|Publication number||US3349760 A|
|Publication date||Oct 31, 1967|
|Filing date||Oct 20, 1965|
|Priority date||Oct 20, 1965|
|Publication number||US 3349760 A, US 3349760A, US-A-3349760, US3349760 A, US3349760A|
|Inventors||Horan John J|
|Original Assignee||Horan John J|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (10), Referenced by (17), Classifications (12)|
|External Links: USPTO, USPTO Assignment, Espacenet|
J. J. HORAN 3,349,760
ENGINE-IGNITION SYSTEMS AND COMPONENTS Fig.1
Oct. 31; 1967 Filed Oct. 20. 1965 4 Sheets-Sheet l INV-ENTOR' JOHN J. HORAN Oct. 31, 1967 J- J. HORAN 3,349,760
ENGINE-IGNITION SYSTEMS AND COMPONENTS Filed Oct 20. 1965 4 Sheets-Sheet 2 Fig. 5
INVENTOR Y JOHN J. HORAN Filed Oct. 20, 1965 Oct. 31, 1967 HORAN f 3,349,760
ENGINE-IGNITION SYSTEMS AND COMPONENTS 4 Sheets-Sheet 5 Fig.8
INVENTOR JOHN J. HORAN Oct. 31, 1967 J. J. HORAN 3,349,760
I ENGINE-IGNITION SYSTEMS AND COMPONENTS Filed Oct. 20 1965 0 4 Sheets-Sheet 4 dzww INVENT'OR JOHN J. HORAN United States Patent 3,349,760 ENGINE-IGNITION SYSTEMS AND COMPONENTS John J. Hot-an, 420 Quigley Ave., Willow Grove, Pa. 19090 Filed Oct. 20, 1965, Ser. No. 498,359 9 Claims. (Cl. 123-162) This invention relates principally to ignition systems for internal-combustion engines and to generating devices and other components principally applicable to such systems, a large number of individual, related, and interrelated concepts being disclosed. The components dis- .closed are applicable also to the improvement and simplification of older types of systems.
These systems and components introduced herein are adaptable to bbth two stroke cycle and four-stroke cycle families of both single-cylinder and multi-cylinder engines. Some kinds of systems, once considered applicable only to single-cylinder engines, now become applicable to multi-cylinder engines also.
It is an object of this invention to provide novel means for conducting and switching spark voltage.
It is an object of this invention to introduce novel types of spark plugs which coact in novel fashion with other components of internal-combustion engines.
It is an object to provide novel means for controlling spark timing.
It is an object to re-direct high voltage paths in ignition systems in a novel manner.
It is an object to provide a reliable second or auxiliary spark discharge to increase greatly the anti-stalling reliability of internal-combustion engines, particularly of single-cylinder types and of those operating under adverse loading conditions.
It is an object to expand the applicability of piezo-electric ignition to internal-combustion engines, particularly into the areas of multiplecylinder engines and of sparktiming control generally.
It is an object to provide components that will improve the reliability of so-called maverick spark auxiliary systems for very-high r.p.rn. operation of single-cylinder engines.
It is an object to introduce spark-plug-type devices having dual waterproof electrical connections.
It is an object to provide spark-plug-type means utilizing more of its own structure as a return path than has been practiced heretofore.
It is an object of this invention to provide ungrounded spark systems.
It is an object to introduce the concepts of piston- .grounding and piston switching of spark ignition.
It is an object to demonstrate that the concepts of piston-grounding and piston-switching need not be accompanied by the evils that would follow if these concepts were improperly applied, that is, without pitting of bearings, without causing glow-plug ignition when such ignition is not desired, and without loss of electrical power or loss of reliability due to the dependence on random highresistance paths to ground.
It is an object to provide piezo-electric ignition systems to be substituted for orthodox spark plugs in cylinder head structure, which systems incorporate piston-switching concepts.
attain Patented Oct. 31, 1967 181), or when subject to rain or water spray.
