US1989941A - Method of and means for starting an internal combustion engine - Google Patents

Description

Feb. 5, 1935.

METHOD OF AND MEANS FOR STARTING A Filed Apri B. L. M LANE N INTERNAL COMBUSTION ENGINE 1 1 1930 2 Sheets-Sheet 1 FIG. 10.

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BERTUS L. N LANE.

Feb. 5, 1935. B, L, MCLANE 1,999,941

METHOD OF AND MEANS FOR STARTING AN INTERNAL COMBUSTION ENGINE Filed April 14, 1930 2 Sheets-Sheet 2 BERTUS L. M LANE INVENTOR BY 'aanu a manv.

ATTORN EY Patented Feb. 5, 1935 UNITED STATES PATENT OFFICE METHOD OF AND MEANS FOR STARTING AN INTERNAL COMBUSTION ENGINE Bertus L. McLane, Tulsa, Okla. 7 Application April 14, 1930, Serial No. 444,133

7 Claims.

tion the type of engine shown is a two stroke cycle internal combustion enginebut it is to be understood that my device is also applicable to a four stroke cycle engine. The impulse coupler is located in the drive between the engine shaft and the magneto which is used in producing the spark for the engine; said coupling being so constructed as to operate on the backward rocking of the flywheel of the engine and thereafter, when the engine is-normally running, as a normal clutch to actuate the magneto on the forward drive.

I realize that it is old to use accelerating means to rapidly rotate the armature of a magneto through its-magnetic field when'the engine is.

being started in order to produce a fat spark, such a device being called an impulse coupler and therefore I do not claim this broadly but rather my invention lies in the application of such a device in a novel manner.

Magnetos are widely used as ignition means on large gas engines, such as those used in the oil fields as prime movers for powers and the like and oftentimes considerable difficulty is had in starting them. Unless compressed air or the like is available to start this type of engine, under the present practice, one must rock the flywheel backwards toward compression and simply allow the spark to occur at a more or less opportune time.

One of the primary aims of my invention is to control the position and the intensity of this spark.

I control the intensity of the spark by breaking the primary circuit of the armature when the flux lines therein are at a maximum. In order to accomplish'this the permanent magnets forming the field must "be rotated about the axis of the magneto or rather its armature. Previous to my invention there has been no occasion to so rotate the permanent field in engine starting equipment because the electric currents were generated by rotation of the magneto in a single direction. That is to say, even though the flywheel and engine were manually turned backwards (in starting) through part of a revolution, nevertheless, the winding up I of the magneto through its impulse coupler, was such as to rotate it in the usual direction.

The just referred to type of coupler is far from satisfactory as the spark within the cylinder occurs only after the piston has reached its most rearward position and is returning therefrom. And the return must be of such duration as to wind up and also trip the coupler. This is due to the fact that the impulse coupler does not release or trip until the engine starts in its normal running direction due to the expansion of the gases which were compressed by the reverse manual rotation of the engine. Thus a delayed explosion is had which has less time to act upon or push against the piston of the engine and furthermore its force or effect is diminished due to the lesser compression, such lesser compression slowing down the propagation of the burning gases.

In my improved system I provide mechanism which will create the explosion within the cylin' der just before the piston starts to return. That is to say, the impulse coupler trips on the reverse movement of the engine. Consequently, the above two defects are overcome and the combustion within the cylinder is propagated rapidly. As engines wear the positions of the points at which the most efficient explosion occurs may change slightly but this can be readily taken care of by rocking the magneto on its axis to a slightly different point. For instance, when the engine iscomparatively new and stiff the flywheel cannot be rocked rearwardly as far as it can after it has been in use for a year or so and in order to take care of the latter condition it is necessary to manually rotate the magneto farther from its normal running condition than otherwise in order that the flux field may be at a maximum when the primary circuit is broken as will be understood by those skilled in this art.

Briefly described, my invention may be said to primarily reside in two main features, first, the impulse coupler which not only winds up but which also trips on reverse rotation, and, second, 'means to adjustably rotate the magneto about its armature axis. It should be appreciated that the above two features are somewhat interrelated because it is the fact that the tripping of the impulse coupler occurs on what is normally a reverse movement which requires that the rotatable adjustment be had in order that the mechanism operate efficiently.

Other objects of this invention will be set forth in the following description and drawings, which illustrate a preferred embodiment of this invention, it being understood that the above general statement is intended merely to generally explain the same and not to limit it in any manner.

In the drawings:

Fig. 1 is a diagrammatic view, partly in section, illustrating the application of my invention to an internal combustion engine.

Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1.

Fig. 3 is a sectional view taken along the line 3-3 of Fig. 1. Fig. 4 is a view in cross section looking from the magneto towards the impulse coupling, such view being taken along the line 4-4 of Fig. 1.

Fig. 5 is a longitudinal sectional View, this being taken along the line VV of Fig. 4. The several parts are shown in separated relationship in order to expedite the showing.

Fig. 6 is a View looking in the direction indicated by the arrow A, Fig. 5, the dotted lines indicating the projection of the pawl carrier, the pawl itself being omitted. The arrow B indicates the normal direction of engine rotation, such being clockwise as in Fig. 4:.

Fig. '7 is a sectional View taken along the line 77 of Fig. 1, the stationary ring member being omitted. The dotted line showing, as indicated at C, shows the position of one of the lugs during the winding movement of the spring of the coupler and immediately preceding its release.

Fig. 8 is a reduced View of the magneto and its mounting, this View being taken as indicated by the arrow W in Fig. 1.

Fig. 9 is a view similar to Fig. 2 but showing the positioning of the several parts at the instant of starting.

Fig. 10 is a view similar to Fig. 3 but showing the permanent magnetic field shifted so that a maximum of flux lines will be broken by the cessation of the electric current which occurs at the instant of starting.

Fig. 11 shows the approximate position of the piston within its cylinder at the instant of start- Similar numerals and similar letters represent similar parts throughout the several views.

Referring particularly to Fig. 1, E indicates the crankshaft or its axis of an engine having a piston P connected to the shaft by a pitman or connecting rod R.

The crankshaft E drives a magneto shaft M through the gears 40 and 20, the gear 40, attached to the crankshaft, being of twice the diameter of the other gear whereby the magneto shaft rotates at twice the speed of the crankshaft.

The stationary interrupter ring T has interior cams 8 and 9. This ring is mounted in a housing whereby it is rigidly attached to the magneto frame so as to move bodily therewith as is clearly shown in Fig. 1. The short cam 8 serves as a relief cam while the other earn 9 serves a double function. One of its ends, as shown in Fig. 2, serves to initiate the running spark, while the other end, as shown in Fig. 9, causes or actuates the starting spark.

Numeral 10 designates the field magnet construction which has poles marked N and S. An armature G rotates between these poles. A primary winding K on the armature induces high voltage in the secondary winding L and a suitable distributor or the like (not shown) is provided to lead the current to the spark plug or the like in order to fire or ignite the explosive mixture.

As shown in Fig. 1, the piston is at top dead center and the explosion of the gaseous fuel occurs at substantially this point. The circuit breaking arm mechanism, see Figs. 2 and 9, is indicated generally by numeral 1 and it is to be understood that Whenever the arm proper rides upon the cams 8 and 9 that the primary circuit is broken.

The showing of Fig. 2 corresponds with that of Fig. 1, that is, the arm of the breaker mechanism rides upon the end of the cam 9 as indicated at 2 and this causes the production of the running spark.

The showing of Fig. 3 also corresponds with that of Fig. 1 and the position of the armature G is such, with reference to the poles N and S of the field, as to produce a maximum spark. That is, the armature G is well past the geometrical pole axis so as to be in the maximum field flux density. In other words, with the rotation of the armature as indicated by the arrow, the interruption of the primary circuit should occur as shown in order to obtain the best results.

The magneto shaft and the attached breaker arm rotates at twice the speed of the crankshaft and thus when the arm rides upon the relief cam 8, as indicated at 3, the piston is at a halfway point in its power stroke, when the arm reaches the point 2 again another spark is produced and when the arm again reaches the point 3 yet another spark is had, this latter spark being grounded out in any suitable manner.

Figs. 9, 19 and 11 show the positions of the several units when starting with my improved device or system. As shown, the interrupter or breaker mechanism 1 is caused to rotate in the direction of the arrow as shown in Fig. 9 due to the manual reverse rotation of the engine. The showing of Fig. 11 is typical of the position to which the piston might be manually moved, it being understood that as the engine loses compression the farther counterclockwise the flywheel can be tinned. 11, the direction of normal rotation of the engine is clockwise. As previously stated, the breaker arm mechanism is at 2, see Fig. 2, when the piston is at bottom dead center and as the flywheel is rotated rearwardly somewhat exceeding the breaker arm will move in the direction of the arrow, see Fig. 9, about 186 or until it reaches the point 4.

As shown in Fig. 10, the field is positioned so that the armature G has a maximum flux density flowing therein and thus a fat spark is obtained thus facilitating the starting of the engine.

