Differential circular torque sensor

Abstract

A differential circular torque sensor disclosed by the present invention comprises a differential circular ring movable piece, a light quantum confinement cavity, a horizontal connecting beam and a probe, the differential circular ring movable piece comprises a fixed cavity carrying block and a differential circular ring movable piece, and the light quantum confinement cavity comprises a fixed cavity wall and a movable cavity wall. The movable cavity wall is carried at the tail end of the differential circular ring movable piece, and the fixed cavity wall is carried at the edge of the right side of the fixed cavity carrying block. And one side of the differential circular ring movable piece is connected with the horizontal connecting beam, and the other side of the differential circular ring movable piece is connected with the probe. And when the probe moves, the differential circular ring movable piece is twisted. The torque sensitivity of the differential circular torque sensor provided by the invention depends on the light quantum confinement cavity, so that the differential circular torque sensor can detect and measure the torque change more accurately, and has the characteristic of high sensitivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of torque measurement, and particularly relates to a differential circular torque sensor. Background Art

[0002] A torque sensor is a precision measuring instrument for measuring various torques, rotational speeds, and mechanical powers. It is widely used in the output torque and power detection of various rotating power equipment such as motors / engines / internal combustion engines, and various equipment / devices such as fans / pumps / gearboxes / torque wrenches, railway locomotives / automobiles / tractors / aircraft / ships / mining machinery, etc. The application prospects of high-sensitivity torque sensor technology and products are even broader. The development process of torque sensors is roughly as follows: strain type, phase difference type, electromagnetic induction type, optical mechanical deformation type, etc.

[0003] With the rapid development of MEMS technology, MEMS torque sensor technology has been born and developed. In recent years, the research and productization of MEMS torque dynamic sensor technology based on MEMS technology have become the key development directions in the international academic and industrial fields. Compared with conventional torque sensors, MEMS torque sensors have many advantages such as small size, light weight, low cost, low power consumption, and good reliability. Among them, using silicon semiconductor materials is one of the important ways to realize high-sensitivity MEMS torque sensors.

[0004] In the field of high-sensitivity MEMS torque sensors, foreign researchers have proposed a new type of photonic crystal "beam splitting" nanocavity structure. The photonic crystal "beam splitting" nanocavity supports high optical quality factor modes, and these resonators are patterned to be used as optical "mirrors". The mirrors can move independently and support mechanical resonance, and their characteristics can be customized by designing their mechanical support structures. The mechanical resonance of the mirrors can also be effectively driven by a coupled torque source. Due to its high sensitivity and precision, the nanobeam cavity torque sensor is very suitable for occasions where precise torque measurement is required and has shown excellent performance in modern industrial applications. The existing torque sensors have complex structures and high operating requirements, so they have poor adaptability. At the same time, due to the complex structure, the sensitivity is low, and the integration with existing equipment during use is low. The existing sensor technology has low anti-noise ability. Since existing high-precision torque sensors all use capacitors as sensitive structures, and capacitors are affected by factors such as temperature, the actual operating environmental conditions are relatively harsh. Summary of the Invention

[0005] The object of the present invention is to solve the above problems and provide a differential circular torque sensor that directly measures torque based on the principle that the distance between the cavity walls in an optical quantum confinement cavity affects the resonant wavelength of light in the cavity.

[0006] To solve the above technical problems, the technical solution of the present invention is: a differential circular torque sensor, including a differential ring movable member, a quantum confinement cavity, a horizontal connecting beam and a probe. The differential ring movable member includes a fixed carrier cavity block and a differential ring movable member. The quantum confinement cavity includes a fixed cavity wall and a movable cavity wall. The movable cavity wall is mounted at the end of the differential ring movable member, and the fixed cavity wall is mounted on the right edge of the fixed carrier cavity block; one side of the differential ring movable member is connected to the horizontal connecting beam, and the other side of the differential ring movable member is connected to the probe; when the probe is displaced, the differential ring movable member will be twisted.

[0007] Preferably, the cross-section of the fixed carrier cavity block is a semi-circular structure with a radius of 1 mm, which is used to carry the fixed cavity wall in the quantum confinement cavity.

[0008] Preferably, the cross-section of the differential ring movable member is a semi-ring structure with a radius of 1 mm and a thickness of 500 nm. Both the fixed carrier cavity block and the differential ring movable member are made of a silicon substrate of silicon and silicon oxide.

