Note: Descriptions are shown in the official language in which they were submitted.
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INTEGRATED SWITCH AND CIRC lJIT
BREAKER CONSTRUCTION
BACKGROUND O~ THE INVENTION
The present invention relates to a switch and circuit breaker
10 construction such as one which is typically utilized for optionally reversingthe direction of current flow to a motor of an electric hand tool such as a
power screwdriver, an electric drill, or an electric saw, and more
particularly relates to such a switch and circu;t breaker construction which
can be compactly accomodated.
In the prior art, in such a particular case when a switch is provided
for optionally reversing the direction of current flow to a motor of an
electric hand tool such as a power screwdriver, an electric drill, or an
electric saw, and when also a circuit breaker is provided to said electric
20 hand tool for ensuring that the supply of electricity is interrupted when theamperage of electricity supply increases above a determinate level, it has
been practiced to supply said switch and said circuit breaker as a pair.
However, since in such an arrangement said switch and said circuit breaker
are arranged separately in the electric hand tool, the internal space within
25 the body of said electric hand tool is not utilized with very great efficiency,
thus causing a waste of space. This makes the job of assembling the
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electric hand tool more difficult and causes an increase in the requirement
for the size of said electric hand tool. Further, there is a concomitant
difficulty with the assembly difficulty for said electric hand tool, due to the
fact that said switch and said circuit breaker exist as two separate units.
5 And the problem of parts management is also considerable, as is the storage
requirement for such parts.
Also, as a subsidiary desideratum, a typical such swi-lch as
conventionally provided for optionally reversing the direction of current flow
10 to a motor of an electric hand tool such as a power screwdriver, an electric
drill, or an electric saw is a rotary type switch. However, such a rotary
type switch tends to be rather complicated1 incorporating a relatively large
number of component parts, and accordingly a limit upon the compactness of
the design of the switch is imposed. Therefore, the efficiency with which
15 such a switch can be accomodated in the body of the electric hand tool is
relatively poor. Further, the operation of such a reversing switch is
relatively cumbersome for the user, because a rotary motion is required.
In the case of a slide switch such as might be conceived of for use as
20 such a switch for optionally reversing the direction of current flow to a
motor of an electric hand tool such as a power screwdriver, an electric
drill, or an electric saw, typically such a slide switch is provided with
terminals which are insert molded into a switch base, and with a slider
member which slides one or more movable contact members over said
25 terminals for switching over said terminals by connecting together various
combinations thereof. However, since such a movable contact member or
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members is or are typically fixedly supported by the slider member, the
problem tends to arise that the contact surface of such a movable contact
member tends to become non uniform, and the contact thereof against the
terminals over which it slides tends to become unstable, thereby possibly
engendering poor contact and low reliability of the switch as a whole.
SUMMARY OF THE INVENTION
The inventors of the present invention have considered the various
10 problems detailed above, particularly in the case of providing a switch for
optionally reversing the direction of current flow to a motor of an electric
hand tool and of also providing a circuit breaker for said electric hand tool
motor.
Accordingly, it is the primary object of the present invention to provide
a switch and circuit breaker construction, which avoids the problems detailed
above.
It is a further object of the present invention to provide such a switch
20 and circuit breaker construction, which is integrated as a single unit.
It is a further object of the present invention to provide such a switch
and circuit breaker construction, which is compact.
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It is a further object of the present invention to provide such a switch
and circuit breaker construction, which is easily assembled to such an
electric tool.
It is a further object of the present invention to provide such a switch
and circuit breaker construction, which allows the body of such an electric
tool to be constructed as compact.
It is a further object of the present invention to provide such a switch
and circuit breaker construction, which facilitates the assembly of such an
electric tool.
It is a further object of the present invention to provide such a switch
and circuit breaker construction, which reduces problems of parts
management and storage.
It is a yet further object of the present invention to provide such a
switch and circuit breaker construction, which has a reduced number of
component parts.
