Supercharger floating ring bearing oil film thickness testing method

Abstract

The invention provides a supercharger floating ring bearing oil film thickness testing method, which comprises the following steps: calculating the outer ring oil film thickness at a bearing body measuring point position, and calculating a first eccentric distance and a first deviation angle of a floating ring based on a floating ring bearing outer ring oil film thickness distribution formula, obtaining the outer ring oil film thickness of the floating ring bearing according to the first eccentric distance and the first deviation angle; calculating and deducing the displacement at the shaft neck based on the dynamical model of the supercharger rotor, obtaining the inner ring oil film thickness at the same measuring point position according to the displacement difference between the shaft neck and the floating ring, and calculating to obtain a second eccentric distance and a second deviation angle of the floating ring based on a floating ring bearing inner ring oil film thickness distribution formula; and obtaining the inner ring oil film thickness of the floating ring bearing according to the second eccentric distance and the second deviation angle. According to the application, the oil film thickness of the floating ring bearing can be accurately tested, and the bearing capacity and durability of the bearing can be improved, so that the operation reliability and performance of a supercharger are greatly improved.

Description

Technical Field

[0001] This application belongs to the technical field of superchargers, and particularly relates to a method for measuring the oil film thickness of a floating ring bearing of a supercharger. Background Art

[0002] The oil film thickness of a supercharger bearing determines the vibration characteristics of the shafting and is a key parameter affecting its operating state. The distribution of the bearing oil film thickness changes with the operating state of the rotor. Obtaining the real-time distribution of the bearing oil film thickness is a necessary condition for analyzing the oil film pressure distribution and the static and dynamic characteristics parameters of bearing lubrication. However, the compact structure of the supercharger and the inner and outer double-layer oil film form of the floating ring bearing both pose difficulties in measuring the oil film thickness, resulting in the lack of an effective oil film thickness measurement method at present. Summary of the Invention

[0003] In view of this, this application aims to propose a method for measuring the oil film thickness of a floating ring bearing of a supercharger to solve the problem of difficult oil film measurement of the floating ring bearing.

[0004] To achieve the above object, the technical solution of this application is realized as follows: This application provides a method for measuring the oil film thickness of a floating ring bearing of a supercharger, including: Calculating the outer oil film thickness at the measuring point position of the bearing body, and calculating the first eccentricity and the first angular displacement of the floating ring based on the outer oil film thickness distribution formula of the floating ring bearing, and obtaining the outer oil film thickness of the floating ring bearing from the first eccentricity and the first angular displacement; Calculating and deriving the displacement at the journal based on the established dynamic model of the supercharger rotor, obtaining the inner oil film thickness at the same position according to the displacement difference between the journal and the floating ring, and calculating the second eccentricity and the second angular displacement of the floating ring based on the inner oil film thickness distribution formula of the floating ring bearing, and obtaining the inner oil film thickness of the floating ring bearing from the second eccentricity and the second angular displacement.

[0005] Further, a pair of eddy current sensors are vertically installed on the bearing body at the floating ring bearing, and a rectangular coordinate system is established with the center of the bearing bush as the origin, where the horizontal direction is the axis and the vertical direction is the axis; Measuring the distances between the probes of the two eddy current sensors and the inner surface of the bearing bush, and the distances between the probes of the two eddy current sensors and the outer surface of the floating ring, and calculating the outer oil film thickness at the measuring point positions of the two eddy current sensors according to the oil film thickness formula. The oil film thickness formulas are as follows: ; ; In the formula, represents from The oil film thickness of the outer ring of the floating ring bearing at the position 135° counterclockwise from the start of the shaft, represents the distance between the end face of the sensor probe and the surface of the floating ring at the 135° position, represents the distance between the sensor probe and the inner surface of the bearing bush at the 135° position; In the formula, represents from The oil film thickness of the outer ring of the floating ring bearing at the position 45° counterclockwise from the start of the shaft, represents the distance between the end face of the probe and the outer surface of the floating ring at the 45° position, represents the distance between the sensor probe and the inner surface of the bearing bush at this position.

