U.S. patent number RE34,680 [Application Number 07/742,886] was granted by the patent office on 1994-08-02 for screw tool.
This patent grant is currently assigned to Wera Werk Hermann Werner GmbH & Co.. Invention is credited to Karl Lieser.
United States Patent |
RE34,680 |
Lieser |
August 2, 1994 |
Screw tool
Abstract
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.
Inventors: |
Lieser; Karl (Wuppertal,
DE) |
Assignee: |
Wera Werk Hermann Werner GmbH &
Co. (Wuppertal, DE)
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Family
ID: |
6284865 |
Appl.
No.: |
07/742,886 |
Filed: |
August 9, 1991 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
98374 |
Sep 17, 1987 |
04884478 |
Dec 5, 1989 |
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Current U.S.
Class: |
81/59.1;
192/44 |
Current CPC
Class: |
B25B
15/04 (20130101); B25B 13/462 (20130101) |
Current International
Class: |
B25B
13/00 (20060101); B25B 15/04 (20060101); B25B
13/46 (20060101); B25B 15/00 (20060101); B25B
013/00 () |
Field of
Search: |
;81/59.1,63.1
;192/38,44,45 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2244222 |
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Mar 1973 |
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DE |
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2240922 |
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Mar 1974 |
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DE |
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2503372 |
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Jul 1975 |
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DE |
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2705134 |
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Aug 1978 |
|
DE |
|
3344361 |
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Apr 1985 |
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DE |
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Primary Examiner: Smith; James G.
Attorney, Agent or Firm: Farber; Martin A.
Claims
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, wherein
said 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, wherein
said 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, wherein
said 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, wherein
said 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, wherein
said 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, wherein
said 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, wherein
outer 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, wherein
said 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, wherein
said detent depressions provided 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, wherein
said 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, wherein
said drive ring part and said driven core part are relatively
rotatably mounted.
13. A screw tool according to claim 1, wherein
in 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, wherein
in said two switch positions of said switch member said drivers are
adjacent said clamping members.
15. A screw tool according to claim 8, wherein
said guide surfaces of said driven core part relatively rotatably
engage on an inner wall of said switch member. .Iadd.
16. In a screw tool with direction-reversible catch, the tool
comprising an outer ring part, and an inner core part of
approximately polygonal cross section;
a rotatable switch member having a plurality of drivers extending
therefrom and arranged circumferentially around said core part,
said switch member being lockable in a plurality of switch
positions;
plural clamping members disposed around said core part, said
clamping members being located in wedge-shaped clamping spaces
between said outer ring part and said inner core part, said
clamping members being displaceable by said rotatable switch
member, 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 to limit passage
of each clamping member within one of its two clamping
positions;
in two switch positions of the switch member, each of said clamping
members is loosely disposed in a separate one of said clamping
spaces and is displaceable into a clamping position therein by
rotation of the ring part;
in a central switch position of said switch member, each of said
clamping bodies is located substantially centrally of a
corresponding side of said core part;
vertices of said core part are arranged concentrically about said
core part to define 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 limit movement in circumferential direction within
each of said clamping spaces of said clamping members to a
predetermined region of unobstructed movement, a circumferential
length of said predetermined region of unobstructed movement being
greater than approximately twice the diameter of a clamping member.
.Iaddend. .Iadd.17. In a screw tool with direction-reversible
catch, the tool comprising an outer ring part, and an inner core
part of approximately polygonal cross section;
a rotatable switch member having a plurality of drivers extending
therefrom and arranged circumferentially around said core part,
said switch member being lockable in a plurality of switch
positions;
plural clamping members disposed around said core part, said
clamping members being located in wedge-shaped clamping spaces
between said outer ring part and said inner core part, said
clamping members being displaceable by said rotatable switch
member, 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 to limit passage
of each clamping member within one of its two clamping
positions;
in two switch positions of the switch member, each of said clamping
members is loosely disposed in a separate one of said clamping
spaces and is displaceable into a clamping position therein by
rotation of the ring part;
in a central switch position of said switch member, each of said
clamping bodies is located substantially centrally of a
corresponding side of said core part;
vertices of said core part are arranged concentrically about said
core part to define 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;
said core part carries a spring-loaded detent ball, and three
detent depressions are formed on a wall of said switch member for
providing three of said switch positions; and
said detent depressions include a central detent depression
corresponding to said central switch position which is operative in
both directions of rotation of said switch member and has a shape
complementary to said detent ball, said detent depressions further
comprising two further detent depressions disposed on opposite
sides of said central detent depression, the two further detent
depressions being enlarged relative to the central depression in
the directions of rotation of said switch member. .Iaddend.
