A method for detecting a curved micro gap or curvature, a sensing device and an experimental device

Abstract

The application provides a detection method for a curved micro gap or curvature, a sensing device and an experimental device. The detection method comprises a sensitive element, packaging of the sensitive element, a signal processing circuit and the like. On the premise that the sensitive element and a conductor are coaxial, when the distance (i.e. the gap thickness) between the sensitive element and the axis of the conductor or the curvature of the conductor changes, the strength of the eddy current generated on the surface of the conductor changes, which leads to the change of the impedance of the sensitive element and further leads to the change of the output voltage of the signal processing circuit. When the curvature of the conductor is constant, based on the monotonic mapping relationship between the output voltage and the gap thickness, the gap thickness information can be obtained; when the gap thickness is constant, based on the monotonic mapping relationship between the output voltage and the curvature of the conductor, the curvature information of the conductor can be obtained. Facing the working conditions such as lubrication state detection of a rolling bearing, the non-invasive and non-destructive measurement of the micro gap thickness or the curvature of the conductor can be realized without interfering with the running state of the device.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, and particularly relates to a method, sensing device and experimental apparatus for detecting minute gaps or curvatures on curved surfaces. Background Technology

[0002] In the fields of mechanical transmission and thermal protection technology, online detection of minute gap thickness and precise measurement of conductor curvature are of significant engineering importance. In rolling bearings, the minute gap thickness between the rolling elements and the outer ring of the bearing can indirectly characterize the thickness of the lubricating oil film, which directly determines the lubrication state and service life of the bearing. The radius of curvature of the rolling elements (such as balls and rollers) is a key geometric parameter affecting contact stress and elastohydrodynamic lubrication characteristics. In aero-engine nozzles and combustion chambers, the thickness distribution of the coolant film on the wall determines the thermal protection effect and the uniformity of wall temperature. In other operating conditions where curved liquid film flow exists, the liquid film thickness and substrate curvature are also key parameters that need to be obtained.

[0003] However, existing methods for detecting the thickness and curvature of minute gaps have limitations when facing complex working conditions and online measurement requirements. Contact measurement methods are prone to scratching surfaces and cannot be used for online detection; optical or acoustic measurement methods have stringent requirements on the stability of the measured working conditions and the characteristics of the medium. Eddy current method, as a non-invasive measurement method, can perform non-contact and non-destructive measurements under measurement conditions that require ensuring the stable operation of the device itself. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a method, sensing device, and experimental apparatus for detecting minute gaps or curvatures on curved surfaces. This method can measure minute gaps or curvatures on curved surfaces without altering the device's operating state and can be applied to scenarios such as measuring the thickness of bearing lubricating oil films and measuring the coolant film on the nozzle and combustion chamber walls of aero-engines.

[0005] A method for detecting minute gaps or curvature on curved surfaces involves setting a sensitive element and a conductor to be coaxial before detection. When the distance between the sensitive element and the conductor axis, i.e., the gap thickness or the curvature of the conductor, changes, the intensity of the eddy currents generated on the surface of the conductor changes, causing a change in the impedance of the sensitive element, which in turn causes a change in the output voltage of the signal processing circuit.

[0006] Furthermore, a method for detecting minute gaps or curvature on a curved surface includes the following steps: When the curvature of a conductor surface is constant, the output voltage of the signal processing circuit corresponding to the current gap thickness is measured. Based on the monotonic mapping relationship between the output voltage and the gap thickness, the gap thickness information is obtained. With a fixed gap thickness between the sensitive element and the conductor, the output voltage of the signal processing circuit corresponding to the current curvature of the conductor is measured. Based on the monotonic mapping relationship between the output voltage and the curvature, the curvature information of the conductor is obtained.

