CAVALLOTTI, Gabriele (Via Cassola di Sotto 83, Castelfranco Emilia, I-41043, IT)
CLAIMS
1) A method for measuring the aerodynamic noise of a vehicle (2); the method comprises the steps of: arranging the vehicle (2) in a measuring station (3) provided with a supporting element (4) which carries at least one blower (7) adapted to generate an air jet towards the vehicle (2); generating the air jet towards the vehicle (2) by means of the blower (7) carried by the supporting element (4) ; displacing, by means of an actuating device (9) , the supporting element (4) with respect to the vehicle (2) from an initial position to a final position; and measuring, by means of at least one phonometer (11), the aerodynamic noise produced by the vehicle (2) struck by the air jet generated by the blower (7) ; the method is characterized in that it comprises the further steps of: detecting the position of the supporting element (4) with respect to the vehicle (2) ; and correlating the aerodynamic noise measurements supplied by the phonometer (11) with the position of the supporting element (4) with respect to the vehicle (2) so that each aerodynamic noise measurement is associated to the position of the supporting element (4) with respect to the vehicle (2) at the time when the aerodynamic noise itself was measured. 2) A method according to claim 1 and comprising the further steps of: setting at least one aerodynamic noise acceptability threshold; comparing the aerodynamic noise measurements supplied by the phonometer (11) with the acceptability threshold; and indicating as anomalies all of the aerodynamic noise measurements which exceed the acceptability threshold.
3 ) A method according to claim 2 , wherein the aerodynamic noise acceptability threshold is variable according to the position of the supporting element (4) with respect to the vehicle (2) . 4) A method according to claim 2, wherein a maximum aerodynamic noise acceptability threshold is set for validating the vehicle (2) and a minimum aerodynamic noise acceptability threshold is set for validating the correct operation of the system (1) for measuring the aerodynamic noise.
5) A method according to one of claims from 1 to 4 and comprising the further step of arranging the phonometer (11) inside the vehicle (2) before starting the measurements . 6) A method according to claim 5, wherein the phonometer (11) comprises two separate right and left microphones (15) for performing a stereophonic measurement of the aerodynamic noise.
7) A method according to claim 5 or 6 and comprising the further step of using an anthropomorphic phonometer (11) comprising an anthropomorphic dummy (13), which is adapted to be rested on a seat of the vehicle (2) and is provided with a head (14) , and a pair of microphones (15) , which are fixed to the head (14) at the position occupied by the ears .
8) A method according to one of claims from 1 to 7 and comprising the step of displacing the supporting element (4) with respect to the vehicle (2) with an intermittent advancement in discrete steps which alternates a step of moving for the transition from a current position to a subsequent position and a step of halting; the measurement of the aerodynamic noise of the vehicle (2) struck by the air jet generated by the blower (7) is performed only during the steps of halting.
9) A method according to one of claims from 1 to 8 and comprising the step of displacing the supporting element (4) with respect to the vehicle (2) with a continuous advancement at a constant speed.
10) A system (1) for measuring the aerodynamic noise of a vehicle (2); the system (1) comprises: a measuring station (3) , which is adapted to receive the vehicle (2) and is provided with a supporting element (4); at least one blower (7) carried by the supporting element (4) and adapted to generate an air jet towards the vehicle (2) ; an actuating device (9) for displacing the supporting element (4) with respect to the vehicle (2) from an initial position to a final position; and at least one phonometer (11) for measuring the aerodynamic noise produced by the vehicle (2) struck by the air jet generated by the blower (7); the system (1) is characterized in that it comprises: a position sensor (10) for detecting the position of the supporting element (4) with respect to the vehicle (2) ; and a processing unit (12) connected to the phonometer (11) and to the position sensor (10) for correlating the aerodynamic noise measurements supplied by the phonometer (11) with the position of the supporting element (4) with respect to the vehicle (2) so that each aerodynamic noise measurement is associated to the position of the supporting element (4) with respect to the vehicle (2) at the time when the aerodynamic noise itself was measured.
