Background Art Screwdrivers are widely used in construction, in the assembly sites of machines and furniture, and in the home.

The most common types of screwdrivers are straight-line screwdrivers and Philips screwdrivers which are shaped to fit the grooved heads of the most common kinds of screws. Combined-use screwdrivers or replaceable screwdrivers are also widespread.

Combined-use screwdrivers or replaceable screwdrivers have different tips such as a straight-line and a Philips tip which are selectively inserted into and combined with the body of a screwdriver. In the past, most screwdrivers were nonmagnetic, but magnetic screwdrivers, whose ends which contact the screws are magnetized to hold on to loose, have been developed and are currently widespread because of their convenience.

Magnets are installed at the bodies of magnetic screwdrivers so that magnetism is formed at the ends of the screwdrivers. Also, nonmagnetic screwdrivers which have tips for covering screw heads so that the screws are easily unscrewed have developed and used.

However, conventional screwdrivers have removable or non-removable magnets or tips for covering screw heads. Since conventional screwdrivers depend on an induced magnetic force which is

weak, screws are easily separated from the screwdrivers. Also, conventional screwdrivers can only used for predetermined standardized screws. Thus, screws having too deep or too shallow heads may not fit with conventional screwdrivers.

Also, if a screwing operation is performed in a narrow slit or an opening using a conventional screwdriver having a magnet or a tip in one body or in an attached way, the use of the conventional screwdriver is complicated or impossible because of the volume of the magnet or the tip.

Also, since the conventional screwdrivers do not have a moveable magnet, screws are weakly bound to or misaligned with the screwdriver tip. Thus, screws may fall down, may be screwed in crookedly, and if an excessive force is applied to the screws or excessive rotary power is applied to the screws which are already completely screwed in, the screws or objects are damaged.

Disclosure of the Invention To solve the above-described problems, it is a first object of the present invention to provide a screw guider of a screwdriver which is attachable to and detachable from existing screwdrivers so as to be applicable to various standardized screwdrivers, and in which a moveable sleeve is automatically or manually retracted to enable a screwing operation to be performed in a narrow slit or an opening.

It is a second object of the present invention to provide a screw guider of a screwdriver in which a magnet freely moves within a predetermined space, using a multi-iron effect to move the magnet in a direction of a large amount of iron, so that when a tip of the screwdriver engages a screw, the magnet moves forward and closely contacts the screw head, regardless of the size or shape of the screw head, so that the screw does not fall

It is a third object of the present invention to provide a screw guider of a screwdriver in which a magnet is built into a moveable sleeve and the moveable sleeve supports a screw or the moveable sleeve with the built-in magnet is supported by a fixed sleeve to support the screw and prevent the screw from being screwed into an object beyond a predetermined depth to prevent the object from being damaged.

It is a fourth object of the present invention to provide a screw guider of a screwdriver in which rotary power of the screwdriver is automatically interrupted to prevent the screw, the screwdriver, or the object from being damaged if there is an excessive resistance to turning the screw or if the screw is inserted into an object beyond a predetermined depth.

Accordingly, to achieve the above objects, there is provided a screw guider of a screwdriver, which is attachable to and detachable from a screwdriver. The screw guider includes a fixed sleeve, a moveable sleeve, a position fixing means, and a spring. The fixed sleeve is attachable to and detachable from the screwdriver. The moveable sleeve moves forward and backward with respect to the fixed sleeve and has a front end which contacts a screw head to support the screw head.

The position fixing means selectively fixes advancing and retracting positions of the moveable sleeve. The spring is installed between the fixed sleeve and the moveable sleeve for biasing the moveable sleeve in a predetermined direction.

Preferably, a magnet or a magnetized screw head support is attachable to and detachable from or fixed on the front end of the moveable sleeve and the moveable sleeve is freely advanced and retracted without receiving force from the spring, or the magnet or the magnetized screw head support is freely advanced and retracted so that the magnet or the magnetized screw head support is generally attached

to the screwdriver by a magnetic force using a multi-iron effect for moving the magnet in a direction of a large amount of iron but moves toward and is attached to a screw if the screw approaches the front end of the screwdriver.

