US2468020A - Internal-combustion device - Google Patents

Description

A ril 26, 1949. F. N. BA RD 2,468,020

INTERNAL-COMBUS'IIQN DEVICE Filed uamh- 28. 1946 4' sheets-sheet 1 April 26, 1949. -BARD 2,468,020

INTERNAL-COMBUSTION DEVICE File d March 2a, 1946 4 Sheets-Sheet 2 April 26, 1949. F. N BARD 2,468,020

I INTERNAL-COMBUSTION DEVICE" Filed March 28,, 1946 4 SheetsSheet 4 1770 677752".- rzc ((5 WWW,

prises the main body Patented Apr. 26, 1949 UNITED STATES PATENT orrica INTERNAL-COMBUSTION DEVICE Francis N. Bard, Highland Park, 111. Application March 28, 1946, Serial No. 657,650

8' Claims. (Cl. 123-449) This invention relates to an internal combustion device, and more particularly to an internal combustion percussive device of the free-piston type and to ignition means therefor including a magneto.

Internal combustion hammers of the free-piston type have no crank shaft and, because of this, and because of the terrific vibration present in such a hammer, it has heretofore been considered impossible to use a magneto for generating the ignition spark. I have devised, and am here disclosing, magneto and ignition arrangements which are capable of operation by means other than a rotating crank shaft, which are properly timed and related to piston movement despite the absence of a crank shaft, and which are sufficiently rugged in construction to withstand thevibration present in a type.

This application is one of two copending companion applications relating to magneto ignition of an internal combustion hammer, my other companion application being Serial No. 657,649, filed March 28, 1946.

Various features and advantages of this invention will be apparent from the following specification and the drawings, in which:

Figure 1 is a sideelevational view, partly in vertical section, of a free-piston internal combustion hammer incorporating one embodiment of my inventions; Figure 2 is an enlarged view of the magneto and actuating assembly and associated hammer parts, partly in vertical section and partly in' side elevation; Figure 3 is a horizontal sectional view along the line 3-3 of Figure 2; Figure 4 is a horizontal sectional view along the line 4-4 of Figure 2; Figure 5 is a fragmentary vertical sectional view along the line 5-5 of Figure 4, with the rollermovement schematically illustrated, Figure 6 is a schematic view showing the ignition circuit; and Figure 7 is a partial vertical sectional view internal combustion hammer including a modified embodiment of my inventions.

.The internal combustion percussive device with which I am here concerned is of a type providing a self-contained gasoline powered device for such purposes as pavement breaking, rock drilling, tamping, and thelike. The cylinder l0 comportion of the device and has a piston-hammer ll freely reciprocable therein, being driven downwardly by the explosion of a combustible charge thereabove and being returned by the action of a return spring assisted by rebound. Hammers of this general type, but

hammer of the free-piston of the upper end of an with battery ignition, have been made and sold for some years by my company, and the description of the general principles of such hammers and of their operation will be kept brief since reference may be made to issued patents to supplement the present disclosure if desired, as for ekample Mould Patents 1,868,754 and 1,997,072 and Charles Patents 2,180,034 and 2,275,285, these being merely representative examples of the many issued patents on such hammers.

Briefly to describe the operation of the hammers here disclosed in Figures 1-5, gasoline in a tank I2 is mixed with air in carburetor l3 and delivered to the chamber l4 beneath the piston, where it is partly compressed by the downward stroke thereof. Near the bottom of the'working stroke of the piston the charge'is transferred from this lower space to the combustion space above the piston, at the top of the cylinder [0, through transfer passages which preferably include passageway portions in the piston II and the portion IS in the cylinder ID. The combustible charge thus provided in the upper end of the cylinder is then further compressed on the up ward stroke of the piston, effected primarily by the return spring l6, and at a proper time with respect to piston movement this charge is ignited by causing a spark to jump across the electrodes of the spark plug ll. Combustion of thischarge drives the piston downward on its working stroke, thelower end of the piston eventually striking the top of the anvil It in the anvil housing l9 and the blow thus being transmitted to the tool 20. As

-port 2|,

the piston nears the lower end of its travel the burned gases are discharged through the exhaust a fresh charge transferred to the space above the piston, and the cycle of operation repeated.

Handles 22 and 23- are provided to enable a workman to spot the tool in a desired working point, to maintain the hammer in operative position during working thereof, and to lift the hammer between operations. Starting is accomplished by manually depressing the starting rod 24, normally biased to the position shown by the spring 25, until the piston H is near the lower end of its travel, then releasing it, then again pushing down on the starting rod and releasing it, an explosion taking place as soon as a charge has been drawn into the sub-piston compression space and transferred to the combustion space above the piston. The means for providing ignition of the combustible charge in properly timed relation to piston movement and in a manner obviating the necessity for cables. storage batteries, and the like, comprises the improvement to which this and my companion application are directed, and these will now be more particularly described.

