US2306889A - Ignition timer - Google Patents

Description

Dec. 29, 1942. M, MALLORY IGNITION TIMER Original Filed Jan. 4, 1937 '.3 Sheets-Sheet 1 1M. MALLRY IGNITION TIMER f Original Filed Jan. 4, 1937 3 Sheets-Sheet 2 Dgc. 29, 1942. M. MALLORY IGNITION TIMER Original 'Filed Jan. 4, 1937 3 Sheets-Sheet 3 Patented Dec. 29, 1942 UNITED STATES PATENT OFFICE 2,306,889 v IGNITION TIMER Marion Mallory, Detroit, Mich.

Original application January 4, 1937, Serial No. 119,006. Divided and this application October 4, 1940, Serial No. 359,771

Claims. .(Cl. 200-31) This invention relates to ignition timers for in ternal combustion engines and more especially to the automatic control thereof in accordance with the speed and load. This application is a division of application Serial No. 119,006, filed January n 4, 1937, abandoned March l, 1941.

For smooth idling, an extreme retardation of the timing is necessary, but upon a slight opening of the throttle, there should be an appreciable immediate advance of the timing. Following this, there should be a further gradual advance as the speed increases, but when the engine is working under full load with wide open throttle at either low or high speeds, it is desirable to retard the advance to some extent to prevent detonation.

It has heretofore been proposed to use centrifugal means to'advance the spark in proportion to the speed, and supplemental spark advancing means controlled by the suction of the engine intake. In the operation of devices of this kind as heretofore proposed however, either the suction is not immediately effective to advance the spark as soon as the throttle starts to open, or it is not rendered ineffective when the throttle is wide open.

With the above facts in mind, it is an object of the present invention to provide, in addition to a centrifugal spark advance, a supplemental suction controlled spark advancing means and means in the nature of a suction controlled valve to render the suction controlled spark advancing means eective at the proper time. This supplemental spark advancing means is connected into the intake manifold but is out oi therefrom at the proper time by the valve, which is connected to the intake on the atmospheric side of the throttle valve when the latter is closed for idling. As soon as the throttle starts to open, the suction controlled valve is subjected to suction from the inflowing fuel and, since it is normally held closed by a light spring, it will immediately open, thus subjecting the spark control to the action of the high vacuum of the manifold, which advances the spark. With the throttle wide open at either high or low speeds, the suction may be high enough to operate the suction controlled spark advance. However, the suction in the intake passageway will be insuflicient to open the valve to permit the vacuum spark control to advance the spark.

It is also an object of the invention to provide convenient means to easily adjust the maximum range of speed governor advance, the rate of such advance, andthe maximum range of suction controlled advance, so that these characteristics of the spark timing may be properly set for the individual timer or the individual engine with which the timer is used.

The above and other objects and advantages of the invention will be more particularly explained in connection with the accompanying drawings, in which Fig. 1 is a horizontal section through the timer housing above the brake plate, showing the suction controlled valve in a position to cut ofi the vacuum between the brake and the manifold, allowing the brake to engage and hold the timer in a retard position.

Fig. 2 is a sectional view showing the suction control valve of Fig. 1 in a position to connect the brake with the intake manifold vacuum for advancing the spark.

Fig. 3 is a vertical section through the timer housing, the circuit breakers and springs being omitted.

Fig. 4 is a plan view of the circuit breakers and plate.

Fig. 5 is a section taken on the line 5-5 of Fig. 3.

Fig. 6 is a section taken on the line E-G of Fig. 3.

Figs. 7 and 8 are charts representing the governor curves resulting from Various adjustments of the timer.

As illustrated in Figs. 1, 2 and 3, the invention is associated with an engine intake manifold l0 having a fuel intake passageway I l with a throttle valve I2 therein. The housing 23 is formed with a shank 33 which is lined with a bushing 34 to provide a bearing for the timer shaft 35 adapted to be driven from the engine. The shaft 35 has a reduced extension 36 on which is mounted a sleeve 31 carrying the circuit breaker cam 38. A circuit breaker plate 39 ts into the housing 23 and is secured by insulated screws 40 and 4|, to which the circuit breaker springs 42 and 43 are also secured. The terminal screws 40 and 4I are electrically connected by an insulated conductor 44 and the inner ends of the springs 42 and 43, which constitute parts of the primary circuit, are secured to overlapping circuits breakers 45 and 45. Since the mountings of the latter do not constitute a part of the present invention, it is not necessary to describe the same here in detail.