[0007] Furthermore, when the curvature of the conductor remains constant, the impedance of the sensing element changes as the gap thickness changes, which in turn causes the output voltage of the signal processing circuit to change. At the same time, the output voltage when the gap thickness is 0 is taken as the zero-point voltage of the sensing device. When the gap thickness remains constant, the impedance of the sensing element changes with the curvature of the conductor, which in turn causes the output voltage of the signal processing circuit to change. Meanwhile, the output voltage when the radius of curvature is infinite, i.e., when it is a plane, is taken as the zero-point voltage of the sensing device.

[0008] Furthermore, a sensing device for a curved surface with minute gaps or curvature includes a sensing element, a package, and a signal processing circuit; the sensing element is used to acquire information about the thickness or curvature of the minute gap between the conductor and the sensing element; the signal processing circuit is used to acquire information about the thickness or curvature of the minute gap between the conductor and the sensing element based on the impedance information of the sensing element. Among them, when the measurement conditions are bearing oil film thickness or bearing rolling element curvature, when the conductor is the bearing rolling element and the outer ring of the bearing is the stator and the inner ring is the rotor, the sensitive element and its package are integrated into the inner track of the outer ring of the bearing. When the conductor is the rolling element of the bearing and the outer ring of the bearing is the rotor and the inner ring is the stator, the sensitive element and its package are integrated into the inner ring of the bearing.

[0009] Furthermore, the shape of the package matches the inner track of the bearing outer ring or the outer shape of the bearing inner ring; the sensitive element is an eddy current detection coil, and the package is made of non-conductive material.

[0010] Furthermore, an experimental device for a curved surface with minute gaps or curvature is provided, wherein the sensing device, a conductive connector, a liquid seal, a liquid reservoir, and a sensor fixture together constitute the experimental device. The sensing device includes a sensitive element, a top cover, an inner core, a outer shell, and a signal processing circuit. The sensitive element is positioned at the top of the inner core and is placed together with the inner core within a packaged cavity formed by the nested top cover and outer shell. The signal processing circuit is located outside the packaged cavity. The upper end of the liquid seal forms an open cavity, and after one end of the conductor is fixed to the conductor connector, the other end is placed into the open cavity and forms a transition fit with the inner wall of the open cavity, so that a sealed liquid cavity is formed between the conductor and the bottom of the open cavity; the liquid storage tank is installed on the side of the liquid seal and communicates with the liquid cavity; the top of the top cover is connected to the bottom of the liquid seal by a thread; the sensing device is fixedly installed on the sensor fixture by the top cover.

[0011] Furthermore, the conductive connector is fixedly connected to an external stepper axis, which is used to adjust the distance between the top of the conductive body embedded in the open cavity and the top cover under the drive of the external stepper axis; in addition, the conductive connector is also connected to an external digital display micrometer, which is used to control and display the distance between the top of the conductive body embedded in the open cavity and the top cover through the external digital display micrometer.

[0012] Furthermore, when performing curvature detection on the surface of a conductor, it is only necessary to set the sensitive element to be coaxial with the conductor. Under the condition of a certain gap thickness, the curvature of the surface of the conductor can be measured without the need for liquid seals and oil tanks.

[0013] Furthermore, the liquid storage tank is used to release a liquid medium into the liquid cavity, so that the end of the conductor placed into the open cavity is covered with a liquid film.

[0014] Furthermore, the inner core, the bottom of the outer shell, and the inside of the sensor fixture are all provided with lead-out channels for connecting the lead wires of the sensitive element to the signal processing circuit.

[0015] Beneficial effects: 1. This invention provides a method for detecting minute gaps and curvature of curved surfaces. By utilizing the characteristic that the output impedance of a sensitive element changes monotonically with the distance between the sensitive element and the conductor or the radius of curvature of the conductor, the method can detect minute gaps or curvature of curved surfaces.