Referring now more particularly to Figures 2-5, inclusive, a magneto identified in general as A will be seen to be mounted on the side wall of the cylinder I, this magneto comprising as its principal parts an outer permanent magnet or pole assembly 26, a rotatably or oscillatably movable armature member or rotor 21, and a coil 28 wound therein, this coil comprising a primary 28a and a secondary 28b in accordance with the practice followed in more conventional rotary magnetos.

The rotor 21 of the magneto in this case is rigidly mounted on a rotor shaft 29 having its axis vertical (1. e., parallel to the axis of the piston II) The actuating means for the magneto includes a member 30 rigidly mounted on and keyed to the lower end of the shaft 29, this member 30 being mounted in an appropriate slot lfla in the side wall of' the cylinder, and having its inner end extending into a vertical slot Ila in the piston. The inner end'of the member (i. e., the end lying in the slot I la in the piston) is provided with a roller 3|. The piston has pivotally mounted in its side wall in the slot Ila a do or member 32 so mounted as to have pivotal movement about the pin portion 320. and to have this movement limited to about 15 or 20 by the pin 32b in the small arcuate slot llb in the wall of the piston. The member 30, and thus the shaft 29, are normally biased to a central position by biasing means best seen in Figure 4 and comprising the axially movable round headed pins 33 and 34 urged against the side of the member 30 by the similar springs 35 and 36.

Referring now more particularly to Figure 5, it will be seen that downward movement of the piston results in relative movement between it and the roller 3| which causes such roller 3| to be deflected to the left as shown in various dotted line positions, the upper end of the member 32 being pivoted to the farthest right limit of its movement, referring to the particular position of the parts as viewed in Figure 5, this position being shown in dotted lines. While the member 32 is preferably not quite vertical in this position, it is provided with a tapered left-hand edge near its upper end, as shown, so that the latter part of the relative movement between the piston and the roller 3| is straight until the roller passes over the upper tip of the member 32, whereupon the member 32 drops to the left and downwardly to the position shown in full lines in Figure 5-. Upward movement of the piston on its return thereupon deflects the roller 3| to the right (again speaking as viewed in Figure 5), the positions of the roller 3| during such upward movement of the piston being shown 'in dotted lines to the right of the member 32, which will be understood to now be in full line position. When the piston has moved up to near the end of its stroke, the roller 3| suddenly takes a rather sharp and quick movement to the left beneath the member 32 under the influence of the spring 36, the roller no longer being held to the right by the member 32. This sudden spring urged movement of the roller 3|, the member 30 on which it is mounted and the rotor shaft 29 of the magneto is more rapid than could be effected by a cam shoulder on the piston without pounding the parts to pieces under the very high speed of operation in a hammer of this type, usually in the order of 4 1500 reciprocations per minute of the piston. This relatively rapid although angularly small movement of the rotor tends to change the flux conditions through the rotor quite rapidly.

Referring now more particularly to Figures 3 and 6, the outer pole construction of the rotor is such that it is provided with two poles of oD- posite polarity, as for example a pole 26a of north polarity and a pole 26b of south polarity. In the initial position of the arm 30, slightly to the left of the central position (i. e as shown in Figure 4) the armature 2'! stands in a position slightly counter-clockwise of the neutral position shown, with the right-hand end 21a of the armature in good magnetic relationship to the pole 26a, and with the left-hand end 27b of the armature overlapping the pole 26b by at least 10 and spaced from the pole 26a. This results in magnetic flux passing through the armature in such manner that the end 21a is of a north polarity and the end 21b of a south polarity. As the piston moves down therotor isturned 15 or 20 clockwise (again speaking with respect to Figure 3) of this position until the end 211) of the armature is in magnetic relationship with the pole 26a and spaced from the pole 26b, while the other end 21a of the armature is in good magnetic relation with the pole 26b and spaced from the pole 26a. When the roller 3| gets beneath the lower end of the member 32 on the side of the piston, the movement of the actuating means, under the influence of the springs, causes a sudden counter-clockwise movement of the rotor for 15 or 20, back to the initial position described, this resulting in a complete reversal of flux through the armature. At the moment when the reversal of flux through the armature creates the maximum current in the primary 28a, (now referring particularly to Figure 6) a stud member 38 mounted on and moved by the rotor shaft 29 contacts a spring member 39 and effects separation of the breaker points wand 40?), the sudden collapse of field around the primary then creating a surge of high potential energy (of the order of 10,000 volts) in the secondary 28!), this being delivered through the high potential cable 4| to the hot" electrode of the spark plug H, the central elec-' trade. This surge of energy causes sparking between the electrodes of the spark plug to ignite the combustible charge in the cylinder and drive the piston down on its next working stroke. The ignition circuit is completed through ground in conventional manner (in this case the body of the hammer), and a condenser 42 serves to minimize arcing at the breaker points. The entire assembly provides a magneto arrangement which can be very satisfactorily actuated from a free piston without undue wear and pounding on the parts, with an ignition system which can be completely sealed in so that the magneto is protected from dust and the like. This provides a satisfactory and usable ignition system for an internal combusion hammer of the free-piston type, actuating a magneto without the presence of a crank shaft and being capable of withstanding the tremendous vibration present in such a hammer. The advantages of a self-contained ignition system of this type are obvious as it obviates the necessity for storage batteries and cables for ignition power, as has heretofore customarily been the case.

