Classifications

• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K9/00—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers
  • G10K9/12—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated
  • G10K9/13—Devices in which sound is produced by vibrating a diaphragm or analogous element, e.g. fog horns, vehicle hooters or buzzers electrically operated using electromagnetic driving means

Definitions

• the present invention relates to a method for adjusting automotive horns which emit sound by being oscillatorily forced at a prescribed basic frequency.
• a diaphragm is oscillatorily forced by a solenoid as schematically illustrated in Figure 4.
• the horn illustrated in Figure 4 comprises a diaphragm 11, and a solenoid 13 for applying a vibratory force to the diaphragm 11.
• a plunger 13a which is adapted to reciprocate in the solenoid 13, is resiliently urged into engagement with the diaphragm 11, and can be attracted toward a coil 13b of the solenoid 13 by energizing the coil 13b.
• a contact 14 is integrally attached to the plunger 13a to selectively interrupt the supply of electric current to the coil 13b.
• the contact 14 is connected to the +B end of the power supply via a horn switch S W, and energization current is supplied to the coil 13b.
• the contact 14 is disconnected from the +B end of the power supply, and the energization current is stopped.
• An adjust screw 6 is provided for adjusting the limit of the receding movement of the plunger 13a into the solenoid 13.
• the adjustment and test of the horn are conducted at the last stage of the production process.
• a power source and a horn switch are included in the testing system so that the horn may be operated by electrically connecting the power terminals of the horn with the testing system.
• the adjust screw 6 is adjusted while listening to the sound it emits.
• a primary object of the present invention is to provide a method for testing automotive horns which is simple enough to be readily automated.
• a second object of the present invention is to provide a method for testing automotive horns which can complete the test in a short period of time.
• a third object of the present invention is to provide a method for testing automotive horns which can accommodate in variations in the properties of the automotive horns to be tested.
• such objects can be accomplished by providing a method for adjusting the sound which is emitted from an automotive horn, said automotive horn comprising a diaphragm which emits sound by being oscillatorily and repeatedly forced by a plunger in a substantially resonant condition, said plunger being reciprocated by alternating energization and deenergization of a solenoid, a contact which is opened and closed in response to the reciprocating movement of the plunger so as to supply intermittent energization current to the solenoid, and an adjust screw which changes the frequency of the vibratory force of the plunger applied to the diaphragm by restricting the reciprocating movement of the plunger, characterized by the steps of: defining a prescribed range of electric current which is previously determined to achieve an acceptable sound emission from the automotive horn; turning the adjust screw by a prescribed angle with a motor actuator; detecting electric current supplied to the solenoid after turning the adjust screw by the prescribed angle; determining if the electric current is within the prescribed range or not;
• an automotive horn which can be adjusted for proper sound emission by tuning the oscillatory frequency of the reciprocating movement of the plunger to the resonant frequency of the diaphragm by adjusting the stroke of the plunger, because changing the stroke of the plunger changes the number of the closure of the contact per unit time period and thereby changes the energization current, it is possible to associate the frequency of the plunger movement or the frequency of the vibratory force applied to the diaphragm with the energization current. Therefore, by turning the adjust screw while detecting the energization current until the energization current reaches a value corresponding to the design frequency of the plunger, it is possible to adjust and test the horn in a simple and economical fashion.
• the angle by which the adjust screw is turned at each attempt may be selected as a relatively large value.
• Figure 1 is diagram showing the outline of the adjusting system for an automotive horn to which the present invention is applied;
• Figure 2 is a flow chart showing the procedure of adjusting the automotive horn according to the present invention.
• Figure 3 is a graph showing the procedure of adjusting the automotive horn according to the present invention.
• Figure 4 is a diagram showing the structure of a conventional automotive horn. BEST MODE FOR CARRYING OUT THE INVENTION
• FIG 1 is a diagram showing the overall structure of a testing system for testing sound emitters to which the present invention is applied.
• the automotive horn 1 given as an example of the subject of the testing system is identical to that of the prior art example, and the description of its structure is therefore omitted.
• sound emitted from the hom 1 is captured by a microphone 2, and the signal from the microphone 2 is supplied to an FFT spectrum analyzer 4 via a sound level meter 3.
• the spectrum signal from the FFT spectrum analyzer 4 is supplied to a computer 5.
• the system further includes a motor actuator 7 consisting of a servo motor equipped with a screwdriver bit for turning an adjust screw 6 of the hom 1, and a servo motor driver 8 which receives a control signal from the computer 5 to control the motor actuator 7.
• a voltage control signal from the computer 5 is supplied to a DC power source 9 which supplies a DC voltage to the hom 1 to thereby cause a diaphragm of the hom 1 to oscillate and emit sound in the same manner as the prior structure described previously.
• a current detector 12 is provided on the power line leading from the DC power source 9 to the hom 1, and a current detection signal from the current detector 12 is supplied to the computer 5.
• the frequency of the oscillatory force of the plunger of the solenoid which is applied to the diaphragm in the automotive hom 1 is tuned to the basic resonant frequency of the diaphragm.