There are so many kinds of internal-combustion engines that there can be no such thing as a typical engine or illustration of one. They may vary from midget singlecylinder types used in model aircraft, through chain saw,
lawn-mower, small marine, and farm-standby types up to rnulti-cylinder marine, industrial, automotive and aircraft types; and there are both water-cooled and air-cooled versions of most of the types.
In order not to clutter the many drawings with detail irrelevant to the subject matter, applicant has tried to reduce the drawings to the bare essentials necessary for representation of that which is new. The portions of engines appearing as background for the invention will most nearly though not altogether correspond to those appropriate for use in such submerged applications as those disclosed in the aforementioned patents, because such underboard marine engines can generally be made simpler in the cylindenhead area than other types which must include special cooling provisions.
The extreme range of possible operating conditions, particularly as regards combustion-chamber temperature ranges in large and small chamber sizes, under varying cooling conditions, at different compression ratios, with different kinds of fuels including so'called exotic types, in two-cycle and four-cycle arrangements, etc., will render one kind of piston-switching means, for example, desirable in one engine and intolerable in another. Thus, the many alternative means disclosed herein cannot be regarded as equivalents. Cost versus life, reliability, and/ or performance will also mitigate against one approach and in favor of another. Accordingly, there is much to be taught herein "regarding alternative approaches to concept, execution, and design. It is, therefore, an additional .object of this invention to disclose samples of the variety of new approaches to be considered when designing engines to fit budgetary and performance optimums.
Other objects and novel features of this invention will be disclosed in the balance of the specification, in the claims, and in the drawings, in which:
FIG. 1 is a fragmentary cutaway view of the upper portion of a closed engine cylinder with portions of a spark plug and a partly cutaway piston showing a form of this invention.
closed engine cylinder with portions of spark plug, hightension cable, and piston, showing another form of this invention;
FIG. 5 is a cutaway view of the upper portion of a closed engine cylinder with a portion of a piston and a partly cutaway spark plug and spark-advance means in accordance with this invention;
FIG. 6 is a partly cutaway view of the apparatus seen in FIG. 5 when viewed from the right;
FIG. 7 is a cutaway view of the upper portion of a closed engine cylinder having a partly cutaway piston and a cutaway cylinder head having an integral pieZo-electric firing system incorporating spark advance;
FIG. 8 is a cutaway view of an integral spark plug and cylinder head made of ceramic material, together with a portion of a piston, in accordance with this invention;
FIG. 9 is a partly cutaway view showing a cylinder head with integral spark plug made of ceramic material, together with a portion of a piston, in accordance with this invention;
FIG. 10 is a diagrammatic representation of the energy cycles of earlier efforts to achieve piezo-electric ignition systems;
FIG. 11 is a diagrammatic representation of a mode of operation of piezo-electric firing systems being introduced in this invention for single-cylinder engines and for singlecylinder firing systems in multi-cylinder engines;
FIG. 12 is a diagrammatic representation of a mode of operation of piezo-electric firing systems for operation of multi-cylinder engines, FIG. 12 (and FIG. 11 to a lesser extent) being applicable to forms of solid-state ignition systems other than piezo-electric, when advantage is taken of the teachings of this invention in the realms of spark plugs and pistons.
Referring now specifically to FIG. 1, there is shown the upper portion of an engine cylinder 41 having a rim reenforcernent 42 for bolting purposes, to which a cylinder head 43 is secured by a plurality of screws such as 44, with a conductive metallic gasket 45 under the head 43. The spark plug 46, sealed by metallic gasket 52, has only a single electrode 47, which projects from its insulating core 48 downwardly well into the combustion-chamber. The piston 49 is partly cut away to reveal a small insert 55 which is staked in place against loosening and constitutes an annular electrode. It does not touch electrode 47, but its walls pass electrode 47 close by as the piston 49 approaches top dead center. The lateral clearance between the electrodes 47, 55 approximates the distance between electrodes of conventional spark plugs, usually somewhat less than a millimeter. Thus, as the upper edge of electrode 55 is coming abreast of the tip of electrode 47, any high-voltage charge that has accumulated across the output of an electronic, solid-state (including piezo-electric), capacitor, or other storage type of high-voltage power supply will be discharged.