As shown in Fig. 8, the magnet 10 has a base 21 attached thereto and this base revolubly rests in the supporting means 22. Thus the field may be adjusted about the armature G.

Figure 11 shows the approximate position of the piston when the ignition during the reverse rotation occurs. The breaker mechanism is located as indicated in Fig. 9.

On ignition E, the crankshaft, will rotate clockwise about of a revolution and ignition occurs at this point. The magneto shaft, M, rotates 1 /2 revolutions during the revolution of the crankshaft E and thus the breaker mechanism will be located as shown in Fig. 2.

The are is equal to 180 degrees less 22 less twice the crank angle as R=2. Adding this to twice the crank angle the following is obtained,

2 times the crank angle plus (1802E2CA) Therefore, the length of the cam track is equal to,

R CA+(180 2ZRCA) Assuming that R=2, CA=6G and 2:20, then the following is attained,

which gives as the length of the cam.

The impulse coupling The impulse coupling is inserted in the drive between the engine shaft and the magneto shaft and does not affect the position between the breaker mechanism 1 and the spark. It operates With reference to Figs. 2, 3, 9, 10 and to stop the rotation of the magneto shaft for a fraction of a revolution and then allows it to accelerate, under the action of a spring, to catch up. This occurs only during the starting revolution.

Referring to Figs. 4-7, inclusive, '70 indicates the pawl carrier which is keyed to the magneto shaft M. A circular groove '71 is formed as shown and a ring 72,slotted as at '73, fits therein. The ring '72 is fastened at 68 to the housing 69, this housing supporting the cam ring T as previously mentioned, and the housing 69 is fastened at 6'? to the magnetic field assembly of the magneto wherebyadjustment thereof, see Fig. 8, also gives adjustment of the ring '72.

The lug 81, on the pawl 80, see Fig. 4, drops into the slot '73 and temporarily prevents reverse rotation of the armature shaft. The pawl 80 is pivoted to its carrier at 79.

A cylindrical shell 78, fixed to the carrier as at 77, has a hole '76 therein for the fastening of a spring 90. The other end of this spring is received in the hole 91 of the driving member and is so wound that when the locking lug 81 locks the spring is caused to wind up.

It is to be understood that the initial rotative movement of the engine occurs with the parts as shown in Fig. 9, this being the starting position, but that the electrical field of the magneto, this being a permanent magnet, see particularly Fig. 8, isshiftedmanually to the position indicated for normal running of the engine.

The spark for running the engine occurs when the piston, see Fig. 1, is approximately at top dead center while the spark for starting must be some'60 or 70 degrees therefrom. The length of the cam track 9 may be computed as follows. Let the'angle of flux or that angle between an axis bisecting the poles and one drawn through the armature when in its position of maximum flux be represented by 2. Let the ratio of speed in R. P. M. between the magneto shaft and the engine shaft be represented by R. and CA the crank angle between the firing points. That is, between the top dead center and the starting position.

Assume that the several parts are located as shown in Fig. 2. If CA is 45 then 90 would be the corresponding movement of the magneto shaft as R=2. But the magneto field must be shifted in order to bring the point 4, or rather a point corresponding to this point 4, around anti-clockwise to the end of the 90 are which is measured or laid off in a clockwise direction from point 2. As the point 4 lies at the starting end of the cam track and as this point should be 2 degrees from the adjacent pole then the angle through which it is moved counter-clockwise to reach the end of the 90 are previously referred to may be found. This arc added to twice the crank angle gives the length of the cam.

The driving member 92 has lugs 93 thereon whereby it is attached to the gear 20 as shown in Fig. 1. Lugs or projections 94 and 95 also extend from the driving member 92 as shown in Fig. 6. It is also formed with a central journal or bearing part which is adapted to slide over the sleeve portion 83 on the carrier.

The carrier also has shoulders 84 and 85, see Figs. and 6, against which the lugs 94 and 95 seat when the magneto is running in its normal direction of rotation. However, when the engine is being started by rocking its flywheel backwards,.the lugs travel towards the positions D,

as indicated by dotted lines in Fig. 6. This reverse movement winds up the spring 90. However, the lugs do not quite reach the positions shown in dotted lines in Fig. 6 as the slanting or cammed surface on the lug of the pawl stands in the path of rotation of one of these lugs and thus the pawl is lifted and thedesired impulse motion obtained. The construction of the windup mechanism is such that every second impulse thereof completes a cycle.

