US1486229A - Chusetts - Google Patents

Description

March 11 1924. 1,486,229

. H. H. CLARK IITERRUPTER MECHANI SM Filed June 25 1920 ATTORNEYS.

Patented Mar. 11, 1924.

UNITED STATES 1,486,229 PATENT OFFICE.

HAROLD H. CLARK, OF SPRINGFIELD, MASSACHUSETTS, ASSIGNQR '10 WICO ELECTRIC COMPANY, OF SPRINGFIELD, MASSACHUSETTS, .A CORPORATION OF MASSA- CHUSETTS.

INTERRUPTER MECHANISM.

Application flledlune 25, 1920. Serial No. 391,608.

Springfield, in the county of Hampden and State of Massachusetts, have invented new and useful Improvements in Interrupter Mechanism, of which the following is a specification.

This invention relates to improvements in interrupter mechanism which, although capable of other applications, is particularly adapted for use with ma etos. The invention is especially suitable for the diflicult work of sharpl closin holding closed, and subsequently s arply reaking of an electrical circuit all within an exceedingly short interval.

An example of a magneto of a character which particularly necessitates the use oi interrupter mechanism of the character alluded to, is the fiywheel type of magneto. In the flywheel magneto, the relative movement between the armature and the cores is obtained by mounting one, preferably the armature, on the flywheel. The armature periodi ally, as for example once on each revolution of the flywheel, moves into close proximity to the cores to establish a magnetic circuit therethrough and very shortly afterwards leaves the cores to interrupt the magnetic circuit thus established. The angular movement of the armature from the position in which it makes to that in which it breaks the magnetic circuit is very small and'may, for example, be no more than onefiftieth part of one revolutionofthe flywheel. Thus, with an internal combustion engine operating at 1200 revolutions per .minute, the time of the small angular movement mentioned may be no more than one thousandth part of a second.

During this same very small interval, it is desired to quickly close the breaker points (which short circuit the primary windin of the cores of the magneto), hold them closed for an interval, and then sharply open them. The usual interrupter mechanism embodying fixed and movable breaker points with the latter actuated by a single cam, is not suitable for accomplishing the results desired, because given a cam that will produce a practically instantaneous closing, such cam cannot obviously produce a practically instantaneous opening. That is, an abrupt radial drop of the cam follower on the 'cam cannot be shortly afterwards accompanied by an abrupt radial rise. One or the other movement of the cam follower must needs be accomplished less rapidly and less sharply than the other. This invention is concerned with interrupter mechanism which is ada ted among other things, to the solution of the above problem.

An object of the invention is to provide improved interrupter mechanism, involvin breaker points, which may be sharply close and, after a .very short interval, sharply separated.

Another object of the invention is to provide, in interrupter mechanism, cooperatin and relatively movable breaker. points wit actuating mechanism therefor, which is designed to permit the breaker points to be sharply brought into engagement at all times irrespective of wear on the points.

Another object of the invention is to provide, in interrupter mechanism of the ty wherein cooperating breaker ints are he (1 in contact under spring. tension, means for releasing such tension at about the time of opening the breaker points, whereby the resistance to movement of the movable breaker point is greatly reduced to permit quick acceleration thereof.

Another object of the invention is to provide means for se varating the breaker points with a hammer low action to produce an exceedingly rapid separation thereof.

Another obgect of the invention is to utilize the tension of the spring, when released at'or about the time of separation of the breaker points, as a means for actuating the hammer blow separating means.

Another object of the invention is to provide means for retensioning the spring, after its release without closing the breaker points.

Other objects and advantages will appear in the following description and in the illustrative embodiment of the invention in the 190 accompanying drawings, in which:

Fig. 1 is an elevational view showing an engine provided with a magneto of a type with'which the interrupter mechanism may advantageously be used;

Fig. 2 is an enlarged front elevational view of the interrupter mechanism, the cover of its enclosing casing being removed;

Fig. 3 is an enlarged side elvational view of the actuating cams;

Fig. i is an enlarged bottom plan view of the cam followers;

Fig. 5 is a cross sectional view taken on the line 5-5 of Fig. 3 and drawn to a somewhat smaller scale;

Fig. 6 is a diagrammatical view of the essential parts of the magneto showing their relation with the interrupter mechanism; and

Fig. 7 is a fragmentary elevational view of a. modification in the mounting of the breaker points.

