CN113806977B - Noise vibration analysis method and system for automobile cooling fan - Google Patents
Noise vibration analysis method and system for automobile cooling fan Download PDFInfo
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- 238000001816 cooling Methods 0.000 title claims abstract description 119
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- 238000010586 diagram Methods 0.000 description 1
- 210000005069 ears Anatomy 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
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Abstract
The invention provides a noise vibration analysis method and a system of an automobile cooling fan, wherein the analysis method comprises the following steps: calculating an unbalance excitation load according to the unbalance parameter of the cooling fan; selecting a preset noise response point and a preset vibration response point; establishing a response evaluation standard database according to the preset noise response points and the preset vibration response points; constraining all degrees of freedom of four tire grounding points of the whole vehicle, applying unbalanced excitation load at the mass center of a cooling fan, and respectively carrying out response analysis on a preset noise response point and a preset vibration response point to obtain a response sound pressure value of the preset noise response point and a response vibration value of the preset vibration response point; based on the response evaluation criterion database, the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point are evaluated and analyzed to judge whether the noise and vibration of the cooling fan meet the noise vibration criterion or not, and the accuracy of the judgment result can be ensured.
Description
Technical Field
The invention relates to the field of automobiles, in particular to a noise vibration analysis method and system of an automobile cooling fan.
Background
With the rapid development of the domestic automobile industry, the NVH performance requirements of consumers on automobiles are continuously improved. Automobile vibration and noise performance in automobiles are increasingly receiving attention from various large automobile enterprises. Engine cooling fans are a major source of noise and vibration, and when they are operated at high speeds, unbalanced forces are generated which can produce noise and vibration in the cab, severely affecting the comfort of personnel in the vehicle. Therefore, it is necessary to evaluate and analyze noise vibration of the cooling fan.
At present, the evaluation analysis of the noise vibration of the cooling fan is carried out through human subjective evaluation and feeling after the actual vehicle is manufactured, if the noise vibration level of the cooling fan is estimated to be too bad, the fan rotating speed is adjusted or the cooling fan structure and even the vehicle body structure are changed to improve the noise and vibration in the vehicle, so that the evaluation result of the noise vibration is easily influenced by subjective factors of the human body to cause inaccurate evaluation, the actual vehicle adjustment is carried out on the fan or the vehicle structure later, the manpower and material resources are wasted, and the influence of the cooling fan excitation on the noise vibration in the vehicle is needed to be considered in the design stage.
Disclosure of Invention
The invention aims to provide a noise vibration analysis method and system of an automobile cooling fan, which are used for solving the problems that the evaluation result of noise vibration of the cooling fan in the prior art is easily influenced by subjective factors of human bodies, so that the evaluation is inaccurate, and the actual adjustment is required to be carried out on the fan or the automobile structure in the follow-up process, so that manpower and material resources are wasted.
The invention provides a noise vibration analysis method of an automobile cooling fan, which comprises the following steps:
establishing a finite element model of the whole vehicle;
acquiring a CATIA model of a cooling fan and CATIA data, wherein the CATIA data comprises unbalance parameters;
introducing a CATIA model of the cooling fan into a finite element model of the whole vehicle;
calculating an unbalance excitation load according to the unbalance parameter of the cooling fan;
selecting a preset noise response point and a preset vibration response point;
constraining all degrees of freedom of four tire grounding points of the whole vehicle, applying the unbalanced excitation load at the mass center of the cooling fan, and respectively performing response analysis on the preset noise response point and the preset vibration response point to obtain a response sound pressure value of the preset noise response point and a response vibration value of the preset vibration response point;
and based on the response evaluation criterion database, evaluating and analyzing the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point to judge whether the noise and vibration of the cooling fan meet the noise vibration criterion.
