Flexible extension shaft for a screwdriver

Abstract: A cordless portable electric screwdriver (10) having a chuck (12) for normally holding a tool (14) for rotary driven motion at one end (16) thereof. The screwdriver includes a flexible extension shaft (18) having a first end (20) adapted to cooperate with the chuck (12) and a second end (22) adapted to hold the tool (14) for rotary driven motion. The first end (20) of the flexible extension shaft (18) and the chuck (12) have complementarily shaped non-circular cross-sections. The chuck (12) has an axis and is adapted to receive the first end (20) of the flexible shaft (18) by means of axial insertion of the shaft (18) into the chuck (12) with the non-circular cross-sections in rotationally aligned relationship and the chuck (12) is also adapted to hold the first end (20) of the flexible extension shaft (18) for rotary driven motion of the shaft (18). The second end (22) of the flexible extension shaft (18) and the tool (14) have complementarily shaped non-­ circular cross-sections. The screwdriver (10) is operable to drive the tool (14) by reason of the second end (22) of the flexible shaft (18) holding the tool (14) for rotary driven motion thereof. With this arrangement, the flexible extension shaft (18) normally is disposed so as to be substantially entirely coaxial with the chuck (12) but is universally deflectable relative to the axis of the chuck (12) so as to position the second end (22) of the shaft (18) and the tool (14) at an acute angle relative thereto.

Description: This invention relates to a flexible extension shaft for a screwdriver. FR-A-2 533 985 discloses a flexible extension shaft for use with a cordless portable screwdriver having a chuck for normally holding a tool for rotary driven motion at one end thereof, the flexible extension shaft comprising a first end adapted to cooperate with said chuck and a second end adapted to hold said tool for rotary driven motion, said first end of said flexible extension shaft and said chuck having a first complementarily shaped non-circular cross-sections, said chuck having an axis and being adapted to receive said first end of said flexible extension shaft by means of axial insertion of said shaft into said chuck with said non-circular cross-sections in rotationally aligned relationship and said chuck also including means for holding said first end of said flexible extension shaft for rotary driven motion of said shaft, said second end of said shaft and said tool having second complementarily shaped non-circular cross-sections, said second end of said shaft including means for holding said tool for rotary driven motion thereof; said shaft normally being disposed so as to be substantially entirely coaxial with said chuck, said shaft being universally deflectable relative to said axis of said chuck so as to position said second end of said shaft and said tool at an acute angle relative to said axis of said chuck, said tool being rotary driven by said screwdriver through said shaft; said shaft (18) comprising a plurality of concentric coil springs in tightly wound adjacent relation extending between and secured to generally cylindrical body portions at said first and second ends of said shaft to accommodate universal deflection of said shaft relative to said axis of chuck, and a flexible sleeve disposed about said concentric coil springs, said flexible sleeve comprising a shoulder at each end, each shoulder forming a stop for a respective one of said cylindrical body portions, said cylindrical body portions being spaced apart by a distance greater than the distance between said shoulders to permit limited axial movement of said cylindrical body portions and said concentric coil springs relative to said shoulders and said flexible sleeve. Cordless portable electric screwdrivers have become very popular because they allow a workman to easily complete various tasks without manual effort or the hindrance of a power cord. In order to obtain optimum benefit, the workman has many tools for use with the cordless portable electric screwdriver including various types and sizes of drill bits, screwdriver tips and the like. Each tool must be fashioned to connect to a chuck which normally positions the tool in close proximity to the relatively large casing of the screwdriver. As a result, cordless portable electric screwdrivers have been rendered relatively ineffective for use in confined, difficult-to-reach locations. In this connection, cordless portable electric screwdrivers have generally been relatively long. As previously mentioned, they have also generally had a casing surrounding the motor which is quite large in relation to the tool, i.e., drill bits, screwdriver tips and the like. For this reason, it has been difficult to utilize a cordless portable electric screwdriver in areas of limited access. The present invention is directed to overcoming the above-stated problems and accomplishing the stated objects by providing a unique portable electric screwdriver having a flexible extension shaft. In accordance with the present invention there is provided a flexible extension shaft for use with a cordless hand-held portable electric screwdriver having a chuck for normally holding a tool for rotary driven motion at one end thereof, the flexible extension shaft comprising a first end