CA2227455A1

CA2227455A1 - Plug

Info

Publication number: CA2227455A1
Application number: CA002227455A
Authority: CA
Inventors: Hitomi Sonomoto
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-03-31
Filing date: 1998-01-20
Publication date: 1998-09-30
Also published as: CN1195212A; EP0869582A3; KR19980079936A; EP0869582A2

Abstract

A plug to be connected with a socket is disclosed. The plug includes a plug terminal to be inserted into and connected with a socket, an anti-disconnection member provided to the plug terminal, and a switch mechanism for switching over between a first position where the anti-disconnection member is retracted within the plug terminal and a second position where the anti-disconnection member is projected out of the plug terminal.

Description

CA 022274~ 1998-01-20 PLUG

BACKGROUND OF THE INVENTION

1. ~IELD OF THE INVENTION

The present invention re]ates to a plug to be connected with a socket.

2. DESCRIPTION OF THE RELATED ART

In case the plug to which this invention pertains is an electric plug, it sometimes happens that the electric plug is inadvertently disconnected from an electric outlet socket e.g. when a cord connected with the plug is strongly pulled by being hooked by a foot of a person who has accidentally tripped over the cord. The disconnection results in power failure which in turn causes various problems iIl the electric appliances which were connected to the socket. For instance, if the appliance incorporates a timer, an error will result in a time set on this timer. In the case of a temperature controller for controlling water temperature in a tank for tropical fish kept therein, the failure may lead to killing of the fish. Or, in the case of a computer, this may result in total destruction of data being processed on the computer.
In order to cope with this problem, some electric appliances are provided with power-failure protection means such as a backup battery incorporated therein for avoiding sudden stop of electricity supply.
However, due to ~ignific~nt cost burden therefrom, use of such protection means has been limited to rather expensive appliances, hardly used in less expensive appliances widely used in domestic and business environment.
The present invention attends to the above-described state of the CA 022274~ 1998-01-20 art and its primary object is to propose more economical, yet effective means for avoiding inconveniences resulting from a power failure by providing an electric plug which can effectively resist accidental disconnection thereof from an electric socket such as a common AC wall outlet.

SUMMARY OF THE INVENTION

For accomplishing the above-noted object, a plug, according to the present invention, comprises:
a plug terminal to be inserl;ed into and connected with a socket;
an anti-disconnection member provided to the plug terminal; and a switch me(~h~qni~m for swit~hing over between a first position where the anti-disconnection member is retracted within the plug terminal and a second position where the anti-disconnection member is projected out 16 oftheplugterminal.
With the above construction, the anti-disconnection member is normally retracted and kept inside the plug terminal. When the plug is connected with the socket, the switch mech~ni~m is operated to bring the anti-disconnection member into the second position where this member is 20 projected out of the terminal. Then, the projection of the anti-disconnectioneffectively resists inadvertent dis~onnection of the plug from the socket when the plug is accidentally pulled therefrom.
Preferably, the plug includes a plurality of said second positions.
The mating socket may come in a variety of inner constructions.
26 Then, the above feature may provide the plug with adaptability for such varied constructions.
According to another preferred feature of the invention, the plug includes a pair of said plug terminals and a corresponding pair of anti-disconnection members; and the switch me~h~ni~m includes a single drive 30 member for commonly driving the pair of anti-disconnection members.

