Ignition Timing Device And Method

Abstract

An ignition timing device and method for internal combustion engines having a number of cylinders and an adjustable breaker point set for firing the spark plug of each cylinder. The ignition timing system includes electronic signal pick-ups associated with each conductor running from one set of points to its respective spark plug, a light source for illuminating a timing mark when a spark plug is fired and a three position switch connecting the pick-ups with the light source such that the light source is flashed upon the firing of either or both of the spark plugs.

Description

The invention relates to timing devices and methods for internal combustion engines of the type having a rotatable cam and at least two individually adjusted sets of breaker points operated by the cam. Each set of breaker points fires a spark plug through an ignition coil, capacitance discharge ignition system or other like system. Ignition systems of the type referred to herein are conventionally used in motorcycle engines. Timing marks are provided on the flywheel or another rotating part of the engine and a timing pointer is provided. The ignition system is properly timed when each plug fires with the timing mark for the plug in exactly the same position relative to the timing pointer.

The timing of the ignition system is conventionally done through the use of a stroboscopic timing light as taught by U.S. Pat. Nos. 3,573,609 and 3,693,073. The light is attached to first one spark plug lead and then another spark plug lead. Each set of points is manually adjusted so that the image of the timing mark for the spark plug and points being timed is visually located in the desired location relative to the timing pointer. This type of timing assures that the spark plugs fire in approximately the proper timing, but does not assure that they are exactly synchronized. Maximum efficiency of the engine cannot be obtained unless all of the spark plugs fire at exactly the same time relative to the timing mark.

The ignition timing device and method of the invention assures exact synchronization in firing the spark plugs. According to the invention, each breaker point set is individually adjusted relative to the rotating cam so that its spark plug fires when the timing mark is in the desired position in relation to the timing pointer. After both of the sets of breaker points have been individually adjusted in this manner through the use of a stroboscopic timing light, the light is connected to both of the leads extending from the breaker points to the spark plugs so that the light flashes upon the firing of both of the spark plugs and the timing marks for both spark plugs are simultaneously illuminated. One or both of the breaker point sets may then be adjusted so that the images of the timing marks are exactly superimposed one upon the other in the proper relation to the timing pointer. Completion of this adjustment assures that the ignition system is synchronized exactly. There is no need to shut down the engine in order to transfer the conventional single pick-up from one spark plug lead to the other lead.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings illustrating the invention, of which there is one sheet.

IN THE DRAWINGS

FIG. 1 is a schematic view of an ignition system for an internal combustion engine of the type using a pair of independently adjustable breaker point sets;

FIG. 2 is a schematic view of an ignition timing system according to the invention; and

FIG. 3 is a schematic view of a further embodiment of the invention.

FIG. 1 illustrates an ignition device 10 for an internal combustion engine having two spark plugs 12 and 14. The system includes a distributor 16, a rotatable timing cam 18 having a single lobe, a pair of breaker point sets 20 and 22, a pair of ignition coils 24 and 26 and a battery or other voltage source 28. High tension leads 30 and 32 connect the secondary windings of coils 24 and 26 with spark plugs 12 and 14, respectively. The positive pole of battery 28 is connected to ground through the primary windings of coils 24 and 26 and breaker points 22 and 24. The negative pole of the battery is directly grounded. Conventional ignition capacitors may be used.

FIG. 1 also illustrates a timing pointer 34 fixed to the internal combustion engine and a timing ring 36 which rotates with cam 18. The ring includes two sets of timing marks 38 and 40. Timing marks 38 are located adjacent pointer 34 when spark plug 14 is fired and timing points 40 are located adjacent the pointer 34 when spark plug 12 is fired.

The ignition timing unit of FIG. 2 includes a pair of clip-type contacts 42 and 44 which are connected by high tension leads 46 and 48 to one pole of single pole switches 50 and 52. The other poles of switches 50 and 52 are connected to trigger wires 54 and 56 which are wrapped in the same sense around the legs of U-shaped stroboscopic flash tube 58. The ends of trigger leads 54 and 56 are confined in a U-shaped insulating tube to prevent short circuits. A grounded arc supressing capacitor 60 is connected to the pole of each switch 50, 52 away from the pick-ups 42 and 40 and prevents undesired radio frequency arcing between the poles of the switches when opened. A high voltage source 62 is provided to energize the stroboscopic flash tube 58 so that a flash is produced when one or both of the spark plugs is fired and the appropriate switches are closed.

In order to time the ignition system of FIG. 1, it is necessary to adjust the breaker point sets 20 and 22 relative to the cam so that the spark plugs 12 and 14 fire at exactly the correct time. The ignition system of FIG. 1 may be timed easily and accurately through the use of the ignition timing system of FIG. 2 as follows.

Contacts 42 and 44 are attached to the conductors leading from the coils 24 and 26 to spark plugs 14 and 12, respectively. The high voltage source 62 is turned on and the engine is started so that the timing marks 38 and 40 rotate past pointer 34. One of the switches 50, 52 is then closed so that the flash tube 58 will flash each time that one of the spark plugs 12, 14 is fired. The other switch is open. The flash from the tube 58 is directed at pointer 34 to illuminate it and the timing mark. The point set for the spark plug being timed is then adjusted relative to the rotating cam 18 so that the timing mark 38 as illuminated by the flash is in proper relation to the pointer 34 at the time of firing.