Preferably, the position fixing means is a protrusion formed outside or inside the fixed sleeve and a guiding groove, for guiding the protrusion, formed outside or inside the moveable sleeve, or a groove formed on the screwdriver and balls formed on the moveable sleeve. The position fixing means may be a guiding groove which is formed inside the fixed sleeve to guide a protrusion formed outside the moveable sleeve.

A rotating clutch may be further formed to interrupt the transmission of rotary power between a screwdriver tip and a screwdriver shank so that the rotary power of the screwdriver is not transmitted to the screw if the screw receives excessive force or is inserted beyond a predetermined depth. The rotating clutch may transmit rotary power between the screwdriver tip and the screwdriver shank when the screw receives a predetermined force.

Brief Description of the Drawings FIG. 1 is a cross-sectional view of a screw guider of a screwdriver according to a first preferred embodiment of the present invention; FIG. 2 is a cross-sectional view of a screw guider of a screwdriver according to a second preferred embodiment of the present invention; FIG. 3 is a cross-sectional view of an embodiment of a magnet shown in FIG. 1; FIG. 4 a cross-sectional view of another embodiment of the magnet shown in FIG. 1; FIGS. 5 and 6 are cross-sectional views of a screw guider of a screwdriver according to third and fourth preferred embodiments of the

present invention; FIG. 7 is a cross-sectional view of a magnet shown in FIGS. 5 and 6 ; FIGS. 8,9A, and 9B are cross-sectional views showing grooves -and balls according to the present invention; FIGS. 10 and 11 are cross-section views of a screw guider of a screwdriver according to fifth and sixth preferred embodiments of the present invention ; FIGS. 12 through 20 are cross-sectional views of a rotating clutch according to the present invention; FIG. 21 is a cross-sectional view of a guiding groove according to the present invention; FIGS. 22 through 25 are cross-sectional views of examples of a guidinggroove ; FIG. 26 is a perspective view of friction members of a rotating clutch according to the present invention ; FIG. 27 is a perspective view of a magnet according to the present invention ; FIGS. 28 and 29 are cross-sectional views of a screw guider of a screwdriver according to seventh and eighth preferred embodiments of the present invention; FIGS. 30 and 31 are cross-sectional views of magnets shown in FIGS. 28 and 29, respectively; FIG. 32 is a perspective view of a screw fixture according to the present invention; and FIGS. 33 through 35 are cross-sectional views of a screw guider of a screwdriver according to ninth and tenth preferred embodiments of the present invention.

Best mode for carrying out the Invention Hereinafter, a screw guider of a screwdriver according to preferred embodiments of the present invention will be described with reference to the attached drawings.

As shown in FIG. 1, a screw guider of a screwdriver according to a preferred embodiment of the present invention, which is attachable to and detachable from a screwdriver, includes a fixed sleeve 10, a moveable sleeve 20, a position fixing means, and a spring 30.

The fixed sleeve 10 is attachable to and detachable from a screwdriver 2. The fixed sleeve 10, into which the screwdriver 2 is inserted, is fixed on the screwdriver 2 by a screw clamp 32 formed at the back end of the fixed sleeve 10. Accordingly, the screw clamp 32 is unscrewed to untighten the fixed sleeve 10 from the screwdriver 2. Thus, the screw guider of the present invention is attachable to and detachable from various existing screwdrivers.

Here, instead of the screw clamp 32, a ring clamp may be used.

Also, as shown FIGS. 2,5, and 11, grooves 2a may be formed at the screwdriver 2 and balls 26 having a shape opposite to the grooves 2a may be formed to forcibly engage the fixed sleeve 10 with the screwdriver 2.

As shown in FIG. 32, a male screw is formed on the outside of the fixed sleeve 10 and rectangular grooves are formed in the fixed sleeve 10 to be screwed with the screw clamp 32. Then, the screw clamp 32 is tightened to fix the fixed sleeve 10. on the screwdriver 2. Alternatively, circular grooves are formed in the male screw and balls 26 are inserted into the circular grooves to be joined with the screw clamp 32. Either one or both of these two ways may be used.

