Time delay prediction method for paroxysmal impact vibration of intermediate bearing under multiple faults

Abstract

The invention discloses a time delay prediction method for paroxysmal impact vibration of an intermediate bearing under multiple faults, which belongs to the technical field of intermediate bearings and comprises the following steps: S1, acquiring parameters of the intermediate bearing; s2, working conditions of paroxysmal impact vibration are calculated according to the parameters of the intermediate bearing, and the rotating speeds of a high-pressure rotor and a low-pressure rotor are determined; s3, calculating the time interval of paroxysmal impact vibration caused by a single fault according to the rotating speed of the high-pressure rotor, the rotating speed of the low-pressure rotor and the parameters of the intermediate bearing; and S4, predicting different types of impact vibration time delays caused by multiple local faults by using the result of S3 and combining the phase difference between different local faults. According to the method, the rotating speed of a high-pressure rotor and the rotating speed of a low-pressure rotor are determined according to the working condition of paroxysmal impact vibration, the time interval of paroxysmal impact vibration is determined according to the process that a single local fault penetrates through two adjacent rollers, and time delay of different types of impact vibration caused by multiple local faults is predicted according to the result.

Description

Technical Field

[0001] The present invention relates to the technical field of intermediate bearings, and particularly to a time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults. Background Art

[0002] Rolling bearings are one of the most critical supporting components in rotating machinery, and their performance directly affects the running stability and service life of equipment. Different from ordinary rolling bearings, as a special type of bearing, intermediate bearings are usually installed between a high-pressure rotor and a low-pressure rotor. Its inner ring is connected to the low-pressure rotor shaft, and the outer ring is connected to the hollow high-pressure rotor shaft. This unique structure causes the inner and outer rings of the intermediate bearing to simultaneously bear the rotational actions of the high-pressure rotor and the low-pressure rotor, resulting in more complex operating conditions. Specifically, ordinary rolling bearings only bear a single rotational speed, while intermediate bearings need to simultaneously cope with two different rotational speeds of the high- and low-pressure rotors, making their dynamic behaviors more complex.

[0003] Intermediate bearings are widely used in high-performance rotating machinery, such as aviation twin-rotor engines and marine twin-rotor engines. Due to complex operating conditions and harsh lubrication conditions, intermediate bearings are extremely prone to local faults such as pitting, cracks, and pits caused by light-load slipping and heavy-load scuffing. Moreover, during the gradual development of weak faults, the intermediate bearing will evolve from a single local fault to multiple local fault states, and multiple local faults will be randomly distributed at different positions on the inner / outer raceways of the bearing. During the operation of the intermediate bearing, if a roller passes through a fault and the roller is in a loaded state, the local fault will trigger a significant impact vibration of the intermediate bearing. Under multiple faults, different faults will trigger different types of impact vibration responses. However, the existing time-delay prediction methods for intermittent impact vibration are not yet mature. Based on this, a time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults is proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults to solve the problems in the background art.

[0005] To achieve the above object, the present invention provides a time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults, including the following steps:

[0006] S1. Obtain the parameters of the intermediate bearing, including the inner ring radius, outer ring radius, and the number of rollers;

[0007] S2. Calculate the working conditions of the intermittent impact vibration according to the parameters of the intermediate bearing, and determine the rotational speeds of the high-pressure rotor and the low-pressure rotor;

[0008] S3. Calculate the time interval of the intermittent impact vibration caused by a single fault according to the high-pressure rotor speed, low-pressure rotor speed, and intermediate bearing parameters;

[0009] S4. Use the time interval of the intermittent impact vibration obtained in S3, and combine the phase difference between different local faults to predict the time delay of different types of impact vibrations caused by multiple local faults.

[0010] Preferably, in S2, the operating conditions of the intermittent impact vibration are determined according to the speed ratio of the high-pressure rotor to the low-pressure rotor, and the specific formula is expressed as:

[0011]

[0012] where λ is the speed ratio of the high-pressure rotor to the low-pressure rotor, R o is the outer radius of the intermediate bearing, R i is the inner radius of the intermediate bearing, N b is the number of rollers of the intermediate bearing, m l is the specific multiple of the harmonic fault frequency in the vibration response of the intermediate bearing.

