CN100403001C - Differential piezoelectric three-dimensional force sensor - Google Patents

Abstract

A differential piezoelectric three-dimensional force sensor. The sensor includes a load cell composed of a quartz wafer and a fixed insulating positioning frame, a base with a signal lead-out socket and a cover of the base. Wherein the insulation positioning frame is provided with eight positioning holes, and the center line of each positioning hole is a square. Four positioning holes are at the four corners of the square, and the quartz wafers in the four corners are all X0° cut quartz crystals, their X axes are all perpendicular to the square, and the axial directions of adjacent corner wafers are opposite; the other four positioning holes are in the The midpoints of the four sides of the square and the quartz wafers in the midpoint positioning holes are all Y0° cut quartz crystals, their X axes are all parallel to the respective corresponding sides, and the axial directions of the opposite side wafers are opposite. The invention is simple in structure, easy to process and manufacture, and can realize differential measurement of force signals; has high measurement accuracy, can overcome the errors caused by changes in the environment (such as temperature and humidity), and is suitable for various occasions Measurement of three-dimensional forces in space.

Description

Differential piezoelectric three-dimensional force sensor

technical field

The invention relates to a sensor for measuring three-dimensional force in space.

Background technique

At present, the known piezoelectric three-dimensional force sensor is composed of a base, a cover, a quartz wafer, an electrode, an insulating positioning member, a signal lead-out socket and the like. As shown in Figures 1 to 5, the piezoelectric three-dimensional force sensor is installed in the base after combining three quartz wafers in such a way that the maximum sensitivity axes form a 90° angle with each other, and then the cover and the base welded together. When a spatial force acts on the sensor, the magnitude of the three-dimensional force in space is reflected by detecting the charge output of three quartz wafers. However, this piezoelectric three-dimensional force sensor not only has a weak output signal when the external force is small, but the measurement accuracy is not high, and at the same time, it cannot overcome the error caused by the change of the environment (such as temperature and humidity).

Contents of the invention

The technology to be solved by the present invention is to overcome the deficiencies of the existing piezoelectric three-dimensional force sensor, and propose a method that not only has a strong output signal and high measurement accuracy when the external force is small, but can also overcome the environmental (such as temperature, humidity) The variation of the piezoelectric three-dimensional force sensor brings errors to the measurement.

The technical solution adopted to solve the technical problem of the present invention is a differential piezoelectric three-dimensional force sensor. It is the same as the prior art in that the sensor includes a dynamometer consisting of a quartz wafer with a signal output electrode and an insulating spacer for fixing the quartz wafer, and a dynamometer that encapsulates the dynamometer in it. The inner cavity has a base of a signal lead-out socket, and a cover pre-pressed on the quartz wafer and sealing the base. The quartz wafer with the signal output electrodes is the so-called piezoelectric element. The improvement of the present invention is that the insulating positioning frame is provided with eight positioning holes, and the center line of each positioning hole is a square. The four positioning holes are at the four corners of the square, and the quartz wafers positioned in the four corner positioning holes are all X0° cut quartz crystals. The X axes of these four wafers are all perpendicular to the square, and the axial directions of adjacent corner wafers are opposite. ; The other four positioning holes are at the midpoints of the four sides of the square, and the quartz wafers positioned in the midpoint positioning holes of the four sides are all Y0° cut-type quartz crystals, and the X axes of these four wafers are all parallel to respective corresponding sides, and The axial directions of the wafers on opposite sides are opposite.

When the three-dimensional space force acts on the sensor of the present invention, the upper surfaces of the two pairs of X0 ° cut-type quartz crystal sheets positioned in two groups of diagonal positioning holes will respectively produce positive and negative charge changes; The upper surfaces of the two pairs of Y0°-cut quartz crystal sheets in the midpoint positioning holes of the two groups of opposite sides will also generate positive and negative charge changes respectively. The differential measurement of the spatial three-dimensional force signal can be realized by means of the differential charge amplifier.

The beneficial effects of the present invention are that the differential piezoelectric three-dimensional force sensor has no force coupling, is simple in structure, is easy to process and manufacture, and can realize differential measurement of force signals; Hours, the output signal is strong and the measurement accuracy is high; it can overcome the error caused by changes in the environment (such as temperature and humidity), and is suitable for the measurement of three-dimensional forces in space in various occasions.