Referring to these drawings: A represents a well-known type of internal combustion engine, which, since'the invention is independent of, and not concerned with, the structural details thereof, has been illustrated in conventional form only. For the present purposes, it will sufilce to state that c is its flywheel and d the cam shaft. T he latter drives the interrupter mechanism which is housed in a casing 6 having a cover g.

The magneto chosen to illustrate this invention, embodies a source of magnetic flux, as a permanent magnet k; a suitable primary generating winding, as the coils i; a secondary generating winding, as the coils j; cores is connected to opposite poles of the source it and extending through the coils i; and an armature Z to periodically bridge the free ends of cores 7:. All these elements, except the armature Z, are stationarily mounted in proximity to the flywheel c as indicated in Fig. l. The armature Z, however, is attached to the tiywheel c and arranged to move once each revolution into close proximity to the ends of cores Fa to establish a magnetic circuit therethrough. The full lines in Fig. 6 show the armature in such position and the dotted lines show theposition of the armature at or about the time that the magnetic circuit, thus established, is broken. It will be apparent that the time taken by the armature in moving from the full line to the dotted line position is exceedingly small;usuaily merely an exceedingly small fraction a second.

The secondary coils j are electrically connected in series and one is electrically connected to the spark plug on as conventionally indicated in l primary coils 2' are likewise connected in series and one of their termin as it, is grounded. The other terminal connected by wire to one of the breaker oint, as 3.0, later to be described and the other bread"- er point, as 11, is grounded. condenser 39 is bridged across the breaker points in the usual manner.

The breaker points it) and 11 are normally maintained in separated relatio leaving the primary winding open circuit- 7. This is desirable in order to permit the flux to idly build up in cores It, which action would be impeded if the primary winding were short circuited. Having the flux established to a maximum in cores it, it is then. feasible to close the breaker points 10, and 11, and this is done, as near as may be, at the time above defined. The armature Z, at such time, is approximately in the full line position shown in Fig. 6. The points 10 and 11 are then held closed until at or about the time of breaking of the magnetic circuit. At such time the armature Z is approximately in the dotted line position. In defining the times for closing and opening, I have done so by giving as nearly as possible the relative positions of the armature and cores. These positions may, of course, be varied within limits but I have given those which I deem preferable.

In addition to the elements of the magneto, as described, there is preferably pro vided a second path for the flux from the magnetic source h. This path is one of constant and relatively high reluctance and may be made up of a series of laminations g, which are stacked face to face between the cores 70, as diagrammatically indicated in Fig. 6. These laminations q afford a path of greater reluctance than that through the cores Z; and armature Z when the latter is in position to magnetically connect the core ends. Such path, however, is of considerably less reluctance than that through the cores when the armature is otherwise positioned. Consequently, a large part of the flux then flows through the laminations g, which. then function something like a keeper for the magnets h and prevent undue loss of magnetism.

lhe presentinvention, being concerned more particularly with the interrupter mechanism, is largely independent of the details of the magneto and the mechanism may well be used under many other conditions than those described. Particular pains, however, have'been taken to disclose in some detail the magneto structure realizing that it presents an illustrative example of most severe conditions to be met by the interrupter mechanism,

Referring now to Figs. 2 to inclusive, the fixed breaker point is mounted, preferably arljustably as indicated, in a bracket 12, which is suitably secured to and insulated from the back of the shell like interrupter casing e. The movable breaker point 11 is carried on the end of an arm 13, which is pivotally mounted on a stud 1a projecting from the back of casing e, and the. latter, be- 1':- frame, constitutes the ground conventionally indicated in Fig. 6. The arm 13 may advantageously be struck up from sheet metal and provided with depending side webs 15, through and between which a bushlti extends, the latter being free to turn metallic and connected to the engine on stud Beneath the arm 13, which is relatively wide, are two cams 1'7 and which are mounted on the described shaf d as will appear,.and a part of arm 13', overlying the cam 17, is bent downwarly to form a follower 19 for such cann A second arm 20, formed similarly to arm 13 with side webs 21, is pivotally mounted on the bushing 16 and is free to turn independently of arm 13.. The free end of arm. 20 bears a follower 22 for engagement with cam 18, the offset relation. of followers 1. an beingclearly shown in Fig 1. The arms 13 and 20, which are normally substantially at right angles, are connected, as by a coil spring 23, so as to be yieldin ly drawn toward one another, and. so as to hold the followers 19 and. 22 on their respective cams. Fixed to arm 20, as by being formed inte grally with one web 21, is a hammer arm at which underlies and is normally spaced from the arm 13.