adapted to cooperate with said chuck and a second end adapted to hold said tool for rotary driven motion, said first end of said flexible extension shaft and said chuck having a first complementarily shaped non-circular cross-sections, said chuck having an axis and being adapted to receive said first end of said flexible extension shaft by means of axial insertion of said shaft into said chuck with said non-circular cross-sections in rotationally aligned relationship and said chuck also including means for holding said first end of said flexible extension shaft for rotary driven motion of said shaft, said second end of said shaft and said tool having second complementarily shaped non-circular cross-sections, said second end of said shaft including means for holding said tool for rotary driven motion thereof; said shaft normally being disposed so as to be substantially entirely coaxial with said chuck, said shaft being universally deflectable relative to said axis of said chuck so as to position said second end of said shaft and said tool at an acute angle relative to said axis of said chuck, said tool being rotary driven by said screwdriver through said shaft; said shaft comprising a plurality of concentric coil springs in tightly wound adjacent relation extending between and secured to generally cylindrical body portions at said first and second ends of said shaft to accommodate universal deflection of said shaft relative to said axis of chuck, and a flexible sleeve disposed about said concentric coil springs, said flexible sleeve comprising a shoulder at each end, each shoulder forming a stop for a respective one of said cylindrical body portions, said cylindrical body portions being spaced apart by a distance greater than the distance between said shoulders to permit limited axial movement of said cylindrical body portions and said concentric coil springs relative to said shoulders and said flexible sleeve, and a shaft biasing coil spring disposed about said concentric coil springs of said shaft, said shaft biasing coil spring being disposed between one of said shoulders and the corresponding one of said cylindrical body portions to normally bias the other of said cylindrical body portions into engagement with said other shoulder whereby said flexible sleeve comprises cylindrical fittings secured thereto at opposite ends thereof, each cylindrical fitting defining a respective one of said shoulders therein internally of said fitting and slidably receiving substantially the whole of a respective one of said cylindrical body portions rotatably therein. As will be appreciated, the tool is rotary driven by the cordless portable electric screwdriver through the flexible extension shaft. For this purpose, the first and second ends of the flexible extension shaft include a generally cylindrical body portion, and preferably one body portion terminates in a male hex and the other cylindrical body portion terminates in a female hex shank-receiving opening. Between the first and second ends, the flexible extension shaft includes a plurality of concentric coil springs in tightly wound adjacent relation. The concentric coil springs are secured to the generally cylindrical body portions of the first and second ends of the flexible extension shaft to accommodate the universal deflection of the shaft relative to the axis of the chuck. A flexible sleeve is then disposed about the concentric coil springs. More specifically, the flexible sleeve preferably includes cylindrical fittings secured thereto at opposite ends thereof so as to define a shoulder internally of each of the fittings which are adapted to receive one of the cylindrical body portions therein. The cylindrical body portions are spaced apart by a distance greater than the distance between the shoulders in the cylindrical fittings to permit limited axial movement of the cylindrical body portions and the concentric coil springs relative to the cylindrical fittings and the flexible sleeve. A shaft biasing coil spring is then advantageously disposed about the concentric coil springs of the flexible sleeve. A shaft biasing coil spring is then advantageously disposed about the concentric coil springs of the flexible extension shaft. More specifically, the shaft biasing coil spring is disposed between the shoulder in one of the cylindrical fittings and the corresponding one of the cylindrical body portions to normally bias the other of the cylindrical body portions into engagement with the shoulder in the other of the cylindrical fittings. The invention will be described further hereinafter, by way of example only, with reference to, the accompanying drawings, in which:- Fig. 1 is a perspective view of a portable electric screwdriver having a flexible extension shaft in accordance with one embodiment of the present invention; Fig. 1A is a transverse cross-sectional view of the screwdriver and flexible extension shaft taken on the line 1A-1A of Fig. 1; Fig. 1B is a transverse cross-sectional view of the flexible extension shaft and a tool taken on the line 1B-1B of Fig. 1; Fig. 2 is a partial perspective view of the flexible extension shaft utilized in the screwdriver illustrated in Fig. 1; and Fig. 3 is a longitudinal cross-sectional view of the flexible extension shaft taken on the line 3-3 of Fig. 2. A cordless portable electric screwdriver 10 