The present invention will be further described below in conjunction with the accompanying drawings.

Description of drawings

Fig. 1 is a structural diagram of an existing piezoelectric three-dimensional force sensor;

Fig. 2 is a top view of Fig. 1;

Fig. 3, Fig. 4 and Fig. 5 are three quartz wafers whose maximum sensitivity among Fig. 1 forms an angle of 90°;

Fig. 6 is the front view of the dynamometer in the present invention;

FIG. 7 is a top view of FIG. 6 .

Fig. 8 is the front view of the present invention;

FIG. 9 is a top view of FIG. 8 .

Detailed ways

Differential piezoelectric three-dimensional force sensor (refer to Figures 6, 7, 8, and 9). Same as the prior art, the sensor includes a dynamometer composed of a quartz wafer with a signal output electrode and an insulating positioning frame for fixing the quartz wafer, with an inner cavity in which the dynamometer is packaged and a There is a base with a signal lead-out socket, and a cover that is pre-pressed on the quartz wafer and covers the base. Wherein, the signal output electrodes of the quartz wafer are connected with the signal lead-out sockets 12 on the base in one-to-one correspondence, and then directly connected with the differential charge amplifier by a commercially available connection line with a Teflon connector. The present invention is characterized in that the insulating positioning frame is provided with eight positioning holes, and the connecting lines between the centers of the positioning holes are square. Four positioning holes in them are at the four corners of this square, and the quartz wafers (1, 3, 5, 7) positioned in the four corners of the positioning holes are all X0 ° cut quartz crystals, and these four wafers (1, 3, 5 , 7) the X axes are all perpendicular to the square, and the axial directions of the adjacent corner wafers are opposite—obviously, the axial directions of the diagonal wafers (1, 5 and 3, 7) are the same; the other four positioning holes At the midpoint of the four sides of the square, the quartz wafers (2, 4, 6, 8) positioned in the four-side midpoint positioning holes are all Y0 ° cut quartz crystals, and these four wafers (2, 4, 6, 8) The X-axes of the wafers are all parallel to the respective corresponding sides, and the axial directions of the opposite side wafers are opposite. That is to say, the centers of 8 quartz wafers are on the central ring line of the whole square ring; The maximum sensitivity axes of the quartz wafers (1, 3, 5, 7) in the positioning holes at the four corners form an angle of 90° with each other in the measurement space. Wherein, one group of quartz wafers (2,6) in the midpoint positioning holes of opposite sides measure the force in the X (or Y) direction, and another group of quartz wafers (4,8) in the midpoint positioning holes of opposite sides measure Y ( Or the force in the X) direction, and the quartz wafer (1, 3, 5, 7) in the four corner positioning holes measure the force in the Z direction. When connecting with a differential charge amplifier, connect the output charge signals of a group of quartz wafers (2, 6) positioned in the positioning holes at the midpoint of opposite sides of the square to the two input terminals of the differential charge amplifier to obtain X (or Y, because X, Y direction formula can be interchanged) the size of axial force; Another group is positioned at the output electric charge signal of the quartz wafer (4,8) in the midpoint positioning hole of the opposite side of the square The two input terminals of the differential charge amplifier can obtain the magnitude of the Y (or X) axial force; the output charge signal after the parallel connection of the quartz wafers (1, 5) positioned in a group of diagonal positioning holes of the square After connecting to one input terminal of the differential charge amplifier, connect the parallel output charge signal of the quartz wafers (3, 7) positioned in another set of diagonal positioning holes of the square to the other input of the differential charge amplifier end, the magnitude of the Z-axis force can be obtained.

In order to ensure that the X-axis of each wafer can be accurately positioned according to their respective directions. Further feature is (with reference to Fig. 6,7), eight positioning holes and the quartz wafer (1,2,3,4,5,6,7,8) in the positioning holes thereof are all squares of equal size, these eight The square sides of each positioning hole are all parallel to each corresponding side of the square connected to the center.