• a sound according to the design (sufficient sound pressure and favorable tones) is produced by driving the diaphragm at its basic resonant frequency.
• each of the homs 1 which is subjected to the test of the present invention is assembled so as to define a highly narrow gap in its contact.
• the horn 1 is placed as illustrated in Figure 1 with the power line of the power source 9 connected to the hom 1, and is adapted to be actuated by a drive voltage regulated by the computer 5.
• An initial rotational angle and speed for the motor actuator 7 are defined in step STl, and the servo motor driver 8 receives a rotational start signal from the computer 5 so that the motor actuator 7 actually turns the adjust screw 6 with the screwdriver bit 7 in the direction to widen the gap of the contact 14 in step ST2.
• the initial rotational angle for the adjust screw is selected as a relatively large angle which is empirically determined so as to reach a region immediately before the prescribed range of electric current.
• the computer 5 sets a timer for delaying the operation of the current detector 12 in step ST3.
• step ST4 the current detector 12 detects the electric current, and supplies a detected current value to the computer 5 via an AD converter.
• step ST5 it is determined if the electric current I is less than an upper limit I ⁇ of a prescribed range. If so, the program flow advances to step ST6 where the motor actuator 7 is stopped.
• step ST7 If the electric current is detected to be greater than the upper limit or outside the prescribed range in step ST5, the program flow advances to step ST7.
• the electric current does not change within a prescribed time limit which is defined by a timer not shown in the drawing, as it is possible that the plunger 13a or the contacts 14 are not properly adjusted, the testing process is discontinued, and the hom 1 is rejected
• step ST7 a new control value (rotational angle and rotational speed) for the motor actuator 7 is defined according to the difference between the detected current value and a reference value in the prescribed range.
• step ST8 a drive start signal is supplied to the servo motor driver 8. If the motor actuator 7 is rotating, it is allowed to continue rotating. If the motor actuator 7 is stationary, it is allowed to start rotating.
• step ST9 a timer is set so as to define a time delay which depends on the difference between the detected current value and the reference value (time required for reaching a rotational speed corresponding to the reference value), and the program flow retums to step ST4 upon the time-up of this timer.
• step ST10 When the program flow has advanced from step ST5 to ST6, it is determined in step ST10 if the electric current I is greater than the lower limit I L of the prescribed range as illustrated in Figure 3. If the electric current fell below the lower limit or if the adjust screw 6 was turned by too large an angle, the program flow advances to step ST12. If the electric current is greater than the lower limit, and is therefore within the prescribed range, the program flow advances to step ST11.
• This control value can be such that the adjustment screw can be turned until the current value goes over the upper limit of the prescribed range (toward the initial state).
• a reverse rotation signal is supplied to the motor actuator 7 by using the control value of step ST15.
• a delay time according to the control value is set on a timer. When the timer has timed up, the program flow advances to step STl 8 where the rotation of the motor actuator 7 is stopped and the program flow retums to step ST4.
• the program flow has passed through steps ST14 to ST18, as the detected current value is greater than the upper limit, the program flow advances from step ST5 to ST7, and the adjust screw 6 is again adjusted from the direction of the initial condition.
• the tendency illustrated in Figure 3 may be demonstrated at a certain adjusted position of the adjust screw 6.
• the horn A indicated by the solid line demonstrates a peak of the electric current substantially centrally in the prescribed range of the current, and the sound property can be determined to be acceptable by supplying electric current of the reference value.
• the hom B indicated by the one-dot chain line can be found acceptable with respect to its sound property by an electric current value near the lower limit of the prescribed range while the hom C indicated by the two-dot chain line can be found acceptable with respect to its sound property by an electric current value near the upper limit of the prescribed range. Because of such fluctuations in the properties of the homs to be tested, it is desirable to put the adjust screw 6 to an initial condition before starting the adjustment with a new control value.
• step ST11 When the program flow has advanced from step ST10 to STH, the sound signal is sampled and analyzed by the FFT spectrum analyzer in step ST11.
• the criteria for this analysis may include the sound pressure, the frequency of maximum sound pressure, and the comb-shaped frequency pattem of the spectral sound data, when an efficient resonance condition is sought, and the final determination is made by quantitatively evaluating the property values of these criteria.
• step STl 9 the test results are evaluated, and the program flow advances to step ST20 when the test results are acceptable and to step 12 when the test results are not acceptable.
• the test process is concluded.
• the frequency of the plunger movement which dictates the property of the emitted sound is associated with the energization current so that a quantitative evaluation of the sound may be made.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
• Apparatuses For Generation Of Mechanical Vibrations (AREA)
• Control Of Motors That Do Not Use Commutators (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=16931730

Family Applications (1)

Country Status (3)

Cited By (3)

Citations (5)

• 1995
  • 1995-08-17 JP JP23195895A patent/JP3309037B2/ja not_active Expired - Fee Related
• 1996
  • 1996-08-09 MX MX9801207A patent/MX9801207A/es unknown
  • 1996-08-09 WO PCT/JP1996/002269 patent/WO1997007495A1/en active Application Filing

Patent Citations (5)

Non-Patent Citations (1)

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