having a chuck 12 for normally holding a tool 14 for rotary driven motion at one end 16 thereof includes a flexible extension shaft 18 having a first end 20 adapted to cooperate with the chuck 12 and a second end 22 adapted to hold the tool 14 for rotary driven motion. The first end 20 of the shaft 18 and the chuck 12 have complementarily shaped non-circular cross-sections (see Fig. 1A). The chuck 12 has an axis 24 and is adapted to receive the first end 20 of the flexible extension shaft 18 by means of axial insertion of the shaft into the chuck with the non-circular cross-sections in rotationally aligned relationship and the chuck 12 also includes means for holding the first end 20 of the shaft 18 for rotary driven motion of the shaft. The second end 22 of the shaft 18 and the tool 14 also have complementarily shaped non-circular cross-sections (see Fig. 1B). The screwdriver 10 operates such that the second end 22 of he shaft 18 includes means for holding the tool 14 for rotary driven motion thereof. With this arrangement, the shaft 18 is normally disposed so as to be substantially entirely coaxial with the chuck 12 and is universally deflectable relative to the axis 24 of the chuck 12 so as to position the second end 22 of the shaft 18 and the tool 14 at an acute angle relative to the axis 24 of the chuck 12 (see in particular Fig. 1). Referring to Fig. 1 the tool 14 is rotary driven by the screwdriver 10 through the shaft 18. One of the first and second ends 20 of the shaft 18 includes a generally cylindrical body portion 20a terminating in a male hex shank 20b with the other of the first and second ends 22 including a generally cylindrical body portion 22a terminating in a female hex shank-receiving opening 22b. The chuck 12 includes a female hex shank-receiving opening 12a which, together with the male hex shank 20b, defines the first of the previously described complementarily shaped non-circular cross-sections and the tool 14 includes a male hex shank 14a which, together with the female hex shank-receiving opening 22b, defines the second of the previously described complementarily shaped non-circular cross-sections. With this arrangement, the first end 20 of the shaft 18 is adapted for insertion into the chuck 12 and the tool 14 is adapted for insertion into the second end 22 of the shaft 18. Referring to Figs. 1 and 2, the means for holding the tool 14 for rotary driven motion includes a detent 26 associated with the female hex shank-receiving opening 22b in the second end 22 of the shaft 18. In like fashion, the means for holding the first end 20 of the extension shaft 18 for rotary driven motion may include a plurality of fingers 28 associated with the female hex shank-receiving opening 12a in the chuck 12. Referring to Figs. 2 and 3, the shaft 18 includes a plurality of concentric coil springs 30,32,34 in tightly wound adjacent relation extending between and secured to the body portions 20a and 22a of the ends 20 and 22 of the shaft 18 to accommodate universal deflection of the shaft relative to the axis 24 of the chuck 12. A flexible sleeve 36 is disposed about the concentric coil springs 30,32,34 and has cylindrical fittings 38 and 40 secured thereto at opposite ends 42 and 44 thereof to receive one of the cylindrical body portions 20a and 22a therein and the flexible sleeve 36 and cylindrical fittings 38 and 40 define shoulders 46 and 48 internally of each of the fittings 38 and 40 to form stops for the cylindrical body portions 20a and 22a. More specifically, the cylindrical body portions 20a and 22a are spaced apart by a distance greater than the distance between the shoulders 46 and 48 in the cylindrical fittings 38 and 40 to permit limited axial movement of the cylindrical body portions 20a and 22a and the concentric coil springs 30,32,34 relative to the cylindrical fittings 38 and 40 and the sleeve 36. With this construction, a shaft biasing coil spring 50 is disposed about the concentric coil springs 30,32,34 of the shaft 18 between the shoulder 46 in one of the cylindrical fittings 38 in the corresponding one of the cylindrical body portions 20a to normally bias the other of the cylindrical body portions 22a into engagement with the shoulder 48 in the other of the cylindrical fittings 40. The cordless portable electric screwdriver 10 when utilized with the unique flexible extension shaft 18 is extremely versatile. The fact that it is universally deflectable relative to the axis 24 of the chuck 12 accommodates use of the screwdriver 10 in hard-to-reach or limited access areas since the tool 14 can be disposed at an acute angle relative to the axis 24 of the chuck 12 by deflecting or bending the flexible extension shaft 18 such as illustrated in Fig. 1. In this connection, the flexible sleeve 36 permits the user to grip the flexible extension shaft 18 in one hand to hold it in a deflected position during use without exposure to the moving parts. In a known manner, the other hand would hold the screwdriver 10. In other words, the concentric coil springs 30,32,34 are rotating internally of the flexible sleeve 36 and the difference in distance between the cylindrical body portions 20a and 22a and the cylindrical fittings 38 and 40 accommodate the arc into which the flexible extension shaft is oftentimes advantageously deflected and held during use of the screwdriver.