.Iadd.18. A screw tool according to claim 17, wherein
said polygonal cross section is a triangular cross section.
.Iaddend. .Iadd.19. A screw tool according to claim 17, wherein
each of said further detent depressions is formed with a curved
concave
surface. .Iaddend. .Iadd.20. A screw tool according to claim 19,
wherein
a radius of curvature of the concave surface of each of said
further detent depressions is larger than a radius of curvature of
said detent ball. .Iaddend. .Iadd.21. A screw tool according to
claim 17, wherein
a cross-sectional dimension of each of said further detent
depressions is larger than a cross-sectional dimension of said
detent ball. .Iaddend. .Iadd.22. A screw tool according to claim
17, wherein
an enlargement of each of said further detent depressions relative
to said central depression is sufficient to allow for movement of
the detent ball in either of said further detent depressions in a
direction of rotation of
said switch member. .Iaddend. .Iadd.23. In a screw tool with
direction-reversible catch, the tool comprising an outer ring part,
and an inner core part of generally polygonal cross section;
a rotatable switch member having a plurality of drivers extending
therefrom and arranged circumferentially around said core part,
said switch member being lockable in a plurality of switch
positions;
plural clamping members disposed around said core part, said
clamping members being located in wedge-shaped clamping spaces
between said outer ring part and said inner core part, said
clamping member being displaceable by said rotatable switch member,
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 to limit passage
of each clamping member within one of its two clamping
positions;
in two switch positions of the switch member, each of said clamping
members is loosely disposed in a separate one of said clamping
spaces and is displaceable into a clamping position therein by
rotation of the ring part;
in a central switch position of said switch member, each of said
clamping bodies is located substantially centrally of a
corresponding side of said core part;
vertices of said core part are arranged concentrically about said
core part to define 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;
said core part carries a spring-loaded detent element having a
curved surface, and three detent depressions are formed on a wall
of said switch member for providing three of said switch positions;
and
said detent depressions include a central detent depression
corresponding to said central switch position which is operative in
both directions of rotation of said switch member and has a shape
complementary to said detent element, said detent depressions
further comprising two further detent depressions disposed on
opposite sides of said central detent depression, the two further
detent depressions being enlarged relative to the central
depression in the directions of rotation of said switch member to
permit movement of said detent element within either of said
further detent depressions. .Iaddend. .Iadd.24. A screw tool with
direction-reversible catch, the tool comprising
an outer ring part, and an inner core part of approximately
polygonal cross section;
a rotatable switch member having a plurality of drivers extending
therefrom and arranged circumferentially around said core part,
said switch member being lockable in a plurality of switch
positions;
plural clamping members disposed around said core part, said
clamping members being located in wedge-shaped clamping spaces
between said outer drive ring part and said core part, said
clamping members being displaceable by said rotatable switch
member, 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 to limit passage
of each clamping member within one of its two clamping
positions;
in two switch positions of the switch member, each of said clamping
members is disposed in a separate one of said clamping spaces and
is displaceable into a clamping position therein by rotation of
said ring part relative to said core part;
constrictions of said clamping spaces are arranged concentrically
about said core part, said drivers being located at respective ones
of said constrictions and being translatable in circumferential
direction through respective ones of said constrictions upon
rotation of said switch member about said core part;
said screw tool further comprises detent means for positioning said
switch member relative to the constrictions of said clamping
spaces, said detent means including a detent element movable in
radial direction and fixed in circumferential direction relative to
said constrictions, said detent means including an arrangement of
detent depressions disposed on said switch member for receiving
said detent element; and
a first and a second of said detent depressions are disposed on
opposite sides of a center of said arrangement of detent
depressions, said first and said second detent depressions being
enlarged relative to said detent element in the directions of
rotation of said switch member to permit movement of said detent
element within either of said first and said
second detent depressions. .Iaddend. .Iadd.25. A screw tool with
direction-reversible catch, the tool comprising
an outer ring part, and an inner core part of generally polygonal
cross section;
a rotatable switch member having a plurality of drivers extending
