US2162416A - Internal combustion tool - Google Patents

Description

June W, WW E. R. BODDINGHOUSE J A I INTERNAL COMBUSTION TOOL Filed Oct; 15, 1937 Patented June 13, 1939 za i si.

INTERNAL COMBUSTION TOOL Emmons R. Boddinghouse, Ehic'ago, Ill., assignor to Gas Tool Patents Corporation, a corporation of Delaware Application October 15, 1937, Serial No. 169,277

to Claims. l (01. 123-41 Thisinvention relates to an internal combustion percussive tool or hammer, and more particularly to an improved arrangement for, returning the piston of a hammer of the free piston a yp One feature of this invention is that it provides improved operation and power; another feature of this invention is the provision of a hammer having such a predetermined relationship be- 10 tween the relative weights of the parts, the hardness of the parts and the spring loading as will insure durability and most eflicient operation; yet another feature is that the life of the return springs'and associated parts is improved? other vl5 features and advantages of this invention will,

be apparent from the following specification and. the drawing, in which the figure is a vertical view, principally in section, of a complete hammer embodying the invention hereinafter described.

: The hammer disclosed herein is an improve ment upon hammers of the freepi'ston type, the general operation of which is already known in the art. The present application is a continuation in part of my application Serial No. 739,553,

25 filed August 13, 1934, which issued as Patent 2,101,608 on December 7, 1937.

The hammer isof the internal combustion type wherein a cyl nder in has a piston ll freely reciprocable therein, the hammer operating on the 80 general principles of a two stroke cycle internal combustion engine and being adapted to impart blows to a tool l2 through an anvil l3.

Additional'mech'anism and parts are provided associated with the cylinder l0 and piston l l to 35 form an operative internal combustion engine.

A combustible charge of air and vaporized gasoline, for example, is supplied from the chargeforming or fuel supply unit II to the chamber l5 7 beneath the piston, where it is partly compressed 40 by the downwardor working stroke of the piston.

Near the bottom of this stroke the charge is transferred from. the sub-piston compression space to the combustion chamber at the top of the cylinder through the transfer passage Hi. The charge is 46 then finally compressed on the upward stroke of the piston, effected by the return spring means; and is ignited by the spark plug I! at the proper time, as a result of action of the circuit breaker or timing device U, which device has. a movable 50 part driven by direct contact with a cam surface on the piston ll. Combustion of this charge drives the piston downward on its'working stroke to strike the anvil l3 and transmit a blow to the tool when it is in the working position illustrated 65 'in the drawing, the burned gases being discharged through the exhaust port I!) at the end of the stroke and the cycle then being repeated.

Handles 20 and M are provided to enable a workman or operator to properly manipulate the hammer, to spot the tool on the working point, and to lift the .hammer between operations. Starting is accomplished by manually depressing the starting rod' 22 until the piston is near the lower end of its travel, then releasing it so that the piston rises rapidly under the urging of the 10 return spring means and compresses and ignites a charge in thefiring chamber. The source of current for ignition is attached to the spark plug H and the timer [8 by appropriate lead .wires,

brought into one handle of the hammer through 16 the flexible cable 23 from an external source.

It will be seen that the hammer comprises a relatively long substantially cylindrical body having a bore extending therethrough from the top to the bottom, but being of somewhat different 20 diameters at different parts. Thebody comprises the cylinder proper ill, the anvil housing 21 and the spring housing 28. These are made as separate parts merely for manufacturing and assembling convenience, and are all concentric and 25 held rigidly together when the hammer is assembled; It will be understood that the important part is to have a long bore containing the various parts, and "cylinder" will be used hereafter to define this entire bore, rather than merely the firing chamber or cylinder proper.