In order to further ensure the assembly quality of the present invention. A further feature is (with reference to Fig. 7), the insulating spacer 9 is a square ring frame, the center of the inner and outer squares of the insulating spacer 9 coincides with the center of the square of the above-mentioned center connection line, and the corresponding sides of the three squares are all connected to each other. parallel.

Further feature is again (referring to Fig. 8,9), base 11 is made into a square box, and lid 10 is made into the plug type lid that two centerlines coincide and each corresponding side is made of parallel square blocks. The inner cavity of the base 11 is matched with the square shape of the insulating spacer packaged therein and the four sides of the large square block of the cover 10 thereof, and the middle part of the inner cavity of the base 11 has four sides of the small square block of the cover 10 A groove that matches and is smaller than the square hole of the insulation spacer. The base 11 and the cover 10 also have a sensor clamping hole 13 penetrating them simultaneously, and the center line of the sensor clamping hole 13 coincides with the center line of the square block.

The product manufacturing process of the best effect of the present invention is briefly described as follows: first at the center of the square insulating material, process a square hole; Then, process 8 and quartz wafers (1,2,3,4, 5, 6, 7, 8) matched square holes, the insulating positioning frame of the sensor is obtained, and then, 8 quartz wafers (1, 2, 3, 4, 5, 6 , 7, 8) are installed in the insulating positioning frame to constitute the dynamometer of the differential piezoelectric three-dimensional force sensor. Then, process an inner cavity (this inner cavity will be slightly wider than the dynamometer) on the square base 11 to place the dynamometer, according to the shape of its inner cavity, it is equipped as a cover 10. Finally, install the dynamometer in the base 11 vertically and symmetrically, cover the cover 10, and then use electron beam welding technology to weld the base 11 and the cover 10 together to form the differential piezoelectric three-dimensional force sensor .

Claims (4)

1. Differential piezoelectric three-dimensional force sensor, the sensor includes a dynamometer composed of a quartz wafer with a signal output electrode and an insulating positioning frame for fixing the quartz wafer, with the dynamometer packaged in it The inner cavity of the inner cavity has a base of a signal lead-out socket, and a cover that is pre-pressed on the quartz wafer and covers the base. It is characterized in that the insulating positioning frame (9) has eight positioning holes, and each positioning The central line of the hole is a square; four positioning holes are at the four corners of the square, and the quartz wafers (1, 3, 5, 7) positioned in the four corners of the positioning holes are all X0 ° cut quartz crystals, and these four wafers ( 1, 3, 5, 7) the X-axis is perpendicular to the square, and the axial direction of the adjacent corner wafer is opposite; the other four positioning holes are at the midpoint of the four sides of the square, and the quartz in the four-side midpoint positioning hole is positioned The wafers (2, 4, 6, 8) are all Y0° cut quartz crystals, and the X axes of these four wafers (2, 4, 6, 8) are all parallel to the corresponding sides and the axial direction of the opposite side wafers. on the contrary. 2. differential piezoelectric three-dimensional force sensor according to claim 1, is characterized in that, described eight positioning holes and the quartz wafers (1, 2, 3, 4, 5, 6) in the positioning holes thereof , 7, 8) are all squares of equal size, and the square sides of these eight positioning holes are all parallel to each corresponding side of the square of the described center line. 3. The differential piezoelectric three-dimensional force sensor according to claim 2, characterized in that, the insulating spacer (9) is a square ring frame, and the center of the inner and outer squares of the insulating spacer (9) is in line with the The centers of the squares connected by the center line coincide, and the corresponding sides of the three squares are all parallel to each other. 4. The differential piezoelectric three-dimensional force sensor according to claim 3, characterized in that, the base (11) is a square box, and the cover (10) is coincident with two centerlines of a large and small size, and each A plug-type cover formed by square blocks whose corresponding sides are parallel to each other; the inner cavity of the base (11) matches the square shape of the insulating spacer (9) and the four sides of the large square block of the cover (10), The middle part of this pedestal (11) inner chamber has the four sides matching of the small square block of its cover (10), and is smaller than the groove of the square hole of described insulating spacer (9); This pedestal (11) and cover ( 10) There are sensor clamping holes (13) penetrating them simultaneously, and the center line of the sensor clamping hole (13) coincides with the center line of the square block.

Images