These fixing means may have various shapes and may be changed and modified by one of ordinary skill in the art.

The moveable sleeve 20 may be advanced and retracted with respect to the fixed sleeve 10. The front end of the moveable sleeve 20 contacts a screw 1 to support the screw 1. The moveable sleeve 20 may include an additional screw head support having a concave screw groove to support the screw 1. However, it is preferable that the moveable sleeve 20 steadies the screw head using a strong magnetic force of a magnet. The additional screw head support may have a square or ellipsoid shape. A magnet 40 may be fixed on the front end of the moveable sleeve 20.

Here, the magnet 40 sticks to the screw 1 by using a multi-iron effect for moving a magnet to a direction of a large amount of iron.

However, the moveable sleeve 20 may not receive a force from the spring 30 and freely move forward and backward within a predetermined distance so that the magnet 40 moves to and sticks to the screw 1 if the screw 1 approaches the tip of the screwdriver 2.

As shown in FIGS. 3,4, and 6, the magnet 40 and the screw head support may be freely advanced and retracted at regular intervals although the moveable sleeve 20 is not advanced and retracted.

In other words, the cylindrical magnet 40, through which the screwdriver 20 penetrates, is formed at the front end of the moveable sleeve 20 and is advanced and retracted. A magnet external sleeve 42 is formed to wrap around the magnet 40 so that the magnet 40 does not spring out.

As shown in FIG. 7, the magnet external sleeve 42 may be engaged with a groove 2c bored in the screwdriver 2 so that the magnet external sleeve 42 is advanced and retracted.

Here, the magnet 40 may have various shapes such as a cylindrical shape and a ring shape. If the screwdriver 2 is very small, the magnet 40 may be formed of a plurality of cylindrical magnets 94 which

may be inserted into holes of a magnet fixing body 92 as shown in FIG.

27.

Accordingly, if the screw 1 approaches the tip of the screwdriver 2, the magnet 40, which is retracted toward the screwdriver 2, moves to the screw 1 containing a large amount of iron component due to a multi-iron effect. Thus, the magnet 40 contacts the screw 1 due to magnetic force and thus the screw 1 is strongly combined with the screwdriver 2 by magnetic or mechanical force. As a result, the screw 1 is prevented from falling.

The position fixing means selectively fixes advancing and retracting positions of the moveable sleeve 20 with respect to the fixed sleeve 10. The position fixing means includes a protrusion 50 and a guiding groove 52. The protrusion 50 is formed outside the fixed sleeve 10 and the guiding groove 52 for guiding the protrusion 50 is formed inside the moveable sleeve 20.

As shown in FIG. 21, the guiding groove 52 is composed of a longitudinal groove 20a and a lateral groove 20b. The longitudinal groove 20a is longitudinal to guide advancing and retracting movements of the moveable sleeve 20. The lateral groove 20b is formed at one end of the longitudinal groove 20a to fix the advancing or retracting position of the moveable sleeve 20. Although not shown in FIG. 21, in some cases, two lateral grooves 20b are formed at both ends of the longitudinal groove 20a to fix both the advancing and retracting positions of the moveable sleeve 20. A short longitudinal groove 20c may extend from the lateral groove 20b so that the magnet 40 fixed on the moveable sleeve 20 is advanced and retracted within a predetermined distance.

The spring 30 shown in the FIG. 1 is installed between the fixed sleeve 10 and the moveable sleeve 20 so that a restoring force of the spring 30 is applied to the moveable sleeve 20.

Accordingly, if a user advances the moveable sleeve 20 to fix the screw 1 on the magnet 40, the protrusion 50 is guided toward the lateral groove 20b at the back of the longitudinal groove 20a and rotated and retracted in the short longitudinal groove 20c extending from the lateral groove 20b by a predetermined length due to a multi-iron effect. If use of the magnet 40 unnecessary or a screwing operation is performed in a narrow space, the moveable sleeve 20 is retracted and the protrusion 50 is guided toward the lateral groove 20b at the front of the longitudinal groove 20a so that the retracting position of the protrusion 50 is fixed.

