Tools – Wrench – screwdriver – or driver therefor – Handle clutched to head
Reexamination Certificate
2002-05-02
2003-02-25
Meislin, D. S. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Handle clutched to head
C192S043100, C081S062000
Reexamination Certificate
active
06523439
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is related to an improved ratchet structure of a screwdriver, and more particularly to a ratchet structure in which the middle sections of the left and right dogs of the ratchet mechanism are respectively supported by projecting sections of a seat body. By means of turning the cap member, the swinging positions of the left and right dogs can be switched so as to more truly and conveniently operate the ratchet mechanism.
FIGS. 6
to
8
show a conventional ratchet screwdriver. The handle
8
is formed with a cavity
81
through which a stem
82
is fitted. A section of the stem
82
in the cavity
81
is a toothed section
821
. The handle
8
is further formed with two pairs of radially opposite chambers
83
communicating with the cavity
81
. A leaf spring
84
and a dog
85
are disposed in each chamber
83
. The leaf spring
84
pushes the dog
85
to engage with the toothed section
821
of the stem
82
. The center of inner face of the upper cap
86
is formed with a circular projecting block
87
. The projecting block
87
has two radially oppositely extending projecting sections
871
. When turning the upper cap
86
, the two projecting sections
871
respectively push away the opposite dogs
85
to change the rotational direction of the stem
82
driven by the handle
8
. In addition, the inner side of the upper cap
86
is formed with a projecting locating block
88
. The handle
8
is formed with three locating sections
89
corresponding to the locating block
88
. The locating sections
89
are respectively formed in three positions where different dogs
85
are respectively pushed away by the projecting sections
871
of the projecting block
87
and where no dogs
85
are pushed away by the projecting sections
871
. Accordingly, the locating block
88
can locate the upper cap
86
in any of the three positions.
According to the above structure, the two projecting sections
871
of the circular projecting block
87
extend radially opposite to each other. The edges of the projecting sections
871
are formed with two guide faces
872
adjacent to the projecting block
87
. A stop face
873
is formed between each two guide faces
872
. The four chambers
83
also radially extend as the projecting sections
871
. Therefore, the guide faces
872
are nearly parallel to the lateral sides of the dogs
85
disposed in the chambers
83
. As a result, it is laborious to turn the upper cap
86
and make the guide faces
872
of the projecting sections
871
push away the dogs
85
. Furthermore, under limitation of the dimension of the cavity
81
, the size of the projecting sections
871
cannot be freely enlarged. Accordingly, when turning the upper cap
86
to make the stop faces
873
of the projecting sections
871
respectively push away the dogs
85
, the dogs
85
are retracted into the chambers just in flush with the outer circumference of the cavity
81
as shown in FIG.
8
. The toothed section
821
of the stem
82
can just pass over the dogs
85
. However, after a period of use, the stop faces
873
will be inevitably worn and depressed, so that the stop faces
873
will be unable to fully push the dogs
85
away from the cavity
81
. As a result, the toothed section
821
of the stem
82
will collide the dogs
85
and the ratchet mechanism can be hardly truly operated.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide improved ratchet structure of a screwdriver in which the middle sections of the left and right dogs of the ratchet mechanism are respectively supported by the projecting sections of the seat body. In addition, the left and right dogs are respectively pushed by two springs to engage with the toothed section of the stem. When turning the cap member, the projecting block in the cap member can easily push and deflect the left dog or right dog and truly disengage the left dog or right dog from the toothed section of the stem. Accordingly, the ratchet screwdriver can be more conveniently and truly operated.
It is a further object of the present invention to provide the above ratchet structure in which the steel ball disposed in the receptacle and the two ball bodies disposed in the left and right through holes together support the inner circumference of the cap member so as to reduce the frictional resistance against the cap member when turned. Therefore, the cap member can be more smoothly turned.
The present invention can be best understood through the following description and accompanying drawings wherein:
REFERENCES:
patent: 6206160 (2001-03-01), Chen
patent: 6227077 (2001-05-01), Chiang
Meislin D. S.
Rosenberg , Klein & Lee
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