The sleeve 3l is formed with a flange 5G to which a governor plate 55 is clamped by means of a clamping member 51 and screws 53. A drive plate t9 is iiXed to the shaft 35. A circular brake plate 26 floats on the timer shaft 35 between the plates 49 and 55.

The plate 55 and circuit breaker cam 38 are adapted to be advanced with reference to the brake plate 26 by centrifugal governor mechanism, which may be termed the primary timing control and which will be hereinafter more particularly described.

The brake plate 26 is adapted to be held in an advanced position with reference to the drive plate 49 by a spring 52, except when it is held in retard position by the engagement of a brake 25 with its periphery. 'I'his brake is carried by a piston 24 which operates in a cylinder 22 connected to the timer housing 23. A spring 21 holds the brake in engagement with the plate 426 until there is suflicient vacuum developed in the cylinder to overcome the action ofthe spring, thereby retracting the piston and permitting an immediate advance of the plate 26 with a corresponding advance of the timing. This may be termed the supplemental or vacuum timing control.

The vacuum is developed in the cylinder 22 through a conduit I3 which is connected through a valve casing I4 and conduit I5 to the manifold I8. Communication between the conduits I3 and I5 is adapted to be cut off by a valve I6, which is normally held closed by a spring I1. The end of the casing beneath the valve has a passageway I8 leading into the intake II immediately above the throttle valve I2 when the latter is in closed or idling position. A vent I9 in the other end of the casing I4 permits the valve to be opened by suction through the passageway I8 in opposition to the spring I1. An annular groove 2,8 in the valve I6 is at all times in communication with the conduit I3, Another annular groove 2l Ybleeds into the passageway I8. Thus the valve is prevented from becoming vacuum-locked against the casing wall.

The centrifugal governor mechanism comprises two governor weights 41 and 48. One of these weights,' as 48, is pivotally mounted on a pin 53 secured to the plate 26. The other weight 41 is pivotally mounted on a pin 54 which projects downwardly from the plate 55 secured to the sleeve 31. As the weights fly outwardly about their pivots 5d and 53 under the influence of centrifugal force, the edges 59 roll on each other, forcing the pivots 54 and 53 farther apart and causing an advance of the plate 55, sleeve 31 and circuit breaker cam 38 with reference to the plate 25. The extreme outward movement of the Weights 41 and 48 is limited by their engagement with the pins 68 and 6I secured in the respective plates 55 and 26.

The characteristics of the spark advance curve necessary for the most economical operation vary widely in different cars and different engines, and even in the same engine at different periods of its life. This invention therefore p-rovides for universal adjustment of these characteristics.

In order to adjustably limit the maximum advance of the governor plate 55 and cam 38 with reference to the plate 26, as controlled by the governor weights 41 and 48, an arm 68 is mounted for pivotal adjustment about the shaft 36 and is secured in its adjusted position by a clamping screw 65, which extends through a slot 10 in said arm into the plate 26. The cam edge 1I of the arm 68 is adapted to engage the downwardly projecting end of the pin 54, which extends into a slot 12in the plate 26, and thereby progressively decreases the maximum range of advance of the plate 55 with reference to the plate 26, as the arm is adjusted towardthe left. The

position of the adjustment is indicated fon the 76 scale 13 by the pointer 14 on the end of the arm 68,

The action of the governor weights 41 and 48 in advancing the plate 55 is resisted by a spring 15, which is so mounted that the point where the advance begins and the ratio of such advance to the increase in speed may be adjusted. One end of the spring 15 is connected to a pin 16 secured to an arm 11 which is mounted for adjustment about a pivot pin 18secured to the under side of the plate. The pin 16 projects upwardly through an arcuate slot 1S in the plate and the .arm 11 is secured in adjusted position by a clamping screw which extends through a slot 8| into the arm. The other end of the spring 15 is connected to a pin S2 on an arm 83 which is pivotally mounted on the pin 18. An arm S4 is mounted for pivotal adjustment about a pin on the plate 55 and is secured in adjusted position by a clamping Screw 86, which extends through a slot 81 in said arm and into the plate 55. A pin 88 secured to the arm 84 engages an arcuate slot 89 in the arm 83.

Adjustment of the arm B4 about its pivot 85 Varies the position of the pin 88 in the slot 89 and the consequent leverage of the arm 83 about its pivot 18', when` the governor weights act to advance the plate 55 in opposition to the resistance of the governor spring 15 transmitted through the pin 82, arm 83, pin 88 and arm 84 to the plate 55. This adjustment therefore varies the tension of the governor spring and the ratio of the speed controlled advance of the timing as compared to the speed.