The noise vibration analysis method of the automobile cooling fan provided by the invention has the following beneficial effects:
the method comprises the steps of establishing a finite element model of a whole vehicle, obtaining a CATIA model of a cooling fan and CATIA data, wherein the CATIA data comprises unbalance parameters, importing the CATIA model of the cooling fan into the finite element model of the whole vehicle, collecting the unbalance parameters of the cooling fan, calculating unbalance excitation loads according to the unbalance parameters of the cooling fan, selecting a preset noise response point and a preset vibration response point, facilitating response monitoring and vibration data acquisition, establishing a response evaluation standard database according to the preset noise response point and the preset vibration response point, restricting all degrees of freedom of four tire grounding points of the whole vehicle by taking data in the response evaluation standard database as response evaluation standard data, applying the unbalance excitation loads at the center of mass of the cooling fan, simulating the vibration condition of the cooling fan under operation excitation, respectively carrying out response analysis on the preset noise response point and the vibration response point to obtain a response value of the preset noise response point and the preset vibration response point, carrying out accurate judgment on whether the vibration response value of the fan accords with the vibration response standard, and judging whether the vibration response value of the preset noise response point and the vibration response value of the preset vibration point can be accurately judged.
The invention can simulate the noise and vibration conditions of the cooling fan generated by the whole vehicle under unbalanced excitation load in real time, can reflect the working condition of the whole vehicle in real time, ensures the response reliability, selects the preset noise response point and the preset vibration response point, obtains the noise and vibration condition of the whole vehicle through response analysis, respectively carries out response analysis on the preset noise response point and the preset vibration response point to obtain the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point, obtains an accurate response result, carries out evaluation analysis on the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point based on the response evaluation standard database, judges whether the noise and vibration of the cooling fan meet the noise vibration standard, accurately judges whether the noise and vibration of the whole vehicle meet the standard, ensures the accuracy of the judgment result, and greatly improves the manufacturing efficiency.
In addition, the noise vibration analysis method of the automobile cooling fan provided by the invention can also have the following additional technical characteristics:
further, the step of obtaining the response sound pressure value of the preset noise response point by performing response analysis on the preset noise response point includes:
acquiring whole vehicle model data and in-vehicle acoustic cavity data, wherein the whole vehicle model data comprise the mass, damping and rigidity of a whole vehicle model, and the in-vehicle acoustic cavity data comprise the mass, damping and rigidity of in-vehicle acoustic cavity fluid;
monitoring and collecting target response data of the preset noise response points in real time, wherein the target response data comprise vibration displacement, vibration speed and vibration acceleration;
and calculating a response sound pressure value of the preset noise response point according to the whole vehicle model data, the sound cavity data in the vehicle, the target response data and the unbalanced excitation load, wherein a calculation formula is as follows:
wherein the method comprises the steps of,[M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]For the rigidity matrix of the whole vehicle, F is an unbalanced excitation load vector, F sf Is the sound pressure load at the critical surface of the vehicle body, { u } is the vibration acceleration of the preset noise response point,for the vibration velocity of the preset noise response point, { u } is the vibration displacement vector of the preset noise response point, [ M ] f ]Is the mass matrix of the fluid in the acoustic cavity of the vehicle, [ C ] f ]Damping matrix for fluid in acoustic cavity in car, [ K ] f ]Is the stiffness matrix of the fluid in the acoustic cavity of the vehicle, and { p } is the sound pressure vector of the preset noise response point.
Further, the step of performing response analysis on the preset vibration response point to obtain a response vibration value of the preset vibration response point includes:
according to the whole vehicle model data and the unbalanced excitation load, calculating to obtain a response sound pressure value of the preset noise response point, wherein a calculation formula is as follows:
wherein [ M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]And the rigidity matrix of the whole vehicle is obtained, wherein { F } is an unbalanced excitation load vector, and { v } is a vibration vector of the vibration response point.
Further, the step of judging whether the noise of the cooling fan meets the noise standard by performing evaluation analysis on the response sound pressure of the preset noise response point and the response vibration of the preset vibration response point based on the response evaluation criterion database includes:
acquiring a preset sound pressure threshold value and a preset vibration threshold value from the response evaluation standard database;
comparing and analyzing the response sound pressure value of the noise response point and the response vibration value of the vibration response point with the preset sound pressure threshold value and the preset vibration threshold value respectively;
judging whether the following are simultaneously satisfied: the response sound pressure value of the noise response point is smaller than the preset sound pressure threshold value, and the response vibration value of the vibration response point is smaller than the preset vibration threshold value;
if yes, judging that the noise and vibration of the cooling fan accord with noise vibration standards.
