US2163336A - Spark timer for hammers - Google Patents

Description

June 20, 1939. c, CHARLES 2,163,336

SPARK TIMER FOR HAMMERS Filed April 5, 1937 2 Sheets-Sheet 1 June 20, 1939- c. L. CHARLES SPARK TIMER FOR HAMMERS Filed April 5, 1937 2 Sheets-Sheet 2 m 0 I 0 w f v z 67? I I CarZj U/mrZea; @W%

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Patented June 20, 1939 SPARK TIMER FOR HAMMEBS 'Carl L. Charles, Winnetka, 11]., assigncr to Gas Tool Patents Corporation, a corporation of Delaware Application April 5, 1987, Serial No. 135,185 14 Claims. (Cl. 123-1465) This invention relates to internal combustion percussive hammers, and more particularly to spark timers therefor.

One feature of this invention is that it provides means for varying the time of commencement of ignition; another feature is that it provides means for varying the duration of flow of ignition current; another feature of this invention is that it provides improved mounting means for the ignition points; yet another feature. of this invention is that a mounting is provided sealing the points from a contact with inflammable vapors; still another feature of this invention is that means is provided for varying the durationof flow of ignition current in accordance with the temperature of the hammer, which means may be either manual or automatic; other features and advantages of this invention will be apparent from the following specification and the drawings, in which:

Figure 1 isa vertical elevation, partly in sec tion, of an internal combustion percussive tool embodying this invention; Fig. 2 is a fragmentary sectional view of the hammer shown in Fig. 1; Fig. 3 is an elevation of the timer housing and mounting; Fig. 4 is a view, partly in section, along the line 44 of Fig. 3; Fig. 5 is a detailed sectional view of a modified form of timer; Fig. 6 is a detailed sectional view of a timer particularly designed for varying the duration of flow of ignition current; and Fig. 7 is a sectional view of a timer having means for automatically varying' the timing.

The internal combustion hammer or percussive tool illustrated herewith has a cylinder ill having a piston hammer ll freely reciprocal therein and adapted to impart blows to a tool at the bottom of the hammer through the anvil II. A piston return spring assembly l3 urges the piston upwardly. The hammer is provided with a charge forming device I provided with a tank adapted to contain a liquid fuel, a carburetor, and the necessary manifold passages to enable a combustible charge to be drawn into the chamber l5 beneath the piston and thereafter transferred to the combustion chamber l6 above the piston through the passage II, in accordance with known two-cycle engine practice.

The hammer is provided with an ignition system including a spark plug l8 and a timer l9. An ignition unit including a battery or other source of current and a buzzer operated spark coil is connected, in accordance with known practice, to the hammer through a cable having a high tension and a low tension circuit therein. The

high tension circuit is connected to the spark plug by the wire 20, while the low tension circuit is connected to the timer by the wire 2|, thus enabling the timer to control ignition by control of the current flow therein. It will be noted that the piston II is provided with a cam surface 22 adapted to actuate, upon reciprocation of the piston, a cam follower or plunger in the timer I9.

The hammer shown herein as one embodiment of this invention is of the same fundamental type as that shown in Mould Patents Nos. 1,868,754 and 1,997,072, for example, and the general mode of operation of the hammer is fully described therein.

In order to secure efilcient operation of an ll internal combustion engine it is, of course, necessary to have the high tension spark or ignition means initiated at a particular time with respect to the reciprocation of the piston in the cylinder. Too early ignition results in knocking, over heating, and other troubles; and too late ignition re-. sults in poor combustion efliciency, loss of power, slower action of the hammer, and the like. The point at which the spark should be initiated also varies somewhat in accordance with the temperature of the hammer, and it is preferable to provide means for adjusting the action of the timer in this respect to vary the timing of the ignition.

Where ignition of the make" type is used, as disclosed on this particular embodiment of the invention, high tension sparks continue to flow across the spark plug electrodes as long as the points in the timer are closed. This is, of course, a drain on the battery and therefore it is preferable not to have ignition current flow any longer than necessary. In order to start a hammer of this type, however, it is necessary to have a much'longer time of ignition current flow than thatwhich will effectively operate the hammer after it is warmed up. It is thus also desirable to provide means, as here disclosed, for shortening the duration of flow of ignition current as the hammer warms up. It will be seen that proper control of the timing of the hammer thus includes one or both of the two elements discussed above: the first, the point or time of initiation of ignition; and second, the duration of ignition current flow.