Here, the protrusion 50 is not moved by pressure applied from the spring 30.

The guiding groove 52 may be formed inside the moveable sleeve 20, or may be formed at an additional internal sleeve 22 for manufacturing convenience.

Various embodiments of the guiding groove 52 are shown in FIGS.

22 through 25. In other words, as shown in FIG. 22, the guiding groove 52 may be composed of the short longitudinal groove 20c and the lateral groove 20b. As shown in FIG. 23, the guiding groove 52 may be composed of the longitudinal groove 20a and the lateral grooves 20b formed in one direction at both ends of the longitudinal groove 20a. As shown in FIG. 24, the guiding groove 52 may be composed of the longitudinal groove 20a, the short longitudinal groove 20c and the lateral groove 20b formed at one end of the longitudinal groove 20a, and the lateral groove 20b formed in one direction at the other end of the longitudinal groove 20a. As shown in FIG. 25, the guiding groove 52 may be composed of the longitudinal groove 20a and the lateral grooves 20b formed at both ends of the longitudinal groove 20a in opposite directions.

Thus, the moveable sleeve 20 may move forward and backward

along the longitudinal groove 20a, be safely fixed in the lateral groove 20b, and be advanced and retracted a predetermined distance in the short longitudinal groove 20c.

Instead of the protrusion 50 and the guiding groove 52, as shown in FIGS. 8,9A, and 9B, a groove 2a formed at the screwdriver 20, a groove 2c for a multi-iron effect, and balls 26 formed at the moveable sleeve 20 may be used as the position fixing means so that the advancing and retracting positions of the moveable sleeve 20 are fixed.

If the user does not need the multi-iron effect, the user applies a predetermined force to the moveable sleeve 20. Then, the moveable sleeve 20 moves, is engaged with the groove 2a, and is fixed as shown in FIG. 9B.

The position fixing means for fixing the advancing and retracting positions of the moveable sleeve 20 may have various shapes and may be changed and modified by one of ordinary skill in the art.

As shown in FIG. 10, a screwdriver tip 64, which is attachable to and detachable from a screwdriver shank 62, is additionally manufactured.

Thus, the screwdriver tip 64 may be changed to match various different screw heads.

Here, a guide member 401 for supporting the magnet 40 is manufactured to have a smaller size than the inside diameter of the magnet 40. Thus, the magnet 40 is prevented from sticking to the screwdriver tip 64 so that the moveable sleeve 20 can move freely.

The screwdriver shank 62 may have an end 2k as shown in FIGS.

33 through 35 so as to be attachable to and detachable from the screwdriver 2.

FIGS. 12 through 20 show various embodiments of a rotating clutch 60 which may be formed in the screw guider of the screwdriver according to the present invention. The rotating clutch 60 interrupts the

transmission of a rotary power between the screwdriver tip 64 and the screwdriver shank 62 so that the rotary power of the screwdriver 2 is not transmitted to the screw 1 if there is excessive resistance to the turning of the screw 1 or if the screw 1 is screwed into an object to a predetermined depth. The rotating clutch 60 includes the screwdriver shank 62, the screwdriver tip 64, a pair of friction members 66, and a clutch spring 68.

The screwdriver shank 62 is coupled to a screwdriver handle. The screwdriver tip 64 is spaced apart from the screwdriver shank 64 and moveable forward and backward depending on a force applied to the screw 1. The friction members 66 are installed on the screwdriver shank 62 and the screwdriver tip 64, are opposite to each other, and contact each other depending on the advancing and retracting of the screwdriver tip 64. The clutch spring 68 has a restoring force which biases the friction members 66 apart or together.

