Anti-overload triaxial MEMS (Micro Electro Mechanical System) gyroscope

Abstract

The utility model discloses an anti-overload triaxial MEMS (micro-electromechanical system) gyroscope which comprises a vibration mass block, a driving beam, a detection beam, a multi-stage buffer stop structure, an anchor point, an upper cover plate and a lower cover plate. The driving beam is periodically deformed through the inverse piezoelectric effect and drives the vibration mass block to reciprocate. Multi-stage buffer stop structures are distributed on the periphery of the vibration mass block, and the upper cover plate and the lower cover plate are provided with flexible stop structures, so that the movable structure can be prevented from being damaged due to excessive deformation. According to the three-axis angular velocity sensor, the measurement of three-axis angular velocity is realized on a single chip, and meanwhile, overload protection structures are arranged in three axial directions, so that the three-axis angular velocity sensor has relatively strong overload resistance.

Description

TECHNICAL FIELD

[0001] The utility model relates to MEMS gyroscope technical field, especially a kind of anti-overload three-axis MEMS gyroscope. BACKGROUND

[0002] With the continuous development of micromechanical processing technology and measurement and control technology, the precision of MEMS gyroscope is continuously improved, combined with small size, light weight, low power consumption, mass production and other characteristics, has been widely used in automotive electronics, aerospace and other fields.In the application of some special equipment, usually requires the assembled gyroscope has higher integration, smaller size and better anti-overload capacity, needs a single-chip multi-axis integrated anti-overload MEMS gyroscope to meet the demand.

[0003] In prior art, MEMS gyroscope is mostly electrostatic driving, capacitive detection mode, since electrostatic force action distance is shorter, therefore requires that the size and spacing of capacitor plate are extremely small (submicron level), and breakage is prone to occur when impacted.

[0004] To cope with high impact or strong vibration application environment, part of MEMS gyroscope chip is also designed with stop structure. The stop structure designed in the periphery of mass block in the patent such as "a kind of anti-high overload MEMS gyroscope" is fixed stop.The disadvantage of fixed stop is that when mass block is impacted and contacted with fixed stop, since the rigidity of fixed stop is large, it is not easy to deform greatly, and collision energy is difficult to be absorbed, which is easy to cause failure such as breakage. SUMMARY

[0005] In view of the deficiencies of prior art, the utility model provides a kind of anti-overload three-axis MEMS gyroscope, three-axis angular velocity detection can be realized on single chip, and the integration is higher, and the volume is smaller.The mode of inverse piezoelectric effect driving and piezoresistive effect detection is used, compared with the MEMS gyroscope using electrostatic driving and capacitive detection, the problem of breakage due to small size and small gap of comb structure can be avoided.Meanwhile, multi-stage buffer stop structure is used to limit the displacement of vibrating mass block in plane, flexible stop structure is used in upper cover plate and lower cover plate to limit the displacement of vibrating mass block in direction perpendicular to plane, and the anti-overload capacity is further improved.

[0006] In order to achieve the above purpose, the technical scheme of the utility model is as follows:

[0007] The utility model provides a kind of anti-overload three-axis MEMS gyroscope, comprising: vibrating mass, drive beam, detection beam, multistage buffer stop structure, anchor point, upper cover plate, lower cover plate;The number of vibrating mass is 4, and the distribution mode of vibrating mass is orthogonal symmetric distribution, each vibrating mass is connected with 1 pair of drive beam and 3 pairs of detection beam respectively, and 3 pairs of multistage buffer stop structure are distributed around each vibrating mass;The multistage buffer stop structure includes fixed beam and movable beam, and fixed beam and movable beam are alternately distributed in turn, and fixed beam is fixed on the anchor point, and movable beam is fixed on the vibrating mass, and there is gap between fixed beam and movable beam.

[0008] The drive beam side has a piezoelectric material film, which is driven by an external drive circuit to move perpendicular to the drive beam direction.

[0009] The multistage buffer stop structure includes 2 fixed beams and 3 movable beams, and the fixed beams and movable beams are alternately distributed in turn, the first fixed beam is located between the first movable beam and the second movable beam, the second fixed beam is located between the second movable beam and the third movable beam, the gap width between the first fixed beam and the first movable beam and the second movable beam is equal, and the gap width between the second fixed beam and the second movable beam and the third movable beam is equal.

