US3139081A - Distributor advance mechanism - Google Patents

Description

June 30, 1964 H. TYZACK DISTRIBUTOR ADVANCE MECHANISM Filed June 22, 1962 INVENTOR. Harold Tyzack %-Z@d z Ma.

United Statesv Patent 3,139,081 DISTRIBUTOR ADVANCE MECHANISM Harold Tyzack, Schiller Park, Ill., assignor to Motorola, Inc., Chicago, 111., a corporation of Illinois Filed June 22, 1962, Ser. No. 204,467 7 Claims. (Cl. 123--143) This invention relates to distributor and timer mechanisms for use in the ignition systems of internal combustion engines and more particularly to an advance system for such a mechanism.

It is well known in the distributor art that as the speed of the engine increases it becomes advantageous to supply the spark to the distributor rotor more quickly. This is because despite the increased number of cylinder firings,

the fuel takes the same amount of time to burn. Therefore, maximum engine efficiency requires that the pulse be supplied to the spark plugs proportionally sooner as speed increases. g

In an ignition system of the magnetic inductive pulsing type, there may be an inherent problem of increased electrical delay. In this type of system, pulses are produced by intermittently causing the flux through inductance coils to increase and decrease. Because the system may use only that portion of the pulse generated by the magnetic flux as the flux is decreasing, a certain amount of electrical delay results. Previous advancing arrangements are unsuited for the large advance needed to offset this electrical delay because they also advance the distributor rotor which selectively distributes pulses to the spark plugs of the engine. Stniicient advance to offset the electrical delay causes the rotor to advance far enough to cause sparking to the wrong electrode, whereby engine efliciency is substantially reduced and the distributor electrode de teriorates due to burning.

Accordingly, an object of this invention is to provide an improved low cost distributor mechanism wherein the spark may be advanced substantially more than in prior units.

Another object of the invention is to provide an improved low cost distributor mechanism in which a rotary member operating a pulsing circuit may be advanced while at the same time the rotor is retarded.

A feature of the invention is the provision of a distributor having an armature and rotor coupled to a drive shaft through an advance mechanism so that the armature may be advanced with respect to the drive shaft while at the same time the rotor may be retarded with respect to the drive shaft.

Another feature of the invention is the provision of a distributor, including a sleeve mounted rotatable armature, a rotor fixed to a second sleeve, and a centrifugal advance mechanism provided with rotary plates each fixed to respective sleeves for advancing and retarding the respective sleeves to advance the armature and retard the rotor.

In the drawings:

FIG. 1 is a schematic view of the circuit associated with the invention and includes a top plan view of a portion of a mechanism incorporating the invention;

FIG. 2 is a sectional View taken along the line 22 of FIG. 1 with the distributor cap and rotor added; and

FIG. 31s a sectional View taken along the line 3-3 of FIG. 2with part broken away.

In accordance with the invention a distributor and timer unit for use in the ignition system of an internal combustion engine is provided with an improved advancing arrangement. Rotary conductor means for distributing the pulses to the various spark contacts of the ignition system are mounted on a sleeve concentric with and rotatable on the distributor shaft. A rotary wheel for operating the pulse producing system is mounted on a second sleeve concentric with the sleeve having the conductor means thereon. The pulse producing system could be any system which produces variations in voltage for igniting fuel in the cylinders of the engine. For example, this might be a cam for opening and closing breaker points, or an inductance coil arrangement. Both sleeves are coupled to a centrifugal advance unit. As a result, the advance unit may angularly advance the rotary wheel with respect to the distributor shaft, and angularly retard the conductor means with respect to the distributor shaft as the speed of rotation of the distributor shaft increases. This permits a wide variation in the amount of advance, while at the same time prevents the distributor rotor from advancing too far and sparking to the wrong spark contact.

The ignition system is illustrated in FIG. 1 for use in an internal combustion engine 10 having a plurality of cylinders which are fired by signals supplied to terminals 11. The engine is mechanically connected to a distributor having a rotary contact 12 which extends from rotor 13 to selectively apply high voltage pulses to contacts 14 connected to terminals 11. The distributor therefore operates at any time that the engine is turning over, whether when operating on its own power or when being cranked by a starter or the like.

The pulsing unit of FIG. 1 includes a permanent magnet 15 having pole pieces 16 connected thereto about which are positioned coils 17. The two coils 17 are connected in series to provide pulses to transistor 21 as will be explained. The permanent magnet and coil assembly are mounted on a dished plate 18 which may be similar to the type used to support the contacts in standard automotive distributors. A toothed magnetic wheel or armature 19 is mounted for rotation so that the teeth 20 thereof pass by and in close proximity to the ends of the pole pieces 16. Armature 19 may be driven by the distributor shaft 43 to rotate with the rotor 13 as will be further explained. The elements just described including magnet 15 and armature 19 are intended, as shown assembled in FIG. 1, to illustrate the appearance of the mechanism when distributor cap 41 and rotor 13 are removed. (See FIG. 2.)