[0013] Preferably, in S2, the high-pressure rotor speed is determined by the low-pressure rotor speed, and is expressed as:

[0014] ω h = λ × ω l ;

[0015] where ω h is the high-pressure rotor speed, ω l is the low-pressure rotor speed.

[0016] Preferably, in S3, the calculation formula for the time interval of the intermittent impact vibration caused by a single fault is:

[0017]

[0018] where ω c is the rotational speed of the roller of the intermediate bearing.

[0019] Preferably, the calculation formula for the rotational speed of the roller of the intermediate bearing is:

[0020]

[0021] Preferably, in S3, the specific calculation steps for the time interval of the intermittent impact vibration caused by a single fault are:

[0022] 1) When the local fault passes through the j-th roller and catches up with the (j + 1)-th roller, the angle by which the local fault rotates more than the roller is Calculate the time required for the local fault to catch up with the (j + 1)-th roller, which is expressed as:

[0023]

[0024] Among them, (ω h - ω c ) is the relative angular velocity difference between the local fault and the roller;

[0025] 2) At this time, the rotational speed of the local fault is ω h , the total rotation time is Δt, so the total angle of rotation of the local fault is (ω h ×Δt). Then the phase of the (j + 1)-th roller when passing through the local fault lags behind the phase of the j-th roller when passing through the local fault, and the lag angle is expressed as:

[0026] Δθ = 2π - ω h ×Δt;

[0027] 3) At this time, the time required for the phase of all the rollers passing through the local fault to change by one cycle is expressed as:

[0028]

[0029] Among them, Δt is the time required for the j-th roller to pass through the local fault and transform into the (j + 1)-th roller passing through the local fault during a certain conversion process, is the number of conversions between different rollers within one cycle.

[0030] Preferably, the specific steps of S4 are:

[0031] 1) After the local fault n + 1 crosses the j-th roller, calculate the time required for the local fault n to catch up with the j-th roller, which is expressed as:

[0032]

[0033] Among them, (θ pd(n+1) - θ pdn ) is the phase difference between the local fault n + 1 and the local fault n and the angular displacement by which the local fault n rotates more than the roller, and (ω h - ω c ) is the relative angular velocity difference between the local fault n and the roller;

[0034] 2) At this time, the roller passing through the local fault n lags behind the roller passing through the local fault n + 1 in phase. Calculate the total angle of roller rolling, which is expressed as:

[0035] Δθ = Δt×ω c ;

[0036] 3) Calculate the time lag of the roller passing through the local fault n compared to the roller passing through the local fault n+1 based on the time interval of the burst impact vibration caused by a single fault obtained in S3, which is expressed as:

[0037]

[0038] where 2π represents a cycle of the phase change of all the rollers passing through the local fault n, represents the proportion of the lagging phase in one cycle.

[0039] Preferably, the calculation formula for the time delay of different types of impact vibrations caused by multiple local faults is expressed as:

[0040]

[0041] Preferably, in the prediction of the time delay of different types of impact vibrations caused by multiple local faults, if the obtained time delay ΔT>T, then:

[0042] ΔT = mod(ΔT,T);

[0043] where mod(·) is the remainder function.

[0044] Therefore, the present invention relates to a method for predicting the time delay of burst impact vibrations of an intermediate bearing under multiple faults. The high-pressure and low-pressure rotor speeds are determined based on the working conditions of the burst impact vibrations. The time interval of the burst impact vibrations is determined according to the process of a single local fault passing through two adjacent rollers, and the time delay of different types of impact vibrations caused by multiple local faults is predicted based on this result. The prediction method protected by the present invention is simple and has high prediction accuracy.

[0045] Next, through the drawings and embodiments, the technical solutions of the present invention will be further described in detail. Description of the Drawings

[0046] Figure 1 is a flowchart of an embodiment of the present invention;

[0047] Figure 2 is a schematic diagram of the process of a single local fault passing through the jth and j+1st "passing rollers" in an embodiment of the present invention. Among them, (a) is when the local fault starts to pass through the jth roller, (b) is when the local fault surpasses the jth roller, and (c) is when the local fault catches up with the j+1st roller;

[0048] Figure 3 is a vibration waveform diagram of the burst impact vibration caused by a single local fault in an embodiment of the present invention;

[0049] Figure 4This is the real-time phase diagram of "through the roller" and "through and load the roller" in the embodiments of the present invention. Among them, (a) is "through the roller", and (b) is "through and load the roller".