[0009] Preferably, the differential ring movable member and the fixed carrier cavity block are fabricated in a 400-nm-thick SiN layer above a 500-μm-thick silicon layer; the fixed carrier cavity block only guides the input and output light, and the movement of the differential ring movable member is induced by physical measurement.

[0010] Preferably, the preparation process of the quantum confinement cavity: on the middle SiO2 layer of the SOI substrate, the SiO2 in the middle region is removed by photolithography technology, and a silicon micromachined oscillator structure is fabricated on the top silicon of the rectangular SOI substrate by micro-nano processing technology, while the bottom silicon remains unchanged.

[0011] Preferably, the length of the probe is 1.5 mm, and the length of the horizontal connecting beam is 1 mm. When torque is applied to the probe, the displacement of the probe will cause the differential ring movable member to be twisted.

[0012] Preferably, when the differential ring movable member rotates, the air gap between the fixed cavity wall and the movable cavity wall changes, and the initial size of the air gap is 100 nm.

[0013] Preferably, the number of the fixed cavity wall and the movable cavity wall is two, and they are symmetrically distributed on the differential ring movable member and the fixed carrier cavity block. When there is an external torque, the deflection of the differential ring movable member causes the cavity wall gap between one pair of movable cavity walls and the fixed cavity wall to decrease, then the cavity wall gap between the other pair of movable cavity walls and the fixed cavity wall will increase, and the change amount of the cavity wall gap is the same, forming a differential structure.

[0014] The beneficial effects of the present invention are:

[0015] 1. The torque sensitivity of a differential circular torque sensor provided by the present invention depends on a quantum light confinement cavity. Therefore, it can detect and measure torque changes more accurately and has the characteristic of high sensitivity.

[0016] 2. Compared with traditional torque sensors, the sensor volume of this differential circular torque sensor is greatly reduced, and it has better adaptability in various micro-robot fields.

[0017] 3. Since the two pairs of quantum light confinement cavities are symmetric in structure and form a differential structure, the sensitivity of the sensor is doubled.

[0018] 4. The circular design of the present invention makes the sensor easier to integrate with various devices and systems, whether it is a robotic arm, a motor or other rotating devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a front view structural schematic diagram of a differential circular torque sensor of the present invention;

[0020] Figure 2 is a top view structural schematic diagram of the present invention;

[0021] Figure 3 is a top view when the present invention senses torque;

[0022] Figure 4 is a quantum light confinement cavity diagram of the present invention.

[0023] Description of reference numerals: a, fixed carrier cavity block; b, differential circular movable part; c, horizontal connecting beam; d, probe; e, fixed cavity wall; f, movable cavity wall. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following further describes the present invention with reference to the drawings and specific embodiments:

[0025] As Figures 1 to 4 shown, a differential circular torque sensor provided by the present invention includes a differential circular movable part, a quantum light confinement cavity, a horizontal connecting beam c and a probe d. The differential circular movable part includes a fixed carrier cavity block a and a differential circular movable part b. The quantum light confinement cavity includes a fixed cavity wall e and a movable cavity wall f. The movable cavity wall f is mounted at the end of the differential circular movable part b, and the fixed cavity wall e is mounted on the right edge of the fixed carrier cavity block a. One side of the differential circular movable part b is connected to the horizontal connecting beam c, and the other side of the differential circular movable part b is connected to the probe d. When the probe d is displaced, the differential circular movable part b will be twisted.

[0026] The cross-section of the fixed cavity carrier block a is a semi-circular structure with a radius of 1 mm, which is used to carry the fixed cavity wall e in the optical quantum confinement cavity.

[0027] The cross-section of the differential ring movable part b is a semi-circular ring structure with a radius of 1 mm and a thickness of 500 nm. Both the fixed cavity carrier block a and the differential ring movable part b are made of a silicon substrate of silicon and silicon dioxide. The differential ring movable part b will deflect accordingly according to the magnitude of the external torque.

[0028] The differential ring movable part b and the fixed cavity carrier block a are fabricated in a 400-nm-thick SiN layer above a 500-μm-thick silicon layer; the fixed cavity carrier block a only guides the input and output light, and the movement of the differential ring movable part b is induced by physical measurement.

[0029] The preparation process of the optical quantum confinement cavity: By removing the SiO2 in the middle region through photolithography technology on the middle SiO2 layer of the SOI substrate, a silicon micromachined oscillator structure is fabricated on the top silicon of the rectangular SOI substrate through micro-nano processing technology, while the bottom silicon remains unchanged.

