US2175741A - Timer for internal combustion hammers - Google Patents

Description

' 0% 19395 c L, CHARLES TIMER FOR INTERNAL COMBUSTION HAMMERS Filed Dec. 51, 1957 Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE THMER FOR INTERNAL COMBUSTION HAMMER/S Delaware Application December 31, 1937, Serial No. 182,867

7 Claims.

This invention relates to internal combustion percussive devices, and more particularly to ignition apparatus therefor.

One feature of this invention is that it provides means for varying the time of commencement of ignition; another feature of this invention is that it provides improved mounting means for the ignition points; still another feature of this invention is that the relationship of the points may be readily and conveniently set, without dismantling the ignition apparatus, to determine the time of initiation of ignition with respect to reciprocation of the piston in the hammer; other features and advantages of this invention will be apparent from the following specification and the drawing, in which:

Fig. 1 is a fragmentary sectional view of the hammer, disclosing the ignition timing apparatus in detail; Fig. 2 is an elevation of the timer housing and mounting; Fig. 3 is a view, partly in section, along the line 3-3 of Fig. 2; Fig. 4 is an elevation of the timer housing and mounting of another modification-of, this invention; Fig. 5 is a vertical sectional view along the line 5-5 of.

5 Fig. 4; Fig. 6 is a view along the line 6-6 of Fig. 4, only partly broken away; and Fig. 7 is a view, partly in section, along the line l-'l of Fig. 5.

The present application is a continuation in part of my previous application, Serial No.

135,185 filed April 5, 1937. The ignition apparatus only is illustrated herein. The complete hammer is shown in my previously-mentioned application, this hammer being of the same fundamental type as that shown in Mould Pat- 'ent 1,997,071, or Saunders Patent 1,813,513.

The internal combustion hammer or percussive tool of the type for which this ignition apparatus is designed, illustrated more fully in my above-mentioned application, has a cylinder with a piston hammer freely reciprocable therein and adapted to impart blows to a tool at t .2 bottom of the hammer, being returned after such blow by a piston return spring assembly. The hammer is provided with a chargaforming device comprising a tank for liquid fuel, a carburetor, and the necessary manifold passages enabling a combustible charge to be delivered to the combustion chamber above the piston in accordance with known two-cycle engine practice.

' The hammer is provided with an ignition system including a conventional spark plug, and ignition or timing apparatus it. A battery or other source of current and a buzzer-operated spark coil is connected, in accordance with known practice, to the timing apparatus and the spark plug. It will be noted that the piston I 1, adapted to reciprocate within the cylinder I0, is provided with a cam surface 22 adapted to actuate a cam follower or plunger in the timer 19.

In order to secure eflicient operation of an 5 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, overheat- 10 ing, and other troubles; and too late ignition results in poor combustion efficiency, 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 tempera- 15 ture 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.

In the particular timer illustrated in Figs. 1 to 3, the cylinder H! is provided with an opening 23 2Q 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 longitudinally movable plunger 25 having a roller 21 25 mounted on a pivot shaft ill on the inner end of the plunger 26 adapted to contact the cam surface 22 on the piston. A coil spring 28, axially disposed with relation to the plunger, biases or urges it against the piston, so that reciprocation 30 or movement of. the piston in the cylinder effects longitudinal movement of the plunger 26. The sleeve 24 is provided with a slot H to permit free movement of the pivot shaft 10, and thus of the plunger 26, with respect to it. 35

The plunger 26 has movably mounted therein and coaxial therewith a second longitudinally movable plunger 29. The inner end of the plunger 29 is provided with a stop 3!] adapted to contact a shoulder on the plunger 26 to prevent 40 outward movement of the second plunger with respect to the first. A coil spring 3| surrounds the second plunger and lies between a shoulder thereon and a shoulder on the plunger 26, yieldingly urging the second plunger outwardly with 45 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 3 and the roller 21, so that the plunger 26 may continue to move outwardly as a result of movement of the piston even though the second plunger 29 has ceased outward movement provided such furthermovement does not exceed the distance between the stop 30 and roller 21. 55

A pair of cooperating ignition points 32 and 33 are provided. The point 33 is adjustably 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 32 is mounted on a member 34 passing through insulated washers 35 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.