Another embodiment of my inventions providing magneto ignition for an internal combustion hammer of the free-piston type is illustrated in Figure '7. In order to keep this specification as brief as possible consistent with a good disclosure,

reference numerals 50 higher than those hereto fore used will be applied to parts analogous to those described in connection with Figures 1-6, so that reference back to the earlier portions of the specification may be made if desired to supplement the description of the form partially illustrated in Figure 7.

The hammer body again comprises a cylinder here identified as 60, this cylinder having a piston BI freely reciprocable therein, a combustible charge being supplied to the space above the piston and ignited at an appropriate time by ignition means including the spark plug 61, this resulting in the downward or working stroke of the piston, the return stroke being effected by a return stroke or rebound. In this case the magneto, indicated in general as B, is mounted in the upper part of the hammer and is of the type including a laterally or lineally movable armature 11 associated with a pole structure 16 of the permanent magnet type and providing pole faces 16a '6 member IN. The lower end of the movable member I is provided at one side here shown and 16b, this type of magneto being analogous,

.to that described more fully in my above-menmagnetic polarity, the armature in the position shown will have its right-hand end (speaking With respect to the position in which the parts are viewed in Figure 7) of a south magnetic polarity, the return magnetic circuit being through the body of the hammer; whereas when the armature member move upwardly until it has a portion closely adjacent the pole face 16a and is spaced from the pole face 16b, the righthand end of the armature will have a north polarity and the flux conditions will be reversed. This rapidly changing flux condition results in creation of a substantial current in the primary of the coil 18, which is quickly dropped from maximum to zero by .opening of the breaker points to be hereafter described, resulting in the high voltage output from the secondary.

The armature I1 is mounted on a sleeve mem- I ber I00 vertically slidable on a tube member IOI, this member in turn being vertically or longitudinally movable in suitable bearings I02 and I03 to the hammer body and having its lower end in constant engagement with the piston 8| to move therewith, as by being welded to the piston head. The starting rod 24, normally biased to the position shown in the drawings by the spring 25, extends down through this tube member IOI so that starting movement of the piston may be effected when desired. The mounting member I00 also carries the'movable breaker point 90a of the pair of breaker points including the other point 902), this being mounted on a vertically reciprocable stud I04" normally biased upwardly by the spring I05, the limit of upward movement of this member being determined by the position of the nut I04a adapted to strike the bottom of the block I06 in which the stud I04 is movably mounted. The limit of movement of the point 901) is so adjusted that as the member I00 moves upwardly the armature member 11 has moved away from the pole face 16b and into magnetic relationship with the pole face 16a when the points separate, so that opening of the circuit takes place at a time of maximum current generation in the primary of the magneto coil.

The mounting member I00 is normally urged upwardly by a spring I01 working against another upper spring I08 above the armature I7 and between it and a collar IOIb on the tube as the right side) with a shoulder adapted to be engaged by a latch member I00 biased inwardly by means here shown as a leaf spring IIO, this latch member being pivotally mounted on the pin III and bearing a roller II2'in a slot I0ld in the tube member IOI, this slot having a lower angularly arranged actuating shoulder IOIa.

Downward movement of the piston BI carries the tube member IOI with it, downward move ment of the collar IOIb creating sufficient com-- pression force in the spring I00 to compress the spring I01 sufficiently to bring the parts to the position shown in Figure 7, with the member I00 helddown by the latch member I09. When the working stroke of the piston has been completed and it starts its return movement, no movement of the member I00 and the parts mounted thereon takes place during the major portion of the upward movement of the piston, the only thing taking place during this time being a reduction in the compression force of the spring -I08 until there .is practically no compression left in this spring. As the piston 6| approaches the top limit of-its movement the shoulder portion IN a of the slot engages the roller H2 and moves the latch member I09 out of latching engagement, whereupon a very rapid upward movement of the armature 11 takes place as a result of the force stored in the spring I01, this resulting in generation of the desired primary current in the mag- .neto' and separation of the breaker points at the appropriate interval to provide a high potential output supplied to the spark plug 61 and ignition of the charge in the cylinder.

