ES2362834B1 - DEVICE ACOUSTIC CHARACTERIZATION TEAM. - Google Patents

Abstract

Acoustic characterization equipment of devices comprising a chamber selected between anechoic and semi-anechoic (1), inside which a frame (4) for holding the test sample (6), a unidirectional electrodynamic vibration equipment (2) located inside a closed insulation compartment (3), and an acoustically absorbent interface (5), consisting of at least one rigid stud (9) and a fixing mesh (10), and connecting the frame (4) to the electrodynamic vibration equipment (2) through holes (11) that are implemented in the upper face of the closed insulation compartment (3) and which are traversed by rigid studs (9).

Description

Acoustic characterization equipment of devices.

Field of the Invention

The present invention has as its main objective the acoustic characterization of devices subjected to vibrations and their application in the field of acoustic and vibration tests for automobile vehicle components. However, its use is not limited to this technological sector, being useful in other areas of the technique in which the measurement tests and characterization of the noise caused by vibration are a functional requirement of a component.

Background of the invention

Electrodynamic vibration systems (European Patent EP1481232) are common test means for automotive vehicle components. With these equipments tests of vibration characterization and mechanical durability of automobile components are carried out with the objective of verifying that they meet the requirements specified by the manufacturer for the life of the component in the vehicle.

At present, and due to the increased interest of the automobile industry for vehicle comfort, progress has been made in improving comfort in different fields, including noise. Therefore, these electrodynamic vibration systems have begun to be used to analyze the acoustic behavior of the automobile vehicle components. Most of these components, when excited by vibration profiles generated by the reproduction of signals acquired on the road or by synthetic profiles generated in the laboratory, can generate noises that must be measured, evaluated and / or characterized.

The use of an electrodynamic vibration system to characterize the acoustic behavior of a vehicle component presents multiple problems since so that these systems can generate the necessary force to subject the test component to the acceleration levels requested in the normative test requirements , high noise levels are generated. Axial acceleration levels are obtained by variations in the power supply of the electrodynamic mechanism of the vibration system. In this way, both by the mechanisms of the vibration system and the intrinsic operation thereof, the displacement of the working surface of the vibration equipment causes the displacement of an air mass generating a high level of noise. This noise is a problem for the acoustic characterization of components and must be isolated to minimize its influence on the acoustic evaluation of the component to be tested in the laboratory.

In the field of vibration tests on automotive vehicle components, electrodynamic vibration systems receive remarkable attention as they allow the generation of the necessary levels of acceleration in one direction, and therefore allow testing of all types of vehicle components. With this equipment, the mass of the assembly formed by the frame and the test component must not be excessively limited, and components of considerable dimensions can be tested (such as a fully equipped door or a dashboard).

Electrodynamic vibration systems can operate in several operating modes (sine vibration, random vibration, reproduction of temporary road profiles) but generally they always work in “closed loop” mode. These systems work by means of an electronic controller and one or several accelerometers positioned on the component (control points), which measure the local vibration levels, sending that information to the controller. This closes the measuring loop and allows the system to regulate its operation and control the acceleration levels in the component during the test.

The vibration controller as disclosed in US2003229738 operates on a logical interface in which two main variables are used, the first variable is the frequency or the range of frequencies in which the system will work and the second variable It is the level of acceleration that the team has to reach. From these two variables, this software and the electronic controller set all the control parameters of the system, as well as the security levels and alerts.

In principle, by proposing a solution to these noise problems presented to us when using these vibration equipment, a commercial electrodynamic vibration system can be used as a valid alternative for the acoustic characterization of automobile vehicle components subjected to vibration. This system can be used as long as it is acoustically insulated and in this way it is possible to control the level of noise generated by the system components (mechanical devices, electrical devices, power amplifier) as well as to minimize the noise caused by the operation of the system. same.

However, these electrodynamic vibration systems (without permanent magnet), with the ability to generate high levels of force and acceleration (forces greater than 10,000 N), have not been widely applied for acoustic characterization due to high noise levels. that generate, which presents a difficult problem to save. This problem makes characterization and noise analysis of the component difficult when it is excited by a vibrating signal and is the starting point of this invention.