As stated above, the coils 17 are connected in a circuit to provide pulses to the input of transistor 21. Coils 17 are connected between the emitter and base electrodes of transistor 21. Bias potential is applied to the emitter electrode of transistor 21 from the bias supply line through the voltage divider circuit including coils 17 and resistor 24 to the base electrode of this transistor. This bias potential causes the transistor 21 to be normally conducting.

The collector electrode of transistor 21 is connected to transformer 25 which applies the pulses from the transistor 21 to the transistor 22. Bias is applied to transistor 22 to the emitter electrode thereof and through the secondary winding of transformer 25 to the base electrode. A feedback connection is provided from the collector of transistor 22, through a resistor 23, to the base of transistor 21. Transistor 22 is normally nonconducting and is rendered conducting by the pulse applied between the base and emitter electrodes thereof. Transistor 22 is cut off at the end of the pulse to develop a sharp pulse in the primary winding 31 of transformer 32. This pulse is stepped up in the high voltage ignition coil or secondary winding 33 of transformer 32 and applied to the moving distributor contact 12. The pulse is thereby selectively applied to the terminals 11 of the cylinders of the internal combustion engine.

It will be apparent from FIG. 1 that when armature 19 is positioned so that a tooth 21 thereof is between the ends of the pole pieces 16, the flux through the coils 17 will be minimum. As the armature rotates, so that the teeth 19 first approach, then become aligned with, and finally pass away from the ends of pole pieces 16, the value of the flux through coil 17 will first increase to a maximum value and then decrease to the minimum. This change in flux through the inductance coils 17 as armature 19 rotates will develop voltage across the coils. Because of the conduction of the transistor 21, the voltage applied between the base and emitter will not rise during the first half of the cycle, but the negative portion of the cycle of the voltage produced in coil 17 will cause the transistor 21 to be cut off. Because it is as the flux is decreasing that the negative portion of the voltage cycle is produced in coil 17, electrical delay results.

The voltage between the collector of transistor 21 and ground will be positive when the transistor conducts and will swing negative when the transistor is cut off. This voltage is applied through transformer 25 between the base and emitter circuit of transistor 22 and is reversed .in phase to provide a positive pulse thereto. As previously stated, transistor 22 is normally nonconducting. However, the voltage applied between the base and emitter electrodes thereof during the second half of the cycle will cause the transistor 22 to be driven first to saturation and then back to cut off to provide a sharp pulse in the primary winding 31 of transformer 32. This pulse is stepped up in the transformer 32 to provide an extremely high voltage at the movable distributor 12.

The dished plate 18A of the pulsing unit on which the coils 17 are mounted is commonly called the advance plate of the distributor and may be advanced or retarded with respect to the rotating disc 19. This operation may be controlled by a vacuum advance, as indicated by drive rod 35, and regulates the time of firing of the cylinder with respect to the movement of the pistons thereon. The vacuum advance may operate from the butterfly valve in the carburetor of the internal combustion engine so that an immediate advance will take place when a sudden variation in throttle opening occurs to compensate for the greater amount of fuel entering the cylinders. As the vacuum decreases at the butterfly valve, the advance plate will gradually return to its original position. However, since the engine speed is increasing, the centrifugal advance mechanism, which will be explained below, compensates to effectively maintain the advance. Thus, the vacuum advance serves as a supplement to the centrifugal advance. Referring now to FIGS. 2 and 3, a distributor shaft 43, which may be driven by the engine 10, extends through a lower housing 45, and rotates in a counter clockwise direction when viewed from the top. Distributor cap- 41 clamps to lower housing 45 and contains a rotor contact 48 which is connected to the secondary winding 33 of transformer 32 as shown in FIG. 1. A sleeve 47 is concentrically mounted on shaft 43 for the driving rotor 13 directly fixed to its upper end. Contacts 14 extend inwardly and down from distributor cap 41 and are positioned so that distributor contact 12 will pass extremely close thereto. Thus, rotor 13, containing distributor contact 12, rotates with the sleeve 47 in the direction shown by the arrow in FIG. 1 to selectively complete a circuit to contacts 14 and conduct pulses thereto. Also fixed to sleeve 47 is rotor plate 49 which, as shown in FIG. 3, contains a pair of elongated slots 51 which are disposed transversely to a radius of plate 49.