The cams 1'7 and 18 are suitably fixed together, as for example, by the screws 25.

('Fig. 2) which may, as shown, pass through slots 26 in cam 17, whereby the relative angu lar positions of the cams may be adjusted if desired. The came 17 and 18 are preferably loosely mounted on. a hub 27 (Fig. 3) which is suitably fixed to the shaft 0?. Such hub has a flange 28 against which the end face of cam 18 abuts, and a split ring '29 sprung'into a groove in hub 27 cooperates with flange 28 to hold the cams against axial displacement. Cam 18, in its end face, is recessed to afford a shoulder 30 and an inclined surface 31leading from the base of this shoulder to the said end face, thereby affording the equivalent of a single ratchet tooth. Slidable in flange 28 is a pawl 32, the inner encLof which is normally engaged with shoulder 30 to drive the latter in the direction of the arrow shown in Fig. 3. On movement of shaft of in the reverse direction, as on backfiring, the pawl 32 is raised out of engagement with shoulder 30 by the-surface 31 and the cams are therefore not then driven. A spring 33 tends to hold pawl 32 in its inner and shoulder-engaging position.

Each of the earns 17 and 18 are formed as true cylindrical surfaces concentric with shaft of. Each, however, has a cut in its periphery to afford a radial surface or let off portion and a relatively gradual rise from such portion to the circular surface of the cam. The radial surfaces of cams 17 and '18 are indicated at 34 and 35 respectively and the gradual rise at 36 and 37 respectively.

The shoulders 34 and 35 are sospaced that, when the cams rotate in the lanned direction, the follower 19 will be all by shoulder 35 before the follower 22 reaches the shoulder 34. This condition is shown in Fig. 2 and the drop of follower 19, while fol-- lower 22 is still held to the circular portion owed to drop of its cam 17 allows the breaker points 10 and 11 to he sharply and aunost instantaneously closed by the contraction. of spring 23. The breaker points are irtaiued closed for a short interval while follower 22 is moving from the illustrated position to the shoulder 34, it being noted that, during this slight movement of the cams, the surface 37 will not have lifted the follower 19, As soon as shoulder'34 permits follower 22 to drop, the spring 23 contracts and its tension. is expended in quickly moving the arm 20 and its connected hammer arm 24. The parts 20 and 24;, being light and at such time encountering practically no resistance to movement, accelerate rapidly and, by the time sistance (since the tension. of spring 23 has been entirely released) and thus is rapidly and almost instantaneously moved. The follower 19 is released by shoulder 35 at or about the time that armature Z comes into the position shown in full lines in Fig. (i, and the follower 22 is released by shoulder 34: at or about the time that armature Z reaches the osition shown in. dotted lines in. Fig. 6. T e points 10 and 11, having been thus separated do not again immediately close. During the outward flight of arm 13, under the force of hammer 24, the cams l7 and 18 continue to turn and, by the time that gravity returns arm 13, the cam 18 has moved sufficiently so that the follower 19 drops onto the surface 37 at a point such as to prevent re-engagement with the breaker points. In connection with the outward flight of arm 13, it is to be noted that the arm is not suddenly arrested by abutment with fixed parts in a manner such as to produce noise and cause rapid wear. The arm, in its outward movement, is arrested by the spring 23 and thus yieldingly without sharp impact. on continued movement of the cams, the followers 19 and 22 are raised, the former slightly in advance of the latter and thev raising of the followers separate arms 13 and 20 causing spring 23 to be re tensioned with out closing the breaker points 10 and 11.

