Data processing: structural design – modeling – simulation – and em – Simulating nonelectrical device or system – Mechanical
Reexamination Certificate
1999-02-12
2002-06-04
Choi, Kyle J. (Department: 2163)
Data processing: structural design, modeling, simulation, and em
Simulating nonelectrical device or system
Mechanical
C702S034000, C073S007000, C073S009000
Reexamination Certificate
active
06401058
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to systems for simulating wear conditions, and more particularly, to an arrangement and method of simulating friction environments, such as the friction conditions between components of an internal combustion engine.
2. Description of the Related Art
A significant portion of engine power within an internal combustion engine is lost as result of friction between the piston ring(s) and cylinder bore(s). There is need in the field of engine manufacture for a system that characterizes the frictional and wear characteristics of existing and new materials, so that their suitability for application within the various components of engines can be determined. Most commonly, gray iron is used as the cylinder bore material. This material is characterized as having good wear resistance due to hard carbide particles within it, but also a measure of lubricity is achieved by the graphite flakes contained therewithin which behave as a solid lubricant. Thus, the tribological properties of iron has resulted in cast iron liners being pressed or cast into aluminum engine blocks.
Aluminum alloys, thermal spray coated cylinder liners, and powder metal composites that contain solid lubricants have shown promising characteristics that may render these materials suitable as future cylinder bore material. However, extensive experimentation is required to understand the physical mechanisms of friction in cylinder liner-piston ring frictional contact.
Conventional friction and wear testing systems may include a pin on a disk, or block on a ring for testing. It is a problem with these known arrangements that they cannot simulate the operating conditions within an internal combustion engine. In fact, these known arrangements cannot produce reciprocating motion that would simulate the piston ring/cylinder wall interface in an internal combustion engine. The microstructure of a thermal spray coating that has been sprayed directly on to flat plates or rings is not representative of the microstructures obtained by spraying directly onto the cylinder gold liner surface. Thus, the use of actual engine components is highly desirable when simulating the friction environment in an engine, in order to maintain the actual geometry of the surface as well as its texture and microstructure.
It is a problem with known arrangements that test actual engines that they are expensive and their use is quite time consuming. Additionally, extensive modification of engine components is required. Gas and inertia forces are large compared to friction forces, and the temperature, load, and lubricant rate cannot be maintained constant during operation. It is additionally desired to distinguish the friction forces that result from the compression rings, from those that result from the oil ring, the piston skirt, and the bearings.
Current bench test systems have either very small stroke length and contact area, or low running speeds, which do not result in a close simulation of the actual engine conditions. There is, therefore, a need for an arrangement and a method of simulating frictional environments, that yield test results that are representative of the desired environment, such as the interior of an internal combustion engine, and which are repeatable to facilitate evaluation of advanced materials and lubricants.
The prior art has endeavored to produce wear testing systems that employ reciprocating motion. In one such system, an entire piston ring is positioned in a disk shaped holder, and the installed ring is reciprocated between static liner segments using a short stroke, on the order of one inch. This permits only small liner samples to be tested, two at a time. It is a problem with this known arrangement that its use limited to a short stroke at a relatively low running speed due to unbalanced inertia forces. It is a further problem that the disk-shaped holder that holds the complete piston ring is not representative of an actual piston. Still another problem with this known arrangement is that it is incapable of achieving simulation of various lubrication regimes.
It is, therefore, an object of this invention to provide a friction and wear simulation system that can be installed on a laboratory bench.
It is another object of this invention to provide a wear and friction simulation system that closely approximates a conditions encountered within an internal combustion engine.
It is also an object of the is invention to provide a friction and wear simulation system that can be operated at high speeds.
It is a further object of this invention to provide a wear and friction simulation system that allows a reciprocating stroke length corresponding to that of an actual internal combustion engine.
It is additionally an object of this invention to provide a wear and friction simulation system that enables testing at a plurality of lubricant delivery regimes.
SUMMARY OF THE INVENTION
The foregoing and other objects are achieved with this invention which provides, in a first apparatus aspect thereof, a system for simulating a friction environment between first and second wear elements in frictional communication with one another. In accordance with the invention, a first support arrangement supports the first wear element, and a reciprocating drive arrangement drives the first support arrangement reciprocatingly along the substantially axial path of reciprocation. A dynamic counterbalance arrangement is coupled to the reciprocating drive arrangement, and serves to nullify second order harmonic mechanical energy. A rotatory drive coupler is coupled to both, the reciprocating drive arrangement and the dynamic counterbalance arrangement. The rotatory drive coupler receives rotatory drive from a motor. A second support arrangement is provided for supporting the second wear element. A linear drive is coupled to the second support arrangement and urges same in the direction that is transverse to the substantially axial path of reciprocation. An electrical force signal responsive to a force applied by the linear drive to the second support arrangement is produced by a force gauge that is coupled to the linear drive.
In one embodiment of the invention, the second support arrangement is arranged to enable a transverse displacement of the second wear element with respect to the frictional communication with a first wear element. Thus, in embodiments of the invention where the second wear element is a portion of a piston ring, the ring portion is enabled to travel circumferentially for a limited distance within a groove that accommodates same within the second support arrangement. The second support arrangement may be, in certain embodiments, a portion of an actual piston of an internal combustion engine.
In another embodiment of the invention, the second support arrangement enables a transverse displacement of the second wear element with respect to the frictional communication with the first wear element. Again, in an embodiment of the invention where the second wear element is a portion of a piston ring on an internal combustion engine, the ring is permitted to tilt within the groove that accommodates same within the second support arrangement. Also, as stated, the second support arrangement in this embodiment of the invention may be a portion of a piston of an internal combustion engine.
In a further embodiment a rotational encoder produces and electrical signal that contains rotatory information relating to a rotational position of the rotatory drive coupling arrangement. In this manner, a signal is generated that permits instantaneous identification of the angular position of the rotatory drive coupler, and correspondingly, the first support arrangement. In an advantageous embodiment of the invention, the rotatory information contained within the electrical signal produced by the rotational encoder is correlated against the electrical force signal produced by the force gauge, whereby information in the form of a graphical representation can be provided
Akalin Ozgen
Newaz Golam M.
Choi Kyle J.
Rohm & Monsanto, P.L.C.
Wayne State University
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