[0016] 2. This invention provides a sensing device and experimental apparatus for detecting minute gaps or curvature of curved surfaces. Under conditions such as detecting the thickness of lubricating oil film or the curvature of rolling elements in rolling bearings, and detecting the thickness of coolant film on the walls of aero-engine nozzles and combustion chambers, it can detect minute gaps or curvature of curved surfaces without damaging the measured surface and the state of the liquid film. Attached Figure Description

[0017] Figure 1 The working principle diagram of the sensing device provided by the present invention; Figure 2 An exploded view of the experimental apparatus provided by the present invention; Figure 3 An assembly diagram of the experimental apparatus provided by the present invention; Figure 4 This is a design diagram of a sensing device for measuring the oil film thickness of a space bearing, provided by the present invention. Figure 5 A schematic diagram of the installation space of the inner track when the sensing device provided by the present invention is integrated into the inner track of the outer ring of the bearing; Figure 6 This is a schematic diagram showing the relative position of the sensing device and the conductor when the sensing device provided by this invention is integrated into the inner track of the outer ring of the bearing. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0019] This invention provides a method, sensing device, and experimental apparatus for detecting minute gaps or curvatures on curved surfaces. By utilizing the characteristic that the output impedance of the sensing element changes monotonically with the distance between the sensing element and the conductor or the radius of curvature of the conductor, the detection of minute gaps or curvatures on curved surfaces can be achieved.

[0020] Figure 1 A schematic diagram illustrating the working principle of the sensing device provided by this invention is shown. Before detection, the sensitive element and the conductor should be set to be coaxial. When the distance (i.e., gap thickness) between the sensitive element and the conductor axis or the curvature of the conductor changes, the intensity of the eddy currents generated on the surface of the conductor changes, causing a change in the impedance of the sensitive element, which in turn causes a change in the output voltage of the signal processing circuit.

[0021] When the curvature of a conductor surface is constant, as the distance (i.e., gap thickness) between the conductor and the sensing element changes, the impedance of the sensing element changes, which in turn leads to a change in the output voltage of the signal processing circuit. When the gap thickness (i.e., the relative distance along the axis of the sensing element) between the sensing element and the conductor is constant, as the curvature of the conductor changes, the impedance of the sensing element changes, which in turn leads to a change in the output voltage of the signal processing circuit.

[0022] Therefore, under the condition of keeping a single variable constant, the output impedance of the sensing element can reflect the distance (i.e., gap thickness) or curvature information between the measured conductor and the sensing element, thus providing a theoretical basis for the sensing device to detect minute gap thickness or conductor curvature. In other words, this invention encapsulates the sensing element inside a cavity, enabling the detection of another parameter while keeping the conductor curvature or gap thickness constant. Figure 2 and Figure 3 As shown, the sensing device of the present invention, together with the conductive connector, the liquid seal, the liquid storage tank and the sensor fixing component, constitutes an experimental device. The sensing device includes a sensitive element, a signal processing circuit and a top cover, an inner core and a shell, all made of non-conductive materials. Optionally, the sensitive element is an eddy current detection coil. The upper end of the liquid seal forms an open cavity. One end of the conductor is fixed to the conductor connector, and the other end is inserted into the open cavity, forming a transition fit with the inner wall of the open cavity, thus forming a sealed liquid cavity between the conductor and the bottom of the open cavity. The liquid reservoir is installed on the side of the liquid seal and communicates with the liquid cavity, used to release the liquid medium into the liquid cavity, so that the end of the conductor inserted into the open cavity is covered with the liquid film to be measured. The sensing element is arranged at the top of the inner core and is placed together with the inner core in an encapsulated cavity formed by the nested upper cover and outer shell. The signal processing circuit is located outside the encapsulated cavity. The top of the upper cover is threaded to the bottom of the liquid seal. The sensing device is fixedly mounted on the sensor fixture via the upper cover. Lead-out channels for connecting the sensitive element's lead wires to the signal processing circuit are provided in the middle of the inner core, the bottom of the outer shell, and inside the sensor fixture.