[0030] The length of the probe d is 1.5 mm, the beam length of the horizontal connecting beam c is 1 mm, and the width is 0.2 mm. When a torque is applied to the probe d, the displacement of the probe d will cause the differential ring movable part b to twist. The probe d is used to sense the external torque source.

[0031] In this embodiment, the end of the horizontal connecting beam c is fixedly connected to the fixed cavity carrier block, and the other end of the horizontal connecting beam c abuts against the middle of the differential ring movable part b. When a downward force is applied to the right side of the probe d, the differential ring movable part b rotates around the end of the horizontal connecting beam c.

[0032] When the differential ring movable part b rotates, the air gap between the fixed cavity wall e and the movable cavity wall f changes, and the initial size of the air gap is 100 nm.

[0033] The number of both the fixed cavity wall e and the movable cavity wall f is two, and they are symmetrically distributed on the differential ring movable part b and the fixed cavity carrier block a. When there is an external torque, the deflection of the differential ring movable part b causes the cavity wall gap between one pair of movable cavity walls f and the fixed cavity wall e to decrease, while the cavity wall gap between the other pair of movable cavity walls f and the fixed cavity wall e will increase, and the change amount of the cavity wall gap is the same, forming a differential structure.

[0034] When there is an external torque, the probe d deflects, driving the differential circular movable part b to rotate, causing one end of the end of the differential circular movable part b to move leftward and the other end to move rightward. The movable cavity wall f of the optical quantum confinement cavity is carried at its end. Therefore, a horizontal displacement relative to the fixed cavity wall e occurs, causing the air gap between the movable cavity wall and the fixed cavity wall in the optical quantum confinement cavity to change. This causes the resonant wavelength of the laser in the cavity wall gap to change.

[0035] As Figure 4 shown, the holes f1 in the photonic crystal are arranged in a regular hexagonal honeycomb pattern such as f3 to form a photonic crystal microcavity, and f2 is the cavity air groove gap. The measurement process of a differential circular torque sensor of the present invention is analyzed as follows:

[0036] The fixed carrier cavity block only guides the input and output light, and the movement of the differential circular movable part b can be induced by various physical quantities. The physical quantity in this embodiment refers to the physical power provided by an external device, such as torque, etc. The resonant wavelength of the laser in the optical quantum confinement cavity above it is affected by the mechanical movement of the movable part. In the optical quantum confinement cavity, when the movable cavity wall f and the fixed cavity wall e are in the original state, the distance between the cavity walls is 100 nm. The relationship between the cavity wall gap of the optical quantum confinement cavity and the resonant wavelength of the laser inside it is:

[0037] m*λ=2n c L.

[0038] Where λ is the resonant wavelength, nc is the effective refractive index, and L is the cavity wall gap of the optical quantum confinement cavity. Specifically, in the static state of the present invention, the air groove gap is 100 nm. When there is a torque T and the differential circular movable part b deflects, one end will move x nanometers away from the fixed carrier cavity block, and the other end will move x nanometers closer to the fixed carrier cavity block. Then the air groove gaps will become (100 - x) and (100 + x) respectively. Since the relationship between the laser wavelength and the air groove gap is m*λ=2n c L, the corresponding wavelengths are 2n c (100 + x) / m and 2n c (100 - x) / m. Among them, the wavelength λ and the air groove gap L are linearly related, and the laser wavelength will also change. The laser of the present invention is input from an optical fiber of an external prior art device. After resonance, its wavelength is linearly related to the air groove gap.

[0039] When there is an external torque, the probe d deflects, driving the differential ring movable part b to rotate, causing one end of the differential ring movable part b to move leftward and the other end to move rightward. The movable cavity wall f of the optical quantum confinement cavity is carried at its end. Therefore, a horizontal displacement relative to the fixed cavity wall e occurs, causing the air gap between the movable cavity wall and the fixed cavity wall in the optical quantum confinement cavity to change, thus affecting the resonance wavelength of the laser in the optical quantum confinement cavity. Since the wavelength change has a linear relationship with the displacement change, and the displacement change has a linear relationship with the external torque, the corresponding torque magnitude can be measured by measuring the corresponding wavelength change.