A high-voltage electrical pulse, containing therein substantial high-frequency components, as in any ignition spark discharge, displays certain characteristics that distinguish its behavior from ordinary, relatively transientfree current flow. It is well known that high potentials are capable of jumping gaps, such as that of a spark plug, even under the adverse pressure condition normally existing in an engine cylinder. The discharges choose the shortest paths and tend to travel upon the surfaces of conductors.
The pulse will readily travel on the piston surface toward the inside wall of cylinder 41 and thence via any grounded component, whether the cylinder wall itself, the cylinder head 43, which can be reached via conductive gasket 45 or bolts 44, or the hex portion of the spark plug 46 via conductive metallic gasket 52. While not always absolutely essential, it is desirable to have a good ground connection 57 physically close to the area where discharge is desired.
The spark will less readily follow alternate paths via piston rings to the wall or travel via the chain of lubricated bearings, including wrist pin, connecting rod, crank pin and main bearings to a grounded crankcase or other remote ground. The more oil films and other insulative media that the high-voltage pulse encounters, the greater is the likelihood of excessive voltage drop across one or more of these obstacles and, consequently, the less the capability the spark energy has of jumping the total gap to ground. If the energy travels the indirect paths, as some of it will unless a far better path to ground always exists, damage will be done to bearing surfaces by transiting pulse, causing rapid deterioration of fine running finishes. If the good ground connection 57 is allowed to deteriorate, the engine may still run because of the availability of alternate grounding paths for spark energy, but at serious risk to the component parts. Conceivably, applications may exist for cheap devices with short life-times where such deterioration can be tolerated.
Referring now to FIG. 2, there is seen another engine cylinder 41, 42, from which head 84 is separated by insulating gasket 61. Besides the direct grounding of the high-tension-return cable 83 to the cylinder 84, via nuts 81, 82, another distinguishing feature is the shunting of the high-voltage pulse from the central electrode 85 to the shell 86 of spark plug 87 via step boss 88 on piston 89. The location of spark plug 87, and particularly of step boss 88, so close to the wall of the combustion chamber, where there is an intimate thermal relationship between externally cooled cylinder 41, 42 and step boss 88, exercises a powerful cooling influence on these projections as a precaution against auto-ignition caused by local overheating.
Referring now to FIG. 3, the relationships of cylinder 41, rim 42, insulating gasket 61, insulating washer 63, cap screw 44, and cylinder head 90 are similar to the relationships observed among corresponding parts in prior FIG. 2.
The spark plug 91, however, is quite different in that it has two central electrodes 93, 92, which are shunted at the proper instant by insert plug 94 on piston 95. Although it is not fully apparent in FIG. 3, spark plug 91 is set far back, close to the wall of cylinder 41, though far enough removed therefrom to assure against premature shunting of the electrodes 92, 93 by the wall 41.
The ceramic core 96 of spark plug 91 is threaded at its upper end to receive knurled and threaded cap 97, which contains an O-ring seal 98. The upper ends 99, 100 of electrodes 92, 93 project from the upper surface of the core 96; and the split-apart ends 101, 102 of dual cable 103 contains metallic wedge sleeves 105, 106 which, respectively, receive these electrode ends 99, 100. Elastic biscuit 107, preferably of silicone rubber, conforms between the inner surface of cap 97 and the aforementioned components which it is required to seal within the cap 97. It is liberally coated just before assembly either with an insulating grease or with a room temperature vulcanizing (RTV) silicone compound, which coating extrudes out together with the upper portion 108 of biscuit 107 and is wiped away from external surfaces after cap 97 has been securely tightened and has fully compressed biscuit 107 as shown. Dual cable 103 is a figure-S-shaped extrusion of high-tension insulation carrying twin conductors 109, 110 from the point of generation of electrical potential, which preferably leaves both sides locally ungrounded. Gasket 79 is preferably but not necessarily of an non-conductive type.