The armature 19, of the pulsing unit which has been described, is fixed on a second sleeve 53 which is mounted concentrically on sleeve 47. Also fixed to sleeve 53 is armature plate 55 which, as shown in FIG. 1, contains a pairs of elongated slots 57 which are disposed transversely to a radius of plate 55. Plates 49 and 55 are mounted on their respective sleeves in parallel planes and are so positioned that slots 57 and 51 are transverse to one another in the manner shown in FIG. 3. That is, the slots 51 are slanted toward the direction of rotation of the shaft 43, while slots 57 are slanted away from said direction of rotation.

A drive plate 59 is fixed to shaft 43 and is rotatable therewith. Pivotally mounted on plate 59 are a pair of flyweights 61 and 63 which are spring biased to an inward position by means of'coil springs 65 and 67 fixed to posts 69 and 71 extending from plate 59. Flyweights 61 and 63 have drive posts 73 and 75 respectively extending therefrom. These drive posts extend through slots 51 in plate 49 and through slots 57 in plate 55, and provide a driving contact with the plates causing sleeves 47 and 53 and therefore armature 19 and rotor 13 to rotate with shaft 43.

As the speed of shaft 43 increases, flyweights 61 and 63 will pivot outwardly due to centrifugal force against the bias of springs 65 and 67 respectively. This causes movement of posts 73 and 75 in slots 51 and 57, providing a cam type action to displace plates 49 and 55 respectively. Sleeve 53 and armature 19 are thereby advanced angularly with respect to the shaft 43, while at the same time sleeve 47 and rotor 13 are retarded angularly with respect to the shaft 43. The result is that the coils 17 will produce a pulse proportionally sooner, and at the same time rotary contact 12 is maintained in substantial alignment with the proper one of contacts 14. Greater advance is possible than in previous systems because the rotor 13 is retarded to offset the effect thereon of advancing armature 19, thereby preventing the spark from jumping from distributor contact 12 to the wrong one of the contacts 14. The angular deviation of slots 51 and 57 from the true radii of their respective plots determines to a great extent the rate and amount of advance and retardation possible in the mechanism. The other major factors bearing on the rate and amount of advance and retardation for given speeds are the resilience of springs 65 and 67 and the length of slots 51 and 57.

It may therefore be seen that the invention provides an improved low cost distributor and timer unit in which the rotary member operating the pulsing unit may be advanced while at the same time the distributor rotor may be retarded, thereby making it possible to use a substantially greater advance than prior units.

I claim:

1. An ignition system for use with an internal combustion engine having ignition means, including in combination, a rotary drive shaft, pulse producing means including a rotary member for operating said pulse producing means, rotary conductor means electrically connected to said pulse producing means, and speed responsive means mechanically coupling said rotary member and said rotary conductor means to said shaft for both angularly advancing said rotary member with respect to said shaft and angularly retarding said rotary conductor means with respect to said shaft as the speed of rotation of said shaft increases.

2. An ignition system for use with an internal combustion engine having ignition means, including in combination, a rotary drive shaft, pulse producing means having a rotary member and a pulse generating unit operable thereby, said pulse generating unit having inductance means introducing a time delay of said pulse with respect to the angular position of said rotary drive shaft, rotary conductor means electrically connected to said pulse producing means, and speed responsive means mechanically coupling said rotary member and said rotary conductor means to said shaft for both angularly advancing said rotary member with respect to said shaft and angularly retarding said rotary conductor means with respect to said shaft as the speed of rotation of said shaft increases.

3. An ignition system for use with an internal combustion engine having ignition means, including in combination, a rotary drive shaft, pulse producing means including a rotary member for operating said pulse producing means, said pulse producing means further including first and second inductively coupled switching transistors and a high voltage ignition coil inductively coupled to the output of said second transistor, said first and second transistors operating to induce a high voltage pulse in said ignition coil when said second transistor is first driven to saturation and then cut off, said pulse producing means further including an inductive pulse generating unit supplying pulses to said first transistor to control operation of said second transistor, said pulses being delayed in time by said inductive pulse generating unit with respect to the angular position of said rotary drive shaft, rotary conductor means electrically connected to said igition coil, and speed responsive means mechanically coupling said rotary member and said rotary conductor means to said shaft for both angularly advancing said rotary member with respect to said shaft and angularly retarding said rotary conductor means with respect to said shaft as the speed of rotation of said shaft increases.

