanical damage to the stacked piezoelectric ceramics; the Chinese invention patent with the publication number of CN101476970A discloses a base excitation device based on piezoelectric ceramics, in which cross spring sheets are stacked Stack piezoelectric ceramics to apply pre-tightening force, and reduce the shear force on piezoelectric ceramics by installing the bottom of stacked piezoelectric ceramics on a movable base structure. In addition, a pressure sensor is also provided in the device. It is used to detect the pre-tightening force applied to the piezoelectric ceramics and the output force of the stacked piezoelectric ceramics during operation. But this device still has following shortcoming:

1. The movable base structure of the device is composed of an upper connection block, a steel ball and a lower connection block. The steel ball, the upper connection block and the lower connection block are in line contact. When it is necessary to compensate the top surface of the stacked piezoelectric ceramics and the When the movable base structure is adjusted by itself due to the parallelism error of the two working surfaces on the bottom surface, the steel ball cannot rotate smoothly, and may even be stuck;

2. There is no direct connection between the upper connection block and the lower connection block and the sleeve, but are installed in the sleeve in turn by means of clearance fit. If the parallelism error of the two working surfaces of the stacked piezoelectric ceramics is large , there is not enough space to adjust the movable base structure;

3. The pressure sensor is installed at the bottom of the lower connecting block. Since the movable base structure is self-adjusted, there is a certain inclination between the bottom of the lower connecting block and the working surface of the piezoelectric ceramic, so the pre-tightening force measured by the pressure sensor Or the output force of piezoelectric ceramics is not accurate; in addition, if the movable base structure causes the upper coupling block or the lower coupling block to contact the sleeve after adjustment, the error of the measurement result will further increase;

4. In the device, one side of the cross spring is used to compress the stacked piezoelectric ceramics, and the other side of the cross spring is bonded to the micro device for testing. When the piezoelectric ceramics are working, the deformation of the cross spring is relatively large. Cause the colloid between the micro-device and the cross spring to crack, causing the micro-device to fall off;

5. In this device, gaskets of different thicknesses are used to change the magnitude of the pre-tightening force applied to the stacked piezoelectric ceramics, resulting in a complicated adjustment process and insufficient flexibility.

Contents of the invention

The technical problem to be solved by the present invention is to provide a three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures. The obtained preload measurement value is more accurate, which can make the adjustment process of compensating the parallelism error of the two working surfaces of the stacked piezoelectric ceramics smoother and smoother, and greatly reduces the shear between the layers of the stacked piezoelectric ceramics. The shearing force can avoid the falling off of the micro-device used for testing, and it is convenient to test the dynamic characteristic parameters of the MEMS microstructure.

In order to solve the above problems, the present invention adopts the following technical solutions:

A three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures, including a sleeve, in which there are stacked piezoelectric ceramics, pressure sensors, and an upper connection block, a steel ball and a lower connection block. The movable base is provided with elastic supports and MEMS microstructures on the sleeve, which is characterized by:

An annular top plate is provided on the sleeve, and the MEMS microstructure is mounted on the annular top plate through an elastic support;

A support plate is provided at the lower part of the sleeve, and an electric screw transmission mechanism is installed in the center of the support plate along the vertical direction. The screw nut of the electric screw transmission mechanism is connected with the lower connection block to drive the lower connection block to move up and down;

Spherical grooves and conical grooves are respectively provided on the opposite surfaces of the upper coupling block and the lower coupling block, and the radius of the steel ball is smaller than the radius of curvature of the spherical grooves and is clamped between the spherical grooves and the conical grooves Between the upper and lower connecting blocks, an adjustment gap is formed through steel balls; the pressure sensor is embedded in the center hole on the top surface of the upper connecting block, and the stacked piezoelectric ceramics are clamped between the pressure sensor and the elastic support between;

Ball plungers are evenly distributed on the outer edge of the upper connection block, and the steel balls at the outer ends of the ball plungers are pushed into the rectangular grooves uniformly distributed on the inner wall of the sleeve along the circumferential direction, which are used to assist the movable base to compensate for stacking Adjustment of the parallelism error of the two working surfaces of piezoelectric ceramics;

Guide shafts are evenly distributed in the sleeve along the circumferential direction, and the guide shafts pass through the uniform guide holes arranged on the flange plate at the lower end of the lower connection block through clearance fit to ensure the levelness of the lower connection block when moving up and down.

