RU152289U1 - MICROELECTROMECHANICAL AXIAL ACCELEROMETER - Google Patents

Abstract

A microelectromechanical axial accelerometer comprising a housing made in the form of a board made of dielectric material, an inertial mass made in the form of a silicon plate located with a gap relative to the housing, elastic jumpers forming an elastic suspension, which ensures the movement of the inertial mass along the first axis lying in the inertial plane mass, capacitive sensor of the output signal, made in the form of four identical sections located symmetrically relative to the center point of the device, connected m Electrically connected and included in a differential circuit, an electronic signal processing circuit and anchors, characterized in that an external rectangular silicon frame is introduced, located with a gap relative to the housing, in the center of each side of which there are rectangular slots, inside of which there are anchors associated with the outer frame with four elastic jumpers that do not allow linear movement of the outer frame along the first and second axes, an inertial mass is placed inside the outer frame, in the center of which A rectangular cut-through slot is introduced, inside of which are placed the first and second identical internal silicon rectangular frames, located symmetrically on both sides of the second axis of the rectangular coordinate system with a beginning in the center of the device, the centers of mass of each of the two internal frames are located on the first axis, inside each from the frames, in their central parts, there are anchors connected to each of the frames with elastic jumpers that do not allow linear movement of each of the frames along the first and second axes, two outwards

Description

The proposed utility model relates to measuring equipment, in particular, to the field of instrumentation, and may find application in inertial navigation systems.

Known microelectromechanical axial accelerometer [Raspopov V.Ya. Micromechanical devices, M., “Mechanical Engineering”, 2007, p. 22, fig. 1.4], comprising a housing, an inertial mass, an elastic suspension, an output signal sensor and anchors.

The features of the analogue coincide with the following features of the proposed utility model. The movable electrodes of the output sensor are placed on an inertial mass.

The disadvantages of the known analogue include low accuracy due to the influence of changes in ambient temperature. In the known analogue, the fixed electrodes of the output signal sensor are located on the housing, and the movable ones on the inertial mass. The body is made of glass. The inertial mass is made of silicon. The coefficients of linear thermal expansion of glass and silicon differ by about one and a half times. A change in ambient temperature leads to undesirable deformations of the elements of the output signal sensor, which lead to a decrease in the accuracy of the device.

The closest in technical essence to the proposed device is a microelectromechanical axial accelerometer [Russia, utility model patent No. 129657, G01P 15/08, publ. June 27, 2013 Byul. No. 18] ,. comprising a housing, an inertial mass, an elastic suspension, a capacitive sensor of the output signal, an electronic signal processing circuit, and reference platforms or anchors.

The features of the closest analogue coincide with the following features of the proposed utility model. The capacitive sensor of the output signal is made in the form of four identical sections located symmetrically relative to the center point of the device. Sections are interconnected electrically and included in a differential circuit. The movable electrodes of the output sensor are placed on an inertial mass. Fixed electrodes - on silicon wafers.

The disadvantages of the closest analogue include low accuracy due to the influence of changes in ambient temperature. Silicon plates on which the fixed electrodes are placed are mounted directly on the device body, i.e. on the glass.

The problem to which the proposed utility model is directed is to reduce the influence of ambient temperature on the operation of the accelerometer and ultimately to increase the accuracy of its operation.

The technical result is obtained due to the fact that in a microelectromechanical axial accelerometer containing a housing made in the form of a board made of a dielectric material, an inertial mass made in the form of a silicon plate located with a gap relative to the housing, elastic jumpers forming an elastic suspension providing for inertial movement mass along the first axis lying in the plane of inertial mass, a capacitive sensor of the output signal, made in the form of four identical sections located symmetrically relative to Along the central point of the device, electrically connected and connected by a differential circuit, an electronic signal processing circuit and anchors, an external rectangular silicon frame is introduced, located with a gap relative to the body, in the center of each side of which rectangular cuts are made, inside which anchors are placed, connected with the outer frame by four elastic jumpers that do not allow linear movement of the outer frame along the first and second axes, the inertia is placed inside the outer frame a mass in the center of which a rectangular slot is made, inside which are placed the first and second identical internal silicon rectangular frames, symmetrically located on both sides of the second axis of the rectangular coordinate system with the origin in the center of the device, the centers of mass of each of the two internal frames are located on the first axis, inside each of the frames, in their central parts, are anchors connected to each of the frames with elastic jumpers that do not allow linear movement of each of the frames along the first of the second and second axes, on two outer sides parallel to the first axis, each frame contains fixed electrodes of the capacitive sensor of the output signal, the movable electrodes of which are placed on two inner sides of the inertial mass parallel to the first axis.