[0010] The gap width between the first fixed beam and the first movable beam and the second movable beam of the multistage buffer stop structure is less than the gap width between the second fixed beam and the second movable beam and the third movable beam.

[0011] The detection beam includes a pair of out-of-plane motion detection beam and two pairs of in-plane motion detection beam, the out-of-plane motion detection beam is formed by surface doping to form a surface force sensitive resistor, and the in-plane motion detection beam is formed by side doping to form a side force sensitive resistor.

[0012] The upper cover plate and the lower cover plate are provided with flexible stop structures corresponding to the areas of the four vibrating masses, the flexible stop structures are "convex" type suspensions, the bottom edge of each "convex" type suspension is fixed on the cover plate, and the remaining edges are suspended, and the "convex" type suspension is provided with a circular elastic protrusion structure. Advantages

[0013] Through the above scheme, the utility model has the following advantages:

[0014] The utility model adopts the mode of inverse piezoelectric effect driving and piezoresistive effect detection, and the overall structure is relatively simple. Compared with the MEMS gyroscope using electrostatic driving and capacitance detection, the comb structure is not needed, and the problem of easy collision and fracture caused by small size and gap of the comb structure can be avoided. Compared with the MEMS gyroscope using electromagnetic force driving, no additional magnetic field is needed, the structure is simpler and the volume is smaller.

[0015] The utility model discloses a multistage buffer stop structure, through the progressive buffer stop mode to avoid the excessive displacement of the vibration mass block in the plane, and through the flexible stop structure of upper cover plate and lower cover plate, limit the excessive displacement of the vibration mass block in the vertical plane direction. The displacement range of the vibration mass block in three axial directions is limited, can reduce the damage failure caused by excessive deformation when being impacted, has stronger anti-overload capacity.

[0016] The utility model discloses a different deflection mode of 4 vibration mass blocks to detect three axial angular velocities, and the deflection mode of the vibration mass block under the influence of different axial angular velocities is mutually orthogonal, and through 3 pairs of independent detection beams to detect the deflection of the vibration mass block in the plane and the deflection in the vertical plane direction, can effectively reduce the coupling between different axes. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is the schematic diagram of an embodiment of the utility model.

[0018] Figure 2 It is the multistage buffer stop structure schematic diagram of an embodiment of the utility model.

[0019] Figure 3 It is the upper cover plate and lower cover plate schematic diagram of an embodiment of the utility model.

[0020] Figure 4 It is the drive mode schematic diagram of an embodiment of the utility model.

[0021] Sign significance: 100, vibration mass block;200, drive beam;300, detection beam, 310, in-plane deformation detection beam, 320, out-of-plane deformation detection beam;400, multistage buffer stop structure, 410, fixed beam, 411, first fixed beam, 412, second fixed beam, 420, movable beam, 421, first movable beam, 422, second movable beam, 423, third movable beam;500, anchor point;600, upper cover plate, 610, " convex " shape suspension plate, 620, circular elastic convex point structure;700, lower cover plate. DETAILED DESCRIPTION

[0022] The specific embodiment of the utility model is further explained below in combination with the drawings.

[0023] For example, Figure 1As shown, the utility model provides a kind of anti-overload three-axis MEMS gyro, it is characterized in that, including: vibrating mass 100, drive beam 200, detection beam 300, multistage buffer stop structure 400, anchor point 500.The number of vibrating mass 100 is 4, and the distribution mode of vibrating mass 100 is orthogonal symmetric distribution, each vibrating mass 100 is connected with 1 pair of drive beam 200 and 3 pairs of detection beam 300 respectively, and each vibrating mass 100 is distributed with 3 pairs of multistage buffer stop structure 400 around.

[0024] The side of drive beam 200 has piezoelectric material film, piezoelectric material film is driven under the excitation of external drive circuit and drives drive beam 200 to move in plane perpendicular to the direction of drive beam 200, to further drive vibrating mass 100 connected with drive beam 200 to move.By reasonably designing external drive circuit, the movement mode of 4 pairs of drive beam 200 is identical, to drive 4 vibrating mass 100 to generate identical movement mode.