As a further preference, adjusting rods are evenly distributed around the outer edge of the upper coupling block, and the adjusting rods are respectively passed through long holes uniformly distributed on the sleeve wall along the circumferential direction; for realizing the reset of the upper coupling block after the test.

As a further preference, the elastic support member is composed of a cylindrical pressing piece and three support arms whose circumference is evenly distributed on the outer edge of the pressing piece, the thickness of the supporting arms is smaller than the thickness of the pressing piece; The amount of deformation of the chip can avoid the MEMS microstructure falling off due to the cracking of the colloid.

As a further preference, the elastic support is supported and fixed on the annular top plate by three pillars.

As a further preference, the outer edge of the upper coupling block is windmill-shaped, and the outer edge has three first and second side edges uniformly distributed around the circumference, the first side edge and the adjacent second side edge The angle between the surfaces is 30 degrees, and the radius of the first side facet from the center hole axis is smaller than the radius of the second side facet from the center hole axis, and the gap between the second side facet and the inner wall of the sleeve is 5-10mm.

As a further preference, there are three ball plungers and they are respectively connected in the installation holes of each first side edge.

As a further preference, there are three adjusting rods and they are respectively connected in the installation holes of each second side edge.

As a further preference, a mounting sleeve is fastened on the upper end of the stacked piezoelectric ceramics, and the elastic support is pressed on the mounting sleeve to avoid the stacked piezoelectric ceramics caused by the roughness of the top working surface of the stacked piezoelectric ceramics. Poor contact between ceramic and elastic supports.

As a further preference, the centerline of the elongated hole and the centerline of the rectangular groove are parallel to the axis of the sleeve, and the centerline of each elongated hole and the centerline of the nearest rectangular groove to the elongated hole are clamped. The central angle is 30 degrees.

As a further preference, the central angle formed by the central line of the elongated hole and the axis of the guide shaft closest to the elongated hole and the axis of the sleeve is 30 degrees.

As a further preference, the guide shafts are uniformly connected between the annular top plate and the support plate.

The beneficial effects of the present invention are:

1. Since the radius of the steel ball is smaller than the radius of curvature of the spherical groove and it is clamped between the spherical groove and the tapered groove, a point contact is formed between the steel ball and the upper coupling block, and a point contact is formed between the steel ball and the lower coupling block. For line contact, when it is necessary to compensate the parallelism error of the two working surfaces of the stacked piezoelectric ceramics to adjust the movable base, the upper connecting block will rotate with the contact point with the steel ball as the center of rotation, and the adjustment process is smooth and smooth, without There will be a problem of the steel ball being stuck, which greatly reduces the shear force between the layers of the stacked piezoelectric ceramics.

2. Since the ball plunger is evenly distributed on the outer edge of the upper connection block, the steel balls at the outer end of the ball plunger are pushed into the rectangular grooves uniformly distributed on the inner wall of the sleeve along the circumferential direction. When it is necessary to compensate for the stacking pressure When the parallelism error of the two working surfaces of the electroceramic is used to adjust the movable base, the upper connecting block can swing in different directions through the cooperation of the spring in the ball plunger and the steel ball, and the adjustable space is larger.

3. Since the pressure sensor is embedded in the center hole on the top surface of the upper connecting block, the stacked piezoelectric ceramics are clamped between the pressure sensor and the elastic support, so when the pre-tightening force is applied to the stacked piezoelectric ceramics , which avoids the interference of the movable base structure on the pressure sensor, and can obtain more accurate pre-tightening force data; when the stacked piezoelectric ceramics work, the measured value of the excitation force obtained is also more accurate.

4. Since the electric screw drive mechanism is installed vertically in the center of the support plate, the screw nut of the electric screw drive mechanism is connected to the lower connecting block. When it is necessary to apply different sizes of pretightening force to the stacked piezoelectric ceramics It can be realized by driving the movable base to move through the electric screw transmission mechanism, and the adjustment process is simple and flexible.