The structure shown in FIG. 3 is applicable, not only to solid-state, capacitative, piezo-electric, and electronic power supplies, but also to spark-interrupted, inductivelycoupled, primary-secondary coil systems receiving power from either magnetos or batteries, because of the projection from open, leaky, or short circuits afforded by the twin-figure-S cable 103, the twin insulated electrodes 92, 93 of spark plug 91 and the moisture-proof overall design. When used with most inductive systems, it is necessary that the overlap between electrodes 92, 93 on one hand and insert plug 94- on the other be suificient to assure contiguity of these electrodes prior to the instant when the primary gap opens. In fact, when magnetofired singlecylinder, two-cycle engines are turning up at very high high-rpm. rates, there is danger of stalling the engine when maverick spark advance cuts in, unless overlap of electrodes 92, 93 versus plug 94 has already begun.
Referring now to FIG. 4, the spark plug 111 has a single central electrode 112 which is shunted directly to the cylinder head 113 by piston projection 114. Hightension return cable 83 is grounded to the head 113 by cap screw 115.
Referring now to FIGS. 5 and 6, there is shown a mechanically advanced spark plug 120 connected by a waterproof cap 121 and a rubber biscuit 122 similar to caps 97 and biscuit 187, 108, respectively, of FIG. 3, to a twin high-tension cable 123 having a cross section differing somewhat from that of prior cable 103. Spark plug 120 is unthreaded, and is capable of being retarded by lifting its trunnions 124 which slide in the lever 125, pivoted at 126 to the cylinder head 127. The ceramic insulator 128 carries two high-tension electrodes 129 and, for this reason, has an elongated cross section.
In place of threads and gaskets, there is a series of flow restriction grooves 138 banded around the tightly fitting metal shell of the spark plug, which has a sharp edge 131 to further help break up leakage flow, and which may have a cross-section larger but similar in outer contour to that of cable 123. A replaceable metal plate 132 is secured to the piston boss 133 to retard pitting wear and to afiord a means of gap adjustment.
Referring now to FIG. 7, there is shown an arrangement that combines in one housing the spark advance function of FIGS. 5 and 6 with a complete head-mounted, sealed piezo-electric spark-ignition system. The lever 270 is grooved to permit it to be dropped into the slotted housing 271 before the pin 272 is installed to retain lever 270 against anvil 273, which is sealed by diaphragm 274 to gland 275 containing G-ring 2'76. Actuation of lever 270 against anvil 273 causes anvil 273 to exert force downward upon the ferroelectric element via diaphragm 274. Gland 277, sealed by O-ring 278, seals projection 288 against leakage of silicone fluid 245.
Element 150 rests on strong ceramic block 221, the annular space around element 150 being filled by an elastomeric annulus 164. Block 221 is in turn supported by annular pedestal 222, which may be of strong ceramic or stiff metal. High-voltage electrode 167 acts as a collector for feeding firing voltage via hot pin 223 to the sleeve adapter which fits electrode 238 and slides up and down as carried by ceramic core 281, which, in turn, slides vertically in housing 282, of which cylinder head 293 is a component part. Leakage from combustion chamber 283 into housing 282 is minimized by grooves 284, together with step-cut ring 285 and metallic O-ring 286, the relatively small amount of leakage escaping via vent 287. O-ring 288 is the lower seal for the chamber containing the piezo-electric element.