[0006] Furthermore, the oil film thicknesses of the outer ring of the floating ring bearing at the two measuring point positions calculated are and substituted into the oil film thickness distribution formula of the outer ring of the floating ring bearing. By constructing a system of equations with the oil film thicknesses at different positions, the first eccentricity and the first angular displacement of the floating ring are solved. According to the first eccentricity and the first angular displacement, the oil film thickness of the outer ring of the floating ring bearing is obtained through the oil film thickness distribution formula of the outer ring of the floating ring bearing.

[0007] Furthermore, two threaded holes perpendicular to each other at 90° are machined at the position corresponding to the floating ring bearing on the bearing body at the compressor end of the supercharger for installing eddy current sensors. The probes of the eddy current sensors are flush with the inner surface of the bearing bush, and the surface of the bearing bush at the probes of the eddy current sensors is sealed with epoxy resin material.

[0008] Furthermore, the oil film thickness distribution formula of the outer ring of the floating ring is: ; In the formula, represents the oil film thickness distribution of the outer ring of the floating ring bearing, represents the first eccentricity of the floating ring, represents the measuring angle, represents the first angular displacement of the floating ring.

[0009] Furthermore, a dynamic model of the supercharger rotor is established using the finite element method, and the dynamic model of the supercharger rotor is corrected through experimental modal analysis to construct the functional relationship of the displacements between the rotor nodes, and the displacement at the journal is deduced from the displacements at other positions of the rotor; The inner oil film thickness at the same measuring point is obtained based on the displacement difference between the journal and the floating ring. By measuring the inner oil film thickness at different positions and calculating the inner oil film thickness distribution of the floating ring bearing according to the inner oil film thickness distribution formula of the floating ring bearing, the second eccentricity and the second angular displacement of the floating ring are solved. According to the second eccentricity and the second angular displacement, the inner oil film thickness of the floating ring bearing is obtained through the outer oil film thickness distribution formula of the floating ring bearing.

[0010] Further, the inner oil film thickness distribution formula of the floating ring bearing is as follows: ; In the formula, represents the outer oil film thickness distribution of the floating ring bearing, represents the second eccentricity of the floating ring, represents the measuring angle, represents the second angular displacement of the floating ring.

[0011] Further, when detecting the inner oil film thickness of the floating ring bearing, a pair of eddy current sensors are vertically installed on the compressor housing to measure the displacement of the compressor end rotating shaft.

[0012] Compared with the prior art, the method for testing the oil film thickness of the floating ring bearing of the supercharger described in this application has the following beneficial effects: The method for testing the oil film thickness of the floating ring bearing of the supercharger described in this application can provide accurate oil film thickness distribution, can deeply understand the interaction between different oil film layers, analyze the dynamic changes of the oil film and its influence on the shafting vibration, can provide a basis for the bearing design of the supercharger, help optimize the lubrication design of the bearing, improve the bearing capacity and durability of the bearing, and thus greatly improve the reliability and performance of the supercharger operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings: Figure 1 is a schematic diagram of the indirect measurement method of two eddy current sensors according to the embodiment of this application; Figure 2 is a structural diagram of the dynamic model of the turbocharger rotor system according to the embodiment of this application; Figure 3 is a schematic diagram of the installation of the eddy current sensor to the bearing body according to the embodiment of this application; Figure 4 is a schematic diagram of the installation of the eddy current sensor to the compressor housing according to the embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] To make the objectives, technical solutions, and advantages of this application more clearly understood, the following further elaborates on this application in detail with reference to specific embodiments and the accompanying drawings.