CA 022274~ 1998-01-20 The use of one common drive member, rather than two members, allows reduction in the number of components, hence, the cost of the plug.
Incidentally, the plug of the invention may be any kind of plug, not limited to any specific electric plug of some particular electric appliance.
According to a still further feature of the invention, the plug further comprises an urging member for urging the anti-disconnection member from the second position to the first position; the anti-disconnection member includes a guide portion for guiding the movement of the anti-disconnection member from the second position to the first position when the anti-disconnection member is forcibly driven from the second position to the first position; and the anti-disconnection member is switched over to the second position upon completion of insertion of the plug into the socket.
In the case of the above construction, the anti-disconnection member is normally kept at the second position where the member projects out of the plug terminal. Then, as the plug is inserted into the socket, the anti-disconnection member is forcibly moved from this second projecting position to the first retracted position. Thereafter, when the plug has been completely inserted into the socket, the anti-disconnection member is automatically returned to the second position from the first position by the urging force of the urging member.
Therefore, if the plug is provided with the above construction, a user may insert this plug into the socket in the same manner as the conventional plug without the anti-disconnection member. Then, the invention has achieved the useful plug having the anti-disconnection function without losing the convenience of the conventional plugs having no such function.
The urging member may be constructed in a variety of manners.
For instance, the member may be constructed from a wire. The wire member has the advantages of readiness of manufacture and possibility of the member being readily disposed within such a limited space as the inside CA 022274~ 1998-01-20 of the plug terminal.
According to a still further feature of the invention, the plug includes a pair of said plug terminals and a corresponding pair of said anti-disconnection members; and the second positions of these members are arranged such that they are projected in direction opposed to each other.
In the case of some known types of sockets, they are to be inserted while being turned. Then, when such plug is inserted into the socket, the plug may be inadvertently disconnected from the socket, if the anti-disconnection members are projected in a same direction.
However, if the anti-disconnection members are caused to project in the direction opposite to each other, as so proposed by the present invention, it may be assured that either one of the members may reliably stay engaged with the socket. Therefore, with this construction, the plug may provide its effect in such special case also.
According to one preferred embodiment, the anti-disconnection member is constructed as a lever pivotable about a pivot axis provided in the plug terminal. For disconnecting the plug from the socket, a manipulator member provided to a cover of the plug is manipulated for moving the anti-disconnection member from the second projecting position to the first retracted position. In doing this, the presence of the pivot in theplug terminal may render the operation more smooth and easier.

BRIEF DESCRIPTION OF THE DRAVVINGS

Further and other features and objects of the invention will become apparent from the following detailed disclosure of preferred embodiments in conjunction with accompanying drawings, in which;
Fig. 1 is a perspective view showing an entire electric plug relating to a first preferred embodiment of the invention, with (a) showing a condition when anti-disconnection levers are retracted and (b) showing a CA 022274~ 1998-01-20 further condition when the anti-disconnection levers are projected, respectively, Fig. 2 is a plan view showing a switch meçhz~ni~m relating to the first embodiment, Fig. 3 is a side view showing the switch mechanism relating to the first embodiment, Fig. 4 is a section view showing a condition when the plug of the first embodiment is connected with a socket, Fig. 5 is a section view showing a further condition when the plug of the first embodiment is connected with the socket, Fig. 6 is an exploded perspective view showing plug terminals relating to the first embodiment, Fig. 7 is a perspective view showing an entire electric plug relating to a second embodiment of the invention, Fig. 8 is a side view showing a switch mech~ni~m relating to the second embodiment, Fig. 9 is a plan view showing the switch me~h?~ni.~m relating to the second embodiment, Fig. 10 is a perspective view showing an entire electric plug relating to a third preferred embodiment of the invention, with (a) showing a condition when anti-disconnection levers are retracted and (b) showing a further condition when the anti-disconnection levers are projected, respectively, Fig. 11 is a section view showing a switch me~h~ni.cm relating to the third embodiment, with (a) showing a condition when a push button is depressed to retract the anti-disconnection levers and (b) showing a further condition when the push button is released to project the anti-disconnection levers, Fig. 12 is an exploded perspective view showing plug terminals relating to the third embodiment, and CA 022274~ 1998-01-20 Fig. 13 is a view illustrating a process for inserting the plug of the third embodiment into the socket.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[first embodiment]