Rotation applied to spark-advance screw 295 causes it to advance against gland 277 containing O-ring 278, which seals in the silicone fluid 245 that fills all space within the housing 282 not required by the components therein. Inward movement of gland 277 hydrostatically forces core 281 downwardly further into combustion chamber 288. A tiny notch 296 in the upper surface of pedestal 222 permits the fluid to move from one compartment of the chamber to the other. The spark advance is thus controlled by screw 295. The electrode 288 and piston insert 289 provide a spark gap. Rivet 290, snugly fitted in bolting flange 291, initiates the pulse return path, which reaches element 150 via bolting flange 291,
conducting gasket 292 and screws 295, cylinder head/ housing casting 293, gland 275, and diaphragm 274. Thus, a single enclosure houses both sparkgenerating apparatus and spark-advance means; and these, together with the timer or distributor and the firing electrodes, are one assembly, with no external wiring. Referring now to FIG. 8, there is seen a cylinder having a bolting flange 191 and piston 192, the piston having two bosses 193 and 194. Clamp ring 195, secured by cap screws such as 196, holds the ceramic cylinder head 197 firmly to the cylinder, compressing gaskets 198 and 199, which may at choice be of conducting or insulating materials. No current can be delivered to the cylinder clamp ring since the ceramic cylinder head is not electrically conductive. It will be noted that the upper portion of ceramic cylinder head 197 is similar to related ceramic structure appearing in FIG. 3 and that, by employing similar auxiliary structure such as biscuit 107 and cap 97, a twin high-tension cable such as 183 may be sealed to cylinder head 197 with a waterproof joint.
It will also be seen htat the combined horizontal measurements of piston bosses 193 and 194 amount to about one cylinder radius, thus they are approximately equal to the interval between electrodes 208, 281 in the combustion chamber.
The purpose of such structure will become clearer as we study FIGS. 10 through 12. It is sufiicient momentarily to note that electrical currents are more easily transmitted through ionized media such as the atmosphere of the chamber after ignition of the charge therein, than through compressed gas-air mixtures. When the power stroke is well advanced and the piston has moved well downward in the cylinder, the total spacing of the two electrodes 2% and 201 from each other on one hand, and from the cylinder wall (which conceivably could serve as part of a shunt path between the electrodes) on the other hand, effects the maximum possible resistance in way of undesired current flow between the two electrodes.
It is not commonplace to find ceramics used structurally in internal-combustion engines because their thermal conductivity is even poorer generally than that of ferrous metals. The use of ceramics pre-supposes that, for the particular fuel being used, for the engine size, possibly smallbore, and for the particular environment, which might be an immersed engine that would otherwise stiffer from overcooling, with other conditions also being favorable to ceramics, the surface temperature in the combustion chamber will not produce pre-ignition or detonation. Quite obviously, water-jacketed arrangements could be imposed upon cylinder heads comparable in structure to those of FIGS. 7, 8 and 9, particularly in the form of glaze-bonded two-piece heads.
Referring now to FIG. 9, in which cylinder head 210 has only one electrode 211 projecting into the combustion chamber alongside the single piston boss 212, it is seen that a conductive gasket 213 is placed between clamping ring 214 and bolting flange 191. This conductive gasket 213 has a tubular projection 215 which is bent over the edge of bottom flange 191 and mechanically affixed to and electrically grounded to return high-tension cable lead 216 by cap screw 217.
When the piston 218 has moved away from the position shown, the total effective spacing between electrode 211 and any grounded area such as the inner rim of cylinder 198 will be about the same as the total effective spacing encountered in the prior FIG. 8. Again, therefore, we obtain, by electrode separation, the maximum resistance to current flow when spark transit is not desired, as, for example, when it is desired that the spark go to another cylinder.
Referring now to FIG. 10, the solid circle represents the 360 travel of an engine crankshaft (or camshaft in a four-cycle engine) making one clockwise revolution.
'2 The mark represents to-p-deadcenter position of the piston and of its crank at the beginning of downward travel on the power stroke. The condition portrayed is essentially the same whether we are dealing with two or four-cycle engines, with the principal exception that the piezoelectric device will generally be actuated by the camshaft rather than by the crankshaft in the latter type.
