Note: Descriptions are shown in the official language in which they were submitted.
CA 02356549 2001-10-05
1 Biasing Arrangement for a Pawl of a Reversible Ratchet-Tyue Wrench
2 Background of the Invention
3 1. Field of the Invention
4 The present invention relates to a biasing arrangement for a pawl of a
reversible
ratchet-type wrench to provide reliable ratcheting. The present invention also
relates to an
6 improved head structure for a ratchet-type wrench to lower the manufacture
cost.
7 ~ . Description of the Related Art
8 U.S. Patent No. 2,957,377 issued to Hare on Oct. 25, 1960 discloses a
reversible ratchet
9 type wrench comprising a body 10 having a handle 11 and a head 12. A cap 39
and an annular
wall 44 are provided to upper side and lower side of the head 12,
respectively. Yet, this
11 increases the assembly time and the manufacture cost and adversely affects
the appearance. A
12 shifting lever 35 is retained in place by a spring 33 that is located in a
cylindrical opening 34.
13 rJevertheless, formation of the cylindrical opening 34 that extends
inclined upward is
14 relatively difficult. In addition, formation of the cavity 16 having
converging straight sides 17,
18 which diverge in the direction of the periphery of rotatable member 14
requires expensive
16 and accurate computer-numeric-controi (CNC), which further results in an
increase in the cost
17 together with a low production rate. This is why such reversible ratchet
type wrench is hardly
18 seen in the market.
19 Figs. 10 and 11 illustrate another conventional ratchet type wrench
comprising a handle
12' and a head 11'. The head 11' is machined to form four consecutive
compartments for
21 receiving the drive member 20', the pawl 30' and the shifting lever 40',
wherein three of the
22 compartments can be formed by cutting, yet the remaining one must be
machined by CNC.
23 Further, the resultant head structure ins relatively weak and thus has a
poor torque-bearing
24 capacity. In addition, the movement of the pawl 30' for changing ratcheting
direction is found
unreliable, as it is achieved via transmission of the hook end 442' of a
spring 44' attached to
26 tlhe shifting lever 40'.
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Summary of the Invention
In accordance with the invention, a reversible
ratchet-type wrench comprises:
a handle;
a head extended from the handle;
a drive member rotatably mounted in the head, with
the drive member including a plurality of teeth formed on an
outer periphery thereof;
a pawl including a first side with a plurality of
ratchet teeth for releasably engaging with the teeth of the
drive member, with the pawl further including a second side
with a recess;
a rotatably switch member including a turn-piece
for manual operation and an actuating plate extended from
the turn-piece, the switch member being switchable between
two positions for changing ratcheting direction of the drive
member, with the actuating plate of the switch member
including a first receptacle that faces the recess of the
pawl and that has a first end wall;
an elastic element; and
a pin, with the pin having a first end movably
received in the recess of the pawl and a second end, with
the second end of the pin being received in the first
receptacle and including a second receptacle with a second
end wall, with the elastic element located in the first and
second receptacles between the first end wall and the second
end wall, with the pin and the elastic member being
rotatable with actuating plate and biasing the ratchet teeth
of the pawl to engage with the teeth of the drive member.
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In an embodiment of the invention, the drive
member is a gear wheel including an inner periphery adapted
to drive a fastener.
In another embodiment of the invention, the drive
member includes a drive column for releasably engaging with
a socket.
In an embodiment of the invention, the head
includes an end wall with an opening, and the drive member
includes a stub rotatably received in the opening.
The drive member is rotatably mounted in hole of
the head. An inner periphery defining the hole of the head
includes a first annular groove, and the outer periphery of
the drive member includes a second annular groove. The
reversible ratchet-type wrench further comprises a C-clip
received in the first annular groove and the second annular
groove, thereby rotatably retaining the drive member in the
head.
The drive member includes a top and a bottom. The
outer periphery extends between the top and a bottom, and
the second annular groove is spaced from the top and the
bottom.
The switch member is rotatable about an axis. The
actuating plate extends in a direction parallel to the axis
of the switch member from the turn-piece.
The pin has a periphery extending from the second
end thereof. The periphery of the pin is of a size for
slidable receipt within the first receptacle. The second
receptacle is located within the periphery of the pin.