Further, the step of selecting the preset noise response point and the preset vibration response point includes:
selecting the outer ear of a driver and a passenger as a preset noise response point;
selecting a preset position point on a steering wheel as a first vibration response point;
selecting a preset guide rail of the seat as a second vibration response point;
wherein the preset vibration response points comprise a first vibration response point and a second vibration response point.
Further, the step of importing the CATIA model of the cooling fan into the finite element model of the whole vehicle includes:
modeling the cooling fan with a rigid unit;
the cooling fan is connected to the vehicle body system through a center of mass of the cooling fan.
Further, in the step of calculating an unbalance excitation load based on the unbalance parameter of the cooling fan:
the calculation formula of the unbalanced excitation load is as follows:
F＝(4π 2 mr)f 2 ，
wherein m is the rotor mass of the cooling fan, r is the eccentricity of the cooling fan, f is the frequency of rotation of the cooling fan, and mr is the unbalance parameter of the cooling fan.
The invention provides a noise vibration analysis system of an automobile cooling fan, which is characterized by comprising the following components:
modeling module: the finite element model is used for building the whole vehicle;
the acquisition module is used for: a CATIA model for acquiring cooling fans and CATIA data, the CATIA data comprising an unbalance parameter;
and an importing module: the CATIA model is used for guiding the cooling fan into the finite element model of the whole vehicle;
the calculation module: for calculating an unbalance excitation load based on the unbalance parameters of the cooling fan;
and (3) selecting a module: the method comprises the steps of selecting a preset noise response point and a preset vibration response point;
and an analysis module: the method comprises the steps of restraining all degrees of freedom for four tire grounding points of the whole vehicle, applying the unbalanced excitation load at the center of mass of the cooling fan, and respectively carrying out response analysis on the preset noise response point and the preset vibration response point to obtain a response sound pressure value of the preset noise response point and a response vibration value of the preset vibration response point;
and a judging module: and the system is used for evaluating and analyzing the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point based on the response evaluation standard database to judge whether the noise and vibration of the cooling fan meet the noise vibration standard.
Further, the analysis module is further configured to:
acquiring whole vehicle model data and in-vehicle acoustic cavity data, wherein the whole vehicle model data comprise the mass, damping and rigidity of a whole vehicle model, and the in-vehicle acoustic cavity data comprise the mass, damping and rigidity of in-vehicle acoustic cavity fluid;
monitoring and collecting target response data of the preset noise response points in real time, wherein the target response data comprise vibration displacement, vibration speed and vibration acceleration;
and calculating a response sound pressure value of the preset noise response point according to the whole vehicle model data, the sound cavity data in the vehicle, the target response data and the unbalanced excitation load, wherein a calculation formula is as follows:
wherein [ M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]For the rigidity matrix of the whole vehicle, F is an unbalanced excitation load vector, F sf Is the sound pressure load at the critical surface of the vehicle body, { u } is the vibration acceleration of the preset noise response point,for the vibration velocity of the preset noise response point, { u } is the vibration displacement vector of the preset noise response point, [ M ] f ]Is the mass matrix of the fluid in the acoustic cavity of the vehicle, [ C ] f ]Damping matrix for fluid in acoustic cavity in car, [ K ] f ]Is the stiffness matrix of the fluid in the acoustic cavity of the vehicle, and { p } is the sound pressure vector of the preset noise response point.
Further, the analysis module is further configured to:
according to the whole vehicle model data and the unbalanced excitation load, calculating to obtain a response sound pressure value of the preset noise response point, wherein a calculation formula is as follows:
wherein [ M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]And the rigidity matrix of the whole vehicle is obtained, wherein { F } is an unbalanced excitation load vector, and { v } is a vibration vector of the vibration response point.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a flow chart of a method for analyzing noise vibration of an automotive cooling fan according to an embodiment of the present invention;
fig. 2 is a system block diagram of a noise vibration analysis system of an automotive cooling fan according to an embodiment of the present invention.