[0040] In this sensor, two pairs of optical quantum confinement cavities are symmetrically distributed on the differential ring movable part b and the fixed carrier cavity block a. When there is an external torque, the deflection of the differential ring movable part b causes the cavity wall gap between the movable cavity wall and the fixed cavity wall of one pair of optical quantum confinement cavities to decrease, while the cavity wall gap between the movable cavity wall and the fixed cavity wall of the other pair of optical quantum confinement cavities will increase, and the change amounts of the cavity wall gaps of the two pairs of quantum confinement cavities are the same. Therefore, by detecting the change amount, the sensitivity of the sensor can be improved.

[0041] For a differential circular torque sensor of the present invention, when the probe senses an external torque, it will cause the differential ring movable part to deflect clockwise or counterclockwise, and its deflection causes a nearly horizontal displacement in the optical quantum confinement cavity at the end of the differential ring movable part. This displacement causes the gap between the movable cavity wall and the fixed cavity wall in the optical quantum confinement cavity to change, thus affecting the resonance wavelength of the laser in the optical quantum confinement cavity. Since the wavelength change has a linear relationship with the displacement change, and the displacement change has a linear relationship with the external torque, the corresponding torque magnitude can be measured by measuring the corresponding wavelength change.

[0042] Those of ordinary skill in the art will realize that the embodiments described herein are for helping readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations without departing from the essence of the present invention based on the technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the present invention.

Claims

1. A differential circular torque sensor, characterized in that: The invention comprises a differential circular ring movable part, a photon confinement cavity, a horizontal connecting beam (c) and a probe (d), wherein the differential circular ring movable part comprises a fixed cavity block (a) and a differential circular ring movable part (b), and the photon confinement cavity comprises a fixed cavity wall (e) and a movable cavity wall (f), wherein the movable cavity wall (f) is mounted on the end of the differential circular ring movable part (b), and the fixed cavity wall (e) is mounted on the right edge of the fixed cavity block (a); one side of the differential circular ring movable part (b) is connected to the horizontal connecting beam (c), and the other side of the differential circular ring movable part (b) is connected to the probe (d); when the probe (d) is displaced, the differential circular ring movable part (b) will be twisted.

2. A differential circular torque sensor according to claim 1, characterized in that: The cross section of the fixed cavity block (a) is a semicircular structure with a radius of 1 mm, and is used to carry the fixed cavity wall (e) in the photon confinement cavity.

3. A differential circular torque sensor according to claim 1, characterized in that: The cross section of the differential circular ring movable part (b) is a semicircular ring structure with a radius of 1 mm and a thickness of 500 nm. The fixed cavity block (a) and the differential circular ring movable part (b) are both made of silicon substrates of silicon and silicon oxide.

4. A differential circular torque sensor according to claim 1, characterized in that: The differential annular movable element (b) and the fixed cavity block (a) are fabricated in a 400 nm thick SiN layer above a 500 μm silicon layer; the fixed cavity block (a) only guides input and output light, and the movement of the differential annular movable element (b) is induced by physical measurement.

5. The differential circular torque sensor according to claim 1, characterized in that: The preparation process of the optical quantum confinement cavity is as follows: on the middle SiO2 layer of the SOI substrate, the SiO2 in the middle area is removed by photolithography technology, and a silicon micromechanical oscillator structure is made on the top silicon of the rectangular SOI substrate by micro-nano processing technology, while the bottom silicon remains unchanged.

6. A differential circular torque sensor according to claim 1, characterized in that: The probe (d) is 1.5 mm long, and the horizontal connecting beam (c) is 1 mm long. When torque is applied to the probe (d), the displacement of the probe (d) will cause the differential circular movable part (b) to twist.

7. The differential circular torque sensor according to claim 1, characterized in that: When the differential annular movable element (b) rotates, the air gap between the fixed cavity wall (e) and the movable cavity wall (f) changes, and the initial size of the air gap is 100 nm.

8. The differential circular torque sensor according to claim 1, characterized in that: The number of the fixed cavity walls (e) and the movable cavity walls (f) are both two, and they are symmetrically distributed on the differential circular ring movable part (b) and the fixed cavity block (a). When there is an external torque, the deflection of the differential circular ring movable part (b) causes the cavity wall gap between one pair of movable cavity walls (f) and the fixed cavity wall (e) to decrease, while the cavity wall gap between the other pair of movable cavity walls (f) and the fixed cavity wall (e) will increase, and the change in the cavity wall gap is consistent, forming a differential structure.

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