11) A system (1) according to claim 10, wherein the phonometer (11) is adapted to be arranged inside the vehicle (2) .
12) A system (1) according to claim 11, wherein the phonometer (11) comprises two separate right and left microphones (15) for performing a stereophonic measurement of the aerodynamic noise.
13) A system (1) according to claim 11 or 12, wherein the phonometer (11) is anthropomorphic and comprises an anthropomorphic dummy (13), which is adapted to be rested on a seat of the vehicle (2) and is provided with a head (14) , and a pair of microphones
(15) , which are fixed to the head (14) at the position occupied by the ears.
14) A system (1) according to one of claims from 10 to 13, wherein the actuating device (9) displaces the supporting element (4) with respect to the vehicle (2) with an intermittent advancement in discrete steps which alternates a step of moving for the transition from a current position to a subsequent position and a step of halting; the measurement of the aerodynamic noise of the vehicle (2) struck by the air jet generated by the blower (7) is performed only during the steps of halting.
15) A system (1) according to one of claims from 10 to 13, wherein the actuating device (9) displaces the supporting element (4) with respect to the vehicle (2) with a continuous advancement. 16) A method for measuring the aerodynamic noise of a vehicle (2); the method comprising the steps of: arranging the vehicle (2) in a measuring station (3) provided with a supporting element (4) carrying at least one blower (7) adapted to generate an air jet towards the vehicle (2); arranging at least one phonometer (11) inside the vehicle (2) ; generating the air jet towards the vehicle (2) by means of the blower (7) carried by the supporting element (4) / displacing, by means of an actuating device (9) , the supporting element (4) with respect to the vehicle (2) from an initial position to a final position; and measuring, by means of the phonometer (11) , the aerodynamic noise produced by the vehicle (2) struck by the air jet generated by the blower (7) ; the method is characterized in that it comprises the further step of using an anthropomorphic phonometer
(11) comprising an anthropomorphic dummy (13), which is adapted to be rested on a seat of the vehicle (2) and is provided with a head (14) , and a pair of microphones (15) , which are fixed to the head (14) at the position occupied by the ears .
17) A method according to claim 16, wherein the phonometer (11) performs a stereophonic measurement of the aerodynamic noise. 18) A system (1) for measuring the aerodynamic noise of a vehicle (2); the system (1) comprises: a measuring station (3), which is adapted to receive the vehicle (2) and is provided with a supporting element (4) ; at least one blower (7) carried by the supporting element (4) and adapted to generate an air jet towards the vehicle (2); an actuating device (9) for displacing the supporting element (4) with respect to the vehicle (2) from an initial position to a final position; and at least one phonometer (11) for measuring the aerodynamic noise produced by the vehicle (2) struck by the air jet generated by trie blower (7) ; the system (1) is characterized in that the phonometer (11) is anthropomorphic and comprises an anthropomorphic dummy (13), which is adapted to be rested on a seat of the vehicle (2) and is provided with
' a head (14), and a pair of microphones (15), which are fixed to the head (14) at the position occupied by the ears.
19) A system (1) according to claim 18, wherein the phonometer (11) comprises two separate right and left microphones (15) for performing a stereophonic measurement of the aerodynamic noise.
20) A phonometer (11) for a system (1) for measuring the aerodynamic noise of a vehicle (2) which is struck by an air jet generated by at least one blower (7) ; the phonometer (11) is characterized in that it comprises : an anthropomorphic dummy (13), which is adapted to be rested on a seat of the vehicle (2) and is provided with a head (14) ; and a pair of microphones (15) , which are fixed to the head (14) at the position occupied by the ears.
