Note: Descriptions are shown in the official language in which they were submitted.
CA 02293796 2004-05-31
Ratchet Type Ring Spanner
Background of the Invention
Field of the Invention
The present invention relates to a ratchet-type ring
spanner and, more particularly, to an improved ring
spanner which is particularly useful for repairmen.
Description of the Related Art
Hand tools play a role in a civilized society, and
spanners are the most important one in the field of hand
tools since the invention of the bolts and nuts. A wide
variety of spanners have been available heretofore, such
as combination wrenches, open wrenches, ring spanners,
socket ratchet wrenches, etc. Fig. 6 of the drawings
illustrates a socket ratchet wrench which includes a
handle 40 and a switch button 41 mounted in a head
portion 42 to change a reversible direction a ratchet
mounted in the head portion 42 during operation. A
drawback of the socket ratchet wrench is that a user has
to hold the socket ratchet wrench with one hand and
switch the switch button 41 when changing the reversible
direction. A further drawback of the socket ratchet
wrench is that it has a relatively large head in order to
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accommodate complex elements required for the switching
operation, and thus cannot be used in a limited space.
A professional repairman would use combination
wrenches (see Fig. 7 of the drawing), open wrenches or
ring spanners in a limited space for tightening or
loosening nuts. A common drawback of these devices is
that, after being rotated through a small angle, the
device has to be removed from the nut and re-engaged with
the nut, which can then be rotated through another small
angle. This process continues until tightening or
loosening of the nut is accomplished. This process is
very inconvenient, especially in a limited space.
A reversible ring spanner has been proposed to solve
the above-mentioned drawbacks, such spanner includes a
ratchet wheel mounted in a head portion of the spanner
and a cavity defined in a web area of the spanner for
receiving a spring and a pawl. The pawl is biased by
the spring to engage with and disengage from the ratchet
wheel to provide the required ratchet operation. It is,
however, found that, as the typical pawl merely engages
with one tooth of the ratchet wheel, the maximum torque
is relatively small, and the pawl may be damaged if a
relatively large force is applied. In addition, it is
very difficult to provide a cavity in the web area of the
spanner with a thickness of one (1) centimeter.
Furthermore, the cavity must extend in an oblique manner
in order to assure proper engagement between the ratchet
wheel and the pawl, which further increases the
difficulty of provision of the cavity as the tolerable
error is extremely small. Although the problem can be
solved by increasing the thickness of the head of the
spanner, the enlarged head, like those of socket ratchet
wrenches, would not allow the spanner to be used
efficiently in a limited space.
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Therefore, there has been a long and unfulfilled
need for an improved ratchet-type ring spanner to
mitigate and/or obviate the above problem.
Summary of the Invention
It is an object of the present invention to provide
a ratchet-type ring spanner for professional repairmen
which can be operated easily and assembled conveniently.
It is another object of the present invention to
provide a ratchet-type ring spanner which still functions
reliably even if alien objects such as dirt enter the
head of the spanner.
A ratchet-type ring spanner in accordance with the
present invention comprises a handle and a head portion
which includes a circular peripheral wall defining a
receiving compartment therein and including a web area
which connects with the handle, a cavity being defined in
the web area. A ratchet wheel is received in the
compartment and includes a plurality of teeth in an outer
periphery thereof and a polygonal inner periphery for
engaging sides of a nut to be tightened or loosened.
A pawl is mounted in the cavity and includes a
plurality of teeth deffined on a ffirst side thereof for
engaging with the teeth of the ratchet wheel and a second
side bearing against a wall defining the cavity. A stop
member is mounted in the cavity and including a first end
bearing against the wall defining the cavity. A spring is
mounted between the stop member and the toothed member to
bias the toothed member away from the stop member. In one
embodiment of the invention, the first end of the stop
member includes two protrusions for bearing against the
wall defining the cavity.