[0050] Figure 5 This is the schematic diagram of the process in which two local faults respectively pass through the j-th "through the roller" in the embodiments of the present invention. Among them, (a) is that local fault 2 starts to pass through the j-th roller, and (b) is that local fault 1 catches up with the j-th roller.

[0051] Figure 6 This is the vibration waveform diagram of the intermittent shock vibration caused by two local faults in the embodiments of the present invention.

[0052] Figure 7 This is the real-time phase diagram of "through the roller" and "through and load the roller" in the case of two local faults in the embodiments of the present invention. Among them, (a) is "through the roller", and (b) is "through and load the roller". Detailed implementation manners

[0053] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0055] Embodiment

[0056] The time-delay prediction is carried out by using the prediction method of the present invention. As Figure 1 shown, the following steps are included:

[0057] S1. Obtain the parameters of the intermediate bearing, the inner ring radius R i = 12.2 mm, the outer ring radius R o = 28 mm, and the number of rollers N b = 10;

[0058] S2. Calculate the working conditions of the intermittent shock vibration according to the parameters of the intermediate bearing, and determine the rotational speeds of the high-pressure rotor and the low-pressure rotor.

[0059] The necessary and sufficient conditions for the intermediate bearing to generate a large-amplitude shock vibration at a certain moment include two parts: (a) There must be a roller passing through the fault, and this type of roller is defined as "through the roller"; (b) The roller must be loaded, and this type of roller is defined as "loaded roller". The roller type that satisfies both of the above conditions is defined as "through and load the roller".

[0060] Specifically, the operating conditions of the intermittent impact vibration are related to the speed ratio of the high-pressure rotor and the low-pressure rotor, and are specifically expressed by the formula:

[0061]

[0062] m l is the specific multiple of the harmonic fault frequency in the vibration response of the intermediate bearing,

[0063] Substitute the data to obtain λ = 1.4943.

[0064] Select the rotational speed ω of the low-pressure rotor l = 1000.03 rad / s, then the rotational speed ω of the high-pressure rotor h = λ × ω l = 1494.35 rad / s;

[0065] Therefore, a set of operating conditions that can generate intermittent impact vibration can be determined as: ω l = 1000.03 rad / s, ω h = λ × ω l = 1494.35 rad / s.

[0066] S3. Calculate the time interval of the intermittent impact vibration caused by a single fault according to the rotational speed of the high-pressure rotor, the rotational speed of the low-pressure rotor, and the parameters of the intermediate bearing; as Figure 2 shown, it is the process of a single fault passing through the j-th and the (j + 1)-th "passing roller", and the relative angle between the two rollers is Since the rotational speed ω h of the outer ring is higher than the rotational speed ω c of the roller, after the outer ring fault passes through the j-th "passing roller", the subsequent event must be that the outer ring fault catches up with the (j + 1)-th "passing roller". The specific calculation steps are as follows:

[0067] 1) As Figure 2 shown in (a), start timing when a single local fault begins to pass through the j-th roller. For the local fault to overtake the j-th roller and catch up with the (j + 1)-th roller to reach the state shown in Figure 2 (c), the angular displacement that the local fault needs to rotate more than the roller is 2π / N b rad. During this process, the time required for the local fault to catch up with the (j + 1)-th roller is:

[0068]

[0069] Among them, (ω h - ω c ) is the relative angular velocity difference between the local fault and the roller;

[0070] 2) At this time, the rotational speed of the local fault in the outer ring is ω h , and the total rotation time is Δt. Therefore, the total angle of rotation of the local fault is (ω h ×Δt). Referring to Figure 2 , the phase of the (j + 1)-th roller when passing through the local fault lags behind the phase of the j-th roller when passing through the local fault. The lag angle is expressed as:

[0071] Δθ = 2π - ω h ×Δt;

[0072] Substitute the data in S2 into the above two equations to obtain Δθ ≈ 0.024343 rad, which is an extremely small angle.

[0073] This indicates that the phase of the (j + 1)-th "passing roller" lags behind the phase of the j-th "passing roller", but the lag angle is an extremely small value. This conversion process will occur repeatedly among the j-th, (j + 1)-th,..., (j + n)-th "passing rollers". That is, the phase of the "passing roller" will slowly decrease in the clockwise direction.

