US 3533382 A
Description (OCR text may contain errors)
United States Patent 1 Luis N. Bonello Conesa 3986, Buenos Aires City, Argentina 764,227
Oct. 1, 1968 Oct. 13, 1970 4 Inventor Appl. No. Filed Patented INTERNAL COMBUSTION ENGINES TAPPET ASSEMBLY FOR INCREASING VALVE LIFT 3 Claims, 4 Drawing Figs.
U.S. Cl 123/90.61, 74/55, 74/569. 123/9048 lnt.Cl F011 1/14, F16h 53/06 Field of Search 123/90; 74/569. 55
I References Cited UNITED STATES PATENTS 7/1921 Edloff 11/1924 Falwell Bergmann et a1 Primary Examiner-Al Lawrence Smith Att0rneyMichael S. Striker INTERNAL COMBUSTION ENGINES TAPI'ET ASSEMBLY FOR INCREASING VALVE LIFT This invention relates to certain improvements provided in internal combustion engines, and more particularly to the valve command elements in four stroke engines.
It is of common knowledge that one of the efficiency factors in engines of this type lies in the volume of fuel mixture entering the cylinder during the admission cycle as well as'the amount of burnt gases that are eliminated from the combustion chamber during the exhaust cycle. The ideal situation is to obtain maximum indexes for both circumstances but, naturally, this is never fully achieved.
A plurality of measures can be, and usually are, taken in order to at least become as close as materially possible to said optimums, and which go from polishing all surfaces in contact with the current of admission and exhaust gases, up to the study of the most efficient cam profile for attaining a proper lift timing, and maximum opening of the valves, in other words, the diagram"of the engine under study.
When considering the ample speed range in which an engine must operate, mainly when it is placed in a vehicle, it becomes clear that a diagram suitable for certain engine speed does not comply with the same requirements at another range and, therefore, a compromise is always reached by producing an average diagram, and on this basis the materials used in the construction of the engine and its elements are selected. This solution limits the maximum engine speed, above which the valves tend to float", that is, they do not return to their seatings and, even when this does not occur, a proper filling up and scavenging of the combustion chamber is not achieved, producing a sudden decrease in power due to leaks in the first instance and imperfect combustion in the second.
In engines having overhead valves and side camshaft, the drive of the latter is transmitted to the former by means of pushing rods that actuate levers mounted on'a shaft placed at the engine head. Said rods freely rest by their lower ends on intermediate pushing or thrusting members placed over the cams and of partially hollow cylindrical shape with a concave bottom seating the end of the pushing rod, which in turn has a corresponding convex surface. Said member is placed in a suitable lodging of the engine body that guides its axial movements when actuated by the corresponding cam.
It may be gathered from the above, that once the components of an engine are already calculated and dimensioned, it becomes very difficult to modify any of them in order to obtain more efficiency, without introducing deep changes, be it in the camshaft, levers or valves themselves.
The present invention consists, therefore, in a device capable of solving the foregoing problems, which may be added to any four stroke engine, and particularly to those having overhead valves, without requiring any structural change in its component parts.
The device essentially consists in a hollow pusher within which a follower seating the corresponding pushing rod is placed, said member resting on one end of a small lever pivotally placed within said pusher while the other end of said lever abuts against a cotter secured on the side wall of the pusher guide in the engine body.
It can be inferred, from the foregoing, that by means of the described assembly a positive differential action is obtained on the pushing rod, which results in a greater valve lift from their seats and the consequent greater filling and scavenging of the cylinder. According to pertinent tests carried out with the device of the invention an increase of about 30 percent in the admission volume is attained with regard to the normal engine parameter, which results in a proportional increase in power.
The invention will now be particularly described through two embodiments and with reference to the accompanying drawings in which:
FIG. 1 shows a longitudinal section of the device; FIG. 2 is a cross-sectional view along the plane A-A of FIG.
FIG. 3 is another cross-sectional view along plane B-B of Fig. l; and
FIG. 4 shows a longitudinal section of a preferred embodiment.
ln all these figures the same reference numeral indicate the same or equivalent parts, and in the following description simultaneous reference will be made to all'four figures.
The device essentially comprises a hollow pusher 1 of cylindrical shape and closed at the end resting against cam 2 mounted on shaft 3. The body of said pusher has a longitudinal groove 4 extending along the hollow portion and engaging an elongated cotter 5 that has a step 6 which lodges in a recess at the internal wall of guide 7 of the pusher, this guide usually forming part of the engine body. Groove 4 communicateswith the hollow portion of pusher '1 at its lower end only, the elongated hole thus formed occupying approximately one quarter of the length of said groove.
Through this opening passes one end of a cranked lever 8 placed within the pusher and pivotally mounted on a transversal pin 9, while the other end of lever 8 abuts against the base of a follower l0 slidably placed within the hollow portion of pusher l and seating the end of a corresponding pushing rod 11 of conventional type, which other end actuates the levers connected to the overhead valves.
The base of the follower should preferably be convex or at least show a domed portion 12. as seen in the figures, or of any other shape suitable for allowing a proper action ofthe lever8. I Q I The foregoing completes the structural description of the present device, while its working features are as follows: when camshaft 3 rotates, the corresponding cam 2 actuates against the base of pusher 1 that starts moving upwards, while simultaneously one end of lever 8 engages the lower end of cotter 5 and rotates on pin 9 causing its other end to push follower l0 upwards along the hollow portion of pusher l, with which rod 11 receives an additional impulse that, finally, results in a greater lift for the corresponding valve.
Once the upward phase oflever2 is completed. the spring of the engine valve pushes downwards rod 11 which, in turn, actuates against follower l0 and, through pin 9, keeps the base of pusher l in contact with cam 2. It becomes evident from the above that the device of the invention provides marked advantages when applied to four stroke engines. The differential movement of obtained with it implies that when the piston is on the downward movement of the admission cycle, the admission valve increases its aperture and, consequently, a greater volume of fuel mixture enters the cylinder resulting in a greater compression index at the next cycle.
A similar feature occurs during the exhaust cycle, as the corresponding valve becomes lifted from its seat a greater distance during most of this cycle, thus obtaining an almost total scavenging. Y
The main improved functional characteristic of the invention, and one that distinguishes it from all similar known ones, lies precisely in that its actuation is totally independent from the working conditions of the engine, and the increase of volume during the admission cycle, as well as the scavenging of the cylinder, is substantially the same at any engine speed.
It is evident that the time during which the valves remain open will be, as always, the determining factor of these working phases, but the favourable increase during admission, as well as the scavenging speed, will be proportionally maintained at any engine speed.
1. Valve command device for internal combustion engines, particularly of the four stroke type, which comprises a hollow pusher that lodges a follower seating the corresponding pushing rod, the base of said follower resting against one end of a lever mounted on a pin transversally placed within said pusher while the other end of said lever engages, through an opening at the wall of the said pusher, an abutment placed in the wall of the conventional pusher guide.
2. Valve command device according to claim 1, in which the pusher has at least one external longitudinal groove having its lower portion open towards the hollow part of the pusher, said groove engaging an elongated cotter mounted at the wall ingv 3. Valve command device according to claim 1, in which the base of the follower is of convex shape or at least has a slightly domed portion in the path of the lever end the latter being rounded at least in one of its ends.