A first preferred embodiment of the present invention will now be detailed with reference to Figs. 1 through 6.
An electric plug 1 includes a pair of plug terminals 2a, 2b, covers 3, 4, a screw 5 for fixedly connecting the covers 3, 4 together, and a cord 6.
As shown in Fig. 6, the plug terminals 2 include outer elements 20, 21, and an intermediate element 22 interposed between the outer elements 20, 21. The intermediate element 22 defines a cutout 22a for forming a space A in which an anti-disconnection me~h~ni.~m is to be attached.
These element, i.e. the outer elements 20, 21 and the intermediate element 22 are connected together by any known appropriate method such as welding, bonding or the like. In the space A, there is attached an anti-disconnection lever 11 ('an anti-disconnection member') which is pivotable about a shaft 12. The shaft 12 is attached to the outer elements 20, 21 by any appropriate method such as welding, caulking or the like. This anti-disconnection lever 11 includes a serrated portion 11a for coming into contact with the inside of the socket for providing an anti-disconnection function for the plug connected thereto and a gear-teeth portion 11b for meshing with a rack portion 10a of a drive member 10. The serrated portion 11a is shaped such that each tooth thereof forms an angle H =45 degrees, as shown in Fig. 3.
Further, to the cover 3, there is mounted a manipulator lever 8 which is slidable along an axis Y-Y in Fig. 3 for activating the anti-disconnection lever 11 via the drive member 10. The manipulator lever 8 CA 022274~ 1998-01-20 includes a control portion 8a to be manipulated by a user's finger and a pressing portion 8b for driving the drive member 10. A spring 9 is provided for biasing the manipulator lever 8 in the upward direction in Fig. 8 This spring 9 has one leg thereof supported by a connecting portion lOb of the 5 drive member 10 and the other leg thereof supported by a fixing portion 3a of the cover 3.
The drive member 10 includes a pair of rack portions 10a in correspondence with a pair of plug terminals 2a, 2b and an interconnecting portion 10b for interconnecting these rack portions 10a. Then, by driving 10 the drive member 10 in the downward direction in Fig. 2, the pair of right and left anti-disconnection levers 11 may be driven simultaneously. The drive member is formed of non-conductive material such as synthetic resin, in order to avoid short-circuit.
The manipulator lever 8 is pivotable about the axis Y-Y in Fig. 2.
15 For operating this lever 8, the control portion 8a will be pivotally raised by the finger and then this portion 8a is pressed downwards. The cover 3 defines a slot 7 for guiding the manipulator lever 8. And, this slot 7 includes a plurality of hol(ling portions 7a, 7b, 7c at each of which the control portion 8a may be stably held in position. By selectively hokling 20 the control portion at one of the holding portions 7a, 7b, 7c, the pivotal amount of the anti-disconnection lever, i.e. the projecting amount thereof from the plug terminal 2, may be varied.
The position where the control portion 8a is held at the holding portion 7a corresponds to 'a first position' and the position where the portion 25 8a is held at the hol(ling portion 8b or 8c corresponds to 'a second position', respectively.

(description of operation) Next, the operation of the above-described plug relating to the first CA 022274~ 1998-01-20 embodiment will be described.
First, the plug 1 is inserted into a socket 13; then, the manipulator lever 8 is operated for ret~ining the control portion 8a thereof at either the portion 7b or 7c. Which of these portions 7b, 7c the portion 8a is to be held 5 will be determined, depending on the particular inner construction of the socket 13. When the control portion 8a is held at the holding portion 7c, the anti-disconnection levers 11 are pivoted through 90 degrees approximately, thus subst~nti~lly forming 90 degrees relative to the respective plug terminals 2, as shown in Fig. 4.
Conversely, for disconnecting the plug 1 from the socket 13, this becomes possible after returning the anti-disconnection levers 11 from the condition of Fig. 4 to the condition of Fig. 3. Specifically, the manipulator lever 8 is operated so as to allow the control portion 8a to exit the hollling portion 7c. Upon this, by means of the biasing force of the spring 9, the 15 manipulator lever 8 will be autom~tic~lly returned to its original position so as to bring its control portion 8a to the position of the holding position 7a.
Thereafter, in order to complete this disconnecting operation, the manipulator lever 8 is operated again so as to allow the control portion 8a to be held at the holding portion 7a in the stable manner.
[second embodiment]

