WO2015117140A1

WO2015117140A1 - Electrical connector with foldable prongs

Info

Publication number: WO2015117140A1
Application number: PCT/US2015/014289
Authority: WO
Inventors: Mo Yuan WEN; Mui Lian Jessica TOH
Original assignee: Volex Plc
Priority date: 2014-02-03
Filing date: 2015-02-03
Publication date: 2015-08-06

Abstract

An electrical connector includes foldable live, neutral and earth prongs, each capable of rotating between a working position and a storage position about shafts, a prong bridge for coaxially connecting the shafts of the live prong and the neutral prong, a first cam and a lifting member fixed to the prong bridge, the lifting member lifting the earth prong up when the live and neutral prongs are rotated towards the working positions, a first resilient block for exerting a spring force on the first cam when the live and neutral prongs rotate, a second cam fixed to the shaft of the earth prong, and a second resilient block exerting a spring force on the second cam when the earth prong rotates.

Description

ELECTRICAL CONNECTOR WITH FOLD ABLE PRONGS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 61/935,198, filed 3 February 2014, the contents of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to an electrical connector, and more particularly to an electrical connector including foldable prongs which can rotate between a working position and a storage position.

BACKGROUND

[0003] Electronic devices, and specifically portable electronic devices such as mobile phones, personal digital assistants (PDAs), digital still cameras, digital video cameras, notebook computers, and the like, have built-in batteries. If no external power supply apparatus is provided to power the electronic device, the built-in battery is usually used as the main power source. If the power supplied from the battery is insufficient, the user may plug into the electronic device an electrical connector of a power supply apparatus, such as a power adapter, to provide power for operating the electronic device and for charging the battery.

SUMMARY

[0004] An electrical connector according to embodiments of the present disclosure comprises a connector for connecting to a power adapter or directly connecting to an electrical device and an electrical plug for connecting to a main supply. The connector includes a live terminal, a neutral terminal, and an earth terminal. The electrical plug includes a housing comprising a housing cover and a housing base, a live prong capable of rotating between a working position and a storage position and being electrically connected to the live terminal, a neutral prong capable of rotating between a working position and a storage position and being electrically connected to the neutral terminal, an earth prong capable of rotating between a working position and a storage position and being electrically connected to the earth terminal, and a lifting member capable of lifting the earth prong up when the live prong and the neutral prong rotate towards their working positions. The electrical connector of the present disclosure further comprises a first cam, a first resilient block configured to exert a spring force on the first cam upon engagement so as to facilitate the live prong and the neutral prong to rotate between their working positions and their storage positions and maintain the live prong and the neutral prong in their working positions or their storage positions. A second cam and a second resilient block are also provided and configured to exert a spring force on the second cam so as to facilitate the earth prong's rotation from a working position and a storage position and to maintain the earth prong in the working position or the storage position.

[0005] An electrical plug according to embodiments of the present disclosure comprises a live prong capable of rotating between a working position and a storage position along a first shaft, a neutral prong capable of rotating between a working position and a storage position along a second shaft, an earth prong capable of rotating between a working position and a storage position along a third shaft, a housing including a housing base and a housing cover. The housing comprises a first receptacle for storing the live prong, a second receptacle for storing the neutral prong, and a third receptacle for storing the earth prong, a prong bridge for connecting the live prong to the neutral prong that is capable of coaxially rotating with the first shaft and the second shaft, a first cam being fixed to the prong bridge, a lifting member which is fixed to the first cam and is capable of lifting the earth prong up when the live prong and the neutral prong rotate towards the working positions, a first resilient block configured to exert a spring force on the first cam upon engagement so as to facilitate the live prong and the neutral prong to rotate between their working positions and their storage positions and to maintain them in their working positions or their storage positions, a second cam being fixed to the third shaft, a second resilient block configured to exert a spring force on the second cam upon engagement so as to facilitate the earth prong to rotate between its working position and its storage position and maintain it in the working position or the storage position.