[0074] 3) At this time, the phase change of the "passing roller" for one cycle is 2π rad, and the time required for its phase to change one cycle is:

[0075]

[0076] where Δt is the time required for the j-th "passing roller" to transform into the (j + 1)-th "passing roller" during a certain conversion process, is the number of conversions between different "passing rollers" within one cycle.

[0077] From the above formula, the calculation formula for the time interval of the burst impact vibration caused by a single fault is obtained as:

[0078]

[0079] Substitute the data in step S2 into this calculation formula to obtain ω c = 1344.33 rad / s;

[0080] Furthermore, T = 1.07 s is obtained. Under the above working conditions, the vibration waveform of the burst impact vibration of the intermediate bearing caused by a single local fault is as Figure 3 shown.

[0081] To clearly show the cause of the above burst impact vibration, an experiment is conducted. The real-time phase positions of the "passing roller" and the "passing and loaded roller" are recorded as Figure 4 shown, from Figure 4As can be seen in (a), the phase of the roller passing through the fault (i.e., the "through-roller") gradually decreases in the clockwise direction. The period of the phase change of the "through-roller" is one revolution, i.e., 2π rad. The time required for one period of phase change is T = 1.07 s.

[0082] The simple "through-roller" alone cannot trigger the impact vibration response. The "through-roller" needs to bear the load simultaneously and become the "through and loaded roller" for the intermediate bearing to generate a large impact vibration response. Figure 4 (b) gives the real-time phase record of the "through and loaded roller". It can be seen that only within a specific phase interval section will the "through-roller" become the "through and loaded roller". Therefore, only within these interval sections will a large impact vibration occur.

[0083] S4. Using the time intervals of the burst impact vibrations obtained in S3 and combining with the phase differences between different local faults, predict the time delays of different types of impact vibrations caused by multiple local faults. In this embodiment, taking 2 local faults as an example, the processes of the two local faults passing through the j-th "through-roller" are as Figure 5 shown, and the relative angle between the two rollers is The relative angle between the two local faults is θ pd2 -θ pd1 = π / 18 rad. In addition, the rotational speed ω h of the outer ring is higher than the rotational speed ω c of the roller. Therefore, after local fault 2 passes through the j-th "through-roller", the subsequent event must be that local fault 1 catches up with the j-th "through-roller". The specific steps are as follows:

[0084] 1) In this process, for local fault 1 to catch up with the j-th roller, the angle that local fault 1 needs to rotate more than the roller is (θ pd2 -θ pd1 ). The time required for this process is:

[0085]

[0086] where, (ω h -ω c ) is the relative angular velocity difference between local fault n and the roller;

[0087] 2) At this time, the rotational speed of the roller is ω c , and the total rotation time is Δt. Therefore, the total angle of rotation of the roller is calculated as:

[0088] Δθ = Δt×ω c ;

[0089] Substituting the data gives Δθ = 1.5640 rad.

[0090] 3) Under two local faults, there are two different types of "passing rollers". The "passing roller" passing through local fault 1 lags behind the "passing roller" passing through local fault 2 by a phase difference of Δθ. As Figure 4 can be seen, the phase of the "passing roller" slowly decreases in the clockwise direction. Therefore, the time lag of the "passing roller" passing through local fault 1 compared to the "passing roller" passing through local fault 2 can be expressed as:

[0091]

[0092] where 2π represents one period of the phase change of the "passing roller", represents the proportion of the lagging phase within one period of the phase change of the "passing roller", T represents the time required for one period of the phase change of the "passing roller", which is the same as the time interval of the bursty impact vibration caused by a single fault calculated in step S3;

[0093] Therefore,

[0094] Substituting each data, we get ΔT = 0.27 s. Since ΔT < T, there is no need to perform the remainder function calculation.

[0095] The vibration waveforms of the bursty impact vibration of the intermediate bearing caused by two local faults are as Figure 6 shown. In the case where the outer ring of the intermediate bearing contains two local faults, the two local faults respectively trigger different impact vibration responses, and there is a fixed time delay between the two different types of impact vibration responses.