It is a yet further object of the present invention to provide such a
switch and circuit breaker construction, which is convenient and easy in use.
It is a yet further object of the present invention to provide such a
switch and circuit breaker construction, which has stable con-tacting action of
a movable contact piece thereof against fixed terminals thereof.
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It is a yet further object of the present invention to provide such a
switch and circuit breaker construction, which prevents unevenness of the
contact surface of such a movable contact piece thereof against such fixed
terminals thereof.
According to the most general aspect of the present invention, -these
and other objects are attained by a switch and circuit breaker construction,
comprising: a case; a plurality of contact members, exposed within said
case for contact; a plurality of lead terminals electrically comlected to some
10 at least of said plurality of contact members, said lead terminals being
insert molded in said case and protruding out to the outside thereof; a
support member, insert molded in said case and protruding out to the outside
thereof; and: a circuit breaker with two ends, provided outside said case,
one said end of said circuit breaker being supportcd by one of said lead
15 terminals, and the other said end of said circuit breaker being supported by
said support member.
According to such a switch and circuit breaker construction as
specified above, the problems detailed above are avoided, since the switch
20 and circuit breaker construction is integrated as a single unit. Accordingly
this switch and circuit breaker construction is compact, and is easily
assembled to an electric tool as described above, such as a power
screwdriver, an electric drill, or an electric saw. This switch and circuit
breaker construction, being itself compact, thus allows the body of such an
25 electric tool to be constructed as compact, and further, since it is only oneunit rather than being two separate units as in the prior art, facilitates the
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assembly of such an electric tool, as well as reduceillg problems of parts
management and storage.
According to a particular specialization of the present invention, the
5 above described and other objects may be more particularly attained by a
switch and circuit breaker construction as described above, wherein said
contact members, which are five in number, are arranged as being thus
exposed within said case for contact in a substantially linear relationship, and
alternat ngly serve as input side and as output side contact members, with the
10 end ones and the middle one thereof serving as contact members for being
switchied between while the other two thereof serve as common contact
members, said two end contact members being electrically connected together;
and further comprising a pair of movable contact members each of which is
mounted so as to be slidable, in synchronization with the other, over a
15 corresponding one of said common contact members and the two contact
members neighboring it. In this case, there will be a distinct advantage
attained as compared to the conventional type of rotary switch, because of
reduction in the number of component parts. Further, this switch and circuit
breaker construction, which is of a slide type, will be notably convenient and
20 easy in use.
According to an alternative particular specialization of the present
invention, the above described and other objects may be more particularly
attained by a switch and circuit breaker construction as first described
2~ above, further comprising a movable contact member which is mounted so as
to be slidable over said contact members and a slidable impeller member
with a surface confronting a sur~ace of said movable contact member and
slidingly impelling it, one of said surface of said slidable impeller member
and said surface of said movable contact member being formed with a
substantially hemispherical protuberance and the o-ther thereof being formed
5 with a substantially hemispherical depression which cooperates with said
substantially hemispherical protuberance for thus coupling said slidable
impeller member and said movable contact member with regard to mutual
sliding motion thereof. In this particular switch and circuit breaker
construction, stable contacting action of said movable contact member is
10 provided against the fixed terminals. by the tilting action available by the
cooperation of said substantially hemispherical protuberance and said
substantially hemispherical depression, and unevenness of the contact surface
of such a movable contact piece thereof against such fixed terminals thereof
is positively prevented.