The essential features of the proposed utility model are:

- additional introduction of the outer frame of silicon;

- the location of the inertial mass inside the outer frame;

- additional introduction of the first and second internal frames of silicon;

- the location of the fixed electrodes of the output signal sensor on the internal frames;

- the location of the anchors (bearing pads) and elastic jumpers in such a way as to prevent linear movements of the outer frame and two inner frames along the first and along the second axis.

The specified set of essential features is sufficient to achieve the claimed technical result.

The essence of the proposed utility model is illustrated by graphic images. In FIG. 1 shows a schematic structural diagram of a device. In FIG. 2 presents a structural diagram of a microelectromechanical axial accelerometer. In FIG. Figure 3 shows a fragment of the constructive scheme, its central part, in a different proportion.

The device comprises a housing 1 made in the form of a board made of glass, an inertial mass 2 made in the form of a silicon plate, located with a gap relative to the housing 1 and placed inside the outer rectangular frame 3 of silicon. The frame 3 is located with a gap relative to the housing 1 and has four rectangular slots made in the center of each of the sides. Anchors 4 (anchor pads) are placed inside the slots from the slots. Each of the anchors 4 is connected to the outer frame 3 by four jumpers 5. The jumpers 5 are made so as to prevent linear movement of the outer frame 3 along the first axis X-X and along the second axis Y-Y. An inertial mass 2 is placed inside the outer frame 3, connected with the frame 3 by four elastic jumpers 6, allowing the mass 2 to move along the first axis X-X. In the central part of the inertial mass 2, a through slot of a rectangular shape is made, inside which the first 7 and second 8 identical internal silicon frames are placed, symmetrically located on both sides of the second Y-Y axis. Inside each of the frames 7 and 8, anchors 9 are placed, connected to each of the frames 7 and 8 by elastic jumpers 10, which do not allow linear movement of each of the frames 7 and 8 along the first axis X-X and along the second axis Y-Y. On the outer sides of each of the frames 7 and 8 there are fixed electrodes 11 of the capacitive sensor of the output signal 12. Movable electrodes 13 of the sensor of the output signal 12 are located on the inner sides of the inertial mass 2.

The device operates as follows. Under the action of linear acceleration in the direction of the sensitivity axis X-X, the inertial mass 2 deviates from its initial position. This changes the capacitance between the movable 13 and the stationary 11 electrodes of the capacitive sensor 12 of the output signal. The signal taken from the sensor 12 is fed to the input by an electronic signal processing circuit. The voltage at the output of the electronic circuit is the output signal of the device.

In the process of assembling the device during the formation of supporting pads (anchors), silicon is connected to the glass by electrodiffusion welding by applying an external potential difference and simultaneously heating to temperatures of 200 ° C ... 450 ° C. As a result of the connection, stresses are formed due to the difference in the values of the coefficients of linear thermal expansion of glass and silicon. In the proposed device, the silicon electrodes of the output signal sensor, both movable and stationary, are separated from the body (glass) by intermediate elements (frames) and elastic jumpers. The proposed design of the accelerometer makes it possible to reduce the influence of temperature changes on the output characteristics of the device. As shown by experimental studies, the proposed technical solution allowed to reduce the temperature drift of the main parameters of the device by five times compared with the prototype and thereby increase the accuracy of its operation.

Claims (1)

A microelectromechanical axial accelerometer comprising a housing made in the form of a board made of dielectric material, an inertial mass made in the form of a silicon plate located with a gap relative to the housing, elastic jumpers forming an elastic suspension, which ensures the movement of the inertial mass along the first axis lying in the inertial plane mass, capacitive sensor of the output signal, made in the form of four identical sections located symmetrically relative to the center point of the device, connected m Electrically connected and included in a differential circuit, an electronic signal processing circuit and anchors, characterized in that an external rectangular silicon frame is introduced, located with a gap relative to the housing, in the center of each side of which there are rectangular slots, inside of which there are anchors associated with the outer frame with four elastic jumpers that do not allow linear movement of the outer frame along the first and second axes, an inertial mass is placed inside the outer frame, in the center of which A rectangular cut-through slot is introduced, inside of which are placed the first and second identical internal silicon rectangular frames, located symmetrically on both sides of the second axis of the rectangular coordinate system with a beginning in the center of the device, the centers of mass of each of the two internal frames are located on the first axis, inside each from the frames, in their central parts, there are anchors connected to each of the frames with elastic jumpers that do not allow linear movement of each of the frames along the first and second axes, two outwards The stationary electrodes of the capacitive sensor of the output signal, the movable electrodes of which are placed on two inner sides of the inertial mass parallel to the first axis, are placed on the sides parallel to the first axis.

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