The cylinder has mounted therein in its anvil housingportion, an anvil sleeve bearing 29. This sleeve provides a bearing for the anvil i3, and is a gas tight fit both with the anvil and with the 5 cylinder wall. This sleeve bearing is longitudinally movable in the cylinder, and its uppermost position, as illustrated, abuts an annular shoulder or stop member. -It will be noted that the anvil I3 is mushroomed out at the bottom to form ahead which limits the upward movement thereof. When the hammer is working the tool I2 is, as a result of pressure on the work, held upwardly in the hammer in the position illustrated. The full impact force of .the piston blow may thus .be delivered. to the tool, since the anvil has a range of longitudinal motion before it strikes the part below it. a

Immediately beneath the sleeve bearing 29 and abutting it is the follower 30. This follower surrounds the upper. portion of the tool I! and is axially or longitudinally movablein the housing 28. It is supported in a rest position against the sleeve bearing by the recoil absorbing spring 3|, which the follower and its lower end abutting the bottom of the hammer. The follower also has a reduced portion lying within the spring and movably mounted in the opening 32 at the bottom of the hammer, so that the follower is guided at each end.

The return spring means comprises a piston return spring 33 and a heavier surge cushioning spring 34 therebelow. The two springs contact each other, and the upper end of the spring 33 abuts the bottom of the piston ll, surrounding the striker portion thereof. In the operation of the device the piston is returned after the power stroke by the combined action of the springs 33 and 34 and the rebound which occurs from the impactof the striker portion of the piston upon the reduced portion of the anvil. In order that the anvil and hammer may have the necessary durability and may cause the desired rebound, they should each have a minimum hardness of 60 scleroscope or about Rockwell (1-44.

To describe the details of the hammer more fully, the particular hammer illustrated weighs about 91 pounds and delivers about 1450 blows per minute when. working. 'The piston II is about 2% inches in diameter and weighs seven pounds five ounces. It has been found that the weight of this piston should preferably be kept within a range of from four to nine pounds. piston, while it delivers more powerful individual blows, slows down the speed of the hammer so that the total work output is not as great; too light a piston, as for example a 3 pound piston in this size hammer, results in high operating speed but again less work output. The return spring means are arranged so as to be under a maximum static spring load of about '75 pounds when the springs are compressed until the striker portion of the piston is in contact with the top of the anvil II; that is, the maximum spring load referred to herein is that force in pounds required to force the piston manually down into contact with the anvil. The piston return spring means should be relatively weak, having an in crease in load of less than 50 pounds per inch of compression, and preferably even less than 25 pounds. The preferred embodiment described herewith has a piston return spring assembly which increases in load at about 16 pounds per inch of compression.

Not only is the relationship between the loading of the various springs, the rate of change thereof and the piston weightimportant, but also "the hardness of the anvil and the striker portion of the piston. I have discovered that the mainte nance of a predetermined ratio between the piston weight, the hardness of the striker portion of the piston and'of the "anvil, and the maximum spring load of the return springs is essential to efficient operation of the hammer as a whole. The scleroscope hardness of the striker portion of the piston and the anvil preferably should not fall below a. minimum of 60'scleroscope. The maximum spring load in pounds of the return springs should not exceed thirty times the weight in pounds' of the piston. When these ratios are maintained, the device will have the rigidity of action required for its work and excessive vibration will not be imparted to the entire device. There is a close relation also between the spring load and the hardness of the contacting parts. That is, if the anvil and striker portions are made harder, the maximum static load of the piston return springs must be lower and vice versa. Normal engineer- 'achieve the desired results.

A heavier ing practice indicates hardening of parts subject .to impact to a Rockwell hardness of from 0-35 to about C-42. It has been found to result in much better hammer operation and lessened spring troubles 'if the hardness of these portions is much higher than normal, at least a Rockwell hardness of C-47 about 60 scleroscope). With such a hardness the maximum static spring load when the striker portion contacts the anvil should be kept less than 30 times the piston weight to While the hardness and spring loading within these ranges gives appreciably improved results over normal practice, the best combination has been found to be an anvil and striker portion hardness within the range from Rockwell 0-57 to C-63 and a return spring means load, when the striker contacts the.

anvil, of from 8 to 15 times the weight of the piston. In' the particular hammer illustrated herewith the anvil and striker portion have a hardness of Rockwell C-60, and the spring loading is about 11 times the piston weight.

