Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1991-07-11
1992-09-08
Cross, E. Rollins
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9017, 123 9031, F01L 134
Patent
active
051449200
DESCRIPTION:
BRIEF SUMMARY
As the title indicates, this invention concerns an automatic governor, for internal combustion engines, that regulates the stroke between the crankshaft and the camshafts by means of actuators placed to operate on the chain connecting said crank and camshafts.
Internal combustion engines, as is known, use fuel that becomes consumed within the mass of active fluid. To transform thermal energy into mechanical energy it is essential to have what are known as crankshafts with pistons sliding in their cylinders, and valves for feeding in the fuel and discharging the products of combustion. These valves are operated by a camshaft according to a combination of factors defining the instants in which said valves open and close in relation to the position of the crankshaft. This combination of factors is expressed in the word "timing".
Timing means that precise stage of the operation when the crankshaft and the camshaft are situated in a radial position, in relation to each other, that will obtain maximum performance from the engine.
Said performance depends on variables, such as: stroke begins; T. D. C.;
It is further known that optimum timing values differ according to whether engine running speed is high or low.
All the above emphasises the need to have details of timing set in the best possible way and to keep them so set.
In present engines mechanical connection between crankshaft and camshaft is usually made by means of a chain or toothed belt and by pinions or gear wheels.
Connection between crankshaft and camshaft, or shafts, by chains or belts inevitably involves more or less considerable departure from the above mentioned optimum values due to mechanical tolerances of the various parts, and to wear and warping due to heat, stresses, high speeds and changes of regime.
The above invention eliminates these drawbacks and further offers important advantages as will be explained below.
DESCRIPTION OF THE INVENTION
Subject of the invention is a governor, for internal combustion engines, of the stroke between crankshaft and camshafts connected by a belt or continuous chain of some kind, that determines, by means of actuators, the variation in length of sections of chain between the crankshaft and camshafts, or between the latter, without varying the total length of said chain.
It thus becomes possible: variations due to changes of temperature and to the stresses set up by movement; running speed.
An automatic tightener, acting on a section of chain, keeps constant the tension of said section, from one moment to the next, adjusting the effect of the actuators on the other sections of chain.
Each actuator operates on a section of chain through a cam. The various positions taken up by said cam obviously correspond to a longer or shorter length of said section of chain.
In a preferred type of execution the actuators function by means of an electric motor. Based on data received from appropriate detecting devices an electronic drive unit evaluates, from one moment to the next, the positions of the crankshaft in relation to the camshafts, and puts into operation the actuator motors which then restore, or produce, optimum timing.
Similarly, a program is inserted in an electronic drive unit which, using information received from an appropriate detecting device when engine speeds change, can control the actuators to secure optimum timing for each running speed.
In one type of execution the detectors consist of sensors mounted onto the fixed structure of the engine on the circular trajectories followed by signalling devices, such as permanent magnets for example, fixed at a certain radial point of the crankshaft and camshafts.
The invented governor can be used both on engines with a single camshaft and on those with two or more camshafts, timing of either type of these shafts being possible by mounting an actuator for each one.
There are obvious advantages attached to this invention. Any accidental variations occurring in the positions of camshafts in relation to crankshafts, compared with those scheduled, is automatical
REFERENCES:
patent: 3496918 (1970-02-01), Finlay
patent: 3888217 (1975-05-01), Hisserich
patent: 4484543 (1984-11-01), Maxey
patent: 4715333 (1987-12-01), Oyaizu
patent: 4744338 (1988-05-01), Sapienza, IV
patent: 4862845 (1989-09-01), Butterfield et al.
patent: 4872426 (1989-10-01), Sapienza, IV
Cross E. Rollins
Lo Weilun
Striker Michael J.
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