therefrom and arranged circumferentially around said core part,
said switch member being lockable in a plurality of switch
positions;
plural clamping members disposed around said core part, said
clamping members being located in wedge-shaped clamping spaces
between said ring part and said core part, said clamping members
being displaceable by said rotatable switch member, 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 to limit passage
of each clamping member within one of its two clamping
positions;
in two switch positions of the switch member, each of said clamping
members is disposed in a separate one of said clamping spaces and
is displaceable into a clamping position therein by rotation of
said ring part relative to said core part;
constrictions of said clamping spaces are arranged concentrically
about said core part, said drivers being located at respective ones
of said constrictions and being translatable in circumferential
direction through respective ones of said constrictions upon
rotation of said switch member about said core part; and
said screw tool further comprises a spring-loaded detent element
having a curved surface, and an arrangement of plural detent
depressions are formed on a wall of said switch member for
receiving said detent element to provide said switch positions;
and
a first and a second of said detent depressions are disposed on
opposite sides of a center of said arrangement of detent
depressions, said first and said second detent depressions being
enlarged relative to said detent element in the direction of
rotation of said switch member to permit movement of said detent
element within either of said first and said
second detent depressions. .Iaddend. .Iadd.26. A screw tool with
direction-reversible catch, the tool comprising
an outer ring part, and an inner core part of approximately
polygonal cross section;
a rotatable switch member having a plurality of drivers extending
therefrom and arranged circumferentially around said core part,
said switch member being lockable in a plurality of switch
positions;
plural clamping members disposed around said core part, said
clamping members being located in wedge-shaped clamping spaces
between said ring part and said core part, each of said
wedge-shaped clamping spaced having two clamping positions at
opposite ends of a clamping space for receiving and clamping one of
said clamping members;
wherein said clamping members are displaceable by said switch
member into a clamping position of a respective clamping space and
provide a clamping upon rotation of said ring part relative to said
core part;
said drivers are operable to limit passage of each clamping member
within its clamping space to one of its two clamping positions;
constrictions of said clamping spaces are arranged concentrically
about said core part, said drivers being located at respective ones
of said constrictions and being translatable in circumferential
direction through respective ones of said constrictions upon
rotation of said switch member about said core part; and
said drivers limit movement in circumferential direction within
each of said clamping spaces of said clamping members to a
predetermined region of unobstructed movement, a circumferential
length of said predetermined region of unobstructed movement being
greater than approximately twice the diameter of a clamping member.
.Iaddend.
Description
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a screw tool.
A screw tool is known from Federal Republic of Germany OS 3 344
361, in which the driven core part of triangular cross section
forms with the outer drive ring part the wedge-shaped clamping
spaces for the reception of roller-shaped clamping members arranged
in pairs. Between each pair of clamping members there extends a
compression spring which acts on them and presses the clamping
members into the wedge-shaped clamping spaces. The shifting of the
clamping members in order to obtain different directions of drive
is effected by means of the centrally mounted switch member from
which drivers bent off at an angle extend. In this connection,
three such drivers are provided, they extending in each case
between a pair of the clamping members. For the free rotatability
of the drivers the triangle corners are cut off concentricaly to
the center of rotation so that the drivers can move there into the
adjacent clamping spaces, regardless of the direction in which the
driving of the driven core part is desired. For the fixing of the
switch member in its switch positions there is provided a detent
ball which is arranged in the driven core part and which cooperates
with the switch member. Aside from the structural shape which is
expensive from a standpoint of manufacture, as a result of the
large number of structural parts, unfavorable frictional conditions
exist which upon longer use of the screw tool, lead to premature
phenomena of fatigue.
SUMMARY OF THE INVENTION
The object of the present invention is to simplify the construction
of a screw tool of the type in question and develop it in such a
manner that friction is minimized so as to obtain optimum operating
conditions. This object is achieved by one clamping member each
(24, 58) lies loosely in it clamping space and is displaceable into
its clamping position by the rotation of the drive ring part (3,
34).