There are vibration systems designed to produce low noise levels but they do not have the necessary force (forces below 100 N) to be able to subject the required acceleration levels to the vehicle components, especially for test frame and weight component assemblies. considerably high.

Description of the invention

The present invention proposes as a novelty the use of a high capacity and performance electrodynamic vibration system within a semi-anechoic or anechoic chamber, in which there is a reduced level of background noise (this chamber will be isolated from the outside by panels high acoustic absorption on all faces). The mechanisms of the electrodynamic vibration system are closed inside an acoustically insulated cabin and located inside the semi-anechoic chamber so as not to allow the noise generated by the mechanisms to be emitted outside the cabin. Electrical devices and the power amplifier are installed outside the semi-anechoic chamber. Furthermore, in this isolation compartment of the vibration system, a vibroacoustic interface is implemented as a novel solution to the initial problem, which allows transmitting the vibration generated by the electrodynamic system inside its cabin, to the component located outside it minimizing the transmission of noise In addition, the implemented vibroacoustic interface also allows the components to be positioned in a vehicle position inside the semi-anechoic chamber, in which the analysis and / or acoustic characterization of the component can be performed when subjected to vibratory excitation.

The electrodynamic vibration equipment is located inside a closed cabin that allows its acoustic isolation and through a vibroacoustic interface in which a series of holes are made in which rigid fixations are introduced, the vibration is transmitted to the outside of this cabin This interface allows the transmission of the vibrations of the electrodynamic vibration system, positioned inside the insulated interior, outside the same (inside the semi-anechoic chamber) reducing noise transmission, which is a novelty compared to a system of standard electrodynamic vibrations without isolation, with the function of minimizing the transmission of noise from the mechanism to the enclosure by means of acoustic absorption and by the operation of the acoustic traps that surround the rigid studs. In this way, noise will be controlled in the environment in which the motor vehicle component will be acoustically characterized, taking advantage of the absorption properties of the materials used in the walls of the insulated passenger compartment as well as in the acoustic traps. This solution is composed of the acoustic trap of acoustically absorbent material and the rigid studs that directly transmit the vibrations of the vibration system to the test frame through the hole made in the upper face of the mechanism isolation compartment.

Rigid interface studs are used to transmit the vibrations generated by the electrodynamic system to the test frame. These studs move through the holes in the vibroacoustic interface that function as a link between the vibration equipment and the test frame.

The acoustic traps used in the holes in the interface allow the rigid studs to pass the vibrations from the interior of the isolation compartment to the test frame that is outside, inside the semi-anechoic chamber. These holes are designed to function as acoustic traps, with a rigid multi-perforated material and filling of material with high acoustic absorption coefficient. In this way, it is possible to have a physical connection between the interior and exterior of the isolation compartment of the vibrator mechanisms, reducing the transmission of noise from the mechanisms. In addition, these holes can be closed by tight covers of rigid material when not used in the fixing of the test frame.

Brief description of the drawings

The invention will now be described in a series of figures that help to understand the invention and that expressly relate to an implementation of said invention, which is presented as a non-limiting example of this invention, and in which it is represented:

Figure 1 shows a scheme of acoustic characterization equipment inside a semi-anechoic chamber.

Figure 2 shows a section of the closed isolation cabin.

Figure 3 plan view of the fixing mesh of the vibroacoustic interface.

Figure 4 shows a section of the upper cover of the closed insulation compartment.

Figure 5 shows a perspective view of a rigid stud.

Figure 6 shows a perspective view of a rigid waterproof cover.

Figure 7 shows a perspective view of an orifice.