Description of drawings

Fig. 1 is a schematic diagram of the three-dimensional structure of the present invention.

Figure 2 is a top view of the present invention.

Fig. 3 is a cross-sectional view along line A-A of Fig. 2 .

Fig. 4 is a B-B sectional view of Fig. 2 .

Fig. 5 is a top view of the present invention with the annular top plate removed.

Fig. 6 is a schematic perspective view of the upper connection block.

Fig. 7 is a schematic diagram of the structure of the elastic support.

In the figure: 1, sleeve, 101, rectangular groove, 102, long hole, 2, annular top plate, 3, bottom plate, 4, MEMS microstructure, 5, microstructure mounting plate, 6, elastic support member, 601, pressure Sheet, 602, support arm, 7, pillar, 8, installation sleeve, 9, ball plunger, 10, stacked piezoelectric ceramics, 11, pressure sensor, 12, adjustment rod, 13, upper connection block, 1301, spherical surface Groove, 1302, first side face, 1303, second side face, 14, steel ball, 15, lower connection block, 1501, tapered groove, 16, screw nut, 17, support plate, 18, straight line Stepper motor, 19, guide shaft, 20, axle sleeve, 21, leading screw.

Detailed ways

As shown in Figures 1 to 7, the present invention relates to a three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures, including a hollow sleeve 1, and stacked piezoelectric ceramics are arranged in the sleeve 1. 10. The pressure sensor 11 and the movable base composed of the upper coupling block 13 , the steel ball 14 and the lower coupling block 15 , and the elastic support 6 and the MEMS microstructure 4 are arranged on the sleeve 1 .

An annular top plate 2 and a bottom plate 3 are respectively fixed on the upper and bottom surfaces of the sleeve 1 by bolts, and the MEMS microstructure 4 is installed on the annular top plate 2 through an elastic support 6; 601 and three support arms 602 whose circumference is evenly distributed on the outer edge of the pressing sheet 601. The thickness of the supporting arms 602 is smaller than that of the pressing sheet 601; Crack and fall off. The three support arms 602 of the elastic support member 6 are supported and fixed on the annular top plate 2 through three pillars 7 with screws, and are on the same axis as the sleeve 1 . The MEMS microstructure 4 is fixed on the center of the upper surface of the pressing piece 601 of the elastic support 6 through the microstructure mounting plate 5 .

A support plate 17 is fixed by screws at the bottom step of the sleeve 1, and an electric screw drive mechanism is installed in the center of the support plate 17 along the vertical direction. The lead screw 21 of the output shaft of the stepping motor 18 and the screw nut 16 are formed, wherein the linear stepping motor 18 is installed on the bottom surface of the support plate 17, the upper end of the screw screw 21 is inserted into the center hole of the bottom surface of the lower connecting block 15, and the screw nut 16 is connected with the lower The blocks 15 are connected by screws uniformly distributed on the circumference, and are used to drive the lower connecting block 15 to move up and down.

A spherical groove 1301 and a tapered groove 1501 are respectively provided at the center of the opposite surface of the upper coupling block 13 and the lower coupling block 15, and the radius of the steel ball 14 is smaller than the radius of curvature of the spherical groove 1301 and is clamped on the spherical surface. Between the groove 1301 and the tapered groove 1501, an adjustment gap is formed between the upper coupling block 13 and the lower coupling block 15 through the steel ball 14, and the size of the adjustment gap is 2-5 mm.

The pressure sensor 11 is embedded and bonded in the center hole of the top surface of the upper connecting block 13, the stacked piezoelectric ceramic 10 is cylindrical and the lower end is bonded to the pressure sensor 11, and the two ends of the stacked piezoelectric ceramic 10 are clamped Hold between the pressure sensor 11 and the pressure piece 601 of the elastic support member 6 . A mounting sleeve 8 is fastened and bonded to the upper end of the stacked piezoelectric ceramics 10, and the pressing piece 601 of the elastic support member 6 is pressed on the mounting sleeve 8 to avoid roughness of the top working surface of the stacked piezoelectric ceramics 10. The problem of poor contact between the stacked piezoelectric ceramics 10 and the elastic support 6 caused by unevenness.