In the particular timer illustrated in Figs. 2 to 4, the cylinder III is provided with an opening 23 therethrough transverse to the axis of the cylinder. A sleeve member 24 is held therein by studs 25 tapped into the cylinder wall or a boss provided therefor. Within the sleeve 24 is a lonthe cam surface 22 on the piston. A coil spring gitudinally movable plunger 28 having a roller 21 on the inner end thereof adapted to contact 28, axially disposed with relation to the plunger,

' biases 0r urges it against the piston, sothat reciprocation or movement of the piston in the cylinder effects longitudinal movement of the plunger 28.

The plunger 28 has movably mounted therein and coaxial therewith a second longitudinally movable plunger 28. The inner end of the plunger 29 is provided with a stop Ill adapted to contact a shoulder on the plunger 28 to prevent outward movement of the second plunger with respectto the first. A coil spring ll surrounds the second plunger and lies between a shoulder there-- on and a shoulder on the plunger 26, yieldingly urging the second plunger outwardly with respect to the first plunger. It will be thus seen that the two plungers may telescope within each other to the extent of the space provided between the stop 30 and the roller 21, so that the plunger 26 may continue to moveoutwardly as a result of movement of the piston even though the second plunger 29 has ceased outward movement.

A pair of cooperating ignition points 32 and 23 are provided. The point 33 is adiustably mounted on the end of the plunger 29 and adapted to be moved toward and into contact with the point 32 upon movement of the first plunger 26. This point 22 is mounted on a member 24 passing through insulated washers l5 and 36 on each side of an opening 31 in the housing 38. The outer end of the member 34 is threaded, and a nut 39 is provided for locking the member in place. x

The points 32 and 23 are operatlvely connected in the low tension ignition circuit to control ignition as a result of a change of relationship, that is, from open to closed relationship, or vice versa. The point 32 is insulated from the hammer body and connected to the wire 2| through the connecting lug 4l. The point 28 is grounded to the hammer through the plungers in contact with the cylinder wall. It will be noted that the timing of the hammer may be varied by moving the point 33 toward or away from its cooperating point to vary the instant of initiation of ignition with respect to movement of the piston. The lug 40 engages a flattened portion of the member 34 and acts as a wrench for holding the member while the nut 39 is drawn up tight. It is prevented fromfalling out of place when the nut is slightly loosened by the shoulder portions engaging the washer.

The springs providing the necessary bias on the two plungers are here shown as nested coil springs in substantially coaxial relationship. The

spring II is of lighter construction than 2|, so

that during the latter part of the movement, when the plunger 26 is pushing against both springs, there will not be undue wear on the cam sin-face. The particular arrangement shown has been found to be very rugged as well as efilcient. The plungers and springs are so arranged that the terrlfic vibration of the hammer when in operation causes little or no wear and difiilculty with the parts. The springs particularly have been found to stand up much better than fiat springs of various types originally used in the hammers. 4

Shims may be inserted between the outer or plate portion of the member 24 and the wall of the cylinder, so that when the studs 26 drawn up the final position of the cam follower with respect to the piston and cam surface thereon will be affected thereby. The presence of theseshims serves two purposes. They might be inserted or removed to change the initiation point, to compensate for wear of the cam surface or cam follower, or both. Adjustment here also assures the minimum over travel of the point it necessary to avoid intermittent separation of the pointfrom vibration and spring surge during the period it is desired to have them stay 7 closed. That is, if the points Just barely touch and then stay in that position for an appreciable time interval, surges in the springs 20 and SI, vibrations in the body of the hammer, or both, may cause the points; to separate momentarily and thus interrupt ignition. Where there is considerable over travel of the first plunger 2 the spring'll is put under suillcient tension to insure that the points 22 and. 32 remain in contact during the interval that contact is desired. In the particular embodiment of this invention illustrated in Fig. 2, for example, there is about forty-seven thousandths of an inch diiference between the low point and the high. point on the cam surface of the piston, so that the plunger 26 moves about this distance during reciprocation of the piston. The points are preferably set with an initial gap of only about five thousandths of an inch, so that there is thus about forty-two thousandths of an inch over travel to insure maintenance of the points closed.