[0015] It should be noted that unless otherwise defined, the technical terms or scientific terms used in the embodiments of this application should have the ordinary meanings understood by those with ordinary skills in the field to which this application belongs. The "first", "second", and similar terms used in the embodiments of this application do not denote any order, quantity, or importance, but are only used to distinguish different components. Words such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "linked" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to represent relative position relationships, and when the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0016] This embodiment provides a method for testing the oil film thickness of a floating ring bearing of a supercharger. Based on the eddy current method, the oil film thickness of the floating ring bearing at the compressor end of the supercharger is tested. The specific testing method is as follows: By calculating the outer ring oil film thickness at the measuring point position of the bearing body and calculating the first eccentricity and the first angular misalignment of the floating ring based on the outer ring oil film thickness distribution formula of the floating ring bearing, the outer ring oil film thickness of the floating ring bearing is obtained from the first eccentricity and the first angular misalignment; Based on the constructed rotor dynamics model of the supercharger, the displacement at the journal is calculated and derived. According to the displacement difference between the journal and the floating ring, the inner ring oil film thickness at the same position is obtained, and the second eccentricity and the second angular misalignment of the floating ring are calculated based on the inner ring oil film thickness distribution formula of the floating ring bearing. The inner ring oil film thickness of the floating ring bearing is obtained from the second eccentricity and the second angular misalignment.

[0017] The method described in this embodiment can provide an accurate oil film thickness distribution, can deeply understand the interaction between different oil film layers, analyze the dynamic changes of the oil film and its influence on the shafting vibration, can provide a basis for the bearing design of the supercharger, help optimize the lubrication design of the bearing, improve the load-bearing capacity and durability of the bearing, and thus greatly improve the reliability and performance of the supercharger operation.

[0018] Specifically, in this embodiment, during the test of the outer ring oil film thickness distribution of the floating ring bearing, as Figure 3As shown in the figure, two threaded holes perpendicular to each other at 90° are machined on the bearing body at the floating ring bearing, and then a pair of high-precision eddy current sensors are vertically installed. It should be noted that since there is a circle of evenly distributed oil injection holes on the floating ring, in order to avoid the oil film thickness at the position of the oil injection holes exceeding the measurement range of the eddy current sensor, the threaded holes should deviate from the middle position of the floating ring to the end by a certain distance, so as to ensure the accuracy of the measurement.

[0019] At the same time, in order to ensure that it does not exceed the measurement range of the sensor and does not collide with the floating ring, the probe of the eddy current sensor should be as flush as possible with the inner surface of the bearing bush. After the sensor is installed, the surface of the bearing bush at the probe of the sensor is sealed with epoxy resin material to prevent the lubricating oil from leaking from the processing hole and damaging the oil film without affecting the measurement of the sensor.

[0020] As Figure 1 shown, taking the center of the bearing bush as the origin, the horizontal direction as the axis, and the vertical direction as the axis, a rectangular coordinate system is established. The initial distance between the sensor probe and the inner surface of the bearing bush is 、 , and the distance between the surface of the floating ring and the sensor probe is 、 . The two-way sensors should be installed vertically as much as possible and maintain an angle of 90° in the circumferential direction. Here, it is assumed that the sensors are in the directions of 45° and 135° respectively. By measuring the oil film thickness 、 at these two positions, the oil film thicknesses at these two positions are obtained through formulas (1) and (2), and these oil film thicknesses reflect the offset conditions of the floating ring at the 135° and 45° positions.

[0021] Among them, the oil film thicknesses at the measuring points of the two-way sensors can be calculated by formulas (1) and (2): (1) In the formula, represents the oil film thickness of the outer ring of the floating ring bearing at the position 135° counterclockwise from the axis, represents the distance between the end face of the sensor probe and the surface of the floating ring at the 135° position, represents the distance between the sensor probe and the inner surface of the bearing bush at the 135° position.

[0022] (2) In the formula, represents the oil film thickness of the outer ring of the floating ring bearing at the position 45° counterclockwise from the axis, represents the distance between the end face of the probe and the outer surface of the floating ring at the 45° position, It represents the distance from the sensor probe at this position to the inner surface of the bearing bush.