21) A phonometer (11) according to claim 19, and comprising two separate right and left microphones (15) for performing a stereophonic measurement of the aerodynamic noise. |
A METHOD AND A SYSTEM FOR MEASURING THE AERODYNAMIC NOISE OF A VEHICLE
TECHNICAL FIELD The present invention relates to a method and to a system for measuring the aerodynamic noise of a vehicle . PRIOR ART
Top-range cars constitute a very small segment of the automotive market and are thus manufactured in limited numbers. Accordingly, top-range cars are assembled on assembly lines with a low degree of automation in which most of the assembly operations are performed manually because the limited number of such cars does not allow an adequate amortization of the costs of a highly automated assembly line. Accordingly, during the assembly of a high-range car, minor errors or assembly inaccuracies may be committed which, when occurring on external parts, may cause the onset of anomalous aerodynamic noise during use. Furthermore, a possible anomalous aerodynamic noise may be acceptable in a low-range car, i.e. in a low-cost car, but is unacceptable and very annoying for the end user in a top-range car, i.e. in a very expensive car. Nowadays, in order to verify that a car is free from anomalous aerodynamic noises, the car is road- tested by an expert test driver who listens for
anomalous aerodynamic noises. However, this inspection is highly subjective and consequently its satisfactory outcome is entirely entrusted to the test driver's ability, it cannot be performed on rainy days because the noise of the rain covers possible anomalous aerodynamic noises, and is very expensive because an expert test driver is employed for a rather long time (the car must reach a significant speed in order to allow the onset of possible anomalous aerodynamic noises) . Furthermore, the test driver who performs the above-mentioned inspection is capable of indicating the presence of an anomalous aerodynamic noise but often is not able to accurately identify the zone of the car which generates such anomalous aerodynamic noise; accordingly, the identification of the zone of the car which generates the anomalous aerodynamic noise to arrange for its repair is long and complicated.
Patent application DE10351792A1 describes a system for monitoring the aerodynamic noise of a car. Such a system comprises a mobile portal, which is provided with a plurality of blowers for generating a plurality of air jets towards a car arranged inside the portal and a conveyor for displacing the gantry with respect to the car; the aerodynamic noise generated by the car which is struck by the air jets blown by the gantry is detected by an operator stationed near the car, either subjectively (i.e. by ear) or objectively
(by means of a portable phonometer handled by the operator him or herself) .
Patent application US2004226379A1 describes a further system for monitoring the aerodynamic noise of a car. Such a system contemplates the use of at least one transportable blower which is manually maneuvered by an operator; the aerodynamic noise generated by the car which is struck by the air jets blown by the portal is detected by an operator stationed near the car, either subjectively (i.e. by ear) or objectively by means of a portable phonometer handled by the operator him or herself •
The systems described in patent applications Dξ10351792A1 and US2004226379Al solve the problem of necessarily conducting a. road test for measuring possible anomalous aerodynamic noises; however, the detections obtained by such systems are strongly affected by the ability of the operator who must be capable of using the portable phonometer correctly because the measurement of a portable phonometer is highly influenced by the position and the orientation of the portable phonometer itself with respect to the car. DESCRIPTION OF THE INVENTION
It is the object of the present invention to provide a method and a system for measuring the aerodynamic noise of a vehicle, which are free from the drawbacks described above and are at the same time easy
and cost-effective to make.
According to the present invention, a method and a system for measuring the aerodynamic noise of a vehicle as claimed in the accompanying claims is provided.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described with reference to the accompanying drawings which illustrate a non-limitative embodiment thereof, in which: • figure 1 is a diagrammatic, side view with parts removed for clarity of a system for measuring the aerodynamic noise of a vehicle made according to the present invention;
• figure 2 is a diagrammatic, front view with parts removed for clarity of the system in figure 1;
• figure 3 is a diagrammatic, plan view with parts removed for clarity of the system in figure 1; and
• figure 4 is a diagrammatic, perspective view of an anthropomorphic phonometer used in the system in figure 1.