The following references are represented in the figures indicated:

1-Semi-anechoic chamber

2-Electrodynamic vibration equipment

3-Closed isolation cabin

4-Frame

5-Acoustically absorbent inferfaz

6-Test sample

7-Microphones

8-Test Technician

9-Rigid stud

10-Fixing Mesh

11-Orifices

12-Rigid waterproof caps

13-External communication acoustic trap

Description of a preferred embodiment of the invention

The preferred embodiment of this invention requires the integration in a semi-anechoic chamber (1) of an electrodynamic vibration system (2) as shown in Figure 1. First, a semi-anechoic chamber (1) must be used. ) to isolate the indoor environment from outside noise. This chamber can be built under different constructive solutions using acoustic absorbent materials (rock wool) in order to obtain an enclosure with a low level of background noise. It is also necessary to implement an acoustic trap

(13) to allow aeration of the semi-anechoic chamber (1) and to be able to pass the wiring of the microphones (7) and accelerometers from the inside of the chamber (1) to the outside of it where the system is located acquisition and acoustic analysis as well as the vibration system controller.

The floor of the chamber must be rigid to support the weight of the electrodynamic vibration equipment (this is the reason why the chamber is considered semi-anechoic). The monoaxial electrodynamic vibration device (2) must be positioned centrally. A necessary requirement in the integration of the vibration equipment in the semi-anechoic chamber is to take into account the need to design a cavity in the ground to pass the power cables of the vibration system.

The mechanisms of the vibration system must be introduced into a closed insulated compartment (3) that allows it to be closed by a cover. This cabin (3), represented in Figure 2, can be constructed with the same acoustic absorbent material as the semi-anechoic chamber (1) to allow isolation of the noise generated by the electrodynamic vibration system and thus prevent its transmission and contribution at the level of ambient noise existing inside the semi-anechoic chamber (1).

The test sample (6) will be positioned on a rack or test tool (4) that allows it to be placed in the position it takes in the vehicle, according to the main coordinate axes. This frame (4) will be in charge of supporting the sample and will be the one that transmits the vibrations to the test sample (6), therefore this frame (4) must be well fixed to the vibration system. The vibration equipment (2) will remain inside the isolation compartment (3) and the test sample (6) will be outside it, inside the semi-anechoic chamber (1) To join both components, it is designed and implements an acoustically absorbent inferfaz (5) as a solution used for system interconnection. This interface is composed of rigid studs (9), such as the one shown in Figure 5, whose mission is to transmit the vibrations of the electrodynamic vibration system (2) to the test sample (6) that is outside the cabin (3), and by a fixing mesh (10), represented in Figure 3, which is crossed by rigid studs (9), and whose shape will adapt to the particular mesh of the vibration equipment used, being in this case star-shaped as shown in Figure 3. To make this possible, holes (11) are designed that are implemented in the upper face of the insulating compartment

(3)

as depicted in Figure 4. These holes (11) made for the interface (5) allow the rigid studs (9) to pass, for the transmission of vibrations from the interior of the insulation compartment (3) to the frame

(4)

test that will be found inside the semi-anechoic chamber (1). These holes (11) are designed by a rigid multi-perforated structure filled with acoustic absorbent material so that they also work

as acoustic traps, as shown in Figure 7. These holes (11) can be closed by rigid waterproof covers (12) when not in use, and prevent the transmission of noise from the system inside the semi-chamber. anechoic

The semi-anechoic chamber (1) must be designed so that it has space for a test technician (8) to manipulate and work around the test sample (6), as well as to have room to allow placement, at different distances, of the microphones (7) that allow measuring the noise generated by the component or sample to be tested.

To fix the test frame (4) to the vibration equipment (2), the smallest possible number of rigid studs (9) of the mesh (10), represented in Figure 3, should be used so that the system is capable of controlling the acceleration / frequency levels, as well as supporting the weight of the frame together with the test sample (2). If the number of fixing points through the vibroacoustic interface (5) is minimized, the possible sources of transmission through the frame (4) of high frequency structural noise inside the semi-anechoic chamber (1) will also be reduced. Unused holes (11) will be closed with rigid waterproof caps (12), shown in Figure 6 that will work as obstacles to the transmission of system noise.

As a complement to the reduction of the transmission of structural noise, the system can optionally use elastomeric damping devices on the studs (9). These elastomers are designed with a cut-off frequency higher than the test frequencies for a previously specified load, with the purpose of fi ltering and reducing the possible transmissions of high-frequency structural noise.