[0096] To clearly show the reason for the time delay of the bursty impact vibration under two local faults, Figure 7 records of the real-time phase positions of the "passing roller" and the "passing and loaded roller" under two local faults are given. As can be seen from Figure 7 (a) therein, at the same time point, the "passing roller" passing through local fault 1 lags behind the "passing roller" passing through local fault 2 by a phase difference of Δθ. If the two "passing rollers" need to reach the same phase position, the "passing roller" passing through local fault 1 lags behind the "passing roller" passing through local fault 2 by a time difference of ΔT. Similarly, the "passing and loaded roller" passing through local fault 1 lags behind the "passing and loaded roller" passing through local fault 2 by a time difference of ΔT. Therefore, the phase lag of different types of "passing and loaded rollers" causes Figure 6 the time delay phenomenon of different types of impact vibrations in

[0097] Therefore, the present invention relates to a time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults. The high-pressure and low-pressure rotor speeds are determined based on the operating conditions of the intermittent impact vibration. The time interval of the intermittent impact vibration is determined according to the process of a single local fault passing through two adjacent rollers, and the time delay of different types of impact vibrations caused by multiple local faults is predicted based on the result. The prediction method protected by the present invention is simple and has high prediction accuracy.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A time delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults, characterized in that It includes the following steps: S1. Obtain the parameters of the intermediate bearing, including the inner ring radius, outer ring radius, and the number of rollers; S2. Calculate the working conditions of the intermittent impact vibration based on the parameters of the intermediate bearing, and determine the rotational speeds of the high-pressure rotor and the low-pressure rotor; S3. Calculate the time interval of the intermittent impact vibration caused by a single fault according to the rotational speed of the high-pressure rotor, the rotational speed of the low-pressure rotor, and the parameters of the intermediate bearing; S4. Use the time interval of the intermittent impact vibration obtained in S3, and combine the phase differences between different local faults to predict the time delays of different types of impact vibrations caused by multiple local faults.

2. The time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults according to claim 1, wherein: In S2, the working conditions of the intermittent impact vibration are determined according to the rotational speed ratio of the high-pressure rotor to the low-pressure rotor, and the specific formula is expressed as: Among them, λ is the rotational speed ratio of the high-pressure rotor to the low-pressure rotor, R is the outer ring radius of the intermediate bearing, and R i is the inner ring radius of the intermediate bearing, N b is the number of rollers of the intermediate bearing, m l is the specific multiple of the harmonic fault frequency in the vibration response of the intermediate bearing.

3. A time delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults according to claim 2, characterized in that: In S2, the rotational speed of the high-pressure rotor is determined by the rotational speed of the low-pressure rotor, and is expressed as: ω h = λ × ω l ; Among them, ω h is the high-pressure rotor speed, and ω l is the low-pressure rotor speed.

4. A time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults according to claim 3, characterized in that: In S3, the calculation formula for the time interval of the intermittent impact vibration caused by a single fault is: where ω c is the rotational speed of the intermediate bearing roller.

5. A time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults according to claim 4, characterized in that: The calculation formula for the rotational speed of the rollers of the intermediate bearing is:

6. A time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults according to claim 5, characterized in that The specific steps of S4 are: 1) When the local fault n + 1 passes through the jth roller, calculate the time required for the local fault n to catch up with the jth roller, and it is expressed as: Among them, (θ pd(n+1) - θ pdn ) is the angular displacement by which the local fault n rotates more than the roller, and (ω h - ω c ) is the relative angular velocity difference between the local fault n and the roller; 2) At this time, the roller passing through the local fault n lags in phase behind the roller passing through the local fault n + 1. Calculate the total angle of roller rotation, and it is expressed as: Δθ = Δt × ω c ; 3) According to the time interval of the intermittent impact vibration caused by a single fault obtained in S3, calculate the time by which the roller passing through the local fault n lags behind the roller passing through the local fault n + 1, and it is expressed as: Among them, 2π represents a period of all roller phase changes passing through the local fault n, which represents the proportion of the phase lag in one period.

7. A time delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults according to claim 6, characterized in that: The calculation formula for the time delays of different types of impact vibrations caused by multiple local faults is expressed as:

8. A time-delay prediction method for the intermittent impact vibration of an intermediate bearing under multiple faults according to claim 7, characterized in that: In the prediction of the time delays of different types of impact vibrations caused by multiple local faults, if the obtained time delay ΔT > T, then make: ΔT = mod(ΔT, T); where mod(·) is the remainder function.

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