[0025] Detection beam 300 includes in-plane deformation detection beam 310 and out-of-plane deformation detection beam 320.The side of in-plane deformation detection beam 310 is formed by doping force-sensitive resistor, and when in-plane deformation detection beam 310 occurs in-plane deformation, the resistance of force-sensitive resistor will change.The surface of out-of-plane deformation detection beam 320 is formed by doping force-sensitive resistor, and when out-of-plane deformation detection beam 320 occurs perpendicular to the plane deformation, the resistance of force-sensitive resistor will change.

[0026] As shown, Figure 2 Multistage buffer stop structure 400 includes 2 fixed beams 410 and 3 movable beams 420, fixed beam 410 and movable beam 420 are staggered distribution, fixed beam 410 is connected with anchor point 500, movable beam 420 is connected with vibrating mass 100, and gap exists between fixed beam 410 and movable beam 420.First fixed beam position 411 is between first movable beam 421 and second movable beam 422, second fixed beam 412 is between second movable beam 422 and third movable beam 423, the gap width between first fixed beam 411 and first movable beam 421, second movable beam 422 is equal, and the gap width between second fixed beam 412 and second movable beam 422, third movable beam 423 is equal.

[0027] When impacted in the x-axis or y-axis direction, the four vibration masses 100 will displace in the opposite direction of the impact force. When the displacement of the vibration masses 100 exceeds the first gap width, the first movable beam 421 (or the second movable beam 422) on the vibration mass 100 will contact and be pressed against the first fixed beam 411, causing elastic deformation of the first movable beam 421 (or the second movable beam 422) and the first fixed beam 411, thereby absorbing the impact energy. When impacted in the x-axis or y-axis direction to a greater extent, causing the displacement of the vibration masses 100 to exceed the first gap width and further exceed the second gap width, while the first movable beam 421 (or the second movable beam 422) and the first fixed beam 411 are elastically deformed, the second movable beam 422 (or the third movable beam 423) on the vibration mass 100 will also contact and be pressed against the second fixed beam 412, causing elastic deformation of the second movable beam 422 (or the third movable beam 423) and the second fixed beam 412, thereby further absorbing the impact energy. By gradually reducing the impact energy in multiple stages, the impact energy can be avoided from being released all at once, thereby avoiding damage and failure of the movable structure or the stop structure.

[0028] As shown in Figure 3 The upper cover plate 600 has four "b" shaped suspension plates 610, and the positions of the four "b" shaped suspension plates 610 correspond to the positions of the four vibration masses 100. The bottom edge of the "b" shaped suspension plate 610 is fixed on the upper cover plate 600, and the other edges are suspended. The "b" shaped suspension plate 610 is provided with a circular elastic protrusion structure 620. The lower cover plate 700 has the same structure as the upper cover plate 600.

[0029] When impacted in the z-axis direction, the four vibration masses 100 will displace in the z-axis direction. When the displacement of the vibration masses 100 exceeds the allowable value, the vibration masses 100 will first contact and be pressed against the circular elastic protrusion structure 620, and the stress will be transmitted to the "b" shaped suspension plate 610, causing elastic deformation of the "b" shaped suspension plate 610, thereby absorbing the impact energy and avoiding damage caused by excessive deformation of the vibration masses 100. The circular elastic protrusion structure 620 can prevent the vibration masses 100 from sticking to the "b" shaped suspension plate 610.

[0030] As shown in Figure 4 The driving beam 200 has a piezoelectric material film on its surface. By applying the same alternating electric signal to the four pairs of driving beams 200 through an external circuit, the driving beams 200 will deform periodically under the action of the inverse piezoelectric effect, thereby driving the four vibration masses 100 to vibrate perpendicular to the direction of the driving beam 200, and the motion patterns of the four vibration masses are the same.

[0031] When the rotation around the positive direction of the x-axis occurs, the motion modes of the two vibration masses 100 on the left and right sides remain unchanged, and the two vibration masses 100 on the upper and lower sides will be deflected vertically to the plane under the action of the Coriolis force. The vibration mass 100 on the upper side deflects to the positive direction of the z-axis, and the vibration mass 100 on the lower side deflects to the negative direction of the z-axis. The deflection of the vibration mass 100 will drive the out-of-plane deformation detection beam 320 connected thereto to deform vertically to the plane, causing the resistance values of the two pairs of force-sensitive resistors on the upper and lower out-of-plane deformation detection beams 320 to change. By detecting the resistance value changes of the force-sensitive resistors on the corresponding out-of-plane deformation detection beam 320 through an external detection circuit, the rotation angular velocity around the x-axis direction can be detected.