In order to facilitate original adjustment of the shims in the shop or in the field, the outer face ll of the plunger 2 is arranged to be about forty-five thousandths of an inch from the outer face 82 of the fiat portion of the member 24 when the member 26 abuts the shoulder 28. In order to insure proper initial position of the plunger and points with respect :to the piston it is then only necessary to bring the highpoint of the cam surface on the piston adjacent the roller 21, so that the plunger 26 is moved as far to the left as it would be in operation, and then to insert or move shims beneath the flat portion of the member 24 until the outer surface ll of the plunger 26 is flush with the surface 82. Thismakes a very convenient assembly or field adjustment, and one which is independent of wear on the cam surface or roller.

The housing it is so constructed and arranged as to seal the points from atmosphere. This is a desirable feature, since it prevents-any chance of a sparking at the points igniting combustible vapors which may be present in the air about the hammer. The tank in the charge forming device l4 contains a supply of relatively volatile inflammable fiuid, usually gasoline, which fluid is open to atmosphere through the tank filler cap, the air intake to the carburetor, and the like. Portions of unburned charge are frequently exhausted from the cylinder, moreover, through the exhaust port 4|. Priming of the hammer when it is cold in order to facilitate starting also increases the gasoline vapors present in the atmosphere immediately about the hammer. when these hammers are used near gas mains, in mines, or the like, combustible vapors, or gases may be present which are of an even more .explosive nature. Enclosing the points in a housing which seals them from atmosphere, therefore, is a safety feature tending to prevent undesired ignition of these .vapors. a

In the modification of this invention illustrated are inFig. 5. the longitudinally movable plunger 42 1g has mounted in the end thereof a point adapted to cooperate with a point 44 mounted in a second longitudinally movable plunger 45 slidably iournalled in the housing 46.. Coil springs 41 and 48, which may be duplicates, are provided urging both plungers in the direction toward the cylinder. A reinforcing beam 46 extends across between studs. similar to 2.5.

In the particular modification being described the entire housing 46 is insulated from the cylinder of the hammer by the appropriate insulating washers 50 and 5!, so that the connecting lug 52 is not insulated fromthe housing. When reciprocation of the piston moves the plunger 42 to the left, the point 43 makes contact with the point 44 and continued outward motion of the plunger 42 is absorbed by movement of the second plunger 45. I

In this particular modification a sleeve 53\is shown as threaded into the opening in the wall of the cylinder Iii. The base plate or sleeve mem-. ber 54 is bolted to the cylinder in the same manner as was previously described in connection with Fig. 3. The outer end of the threaded sleeve 53 provides a stop or shoulder against which the plate 54 is bolted. Rotation of the threaded sleeve 53 prior to drawing down the studs holding plate .54 on the cylinder thus adjusts the point of initiation of ignition with respect to reciprocation of the piston.- It is to be understood that the spacing between the points may be adjusted, if desired, by insertion or removal of shims between the housing 46 and the base plate 54.

Another modification is illustrated in Fig. 6. wherein the timer is particularly designed to enable variation of the duration of ignition current in accordance with temperature changes in the hammer. A longitudinally movable plunger 55 is adapted to be moved through contact with the cam surface on the piston, as previously described. and has mounted on the outer end thereof the point 56 adapted to cooperate with the second point 51 of the pair of points. This latter point is mounted on a movable member 58 slidablymounted in a bearing 59. A coil spring 60 biases the movable member and point 51 toward the cylinder, but an adjustable stop 6| prevents movement beyond a certain desired pos tion. so that the points 56 and 51 are separated during the major portion of the movement of the piston. The movable member 58 also has mounted thereon a point 62 adapted to cooperate with a point 63 mounted on a movable means here shown it to remain in contact therewith during initial movement to the left of the member 56. A stop against which the spring 64 abuts is here shown I as a stud 65 threaded into an insulating bushing in the housing 66 and manually adjustable through rotation of the outer knob or head.