- Referring to Fig. 5, the shaft M continues to the left and supports the breaker arm mechanism 1 as shown in Fig. 1. ,Also, the armature G is mounted upon the same shaft. See Figs. 3, 8 and 10.

In Fig. 5 the memberv 92 is shown spaced from the member 70 but in operation the member 92 is slidably engaged over or around the sleeve portion 83 and consequently, the lugs 94 and 95 are located in the same plane as the shoulders 84 and 85, see Fig. '7, and when the gear 20 is driving the member 92 in the direction as indicated by the arrow BB, see Fig. '7, the lugs 94 and 95 will contact 84 and 85 as shown.

When, during the starting operation, the pistonis moved in a reverse direction, referring to Fig. 11, the large end of the connecting rod travels approximately 90 in a reverse direction and the breaker arm mechanism travels twice that distance. This rearward angular movement varies, as previously mentioned, and is taken care of by properly locating the magnetic field structure upon its base 22. Such is accomplished manually.

At the proper instant the lug 94 or the lug 95 lifts the pawl, seeFig. 7, and thus releases the spring 90 whereby a quick movement of the armature through its field of magnetic flux is had in order that a hot spark may be obtained. After a slight speed of the engine is attained the pawl 80 is held outwardly by centrifugal force.

While I have described a complete embodiment of my invention I do not wish to be limited to the particular construction shown, my invention being in fact limited solely by the attached claims.

I claim- 1. In an internal combustion engine of the class described, the combination of a magneto adapted to furnish electrical energy for the ignition system thereof, an impulse coupler connected to the magneto to drive the same, means to drive the impulse coupler in synchronism with the engine, said impulse coupler comprising a spring adapted to be wound up during reverse movement of the means which drives the coupler, and releasing means adapted to release the spring after a predetermined movement in said reverse direction for the purpose described.

2. A combination of elements as set forth in claim 1 in which the means to drive the impulse coupler in synchronism with the engine consists of mechanism motivated by a moving part of the engine.

3. A combination of elements as recited in claim 1 in which the frame of the magneto is rotatably mounted whereby it may be adjusted around the axis of the same thus regulating the timing of the spark so that said spark occurs at the desired point.

4. In combination, an internal combustion engine adapted to run in one direction but which is started by rocking in the opposite direction, said engine having the usual crankshaft and spark plug, a magneto, mechanism between the magneto and the crankshaft to drive the magneto at twice the speed of the engine crankshaft, said mechanism including an impulse coupler having a spring which is inoperative, as regards relative movement of one part of the spring with respect to another part of the spring, on normal running of the engine but which is wound up during the reverse starting motion of the engine, means to trip the spring during said reverse starting motion of the engine, said magneto having a secondary winding, connected to said spark plug, and a primary winding, an interrupter cam follower mounted upon the magneto shaft and a special cam adapted to receive the follower, said cam having a raised portion, one end of said raised portion breaking the primary circuit during running operation of the engine and the other end breaking the primary circuit during the starting operation of the engine.

5. .A two stroke cycle gas engine having a magneto, means for driving said magneto at twice the speed of the engine crankshaft, said means including an impulse coupler which is inoperative during normal rotation of the engine but which functions during reverse rotation, a circuit breaker mechanism on the magneto shaft and a special cam adapted to operate the circuit breaker mechanism, said cam having a raised portion about in length, one end of the cam operating the breaker mechanism to initiate the running spark and the other end of the cam similarly causing the starting spark.

6. In an internal combustion engine adapted to normally run in one direction but which may be rocked backwards during the starting operation, the combination of, a magneto including an armature, electrical field means located thereanism including cam means attached to and movable with the electrical field means, one end of the cam means being operative to break the circuit when the engine is running normally and the other end of the cam means being operative to break the circuit during the starting operation, means to drive the armature, the angular dimension of the distance between the ends of the cam means being approximately equal to the ratio of the speed between the magneto shaft and the crankshaft multiplied by the angle on the crankshaft between the point of normal ignition and the position attained by the crank upon maximum backward rotation of the same plus less twice the distance in degrees between the geometrical dead center of the armature in alinement with its poles and the position at which the best running spark occurs and also less the product of said above ratio multiplied by the above crankshaft angle.

7. In an engine of the class described having a magneto for producing a running spark and a starting spark when rotated in opposite directions, the length of the cam on the magneto being equal to R CA+(180-22RCA) in which R is the ratio between the speed of the magneto shaft to that of the engine, CA is the angle between the point of normal firing of the engine and the point of starting firing and Z is the angle between the axis biseoting the poles and one drawn through the armature when it is in its desired firing position.

BERTUS L. MoLANE.

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