Detailed Description
In order that the objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Several embodiments of the invention are presented in the figures. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Referring to fig. 1, an embodiment of the invention provides a noise vibration analysis method of an automobile cooling fan, which includes steps S101 to S107.
S101, establishing a finite element model of the whole vehicle.
The finite element model of the whole vehicle comprises a vehicle body system, a chassis system, tires and a power transmission system.
S102, CATIA model of the cooling fan and CATIA data are acquired, wherein the CATIA data comprise unbalance parameters.
And S103, importing the CATIA model of the cooling fan into the finite element model of the whole vehicle.
The step of importing the CATIA model of the cooling fan into the finite element model of the whole vehicle comprises the following steps:
modeling the cooling fan with a rigid unit;
the cooling fan is connected to the vehicle body system through a center of mass of the cooling fan.
S104, calculating an unbalance excitation load according to the unbalance parameter of the cooling fan.
Wherein, in the step of calculating an unbalance excitation load based on the unbalance parameter of the cooling fan:
the calculation formula of the unbalanced excitation load is as follows:
F＝(4π 2 mr)f 2 ，
wherein m is the rotor mass of the cooling fan, r is the eccentricity of the cooling fan, f is the frequency of rotation of the cooling fan, and mr is the unbalance parameter of the cooling fan.
Theoretically, the smaller the unbalance parameter should be, the better, but due to manufacturing process problems the unbalance parameter cannot be infinitely small, such as a typical double fan unbalance of 2.5g cm.
S105, selecting a preset noise response point and a preset vibration response point.
The step of selecting the preset noise response point and the preset vibration response point comprises the following steps:
selecting the outer ear of a driver and a passenger as a preset noise response point;
selecting a preset position point on a steering wheel as a first vibration response point;
selecting a preset guide rail of the seat as a second vibration response point;
wherein the preset vibration response points comprise a first vibration response point and a second vibration response point.
Specifically, the positions of the outer ring of the left guide rail and the steering wheel of the seat in the directions of 12 points and 3 points are selected as vibration response points, the outer ear positions of a driver and front and rear passengers are selected as noise response points, and the response evaluation criteria are as follows: the noise sound pressure value of the noise response point (i.e. the human ear) should be less than 39dB (a), the idle vibration value of the first vibration response point (i.e. the steering wheel) should be less than 0.5mm/s, and the idle vibration value of the second vibration response point (i.e. the seat track) should be less than 0.1mm/s.
S106, restraining all degrees of freedom of four tire grounding points of the whole vehicle, applying the unbalanced excitation load at the center of mass of the cooling fan, and respectively carrying out response analysis on the preset noise response point and the preset vibration response point to obtain a response sound pressure value of the preset noise response point and a response vibration value of the preset vibration response point.
Wherein, the sound vibration transfer function is:wherein, H represents structural noise, P represents sound pressure, F represents load, and according to the sound vibration transfer function, the noise in the vehicle and the sound pressure can be judged to form positive feedback, and the noise level in the vehicle can be effectively controlled by reducing the sound pressure.
In the noise response analysis process, the vehicle body system is regarded as an elastomer, the vehicle body vibration drives the fluid (namely air) adjacent to the vehicle body to vibrate and then to be transmitted to the fluid in the vehicle, so that the sound pressure change in the vehicle is generated, and the change of the sound pressure in the vehicle can in turn excite the vibration of the vehicle body wall plate, so that the vehicle body becomes a coupling system for the interaction of the vehicle body structure and the fluid in the sound cavity, and the specific analysis is as follows:
acquiring whole vehicle model data and in-vehicle acoustic cavity data, wherein the whole vehicle model data comprise the mass, damping and rigidity of a whole vehicle model, and the in-vehicle acoustic cavity data comprise the mass, damping and rigidity of in-vehicle acoustic cavity fluid;
monitoring and collecting target response data of the preset noise response points in real time, wherein the target response data comprise vibration displacement, vibration speed and vibration acceleration;
and calculating a response sound pressure value of the preset noise response point according to the whole vehicle model data, the sound cavity data in the vehicle, the target response data and the unbalanced excitation load, wherein a calculation formula is as follows:
in the formula, [ M ] s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]For the rigidity matrix of the whole vehicle, F is an unbalanced excitation load vector, F sf Is the sound pressure load at the critical surface of the vehicle body, { u } is the vibration acceleration of the preset noise response point,for the vibration velocity of the preset noise response point, { u } is the vibration displacement vector of the preset noise response point, [ M ] f ]Is the mass matrix of the fluid in the acoustic cavity of the vehicle, [ C ] f ]Damping matrix for fluid in acoustic cavity in car, [ K ] f ]Is the stiffness matrix of the fluid in the acoustic cavity of the vehicle, and { p } is the sound pressure vector of the preset noise response point.