[0023] Oil film thickness distribution of the outer ring of the floating ring bearing It can be expressed by Equation (3): (3) In the formula, is the eccentricity of the floating ring, is the angular misalignment of the floating ring.

[0024] Substitute the oil film thicknesses at the 135° and 45° positions shown in Equations (1) and (2) into Equation (3), and the eccentricity of the floating ring and the angular misalignment can be solved. Furthermore, the oil film thickness of the outer ring of the floating ring bearing can be obtained through Equation (3).

[0025] Furthermore, since Equation (3) describes the distribution form of the oil film thickness rather than the specific oil film thickness value, the goal is to relate the two oil film thickness data to the formula and solve for the eccentricity and angular misalignment of the floating ring.

[0026] Substitute the known oil film thicknesses and into different positions in the oil film thickness distribution formula. Specifically: The oil film thickness at the 135° position (135°)= ; The oil film thickness at the 45° position (45°)= ; Substitute the oil film thicknesses and into Equation (3) to construct a system of equations, solve these two systems of equations to obtain the eccentricity and the angular misalignment . Based on the determined eccentricity and angular misalignment, and calculate the oil film thickness of the outer ring of the floating ring bearing through Equation (3).

[0027] During the test of the oil film thickness distribution of the inner ring of the floating ring bearing, as Figure 4 shown, by vertically installing a pair of high-precision eddy current sensors on the compressor housing to measure the displacement of the compressor end rotating shaft, a circular nut is machined before the test to replace the lock nut, so that the cross-section at the measuring point is circular to ensure the accuracy of the measurement. And in combination with the supercharger rotor dynamics model and the measurement results of the rotating shaft displacement, the motion trajectory of the floating ring bearing journal is calculated to indirectly realize the oil film thickness distribution of the inner ring.

[0028] Specifically, Figure 2It is a schematic diagram of the dynamic model of the supercharger rotor system. Among them, node 18 is the compressor end, nodes 14-17 are the compressor impeller, node 12 is the compressor end floating ring bearing, and node 11 is the adjacent rotor shaft node.

[0029] The rotor dynamic model of the supercharger is established by using the finite element method, and then the established model is corrected through experimental modal analysis (including modal frequency, modal shape, damping characteristics, etc.). Based on the corrected rotor dynamic model, the functional relationship between the displacements of the rotor nodes is established. Based on the rotor dynamic model of the supercharger, the displacement at the journal can be deduced from the displacements at other positions of the rotor. = , where the function is the displacement relationship established through the dynamic model.

[0030] It should be noted that due to the unknown stiffness and damping coefficients at the bearing, there should be no bearing between the measuring point position and the journal position, otherwise the correlation between the two positions cannot be directly established through the rotor model.

[0031] The oil film thickness of the inner ring of the floating ring bearing is calculated by the displacement difference between the journal and the floating ring: (4) In the formula, represents the displacement at the journal, represents the displacement at the floating ring.

[0032] The oil film thickness distribution is given by the following formula: (5) When calculating the oil film thickness of the inner ring, the same as calculating the oil film thickness of the outer ring, the measured data of the oil film thickness at different angles (consistent with the measuring point angles when calculating the oil film thickness of the outer ring, i.e., 45° and 135°) are respectively substituted into formula (5) to construct a system of equations, and the eccentricity and the offset angle of the floating ring are solved. Based on the determined eccentricity and offset angle, the oil film thickness of the inner ring of the floating ring bearing is calculated through formula (5).

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention.

[0034] Embodiments of the present application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application shall be included within the protection scope of the present application.

Claims

1. A method for testing the oil film thickness of a supercharger floating ring bearing, characterized in that: include: The outer ring oil film thickness at the measuring point of the bearing body is calculated, and the first eccentricity and the first offset angle of the floating ring are calculated based on the distribution formula of the outer ring oil film thickness of the floating ring bearing, and the outer ring oil film thickness of the floating ring bearing is obtained from the first eccentricity and the first offset angle; Based on the constructed supercharger rotor dynamics model, the displacement at the journal is calculated and derived, the inner ring oil film thickness at the same measuring point is obtained through the displacement difference between the journal and the floating ring, and the second eccentricity and second offset angle of the floating ring are calculated based on the floating ring bearing inner ring oil film thickness distribution formula, and the inner ring oil film thickness of the floating ring bearing is obtained from the second eccentricity and the second offset angle.

