US1803307A - Portable electric tool - Google Patents

Description

April 1931- o. P. WODACK 1,803,307

PORTABLE ELECTRIC TOOL Filed Aug. 15, 1925 2 Sheets-Sheet 1' Tn vcnib'r 0.5 can Z00 61141010,

0. P. WODACK PORTABLE ELECTRIC TOOL April 28, 193:].

2 Sheets-Sheet 2 Filed Aug. 13, 1925 Patented Apr. 28, 1931" PATENT OFFICE OSCAR P. WODACK, CHICAGO; ILLINOIS, ASSIGNOR TO WODACK ELECTRIC TOOL GOR- POBA'IION, OI CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS ron'rAistn ELECTRIC .TooL

Application flled August 13, 1925. Serial No. 49,930.

My invention relates to improvements in electric tools and has particular reference to portable-tools such as are used for drilling or breaking up stone, concrete and the like.

' The general object of the invention is to provide an electric tool which can be manufactured on a very economical basis and which is eflicient and reliable in operation.

A more specific object is to provide a novel means for applying power derived from an electric motor to the actuating spring of a working tool.

Further objects and advantages will become apparent form the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is an elevational view of a tool embodying the features of my invention.

Fig. 2 is a fragmentary view in vertical section of the tool shown in Fig. 1.

Fig. 3 is a sectional view taken along the line 3-'3 of Fig.2.

Fig. 4:.is a view taken along the line 4-4 of Fig. 1.

Figs. 5 and 6 aresectional views along the lines5-5 and 6-6 respectively of Fig. 2.

While I have shown in the drawings and will herein describe the preferred embodi ment of myinvention, I- do not intend to be limited thereby to the particular form disclosed, but aim in the appended claims to cover all modifications and alterative constructions falling within thescope of the invention.

W5 Referring to the exemplary embodiment of the invention illustrated in the drawings, 10 represents a tubular body or casing defining a chamber in which a plunger 11 reciprocates. Theupper end of the casing is closed by a suitable plug 12 and isfitted with the usual operating handle l3which may be secured to the casing in any preferred manner. Interposed between the plug 12 and the plunger 11 is a strong coiled spring 14 d which is periodically compressed and then released to supply energy to the plunger dur ing its working stroke as will presentlybe described. I a

. The lower end of the casing 10 is fitted with a suitable operating tool 15 against which the plunger strikes at thefend of its working stroke. In the present instance a removable cap 16 is threaded on the end of the casing to receive the shank 17 of the tool and retain it in centered position. Preferably the shank 17 is surrounded by a'coil spring 18 extending between the cap 16 and a movable collar 19, which spring serves to sustain and cushion the blows of the plunger when the tool is running idle.

' Power to compress the actuating spring 14 is derived from a suitable electric motor 20 mounted adjacent the casing 10 in any preferred manner. In the present instance the motor is supported by a housing 21 with the axis of a shaft 22 extending parallel to the casing 10. To this end the motor casing is formed with a flange 24 which may be suitably secured to the housing by screws 25, a bearing plate 26 being placed between the two parts. The housing 21 in the form shown herein encircles the casing 10 and is removably clamped thereto by screws 27 extending between lugs 28 formed on split portions of the housing. 29 is an integral lug clamped to the casing 10 and joining the upper end of the motor casing with the casing 10 Thus, it will be observed that the casing 10, the housing 21. and the motor 20 can be readily disassembled to permit cleaning or repairing of the operating parts of the tool.

To sustain the end and thrust of the motor shaft both of its ends are of reduced diameter so as to provide shoulders 30 which abut against the ends of suitable thrust bearings 31. 32 is a suitable control switch for the motor. l

Means is provided for applying the power of the motor to periodically compress and re lease the actuatin spring 14. This means constitutes an important feature of the present invention and comprises a worm 33 and a 'worm wheel 34 connecting the motor shaft with a toothed wheel. 35 within the housing 21. The toothed wheel and the worm wheel are both keyed to a shaft 36 which is journalled at its opposite ends in bracket arms 37 integrally formed on the bearing plate 26. The worm 33 is fixed to the lower end of the motor shaft in mesh with the worm wheel. 38

(see Fig. 5) indicates an extension of the forward arm 37 providing a bearing support for the extreme lower end of the motor shaft. By this arrangement the toothed wheel 85 will rotate continuously at a much slower speed than the motor shaft and with a correspondingly greater amount of power available for each revolution. The worm and worm wheel connection lends itself readily to the accomplishment of this result and permits of a compact and simple arrangement of the parts.