Because the human ear periosteum is sensitive to the sound pressure, the sound pressure and the sound pressure change in the vehicle under the condition of vibration cannot be accurately reflected by the traditional acoustic transmission calculation method.
Further, vibration response analysis is performed on the preset vibration response points through a dynamics principle, and the analysis is as follows:
according to the whole vehicle model data and the unbalanced excitation load, calculating to obtain a response sound pressure value of the preset noise response point, wherein a calculation formula is as follows:
in the formula, [ M ] s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]And the rigidity matrix of the whole vehicle is obtained, wherein { F } is an unbalanced excitation load vector, and { v } is a vibration vector of the vibration response point.
S107, based on the response evaluation criterion database, evaluating and analyzing the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point to judge whether the noise and vibration of the cooling fan meet the noise vibration criterion.
Wherein the step of judging whether the noise of the cooling fan meets the noise standard based on the response sound pressure of the preset noise response point and the response vibration of the preset vibration response point by the response evaluation criterion database comprises the following steps:
and acquiring a preset sound pressure threshold value and a preset vibration threshold value from the response evaluation standard database, wherein the preset sound pressure threshold value is the maximum sound pressure value which can be born under the comfortable state of human ears.
Comparing and analyzing the response sound pressure value of the noise response point and the response vibration value of the vibration response point with the preset sound pressure threshold value and the preset vibration threshold value respectively;
judging whether the following are simultaneously satisfied: the response sound pressure value of the noise response point is smaller than the preset sound pressure threshold value, and the response vibration value of the vibration response point is smaller than the preset vibration threshold value;
if yes, judging that the noise and vibration of the cooling fan accord with noise vibration standards.
In summary, the noise vibration analysis method of the automobile cooling fan provided by the invention has the beneficial effects that: the method comprises the steps of establishing a finite element model of a whole vehicle, obtaining a CATIA model of a cooling fan and CATIA data, wherein the CATIA data comprises unbalance parameters, importing the CATIA model of the cooling fan into the finite element model of the whole vehicle, collecting the unbalance parameters of the cooling fan, calculating unbalance excitation loads according to the unbalance parameters of the cooling fan, selecting a preset noise response point and a preset vibration response point, facilitating response monitoring and vibration data acquisition, establishing a response evaluation standard database according to the preset noise response point and the preset vibration response point, restricting all degrees of freedom of four tire grounding points of the whole vehicle by taking data in the response evaluation standard database as response evaluation standard data, applying the unbalance excitation loads at the center of mass of the cooling fan, simulating the vibration condition of the cooling fan under operation excitation, respectively carrying out response analysis on the preset noise response point and the vibration response point to obtain a response value of the preset noise response point and the preset vibration response point, carrying out accurate judgment on whether the vibration response value of the fan accords with the vibration response standard, and judging whether the vibration response value of the preset noise response point and the vibration response value of the preset vibration point can be accurately judged.
The invention can simulate the noise and vibration conditions of the cooling fan generated by the whole vehicle under unbalanced excitation load in real time, can reflect the working condition of the whole vehicle in real time, ensures the response reliability, selects the preset noise response point and the preset vibration response point, obtains the noise and vibration condition of the whole vehicle through response analysis, respectively carries out response analysis on the preset noise response point and the preset vibration response point to obtain the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point, obtains an accurate response result, carries out evaluation analysis on the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point based on the response evaluation standard database, judges whether the noise and vibration of the cooling fan meet the noise vibration standard, accurately judges whether the noise and vibration of the whole vehicle meet the standard, ensures the accuracy of the judgment result, and greatly improves the manufacturing efficiency.