It has been found that the movable breaker point will, under some conditions, rebound after its engagement with the fixed breaker point and produce a separation of the points at an undesired time. The premature separation of the breaker points can be prevented by reducing the gap between them when in separated relation. Another way of preventing this undesired action, and one which is advantageous since it permits a relatively large gap between the points, is illustrated in Fig. 7. As there shown, the relatively fixed point 10 is mounted on the end of a thin arm 40, preferably of spring metal, which arm is secured at its other end to a bracket 12' mounted in the interrupter casing e similarly to the bracket 12, heretofore described. Between the free end of arm and the adjacent portion of bracket 12 is placed a pad 41 of suitable material, such as felt for example. The point 11 when moved against point 10 moves arm 40 against pad 41 whieh yields to absorb the shock due to the engagement of the points. The pad 40 functions as a cushioning or damping means and prevents the rebounding of the point 11 and thus a premature separation of the points. The pad 41 also lessens the shock of engagement of the points, but also lessens the wear on the latter.

It will thus be seen that the invention provides an interrupter mechanism, which while capable of use under the conditions ordinarily encountered, is characterized in that it is also capable of meeting the special conditions and exacting requirements of flywheel magnetos of the general character disclosed. It permits rapid and, for all practical purposes, instantaneous closing of the breaker points followed, after an exceedingly short interval, by an equally sharp and rapid opening of the breaker points. Not only are the breaker points sharply closed but they are closed and opened at given angular positions of the armature independently of wear. such as wear of the points themselves or of the cam follower or cam and this is of vital importance where, as here, so little variation is tolerable in the angular position of the armature both at the instant of opening and at the instant of closing the points.

In connection with wear of parts, it should be noted that the mechanism is so designed as to reduce wear, by eliminating as far as possible blows under the pressure which are productive of wear. Of especial importance, due to the very small time intervals available for action, is the elimination, so far as possible, of resistance to motion of the cam followers and connected parts. Such parts are, to begin with, made light and therefore have little inertia. The arm 20 and hammer arm 24, at the start of their movement when released by shoulder 34, meet with no appreciable resistance and thus accelerate quickly and rapidly acquire velocity for the delivery of the hammer blow upon the arm 13. At the time of such blow the tension of spring 23 is relaxed so that arm 13encounters no appreciable resistance and accordingly is moved almost instantaneously to separate the breaker points.

The invention has been disclosed herein, in an embodiment at present preferred, for illustrative purposes, but the scope of the invention is defined by the appended claims rather than by the foregoing description.

What I claim is 1. Interrupter mechanism, comprising, co-

operating and relatively movable breaker points, rotary timing mechanism for controlling the opening and closing of said points, means operable from said mechanism at predetermined times to move said points into engagement at a speed independent of its rotative speed, and means subsequently operable from said mechanism to move said points into separated relation and at a speed independent of its rotative speed.

2. interrupter mechanism, comprising, fixed and movable breaker points, a cam for holding the latter away from the former and for periodically suddenly releasing the latter for free movement into engagement with the former, a hammer member adapted to suddenly separate the breaker points, and a second cam for normally holding said member in inactive position and for periodically suddenly releasing said member to cause the separation of the breaker points.

3. Interrupter mechanism, comprising, a fixed breaker point, a movable member carrying a cooperating breaker point, a cam for holding said member so positioned that the breaker points are separated and for periodically suddenly releasing it to permit engagement of said points, a hammer member for engagement with the first named member to cause separation of said points, a second cam for holding the hammer member disengaged from the other member and periodically suddenly releasing it, and means for moving both said members.

4. Interrupter mechanism, comprising, a fixed breaker point, a movable member carryin a cooperating breaker oint, a cam for holding said member so positioned that the breaker points are separated and for periodically suddenly releasing it to permit engagement of said points, a hammer member for engagement with the first named member to cause separation of said points, a second cam for holding the hammer member disengaged from the other member and, periodically suddenly releasing it, and yieldable means tending to hold said members in engagement with their cams and for actuating either member when released by its cam.

5. Interrupter mechanism, comprising, c0- operating and relatively movable breaker points, rotary timing mechanism for controlling the opening and closing of said points, means operable from said mechanism at predetermined times to move said oints into engagement at a speed inde en ent of its rotative speed, and means su sequently operable from said mechanism at a definite time after the operation of the first named means to move said points into separated relation and at a speed independent of its r0- tative speed.