Preferably, the second receptacle is spaced from the
periphery of the pin.
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A web is defined between the handle and the head.
A cavity is defined in the web. The pawl has a first end
and an opposite end. The first end of the pawl engages a
wall portion defining the cavity in one of the two positions
of the switch member and the opposite end of the pawl
engages another wall portion defining the cavity in the
other of the two positions of the switch member.
Other objects, advantages, and novel features of
the invention will become more apparent from the following
detailed description when taken in conjunction with the
accompanying drawings.
Brief Description of the Drawings
Fig. 1 is an exploded perspective view of an end
portion of a first embodiment of a ratchet-type wrench in
accordance with the present invention.
Fig. 2 is a sectional view of the end portion of
the first embodiment of the ratchet-type wrench in
accordance with the present invention.
Fig. 3 is a top view, partly sectioned, of the end
portion of the first embodiment of the ratchet-type wrench
in accordance with the present invention, wherein the wrench
is in a status allowing counterclockwise ratcheting.
Fig. 4 is a view similar to Fig. 3, wherein the
wrench is in a status allowing free rotation in both
directions.
Fig. 5 is a view similar to Fig. 3, wherein the
wrench is in a status allowing clockwise ratcheting.
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Fig. 6 is a perspective view of the end portion of
the first embodiment of the ratchet-type wrench in
accordance with the present invention.
Fig. 7 is a sectional view illustrating a second
embodiment of the ratchet-type wrench in accordance with the
present invention.
Fig. 8 is a top view of an end portion of a third
embodiment of the ratchet-type wrench in accordance with the
present invention.
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1 Fig. 9 is a sectional view illustrating a fourth embodiment of the ratchet-
type wrench in
2 accordance with the present invention.
3 Fig. I O is an exploded perspective view of a conventional ratchet type
wrench.
4 Fig. 11 is a sectional view of a head portion of the conventional ratchet
type wrench in
Fig..10.
6 Detailed Description of the Preferred Embodiments
7 Referring to Figs. 1 through 9 and initially to Figs. 1, 2, 3, and 6, a
ratchet-type wrench
8 10 in accordance with the present invention generally includes a handle 12
and a head 11
9 having a hole 13. An inner periphery 132 defining the hole 13 of the head 11
includes an
IO annular groove 131 in a lower portion thereof. A web 17 is defined between
the head 11 and
I1 the handle 12. A cavity 14 is defined in the web 17. Also defined in the
web 17 is a
12 compartment I S that is substantially L-shape and includes an inner end
communicated with
13 the cavity 14 and an outer end communicated with outside, thereby leaving a
bridge 16 on the
14 web 17. The outer end of the compartment 15 is preferably circular. The
bridge I6 increases
I S the strength of the head 11 and the handle 12, thereby providing a higher
torque-bearing
16 capacity.
17 ~ A drive member (in the form of a gear wheel 20 in this embodiment) is
mounted in the
18 head I1 and includes an inner periphery 24 for driving a fastener (not
shown) and an outer
19 periphery 25. The outer periphery 25 includes a recessed upper end portion
22, a lower end
20 portion 23, and a middle portion with a plurality of recessed teeth 21. The
Lower end portion
2I 23 includes an annular groove 231. A C-clip 30 is received in the annular
groove 231 of the
22 lower end portion 23 and the annular groove 131 of the head I3, thereby
rotatably retaining
23 the gear wheel 20 in the head 11 of the wrench 10, best shown in Fig. 2.
24 A pawl 40 is mounted in cavity 14 in the web 17 and includes ratchet teeth
41 on a side
25 thereof for engaging with teeth 21 of the gear wheel 20. The other side of
the pawl 40 further
26 includes a recess 42 having two ends 42I and 422, which will be described
later.