The points 32 and 33 are operatively 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 40. The point 33 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 from falling out of place when the nut is slightly loosened by the shoulder portions engaging the washer.

The slot 1| is, of course, deeper than the amount of movement of the pivot shaft 10 as a result of the effect of the cam surface on the roller 2'! during reciprocation of the piston. Outward movement of the roller, pivot shaft, and plunger 26 carries the second plunger 29 along until the point 33 contacts the fixed point 32. Contact of these two points stops further outward movement of. the plunger 29; but it does not stop further outward movement of the plunger 26 under the influence of further movement of the cam surface with respect to the roller 21, since the plunger 29 is adapted to telescope further within the plunger 26 against the bias of the spring 3|. That is, the two plungers maintain the relation illustrated during movement until the points contact each other; and further movement of the plunger 26 is thereafter permitted by a change in relationship between the two plungers.

The springs providing the necessary bias on the two plungers are here shown as nested coil springs in substantially coaxial relationship. The spring 3| is of lighter construction than 28, 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 surface. The particular arrangement shown has been found to be very rugged as well as efiicient. The plungers and springs are so arranged that the terrific vibration of the hammer when in operation causes little or no wear and difficulty with the parts. The springs particularly have been found to stand up much better than flat springs of various types originally used in the hammers.

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 25 are 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 these shims 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 33 necessary to avoid intermittent separation of the point from vibration and spring surge during the period it is desired to have them stay closed. That is, if the points just barely touch and then stay in that position for an appreciable time interval, surges in the springs 28 and 3|, vibrations in the body of. the hammer, or both, may cause the points to separate momentarily and thus interrupt ignition. Where there is considerable overtravel of the first plunger 28 the spring 3| is put under sufficient tension to insure that the points 32 and 33 remain in contact during the interval that contact is desired. In the particular embodiment of this invention illustrated in Fig. l, for example, there is about forty-seven thousandths of an inch difference 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 overtravel 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 8| of the plunger 26 is arranged to be about forty-five thousandths of an inch from the outer face 82 of the flat portion of the member 24 when the member 26 abuts the shoulder 83. 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 high point 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 remove shims beneath the fiat portion of the member 24 until the outer surface 8| of the plunger 26 is flush with the surface 82. This makes a very convenient assembly or field adjustment, and one which is independent of wear on the cam surface or roller.

The housing 38 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 contains a supply of relatively volatile inflammable fluid, 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. 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.

Another modification of this invention is illustrated in Figs. 4 to 7. While this is generally analogous to the modification shown in Figs. 1 to 3, and just described, it differs therefrom in several important respects. In the modification now being discussed the cylinder wall has a cylindrical bearing portion 43 mounted therein and fastened by any convenient means, as by the bolts 47. This bearing member 46 comprises a solid cylindrical portion received within the cylinder, and a split sleeve portion on the exterior, or end farthest from the cylinder 45. This split portion comprises two halves 48 and 49, adapted to be drawn together by any convenient means, as the studs 50.

The member 46 has mounted therein, in the portion within the cylinder, a plunger adapted to be longitudinally moved as a result of contact of the roller 52 with the cam surface on the piston 53, the roller being mounted on a pivot shaft 72 rotatably mounted in the end of the plunger 5! and movable in the slot 13. This plunger has mounted therewithin, and longitudinally movable with respect thereto, a second plunger 54. Coil spring 55 urges the plunger 5i against the cam surface on the piston; and coil spring 56 urges the second plunger outwardly. This plunger, as in the previous timer, carries a contact point 51.

The other contact point 58 is carried by a housing member 59, this member being here shown as substantially cylindrical in shape and as having an opening 69 therethrough, so placed that the points are visible therethrough. As in the preceding modification, outward movement of. the

plunger 5! as a result of the effect of the cam surface on the roller 52 carries the plunger 54 along until engagement of the points 5'! and 58; and thereafter further outward movement of the plunger 5! is permitted by telescoping movement of the plunger 54 within the plunger 5|.