PREFERRED EMBODIMENTS OF THE INVENTION
In figure 1, numeral 1 indicates as a whole a system for measuring the aerodynamic noise of a vehicle 2. The system 1 comprises a measuring station 3, which is adapted to receive the vehicle 2 for measuring the aerodynamic noise. The measuring station 3 is provided with a supporting element 4, which is portal-shaped and
comprises two vertical uprights 5 superiorly joined by a horizontal crossbar 6. The supporting element 4 carries three blowers 7 : a central blower 7 fixed to the crossbar 6 and two side blowers 7 fixed to the uprights 5; each blower receives compressed air from a common compressor 8 and is adapted to generate an air jet which is directed towards the vehicle 2 and strikes the vehicle 2 itself.
Furthermore, the system 1 comprises a motorized actuation device 9, which is adapted to longitudinally displace the supporting element 4 with respect to the vehicle 2 arranged in the measuring station 3 from an initial position to a final position. According to the preferred embodiment, shown in the accompanying figures, the vehicle 2 arranged in the measuring station 3 remains static and the actuation device 9 displaces the supporting element 4; alternatively, the supporting element 4 could be maintained static while the actuating device 9 displaces the vehicle 2. A . position sensor 10, which is adapted to detect the position of the supporting element 4 with respect to the vehicle 2, is coupled to the actuating device 9.
Finally, the system 1 comprises at least one phonometer 11 for measuring the aerodynamic noise produced by the vehicle 2 struck by the air jet generated by the blowers 7 and a processing unit 12 connected to the phonometer 11 and to the position
sensor 10 for correlating the aerodynamic noise measurements supplied by the phonometer 11 with the position of the supporting element 4 with respect to the vehicle 2, so that each aerodynamic noise measurement is associated to the position of the supporting element 4 with respect to the vehicle 2 at the time the aerodynamic noise itself is measured.
According to a preferred embodiment shown in the accompanying figures, the phonometer 11 is arranged inside the vehicle 2 on the front driver's seat before starting the measurements and is of the anthropomorphic type; in other words, the phonometer 11 comprises an anthropomorphic dummy 13 , which is adapted to be arranged in a seat of the vehicle 2 and is provided with a head 14, and a pair of microphones 15, ' which are fixed to the head 14 at the position occupied by the ears. Preferably, the anthropomorphic dummy 13 is a so-called w head-torso" , i.e. it presents a lower portion which reproduces the torso of a person and an upper portion which reproduces the head of a person. As the phonometer 11 has two separate microphones 15 (right and left, respectively) , it may carry out a stereophonic measurement of the aerodynamic noise thus distinguishing between the noise received by the right microphone 15 and the noise received from the left microphone 15.
The operation of the system 1 for measuring the aerodynamic noise of a vehicle 2 arranged in the
measuring station 3 is described below.
An acceptability threshold of the aerodynamic noise produced by the vehicle 2 is set before starting the measurement; if the aerodynamic noise produced by the vehicle 2 is maintained below the acceptability threshold during the measurement of the aerodynamic noise, then the vehicle 2 is considered compliant with manufacturing specifications, otherwise the vehicle 2 is identified as faulty and thus in need of a repair intervention. The acceptability threshold of the aerodynamic noise produced by the vehicle 2 is generally identical for the two right and left stereophonic channels, it depends on the speed of the air output by the blowers 7 (the faster the speed of the air output by the blowers 7, the higher the acceptability threshold) and may be either constant or variable according to the position of the supporting element 4 with respect to vehicle 2; in other words, for example, when the air jets generated by the blowers 7 strike the zone of the front hood of the vehicle 2 an aerodynamic noise acceptability threshold value different from that when the air jets generated by the blowers 1 strike the zone of the front doors or the rear hood may be used.
The measurement of the aerodynamic noise of the vehicle 2 arranged in the measuring station 3 contemplates activating the blowers 7 for generating the air jets which strike the vehicle 2 and concurrently
displacing the supporting element 4 with respect to the vehicle 2 from an initial position, in which the element 4 is generally arranged in front of the vehicle 2, to a final position, in which the supporting element 4 is generally arranged behind the vehicle 2, by means of the actuation device 9.