As a result of this development, a screw tool of this type which is
of increased value of use is obtained. The construction of the
screw tool is simplified because of the reduced number of parts. It
has been found that three clamping members are sufficient in order
to obtain the desired action. If the switch member and thus the
drive means are in a neutral central position then the driven core
part is carried along upon the rotation of the drive ring part in
each direction, the clamping members being carried along into their
clamping position exclusively by the rotation of the drive ring
part. If, on the other hand, driving in one direction and free
travel in the other direction are desired, then the switch member
must be turned into the corresponding position, in which case the
drivers block the access to one clamping corner of the clamping
space. Upon drive along in rotation the clamping members now engage
into the corresponding clamping corners. A turning of the drive
ring part in the direction of free travel then leads to the rolling
of the clamping members out of said clamping corners. It has been
found that this loose insertion of the clamping members results in
a reduction in friction of about 20% as compared with traditional
structural shapes so that premature phenomena of fatigue upon
lengthy operation of the screw tool are counteracted. This is of
particular importance when the screw tool is developed as a
screwdriver. Barreling of the sides of the triangular driven core
part leads to a continuous guiding of the clamping members into the
corresponding clamping corners of the clamping spaces. In this way
protection against overload is obtained which leads to a
lengthening of the life of the screw tool. In order to develop the
barreled triangle sides free from incisions, the driven core part
bears the spring-loaded detent ball in a blind hole along one of
its angle bisectors. The corresponding detent depressions which
cooperate with the ball are located on the inner wall of the
cup-shaped switch member. In this way defined switch positions can
be favorably obtained so that the drivers of the switch member
which are developed as axially protruding fingers enter in
accordance with their purpose into the corresponding position. A
stable supporting feature of the switch member is the driven core
part which has concentrically extending guide surfaces which are
transverse to the angle bisectors and rest against the cup inner
wall of the switch member. The bearing length of the switch member
is further increased by the central guide collar of the driven core
part which enters into the bore in the bottom of the cup of the
switch member. The guide sleeve provides a low-friction and
nevertheless stable support for the driven core part. The guide
sleeve which is equipped with bearing ribs and is arranged turnably
in the inner body of the screwdriver handle. This inner body is a
part of the drive ring part, which leads to a further saving of
structural parts. Furthermore, the ribs are provided on the end
regions of the guide sleeve so that even large canting forces are
dependably counteracted. A stable interpolation is assured the
roller-shaped clamping members so that a part of their end surface
rests against bottom surfaces whichare formed in the region of the
clamping spaces by protrusions of the driven core part. It is
possible to produce the barrelled sides of the triangle in the case
of polygonal turning by means of single-tooth fly cutter. This also
results in the outer edges of the bottom surfaces and of the guide
surfaces supplementing each other to form a circle, together with
advantages from a manufacturing standpoint. Optimum control of the
clamping members is obtained by the drivers of the switch member
which extend to the bottom surfaces. In this way the axial length
of the clamping members corresponds to that of the drivers. The
surface of the cup edge of the switch member secures the position
of the clamping members in the other direction by gripping the
other end surfaces of the roller-shaped clamping members. The
detent depressions thereof are so developed that the middle one
corresponds in a form-locked manner to the ball entrance cross
section. The two adjacennt detent depressions are, however,
enlarged in the direction of rotation and provided with a concave
bottom. Depending on the direction of rotation of the switch
member, the detent ball then dips into the corresponding adjacent
detent depression and is brought into the centering position by the
compression spring which acts upon it. In this way, the switch
member can move over a larger path and this embodiment also makes
it possible, upon displacement of the drive ring part in the
direction of free-travel, for a slight evasion movement of the
drivers to also be obtained without the switch member moving out of
its switch position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows in enlarged size a longitudinal section through the
screw tool according to the first embodiment associated with a
screwdriver handle, the switch member being in the center
position.
FIG. 2 is a section along the line II--II of FIG. 1.
FIG. 3 is a section along the line III--III of FIG. 1.
FIG. 4 is a section corresponding to FIG. 2, the switch member
being shifted into a different switch position in order to change
the direction of drive.
FIG. 5 is a section similar to FIG. 3, but with the switch ring
shifted.
FIG. 6 shows on a larger scale a longitudinal section through the
screw tool in accordance with the second embodiment.
FIG. 7 is a section along the line VII--VII of FIG. 6.
FIG. 8 is a view corresponding to FIG. 7 but with the switch member
turned into the one switch position.
FIG. 9 is also a cross section corresponding to FIG. 7, with the
switch member moved into the other switch position.
FIG. 10 is a section along the line X--X of FIG. 6, and
FIG. 11 is a section along the line XI--XI of FIG. 8.
