US1208926A - Ignition device. - Google Patents

Description

B. DICK & V. A. FYNN.

IGNITION DEVICE. APPLICATION FILED 10H 19. I915.

Patented Dec. 19, 1916.

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5 Ill/gEA/IOR A TTUR/VEY IGNITION DEVICE.

Specification of Letters Patent.

Patented Dec. 19, 1916.,

Application filed July 19, 1915. Serial No. 40,602.

To all whom it may concern Be it known that we, BURNS DICK and VALilRE A. FYNN, subjects of the King of England, residing at the city of St. Louis, Missouri, United States of America, have invented a certain new and useful Ignition Device, of which the following is such a full, clear, and exact description as will enable any one-skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, forming part of this specification.

Our inventionrelates to internal combustion engines, and more particularly to improved means for causing the maximum explosion pressure to occur at the most'eflicient. points of the crank revolution forall torque conditions.

It is well known that an engine running at'a given number of revolutions and developing little power, ought to operate with acertain setting of the spark in order to utilize the fuel to the best possible advantage, and that this spark setting must be altered in order to obtain the best results if the load is changed while the speed is kept constant. Thus, if a combustion engine working at a given speed and maximum load requires a 15 degree leador advance of the spark, then it will require a greater spark advance when the load is thrown off but the speed is kept constant. a The greater the torque developed by the engine at a given speed, that is, the greater the load on the engine, the greater also will be the degree to which the charge will be" mechanically compressed in any cylinder at the end of the compression stroke, because an increase ,in torque requires an increase in air and fuel. The time which elapses between the occurrence of the ignition spark within the combustion chamber and the development of the maximum explosion pres sure, also varies to a marked extent and de-' pends on therate of flame propagation, and

this rate itselfdepends on a number of factors, one of which is the location of the spark gap with reference'to the'main body l of the compression chamber.

The nearer the spark to the main bodypf the compression chamber, the. more rapid the flame propagation and the shorter the time interval between the occurrence of the ignition "A milled' head spark and of sure. a

In carrying out our invention we make use of the fact that the degree of mechanical compression changes with the engine torque orload, and also of the fact that the location of the spark gap'with'reference toFthe main body of the compression chamber has an in- 'fluence on the time interval between the oc currence of the ignition spark and of the maxnnum explosion pressure, in order to cause th1s maximum explosion pressure to occur at that polnt of the revolution at which it will be most efiicient under the prevailing load conditions.

Our invention whlch shows one embodiment thereof;

The figure illustrates a' spark plug adapt,- ed-to be screwed into the wa1l2 of the cyl- \inder of a combustion engine, in the ordinary way. This improved spark plug comprises a body 3 within the cylindrical chamber 7 of which slides a springfcontrolled piston 11'. This chamber the maximum explosion pres I i will be better understood by reference to the accompanying drawing,

the cylinder of the engine by means of a v suitable annular projection of the piston coming into contact with this cap in time to prevent the spring 9 from being crushed. Therod 5 is attached to the piston 11 but insulated therefrom by means of suitably shaped bodies of insulating material, 6 and 10. The rod 5 is so held as to be compelled to follow each movement of the piston 11.

ablewasher, makes it possible to readily connect this rod to the distributer 17 or high tension side of the ignition system. At its oWer end, the rod 5 carries a sharp edged disk 12 of I somewhat smaller nut, co6perating with a suit diameter than the circular opening 15 in the lower end of the spark plug. This disk, which forms the insulated terminal of the spark plug, may have a serrated edge, if desired. the

'ence of the disk 12 and some part of the inner wall of the circular opening 15. \Vith the piston in the position shown in the figure, the ignition spark would occur deep 'bustion chamber 16.

occur between some part of or ignition chamber, formed 15 at a point removed a confrom the body of the com- NVith the spring 9 fully extended, the spark would be produced at the lower edge of the pocket 15-and in closest proximity to the combustion chamber 16. In the figure the spark plug is shown connected to a battery ignitionsystem, the primary circuit of which comprises the interrupter '22 actuated by the cam 23, the storage battery 21 and the primary 19 of the spark coil. The secondary ignition circuit comprises the secondary spark coil winding 18, thehigh tension distributer '17 and the spark .gap in the pocket 15.

The mode of operation of our improved ignition system is somewhat as follows: Normally, and with no-pressure in the combustion chamber 16,the spring9will be in control of the piston 11 and hold same in that position in which it rests on the shoulder 14, in which case the terminal disk 12 will occupy the position indicated by the dotted-lines at 13. When the engine is started,