In accordance with one aspect of the invention, the
toothed member includes a stub and the stop member
includes a post extending therefrom, while the spring has
a first end attached to the stub of the toothed member
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and a second end attached to the post of the stop member.
In accordance with a further aspect of the
invention, the stop member further includes a pair of
wings respectively extending outwardly from mediate
portions of two longitudinal edges thereof in a plane
substantially perpendicular to a longitudinal direction
thereof . The wings function as a guiding rail for the
toothed member for disengagement of the toothed member
from the ratchet wheel in the event an alien object
enters the cavity, thereby allowing the toothed member to
return to its initial position for subsequent operation
without being disturbed by the alien object.
In accordance with another aspect of the invention,
the wall defining the cavity includes a depression in a
mediate portion, while the stop member further includes
an anchor which is received in the depression.
Other obj ect s , 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 a perspective view of a part of a ratchet-
type ring spanner in accordance with the present
invention;
Fig. 2 is an exploded view of the ratchet-type ring
spanner in Fig. 1;
Fig. 3 is a cross-sectional view of the ratchet-type
ring spanner in accordance with the present invention;
Fig. 4 is a cross-sectional view similar to Fig. 3,
illustrating the operation of the ratchet-type ring
spanner under a normal condition;
Fig. 5 is a cross-sectional views similar to Fig. 3,
illustrating operation of the ratchet-type ring spanner
under the condition of intrusion of alien objects;
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Fig: 6 is a perspective view of a conventional
socket ratchet wrench;
Fig. 7 is a perspective view of a conventional
combination wrench; and
5 Fig. 8 is an exploded view of an second embodiment
of the ratchet-type ring spanner of the invention.
Description of the Preferred Embodiment
Referring now to Figs . 1 to 5 and initially to Figs .
1 to 3, a ratchet-type ring spanner in accordance with
the present invention is designated by reference numeral
"1" and generally includes a handle 11 and a head portion
10. The head portion 10 includes a circular peripheral
wall l0a defining a receiving compartment 12 for
receiving a ratchet wheel 20. The peripheral wall 10a
includes a web area lOb which connects with the handle
11. A cavity 13 is defined in the web area 10b and a
depression 131 is defined in a mediate portion of a wall
defining the cavity 13
(see Fig. 3).
Referring to Figs. 2 and 3, the ratchet wheel 20
includes a plurality of teeth 21 on its outer periphery
and has a polygonal inner periphery for engaging with
sides of a nut or the like . An arcuate toothed member 14 ,
or pawl, is mounted in the cavity 13 and includes a stub
141 formed on one end and a plurality of teeth 142
defined on a first side for engaging with the teeth 21 of
the ratchet wheel 20. Also mounted in the cavity 13 is a
stop member which is a resilient plate 15 including two
protrusions 151 and 152 formed on a first end and a
substantially U-shaped anchor 155 formed on a second end
and received in the depression 131. The resilient plate
15 further includes a post 156 extending outwardly from
a mediate portion of a side thereof and a pair of wings
153 and 154 respectively extending outwardly from mediate
portions of two longitudinal edges in a plane
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substantially perpendicular to a longitudinal direction
thereof.
In assembly, the stop member 15 is inserted into a
side of the cavity 13 in which the protrusions 151 and
152 of the first end of the stop member 15 firmly bears
against the wall defining the cavity 13, and the anchor
155 is received in the depression 131. The arcuate
toothed member 14 is then inserted into the other side of
the cavity 13 with a second side thereof bearing against
the wall defining the cavity 13 and with the stub 141
facing the post 1S6 of the stop member 15. A spring 16 is
mounted between the stop member 15 and the arcuate
toothed member 14 in which a f first end is attached to the
stub 141 and a second end is attached to the post 156, as
shown in Fig. 3. The ratchet wheel 20 is then inserted
into the receiving compartment 12 of the head portion 10
in which the teeth 21 engages with the teeth 142 on the
first side of the toothed member 14.