4. An ignition system for use with an internal combustion engine having ignition means, including in combination, a rotary drive shaft, pulse producing means including a rotary member for operating said pulse producing means, rotary conductor means electrically connected to said pulse producing means, speed responsive means fixed to said rotary drive shaft and radially displaceable away from the axis of said drive shaft, camming means fixed to said speed responsive means, and first and second cam follower means having transversely disposed surfaces engageable by said camming means to convert said radial movement of said speed responsive means to angular displacement of said rotary member and said rotary conductor means respectively for both angularly advancing said rotary member with respect to said shaft and angularly retarding said rotary conductor means with respect to said shaft as the speed of rotation of said shaft increases.

5. An ignition system for use with an internal combustion engine having a plurality of cylinders with associated ignition means, including in combination, a rotary drive shaft, pulse producing means including a rotary member for operating said pulse producing means, a plurality of contacts arranged in a circular order and connected to the ignition means of the engine, rotary conductor means electrically connected to said pulse producing means for selectively applying ignition pulses to said contacts for application to the ignition means of the engine, and means responsive to centrifugal force coupling said rotary member and said rotary conductor means to said shaft, said means including a pair ofrotary plates coupled to said rotary member and said rotary conductor means respectively for displacing same, so that said means will angularly advance said member with respect to said shaft and angularly retard said rotary conductor means with respect to said shaft as the speed of rotation of said shaft increases.

6. An ignition system for use with an internal combustion engine having ignition means, including in combination, a rotary drive shaft, magnetic pulse producing means including a rotary member for operating said pulse producing means, rotary conductor means electrically connected to said magnetic pulse producing means for selectively applying pulses to the ignition means of the engine, a first rotatable sleeve concentrically mounted on said shaft and fixed to said rotary conductor means for driving the same, a second rotatable sleeve concentrically mounted on said first rotatable sleeve and fixed to said rotary member for driving the same, and a centrifugal force responsive mechanism including a base plate fixed to said shaft and a pair of rotary plates respectively fixed to said first and second sleeves, said mechanism further including pivotal means coupling said base plate to said rotary plates, said pivotal means being displaceable by centrifugal force acting thereon due to increased rotational speed to angularly advance said second sleeve and said rotary member with respect to said shaft and angularly retard said first sleeve and said rotary conductor means with respect to said shaft as the speed of rotation of said shaft increases.

7. An ignition system for use with an internal combustion engine having ignition means, including in combination, a rotary drive shaft, magnetic pulse producing means including a rotary member for operating said pulse producing means, a plurality of contacts arranged in a circular order and connected to the ignition means of the engine, rotary conductor means electrically connected to said pulse producing means for selectively applying ignition pulses to said contacts for application to the ignition means of the engine, a first rotatable sleeve concentrically mounted on said shaft and fixed to said rotary conductor means for driving the same, a second rotatable sleeve concentrically mounted on said first rotatable sleeve and fixed to said rotary member for driving the same, first and second rotary plates, each having a pair of elongated slots formed therein disposed transversely to the radii thereof, said first rotary plate being fixed to said first sleeve and said second rotary plate being fixed to said second sleeve with said rotary plates being disposed in parallel planes, said elongated slot on said first rotary plate being disposed transversely of said elongated slot on said second rotary plate, a base plate fixed to said shaft and having a pair of pivotal fiyweights mounted thereon, each of said flyweights having a driving extension thereon extending through one of said elongated slots on said first rotary plate and one of said elongated slots References Cited in the file of this patent UNITED STATES PATENTS 2,773,140 Guernsey et a1. Dec. 4, 1956 2,918,911 Guiot Dec. 29, 1959 3,073,879 Straub Jan. 15, 1963

Claims (1)

1. AN IGNITION SYSTEM FOR USE WITH AN INTERNAL COMBUSTION ENGINE HAVING IGNITION MEANS, INCLUDING IN COMBINATION, A ROTARY DRIVE SHAFT, PULSE PRODUCING MEANS INCLUDING A ROTARY MEMBER FOR OPERATING SAID PULSE PRODUCING MEANS, ROTARY CONDUCTOR MEANS ELECTRICALLY CONNECTED TO SAID PULSE PRODUCING MEANS, AND SPEED RESPONSIVE MEANS MECHANICALLY COUPLING SAID ROTARY MEMBER AND SAID ROTARY CONDUCTOR MEANS TO SAID SHAFT FOR BOTH ANGULARLY ADVANCING SAID ROTARY MEMBER WITH RESPECT TO SAID SHAFT AND ANGULARLY RETARDING SAID ROTARY CONDUCTOR MEANS WITH RESPECT TO SAID SHAFT AS THE SPEED OF ROTATION OF SAID SHAFT INCREASES.

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