A second embodiment of the invention will be described next with reference to Figs. 7 through 9. Fig. 7 shows an outer appearance of a plug 25 relating to this second embodiment, with (a) showing the plug as viewed from the side of its plug terminals and (b) being a plan view showing cases from above. Fig. 8 is a side view of a switch me~h~ni~m relating to this second embodiment, and Fig. 9 is a plan view of the switch me~h~ni~m The components employed in this embodiment and functioning similarly to 30 those employed in the first embodiment are denoted with like reference CA 022274~ 1998-01-20 marks or numerals.
This plug 1 ~ ers in its outer appearance from that of the first embodiment in that the cord 6 and the plug terminals 2 extend normal to each other and in correspondence therewith the covers 3, 4 have a different 5 shape than those of the first embodiment. As shown in Figs. 8 and 9, the cover 3 defines a through hole 3a through which a manipulator knob 14 extends. This manipulator knob 14 includes a female thread portion 14b which is threaded with a male thread portion formed on the interconnecting portion 10b of the drive member 10.
Then, after inserting this plug 10 into the socket, as the manipulator knob 14 is progressively turned, the threading action of this knob moves he drive member 10 to the left side in Fig. 8 thereby causing the anti-disconnection levers 11 to project from the respective plug terminals 2.
Conversely, for disconnecting the plug 1 from the socket, the manipulator 15 knob 14 is reversely turned to cause the anti-disconnection levers 11 to be accommodated within the respective plug terminals 2.
Some of modified constructions of the above-described embodiments will be described nexl,.
In the first embodiment, the specific number of the holding portions 20 provided in the slot 7 is not limited to that described in the embodiment.
The number may be decreased or increased, depending on the convenience.
In the first and second embodiments, the shape of the portion of the anti-disconnection lever 11 which portion comes into engagement with the inside of the socket is not limited to the serrated shape, but may vary in any 25 other manner as long as such shape provides the function of inhibiting inadvertent disconnection of the plug from the socket.

[third embodiment]

A third embodiment of the invention will be described next, with CA 022274~ 1998-01-20 reference to Figs. 10 through 13. Fig. 10 shows an entire outer appearance of a plug relating to this embodiment, with (a) showing a condition of the plug when a press button 32 has been depressed to allow accommodation of the anti-disconnection levers, (b) showing a further condition when the 5 button has been released to allow projection of the anti-disconnection levers.Fig. 11 shows a switch me~h~ni.qm, with (a) showing the me~h~niqm in section after completion of insertion of the plug into the socket, (b) illustrating a process of inserting the plug into the socket, respectively. Fig.12 is a plan view of the plug, and Fig. 13 is an exploded perspective view of 10 plug terminals.
The plug 1 includes a pair of plug terminals 41, 42, covers 3, 4, and a screw 5 for interconnecting the covers 3, 4, a cord 6 and anti-disconnection levers 30, 31 as the anti-disconnection members.
The anti-disconnection levers 30, 31 are provided for the respective plug terminals 41, 42. And, as may be apparent from Fig. 10, these levers 30, 31 are adapted to project in opposite directions from the end faces of the respective plug terminals 41, 42.
Figs. 11 through 13 show t;he switch me~h~ni.qm in greater details.
Although the anti-disconnection levers 30, 31 project in the opposite 20 directions from each other as described above, these levers are identical in the function. Thus, only one of them will be detailed.
The plug terminal 41 is comprised essentially of a first terminal member 43 and a second terminal member 44, with these members being connected with each other via an appropriate method such as welding. The 25 first terminal member 43 defines a space 41c for accommodating the anti-disconnection lever 30 and a spring 36 which functions as a biasing element. Further, to these respective members 43, 44, there are integrally formed dowel-like support shafts 41a, 41b for pivotally supporting the anti-disconnection levers 30. Preferably, the first terminal member 43 is 30 formed by die-casting, while the second terminal member 44 is formed by CA 022274~ 1998-01-20 press.
The anti-disconnection lever 30 will be described in greater details with reference to Fig. 1. This lever 30 includes a shaft bore 30a in which the support shaft 41a, 41b is fitted, a guide portion 30b to be pressed into 5 the hole of the socket when the plug 1 is inserted into the socket for causingthe anti-disconnection lever 30 about the pivot shaft 41a, 41b, a stopper face 30c functioning to prevent disconnection of the plug 1 upon completion of the insertion of the plug 1 into the socket, an operating surface on which the wire spring 35 acts, and a press-but;ton operating face 30e against which the 10 press button 32 is depressed.
As the pivot shafts 41a, 41b are disposed inside the plug terminals 41, 42 away from the position of the press button 32, the press bottom 32 may be operated with good feel.
The guide portion 30b has an inclination of 30 to 43 degrees 15 approximately relative to the longil;udinal direction of the plug terminal 41, such that this guide portion forces the anti-disconnection lever 30 when the plug 1 is inserted into the socket. Preferably, the wire spring 35 is formed by cutting a wire material such as a piano wire. This wire spring may have any appropriately selected cross section, such as of circular, rectangular 20 shape or the like.
The press button 32 includes a press portion 32a to be depressed by a finger or a thumb and a press seat 32b which acts on the button operating face 30e of the anti-disconnection lever 30. As shown in Fig. 12, the center of the press button 32 is offset from the anti-disconnection lever 30, so that 25 the press seat 32b has an oval shape. Further, as shown in Fig. 11, since the two anti-disconnection levers 30, 31 project in the opposite directions, another press button 33 is provided on the other opposite side.