Referring to fig. 2, the present embodiment provides a noise vibration analysis system of an automobile cooling fan, including:
modeling module: the method is used for building a finite element model of the whole vehicle.
The acquisition module is used for: a CATIA model and CATIA data for acquiring a cooling fan, the CATIA data including an unbalance parameter.
And an importing module: and the CATIA model for the cooling fan is led into the finite element model of the whole vehicle.
Wherein, the import module is further used for:
modeling the cooling fan with a rigid unit;
the cooling fan is connected to the vehicle body system through a center of mass of the cooling fan.
The calculation module: for calculating an unbalance excitation load based on the unbalance parameters of the cooling fan.
Wherein, the calculation formula of the unbalance excitation load is as follows:
F＝(4π 2 mr)f 2 ，
wherein m is the rotor mass of the cooling fan, r is the eccentricity of the cooling fan, f is the frequency of rotation of the cooling fan, and mr is the unbalance parameter of the cooling fan.
And (3) selecting a module: the method is used for selecting a preset noise response point and a preset vibration response point.
The step of selecting the preset noise response point and the preset vibration response point comprises the following steps:
selecting the outer ear of a driver and a passenger as a preset noise response point;
selecting a preset position point on a steering wheel as a first vibration response point;
selecting a preset guide rail of the seat as a second vibration response point;
the preset vibration response points include a first vibration response point and a second vibration response point.
And an analysis module: and the mass center of the cooling fan is used for restraining all degrees of freedom of four tire grounding points of the whole vehicle, applying the unbalanced excitation load, and respectively carrying out response analysis on the preset noise response point and the preset vibration response point to obtain a response sound pressure value of the preset noise response point and a response vibration value of the preset vibration response point.
Wherein the analysis module is further configured to:
acquiring whole vehicle model data and in-vehicle acoustic cavity data, wherein the whole vehicle model data comprise the mass, damping and rigidity of a whole vehicle model, and the in-vehicle acoustic cavity data comprise the mass, damping and rigidity of in-vehicle acoustic cavity fluid;
monitoring and collecting target response data of the preset noise response points in real time, wherein the target response data comprise vibration displacement, vibration speed and vibration acceleration;
and calculating a response sound pressure value of the preset noise response point according to the whole vehicle model data, the sound cavity data in the vehicle, the target response data and the unbalanced excitation load, wherein a calculation formula is as follows:
wherein [ M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]For the rigidity matrix of the whole vehicle, F is an unbalanced excitation load vector, F sf Is the sound pressure load at the critical surface of the vehicle body, { u } is the vibration acceleration of the preset noise response point,for the vibration velocity of the preset noise response point, { u } is the vibration displacement vector of the preset noise response point, [ M ] f ]Is the mass matrix of the fluid in the acoustic cavity of the vehicle, [ C ] f ]Damping matrix for fluid in acoustic cavity in car, [ K ] f ]Is the stiffness matrix of the fluid in the acoustic cavity of the vehicle, and { p } is the sound pressure vector of the preset noise response point.
The analysis module is also configured to:
according to the whole vehicle model data and the unbalanced excitation load, calculating to obtain a response sound pressure value of the preset noise response point, wherein a calculation formula is as follows:
wherein [ M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]And the rigidity matrix of the whole vehicle is obtained, wherein { F } is an unbalanced excitation load vector, and { v } is a vibration vector of the vibration response point.
And a judging module: and the system is used for evaluating and analyzing the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point based on the response evaluation standard database to judge whether the noise and vibration of the cooling fan meet the noise vibration standard.