During the displacement of the supporting element 4 with respect to the vehicle 2, the processing unit 12 detects the measurement of aerodynamic noise supplied by the phonometer 11 and measures the position of the supporting element 4 with, respect to the vehicle 2 supplied by the position sensor 1; in this manner, the processing unit 12 may correlate the aerodynamic noise measurements supplied by the phonometer 11 with the position of the supporting element 4 with respect to the vehicle 2 so that each aerodynamic noise measurement is associated to the position of supporting element 4 with respect to the vehicle 2 at the time when the aerodynamic noise itself is measured. In this manner, when an anomalous aerodynamic noise is measured (i.e. a measurement which exceeds the corresponding acceptability threshold) , the processing unit 12 is capable of indicating not only the anomalous measurement, but also the position of the supporting element 4 (i.e. of the blowers 7) with respect to the vehicle 2 at the time when the anomaly was measured and possibly of indicating if the anomalous measurement
occurred at the same time on both stereophonic channels or only on one of the two stereophonic channels . Accordingly, the repairer of the vehicle 2 not only receives the information that the vehicle 2 presents an anomalous aerodynamic noise, but that, for example, the anomalous aerodynamic noise occurred when the blowers 7 were at the front hood zone and only on the right side of the vehicle 2 (i.e. in the right stereophonic channel) ; in this manner, the repairer of the vehicle 2 is greatly assisted in identifying the part of the vehicle 2 on which to intervene.
Preferably, the actuating device 9 displaces the supporting element 4 with respect to the vehicle 2 with an intermittent advancement in discrete steps which alternates a step of moving for the transition from a current position to a subsequent position and a step of halting; the measurement of the aerodynamic noise, produced by the vehicle 2 struck by the air jet generated by the blowers 7 is performed only during the steps of halting. During the steps of moving, the air jets generated by the blowers 7 could be stopped or attenuated to reduce the mechanical stresses to which the supporting element 4 is subjected during the movement. Alternatively, the actuation device 9 could displace the supporting element 4 with respect to the vehicle 2 with a continuous advancement (i.e. without steps of halting) at an either constant or variable
speed (i.e. at a non-null speed which may have an either constant or variable value) .
According to the embodiment shown, the relative displacement between the supporting element 4 and the vehicle 2 occurs in longitudinal direction (i.e. from the front backwards or vice versa) ; however, the relative displacement between the supporting element 4 and the vehicle 2 could also occur in transversal sense (i.e. from left to right, or vice versa) . According to the above, the aerodynamic noise detected by the phonometer 11 is solely compared with a maximum acceptability threshold. Alternatively, the aerodynamic noise detected, by the phonometer 11 could also be compared with a minimum acceptability threshold, which has the sole purpose of allowing a self-test of the correct operation of the system 1; in other words, due to its physical features, when struck by certain air jets generated by the blowers 7, the vehicle 2 inevitably produces a certain noise and if such a noise is not detected by the phonometer 11 then there must be a fault or an incorrect calibration in the system 1.
In the embodiment shown in the accompanying figures, a single anthropomorphic phonometer which is arranged on the front driver's seat, is used; obviously, several anthropomorphic phonometers 11 (not more than 4) variably distributed in the seats of the vehicle 2 could also be used.
The system 1 for measuring the aerodynamic noise presents many advantages, because it is simple and cost- effective to make and, above all, allows to obtain an objective (i.e. not affected and not affectable by the manual ability of operators), automatable, rapid and easily repeatable measurement of the aerodynamic noise produced by a vehicle 2. Furthermore, in case of an anomaly in the aerodynamic noise generated by a vehicle 2, the system 1 is capable not only of indicating the fault, but also of indicating the zone (both longitudinally and transversalIy) of the vehicle 2 which could be responsible for trie anomaly; in this manner, an operator- is greatly assisted in the intervention to eliminate the anomaly. Finally, the fact of using an anthropomorphic phonometer 11 allows to detect the aerodynamic noise produced by a vehicle 2 exactly in the same conditions in which the aerodynamic noise is perceived by the driver and thus allows to detect the possible anomalies which would certainly be perceived by the driver.
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