(function of the construction of third embodiment) CA 022274~ 1998-01-20 Next, the function of this plug 1 when it is inserted into the socket will be described.
As illustrated in Fig. ll(b), when this plug 1 is inserted into the socket in the same manner as the conventional plug, an end face lla of the 5 hole of the socket 11 presses the guide portions 30b of the pair of anti-disconnection levers 30, 31, whereby the anti-disconnection levers 30, 31 are forcibly pivoted against the biasing force of the wire springs 36, that is, the anti-disconnection levers 30, 31 are moved from the projecting position toward the storage position. Accordingly, when the plug is inserted into 10 the socket, it is not necessary to depress the press buttons 32, 33.
As shown in Fig. ll(a), upon completion of the insertion of the plug 1, the guide portions 30b are released from the end face lla, so that the anti-disconnection levers 30, 31 are returned to the respective projecting positions by the biasing force of the wire springs 35, whereby the stopper 15 faces 30c are retained to a back face llb of the socket 11. As a result, the plug 1 is prevented from being inadvertently disconnected from the socket 11.

Although the present invention has been described with reference 20 some particular embodiments, it is to be understood that these embodiments are merely illustrative of the application of the principles of the invention. Numerous modifications may be made therein and other arrangements may be devised without departing from the spirit and scope of the invention.

Claims

What is claimed is:

1. A plug comprising:
a plug terminal to be inserted into and connected with a socket;
an anti-disconnection member provided to the plug terminal; and a switch mechanism for switching over between a first position where the anti-disconnection member is retracted within the plug terminal and a second position where the anti-disconnection member is projected out of the plug terminal.

2. The plug according to claim 1, wherein the plug includes a plurality of said second positions.

3. The plug according to claim 1, wherein the plug includes a pair of said plug terminals and a corresponding pair of anti-disconnection members; and the switch mechanism includes a single drive member for commonly driving the pair of anti-disconnection members simultaneously.

4. The plug according to claim 1, wherein the anti-disconnection member is pivotally supported to the plug terminal.

5. The plug according to claim 1, further comprising:
an urging member for urging the anti-disconnection member from the second position to the first position; the anti-disconnection member including a guide portion for guiding the movement of the anti-disconnection member from the second position to the first position when the anti-disconnection member is forcibly driven from the second position to the first position; and the anti-disconnection member being switched over to the second position upon completion of insertion of the plug into the socket.

6. The plug according to claim 6, wherein the urging member is a wire member.

7. The plug according to claim 5, wherein the plug includes a pair of said plug terminals and a corresponding pair of said anti-disconnection members; and the second positions of these members are arranged such that they are projected in direction opposed to each other.

8. The plug according to claim 5, wherein the anti-disconnection member is constructed as a lever pivotable about a pivot axis provided in the plug terminal.