Screw Driver Attachment

Abstract

A device for attachment to a power tool having a rotary output, such as a drill, which device includes a housing having an input member adapted to be connected to said tool output. The device has an output member with a screwdriver bit attached thereto. This output member is normally disengaged from the input member but is connected thereto and driven thereby when the bit is pressed against a work member.

Description

SUMMARY OF THE INVENTION

The present invention is directed to a unitary attachment which converts a powered mechanism having a straight rotary output to one whose output rotates only when pressed against a work member and which ceases to rotate when resistance torque thereon exceeds a predetermined level. The attachment is useful, particularly in converting the conventional drill to a screwdriver, embodies simplicity, reliability and durability, is compact and light in weight, and is relatively inexpensive to make.

Main objects of the present invention, therefore, are to provide an improved attachment for converting a powered mechanism having a straight rotary output, such as a drill, to one whose output includes a screwdriving bit and which rotates only when the bit is pressed axially against a work member and which slips (or ceases to rotate) when the torque resistance level (offered by the work member) exceeds a predetermined level.

Further important objects of the present invention are to provide an improved attachment of the above character which embodies utility, simplicity and durability, is relatively small, compact and lightweight, and is relatively inexpensive to manufacture and reliable in use.

Other objects and advantages of the present invention will become more apparent from a consideration of the detailed description to follow taken together with the drawings annexed hereto.

BROAD STATEMENT OF THE INVENTION

Broadly described, the present invention relates to a unitary attachment comprising input and output members telescopically engaged for slideable guiding support, a housing slideably and rotatably embracing said input and output members and retaining said members in telescopic engagement, said input member having a portion extending outwardly of said housing for removable attachment to said rotary output, cooperable clutch means formed on said input and output members and adapted to transmit rotation from said input member to said output member, means normally maintaining said clutch means disengaged but allowing cooperable engagement therebetween when axial force is applied to said output member, said clutch means being adapted to slip upon application of a predetermined level of torque resistance to said output member.

In another aspect, the present invention relates to a unitary attachment for a portable, powered device having a rotary output, said attachment comprising a housing, an input member slideably and rotatably disposed within said housing and having a portion extending outwardly thereof adapted to be secured to said rotary output, said attachment having an output member slideably and rotatably supported by said housing and having a portion closely slideably received in a bore in said input member, cooperable clutch means including a transverse pin fixed to said output member and receivable in cooperable grooves forged in said input member to transmit rotation from said input member to said output member, compression spring means in said bore and engaging said input and output members to normally maintain said clutch means disengaged but allowing cooperable engagement therebetween when axial force is applied to said output member, said clutch means being adapted to slip upon application of a predetermined level of torque resistance to said output member.

In still another aspect, the present invention relates to a unitary attachment for a portable, powered device having a rotary output, said attachment comprising a housing, an input member slideably and rotatably disposed within said housing and having a portion extending outwardly thereof adapted to be secured to said rotary output, said attachment having an output member slideably and rotatably supported by said housing, cooperable clutch means formed on said input and output members and adapted to transmit rotation from said input member to said output member, means normally maintaining said clutch means disengaged but allowing cooperable engagement therebetween when axial force is applied to said output member, said clutch means being adapted to slip upon application of a predetermined level of torque resistance to said output member, said housing including an in-turned flange defining a reduced opening through which said output member extends, said output member being restrained against axial movement outwardly of said housing by a transverse pin forming one part of said clutch means, said pin being disposed within said housing and adjacent said in-turned flange.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view, partly in section and partly in elevation, illustrating an attachment embodying the present invention;

FIG. 2 is a sectional view of FIG. 1 taken along the line 2- 2 thereof; and

FIG. 3 is a sectional view of FIG. 1 taken along the line 3- 3 thereof.

DETAILED DESCRIPTION

Referring now more specifically to the drawings, an attachment embodying the present invention is illustrated generally at 11 in FIG. 1 and is seen to include an annular housing 13. An input member or driver 15 is slidably and rotatably disposed in the housing 13 and is retained therein by a retaining ring 17. The driver 15 has a reduced shaftlike end 19 extending rearwardly of the housing 13 adapted to be connected to the rotary output of a portable, powered device. For example, the driver end 19 may be connected to a chuck 21 fixed to a spindle 23 of a portable drill 25 to impart rotary movement to the driver 15 from the drill 25.

The housing 13 has an inturned flange 27 at its forward end which defines a reduced opening 29. A generally cylindrical output member 31 extends through the opening 21 into the housing 13 and is slidably disposed within a bore 33 in the end of the driver 15. The output member 31 has a central bore 35 adapted to receive a screwdriver bit 37. The member 31 and the bit 37 are suitably keyed together for conjoint rotation, for example, the bore 35 and the bit 37 may have complementary hexagonal or otherwise noncircular cross-sectional configurations. If desired, detent ball means 38 may be provided in the output member 31 to releasably retain the screwdriver bit 37 in place therein. A split ring 53 on the member 31 holds the detent ball 38 in place.