Claims: A flexible extension shaft for use with a cordless hand-held portable electric screwdriver having a chuck for normally holding a tool for rotary driven motion at one end thereof, the flexible extension shaft (18) comprising a first end (20) adapted to cooperate with said chuck (12) and a second end (22) adapted to hold said tool (14) for rotary driven motion, said first end (20) of said flexible extension shaft (18) and said chuck (12) having a first complementarily shaped non-circular cross-sections, said chuck (12) having an axis (24) and being adapted to receive said first end (20) of said flexible extension shaft (18) by means of axial insertion of said shaft (18) into said chuck (12) with said non-circular cross-sections in rotationally aligned relationship and said chuck (12) also including means for holding said first end (20) of said flexible extension shaft (18) for rotary driven motion of said shaft (18), said second end (22) of said shaft (18) and said tool (14) having second complementarily shaped non-circular cross-sections, said second end (22) of said shaft (18) including means for holding said tool (14) for rotary driven motion thereof; said shaft (18) normally being disposed so as to be substantially entirely coaxial with said chuck (12), said shaft (18) being universally deflectable relative to said axis (24) of said chuck (12) so as to position said second end (22) of said shaft (18) and said tool (14) at an acute angle relative to said axis (24) of said chuck (12), said tool (14) being rotary driven by said screwdriver (10) through said shaft (18); said shaft (18) comprising a plurality of concentric coil springs (30, 32, 34) in tightly wound adjacent relation extending between and secured to generally cylindrical body portions (20a, 22a) at said first and second ends (20, 22) of said shaft (18) to accommodate universal deflection of said shaft (18) relative to said axis (24) of chuck (12), and a flexible sleeve (36) disposed about said concentric coil springs (30, 32, 34), said flexible sleeve (36) comprising a shoulder (46, 48) at each end, each shoulder forming a stop for a respective one of said cylindrical body portions (20a, 22a), said cylindrical body portions (20a, 22a) being spaced apart by a distance greater than the distance between said shoulders (46, 48) to permit limited axial movement of said cylindrical body portions (20a, 22a) and said concentric coil springs (30, 32, 34) relative to said shoulders and said flexible sleeve (36), and a shaft biasing coil spring (50) disposed about said concentric coil springs (30,32,34) of said shaft (18), said shaft biasing coil spring (50) being disposed between one of said shoulders (46,48) and the corresponding one of said cylindrical body portions (20a,22a) to normally bias the other of said cylindrical body portions (20a,22a) into engagement with said other shoulder (46,48) whereby said flexible sleeve (36) comprises cylindrical fittings (38,40) secured thereto at opposite ends (42,44) thereof, each cylindrical fitting defining a respective one of said shoulders (46,48) therein internally of said fitting (38,40) and slidably receiving substantially the whole of a respective one of said cylindrical body portions (20a,22a) rotatably therein. A flexible extension shaft as claimed in claim 1, wherein said first end (20) of said shaft (18) or said chuck (12) includes a male hex shank (20b) and said chuck (12) or said first end (20) includes a female hex shank-receiving opening (12a) defining the first of said complementarily shaped non-circular cross-sections. A flexible extension shaft as claimed in claim 2, in combination with a cordless portable electric screwdriver (10), wherein said means of the screwdriver (10) for holding said first end (20) of said shaft (18) for rotary driven motion of said shaft (18) includes a plurality of fingers (28) associated with said chuck (12). A flexible extension shaft as claimed in claim 1 or 2 wherein said second end (22) of said shaft (18) or said tool (14) includes a female hex shank-receiving opening (22b) for engaging the tool (14) or said end (22) which includes a male hex shank (14a), defining the second of said complementarily shaped non-circular cross-sections. A flexible extension shaft as claimed in claim 4, wherein one of said first and second ends of said flexible extension shaft includes a generally cylindrical body portion terminating in a male hex shank and the other of said first and second ends of said flexible extension shaft includes a generally cylindrical body portion terminating in a female hex shank-receiving opening. A flexible extension shaft as claimed in claim 4 wherein said means for holding said tool (14) for rotary driven motion includes a detent (26) associated with said female hex shank-receiving opening (22b) in said second end (22) of said shaft (18). A flexible extension shaft as claimed in claims 1 or 3, in combination with a cordless portable electric screwdriver (10) having a chuck (12) for normally holding a tool (14) for rotary driven motion at one end thereof and a non-circular cross-section complementary to the first end of said shaft. A flexible extension shaft as claimed in claims 1 or 3, in combination with a cordless portable electric screwdriver (10) and a tool (14), the screwdriver (10) having a chuck (12) for normally holding a tool (14) for rotary driven motion at one end thereof and a non-circular cross-section complementary to the first end (20) of the shaft (18), and the tool (14) having a non-circular cross-section complementary to the second end (22) of the shaft (18).

Inventors: KOZAK BURTON, KOZAK, BURTON
Applicants: KOZAK BURTON, KOZAK, BURTON
Application year: 1989
Main classification: B25B13
IPC codes: B25G1, B25B13, B25B23, B25B15, B25B21