BRIE:F DESCRIPTION OF THE DRAWINGS
The present invention will now be described with respect to the
preferred embodiments thereof, and with reference to the illustrative
20 drawings appended hereto, which however are provided for the purposes of
explanation and exemplification only, and are not intended to be limitative of
the scope of the present invention in any way, since this scope is to be
delimited solely by the accompanying claims. With relation to the figures,
spatial terms are to be understood as referring only to the orientation on the
25 drawing paper of the illustrations of the relevant parts, unless otherwise
specified; like reference numerals, unless otherwise so specified, denote
the same parts and gaps and spaces and so on in the various figures relating
to one preferred embodiment, and like parts and gaps and spaces and so on
in the figures relating to different preferred embodiments; and:
Fig. 1 is a perspective exploded view showing the main parts of the
first preferred embodiment of the switch and circuit breaker construction of
the present invention;
Fig. 2 is a plan view of said first preferred embodiment switch and
circuit breaker construction in its assembled state;
Fig. 3 is a longitudinal sectional view taken through said first
preferred embodiment;
Fig. 4 is a perspective phantom view f rom underneath of said first
preferred embodiment;
Fig. 5 is a longitudinal sectional view, showing a slider member
included in said first preferred embodiment and two movable contact
members associated therewith;
Fig. 6 is a diagram for illustrating the operation of said first
preferred embodiment switch and circuit breaker construction, showing it in
its state in which a one movable contact member bridges between a first
lead terminal and a second lead terminal while another movable contact
mernber bridges between a third lead terminal and a fourth lead terminal,
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thus causing a motor of a hand tool to be driven in the normal or the
forward direction;
Fig. 7, similarly to Fig. 6, is another diagram for illustrating the
5 operation of said first preferred embodiment switch and circuit brealcer
construction, showing it in its state in which said one movable contact
member bridges between said second lead terminal and said third lead
terminal while said other movable contact member bridges between said
fourth lead terminal and a fifth lead terminal, thus causing said motor of
10 said hand tool to be driven in the reverse direction; and:
Fig. 8, similarly to Fig. 1 for the first preferred embodiment, is a
perspective exploded view showing the main parts of the second preferred
embodiment of the switch and circuit breaker construction of the present
15 invention.
DESCRIPTION OF T~IE }~REFER~ED
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EMBODIMENTS
The present invention will now be described with reference to the
preferred embodiments thereof, and with reference to the figures.
THE FIRST PREFERRED EMBODIMENT
Figs. 1 through 7 relate to the first preferred embodiment of the
switch and circuit breaker construction of the present invention. This
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switch is adapted for reversing the rotational direction of ~n electric hand
tool such as a power screwdriver.
Construction
In the first preferred embodiment of the switch and circuit breaker
construction of the present invention, shown in perspective exploded view in
Fig. 1, in plan view in its assembled state in ~ig. 2, in longitudinal sectionalview in Fig. 3, and in perspective phantom view from underneath in Fig. 4,
10 the reference numeral 11 denotes the base assembly of the switch as a
whole, and 12 generally denotes an circuit breaker, while the members 13
are a pair of movable contact members and 14 generally denotes a slider
member. 15 is a sheet spring and 16 is a cover, while 17 is an anti dust
protection sheet member and 18 is a knob assembly for being gripped for
1~ operation.
In more detail, the switch base assembly 11 is generally rectangular
and is formed by insert molding or a like process, with first through fifth
lead terminals l9, 20, 21, 22, and 19a and a support piece 23 being arranged
20 as molded thereinto and being held therein in a generally mutually parallel
relationship. The upper surface in the figure of this switch base assembly
11 is formed with a rectangular depression 24 for receiving the movable
contact members 13 to be described shortly, and surfaces of the lead
terminals 19, 20, 21, 22, and 19a are exposed in this specified order within
25 this rectangular depression 24 and lie substantially flush with its defining
bottom surface, so that these exposed lead terminal surfaces can make
contact with said movable contact members 13 which can slnoothly slide on
them as will be explained hereinafter. The schernatic layout of these lead
terminals 19, 20, 21, 22, and l9a as thus exposed within this rectangular
depression 24 is shown in Figs. 6 and 7. In this shown first preferred
5 embodiment of the present invention, the first lead terminal 19 and the fifth
lead terminal l9a are in fact electrically connected together although this is
not shown in Fig. 1 (it can be seen in the underneath phantom view of Fig. 4
and in Figs. 6 and 7), and are arranged as common terminals at the opposite
ends of the row of lead terminals.
