Source: http://www.google.com/patents/US4884478?ie=ISO-8859-1
Timestamp: 2014-10-02 16:52:13
Document Index: 153540166

Matched Legal Cases: ['art. 3', 'art. 7', 'art. 8', 'art. 12', 'art 3', 'art 3', 'art 3', 'art 8', 'art 3', 'art 8', 'art 8', 'art 3', 'art 8', 'art 8', 'art 8', 'art 9', 'art 8', 'art 8']

Patent US4884478 - Screw tool - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsA screw tool has a direction-reversible catch including clamping members disposed within wedge-shaped clamping spaces between an outer drive ring part (5) and an inner driven core part (8) of approximately triangular shape in cross section, the clamping members are displaceable by a rotatable switch...http://www.google.com/patents/US4884478?utm_source=gb-gplus-sharePatent US4884478 - Screw toolAdvanced Patent SearchPublication numberUS4884478 APublication typeGrantApplication numberUS 07/098,374Publication dateDec 5, 1989Filing dateSep 17, 1987Priority dateOct 31, 1985Fee statusPaidPublication number07098374, 098374, US 4884478 A, US 4884478A, US-A-4884478, US4884478 A, US4884478AInventorsKarl LieserOriginal AssigneeWera Werk Hermann Werner Gmbh & Co.Export CitationBiBTeX, EndNote, RefManPatent Citations (10), Referenced by (12), Classifications (8), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetScrew toolUS 4884478 AAbstract A screw tool has a direction-reversible catch including clamping members disposed within wedge-shaped clamping spaces between an outer drive ring part (5) and an inner driven core part (8) of approximately triangular shape in cross section, the clamping members are displaceable by a rotatable switch member which is lockable in its switch positions into release with respect to the wedge walls of the corresponding clamping space by drivers acting on the clamping members and blocking the passage of the clamping members into, in each case one of their two clamping positions, and it proposes, in provide for a structurally simple friction-minimized construction wherein each clamping member lies loosely in a clamping space and is displaceable into its clamping position by the rotation of the drive ring part.
I claim: 1. In a screw tool with direction-reversible catch, the tool comprising an outer drive ring part, and an inner driven core part of approximately triangular cross section;a rotatable switch member having a plurality of drivers extending therefrom and arranged circumferentially around said core part; clamping members in wedge-shaped clamping spaces between said outer drive ring part and said inner driven core part, which clamping members are displaceable by said rotatable switch member which is lockable in its switch positions, each of said wedge-shaped clamping spaces having two clamping positions at opposite ends of a clamping space for receiving and clamping one of the clamping members; and wherein said drivers act on the clamping members and block passage of the clamping members into respectively one of their two clamping positions and wherein; in two switch positions of the switch member, each of said clamping members is loosely disposed in a separate of said clamping spaces and is displaceable into a clamping position therein exclusively by rotation of the drive ring part; in a central switch position of said switch member, each of said clamping bodies is located substantially centrally to a corresponding side of said driven core part; vertices of said core part are arranged concentrically about said core part to separate said clamping spaces, said drivers being located at respective ones of said vertices and being translatable in circumferential direction relative to said vertices upon rotation of said switch member about said core part; and said drivers extend in circumferential direction into said clamping spaces to limit movement of said clamping members in said clamping spaces to a predetermined region of unobstructed movement, a circumferentiakl length of said predetermined region of unobstructed movement being approximately equal to a circumferential length of a driver. 2. A screw tool according to claim 1, whereinsaid driven core part has said sides formed with barreled shape with a smaller degree of curvature than that of said drive ring part. 3. A screw tool according to claim 1, whereinsaid driven core part carries a spring-loaded detent ball on one of its angle bisectors in a blind bore, detent depressions opposite said ball, said detent depressions being formed on an inner wall of said switch member, the latter having said drivers in the form of axially protruding fingers, said switch member being cup-shaped. 4. A screw tool according to claim 3, whereinsaid driven core part forms concentrically extending guide surfaces disposed transverse to said angle bisectors and which rest against said cup inner wall. 5. A screw tool according to claim 3, whereinsaid driven core part has a central guide collar adapted to enter into a bore within a cup bottom of said switch member. 