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 baring 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 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 collar 11 of the driven core part 8 passes through a bore
14 in the cup bottom 15' of a cup-shaped switch member 15. The cup
rim surface 15" thereof extends in front of the transition step
between the bore sections 4 and 5 and forms there an outwardly
directed collar 15'". A lock spring washer 16 which engages into an
inner groove 4' of the bore section 4 places itself in front of
said collar and holds the switch member 15 and thus also the driven
core part 8 in its axially non-displaceable position with respect
to the drive ring part 3.
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 12 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.
The inner surfaces 17' of the drivers 17 are aligned with the cup
inner wall 15"" while the outer surfaces 17" are guided by the wall
of the bore section 5 of the drive ring part 3. Otherwise, the
drivers 17 extend up to the protrusions 10 of the driven core part
8; see FIG. 1.
Between the triangle sides 9 of the driven core part 8 and the wall
of the bore section 5 clamping spaces 23 are formed. Each of these
clamping spaces 23 forms clamping cornners 23' in its
circumferential end regions. In each clamping space 23 there
loosely lies a roller-shaped clamping member 24. In the central
switch position of the switch member 15 the clamping members 24 lie
approximately on a line with the vertex of the barreled triangle
sides 9; see FIGS. 2 and 3.
The roller-shaped clamping members 24 have a part of their one end
surface 25 in front of the bottom surfaces 10" of the protrusions
10 and are accordingly secured in position in one direction by
them. The securing in position in the other direction is imparted
to the clamping members 24 by the cup rim surface 15" of the switch
member 15 which engages over the other end surface 26. Since the
drivers 17 extend to the bottom surfaces 10" of the protrusions 10
or even slightly beyond them, along radial control surfaces 17'"
are present on the drivers 17.
This embodiment operates as follows:
If the switch member 15 is in the central switch position (see
FIGS. 1 to 3), then, upon the turning of the screwdriver handle 1,
the driven core part 8 is carried along in each direction by means
of the drive ring part 3, due to the entraining of the clamping
members 24 into the corresponding clamping corners 23'. Free travel
then does not take place.
If, on the other hand, the driven core part 8 is to be carried
along in the direction of the arrow y in accordance with FIGS. 4
and 5, then the switch member 15 must be turned in such a way that
the detent ball 20 engagably enters the detent depression 19. The
drivers 17 extending from the switch member 15 thereby displace the
clamping members 24 by a certain amount from their center position
in the direction towards the corresponding clamping corner 23' of
the clamping spaces 23. If the drive ring part 3 or the screwdriver
handle 1 is now turned in the direction indicated by the arrow y,
then, due to friction, this displaces the clamping members into the
clamping position so that in this way the driven core part 8 is
also rotates in the direction indicated by the arrow y. Upon the
opposite direction of rotation, the clamping members 24 are
displaced from the corresponding corners 23', which corresponds to
free travel. The drivers 17 and thus the switch member 15 can
possibly be turned slightly by the clamping members 24.
Nevertheless, the detent ball 20 remains in its detent depression
19.
If the driven core part 8 is to be driven in the other direction of
rotation, then the switch member 15 must be turned in such a way
that the detent ball 20 enters into the detent depression 19'.
In accordance with the second embodiment, shown in FIGS. 6 to 11,
the screw tool has a screwdriver handle 32 to receive the sleeve 33
of a drive ring part 34. Within the sleeve 33 there is rotatably
arranged a bearing bushing 35 of a driven core part 36. In order to
obtain reduced friction between the sleeve 33 and the bearing
bushing 35, the bearing bushing 35 forms an annular groove 37 into
which bearing balls 38 of the sleeve 33 engage. The bearing balls
38 are seated in three radial bores 29 of sleeve 33 which are
arranged at equal circumferential distances apart; see in
particular FIG. 10. At the place of the radial bores there is a
spring washer 40 which is introduced from the outside into the
sleeve 33. It prevents plastic material from coming into the radial
bores 39 upon the spraying-on of the handle 32 which is to be made
from plastic.
A bore 41 is produced starting from the end surface 34' of the
drive ring part 34. Within it the driven core part 36 which forms
an equilateral driven triangle is rotatably mounted in such a
manner that the vertices 36' of the triangle are guided on the
inner wall 41' of the bore 41.