Adjustment of the arm 11 about its pivot 18 toward the outer edge of the plate 26 increases the tension on the governor spring 15.

Adjustment of the arm 68 about the shaft 36 as va center causes said arm to cover more or less of the end of the slot 12, into which the pinj54 projects, and the engagement of the pin with the edg'e1l `of the arm variably limits'the vmaximum advance ofthe plate 55 and consequently the maximum speed controlled advance of the spark.

The brake plate 26 is held adjacent the drive plate 49 by two pins 5,8 and 5i!a which are inserted through slots 5I and 5Ia in the brake plate and secured in the drive plate. These slots therefore limit the rotational displacement ofthe plate 26 with reference to the 'plate 49. In order to adjustably limit the maximum relative advance of the plate 26, and consequently the vacuum controlled spark advance, an arm 62 is mounted for adjustment about a pivot 63 on the plate 26 and is secured in adjusted position by a clamping screw 64 which extends through a slot 65 into said plate. The inclined-end 66 of the arm 62 is adapted` to engage the head of the pin 58 and thereby progressively limit the effective length of the slot 5I. The maximum advance-of the bra-ke Aplate. 2,6,- thus limited, is indicated by the point Yof the arm 62 ron the scale 61.

In theoperation of the vacuum controlled advance, the valve I6 is .closed whenever the throttle valve isV closed. In the structure illustratedY in Fig. 1, there willbe under such conditions no vacuum in the cylinder 22, the brake 25 will en-v gage the brake .plate-,26, the latter will be held -in retarded position, and there will be an extremecomparatively high vacuum in the manifold l0, which will immediately cause a maximum vacuum advance of the spark. This advance may be in the neighborhood of or 15, depending upon the adjustment of the arm 62. This vacuum advance is added to the speed controlled spark advance which increases gradually through a predetermined range of speed and which is effected by advancing the circuit breaker cam with respect to the brake plate 26.

The strength of the spring I1 is so chosen that it overcomes the vacuum induced by the flow through the open intake passageway at a speed in the neighborhood, say, of 50 miles per hour. This renders the vacuum spark advancing means ineffective, so that the spark advance is then entirely dependent upon the centrifugal governor. This moderate recession from the maximum spark advance is desirable at the highest speeds to prevent detonaton.

Adjustment of the arm 62 about its pivot 63 causes the end 66 of the arm to variably limit the range of movement of the brake plate 25 with reference to the plate 49, thereby adjustably limiting the possible advance of the spark when the piston 24 is retracted by the vacuum in the manifold.

From the foregoing description, it will be seen that I have provided means to advance the timing in accordance with speed throughout a predetermined adjustable range and, in addition thereto, improved vacuum controlled means to cause a predetermined sparkadvance upon a change from idling to low speed travel, this vacuum controlled means being ineffective for advancing the spark at the highest speeds, or when the engine is working under la heavy load with open throttle.

The timer also has all the adjustments necessary to secure the desired spark advance curve for the most satisfactory performance of any given engine, as illustrated in Figs. 7 and 8. As above stated, the desired rate of spark advance by the governor, as compared to increased speed of the engine, is obtained by variation in the tension of the governor spring 75, which is effected by adjusting the arm 84. Each graduation on the edge of the slot 89 represents a difference of approximately 400 R. P. M. on the governor advance curve. These curves for different adjustments are represented at A, B, C, D, E, F, in Fig.

7. When adjusting the governor for a smaller advance, such as or less, to finish at 4000 R. P. M. or later as illustrated by governor advance curves G, H, I, J, K, L, it may be necessary to place additional tension on the governor spring 'i5 by adjusting the arm 'l1 toward the outer edge of the plate, as above explained. Curves A, B and C may be produced by using an 8-ounce governor spring. Curves D to L inclusive may be produced by using a 16ounce governor spring.

When the engine is operating under full throttle and heavy load and the vacuum in the intake manifold drops to approximately 12 mercury or under, the spring 21 will cause the brake 25 to engage the plate 26, bringing it into retard position and effecting a like retardation of the centrifugal governor assembly and circuit breaker cam. The governor curve Will then be similar to that shown at A. As the engine speed increases, or the throttle is partly closed, the vaeuum in the intake manifold will build up to a point in excess of 12" mercury, at which point the piston 24 Will be retracted, releasing the brake plate 26, whereupon the governor drive spring 52 will immediately advance the brake plate and the governor and cam assemblies. The governor will then produce a light load curve similar to that shown by the broken line A', which has for illustration been set 10 higher than the load curve A.