In this particular embodiment, as the piston rises in the cylinder and compresses the charge above it, the plunger 55 moves outwardly as a result of its contact with the gently sloping cam. surface on the piston until, at the desired instant, the point 56 contacts the point 51 and completes the low tension circuit to energize the spark coil and ignite the charge. As the piston continues to rise the plunger 55 carries the member 58 outwardly with it, the points 62 and 63 still maintaining a close relationship. After a predetermined amount of movement of the member 58, however, the spring 64 contacts the end of the stop screws 66 and further outward movement of the plunger and member causes the points 62 and 63 to change their relationship .and separate. This breaks the ignition circuit, even though points 56 and 51 are still closed.

The modification shown and described in the preceding paragraphs gives full control of the timing, and is economic of battery power. Ad- Justment of the stop screw 6i varies the point at which ignition is initiated with respect to the stroke or reciprocation of the piston; and rotatiorr'of the stop screw 65 varies the length of time during which ignition current fiows. This latter adjustment is so .arranged as to be easily operable at any time. in order that the length of current flow may be reduced as the temperature of the hammer rises. When the hammer is being started cold the screw 66 is backed oil so that there isa relatively long sparking period to take advantage of delayed ignition. As the hammer warms up the stop screw may be turned further inward to vary the period during which the circuit is closed so that the ignition current, generally supplied by a light dry battery, shall not be.

any greater drain on the battery than necessary.

A modification designed to provide automatic control of the period during which ignition current fio'ws is illustrated in-Fig. 7. As described in connection with Fig; 6, a longitudinally movable plunger 61 and a movable member 68 carry points 69 and 16, respectively, which points are adapted to be closed at a desired instant to complete-the ignition circuit and initiate sparking across the electrodes of the plug. The outer end of the member 66 alsocarries a point ll adapted to cooperate with a point I! normally in contact therewith.

The point 12, however, is here shown as mounted on a movable support 13 which comprises a pair of metals having different coeflicients of expansion. The member 13 thus assumes different free positions in accordance with the temperature of the hammer. The bimetallic movable element is so arranged that when the hammer is cold the point I2 follows the point ll outwardly and remains in contact therewith throughout a relatively long interval. As the hammer warms up the free or unbiased position of the movable mounting means 13 moves further towards the cylinder, so that the points 'II and 12 remain in contact for a shorter interval of piston movement. The period of ignition current flow is thus automatically regulated to effect easy starting and battery economy when the hammer is warmed up and working.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the apigniting said charge, said system including a pair of cooperating ignition points for controlling said ignition; a longitudinally movable plunger actuated by reciprocation of said piston through con- 4 creases" tact with a cam suriace thereon and elective to move one of said points toward the other; a coil spring opposing said movement; a second longi-- tudinally movable plunger so constructed and arranged asto permit iurthermovement of said first plunger after said points have come into contact; and s.- secondcoil spring opposing the movepiston for breaking said circuit; and means for adjusting the period during which said circuit is closed to vary the timing 01' said ignition.

4. Ignition apparatus for an internal combustion percussive hammer having a cylinder, a piston reciprocable therein, said piston being adapted to impart impacts to a tool, and means for supplying said cylinder with a combustible charge, including: an ignition circuit for igniting said charge; a longitudinally movable plunger actuated by movement of said piston through contact with a cam suriace thereon; a pair of cooperating points in said circuit adapted to contact each other upon movement of said plunger to close said circuit; a second pair of cooperating points in said circuit, normally biased together, adapted to separate upon further movement or said plunger to break said circuit; and means for adjustingthe period during which said circuit is closed to vary the timing of said ignition.

5. Ignition apparatus for an internal combustion percussive hammer having a cylinder, a piston freely reciprocable therein, said piston being adapted to impart impacts to a tool, and means for supplying said cylinder with a combustible charge, including: an ignition circuit for igniting said charge; a longitudinally movable plunger -actuated by movement oi said piston through contact with a cam surface thereon; 'a pair oi'cooperatingvpoints in said circuit adapted to contact each other upon movement of said plunger to close said circuit; a second pair of cooperating.

points in said circuit; a movable member having mounted thereon one or each of said pairs oi points; movable means on which the other of said second pair of points is mounted, said means being so constructed as to maintain said second pair oi points in contact upon initial movement oi said member eii'ected by closing oi said first pair of points by said plunger, but to'cause said points to separate upon further movement of said member.