The earliest types of piezoelectric actuators for engine ignition were of the impact type. The hammer struck the polarized ferro-electric ceramic material, stressing the material sharply, but unfortunately with little uniformity in the developed stress peaks, which, because of the extremely rapid rate of rise and short overall duration, are very difiicult to measure accurately. The magnitude of the stress and its distribution pattern can generally only be inferred roughly by indirect measurement means. Like other ceramics, the piezoelectric ferroelectrics are much stronger in compression than in tension; and the consequent brittleness makes them very subject to fracture under impact-type stress applications. Even more serious, however, insofar as general engine reliability is concerned, is the unpredictability of voltage magnitudes and resultant ability or lack thereof to jump spark gaps in a running engine. If the gap breaks down too early (at a low voltage value during the stress cycle) a spark of desired vigor may not be available later when needed. If the stress on the ferro-electric element then continues to rise, the voltage value may not again rise high enough to jump the gap once more. If this happens, the relaxation phase, during which voltage of opposite sign normally builds up with almost equal rapidity, must first cancel the charge remaining before the voltage of opposite sign can be generated. Since it is usual for the second or relaxation pulse to contain less energy than the first, the second pulse is then even more likely to fail to bridge the spark gap, and, to make matters Worse, it may even leave a partial charge of wrong sign on the piezo-electric element and thereby weaken the next stress-rise pulse.
If it is desired that an impact system deliver a spark at a crank angle 04 before top dead center, as shown in FIG. 10, the ferro-electric element must be struck at that instant. Thus we see the spike having a dimension S representing the maximum stress peak occurring at any point in the piezoelectric body at that instant. Were the impact system able to produce substantial uniformity of stress throughout the element, then S could also represent the value of voltage or energy so delivered. Actually, of course, there are several reasons why this is not so, one being that such a dynamic phenomenon as the impact on the ferro-electric of a bouncing hammer produces a non-uniform stress distribution. Thus, the delivered voltage will not reach a magnitude concomitant with the stress peak S In order to deliver an impact-generated voltage comparable in magnitude to the distance between the solid circle and the larger concentric short-dashed circle, it is therefore necessary that the peak stress level S considerably exceed the level of uniform squeezegenerated stress that would produce the same voltage.
The next piezo-electric stressing devices which appeared in the art were mechanisms employing levers of great mechanical advantage, by means of which high squeezing forces were obtained. These squeezing devices are customarily used with a rotating high-voltage distributor or commutator that first delivers the stress pulse to the spark plug at the instant defined by angle 0: and then deliberately grounds or wastes the subsequent elastic re covery pulse, because of inability to apply this pulse properly and because of the likelihood that failure to waste by promptly grounding it would cause trouble on the next pressure rise cycle.
In order to be certain that the piezo-electric element will have available a voltage of adequate value at the instant of commutation which is also represented by angle a it is necessary to make sure that the full voltage stress generated is reached before the arrival of the commutating arm, that is, that it be reached at some early angle such as ,8 The distorted-bearing actuated and tuned devices of this prior art will continue to increase the stress upon the ferro-electric (still represented by the long dashed line) until, at top dead center (0) the stress has risen well beyond the level that was required for gap jumping, to a new level represented by S and then is allowed to fall back to 0, at which time the voltage generated by the elastic recovery pulse must now be discarded by short circuiting it to ground.
It must not be forgotten that the typical distortedbearingactuated and timed stressing devices, together with their auxiliary high-voltage oornmutators, lose some energy outside the combustion chamber due to the commutation process itself, and are subject to further losses due to contamination, presence of moisture, long grounding paths, etc.
In FIG. 11 we new study, for comparison with the old arts, the cyclical performance of the simple one-cyclinder piezo-electric devices of this invention which are piston timed and need no springs, hammers, distributors, commutators, grounding devices, or any other form of auxiliary timing device.
It is assumed that we again desire the same angle of spark advance 41 as before and that we desire to apply a stress level S sufficient to produce a voltage capable of jumping a spark gap or pair of gaps in the combustion chamber.