The driver 15 and output member 31 are provided with engageable clutch means adapted to transmit rotation from said driver 15 to said output member 31. Thus, the driver 15 is provided with diametrically disposed sets of grooves 39, 41 and 43, 45 formed therein by forging and adapted to cooperatively receive a cylindrical pin 47 which extends transversely through and rotates with the output member 31. The clutch parts including the pin 47 and the sets of grooves 39, 41 and 43, 45 are normally separated by means of a compression spring 49 having one end seated in a pocket 51 in the bottom of the bore 33 and its other end received in the bore 35 in the output member 31 and bearing against the pin 47. The force of the spring 49 normally holds the driver 15 against the retaining ring 17 and the clutch pin 47 against the inturned flange 27; however, the driver 15 and output member 31 are selectively movable toward each other against the spring 49 to bring the pin 47 into cooperative clutching engagement with the grooves 39, 41 or the slots 43, 45 whereby to transmit rotation from the driver 15 to the output member 31.

As shown in FIG. 1, the output member 31 is supported by the housing 13 at the opening 29 and by the driver 15 at its bore 33. When the tool bit 37 is pressed against a work member, the driver 15 and output member 31 are caused to move relative to one another against the force of the spring 49 whereupon the pin 47 engages in the grooves 39, 41, or 43, 45 and causes the driver member 31 and the bit 37 to rotate with the driver 15. This direct drive continues until either the tool bit 37 is released from the work member or when the torque resistance on the tool bit 37 and the output member 31 reaches the slip level where the pin 47 cams out of its groove 39, 41 or 43, 45.

It will be appreciated that the attachment of the present invention may be used with a variety of powered devices of which portable electric drills are one example. This attachment embodies obvious simplicity, and its components, particularly the clutch parts, afford inexpensive manufacturing techniques. Thus, the pin 47 may be a bearing roller and the grooves 39, 41 and 43, 45 may be formed by a simple forging process as distinguished from the relatively expensive machining processes heretofore used in clutch components of this type.

While a preferred embodiment of the present invention has been illustrated and described above in detail, various additions, substitutions, modifications and omissions may be made thereto without departing from the spirit of the invention.

Claims

We claim:

1. A unitary attachment for a portable, powered device having a rotary output, said attachment comprising input and output members telescopically engaged for slideable guiding support, a housing slideably and rotatably embracing said input and output members and retaining said members in telescopic engagement, said input member having a portion extending outwardly of said housing for removable attachment to said rotary output, cooperable clutch means formed on said input and output members and adapted to transmit rotation from said input member to said output member, means normally maintaining said clutch means disengaged but allowing cooperable engagement therebetween when axial force is applied to said output member, said clutch means being adapted to slip upon application of a predetermined level of torque resistance to said output member.

2. An attachment as defined in claim 1 wherein said input member has a bore closely slidably receiving said output member.

3. An attachment as defined in claim 2 which includes compression spring means within said bore and engaging said input and output members to normally maintain said clutch means disengaged.

4. A unitary attachment for a portable, powered device having a rotary output, said attachment comprising a housing, an input member slideably and rotatably disposed within said housing and having a portion extending outwardly thereof adapted to be secured to said rotary output, said attachment having an output member slideably and rotatably supported by said housing and having a portion closely slideably received in a bore in said input member, cooperable clutch means including a transverse pin fixed to said output member and receivable in cooperable grooves forged in said input member to transmit rotation from said input member to said output member, compression spring means in said bore and engaging said input and output members to normally maintain said clutch means disengaged but allowing cooperable engagement therebetween when axial force is applied to said output member, said clutch means being adapted to slip upon application of a predetermined level of torque resistance to said output member.

5. A unitary attachment for a portable, powered device having a rotary output, said attachment comprising a housing, an input member slideably and rotatably disposed within said housing and having a portion extending outwardly thereof adapted to be secured to said rotary output, said attachment having an output member slideably and rotatably supported by said housing, cooperable clutch means formed on said input and output members and adapted to transmit rotation from said input member to said output member, means normally maintaining said clutch means disengaged but allowing cooperable engagement therebetween when axial force is applied to said output member, said clutch means being adapted to slip upon application of a predetermined level of torque resistance to said output member, said housing including an inturned flange defining a reduced opening through which said output member extends, said output member being restrained against axial movement outwardly of said housing by a transverse pin forming one part of said clutch means, said pin being disposed within said housing and adjacent said inturned flange.