2. The method according to claim 1, characterized in that: A pair of eddy current sensors are installed vertically on the bearing body of the floating ring bearing. A rectangular coordinate system is established with the center of the bearing as the origin, in which the horizontal direction is Axis, vertical direction is axis; Measure the distance between the two eddy current sensor probes and the inner surface of the bearing, and the distance between the two eddy current sensor probes and the outer surface of the floating ring. Calculate the outer ring oil film thickness at the measuring point of the two eddy current sensors according to the oil film thickness formula. The oil film thickness formulas are as follows: ； ； In the formula, Indicates from The oil film thickness of the outer ring of the floating ring bearing at the position of 135° counterclockwise from the axis, Indicates the distance between the sensor probe end face and the floating ring surface at the 135° position. Indicates the distance from the sensor probe to the inner surface of the bearing at the 135° position; In the formula, Indicates from The oil film thickness of the outer ring of the floating ring bearing at the 45° counterclockwise position of the shaft, Indicates the distance between the probe end face and the outer surface of the floating ring at the 45° position. Indicates the distance from the sensor probe to the inner surface of the bearing at this position.

3. The method according to claim 2, characterized in that: The calculated oil film thickness of the outer ring of the floating ring bearing at the two measuring points and Substitute into the floating ring bearing outer ring oil film thickness distribution formula, construct a group of equations through the oil film thickness at different positions to solve the first eccentricity and the first offset angle of the floating ring, and obtain the outer ring oil film thickness of the floating ring bearing through the floating ring bearing outer ring oil film thickness distribution formula according to the first eccentricity and the first offset angle.

4. The method according to claim 2, characterized in that: Two vertical 90° threaded holes are machined at the positions corresponding to the floating ring bearings on the bearing body at the compressor end of the supercharger to install the eddy current sensor. The probe of the eddy current sensor is flush with the inner surface of the bearing shell, and the bearing shell surface at the probe of the eddy current sensor is sealed with epoxy resin material.

5. The method according to claim 2, characterized in that: The distribution formula of the oil film thickness of the outer ring of the floating ring is: ； In the formula, Indicates the oil film thickness distribution of the outer ring of the floating ring bearing. Indicates the first eccentricity of the floating ring, Indicates the measurement angle, Indicates the first deflection angle of the floating ring.

6. The method according to claim 1, characterized in that: The supercharger rotor dynamics model is established by using the finite element method, and the supercharger rotor dynamics model is modified by experimental modal analysis to construct a functional relationship between the displacements of the rotor nodes, and the displacement at the journal is derived from the displacements at other positions of the rotor; The inner ring oil film thickness at the same measuring point is obtained according to the displacement difference between the journal and the floating ring. The inner ring oil film thickness at different positions is measured and the inner ring oil film thickness distribution of the floating ring bearing is calculated according to the floating ring bearing inner ring oil film thickness distribution formula. The second eccentricity and the second offset angle of the floating ring are obtained by solving the second eccentricity and the second offset angle. The inner ring oil film thickness of the floating ring bearing is obtained according to the floating ring bearing outer ring oil film thickness distribution formula.

7. The method according to claim 6, characterized in that The oil film thickness distribution formula of the inner ring of the floating ring bearing is: ； In the formula, Indicates the oil film thickness distribution of the outer ring of the floating ring bearing. Indicates the second eccentricity of the floating ring, Indicates the measurement angle, Indicates the second deviation angle of the floating ring.

8. The method according to claim 6, characterized in that: When testing the inner ring oil film thickness of the floating ring bearing, a pair of eddy current sensors are vertically installed on the compressor housing to measure the displacement of the compressor end shaft.

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