On rotation of the toothed wheel 35 in the direction indicated in Fig. 2, each of its teeth will be projected through a slot 39 in the easing 10 into a longitudinal groove 40 in the plunger for a certain portion of each revolution. During this movement the straight edge of each tooth will engage a shoulder 42 thereby causing the plunger to be raised and the spring 14 to be gradually compressed. As a tooth moves out of the plunger chamber, the spring will he suddenly released and the energy stored therein will be applied to the plunger which at that instant will be free to move downwardly to strike the tool shank 17. By the time the plunger has completed its working stroke, another tooth will have moved into the casing 10 and will be ready to engage the plunger for the return stroke. This cycle of the plunger will be repeated for each tooth on the wheel 35.

As a means for preventing mutilation of the parts in case the spring 14 should break and the toothed wheel continue its operation, I provide a safety device in the form of a screw 43 extending into the groove 40. This screw is adapted to engage a shoulder 44 and thereby prevent the movement of the plunger any substantial distance beyond the normal limit of its return stroke. The screw 43 also serves to prevent turning of the plunger within the casing in case one of the teeth on the wheel 3i should break off.

The shoulders 42 and .14 defining the ends of the slot 40 are preferably spaced equidistant from the ends of the plunger. Thus, when the shoulder 42 becomes worn, the plunger may be removed and reversed so that the unworn shoulder 44 will then be in posi tion to be engaged by the toothed driving wheel.

It will be noted that in the arrangement which I employ natural cooling of the motor windings is not provided for. I have, therefore, mounted a suitable exhaust fan impeller on the motor shaft just above the bearing plate 26. This fan is adapted to draw air through perforations 45 in the top of the motor casing and deliver it through a flexible tube 46 to a nozzle 47 secured to the working tool 15. The fan thus effects a forced cooling of the motor and serves to blow away chips and dust accumulating around the tool.

It will be apparent that the tool which I have provided is of extremely rugged eonstruction and capable of withstanding the wear and tear incident to the service use of a device of this kind. It comprises a minimum number of parts which are compactly arranged and adapted to be readily disassembled for replacement or repair. Because of its simplicity and the advantageous arrangement of its parts, the tool can be manufactured and operated at a very low cost.

I claim as my invention:

1. In a portable electric tool, a casing, a plunger adapted to reciprocate therein, a spring acting on said plunger, a rotary actuating device adapted to engage said plunger and compress said spring, an electric motor for driving said actuating device, a housing mounted on said casing, and a member removably supported upon said housing including supporting means rigid therewith and projecting therefrom into said housing for supporting said actuating device in said housing.

2. In a portable electric tool, a casing, a plunger adapted to reciprocate therein, a spring acting on said plunger, an actuating device adapted to engage said plunger, a housing mounted on said casing, a plate removably mounted on said housing, bracket arms depending from said plate and rotatably supporting said device within said housing, and an electric'motor for driving said actuating device.

3. A portable electric drill having, in combination with a casing and a plunger adapted to reciprocate therein, a housing on said casing, a pair of bracket arms removably supported by and projecting into said housing, an actuating device for said plunger rotatably supported by said bracket arms, an electric motor, and a worm and worm wheel driving connection intermediate said motor and said actuating device.

4. A portable electric tool having, in combination, acasing, a plunger adapted to reciprocate therein, a housing removably mounted on said casing, an electric motor mounted on said housing, a plate removably held between said motor and said housing, bracket arms depending from said plate, a shaft mounted on said brackets, an actuating device for said plunger rigid on said shaft, a worm wheel also rigid on said shaft, and a worm driven by said motor and meshing with said worm wheel for actuation of said device.

5. A portable electric tool having, in combination, a spring hammer with a longitudinally slotted cylindrical casing, a hammer and an actuating spring inside casing, a housing secured on the side of said casing and communicating with the slot in the casing, a motor, speed reduction gearing connected to said motor. and mounted within ahousing, and a star wheel driven by said gearing and engageable with said hammer to actuate the same, said star wheel being mounted in said casing to permit removal of the star Wheel from the housing While the hammer is assembled and while the housing is in position on said casing.

In testimony whereof, I have hereunto affixed my signature.

OSCAR P. WODACK.

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