Whatever the reasons, the particular spring hardness and weight combinations described, and more particularly a loading of from 8 to 15 times the piston weight, provide a distinctly better hammer under operating conditions than those heretofore known. This arrangement causes the hammer not only to run more smoothly and with more power when working, but also with an absence of excessive vibration at all times, even when lifted. providing a much more comfortable and easier handling hammer for the operator than those heretofore used. yet sacrificing none of the working power. The older type hammers produce quite a clatter and frequent jumps when held up, with intense wracking vibration in the body, noticeably absent in the hammer constructed in accordance with the principles set out above.

While I have described and claimed 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.

I claim: 1. In an internal combustion hammer, a cylinder and a piston therein, an anvil and means supporting it below said piston, return spring means for returning the piston to firing position, the maximum load of said spring means when compressed by said piston until the latter touches the anvil not exceeding thirty times the weight of the piston, the anvil striking portion of the piston and the anvil having a minimum hardness of sixty scleroscope,

2. An internal combustion hammer of the character described. including: a cylinder; a piston freely reciprocable therein, said piston having a striker portion; an anvil adapted to receive blows from said striker and transmit them to a tool when said tool is in working position, said anvil and striker portion having a minimum hardness of Rockwell 0-44; means for supplying a combustible charge to said cylinder to effect downward movement of said piston; and return spring means for returning the piston to firing position, the maximum static load of said spring means not exceeding thirty times the weight of the piston.

3. An internal combustion hammer of the character described, including: a cylinder; a piston freely reciprocable therein, said piston having a striker portion; an anvil adapted to receive blows from said striker and transmit them to a tool when said tool is in working position, said anvil and striker portion having a minimum hardness of Rockwell -44; means for'supplying a combustible charge to said cylinder to effect downward movement of said piston; and return spring means for returning the piston to firing position, the maximum static load of said spring means being from eight to fifteen times the weight of the piston.

4. An internal combustion hammer of the character described, including: acylinder; a piston freely reciprocable therein, said piston having a striker portion; an anvil adapted to receive blows from said striker and transmit them to a tool when said tool is in working position, said anvil and striker portion having a minimum hardness of Rockwell C-44; means for supplying a combustible charge to said cylinder to eflect downward movement of said piston; and return spring means for returning the piston to firing Y position, the maximum static load of said spring means being about eleven times the weight of the piston.

5. An internal combustion hammer oi the character described, including: a cylinder; a piston freely reciprocable therein and having a weight of from four to nine pounds, said piston having a striker portion; an anvil adapted to receive blows from said striker and transmit them. to a tool when said tool is in working position;

, means for supplying a combustible charge to said cylinder to eflect downward movement of said piston; and, return spring means for returning the piston to firing position, the maximum static load oi said spring means being within the range of ircm eight to fifteen times the weight of the piston.

6. Ahammer of the character claimed in claim 5, wherein said piston has a weight of about seven pounds. 5 a

7. An internal combustion hammer of the character described, including: a cylinder; a piston freely reciprocable therein; said piston having a striker portion; and an anvil adapted to receive blows from said striker and transmit them to a tool when said tool is in working position, said anvil and striker portion having a hardness within the range of Rockwell C57 to 'C-63.

8. An internal combustion hammer of the character described, including: a cylinder; a piston freely reciprocable therein, said piston having a striker portion; return spring means for said piston; and an anvil adapted to receive' blows from said striker and transmit them to a tool when said tool is in working position, said anvil and striker portion having a hardness within the range of Rockwell C-5'l to C-63, the maximum static load or said spring means being within the range of eight to fifteen times the weight of the piston.

9. An internal combustion hammer oi the character described, including: a cylinder, a piston freely reciprocable therein, said piston having a striker portion; an anvil adapted 'to receive blows from said striker and transmit them to a tool when said tool is in working position, said anvil and striker portion having a hardness of about Rockell C-fiO; means for supplying a combustible charge to said cylinder to effect downward movement of said piston; and return spring means for returning the piston to firing position, the maximum static load of said spring means being about eleven times the weight of the piston.

10. A hammer of the character claimed in claim 9, wherein said piston has a weight of from four to nine pounds.

EMMONS R. BODDINGHOUSE.

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