In operation, a nut (not shown) to be loosened or
tightened engages with the ratchet wheel 20 in a
conventional manner and the user may operate the ring
spanner at the handle 11 to urge the head portion 10 as
well as the nut to rotate in a first direction, e.g.,
clockwise. If the head portion 10 travels through a
certain angle, the toothed member 14 is moved to a
position shown in Fig. 4 (as the ratchet wheel 20 engages
with the toothed member 14) and the spring 16 is thus
compressed. When it is necessary to move the ring spanner
back to its initial position, the user needs not to lift
the ring spanner upwardly to disengage from the nut and
then lower the ring spanner for reengaging with the nut.
Instead, the user may directly move the ring spanner in
an opposite direction, e.g., counterclockwise, as it
provides a reversible function. This is because the
spring force provided by the spring 16 pushes the toothed
member 14 back to its initial position shown in Fig. 3,
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while the structures of the teeth 142 of the toothed
member and the teeth 21 of the ratchet wheel 20 allow
such rotation in the opposite direction.
If an alien object enters the cavity 13 of the head
portion, which tends to occur frequently during repair,
the toothed member 14, as being impeded by the alien
object, may not immediately move back' to its initial
position when the above-mentioned reverse travel is
required. This is because the toothed member 14 is not
allowed to disengage with the ratchet wheel 20. Under
this condition, the toothed member 14 is carried by
ratchet wheel 20 to move further rightwardly (as seen
from the direction of Fig. 4? and thus impinges the wings
153 and 154 of the stop member 15 which accordingly gives
a force to the stop member 15. The force results in a
normal force and a longitudinal force which cause the
toothed member 14 to slide along lateral edges 1531 and
1541 of the wings 153 and 154 for a certain distance (see
the arrow in Fig . 5 ) and thus disengages from the ratchet
wheel 20, as shown in Fig. 5. In other words, the wings
153 and 154 serve as a guiding rail to guide downward
movements of the toothed member 14, thereby disengaging
the toothed member 14 from the ratchet wheel 20. The
spring force provided by the spring 16 is now able to
push the toothed member 14 back to its initial position
shown in Fig. 3. Thus, the ratchet-type ring spanner may
function as usual even if alien objects enter. The alien
objects may be removed periodically or immediately after
finish of repair.
A further embodiment of the invention is shown in
Fig . 8 . As in the embodiment of Fig . 2 , the ratchet
wheel 20 includes a plurality of teeth 21 in an outer
periphery thereof and an inner periphery for engaging
with sides of a nut or the like. In Fig. 8, however, the
ratchet wheel 20 includes a concave outer peripheral
surface having a plurality of teeth 21 uniformly formed
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therein and spaced apart from each other such that the
teeth 21 include a concave and curved configuration. An
arcuate toothed member 14, or pawl, is mounted in the
cavity 13 and includes a stub 141 formed on one end
thereof and a plurality of teeth 142 defined on a first
side for engaging with the teeth 21 of the ratchet wheel
20. The teeth 142 include a convex and curved
configuration for engaging with the curved and concave
teeth 21 of the ratchet wheel 20. Accordingly, the
ratchet wrench in accordance with the embodiment shown in
Fig. 8 includes a ratchet wheel and pawl having a number
of curved teeth engaged with each other so as to increase
the strength of the engagement between the teeth. Also
mounted in the cavity 13 is a stop member which is a
resilient plate 15 including two protrusions 151 and 152
formed on a first end thereof and a substantially
U-shaped anchor 155 formed on a second end thereof and
received in the depression 131. The resilient plate 15
further includes a post 156 extending outwardly from a
mediate portion of a side thereof and a pair of wings 153
and 154 respectively extending outwardly from mediate
portions of two longitudinal edges thereof in a plane
substantially perpendicular to a longitudinal direction
thereof .
Although the invention has been explained in
relation to its preferred embodiments, it is to be
understood that many other possible modifications and
variations can be made without departing from the spirit
and scope of the invention as hereinafter claimed.