6. Ignition apparatus for an internal combustion percussive hammer having a cylinder, a piston freely reciprocable therein, said piston being adapted to impart impacts to a'tool, and means for supplying said cylinder with a combustible charge, including an ignition circuit for igniting said charge; means actuated by move ment of said piston for closing said circuit, said 7 means including a pair of cooperating points;

meansactuated upon further movement-of said piston for breaking said circuit, said means including a second pair of points; mounting means for one of said second pointstending to maintainsaidpointsin close relationship; andvariable stop means for varying the instant of separation oi'saidsecondpairoipointa- '1. Ignition apparatus ioran internal combused to impart impacts in a tool, and means for upplying :said cylinder with a combustible charge, including an ignition circuit for igniting said charge: a longitudinally movable plunger actuated by movement oi said piston through contactwithacamsuriacethereon; apairoicooperating points in said circuit adapted to contact each other upon'movement of said plunger to close said circuit; a second pair oi cooperating points in said circuit; a movable member having mounted thereon one oi each of said pairs of points; spring mounting means for the other 01' said-second pair of points, said spring means tending to maintain said second pair of points in contact during movement of said member eifected vby closing of said first pair oi points by said plunger; and manually adjustable stop means to vary the instant at which movement of saidspring means is arrested to separate said second p'airot points.

8. Ignition apparatus for an internal combustion percussive hammer having a; piston therein, including: a pair of cooperating ignition points having operative connections for initiating flow of ignition current upon contact thereof, at least one 01 said points being movable; actuating means for moving said movable point into and out oi contact with; the other in accordance with the reciprocation of said piston in the hammer; and means for-automatically adjusting the duration or flow-oi said igniti a current in accordance with the temperature I the hammer.

9. Ignition apparatus for an internal combustion percussive hammer adapted to impart impacts to a tool, and means for supplying said cylinder with a combustible charge, including: an ignition circuit for igniting said charge, said circuit including a pair of cooperatingvignition points for initiating current flow upon contact thereof; actuating means for moving one of said points into and out of contact with the other in accordance withthe reciprocation oi said piston, said actuating means being operable by'contact with said piston; and means for breaking saidcircuit after it has been closed i'or'a desired'period, said means automatically varying thelength of said period in accordance with the temperature of the hammer.

10. Apparatus oi the character claimed in claim 9, including a second pair oi points in said circuit.

11. Apparatus oi the character claimed in claim cuit and a thermally responsive .element upon which one oi said second pair of points is mounted. I

12. Ignition apparatus for an internal combustion percussive hammer having a cylinder. a piston reciprocable therein, said piston being adaptedtoimpartimpactstoatoohandmeansior ving a cylindena piston freely reciprocable therein, said piston being to close said circuit; a second pair of cooperating points in said circuit; a movable member having mounted thereon one 01 each of said pairs of points; a thermally responsive movable means on which the other of said second pair of points is mounted, said means being so constructed as to maintain said second pair of points in contact for a desired period dlu'ing movement of said member eflected by closing of said first pair of points by said plunger, whereby said period is automatically varied in accordance with the temperature of the hammer.

13. Ignition apparatus for an internal combustion percussive hammer having a cylinder. a piston freely reciprocal therein, said piston being adapted to impart impacts to a tool, and'means for supplying said cylinder with a combustible charge, including: an ignition system for igniting said charge, said system including a pair of cooperating ignition points for controlling said ignition upon a change of relationship thereof, at least one 01' said points being movable; a longitudinally movable plunger actuated by reciprocation of said piston, said plunger having one of said points mounted thereon; means whereby said plunger may continue further movement after said points have come into contact; and means for mounting said plunger in said hammer, said means being adjustable to move said plunger toward or away from said piston.

14. Apparatus of the character claimed in claim 13, wherein said mounting means for the plunger has a point thereon adapted to register with a cooperating point on said plunger when said plunger is moved to its farthest outer position by said piston.

CARL CHARLES.

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