Patent Application
20090305796
None.
1. Field of the Invention
The subject matter disclosed herein relates to a crankshaft assembly for a reciprocating internal combustion engine having a crankshaft position encoder which is mounted upon either a crankshaft output flange, or at the front of the crankshaft.
2. Discussion of Prior Art
Reciprocating internal combustion engines, particularly those employed in automotive vehicles, utilize a crankshaft having an output flange to which a flywheel or flex plate is fastened. The friction necessary to transmit torque between the engine's crankshaft and the flywheel is produced at least in part by clamping the flywheel to the output flange by means of threaded fasteners. Unfortunately, as engine output torques have increased, sometimes without a concomitant increase in the engine size, and often through the use power adders such as charge boosters, it has become increasingly difficult to transmit engine torques efficiently. Moreover, if a flywheel or flexplate begins to slip or shift upon a crankshaft, the resulting vibration, while annoying, is only a telltale of far greater problems, because rapid engine destruction may ensue. Although it is known to insert a friction-enhancing washer between a flywheel and a crankshaft output flange, this type of structure is problematic because the washer may be omitted inadvertently during the assembly process, with the result that the engine will likely fail due to slippage of the flywheel with respect to the crankshaft.
Most automotive engines utilize a crankshaft pulley, mounted at the end of the crankshaft opposite the flywheel or flexplate end. Depending upon the particular application, such crankshaft pulleys usually drive a number of accessories, such as a generator, water pump, air conditioning compressor, power steering pump, and others. This duty necessitates a high torque capacity joint between the crankshaft pulley and the crankshaft. While it is known to handle this torque requirement, at least in part, by a key inserted into a keyway defined by slots formed in the crank damper's hub and the crankshaft's pulley mounting surface. This arrangement is not entirely satisfactory, because the majority of the torque load is accommodated by the joint defined by the crankshaft damper bore and the crankshaft's snout. Unfortunately, higher torque operation requires a concomitant increase in the size of the joint, which is sometimes difficult to provide because there is insufficient space to package the joint.
It would be desirable to provide a crankshaft assembly with a friction-enhancing component interposed between the crankshaft and the flywheel or crankshaft pulley, wherein the introduced component is essential to the operation of the engine, to the extent that absence of the component will prevent the engine from operating. This will assure that the higher torque capacity provided by the friction enhancing component is always present during operation of the engine.
According to an aspect of the present invention, an internal combustion engine crankshaft assembly includes a crankshaft having an output flange, a flywheel fastened to the output flange, and a sensor wheel positioned between the output flange and the flywheel, with the sensor wheel including a generally planar base having a first side in contact with the output flange, and a second side in contact with the flywheel. An integral ring-shaped sensor element circumscribes the generally planar base of the sensor wheel. A pressure-responsive friction-promoting material is applied to both of the first side and the second side of the sensor wheel, whereby the flywheel is torsionally locked with respect to the crankshaft flange.
According to another aspect of the present invention, the generally planar base of the sensor wheel is configured as an annulus having a pilot bore which is engaged with a pilot formed on the crankshaft.
According to another aspect of the present invention, the friction-promoting material applied to the sensor wheel may include a mineral based particulate, or a crystalline diamond composition.
According to yet another aspect of the present invention, the sensor wheel may include a toothed encoder wheel which functions as a crankshaft position encoder wheel.
According to yet another aspect of the present invention, an electronic engine control device may be positioned between the output flange of a crankshaft and a flywheel, with friction promoting material being applied to both the crankshaft and the flywheel sides of the engine control device.
It is an advantage of the present invention that an engine will have increased torque transmitting capability between the engine's crankshaft and the flywheel, which is assured because of the use of an engine control device which must be in place for the engine to operate at all.
It is another advantage of a system according to the present invention that enhanced torque transmitting capability is established between an engine crankshaft and flywheel without the cost of additional components.
It is another advantage of a system according to the present invention that enhanced torque transmitting capability is achievable without increasing the size of crankshaft, flywheel, and crankshaft damper components.
It is another advantage of a system according to the present invention that enhanced torque transmitting capability is achievable with spark ignition, compression ignition and homogeneous charge compression ignition internal combustion engines.
Other advantages, as well as features of the present invention, will become apparent to the reader of this specification.
As shown in
Details of sensor wheel 38, which comes from a class of control devices such as rotary position encoder wheels which are mountable upon an engine crankshaft, are shown in specificity in
As shown in
Those skilled in the art will appreciate in view of this disclosure that other compositions, such as, without limitation, mineral-based particulates, sometimes configured as abrasive compositions, may be used as a pressure-responsive, friction-promoting material in the present system.
The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention. Accordingly the scope of legal protection afforded this invention can only be determined by studying the following claims.