The second, third, and fourth lead terminals 20, 21, and 22 are formed
with protruding portions which extend through the side towards the viewer in
Fig. 1 of the rectangular depression 24 in the switch base assembly 11 so as
to project to the outside. These projecting end portions of said second,
third, and fourth lead terminals 20. 21, and 22 are formed with C-shaped
notches denoted as 25 for having lead wires, not particularly shown, engaged
with them. On the other hand, the first lead terminal 19 e~tends through the
side away from the viewer in Fig. 1 of the rectangular depression 24 in the
switch base assembly 11 so as to project to the outside at one end of said
switch base assembly 11, and its outer free projecting end portion is then
bent upwards from the point of view of the figure and is formed with a
notch shape 26 on its upper outer edge portion. Similarly, the support piece
23 extends through the side away from the viewer in ~ig. 1 of the
rectangular depression 24 in -the switch base assembly 11 so as to project to
25 the outside at the other end of said switch base assembly 11, and its outer
free projecting end portion is then bent upwards from the point of view of
the figure and is formed with a L-shapecl notch shape or cutclway 27 on its
upper outer edge portion, To these notch shapes 26 and 27 there are
respectively connected, by soldering or the liket the terminals 28 and 29
which are provided on the opposite ends of the circuit breaker 12. And to
5 the one 29 of said terminals of said circuit breaker 12 there is connected a
lead wire 30 which leads to a motor of a hand tool (according to the
anticipated use of this first preferred embodiment) for supplying electrical
energy thereto.
An engagement projection 31a is formed at the center of one of the
short sides of the switch base assembly 11 for being engaged with an
engagement depression, not particularly shown, formed on the body of the
electric hand tool. And an engagement depression 31b is formed at the
center of the other of the short sides of said switch base assembly 11 for
15 being engaged with an engagement projection, also not particularly shown,
similarly formed on the body of the electr;c hand tool. A ridge shape 65 is
formed around this engagement depression 31b. And small projections 32 are
formed on either sides of the ridge shape 65 around the engagement
depression 31b.
As best shown in the longitudinal sectional view thereof given in Fig.
5, each of the movable contact members 13 is generally shaped as a letter
"W", and at the central portion of its upper surface (the central point of the
"W" shape) a hemispherical protuberance 33 protrudes upwards therefrom,
25 while on the other hand at the central portions of each of the "U" shapes
which make up its "W" shape a convex "U" shape 13a is defined, suitable
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for sliding upon a cooperating member, which in fact is the bottom of the
depression 24 of the switch base assembly 11 and the upper exposed surfaces
of the lead terminals which lie flush therewith. In other words, each of the
movable contact members 13 slides along said depression 24, by being pushed
5 by the slider member 14 as will be described shortly, and electrically
connects together one or another neighboring pair of the lead terminals 19,
20, 21, 22, and l9a, as will be described later and as shown in Figs. 6 and
7. In fact, one of said movable contact members 13 slides between the first
through the third lead terminals 19, 20, and 21, while on the other hand the
10 other of said movable contact members 13 slides between the third through
the fifth lead terminals 21, 22, and l9a.
Now, the slider member 14 is formed with a body, which has an upper
depression 37 and a projecting protuberance 38 on its top side, and which has
15 on its lower side a projecting portion 34 which fits into the depression 24 of
the switch base assembly 11 so as freely to slide therein while being guided
by the sides thereof. And a pair of engagement depressions 35 are formed
in this projecting portion 34 for receiving the movable contact members 13,
each of said engagement depressions 35 being formed with a hemispherical
depression 36 for receiving the hemispherical protuberance 33 of the thus
corresponding said movable contact member 13.
Thus, as the slider member 14 is slid to and fro in the depression 24,
it pushes the movable contact members 13 by the engagement of the
hemispherical protuberances 33 into the corresponding hemispherical
depressions 36, and the movable contact members 13 are thereby smoothly
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impelled to and fro to slide along the bottom surface of the rectangular
depression 24 without being adversely tilted in any particular direction or
being rocked due to torque imposed on them. This smooth pushing of the
movable contact members 13 is due to the pivoting and swinging engagement
5 of the hemispherical protuberances 33 into the hemispherical depressions 36.