On some engines the initial timing is set very close to top dead center. With this setting a rapid intermediate advance of the governor is necessary from approximately 400 R. P. M. to 800 R. P. M. of the engine, as shown by curves P, Q, R, S, on Fig. 8. To produce these curves, it is necessary to use a special governor spring lever adjustment arm 84, stamped 6, 10, 12o or 14, indicating the point at which the slower advance of the timing begins. With this adjustment arm, a 2li-ounce governor spring should be used. The normal position of the spring post I6 is in the end of the slot 19 nearest the center of the plat-e. In case the governor advances too fast through the lower speed range, resulting in a slight spark knock, the spring post 'I6 should be adjusted toward the other end of the slot.

While the suction control of the spark advance is shown in connection with a brake adapted to be applied to a plate that carries the timing mechanism, it will be apparent that the same suction control may be used with any other type of timing mechanism, whether the spark is advanced by moving the housing, the circuit breaker plate, circuit breaker cam, or the complete governor assembly. Various other details may also be modified without departing from the scope of the invention as defined in the appended claims.

I claim:

1. An ignition timer for an internal combustion engine comprising a rotatable timer shaft, a circuit breaker cam mounted on and driven by said shaft, said cam adapted to have a limited relative rotative movement on said shaft, centrifugal means for advancing the cam on said timer shaft, and a plate also mounted on said shaft and adapted to have a limited relative rotative movement thereon, said cam and plate also adapted to have a limited relative rotative movement on said shaft with respect to each other, and means connecting said plate and cam whereby advancing said plate on said shaft effects a corresponding advance of said cam on said shaft, said centrifugal means advancing said cam on said shaft independently of said plate.

2. An ignition timer for an internal combustion engine comprising a rotatable timer shaft, a circuit breaker cam mounted on and driven by said shaft, said cam adapted to have a limited relative rotative movement on said shaft, centrifugal means for advancing the cam on said timer shaft, and a plate also mounted on said shaft and adapted to have a limited relative rotative movement thereon, said cam and plate also adapted to have a limited relative rotative movement on said shaft with respect to each other, and means connecting said plate and cam whereby advancing said plate on said shaft effects a corresponding advance of said cam on said shaft, said centrifugal means advancing said cam on said shaft independently of said plate and independently of said below-mentioned suction controlled means, and suction controlled means for advancing said plate on said shaft.

3. An ignition timer for an internal combustion engine comprising a rotatable driving member, a circuit breaker member mounted on and driven by said driving member and having a limited rotative movement relative to said driving member, a plate also mounted on said driving member and having a limited rotative movementv relative to said driving member, said circuit breaker member also having a limited rotative movement relative to said plate, centrifugal means for advancing the circuit breaker member on said shaft and with respect to said plate and independently of said below-mentioned suction controlled means, and suction controlled means for advancing both the said plate and the circuit breaker member as a unit on said driving member.

4. An ignition timer for an internal combustion engine comprising a rotatable timer shaft, a circuit breaker cam mounted on and driven by said timer shaft and having a limited rotative movement relative to said timer shaft, a plate also mounted on said timer shaft and having a limited rotative movement relative to said timer shaft, said circuit breaker cam also having a limited rotative movement relative to said plate, centrifugal means for advancing the circuit breaker cam on said shaft and with respect to said plate and independently of said below-mentioned suction controlled means, and suction controlled means for advancing both the said plate and the circuit breaker cam as a unit on said timer shaft.

v5. An ignition timer for an'internal combles.- tion engine comprising a timer shaft, a plate rigidly connected thereto, a second plate having an ignitioncam mounted thereon, the second plate being free to oscillate a limited distance on said timer shaft, a spring connected between the i-lrst and second named plates which tends to hold'the second named plate to its limited movement in the direction of rotation of timer shaft, a friction brake to engage the se-cond named plate and overcome said spring to hold the second named plate and said ignition cam to its limited movement in a direction opposite to that of said timer shaft, a governor Weight pivetedly mounted on second named plate, a third plate and a cam mounted on said plate, both cam and said third plate being free to oscillate on said timer shaft, a second governor Weight pivotedly mounted on the third named plate, said second governor weight engaging with the first governor weight to advance the third named plate and cam as the speed of the said timer shaft in creases, and spring meansV connecting the second and third named plates together to resist the power of the centrifugal governor Weights.

MARION MALLORY.

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