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1 Still refernng to Figs. 1 through 3, a switch member 50 is rotatably mounted
~to the
2 second end of the compartment 15. In this embodiment, the switch member 50
includes a
3 turn-piece 51 outside the compartment 15 for manual operation and an
actuating plate 52
4 ' extended from the turn-piece 51 and having a receptacle 521 that faces the
cavity 14. A
biasing means 60 is mounted in the receptacle 521 and includes an elastic
element 62 and a
6 pin 61: In tills ernbodimenf;: as illustrated in Fig. Z; the elastic element
62 includes a $rst end
7 621 conf gored to bias an end 612 of the pin 61. A second end 622 of the
elastic element 62 is
8 configured to have a larger diameter so as to bear against and thus be
attached to the actuating
9 plate 52 in an area surrounding an opening section (not labeled) of the
receptacle 521, as
' shown in Fig. 3 .
11 In assembly, the switch member 50 is mounted in the compartment 15 and the
biasing
12 means 60 is mounted into the receptacle 521 of the switch member 50 via the
cavity 14 with
13 the elastic element 62 surrounding a part of the pin 61. The end 6 i 2 of
the pin 6 bears
14 against the first end 621 of the elastic element 62. The pawl 40 is mounted
into the cavity 14
with the other end 612 of the peg 61 extended into the recess 42 of the pawl
40. The C-clip 30
16 is placed into the hole 132 and the gear wheel 20 is then mounted in the
hole 132 with the
17 C-clip 30 received in the annular grooves 13 l and 231, thereby completing
the assembly. Thus,
18 the assembly procedure is simple and can be accomplished quickly by a C-
clip 30 without the
19 aid of any screw or cover.
The ratchet-type wrench in Fig. 3 is in a status allowing counterclockwise
ratcheting
21 (free rotation in clockwise direction), in which the other end 611 of the
pin 6i bears against an
22 end 422 of the recess 42 of the pawl 40, and an end 44 of the pawl 40 bears
against a wall
23 portion defining the cavity 14. When a change in the ratcheting direction
is required, the user
24 may switch the turn-piece 51 and thus cause the biasing means 60 to move.
Fig. 4 shows a
transition position for the ratchet-type wrench that allows free rotation in
both directions. As
26 illustrated in Fig. 4, the elastic element 62 is stretched during
rotational movement of the
27 turn-piece. When the turn-piece 51 reaches its predetermined position shown
in Fig. 5, the
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1 other. end f l l of the pin 61 bears against the other end 421 of the recess
42 of the pawl 40,
2 and the other end 43 of the pawl 40 bears against another wall portion
defining the cavity 14.
3 Thus, the ratchet-type wrench is in a status allowing clockwise ratcheting
and free rotation in
4 the counterclockwise direction.
Fig. 7 illustrates a second embodiment in accordance with the present
invention,
6 wherein the gear wheel 20 is replaced by a drive member 70 having a drive
column 73 with an
7 engaging means 80 for releasably engaging with a socket (not shown). The
drive member 70
8 includes an outer periphery having a plurality of teeth 71 for engaging with
the pawl teeth f1.
9 An annular groove 731 is defined in a lower portion of the outer periphery
of the drive
member 70 for engaging with the C-clip 30, which is identical to that
disclosed above. In
11 addition, the drive member 70 includes a stub 72 on a top thereof, and the
upper portion of the
12 head 11 is modified to include an end wall 133 with an opening 134 for
rotatably receiving the
13 stub 72 of the drive member 7Q, thereby providing stable rotational
movement for the drive
14 member ?0.
Fig. 8 illustrates a third embodiment in accordance with the present
invention. It is noted
16 that the biasing means (now designated by 90) in this embodiment includes a
pin 92 that is
17 having a receptacle 911 for receiving an end of the elastic element 92.
Thus, the elastic
18 element 92 is attached between an end wall (not labeled} defining the
receptacle 911 of the pin
19 92 and an end wall (not labeled} defining the receptacle 521 of the switch
member 50.
Fig. 9 illustrates a fourth embodiment in accordance with the present
invention. It is
21 noted that the biasing means 90 in the fourth embodiment is identical to
that of the third
22 embodiment, and the drive member 70 in the fourth embodiment is identical
to that of the
23 second embodiment.
24 Although the invention has been explained in relation to its preferred
embodiment, it is
to be understood that many other possible modifications and variations can be
made without
26 departing from the spirit and scope of the invention as hereinafter
claimed.
27
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