Accordingly, for a given total element cross-sectional area and length, made of the same composition and polarized by the same field, by the time the crankshaft again reaches angle .5 short of top dead center in FIG. 11, we need to have built up, by means of the actuating cam, the same stress level in the piezo-electric that was previously needed in FIG. 10 at angle 5 for assurance of delivery of an adequate voltage at angle a However, although the same ferroelectric could again tolerate the same maximum stress level S that was produced by the distorted bearing cam in FIG. 10, we do not need to develop a maximum stress level at any time that is any higher than that previously reached at 5 that is, S Then, after angle a has been reached, the actuating cam may release the stress completely by the time it reaches angle 7, which may have any value between 0: and a Whereas in the distorted-bearing, commutator-timed device of FIG. 10, the setting of the commutator determines the value of a, (assuming that the timer is not set to fire too soon), in the FIG. 11 system the instant before top dead center when the boss or other projection on the piston comes first abreast of the spark plug electrode now determines a Angle a when the piston projection begins to depart downward from its position alongside the electrode, is equal to 04 After the shaft has rotated beyond m the recovery pulse no longer can be delivered via the piston. Thus, the angle defining the instant of release of cam pressure upon the piezoelectric, may have any plus or minus value between 1x and a Normally, since angle '7 in this system represents an opportunity too good to miss for a well timed second attempt to ignite a balky engine, it would be quite practical to locate the drop-off of the cam slightly before top dead center, as indicated by 'y in FIG. 11.
If the diameter of the solid circle represents the entire piston stroke, then the distance it represents, because of the geometry of crank-driven pistons, somewhat less than the stroke overlap between the piston boss and the spark plug electrode. The effective value of h is further increased when the high levels of voltage developed in fast running engines causes the spark to jump even sooner. (Rotary timing distributors in old style piezo-electric systems are likewise subject to premature jumping due to presence of a high voltage and close-set spark plugs.)
If we desire to combine piston timing with the distortedbearing type of squeezing device, we may refer back to FIG. 10 and increase the negative value of angle [3 At the same time we could optionally reduce judiciously the maximum intensity of squeeze from S to S provided we make certain that the long-dashed eccentric circle of FIG. 10 continues to intersect the short-dashed large circle to the left of angle a As we increase the negative value of angle m, or as we reduce S we note that the positive value of ,8 will correspondingly decrease. As we continue to cause reduction of the value of B its value becomes less than that of angle When this happens, angle [3 acquires a value within the allowed range of angle 7 and we can wholly dispense with the rotary high-voltage commutator in favor of the simple flanking arrangement between spark-plug electrode and piston boss that has been disclosed herein.
Returning once more to FIG. 11, the renewed stressing of the piezoelectric element for the next cycle may begin as soon as the crank angle exceeds angle 04 We may designate as angle 8 the angle at which the camming device begins again to squeeze the ferro-electric. For single-cylinder engines, we may, therefore, give the cam an outline in which the rate of height increase in a function of the solid curve that traverses the space between the two circles. The drop-otf that ends at angle 7 may have any desired steepness. It is at or toward the end of this drop-off that the second electrical pulse, the elastic-recovery pulse, is delivered to the spark gap.
Carrying on with what was developed in FIG. 11 and referring now specifically to FIG. 12, it is seen that the entire cycle of FIG. 11 may be very practicably compressed into less than 90 of crankshaft rotation of FIG. 12. Thus, we can obtain four cycles per revolution instead of one. The only change that must be enforced is that the long slope of the rise curve of FIG. 11 must now be compressed anglewise and timewise into a much sharper stress rise, which, however, is still a squeezing and not an impact action. Each of the four squeezes per revolution develops full voltage value at one of the successive ,8 positions, each such voltage being discharged at the next 11 angle as we again move clockwise around the circle.
For illustration purposes only, and not of necessity, all of the angles designated as 7 in FIG. 12 now have a positive value, whereas 7 has a negative value in FIG. 11. Applicants preference, though not a rigid one, is for slight negative values to be assigned to the angles 7 so that the earlier recovery pulse, if needed for ignition, will cause the piston to deliver greater power to the crankshaft.
The most important point taught by FIG. 12 is that, if we have as many as [four pistons spaced 90 apart in an ignition group in an engine having a larger number of cylinders, these cylinders can receive all of their ignition pulses from one piezo-electric element, without employing any mechanical rotating commutator or distributor in the high voltage circuit. The four individual pistons decide for themselves, by their relative positions in the cylinders, which one will trigger the discharge of and obtain the benefit of each successive pair of ignition pulses.
