Measuring and testing – Simulating operating condition – Marine
Reexamination Certificate
1998-06-29
2002-05-21
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Simulating operating condition
Marine
Reexamination Certificate
active
06389888
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to systems for testing electrical and mechanical energy transfer systems that exhibit vibratory and other responses to electrical or mechanical input energy, and more particularly, to an arrangement that isolates a mechanical or electrical system under test and produces signals and data corresponding to a plurality of operating characteristics of the system under test in response to the input energy.
2. Description of the Related Art
Noise testing of gears to date has been attempted by methods that rigidly mount the gear or axle assemblies in one or more planes. Some other previous attempts chose to have one of the rigidly mounted planes resonate at a frequency sympathetic to gear noise. None of these methods, or any other rigidly mounted test system has been successful. This is due to the lack of repeatability of the previous systems, largely as a result of interacting resonances, and external background noise that is transferred through the rigid mounting system. This is especially true in a production test environment.
These deficiencies in the prior art are most evident in the axle industry. At this time, the only widely accepted way of measuring gear noise is to acquire an assembled axle and install it in a test car. A specially trained individual then drives the car over its typical operating range while carefully listening for axle gear noise. The individual rates the quality of axle gear noise on a scale that is typically 0 to 10. Ten is usually a perfect axle, i.e. one that has no gear noise. This method is made difficult by:
1 The lack of available trained noise rating individuals
2 The cost of test cars.
3 The lack of quality roads or test tracks on which to perform a repeatable and accurate test.
4 The time required for each test.
5 The subjectivity that humans bring into the rating system.
Typically less than a dozen axles can be tested by a major manufacturer in one shift due to all of the above complications. This low number is not statistically valid when it is considered that most manufacturers make thousands of axles each day. Even with all of the above problems, human testers in cars are the only widely accepted method of axle testing in the industry due to the lack of a better more reliable testing method. This lack of a scientific basis for rating axles and gear systems is made worse when the reader considers that modem cars are extremely quiet, and are evolving to become more quite. This market direction increases the pressure on axle and other gear manufacturers to make their products quieter. There is a need for a system that offers gear and axle manufacturers a repeatable, reliable, accurate and practical way of measuring gear noise in production or laboratory environments.
It is, therefore, an object of this invention to provide a system for testing an energy transfer system, such as a vehicle axle, quickly and inexpensively, and achieving repeatable results.
It is often desired in the testing of a differential gear train system to determine the qualitative characteristics of the engagement between the pinion and ring gears, excluding any gear engagement noises produced by the differential gear set. This would require both rotatory outputs to be driven at precisely the same speed, in order that the differential gear set not become active. Noise from the engagement between the members of the differential gear set will interfere with the qualitative determination of the noise being issued by the engagement between the pinion and ring gears, and is generally not otherwise sufficiently objectionable to warrant specific testing therefor, as it occurs usually only at slow vehicle speeds during turns.
The foregoing notwithstanding, it is expensive and complicated to test a differential axle system in a manner that excludes the noise of engagement of the members of the differential gear set, as precisely controlled loads are required at each axle output. During performance of such a test in a production environment, generally two people are required, one at each output, in order to achieve the testing throughput needed during production.
It is, therefore, another object of this invention to provide a testing arrangement and method for a differential axle system that permits rapid and effective testing of the engagement between the pinion and ring gears, without interference from the differential gear set.
SUMMARY OF THE INVENTION
In accordance with a further apparatus aspect of the invention, there is provided an arrangement for isolating a mechanical drive system for a vehicle while it is subjected to a testing process, the drive system being of the type having a rotatory input, at least two rotatory outputs, and a differential gear set arranged on a differential gear set shaft. In accordance with the invention, the arrangement is provided with a base for supporting the arrangement and the mechanical drive system. An isolation support supports the mechanical drive system whereby the mechanical drive system is translatable in at least one plane of freedom with respect to the base. In addition, a rotatory drive applies a rotatory drive force to the mechanical drive system, and a first drive coupler transmits a torque from the rotatory drive to the rotatory input of the mechanical drive system. A rotatory load is provided to apply a rotatory load force to the mechanical system. A second drive coupler transmits and receives torque from the rotatory load means to the differential gear set shaft of the mechanical drive system.
In one embodiment of the invention, the second drive coupler is provided with a load shaft having a load shaft termination for entering the mechanical drive system and engaging with the differential gear set shaft. The load shaft termination is provided with a fork-like termination distal from the rotatory load, the fork-like termination having first and second axially parallel protuberances, whereby the differential gear set shaft is accommodated therebetween during the engagement.
There is further provided an engagement arrangement for securing the mechanical drive system to the isolation support, the engagement arrangement having a first position with respect to the base wherein the mechanical drive system is installable on, and removable from, the isolation support, and a second position wherein the mechanical drive system is secured to the isolation support.
An engagement driver is coupled to the base and to the engagement arrangement for urging the engagement arrangement between the first and second positions, the engagement arrangement being coupled to the engagement driver when the engagement arrangement is in the first position, and isolated from the engagement driver when the engagement arrangement is in the second position.
In further embodiment of the invention, the mechanical drive system has forward and reverse directions of operation, and drive and coast modes of operation for each of the forward and reverse directions of operation. The mechanical drive system contains at least a pair of meshed elements, at least one of the pair of meshed elements being a gear having a plurality of gear teeth thereon, the gear teeth each having first and second gear tooth surfaces for communicating with the other element of the pair of meshed elements, a mechanical energy transfer communication between the pair of meshed elements being effected primarily via the respective first gear tooth surfaces during forward-drive and reverse-coast modes of operation, and primarily via the respective second gear tooth surfaces during forward-coast and reverse-drive modes of operation. In a practical embodiment of the invention, the pair of meshed elements is provided with a pinion gear and a ring gear.
A first acoustic sensor is arranged at a first location in the vicinity of the mechanical drive system for producing a first signal responsive substantially to a qualitative condition of the meshed engagement between the pinion gear and the ring gear. The qualitative con
Juranitch James C.
Olschefski Robert D.
Davis Octavia
Fuller Benjamin R.
Rohm & Monsanto, PLC
Veri-Tek Inc.
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