Screwdriver Attachment

Abstract

A screwdriver attachment which can be quickly mounted on and removed from the driving end of a screwdriver shank comprising a tubular structure having openings at its opposite ends. The opening at the forward end is tapered inwardly so that it can be seated about and centered on the head of a screw, and the circular opening at the rearward end fits loosely about the shank of a screwdriver bit. A spring is disposed in the bore of the structure and is held between its two ends. A clutch member having a ring configuration is placed between the inward end of the cylindrical structure and the spring and has a plurality of resilient fingers extending from its inner surface towards the rearward end to provide a slip clutch engagement with the shank of the screwdriver bit.

Description

BACKGROUND OF THE INVENTION

This invention relates to a screwdriver attachment for guiding the driving end of a screwdriver shank into engagement with the kerf of screws and holding it in place therewith.

It is characteristic of screwdriver attachments that they are permanently mounted on the driving end of the screwdriver shank, which prevents the user from having the choice of operating the screwdriver without utilizing the attachment. Also, the permanent mounting arrangement is objectionable for it would be desirable to use the same attachment with a multitude of screwdriver bits.

Accordingly, one object of this invention is to provide a screwdriver attachment which can be selectively removed from the shank of a screwdriver bit.

Another object of this invention is to provide a screwdriver attachment which can be used interchangeably with screwdriver shanks having different cross-sectional shapes.

A further object of this invention is to provide a screwdriver attachment which can be quickly attached to and removed from the driving end of the shank of a screwdriver bit by means of a clutch member which grips the shank in a slip clutch arrangement.

Further objects and advantages of this invention will become apparent from the following description of the preferred embodiment and by referring to the drawings illustrating the preferred embodiment.

SUMMARY OF THE INVENTION

This invention relates to a detachable screwdriver attachment for a screwdriver bit which functions to guide the driving end of the shank into driving engagement with the kerf of a screw. The attachment comprises an elongated tubular structure having a bore formed along its length and having openings formed in its opposite ends. Extending inwardly from the opening at the outer end of the elongated structure is a tapered surface shaped to seat about the head of a screw. The opening at the rearward end of the structure is designed to fit loosely about the shank of the screwdriver bit. A spring is disposed in the bore between the inner and outer ends of the tubular structure, and a clutch member is positioned between the rearward end of the structure and the spring. The clutch member has a plurality of resilient fingers which are adapted to frictionally engage and grip about the shank with a sufficient force that the spring is compressed upon the screwdriver shank being pushed towards the outer end of the cylindrical structure. The frictional force exerted by the resilient fingers may be overcome by a pushing or pulling force exerted on the shank which is substantially greater than the inward pushing force necessary to compress the spring.

DESCRIPTION OF DRAWINGS

For a better understanding of this invention, reference is made to the following drawings, in which:

FIG. 1 is a side elevational view of the preferred embodiment of this invention with its internal parts shown in dotted lines and with the driving end of the shank of a screwdriver bit being shown prior to insertion in the inner end of the preferred embodiment and with the screwhead being shown disposed below the outer end of the preferred embodiment;

FIG. 2 is a sectional view of the elongated tubular structure;

FIG. 3 is a sectional view of the screwhead engaging member which fits in the outer end of the elongated structure of FIG. 2;

FIG. 4 is a top plan view of the clutch member which is disposed in the bore of the elongated structure shown in FIG. 1 between the inner end of the elongated structure and the spring;

FIG. 5 is a side elevational view of the member of FIG. 4; and

FIG. 6 is a cross-sectional view of the preferred embodiment of this invention shown with the driving end of a screwdriver shank inserted through the rearward end of the elongated structure and held in engagement in the kerf of a screwhead.

DESCRIPTION OF PREFERRED EMBODIMENT

There is shown in FIG. 1, a screwdriver attachment or screwhead finder 10 which is designed to be quickly mounted on the driving end 12 of the shank 14 of a screwdriver 16. The screwdriver attachment 10 is housed in an elongated tubular structure 18 having a generally cylindrical configuration as best seen in FIG. 2. The elongated tubular structure 18 is preferably formed as a one-piece molded plastic part having a knurled portion 20 on its outer surface to assist the user in gripping the attachment 10. The elongated tubular structure 18 has a bore 22 along its length and has circular openings 24 and 26 formed at its opposite ends.

In the outer or forward end 28 of the elongated structure 18, a screwhead-engaging member 30 (see FIG. 3) is mounted in the outer portion of the bore 22. The screwhead-engaging member 30 is also preferably molded plastic material having a cylindrical outer shape which fits snugly in the outer end 28 between the circular opening 26 and an annular shoulder 32 (see FIG. 2) to hold the member 30 firmly in place. A small annular bead 34 having a diameter slightly less than the outer diameter of the member 30 is formed about the opening 26 as clearly seen in FIG. 2. To adapt the screwhead-engaging member 30 on a variety of screwhead sizes, an inwardly tapered cavity 36 extends from its outer end 38. Since the engaging member 30 is press fitted in the elongated structure 18, it is possible to use a number of engaging members with different shaped inward cavities with a stock elongated structure 18.

