Measuring and testing – Testing impact delivering device
Reexamination Certificate
2003-01-29
2004-06-01
Lefkowitz, Edward (Department: 2855)
Measuring and testing
Testing impact delivering device
C073S011030, C073S011040, C073S011050, C073S012010, C074S005400, C074S005500, C188S378000
Reexamination Certificate
active
06742381
ABSTRACT:
INCORPORATED BY REFERENCE
The disclosure of Japanese Patent Application No. 2002-067454 filed on Mar. 12, 2002 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and a method for evaluating damping performance or capability of vibration-damping devices, and to a testing method using the apparatus.
2. Description of the Related Art
A variety of vibration-damping devices using elastic members or the like have been employed or proposed in order to reduce vibration excited in apparatus and equipments of various kinds in which vibration would raise problems. The proposed vibration-damping devices have a variety of constructions including a so-called dynamic damper as disclosed in JP-A-8-193642 and a vibration-damping device as disclosed in WO00/14429, which are arranged in order to reduce vibrations and noises within the vehicle caused by oscillation force transmitted from a power unit, tires, and the like.
The dynamic damper taught by JP-A-8-193642, the vibration-damping device disclosed in WO00/14429, and similar devices may not always effectively exhibit the desired damping performance, due to deviation in factors such as component dimensions, materials and mass.
To ensure that final products consistently exhibit required damping performance, it is desirable to subject vibration-damping devices to performance evaluation testing prior to shipment. Specific examples of testing methods include, for example, (a) sweep oscillation methods, which involve subjecting the vibration-damping device to vibrational load at gradually varied frequency with an electromagnetic vibrator while measuring vibrational input/output characteristics in terms of phase angle, gain etc; and (b) hammering methods, which involve measuring vibrational characteristics including resonance frequency or other intrinsic values, while subjecting the vibration-damping device to impact force.
The former one, (a) sweep oscillation methods, have the disadvantage of high cost of testing equipment per se, as well of requiring some time for the vibration mode of the vibration-damping device to stabilize so that the total time required for a single test cycle, including installation and removal of the vibration-damping device in and from the testing device, can be as long as 120 seconds. For this reason, the sweep oscillating methods are impractical where all or virtually all of the final product units are to be tested. The latter case, (b) hammering methods, on the other hand, while affording shorter measuring times than sweep methods, have the drawback that due to the extreme difficulty of consistently controlling parameters such as the magnitude and direction of the impact force during measurement, the benchmark for evaluating damping performance is not always precise vis-á-vis the actual measurements obtained, so that these measurements can only be used as a general guide.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a novel damping performance evaluation apparatus and damping performance evaluation method for vibration-damping devices whereby damping performance of vibration-damping devices can be measured quickly and with high accuracy, and a novel testing method for vibration-damping devices, which employs the vibration performance evaluation apparatus.
The above and/or other objects may be attained according to at least one of the following modes of the invention. Each of these modes of the invention is numbered like the appended claims and depending from the other mode or modes, where appropriate, to indicate possible combinations of elements or technical features of the invention. It is to be understood that the following modes or elements of the invention may be adopted at any possible optional combinations, and that the present invention is not limited to the following modes or combinations of these modes, but may otherwise be recognized based on the thought of the present invention that described in the whole specification and drawings or that may be recognized by those skilled in the art in the light of the disclosure in the whole specification and drawings.
(1) A damping performance evaluation apparatus for vibration-damping devices comprises: (a) a support member for detachably supporting a vibration-damping device in a state enabling the vibration-damping device to exhibit a damping effect thereof; (b) a hammer member for applying oscillation force to the vibration-damping device, caused by means of gravitational action to descent to strike directly or indirectly the vibration-damping device supported by the support member; (c) a double-strike preventing member for preventing the hammer member from dropping a second time due to rebound after initially striking the vibration-damping device, so as to prevent double-strike of the vibration-damping device by the hammer member; (d) a vibration sensor installed at a vibration zone caused to vibrate through oscillation force applied by the hammer member, for outputting an electrical signal in response to vibration at the vibration zone; and (e) a sensing member for sensing a vibration mode in the vibration zone on the basis of an output of the vibration sensor.
The damping performance evaluation apparatus constructed according to this mode of the invention is designed to allow damping performance of the vibration-damping device to be evaluated by applying oscillation force to the vibration-damping device while supported in the state enabling the device to exhibit damping effect. This is accomplished by causing the hammer member to undergo gravitational descent and strike the vibration-damping device directly or indirectly, and then measuring, by means of the vibration sensor and the sensing member, the vibration mode in the vibration zone caused to vibrate through oscillation force applied by the hammer member.
By means of the double-strike preventing member, the hammer member is prevented from dropping the second time due to rebound after initially striking the vibration-damping device, thus preventing double-strike of the vibration-damping device by the hammer member. This permits the vibration-damping device to be subjected to one cycle of a given level of initial oscillation force through gravitational action. Thus, in the initial stage of vibration, the vibration zone can be impacted consistently with oscillation force of constant magnitude and directionality, so as to provide uniform conditions for measurement over multiple tests. Measurements for a number of vibration-damping devices can thus be evaluated on the basis of a consistent benchmark, making it possible to judge damping performance satisfactory or unsatisfactory with a high degree of accuracy.
As a general principle, a single application of oscillation force through gravitational action to the vibration-damping device is enough to complete the measuring procedure, thereby allowing the vibration mode in the vibration zone to be measured quickly, so that testing of all vibration-damping device units prior to shipment, for example, is now viable.
A variety of know sensors those employing a piezoelectric element to output an electrical signal may be preferably employed as the vibration sensor in the present mode, for example. The sensing member may be suitably designed depending upon items of damping performance being evaluated, using, for example, an analog or digital level recorder, band pass filter, tracking filter, frequency analysis device, or the like. Preferably, a frequency analyzer employing a Fast Fourier Transform (FFT) is employed, for the sake of rapidity of measurement and ease of modifying measurement settings.
(2) A damping performance evaluation apparatus according to the above mode (1) further comprises hammer supporting mechanism for supporting the hammer member at a predetermined height, and for releasing the hammer member so as to allow the hammer member to descend under the gravitationa
Bever Weaver & Thomas LLP
Ellington Alandra
Lefkowitz Edward
Tokai Rubber Industries Ltd.
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