6. A screw tool according to claim 5, whereinsaid driven core part has, opposite the guide collar, a guide sleeve which protrudes into a screwdriver handle inner member, said sleeve having a wall surface provided with bearing ribs bearing against said inner member, and said inner member is one-piece with said drive ring part. 7. A screw tool according to claim 1, whereinsaid clamping members are shaped as rollers and rest only with a part of one of their end surfaces on bottom surfaces formed in the region of said clamping spaces by protrusions of said driven core part. 8. A screw tool according to claim 7, whereinouter edges of the bottom surfaces and guide surfaces of said driven core part supplement each other to form a circle. 9. A screw tool according to claim 7, whereinsaid drivers extend to the bottom surfaces and said clamping members have axial lengths corresponding to that of the drivers so that another end surface of the clamping members is gripped by a cup rim surface of said switch member, said switch member being cup-shaped. 10. A screw tool according to claim 3, whereinsaid detent depressions provide three switch positions and comprise a central one of said detent depressions corresponding to said central switch position which is operative in both directions of rotation and has a shape complementary to said detent ball, and two of said detent depressions directly adjacent said central detent depression which are each enlarged in shape in the directions of rotation and each provided with a concave bottom. 11. A screw tool according to claim 1, whereinsaid switch member in said switch positions is lockable in different relative positions to said driven core part. 12. A screw tool according to claim 11, whereinsaid drive ring part and said driven core part are relatively rotatably mounted. 13. A screw tool according to claim 1, whereinin said central switch position said drivers are adjacent lateral ends of said sides of said driven core part and spaced apart from said clamping members. 14. A screw tool according to claim 1, whereinin said two switch positions of said switch member said drivers are adjacent said clamping members. 15. A screw tool according to claim 8, whereinsaid guide surfaces of said driven core part relatively rotatably engage on an inner wall of said switch member. Description
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The screw tool developed as a screwdriver in accordance with the first embodiment shown in FIGS. 1 to 5 has a screwdriver handle 1 which is provided with an axially arranged inner member 2. The latter is seated, non-rotatably, in the screwdriver handle 1 and at its lower end forms a drive ring part 3 of larger cross section; see FIG. 1. In the free end of the drive ring part 3 there are produced stepped bore sections 4, 5, 6 in such a manner that the bore sections 4, 5 lie along the height of the drive ring part 3. The bore section 6 of smaller cross section which extends within the inner member 2 receives for rotation a bearing sleeve 7 which is equipped with rotating bearing ribs 7', 7", said sleeve being integral with a driven core part 8 arranged within the drive ring part 3. The driven core part 8 which is of triangular cross section has barrel-shaped triangle sides 9. Their degree of curvature is less than that of the wall of the bore section 5. The driven core part 8 forms guide surfaces 9' which are concentric to the bore section 5 and transverse to the angle bisectors, said guide surfaces connecting the triangle sides 9 to each other. The barreled triangle sides 9 are formed by polygonal turning, as a result of which protrusions 10 which rest on the bottom of the bore section 5 are formed. Their outer edges 10' and the guide surfaces 9' supplement each other to form a circle; see in particular FIGS. 2 and 4.
On the other side of the free front end of the drive ring part 3, the driven core part 8 continues in a stepwise guide collar 11. Adjoining the latter there is a stepwise stepped-down extension 11'. The latter serves to receive a clamping spring 12 indicated in dash-dot line, for the frictional holding of a screwdriver insert part of hexagonal cross section. For the reception thereof a hexagonal opening 13 is provided in the driven core part 8 on the other side of the clamping spring 12, a bore 13' of larger cross section which passes through the bearing sleeve 7 adjoining it.
The guide surfaces 9' plus driven core part 8 lie against the cup inner wall 15"" and thus increase the bearing length of the switch member 15. Three drivers 17 located at equal angular distance apart extend from the cup rim surface 15". They are shaped as axially protruding fingers and are integral with the switch member 15. The switch member 15 including the drivers 17 can be made of plastic. At the height of one driver 17 the switch member 15 is equipped with groove-shaped detent depressions 18, 19 and 19' which extend in axial direction and cooperate with a detent ball 20 of the driven core part 9. For this purpose, the driven core part 8 is provided on one of its angle bisectors with a blind core 21 to receive the detent ball 20 and a compression spring 22 which urges the ball in outward direction. In accordance with FIGS. 1 to 3, the protruding region of the detent ball 20 engages in form-locked manner into the central detent depression 18 so that in this position all drivers 17 are opposite the guide surfaces 9' of the driven core part 8 of triangular cross section. The two detent depressions 19, 19' which are directly adjacent the central detent depression 18 are enlarged in direction of rotation and provided with a concave bottom.
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