Thereby the movable contact members 13 vary their electrical connections
with the lead terminals 19, 20, 21, 22, and 19a, as will be described later.
Into the depression 37 formed on the upper surface of the slider
10 member 14 there fits a sheet spring member 15, which is formed with a
hole through its central portion for passing the projecting protuberance 38.
This sheet spring member 15 is bent into the shape of a letter "V" and is
received in said depression 37 with the central point of its "Y" shape
pointing upwards. 'I`his central point of the "V" shape of the sheet spring
member 15 is formed with convex curved surfaces 40, 40 facing upwards in
the figure.
A switch cover 16 is fitted over this whole switch assembly, said
switch cover 16 being shaped like a box with an open bottom. An elongated
20 slot 42 is cut through the upper surface of said switch cover 16 for passing
the projecting protuberance 38 through, so that said projecting protuberance 38
moves to and fro along said slot 42 as the slider member 14 is reciprocated
to and fro and the movable contact members 13 are moved along over their
corresponding contacts 19 through 22 and 19a. On the inner surface of the
25 switch cover 16 in pairs adjacent to the slot 42 there are formed depressions41 (best seen in the sectional view of Fig. 3), and the convex curved
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surfaces 40, 40 of the sheet spring mernber 15 engage with a certain degree
of firmness into these depressions 41 as the slider member 14 is thus
reciprocatingly slid with the sheet spring member 15 providing biasing action
betweeen the switch cover 16 and said slider member 14 and pressing the
5 movable contact members 13 firmly against the aforesaid contacts, thus
providing a clicking or indexing action for the operation of this first
preferred embodiment of the switch and circuit breaker construction of the
present inventlon.
Contact pieces 43 formed at the four corners of the switch cover 16
near its open bottom side engage with the projections 32 of the switch base
assembly 11, so as to firmly and positively locate the switch cover 16 on the
switch base assembly 11 when it is pressed thereover and fitted thereon. At
this time, the sheet spring member 15 is somewhat compressed so as to
15 provide the biasing action described above. The projecting protuberance 38
protrudes up outwards through the slot 42 of the switch cover 16 and engages
into a hole 45 (best seen in the sectional view of Fig. 3) formed in the
lower surface of the knob assembly 18, on the reverse side of the slider
actuation knob 44. A anti dust protection sheet member 17 is provided
20 between said knob assembly 18 and the switch cover 16 and is squeezed
therebetween. Thereby the hand of a user of this first preferred
embodiment of the switch and circuit breaker construction of the present
invention may, by gripping the slider actuation knob 44 and pushing it, impel
the slider member 14, etc., to and fro as described above.
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Operatl`on
This first preferred embodiment of the switch and circuit breaker
construction of the present invention operates as will now be described.
When the knob assembly 18 is slid in the one direction, as shown in
Fig. 6 one of the movable contact members 13 bridges between the first lead
terminal 19 and the second lead terminal 20 while the other of said movable
contact members 13 bridges between the third lead terminal 21 and the fourth
10 lead terminal 22. In this condition of the apparatus, for example (according
to the particular connection of the lead terminals, etc.), electric current
flows from the second lead terminal 20 to the first lead terminal 19 on the
one hand, and from the fourth lead terminal 22 to the third lead terminal 21
on the other hand, so as to drive the motor (not shown) of this hand tool in
15 the normal or the forward direction.
On the other hand, when the knob assembly 18 is slid in the opposite
direction to said one direction, as shown in Fig. 7 said one of the movable
contact members 13 bridges between the second lead terminal 20 and the
20 third lead terminal 21 while the other of said movable contact members 13
bridges between the fourth lead terminal 22 and the fifth lead terminal 19a.