Wherein, the judging module is further used for:
acquiring a preset sound pressure threshold value and a preset vibration threshold value from the response evaluation standard database;
comparing and analyzing the response sound pressure value of the noise response point and the response vibration value of the vibration response point with the preset sound pressure threshold value and the preset vibration threshold value respectively;
judging whether the following are simultaneously satisfied: the response sound pressure value of the noise response point is smaller than the preset sound pressure threshold value, and the response vibration value of the vibration response point is smaller than the preset vibration threshold value;
if yes, judging that the noise and vibration of the cooling fan accord with noise vibration standards.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (8)
1. A method for analyzing noise vibration of an automotive cooling fan, the method comprising:
establishing a finite element model of the whole vehicle;
acquiring a CATIA model of a cooling fan and CATIA data, wherein the CATIA data comprises unbalance parameters;
introducing a CATIA model of the cooling fan into a finite element model of the whole vehicle;
calculating an unbalance excitation load according to the unbalance parameter of the cooling fan;
selecting a preset noise response point and a preset vibration response point;
constraining all degrees of freedom of four tire grounding points of the whole vehicle, applying the unbalanced excitation load at the mass center of the cooling fan, and respectively performing response analysis on the preset noise response point and the preset vibration response point to obtain a response sound pressure value of the preset noise response point and a response vibration value of the preset vibration response point;
based on a response evaluation standard database, evaluating and analyzing the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point to judge whether the noise and vibration of the cooling fan accord with noise vibration standards or not;
the step of obtaining the response sound pressure value of the preset noise response point through response analysis of the preset noise response point comprises the following steps:
acquiring whole vehicle model data and in-vehicle acoustic cavity data, wherein the whole vehicle model data comprise the mass, damping and rigidity of a whole vehicle model, and the in-vehicle acoustic cavity data comprise the mass, damping and rigidity of in-vehicle acoustic cavity fluid;
monitoring and collecting target response data of the preset noise response points in real time, wherein the target response data comprise vibration displacement, vibration speed and vibration acceleration;
and calculating a response sound pressure value of the preset noise response point according to the whole vehicle model data, the sound cavity data in the vehicle, the target response data and the unbalanced excitation load, wherein a calculation formula is as follows:
wherein [ M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]For the rigidity matrix of the whole vehicle, F is an unbalanced excitation load vector, F sf Is the sound pressure load at the critical surface of the vehicle body,vibration acceleration for the preset noise response point, +.>For the vibration velocity of the preset noise response point, { u } is the vibration displacement vector of the preset noise response point, [ M ] f ]Is the mass matrix of the fluid in the acoustic cavity of the vehicle, [ C ] f ]Damping matrix for fluid in acoustic cavity in car, [ K ] f ]Is the stiffness matrix of the fluid in the acoustic cavity of the vehicle, and { p } is the sound pressure vector of the preset noise response point.
2. The noise vibration analysis method of an automotive cooling fan according to claim 1, wherein the step of performing a response analysis on the preset vibration response point to obtain a response vibration value of the preset vibration response point includes:
according to the whole vehicle model data and the unbalanced excitation load, calculating to obtain a response sound pressure value of the preset vibration response point, wherein a calculation formula is as follows:
wherein [ M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]And the rigidity matrix of the whole vehicle is obtained, wherein { F } is an unbalanced excitation load vector, and { v } is a vibration vector of the vibration response point.
3. The noise vibration analysis method of an automotive cooling fan according to claim 1, wherein the step of judging whether the noise and vibration of the cooling fan meet noise vibration standards based on evaluation analysis of the response sound pressure value of the preset noise response point and the response vibration value of the preset vibration response point by a response evaluation criterion database comprises:
acquiring a preset sound pressure threshold value and a preset vibration threshold value from the response evaluation standard database;
comparing and analyzing the response sound pressure value of the noise response point and the response vibration value of the vibration response point with the preset sound pressure threshold value and the preset vibration threshold value respectively;
judging whether the following are simultaneously satisfied: the response sound pressure value of the noise response point is smaller than the preset sound pressure threshold value, and the response vibration value of the vibration response point is smaller than the preset vibration threshold value;
if yes, judging that the noise and vibration of the cooling fan accord with noise vibration standards.