Claims (9)

1. Acoustic characterization device that includes:

-

A frame (4) for holding the test sample (6) and

-

A unidirectional electrodynamic vibration device (2) located inside a closed insulated compartment (3),

both located inside a chamber selected from anechoic or semi-anechoic (1), characterized by comprising an acoustically absorbent interface (5) that connects the frame (4) to the electrodynamic vibration equipment (2) through holes (11) which are implemented in the upper face of the closed insulation compartment (3).

2.

Acoustic characterization device according to claim 1, characterized in that the interface (5) is composed of at least one rigid stud (9) that crosses the holes (11), and a fixing mesh (10) for fixing the frame (4). ).

3.

Acoustic characterization device of devices subjected to vibration according to claim 2, characterized in that the fixing mesh (10) has a star shape.

Four.

Acoustic characterization device according to previous claims characterized in that the holes (11) have a rigid multi-perforated structure filled with acoustic absorbent material.

5.

Acoustic characterization device according to previous claims, characterized in that the holes (11) that are not used are closed by means of rigid sealed covers (12).

6.

Acoustic characterization method of devices using the equipment disclosed in claims 1-5 characterized by comprising the steps of:

-

Transmission of the vibration of the electrodynamic vibration equipment (2) to the frame (4) by means of an acoustically absorbent interface (5),

-

Vibration transmission through an acoustically absorbent interface (5), through the holes

(11) from the closed insulation compartment (3), to the frame (4),

-

Transmission of the vibration of the frame (4) to the test sample (6),

-

Measurement of the noise generated by the test sample, with microphones (7).

7.

Acoustic characterization method of devices according to claim 6, characterized in that the transmission of the vibration of the electrodynamic vibration equipment (2) to the frame (4) is carried out through at least one rigid stud (9) supported by a fixing mesh ( 10).

8.

Acoustic characterization method of devices according to claim 6, characterized in that the test sample is a device of a vehicle.

SPANISH OFFICE OF THE PATENTS AND BRAND Application number: 200900018 SPAIN Date of submission of the application: 18.12.2008 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: G01M7 / 02 (2006.01) RELEVANT DOCUMENTS

Category

Documents cited Claims Affected

Y

12.31.2006, B S KIM et al. "The identification of tire induced vehicle interior noise". Applied acoustics 68 (2007) 134-156. Available online 28.08.2006. Recovered from EPOQUE as XP005658631. 1-8

Y

GF LANG and D SNYDER. "Understanding the physics of electrodynamic shaker performance". Sound and Vibration / October 2001. Recovered from the Internet: http://www.dataphysics.com/resources/library-data-physics-center/signalforce.html 1-8

TO

US 4633716 A (MARTIN ROBERT W) 06.01.1987, column 1, line 1 - column 2, line 44. 1-8

TO

PORSCHE. "Additional Experimental Analysis Possibiities for Car Body Structures by Using High Power Electrodynamic Shakers". LMS Conference Europe 2006. Recovered from internet: http://lmsconferences.lmsintl.com 1-8

TO

US 5969256 A (HOBBS GREGG K) 19.10.1999, summary; column 3, line 20 - column 4, line 7. 1-8

TO

US 2007 062293 A1 (LUND DOUGLAS A) 22.03.2007, paragraphs [0009] - [0056]; Figures 1-4. 1-8

TO

US 7464597 B1 (LEE CHI C et al.) 16.12.2008, column 1, line 31 - column 2, line 8; figure 5. 1-8

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 06.30.2011

Examiner B. Weaver Miralles Page 1/5

REPORT OF THE STATE OF THE TECHNIQUE Minimum documentation sought (classification system followed by classification symbols) G01M Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC, WPI, INTERNET  WRITTEN OPINION Date of Completion of Written Opinion: 06.30.2011 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 1-8 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 1-8 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986).  Opinion Base.- This opinion has been made on the basis of the patent application as published.  WRITTEN OPINION 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