After one set of points has been adjusted so that the firing for its respective spark plug occurs as desired, the closed switch is opened, the open switch is closed, and the other set of points is timed in exactly the same manner as described. During this timing operation the flash from the stroboscopic tube 58 will illuminate the other timing mark relative to the timing pointer 34. The individual adjustments of the sets of points 20, 22 may be conducted without shutting down the engine. The switches 50 and 52 are easily opened and closed to indicate the adjustments required.

After both sets of points have been adjusted so that the spark plugs 12 and 14 fire at the proper intervals, final ignition tuning is done by closing both switches 50 and 52 so that the stroboscopic flash tube 58 fires with each firing of spark plugs 12 and 14. Both sets of timing points 38 and 40 are illuminated. The points 20 and 22 are finally adjusted relative to the cam so that the images of both of the timing marks 38 and 40 are exactly superimposed one upon the other and spark plugs 12 and 14 are fired in exact synchronization. This fine tuning assures the maximum performance of the multi-cylinder engine because each spark plug fires at exactly the same interval in the cycle of combustion of its cylinder. Roughness is reduced and high speed performance is enhanced.

FIG. 3 illustrates an embodiment of the invention similar to the embodiment of FIG. 2 except that inductive pick-ups are used. The inductive pick-ups 70 and 72 are placed around the high tension leads 30 and 32 and do not require disassembly of the leads or physical contact with the conductors in the leads. The inductive pick-ups are more easily attached to the leads than the clip-type pick-ups 42 and 44 of the embodiment of FIG. 2.

In addition to the inductive pick-ups 70 and 72, the ignition timing system of FIG. 3 includes a pulse source 74, a stroboscopic flash tube 76, a high voltage source 78, and a three way switching system 80 used to connect one or both of the inductive pick-ups to the pulse source 74.

One lead of each pick-up, 70, 72, is connected to an input lead of pulse source 74. The other lead of pick-up 72 is connected to contact 82 of switch 80. The other lead of pick-up 70 is connected to contacts 84 and 86. The other input lead of pulse source 74 is connected to switch contacts 88, 90, 92 and 94.

The ignition timing system of FIG. 3 is used to time the ignition system of FIG. 1 in essentially the same manner as the system of FIG. 2. The inductive pick-ups 70 and 72 are placed around the leads 30 and 32 and the pulse source and high voltage source are activated. The engine may then be turned on. With switch bridging contacts 96 positioned as shown, contacts 86 and 92 are in electrical connection and the pulse source is triggered by the output from pick-up 70 to flash bulb 76 so that the appropriate set of points may be adjusted. After this adjustment has been completed, the switch is positioned so that the bridging contacts 96 connect contacts 82 and 90 and 84 and 86. In this position the bulb 76 is flashed in response to the signals from pick-up 72 and the other pair of points is adjusted. After this has been completed the bridging contacts 96 are positioned to connect contacts 82 and 88 and 84 and 94 so that the bulb 76 flashes in response to the signals from both pick-ups 70 and 72. The images of the timing marks for both spark plugs may then be exactly superimposed one above the other to complete the timing operation.

By wrapping the trigger leads 54 and 56 in the same direction or sense around both legs of tube 50, the sensitivity of the tube is increased and reliable flashes are obtained at the high rotary speeds of 6,000 R.P.M. or more used by motorcycles.

While I have illustrated and described preferred embodiments of my invention, it is understood that these are capable of modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

Claims

1. A device for timing and synchronizing the ignition of an internal combustion engine during operation of the engine where the engine includes a distributor having a pair of independently adjustable breaker points opened and closed by a rotatable cam so that each breaker point fires a spark plug at a given time, a fixed timing pointer and a rotatable timing mark connected with the cam for rotation therewith past the timing pointer, the invention comprising a pair of electronic signal pick-up means each associated with one conductor running from one of the sets of points in the distributor to its respective spark plug for sensing the firing of the spark plug during operation of the internal combustion engine, light source means for producing a flash of light in response to the spark plug firing signal as sensed by either or both of said pick-up means, and three position switching means joining said pick-up means and said light source means for connecting either or both of said pick-up means to said light source means so that during operation of the engine the light source means illuminates the timing pointer and timing marks upon firing of either or both of the spark plugs, depending upon the

2. A device as in claim 1 wherein said switching means includes a pair of single pole single throw switches each connected to one of said pick-up means and said light source means includes a stroboscopic flash tube and a pair of trigger wires wrapped around the outside of said tube, each

3. A device as in claim 2 including an arc supressor capacitor connecting

4. A device as in claim 2 wherein said flash tube is generally U-shaped and both said trigger wires are wrapped around each of the legs of the flash

5. A device as in claim 1 wherein each of said pair of pick-up means includes inductive pick-up for sensing a pulse in the conductive path

6. The method of timing the ignition of a running internal combustion engine having a distributor ignition with a pair of independently adjustable breaker point sets opened and closed by a rotatable cam, each breaker point set firing a separate spark plug, the engine having a timing mark rotatable with the cam for a spark plug fired by each breaker point set and a fixed timing pointer, comprising the steps of:

A. flashing a timing light in response to the firing of a first spark plug to illuminate a timing mark for such plug and adjusting the first set of points relative to the rotating cam so that the firing of the first spark plug occurs when the timing mark for such plug is at a known location relative to the timing pointer,

B. flashing a timing light in response to the firing of a second spark plug to illuminate a timing mark for such plug and adjusting the second set of points relative to the rotating cam so that the firing of the second spark plug occurs when the timing mark for such plug is at approximately the same known location relative to the timing pointer, and then

C. flashing a timing light in response to the firing of both the first and second spark plugs to illuminate the timing mark and adjusting one or both sets of breaker points relative to the rotating cam to superimpose the timing mark flash images.