4. The noise vibration analysis method of an automotive cooling fan according to claim 1, wherein the step of selecting the preset noise response point and the preset vibration response point includes:
selecting the outer ear of a driver and a passenger as a preset noise response point;
selecting a preset position point on a steering wheel as a first vibration response point;
selecting a preset guide rail of the seat as a second vibration response point;
wherein the preset vibration response points comprise a first vibration response point and a second vibration response point.
5. The noise vibration analysis method of an automotive cooling fan according to claim 1, characterized in that the step of importing the CATIA model of the cooling fan into the finite element model of the entire vehicle comprises:
modeling the cooling fan with a rigid unit;
the cooling fan is connected to the vehicle body system through a center of mass of the cooling fan.
6. The noise vibration analysis method of an automotive cooling fan according to claim 1, wherein in the step of calculating an unbalance excitation load from an unbalance amount parameter of the cooling fan:
the calculation formula of the unbalanced excitation load is as follows:
F＝(4π 2 mr)f 2 ，
wherein m is the rotor mass of the cooling fan, r is the eccentricity of the cooling fan, f is the frequency of rotation of the cooling fan, and mr is the unbalance parameter of the cooling fan.
7. A noise vibration analysis system of an automotive cooling fan, comprising:
modeling module: the finite element model is used for building the whole vehicle;
the acquisition module is used for: a CATIA model for acquiring cooling fans and CATIA data, the CATIA data comprising an unbalance parameter;
and an importing module: the CATIA model is used for guiding the cooling fan into the finite element model of the whole vehicle;
the calculation module: for calculating an unbalance excitation load based on the unbalance parameters of the cooling fan;
and (3) selecting a module: the method comprises the steps of selecting a preset noise response point and a preset vibration response point;
and an analysis module: the method comprises the steps of restraining all degrees of freedom for four tire grounding points of the whole vehicle, applying the unbalanced excitation load at the center of mass of the cooling fan, and respectively carrying out response analysis on the preset noise response point and the preset vibration response point to obtain a response sound pressure value of the preset noise response point and a response vibration value of the preset vibration response point;
and a judging module: the system comprises a response evaluation criterion database, a noise judgment module and a vibration judgment module, wherein the response evaluation criterion database is used for evaluating and analyzing a response sound pressure value of the preset noise response point and a response vibration value of the preset vibration response point to judge whether the noise and vibration of the cooling fan accord with noise vibration criteria or not;
wherein the analysis module is further configured to:
acquiring whole vehicle model data and in-vehicle acoustic cavity data, wherein the whole vehicle model data comprise the mass, damping and rigidity of a whole vehicle model, and the in-vehicle acoustic cavity data comprise the mass, damping and rigidity of in-vehicle acoustic cavity fluid;
monitoring and collecting target response data of the preset noise response points in real time, wherein the target response data comprise vibration displacement, vibration speed and vibration acceleration;
and calculating a response sound pressure value of the preset noise response point according to the whole vehicle model data, the sound cavity data in the vehicle, the target response data and the unbalanced excitation load, wherein a calculation formula is as follows:
wherein [ M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]For the rigidity matrix of the whole vehicle, F is an unbalanced excitation load vector, F sf Is the sound pressure load at the critical surface of the vehicle body,vibration acceleration for the preset noise response point, +.>For the vibration velocity of the preset noise response point, { u } is the vibration displacement vector of the preset noise response point, [ M ] f ]Is the mass matrix of the fluid in the acoustic cavity of the vehicle, [ C ] f ]Damping matrix for fluid in acoustic cavity in car, [ K ] f ]Is the rigidity matrix of the fluid in the acoustic cavity of the vehicle, { pAnd the sound pressure vector of the preset noise response point.
8. The noise vibration analysis system of an automotive cooling fan of claim 7, wherein the analysis module is further configured to:
according to the whole vehicle model data and the unbalanced excitation load, calculating to obtain a response sound pressure value of the preset vibration response point, wherein a calculation formula is as follows:
wherein [ M s ]Is the mass matrix of the whole vehicle [ C ] s ]Is the damping matrix of the whole vehicle [ K ] s ]And the rigidity matrix of the whole vehicle is obtained, wherein { F } is an unbalanced excitation load vector, and { v } is a vibration vector of the vibration response point.
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