[0032] When the rotation around the positive direction of the y-axis occurs, the two vibration masses 100 on the left and right sides will be deflected vertically to the plane under the action of the Coriolis force. The vibration mass 100 on the left deflects to the negative direction of the z-axis, and the vibration mass 100 on the right deflects to the positive direction of the z-axis. The deflection of the vibration mass 100 will drive the out-of-plane deformation detection beam 320 connected thereto to deform vertically to the plane, causing the resistance values of the two out-of-plane deformation detection beams 320 on the left and right sides to change. By detecting the resistance value changes of the force-sensitive resistors on the corresponding out-of-plane deformation detection beam 320 through an external detection circuit, the rotation angular velocity around the y-axis direction can be detected.

[0033] When the rotation around the positive direction of the z-axis occurs, the four vibration masses 100 will all be deflected counterclockwise in the plane under the action of the Coriolis force, driving the in-plane deformation detection beam 310 connected thereto to deform in the plane, causing the resistance values of the force-sensitive resistors on the in-plane deformation detection beam 310 to change. By detecting the resistance value changes of the force-sensitive resistors on the corresponding in-plane deformation detection beam 310 through an external detection circuit, the rotation angular velocity around the z-axis direction can be detected.

[0034] The rotations of the x-axis, y-axis and z-axis will cause the four vibration masses 100 to have different deflection modes, thereby causing the resistance values of the force-sensitive resistors on the three pairs of detection beams 300 connected to the vibration masses 100 to change in different modes. By distinguishing these resistance value change modes, the rotations of the x-axis, y-axis and z-axis can be decoupled.

[0035] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and modifications can be made to these embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An overtorque resistant three-axis MEMS gyroscope, characterized by, The application relates to a micro-electromechanical system (MEMS) accelerometer, which comprises the following components: a vibrating mass, driving beams, detection beams, multi-stage buffer stop structures, anchor points, an upper cover plate and a lower cover plate. The vibrating mass is in orthogonal symmetric distribution, each vibrating mass is connected with one pair of driving beams and three pairs of detection beams, and three pairs of multi-stage buffer stop structures are distributed around each vibrating mass.

2. The over-load resistant tri-axial MEMS gyroscope according to claim 1, wherein, The driving beam side is provided with a piezoelectric material film, the piezoelectric material film drives the driving beam to move vertically to the driving beam direction under the excitation of an external driving circuit.

3. The over-load resistant three-axis MEMS gyroscope of claim 1, wherein, The multi-stage buffer stop structure comprises two fixed beams and three movable beams, the fixed beams and the movable beams are alternately distributed, the first fixed beam is located between the first movable beam and the second movable beam, the second fixed beam is located between the second movable beam and the third movable beam, the gap width between the first fixed beam and the first movable beam and the second movable beam is equal, and the gap width between the second fixed beam and the second movable beam and the third movable beam is equal.

4. The overtorque resistant three-axis MEMS gyroscope of claim 1, wherein, The gap width between the first fixed beam and the first movable beam and the second movable beam of the multi-stage buffer stop structure is smaller than the gap width between the second fixed beam and the second movable beam and the third movable beam.

5. The overtorque resistant three-axis MEMS gyroscope of claim 1, wherein, The detection beam comprises one pair of surface-out motion detection beams and two pairs of surface-in motion detection beams, the surface-out motion detection beam is formed by surface doping to form a surface force sensitive resistor, and the surface-in motion detection beam is formed by side doping to form a side force sensitive resistor.

6. The overtorque resistant three-axis MEMS gyroscope of claim 1, wherein, The upper cover plate and the lower cover plate are provided with flexible stop structures in the areas corresponding to the four vibrating masses, the flexible stop structures are "convex" type suspensions, the bottom edge of each "convex" type suspension is fixed on the cover plate, the remaining edges are suspended, and circular elastic convex point structures are arranged on the "convex" type suspensions.

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