Referring to FIG. 14, a force originating at the screwdriver tip 64, which pressed into a screw head, exceeds the restoring force of the clutch spring 68. Also, the friction members 66 are spaced apart from each other by the force originating from the screwdriver tip 64. Thus, the rotating clutch 60 interrupts the transmission of rotary power from screwdriver shank 62 to the screwdriver tip 64, preventing the screw 1 from receiving excessive force.

An extension sleeve 70 which contacts an object is formed on the screwdriver tip 64. If the extension sleeve 70 is pushed against the object, the extension sleeve 70 moves backward to indirectly push one of the friction members 66 of the rotating clutch 60. Thus, a rotary force is interrupted. As a result, the screw 1 can only be screwed into an object to a predetermined depth.

The friction members 66, the groove 2a formed on one of the friction members 66, the balls 26, and a ball support 67 for supporting the

balls 26 are shown in FIG. 26. Here, the groove 2a is formed around the circumference of one side of one of the friction members 66. The groove 2a prevents the moveable sleeve 20 from advancing and retracting but allows it to freely rotate when the balls 26 are fit into the groove 2a. The groove 2a may have various shapes. It is not shown, but if the groove 2a is a plurality of hemispherical grooves, which are spaced apart from each other around the circumference of one of the friction members 66, the hemispherical grooves hold the advancing and retracting movements as well as the rotation of the moveable sleeve 20.

In FIG. 12, if a predetermined force is applied to the screw 1, the rotary power of the rotating clutch 60 is applied to the screw 1 to rotate the screw 1.

In FIG. 13, if a predetermined force is applied to the screw 1, the rotary power is interrupted by disengagement of the rotating clutch.

Here, a clutch pressuring means for connecting the rotating clutch may have various shapes. As shown in FIG. 15, the friction members 66 may be pressured by the clutch spring 68. As shown in FIG. 16, the friction members 66 may be pressured by the magnetic force of the magnet 40. As shown in FIG. 17, the friction members 66 may be pressured by the plurality of hemispheric grooves 2a and balls 26. Thus, it is possible to perform a complex rotating clutch operation for transmitting or interrupting the transmission of rotary power.

The clutch pressuring means may by constituted so as to control a restoring force of the clutch spring and the depth of the screwdriver tip.

An insulating sleeve may be additionally installed outside the screwdriver 2, or the most external sleeve may be formed of an insulating material. Thus, an insulating screwdriver may be used.

As shown in FIGS. 18 through 20, the rotating clutch 60 controls the transfer of power to the screwdriver tip by advancing and retracting

the screwdriver tip using the grooves 2a and balls 26.

As shown in FIGS. 28 and 29, the screw guider may not include a spring.

As shown in FIGS. 33 through 35, grooves are formed at both ends of the screwdriver tip 64. Balls 26, which have a shape opposite to the grooves of the screwdriver tip 64, are formed at the fixed sleeve 10. Thus, the screwdriver tip 64 is replaceable and extensions with tips at both ends can be inserted forwards or backwards enabling either tip to be used.

The above-described embodiments of the present invention can be modified into various other forms, and the scope of the present invention must not be interpreted as being restricted to the described embodiments.

It will be apparent to one of ordinary skill in the art that various modifications to the described embodiments may be made without departing from the spirit and scope of the invention.

For example, the above-described embodiments of the present invention relate to a screw guider of a screwdriver, but the present invention may also be applied to spanners, wrenches, or drill chucks.

Accordingly, the true technical protective scope of the present invention must not be limited to the scope of the detailed description, but rather determined based on the technical spirit of the appended claims.

Industrial Applicability As described above, a screw guider of a screwdriver according to the present invention is attachable to and detachable from various existing screwdrivers. Advancing and retracting positions of the screw guider may be selectively determined. Thus, the screw guider has various functions. A moveable sleeve can be completely retracted, allowing a screwdriver of the present invention to be used as an existing

screwdriver and in narrow spaces. No matter whether the head of a screw is deep or shallow, or whether the screw is large or small, the screw is automatically and completely joined with the screwdriver by magnetic and mechanical force so that the screw does not fall. A user can perform a screwing operation with one hand without holding the screw.