The outer edge of the upper coupling block 13 is windmill-shaped, and the outer edge has three circumferentially evenly distributed first side edges 1302 and second side edges 1303, the first side edges 1302 and the adjacent second side edges The included angle of the surface 1303 is 30 degrees, and the radius of the first side edge surface 1302 from the center hole axis is smaller than the radius of the second side edge surface 1303 from the center hole axis, and the gap between the second side edge surface 1303 and the inner wall of the sleeve 1 is 5-10mm. The outer edge of the upper coupling block 13 is uniformly connected with ball plungers 9, and the ball plungers 9 are three and are respectively threaded in the mounting holes of each first side edge surface 1302, the ball studs The steel balls at the outer end of the plug 9 are pushed into three rectangular grooves 101 uniformly distributed on the inner wall of the sleeve 1 along the circumferential direction, and are used to assist the movable base to compensate for the parallelism error adjustment of the two working surfaces of the stacked piezoelectric ceramics 10 .

Adjusting rods 12 are uniformly connected to the outer circumference of the upper coupling block 13 , and there are three adjusting rods 12 connected radially in the installation holes of each second side edge 1303 . The adjusting rods 12 respectively pass through three long holes 102 uniformly distributed on the wall of the sleeve 1 along the circumferential direction, so as to realize the reset of the upper coupling block 13 after the test. The center line of the elongated hole 102 and the center line of the rectangular groove 101 are all parallel to the axis of the sleeve 1, and the center line of each elongated hole 102 and the center line of the nearest rectangular groove 101 to the elongated hole 102 The central angle of the clip is 30 degrees.

Three guide shafts 19 are evenly distributed along the circumferential direction in the sleeve 1 , and the two ends of the guide shafts 19 are respectively connected between the annular top plate 2 and the support plate 17 by bolts. The guide shaft 19 passes through the evenly distributed guide holes arranged on the flange plate at the lower end of the lower coupling block 15 through clearance fit, so as to ensure the levelness of the lower coupling block 15 when moving up and down. Axle sleeves 20 are fitted respectively in the guide holes at the lower end of the lower coupling block 15 . The central angle formed by the center line of the long hole 102 and the axis of the guide shaft 19 closest to the long hole 102 and the axis of the sleeve 1 is 30 degrees.

When working, the linear stepping motor 18 is firstly controlled to push up the movable base composed of the upper connecting block 13, the steel ball 14 and the lower connecting block 15 through the transmission of the lead screw 21 and the screw nut 16 to apply a pre-load to the stacked piezoelectric ceramics 10. tightening force, while monitoring the pre-tightening force data measured by the pressure sensor 11, when the size of the pre-tightening force reaches the set value, the linear stepper motor 18 is controlled to stop working. Then, an external power supply is used to apply a pulse signal or a frequency sweep signal between the two electrodes of the stacked piezoelectric ceramics 10, and the inverse piezoelectric effect of the stacked piezoelectric ceramics 10 is used to excite the MEMS microstructure 4. The contact vibration measuring device detects the vibration response of the MEMS microstructure 4 , and the pressure sensor 11 is used to detect the output force of the stacked piezoelectric ceramics 10 . Finally, after the excitation of the MEMS microstructure 4 is completed, the linear stepping motor 18 is controlled to drive the lower coupling block 15 and the steel ball 14 to move downward, and then the three adjusting rods 12 are manually adjusted to drive the upper coupling block 13 to move downward, so that The mounting sleeve 8 on the top of the stacked piezoelectric ceramics 10 is separated from the elastic support member 6 to prevent the stacked piezoelectric ceramics 10 from being under stress all the time.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Therefore, the invention is not limited to the specific details and examples shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims (10)