The point 58 is fixedly mounted in the member 59, but this latter member is slidably mounted within the split sleeve bearing formed by the two parts 48 and 49. These parts are so arranged that, when the studs 50 are loosened, the member 59 may be moved toward or away from the hammer, and thus the point 58 is adjusted with respect to the point 51, so that the time of change of relationship of the points with respect to reciprocation of the piston may be set as desired. This desired setting may be determined by running the hammer, or by setting the piston therein at a predetermined position and then spacing the point 58 a predetermined distance from the point 51. The provision of the opening 63 enables a gauge to be inserted, if. desired, to set the points a specific distance apart at a given setting of the piston. When the desired setting has been secured it is only necessary to draw up the studs 50 to lock the member 59 in place.

It is thus apparent that a very convenient and ready means of setting the timing of hammers of this type is secured. The apparatus is such that the timing may be readily set on the job, with any standard wrench which will actuate the studs 55; and the fact that the studs may be caused to give any desired frictional grip on the member 59 enables it to be worked in, by hand, only a thousandth of an inch or so at a time.

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 appended claims, in which it is my intention to claim all novelty inherent in my invention as broadly as permissible, in view of the prior art.

I claim:

1. 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 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 of said points being movable; a longitudinally movable plunger actuated by reciprocation of said piston; and means on said plunger longitudinally movable with respect thereto and carrying one of said points, whereby said plunger is effective to move said one point toward the other and to continue further movement after said points have come into contact.

2. Apparatus of the character claimed in claim 1, wherein said last mentioned means comprises a member slidably mounted in said plunger and a coil spring biasing said member with respect thereto.

3. Ignition appartus 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 system for igniting said charge, said system including a pair of cooperating ignition points for controlling said ignition upon a change of relationship thereof; a longitudinally movable plunger actuated by reciprocation of said piston through contact with a cam surface thereon, said plunger being biased against said surface by a coil spring; a second longitudinally movable plunger slidably mounted in said first plunger, said second plunger carrying one of said points, whereby said first plunger is effective to move said point toward the other; means carried by said cylinder on which said other point is mounted, said means permitting adjustment of the position of said other point to vary the timing; and a coil spring between said two plungers, whereby further movement of said first plunger is permitted after said points have come into contact.

4. Ignition apparatus for an internal combustion percussive hammer having a piston reciprocable therein, including: a pair of cooperating ignition points having operative connections for controlling ignition current, at least one of said points being movable; actuating means in said hammer for moving one of said points toward and away from said other point in accordance with the reciprocation of said piston in said hammer, whereby said points are adapted to be in closed or separated relationship; and relatively large and heavy means carrying the other of said points, said means being readily adjustable with respect to said hammer for varying the time of change of relationship of said points with re spect to reciprocation of said piston.

5. Ignition apparatus for an internal combustion percussive hammer having a piston reciprocable therein, including: a pair of cooperating ignition points having operative connections for controlling ignition current, at least one of said points being movable; actuating means in said hammer for moving one of said points toward and away from said other point in accordance with the reciprocation of said piston in said hammer, whereby said points are adapted to be in closed or separated relationship; a relatively large and heavy member carrying the other of said points; and means on the hammer in which said carrying member is slidably mounted for movement toward and away from said hammer,

whereby one of said points may be adjusted with respect to the other for varying the time of change of relationship of said points with respect to reciprocation of said piston.

6. Apparatus of the character claimed in claim 5, including means for locking said carrying member in a desired position in said mounting means.

7. 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 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 of said points being movable; a longitudinally movable plunger actuated by reciprocation of said piston; means on said plunger l0ngitudinally movable with respect thereto and carrying one of said points, whereby said plunger is effective to move said one point toward the other and to continue further movement after said points have come into contact; a member carrying the other of said points; a split sleeve on the hammer, said carrying member being mounted therein for slidable movement toward and away from said hammer, whereby the position of the point carried by said member may be adjusted with respect to the other point for varying the time of change of relationship of said points with respect to reciprocation of said piston; and means for contracting said sleeve to lock said member against movement therein.

CARL L. CHARLES.

Images