As clearly illustrated in FIGS. 1 and 6, the inner end 40 of the screwhead-engaging member 30 when inserted in the elongated structure 18 serves as a stop or retainer for a spring member 42. The other end of the spring 42 in the stretched condition of FIG. 1 is separated from an annular shoulder 44 by a clutch member 48. The clutch member 48 has a ring configuration 50 (see FIG. 4) whose outer diameter is slightly less than the diameter of circular bore 22 to permit it to slide freely along the bore 22. Extending inwardly from the ring structure 50 is a plurality of equally spaced resilient fingers 52. These fingers 52 are bent at an approximate 45.degree. angle to the ring portion 50. When the clutch member 48 is inserted in the structure 18, the fingers extend towards the rearward end 46 of the screwdriver attachment 10. With this arrangement, the fingers 52 frictionally engage the shank 14 of a screwdriver bit 16 with a much greater force when the shank 14 is inserted inwardly through the bore 22 as compared with the force applied on the shank 14 when the screwdriver 16 is pulled out of the attachment 10. This feature is significant for it permits the shank 14 to be easily removed from engagement with the attachment 10 but does not sacrifice the gripping force exerted by the fingers 15 required to hold the spring 42 under compression during the screwing operation, as illustrated in FIG. 5.

By using the above-described clutch member 48, it is possible to use the adapter 10 with screwdriver shanks having different cross-sectional shapes, such as round and hexagonal. All that is necessary is for the fingers 15 to exert a frictional gripping force on the shank 14 greater than the force exerted by the spring member 42 when under compression as shown in FIG. 5. The shank 14 can be readily shifted in position with respect to the elongated structure 18 by overcoming this frictional force when the shank 14 is inserted into the attachment 10. A very small pulling force on the shank 14 will remove it from the attachment 10 due to the fact that the gripping fingers 52 exert a very small frictional force on the shank 14 in the rearward direction.

In FIG. 6 is an illustration of the intended use for the screwdriver attachment 10. The lower opening 26 is placed over the head 60 of a screw 62 until the inner tapered surface 36 of the screwhead-engaging member 30 is seated firmly about the screwhead 60. Then when a thrust is applied on the bit 16, the shank 14 will advance against the spring 42 until the driving end 12 engages the screwhead 60 and the bit 16 is then rotated until it causes the driving end 12 to index within the slot or kerf 64 in the screwhead 60.

By reason of the foregoing construction of the screwhead finder 10, it can be seen that this invention discloses a screwdriver attachment which can be used interchangeably with shanks having different shapes and with shanks of the same shape but with different types of driving ends. Further, it is very economical to manufacture and can be made of most any desired material.

Claims

We claim:

1. An attachment for use with a screwdriver to guide and hold the driving end of its shank into engagement with the kerf of a screw comprising an elongated structure having a bore formed along its length and having an opening formed in its opposite ends, the internal surface extending inwardly from one of said ends being shaped to seat about the head of a screw and the opening in the other of said ends being sufficiently large to fit loosely about the shank of the screwdriver, a spring disposed in said bore extending between said opposite ends, and a clutch member having means for frictionally gripping the shank disposed between said spring and said other end, said clutch member having a ring configuration and said frictional engaging means comprising a plurality of resilient fingers extending from the inner surface of said ring configuration towards said other end of said elongated structure, where the frictional gripping force exerted by said gripping means against said shank is sufficient to compress said spring when said one end is seated about a screwhead and the driving end of the shank is pushed inwardly along said bore towards the screwhead but will slip upon the application of a substantially greater inward push on the shank.

2. An attachment for use with a screwdriver to guide and hold the driving end of its shank into engagement with the kerf of a screw comprising an elongated tubular structure having a bore formed along its length and having an opening formed in its opposite ends, a screwhead-engaging member mounted in the opening in one of said ends, said engaging member having a cavity which places the opening in said one end in communication with said bore and which is shaped to seat about the head of a screw, said cavity having an inwardly tapered shape and press fitted in said one end of said elongated structure the opening in said other end being sufficient in size to fit loosely about the screwdriver shank, a spring disposed in said bore extending between said other end of said structure and the inner end of said engaging member, and a clutch member having means for frictionally gripping the shank disposed between said other end and said spring, where the frictional gripping force exerted by said gripping means against said shank is sufficient to compress said spring when said one end is seated about a screwhead and the driving end of the shank is pushed along said bore towards the screwhead but will slip upon the application of a substantially greater inward push on the shank.

3. The combination of claim 2, wherein said clutch member has a ring configuration and said frictional engaging means comprises a plurality of resilient fingers extending from the inner surface of said ring configuration towards said other end of said elongated structure.

4. An attachment as defined in claim 2, wherein the inner end of said screwhead-engaging member abuts against a shoulder portion formed in said bore at a distance slightly greater than the length of said screwhead-engaging member, and wherein the outer end of said screwhead-engaging member abuts against a narrow resilient annual bead formed about said opening in said one end of said tubular structure.