In this condition of the apparatus, again for example, electric current flows
from the second lead terminal 20 to the third lead terminal 21 on the one
hand, and from the fourth lead terminal 22 to the fifth lead terminal l9a on
25 the other hand, so as to drive the motor (not shown) of this hand tool in thereverse direction.
1 7
When due to any unusual circumstances or occurrence an elec-tric
current in excess of a determinate electrical current flows through the
circuit breaker 12, then said circuit breaker 12 responds by going open
circuit substantially immediately. Since the circuit breaker 12 is integrally
5 provided with this switching apparatus, the two of them can be mounted
together to an electric hand tool (such as a power screwdriver), in one
action simply by mounting the switch base assembly 11 of the switching
apparatus to said electric hand tool. Furthermore, the circuit breaker 12
does not require any particular extra space to be provided for it in the body
10 of the electric hand tool, thus economizing the internal space within said body
of said electrical toGl. Also the handling of the switching device and of the
circuit breaker 12 is simplified, since they are provided as one integral
assembly instead of as two separate assemblies.
It will be understood that this construction of this first preferred
embodiment of the switch and circuit breaker construction of the present
invention is very compact, as opposed to a prior art type of rotary reversing
switch: this is due to the great simplification of the contact structure as
described above. Additionally, this first preferred embodiment of the switch
20 and circuit breaker construction of the present invention can be installed in
an electric hand tool in a manner which is efficient in terms of space
requirements, and it offers simple and easy sliding operation.
Further, in this first preferred embodiment of the switch and circuit
25 breaker construction of the present invention, because the movable contact
members 13 are supported by the slider member 14 by way of the
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hemispherical protuberances 33 and the corresponding hemispherical
depressions 36 which mate therewith, the movable contact mernbers 13 are
permitted to swing to and fro about these thus defined spherical pivot
surfaces, as said movable contact members 13 slide over the contact
5 terminals. Therefore, the contacting action of the movable contact members
13 is made very even, so that said movable contact members 13 can be
ensured of making very intimate contact with the corresponding contact
terminals, thus ensuring highly stable and reliable contact action.
In fact, even when the slider member 14 is subjected to an external
force which is not directed in its direction of sliding, or the contact
surfaces of the movable contact members 13 are otherwise caused to be
uneven, since the rocking motion of the movable contact members 13 is
permitted by the pivoting action between the hemispherical protuberances 33
and the corresponding hemispherical depressions 36 which mate therewith,
thereby even and stable contact is promoted.
THE SECOND PREFERRED EMBODIMENT
The second preferred embodiment of the switch and circuit breaker
construction of the present invention is shown in Fig. 8, in a maMer similar
to Fig. 1 for the first preferred embodiment. In this figure, parts and gaps
and spaces and so on which correspond to analogous parts and gaps and
spaces and so on of the first preferred embodiment are denoted by reference
numerals like to those utilized in the figures relating to said first preferred
embodiment.
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In this second preferred embodiment, the two terminals 55 and 56 of
the circuit breaker 54 are connected to the lead terminals 52 and 53 which
extend from either end of the switch base 51, respectively, and a lead wire
connecting hole 57 is provided in the one 53 of the lead terminals for
5 directly connecting thereto the lead wire 58 for the purpose of using this one 53 of the lead terminals of the switch base assembly 51 as a supporting
member as well as a lead terminal.
The same functions and advantages are available with this second
10 preferred embodiment of the of the present invention, as were available with
the first preferred embodiment, and accordingly detailed description thereof
will be eschewed in the interests of brevity of explanation.
Although the present invention has been shown and described in terms
15 of the preferred embodiments thereof, and with reference to the appended
drawings, it should not be considered as being particularly limited thereby,
since the details of any particular embodiment, or of the drawings, could be
varied without, in many cases, departing from the ambit of the present
invention. Accordingly, the scope of the present invention is to be considered
20 as being delimited, not by any particular perhaps entirely fortuitous details of
the disclosed preferred embodiments, or of the drawings, but solely by the
scope of the accompanying claims, which follow.