1. A three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures, including a sleeve, in which a stack of piezoelectric ceramics, a pressure sensor, and an upper coupling block, a steel ball and a lower coupling block are arranged. The formed movable base is provided with elastic supports and MEMS microstructures on the sleeve, which is characterized by: An annular top plate is provided on the sleeve, and the MEMS microstructure is mounted on the annular top plate through an elastic support; A support plate is provided at the lower part of the sleeve, and an electric screw transmission mechanism is installed in the center of the support plate along the vertical direction. The screw nut of the electric screw transmission mechanism is connected with the lower connection block to drive the lower connection block to move up and down; Spherical grooves and conical grooves are respectively provided on the opposite surfaces of the upper coupling block and the lower coupling block, and the radius of the steel ball is smaller than the radius of curvature of the spherical grooves and is clamped between the spherical grooves and the conical grooves Between the upper and lower connecting blocks, an adjustment gap is formed through steel balls; the pressure sensor is embedded in the center hole on the top surface of the upper connecting block, and the stacked piezoelectric ceramics are clamped between the pressure sensor and the elastic support between; Ball plungers are evenly distributed on the outer edge of the upper connection block, and the steel balls at the outer ends of the ball plungers are pushed into the rectangular grooves uniformly distributed on the inner wall of the sleeve along the circumferential direction, which are used to assist the movable base to compensate for stacking Adjustment of the parallelism error of the two working surfaces of piezoelectric ceramics; Guide shafts are evenly distributed in the sleeve along the circumferential direction, and the guide shafts pass through the uniform guide holes arranged on the flange plate at the lower end of the lower connection block through clearance fit to ensure the levelness of the lower connection block when moving up and down. 2. The three-axis base excitation device for MEMS microstructure dynamic characteristic test according to claim 1 is characterized in that: the outer edge circumference of the upper coupling block is uniformly connected with adjustment rods, and the adjustment rods are respectively arranged along the circumferential direction. The long holes evenly distributed on the wall of the sleeve pass through; it is used to realize the reset of the upper coupling block after the test. 3. The three-axis base excitation device for MEMS microstructure dynamic characteristic test according to claim 1, characterized in that: said elastic support is made of a cylindrical pressing piece and the circumference is evenly distributed on the pressing piece outer edge The three supporting arms are composed of three supporting arms, and the thickness of the supporting arms is smaller than the thickness of the pressing sheet; to reduce the deformation of the cylindrical pressing sheet, and prevent the MEMS microstructure from falling off due to the cracking of the colloid. 4. The three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures according to claim 3, characterized in that: the elastic support is supported and fixed on the annular top plate by three pillars. 5. The three-axis base excitation device for MEMS microstructure dynamic characteristic test according to claim 2, characterized in that: the outer edge of the upper coupling block is windmill-shaped, and the outer edge has three circumferentially uniform The first side facet and the second side facet, the angle between the first side facet and the adjacent second side facet is 30 degrees, and the radius of the first side facet from the central hole axis is smaller than the second side facet The radius of the surface from the axis of the central hole, and the gap between the second side edge surface and the inner wall of the sleeve are 5-10mm. 6. The three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures according to claim 5, characterized in that: the ball plungers are three and are respectively connected to each of the first side facets. inside the mounting hole. 7. The three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures according to claim 6, characterized in that: the adjustment rods are three mounting holes connected to each second side facet respectively Inside. 8. The three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures according to claim 1, characterized in that: a mounting sleeve is fastened on the upper end of the stacked piezoelectric ceramics, and the elastic support is pressed against the mounting sleeve. The sleeve is used to avoid the problem of poor contact between the stacked piezoelectric ceramics and the elastic support due to the roughness of the top working surface of the stacked piezoelectric ceramics. 9. The three-axis base excitation device for testing the dynamic characteristics of MEMS microstructures according to claim 2, characterized in that: the centerline of the long hole and the centerline of the rectangular groove are all parallel to the axis of the sleeve , and the central angle formed by the centerline of each elongated hole and the centerline of the nearest rectangular groove to the elongated hole and the axis of the sleeve is 30 degrees. 10. The three-axis base excitation device for MEMS microstructure dynamic characteristic test according to claim 9, characterized in that: the center line of the elongated hole and the axis of the guide shaft closest to the elongated hole and the distance between the sleeve The central angle between the axes is 30 degrees.