Under certain conditions, the performance of cylinders having pistons firing in such close succession, as in some V-types and parallel block-types, can introduce a new difficulty. Obviously, if ordinary spark plugs, not pistontimed types, were used, the piezoelectric pulse intended for a second cylinder would be most likely to dump itself into the spark-plug gap in the cylinder that has just been fired, because of the easy discharge path provided by the highly ionized flame remaining in that cylinder.
On the other hand, the piston-timed and shunted electrode pairs shown herein before have very substantial gaps when the piston departs; so the energy losses across such gaps will usually be light.
Recalling, however, as stated in the beginning, that the ranges of thermal and other conditions in internal-combustion engines are extremely wide, we obtain additional assurance from the expedients shown in FIGS. 8 and 9 that the gap switched by the piston can be very large if necessary, the gap size being limited only by the radius of the cylinder.
It is obvious that various combinations can be made of the above inventive features without departing from the true scope of this invention, such combinations being apparent immediately to those skilled in the art. Obviously also, major improvements over the old art can be realized by the adoption of only portions of the inventive features shown or of readily inferrable equivalents. It is, therefore, intended to include in the claims such portions and equivalents as may fall within the true scope of my invention. My invention is not to be limited to the specific forms or arrangements to which I have limited my descriptions, drawings, and claims for the sake of brevity and expeditious prosecution.
Therefore, I claim:
1. A distributorless ignition system for an internalcombustion engine, said system comprising:
at least one combustion chamber,
a piston reciprocating in said chamber,
an apparatus containing a polarized ferroelectric body having two opposite poles,
said apparatus including means for cyclically squeezing said body sufficiently to generate a high-tension, ignition-spark voltage between said poles, and
an insulated conductor carrying said voltage from one of said poles and leading sealably into said chamber via the upper portion of the wall thereof,
said apparatus being mechanically phased with said piston to provide said voltage when said piston is compressing a combustible mixture,
said piston having an electrically conductive upper portion so configured and aligned. as to pass close to said conductor leaving a small gap at a timely instant before said piston has completed compression of said mixture,
said conductive portion being at said instant in circuit also with the other pole of said ferroelectric body,
whereby said voltage is discharged via said conductive portion.
2. A system as in claim 1,
said system having also a second conductor leading from the other of said poles into said chamber via the upper portion of said wall,
said conductive portion being so configured and aligned as to approach closely and electrically shunt both of said conductors at said instant. 3. A system as in claim 2, said slecond conductor also being insulated from said wal 4. A system as in claim 3,
part of said upper portion of said wall being composed of electrically insulating material through which both of said conductors enter said chamber.
5. A system as in claim 1,
said conductive portion being continuously in circuit with said other pole.
6. A system as in claim 1,
said conductive portion making electrical contact in series with said other pole before said first-mentioned pole.
'7. A system as in claim 1,
said apparatus being phased to release pressure upon said ferroelectric body while said conductive portion still remains close to said conductor,
whereby a second spark voltage of opposite polarity is generated and discharged via said conductive portion.
8. A system as in claim 1,
said upper portion of said wall having an opening therethrough leading to an auxiliary sealed chamber containing a fluid material,
11 said auxiliary chamber having an adjustment for displacing said fluid material, at least one of said conductors being movably coupled to said fluid, whereby said instant may be selectively varied. 9. Ignition means as in claim 1, said Wall having an extension supported thereon, said extension constituting enclosure means for said apparatus.
References Cited UNITED STATES PATENTS 582,540 5/1897 Mueller 123-169 12 Stewart 123162 X Violet 123-169 'Rohde 123169 Anderson 123-162 Peters et al. 123169 Harkness 123-169 Feldman 123148 Farrell 123--148 FOREIGN PATENTS Great Britain.
LAURENCE M. GOODRIDGE, Primary Examiner.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US582540 *||May 11, 1897||Igniter for explosive-engines|
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|U.S. Classification||123/162, 123/163, 123/169.0EL, 123/642|
|International Classification||F02P15/04, F02P3/12, F02P15/00, F02P3/00|
|Cooperative Classification||F02P15/04, F02P3/12|
|European Classification||F02P15/04, F02P3/12|