B S KIM et al. "The identification of tire induced vehicle interior noise" 12.31.2006

D02

GF LANG and D SNYDER. "Understanding the physics of electrodynamic shaker performance". 01.10.2001

D03

US 4633716 A (MARTIN ROBERT W) 06.01.1987

D04

PORSCHE. "Additional Experimental Analysis Possibiities for Car Body Structures by Using High Power Electrodynamic Shakers". 2006

D05

US 5969256 A (HOBBS GREGG K) 19.10.1999

D06

US 2007 062293 A1 (LUND DOUGLAS A) 03/22/2007

D07

US 7464597 B1 (LEE CHI C et al.) 16.12.2008

2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement Claim 1: Document D01 discloses an anechoic chamber in which elements of a vehicle or a complete vehicle are tested. In said chamber the elements are excited with an electrodynamic vibration equipment to which the device in question is attached (page 144, page 148, figure 15; D01). It differs from the first claim in which it is not disclosed that the vibration equipment is enclosed in a passenger compartment, or that the upper part thereof incorporates holes. The technical effect achieved with both technical elements is to transmit the vibration generated by the electrodynamic system inside the cabin to the device to be tested located outside. The technical problem raised is how to concentrate the vibration on said device by reducing the vibrational discontinuities along the surface of the device to be tested. Document D02 describes the physics of an electrodynamic vibration equipment. On page 4 he describes the isolation considerations that must be taken into account; later on page 8, two figures of said types of equipment are disclosed within an isolation cabin and, in the paragraph on said figures, the possibility of a platform with holes (head expanders, slip table, etc) is described. Thus, the person skilled in the art would use these technical characteristics to solve the technical problem. Therefore, the first claim lacks inventive activity according to article 8.1 of patent law 11/1986. Dependent claims 2-5: The features described in claims 2-4 are disclosed in document D02, since said document discloses that the interface is composed of at least one rigid stud and a fixing mesh. That the fixing mesh has a star shape, seems a mere design option, because it can be designed in multiple ways depending on the object of the test (D02, D05); In addition, the holes have a rigid multi-perforated structure filled with acoustic absorbent material, just as the head expades or slip tables are made: document D03 is cited as an example. Therefore, said claims do not show inventive activity, according to article 8.1 of patent law 11/1986. However, claim 5 has not been found in the prior art, whereby said claim is considered new according to article 6 of patent law 11/1986. Claim 6: Claim 6 refers to the steps of the process to be followed for the acoustic characterization of devices used by the equipment disclosed in the preceding claims. Document D01 uses the same steps of the characterization procedure. In addition, it uses microphones for noise measurement (page 150; D01). While document D02 discloses the equipment characteristics mentioned in claim 1. Therefore, said claim lacks inventive activity, according to article 8.1 of patent law 11/1986. Dependent claims 7-8. Claim 7 is contained in document D02, as in claim 2. Claim 8 is contained in document D01 which discloses that the test sample is a device of a vehicle. Therefore, both claims do not present inventive activity according to article 8.1 of patent law 11/1986.  WRITTEN OPINION Other documents of the prior art: Document D03 discloses an electrodynamic vibration equipment with an upper surface with holes, intended to reduce vibrational discontinuities along the part to be tested (column 2, lines 28-32; D03). Document D04 discloses a test for a car inside an anechoic chamber where an element of the vehicle, such as a wheel, is attached to a frame and in turn to an electrodynamic or shaker vibration equipment. Said shaker is embedded in an unclosed insulated cabin. Document D05 discloses a modular vibration system consisting of three layers: an electrodynamic vibration module, a coupling module and a module that carries the test piece with holes (column 3, line 20 column 4, line 7; D05). Document D06 discloses a vibration testing machine that includes electrodynamic vibration equipment inside a cabin that is not completely closed, with a top cover with holes (Figure 1; D06). Document D07 discloses a system and method for inducing a vibration. The system has an electrodynamic vibration device to which a table with holes is attached and on this a frame in which the piece to be tested is placed (Figure 5; D07).