[0023] As can be seen, the conductor of the present invention is located at the top of the sensing device, and its surface is covered with a liquid film; the sensing device is located below the conductor and directly contacts the surface of the liquid film; the sensitive element is encapsulated inside the sensing device and does not directly contact the liquid film to avoid liquid contamination of the sensitive element; the liquid seal and the matching liquid storage tank can control the liquid to fill the space between the conductor and the sensing device and achieve the sealing of the liquid film; the sensor fixing component is located at the bottom of the experimental device and is used for the overall installation and positioning of the experimental device. The entire experimental device can ensure the continuity and controllability of the liquid film.

[0024] It should be noted that the conductive connector is fixedly connected to an external stepper axis, used to adjust the distance between the top of the conductive element embedded in the open cavity and the top cover under the drive of the external stepper axis. The conductive connector is also connected to an external digital micrometer, used to control and display the distance between the top of the conductive element embedded in the open cavity and the top cover via the external digital micrometer.

[0025] Furthermore, a method for detecting the thickness or curvature of minute gaps in a curved surface based on claim 2 includes the following steps: Under the condition of fixed conductor curvature, the output voltage of the signal processing circuit corresponding to the current gap thickness is measured, and the gap thickness information is obtained based on the monotonic mapping relationship between the output voltage and the gap thickness.

[0026] Under the condition of fixed gap thickness, the output voltage of the signal processing circuit corresponding to the current curvature of the conductor is measured. Based on the monotonic mapping relationship between the output voltage and the curvature, the curvature information of the conductor is obtained. Figure 4 The diagram illustrates the design of a sensing device for measuring the oil film thickness of a space bearing, as provided by this invention. When the outer ring of the bearing is the stator and the inner ring is the rotor, as... Figure 5 and Figure 6As shown, this invention integrates the sensing device into the inner track of the bearing's outer ring, and the sensing element is connected to the subsequent signal processing circuit via an outgoing channel. When the bearing is operating, the thickness of the lubricating oil film can be characterized by measuring the relative distance between the sensing element and the bearing's rolling elements. This miniaturized integrated design of the sensing device helps to achieve micron-level measurement of the lubricating oil film thickness without disrupting the bearing's operating state or lubrication performance. Similarly, when the bearing's outer ring is a rotor and the inner ring is a stator, the sensing element can be integrated onto the bearing's inner ring. The above is only one embodiment provided by this invention. For operating conditions with the same detection requirements, corresponding sensing device shapes can be designed to achieve the measurement of the thickness of curved surface gaps or the curvature of unknown conductors under different requirements. In other words, the shape of the sensing device of this invention matches the inner track of the bearing's outer ring or the shape of the bearing's inner ring.

[0027] In summary, under the condition of a fixed conductor curvature, gap thickness information is obtained by measuring the output impedance of the sensing element corresponding to different micro-gap thicknesses. Under the condition of a fixed micro-gap thickness, the curvature information of the surface is obtained by measuring the output voltage of the sensing element corresponding to conductors with different curvatures. Furthermore, the sensing element in the sensing device does not directly contact the liquid film, enabling the detection of micro-gap thickness or conductor curvature without damaging the measured surface or the state of the liquid film.

[0028] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A method for detecting minute gaps or curvature on a curved surface, characterized in that, Before detection, the sensitive element and the conductor are set to be coaxial. When the distance between the sensitive element and the conductor axis, i.e. the gap thickness or the curvature of the conductor, changes, the intensity of the eddy current generated on the surface of the conductor changes, which leads to a change in the impedance of the sensitive element and in turn to a change in the output voltage of the signal processing circuit.

2. The method for detecting minute gaps or curvature of a curved surface as described in claim 1, characterized in that, Includes the following steps: When the curvature of a conductor surface is constant, the output voltage of the signal processing circuit corresponding to the current gap thickness is measured. Based on the monotonic mapping relationship between the output voltage and the gap thickness, the gap thickness information is obtained. With a fixed gap thickness between the sensitive element and the conductor, the output voltage of the signal processing circuit corresponding to the current curvature of the conductor is measured. Based on the monotonic mapping relationship between the output voltage and the curvature, the curvature information of the conductor is obtained.