6. Interrupter mechanism, comprising, a fixed breaker point, a movable member carrying a cooperating breaker point, a cam IOU having a dwell portion for normally holding said member in such position that said points are separated and a let off portion for suddenly releasing said member and permitting said points to be engaged, a movable hammer member adapted to engage and move the first member, a cam having a dwell portion for normally holding the hammer member out of engagement with the other member and resilient means urging said members toward their respective cams, said second cam having a let off portion to suddenly release the hammer member at a predetermined time interval after the release of the first member and move the latter to disen age said points.

nterrupter mechanism, com rising, cooperating relatively fixed an movable breaker points, a cam follower connected with the movable breaker point, a cam for said follower connected with the movable fixed breaker point, a pivoted arm carrying.

a cooperating bre'aker point, an actuating cam for said arm, said cam having a dwell portion for holding the .arm so positioned that the points are separated, a'let ofi portion for suddenly releasing the arm for free movement, and a gradual rise from the latter to the former portion; a second pivoted arm having a part adapted when the arm is released to engage and suddenly move the first arm, an actuating cam for the second arm, said cam having a dwell portion to hold the second away from the first arm,

a let off portion to suddenly release the second arm for free movement toward the first arm, and a gradual rise from the latter to the former portion; and a yieldable means connecting said arms and tending to hold each in engagement with its cam.

9. Interrupter mechanism, comprising, a fixed breaker point, a pivoted arm carrying a cooperating breaker point, an actuating cam for said arm, said cam having a dwell portion for holding thearm so positioned that the points are separated, a let off portion for suddenly releasing the arm for free movement, and a gradual rise from the latter to'the former portion; a second pivoted arm having a part adapted when the arm is released to engage and suddenly move the first arm, an actuating cam for the second arm, and said cam having a dwell portion to hold the second away from the first arm,

a let off portion to suddenly release the second arm for free movement toward the first arm, and a gradual rise from the latter to the former portion; and a yieldable means connecting said arms and tending to hold each in engagement with its cam, the second cam arranged to release its arm shortly after the release of the first arm by its cam and before the first arm is moved by the rise portionpf its cam.

10. Interrupter mechanism, comprising a fixed breaker point, a pivoted arm carrying a cooperating breakerpoi'nt, an actuating cam for said arm said cam having a dwell portion for holding the arm so positioned that the points are separated, a let off portion for suddenly releasing the arm for free movement, and a gradual rise from the latter to the former portion; a second pivoted arm having a part adapted when the arm is released to engage and suddenly move the first arm, an actuating cam for the second arm, said cam having a dwell portion to hold the second away from the first arm, a let off portion to suddenly release the second arm for free movement toward the first arm, and a gradual rise from the latter to the former portion; ,and a yieldable means connecting said arms and tending to hold each in engagement with its cam, the second cam arranged to release its arm shortly after the release of the first arm by its cam and before the first arm is moved by the rise portion of its cam, said yieldable means producing no turning movement of the members around their axis in either direction after the breaker points separate, and said rise portions arranged to move the arms to place the yieldable means under increased stress without closing said breaker points. 7

l1. Interrupter mechanism, comprising, cooperating and relatively movable breaker points, rotary timing mechanism for controlling the opening and closing of said points, means operable from said mechanism at predetermined times to move said points into engagement at a speed independent of its rotative speed, means subsequently operable from said mechanism to move said points into separated relation and at a speed independent of its rotative speed, and damping means associated with one of said points to prevent rebounding of the movable point and premature separation of the points following the engagement of the latter.

l2. Interrupter mechanism, comprising, cooperating breaker points, a cam having a dwell portion for holding the points in separated relation and a sharp let oil portion for suddenly releasing the points to permit engagement thereof, a hammer :Eor suddenly separating the points, a cam controlling the hammer and having a dwell portion to hold it in inactive position and a sharp let off portion to suddenly release it for action, and

resilient means for actuating the hammer and said points when released.

13. Interrupter mechanism, comprising, cooperating breaker points, a cam having a dwell portion for holding the points in separated relation, and a sharp let off portion for suddenly releasing the points to permit engagement thereof, a hammer for suddenly separating the points, a cam controlling the hammer and having a dwell portion to hold it in inactive position and a sharp let off portion to suddenly release it for action, and resilient means for actuating the hammer and said points when released; the second cam releasing the hammer at a definite predetermined time after the release of said points.

In testimony whereof I have afiiXed my signature.

HAROLD H. CLARK.

Images