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 thespirit and scope of the invention as disclosed in the appended claims.

I claim:

1. An internal combustion device of the freepiston type, including: a cylinder adapted to have a combustible charge therein; a piston freely reciprocable therein; electrical ignition means in one end of the cylinder; a magneto for generating a spark at said ignition means, this magneto including a movable armature; and an actuating arrangement for the magneto including an operating member having a portion in engagement with said piston at all times during its reciprocation and a spring for effecting movement of the armature, when the piston approaches said end of the cylinder, at a more rapid rate than would be effected by said operating means.

2. An internal combustion percussive device of the free-piston type, including: a cylinder adapted to have a combustible'charge therein; a piston freely reciprocable therein; electrical ignition means in one end of the cylinder; a magneto for generating a spark at said ignition means, this magneto including a movable armature; and actuating means for the magneto including operating means in engagement with said piston at all times during its reciprocation and spring means for eifecting movement of the armature, when the piston approaches said end of the cylinder,'at a more rapid rate than would be effected by said operating means. 4

3. An internal combustion percussive device of the free-piston type, including: a cylinder adapted to have a combustible charge therein; a piston freely reciprocable therein; electrical ignition means in one end-of the cylinder; 9. magneto for generating a spark at said ignition means, this magneto including a movable armature; and actuating means for the magneto including operating means in engagement with said piston at all times during its reciprocation and spring means for effecting movement of the armature, when the piston approaches said end of the cylinder, at a more rapid rate than would be efat all times during its reciprocation and spring means for effecting movement of the armature,

when the piston approaches said end of the cylinder, at a more rapid rate than would be effected by said operating means, this actuating means including a member movably mounted in a side wall of the cylinder and a member movably mounted on the piston.

5. An internal combustion percussive device of the free-piston type, including: a cylinder adapted to have a combustible charge therein; a piston freely reciprocable therein; electrical ignition means in one end of the cylinder; a magneto for generating a spark at said ignition means, this magneto including a movable armature; and an actuating arrangement for the magneto including an operating member having a. portion in engagement with said piston at all times during its reciprocation and a spring for effecting movement of the armature, when the piston approaches said end of the cylinder, at a more rapid rate than would be effected by said operating means, this actuating arrangement including a member movably mounted in a side wall of the cylinder for pivotal movement about an axis parallel to that of the cylinder and a member mounted on the piston for limited pivotal movement about an axis tranverse to that of the cylinder and adapted to be engaged by an end of the first mentioned member.

6. An internal combustion percussive device of the free-piston type, including: a cylinder adapted to have a combustible charge therein; a piston freely re'ciprocable. therein; electrical ignition means in one end of the cylinder; a magneto for generating a spark at said ignition means, this magneto including a movable armature; and actuating means for the magneto including operating means in engagement with said piston at all times during its reciprocation and spring means for effecting movement of the armature, when the piston approaches said end of the cylinder, at a more rapid rate than would be effected by said operating means, this actuating means including a member connected to said piston and longitudinally movable through an end wall of Said cylinder.

7. An internal combustion percussive device of the free-piston type, including: a cylinder adapted to have a combustible charge therein; a piston freely reciprocable therein; electrical ignition means in one end of the cylinder; a magneto for generating a spark at said ignition means, this magneto including a movable armature; and actuating means for the magneto including operating means in engagement with said piston at all times during its reciprocation and spring means for effecting movement of the armature, when the piston approaches said end of the cylinder, at a more rapid rate than would be effected by said operating means, this actuating means including a member connected to said piston and longitudinally movable through an end wall of said cylinder and latch means adapted to be tripped by said longitudinally movable member.

8. An internal combustion percussive device of the free-piston type, including: a cylinder adapted to have a combustible charge therein; a piston freely reciprocable therein; electrical ignition means in one end of the cylinder; a magneto for generating a spark at said ignition means, this magneto including a movable armature; a spring for effecting movement of the armature; latch means for the spring; and an operating member having a portion in engagement with said piston at all times during its reciprocation, the construction and arrangement being such that the operating means sets and latches the spring in one direction of piston movement and trips the latch in the other direction of piston movement when it approaches said end of the cylinder,

FRANCIS N. BARD.

REFERENCES CITED The following references are of record in the file of this patent:

, UNITED STATES PATENTS Fitch NOV. 2, 1943

Images