in the pocket, by the opening siderable distance a certain pressure will be developed in the combustion'chamber 16, at the end of each compression stroke, and this pressure, actin on the piston 11,, will force same upwar away from the shoulder 14against the effort .of the spring 9 and thus push the terminal disk 12, and thereforetheignition spar farther and farther away from the main body of the combustion chamber and higher into the pocket 15 as the fuel pressure increases. he mechanically produced pressures at the end ofthe compression stroke vary over a wide range; beginning with a few pounds whenever the torque exerted by the engine is small, and reaching values ofabout 60 or more pounds when the engine is developing its maximum torque; The spring 9-is so adjusted that, when the maximumcompression occurs, the piston 11 is forced into the position shown i the figure; Since the 'ignition spark must always the terminal disk 12 and some partof the inner wall of the pocket 15, then, with low compression values, that is, when the engine is developing s a small torque, the spark will occur close to Y the mam body of the compression or explospark in our improved the occurrence of location of the the main body of the combustion chamber 16 and from the lower opening of the pocket 15, so will'the rate of flame propagation decrease, thus causing the time interval between the occurrence of the ignition spark and of the maximum explosion pressure to increase. We, thus achieve, by the means described, an effect equivalent to that usually secured by causing the spark to always occur at the same point but changing the timing thereof. This indirect method of timing the spark, of course, also takes care of the change in compression pressure due to a change in the engine speed. With most carbureters, the compression pressure decreases with increasing speed, for a constant opening of the fuel valve, which is controlled from the drivers seat. This decrease of compression pressure with increasing speed, is due to the fact that as the speed increases the amount inder diminishes, although the opening of the fuel valve is kept constant. As the compression pressure decreases with increasing speed, so. does the time interval'diminish which elapses between the production of the ignition system and the maximum explosion pressure, thusproducing the effect of a spark fuel valve opening. a

Because the explosion pressure developed 7 in the cylinder reaches values greatly in excess of the pressures mechanically produced at the end of each compression stroke, we

of mixture sucked into the cyladvance with increasing speed for a constant have made provision for positively limiting the upward stroke of the piston 11. Without this precaution, the spring 9'would have to be made strong enough to withstand the maximum explosion pressure, which may reach 200 pounds per square inch, and could not be made sufliciently sensitive to the changes in the pressure occurring at the end of the compression stroke, on which the operation of this device depends, and which usually vary from about'5 to about'60 pounds per square inch.

, The pocket, or lgnition chamber, 15 af+ fording communication between the chambers 7 and 16, is preferably made conical in shape, n order to compensate crease 111 resistance of a given sparkv gap for the inwith rising I compression values. Experiments have shown that the voltage necessary in order to force a spark across a spark gap of a given length increases rapidly, although not quite proportionately with increasing compression pressure. It is therefore clear that if the ignition voltage and the spark gap length remain constant, then the intensity of the spark must decrease with 'increasing compression pressure.' In fact, the spark may, under those conditions, fail altogether. In order to take care of these conditions, the distance between the terminal disk 12 and the wall of the pocket, diminishes as the piston 11 rises.

Having fully described our invention, what We claim as new and desire to secure by Letters Patent of the United States is:

- 1. In an internal combustion engine, an explosion chamber, fuel 7 means governed by the pressure of the fuel in the explosion chamber for varying the position of the point of initial ignition of the fuel to vary the time between the said ignition and the development of maximum explosive pressure.

2. In an internal combustion engine, the combination of an explosion chamber, a movable spark electrode, 'and.means'operated by the pressure to which the fuel is subjected in the explosion chamber for moving said spark electrode to change the point at which the ignition spark is produced.

3. In an internal combustion engine, an explosion chamber, anignition chamber in communication with the explosion chamber,

ignition'means in the ignition chamber, and means governed by the pressure of the fuel in said chambers for varying the distance of the point ofignition thereof from the main body of fuel in the explosion chamber.

4. In an internal combustion engine, the

combinatlon of an explosion' chamber, a fuel ignition chamber communicating therewith, a spark electrode in said ignition chamber, and means operated by the pressure of the fuel in said chambers for varying the position at which the ignition spark is produced.

5. In an internal combustion engine, the combination of an explosion chamber, a sparking plug having a chambered body and a. piston movable therein, the movement of ;aid piston being governed by the pressure of nd electrode having a pocket 15 is so arranged that the.

igniting means, and

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the fuelin the explosion chamber, a movable the piston, and a secelectrode controlled by plurality of sparking points adjacent to the path of movement of the movable electrode whereby the position atwhich the ignition sparks occur will vary with the different fuel pressures in the explosion chamber.

In an internal combustion engine, the combination 0f an explosion chamber, a sparking plug having a chambered body and a piston movable therein, the movement of said piston being governed by the pressure of the fuel in the able electrode controlled by the piston, and a second electrode having a plurality of sparking points at different distances from the path of movement of the sparking point of the movable electrode.

7. A spark plug comprising a chambered body forming an electrode, a piston movable therein, a movable electrode operated by said piston, the movement of said piston and electrode being controlled by the pressure of the fuel charges to be ignited to produceignition sparks at different points within the 01121111 bered body for different pressures.

' 8. A spark plug comprising a chambered body forming an electrode, a pistonmovable therein, a movable electrode operated by said piston, resilientmeans for opposing the movement of piston in one direction, means limiting the movement of piston in said direction, the movement of said piston and electrode being controlled by the pressure of the fuel charges to be ignited to produce ignition sparks at different points Within the chambered body for different pressures.

9. In an internal -explosion chamber and piston therein, fuel igniting means and'means controlling the igniting means to cause the time of occurrence of maximum explosion pressure with reference to piston position to vary with variations in maximum fuel pressure in the explosion chamber.

In testimony whereof, we have hereunto set our hands and aflixed our seals in the presence of the two subscribing witnesses.

BURNS DICK. 1. a] VALERE ALFRED FINN. [a 5. Witnesses:

CARL C. ADAMS, H. HENZE.

combustion engine an explosion chamber, a mov-

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