3. The method for detecting minute gaps or curvature of a curved surface as described in claim 1, characterized in that, When the curvature of the conductor remains constant, the impedance of the sensing element changes as the gap thickness changes, which in turn causes the output voltage of the signal processing circuit to change. At the same time, the output voltage when the gap thickness is 0 is taken as the zero-point voltage of the sensing device. When the gap thickness remains constant, the impedance of the sensing element changes with the curvature of the conductor, which in turn causes the output voltage of the signal processing circuit to change. Meanwhile, the output voltage when the radius of curvature is infinite, i.e., when it is a plane, is taken as the zero-point voltage of the sensing device.

4. A sensing device for minute gaps or curvatures on a curved surface, characterized in that, It includes a sensitive element, a package, and a signal processing circuit; the sensitive element is used to acquire information about the thickness or curvature of the minute gap between the conductor and the sensitive element; the signal processing circuit is used to acquire information about the thickness or curvature of the minute gap between the conductor and the sensitive element based on the impedance information of the sensitive element. Among them, when the measurement conditions are bearing oil film thickness or bearing rolling element curvature, when the conductor is the bearing rolling element and the outer ring of the bearing is the stator and the inner ring is the rotor, the sensitive element and its package are integrated into the inner track of the outer ring of the bearing. When the conductor is the rolling element of the bearing and the outer ring of the bearing is the rotor and the inner ring is the stator, the sensitive element and its package are integrated into the inner ring of the bearing.

5. A sensing device for a curved surface with minute gaps or curvature as described in claim 4, characterized in that, The shape of the package matches the inner track of the bearing outer ring or the outer shape of the bearing inner ring; the sensitive element is an eddy current detection coil, and the package is made of non-conductive material.

6. An experimental apparatus for detecting minute gaps or curvatures in a curved surface, characterized in that, The sensing device, together with the conductive connector, liquid seal, liquid reservoir, and sensor fixing component, constitutes the experimental apparatus. The sensing device includes a sensitive element, a top cover, an inner core, an outer shell, and a signal processing circuit. The sensitive element is located at the top of the inner core and is placed together with the inner core in a packaged cavity formed by the top cover and the outer shell. The signal processing circuit is located outside the packaged cavity. The upper end of the liquid seal forms an open cavity, and after one end of the conductor is fixed to the conductor connector, the other end is placed into the open cavity and forms a transition fit with the inner wall of the open cavity, so that a sealed liquid cavity is formed between the conductor and the bottom of the open cavity; the liquid storage tank is installed on the side of the liquid seal and communicates with the liquid cavity; the top of the top cover is connected to the bottom of the liquid seal by a thread; the sensing device is fixedly installed on the sensor fixture by the top cover.

7. The experimental apparatus for a small gap or curvature of a curved surface as described in claim 6, characterized in that, The conductive connector is fixedly connected to an external stepper axis and is used to adjust the distance between the top of the conductive body embedded in the open cavity and the top cover under the drive of the external stepper axis. In addition, the conductive connector is also connected to an external digital display micrometer and is used to control and display the distance between the top of the conductive body embedded in the open cavity and the top cover through the external digital display micrometer.

8. The experimental apparatus for a small gap or curvature of a curved surface as described in claim 6, characterized in that, When measuring the curvature of a conductive surface, it is only necessary to set the sensitive element to be coaxial with the conductor. Under the condition of a certain gap thickness, the curvature of the conductive surface can be measured without the need for liquid seals and oil tanks.

9. The experimental apparatus for a small gap or curvature of a curved surface as described in claim 6, characterized in that, The liquid storage tank is used to release liquid medium into the liquid cavity, so that the end of the conductor placed in the open cavity is covered with a liquid film.

10. The experimental apparatus for a small gap or curvature of a curved surface as described in claim 6, characterized in that, The inner core, the bottom of the outer shell, and the inside of the sensor fixture are all equipped with lead-out channels for the sensitive element to connect to the signal processing circuit.

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