The bearing bushing 35 of the driven core part 36 rotatably
receives a stepped tubular shank 42 of a tool-holder sleeve 43. The
sleeve is hexagonal in cross section and the end of it which faces
the shank 42 enters in form-locked manner into a triangular recess
44 in the driven core part 36. The inner surfaces 44' of the
triangular recess 44 extend in this connection parallel to the
triangle sides 36" of the triangular drive core part 36. In this
way, wall sections 45 which are directed along a triangle are
created which come into form-lock with the corresponding polygonal
surfaces of the tool-holder sleeve 43. The outer end surfaces 45'
of these wall sections 45 which form triangle sides are beveled.
The recess 44 is opened in the region of the vertices 36' of the
triangle by slitting 46. In this way, detent depressions 47 are
formed in the region of the triangle vertices 36' to receive detent
balls 48 which form the drivers. The detent balls extend in bores
49 of a switch member 50 which is rotatably associated with the
drive ring part 34. Three detent balls 48 are provided
corresponding to the triangular driven core part and accordingly
also three bores 49 spaced circumferentially equally apart. The
detent balls 48 are acted on by compression spring 51 which press
the detent balls 48 into the detent depressions 47. For turnable
association, the switch member 50 forms on its end surfaces facing
the drive ring part 34 an edge-side collar 52 which extends into an
edge-side annular groove 53 of the drive ring part 34. For the
passage of the tool-holder sleeve 43, the switch member 50 forms a
central bore 54. The latter is so large that turnability of the
switch member 50 is assured. The switch member 50 is imparted
assurance against being pulled off by a lock washer 55 of the
tool-holder sleeve 43 on which lock washer 55 the switch member 50
rests.
The tool-holder sleeve 43 on its part is also secured against being
pulled off by a lock washer 56. The latter is seated on the end of
the shank 2 of the tool-holder sleeve which extends beyond the
bearing bushing 35 and rests against the end surface there of the
bearing bushing 35.
The tool-holder sleeve 43 is provided on its inside with a
polygonal edge 57 for the insertion of the tool, in order to be
able to drive the latter.
As coupling means between driven core part 36 and drive ring part
34 there are employed clamping members 53. The latter are located
in the region between the inner wall 41' of the bore 41 of the
drive ring part 34 and the wall sections 45 of the driven core part
36. In this way three segment-like clamping spaces are created. The
roller-shaped clamping members 58 are located in the region of the
largest radial dimension of these spaces. The clamping members
extend to the bottom of the bore 41 and terminate flush with the
end surface 34' of the drive ring part 34 and thus also with the
end surface of the driven core part. The ends there of the clamping
members are provided with frustoconical bevels 58'. Each clamping
member 58 forms a space divider so that clamping corner 59, 60
which extend in wedge shape on both sides thereof are produced.
The manner of operation of the screw tool last described is as
follows:
If the switch member 50 assumes its central position in accordance
with FIGS. 6 and 7, then the detent balls 48 lie in the detent
depressions 47 within the region of the vertices 36' of the
triangle. Upon the turning of the handle 32 or of the drive ring
part 34 which is connected, fixed for rotation, with it, the driven
core part 36 is carried along in both directions of rotation.
If it is desired that the driven core part 36 be carried along in
the direction of the arrow x in FIG. 8, then the switch member 50
must also be turned in that direction. In this case the detent
balls 48 are carried along. They pass through the one slit and pass
into the corners 59. There they receive a threefold support, in
that they come against the inner wall 41', against the outer
surface of the clamping members 58, and against the beveled end
surfaces 45' of the wall section 45. In this way the clamping
members 48 are urged in the direction of the clamping corners 60 so
that upon rotation of the drive ring part 34 in the direction
indicated by the arrow x the driven core part 36 is driven along.
An oppositely directed rotary movement of the drive ring part, on
the other hand, does not lead to any driving along of the drive
core part 36 so that this is the free travel.
FIG. 11, in particular, shows that in the switch position the
detent ball 48 cannot rest on the bottom of the bore 41 of the
drive ring part 34. This is important in order to permit the
bringing back of the switch member ring into the central position,
in which connection the detent balls after passing through the
corresponding slit pass into the detent depressions 47.
In accordance with FIG. 9, the switch member ring 50 has been
turned in the direction of the arrow y. In this way the detent
balls 48 also have left the detent depressions 47 and have entered
into the clamping corners 60. There they also receive a three-point
support and push the clamping members into the clamping corners 59.
Upon a turning of the drive ring part 34 in the direction of the
arrow y, the driven core part 36 is therefore also carried along in
the direction of this arrow. The opposite rotation of the drive
core part then corresponds to the direction of free travel.
* * * * *