[0006] An electrical connector according to the present disclosure is safe and convenient to the user. A lifting member performs a critical safety function to prevent an earth prong from being absent from its working position. Once a live prong and a neutral prong rotate towards perpendicular working positions, a lifting member will lift an earth prong up and cause it to rotate towards its working position as well, thereby preventing the live prong and the neutral prong from being inserted into a socket without the earth prong also being inserted. Meanwhile, a live prong, a neutral prong, and an earth prong may easily and smoothly rotate between working positions and storage positions. A first resilient block or a second resilient block is configured to exert a spring force on a corresponding cam upon engagement so as to facilitate corresponding prong(s) to rotate between a working position and a storage position. In addition, a spring force exerted on a first cam or a second cam by a corresponding resilient block may help corresponding prong(s) be stably maintained in a working position or storage position. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 illustrates an embodiment of an electrical connector and a corresponding power adapter;

[0008] FIG. 2 is an exploded perspective view showing an electrical connector;

[0009] FIGS. 3 A and 3B illustrate an electrical connector with foldable prongs in their working positions and storage positions, respectively;

[0010] FIG. 4 illustrates a live or neutral prong with a corresponding first or second shaft;

[0011] FIG. 5 illustrates a live prong and a neutral prong being connected together by a prong bridge;

[0012] FIG. 6A, 6B and 6C illustrate a live prong and a neutral prong being connected to a corresponding live or neutral terminal by a corresponding connecting member;

[0013] FIG. 7 illustrates an earth prong with a third shaft;

[0014] FIGS. 8A and 8B illustrate an earth prong being connected to an earth terminal by a third connecting member;

[0015] FIG. 9 illustrates an earth prong being disconnected from a third connecting member;

[0016] FIGS. 10A and 10B illustrate a live prong, a neutral prong, or an earth prong being supported by a corresponding holder;

[0017] FIGS. 11 A and 1 IB illustrate foldable prongs rotating from storage positions to working positions; and

[0018] FIGS. 12A and 12B illustrate foldable prongs rotating from working positions to storage positions.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0019] FIG. 1 illustrates an embodiment of an electrical connector 100 interfacing with a rectangular power adapter 101. The electrical connector 100 comprises an electrical plug 102 and a connector 104 contained by a housing 103. The adapter 101 is presented for illustration purposes. It is noted that a power adapter need not be shaped or resemble the adapter 101 shown in FIG. 1. Regardless of the shape of the adaptor 101, the adapter 101 at least includes an inlet 105 (not fully shown) of a known type for connecting with the connector of the electrical connector 100. In the present illustration, the connector 104 is a C5 connector and the inlet of the adapter 101 is a C6 inlet, but any type of connector and inlet could be utilized. The power adapter 101 operates as a power supply, which may or may not include a transformer or other means of converting different voltages and currents of the AC power provided by a main power source (not shown) to DC power required by an electronic device (not shown) connected to plug 102. Many modern power supplies are switched mode supplies capable of converting 110-240 V AC power from a main supply to several output DC voltages and would therefore work with a range of different connectors and inlets. In addition, if the electrical device includes a built in power adapter and does not make use of adapter 101, the electrical device itself could include an appropriate inlet, such as a C6 inlet, so that the electrical connector 100 could be connected directly to the C6 inlet of the electrical device.

[0020] As noted, electrical connector as disclosed herein can use plugs of any voltage standard and plugs supporting two or more voltage standards. The electrical connector can also use plugs of any shape, size, and type. For example, FIGS. 1-12 illustrate an electrical connector 100 with a type B plug used in North America. As noted, alternative embodiments can be used with any other suitable earthed plugs which include an earth prong typically extending further than a live prong and a neutral prong to ensure that it is engaged first and that the electrical device is earthed prior to the connections by the live prong and the neutral prong.

[0021] FIG. 2 depicts an exploded view of the electrical connector 100 according to the present disclosure. The electrical connector 100 includes a housing cover 105, a live prong 106, a neutral prong 108, an earth prong 110, support members 202, a live terminal 130, a neutral terminal 132, an earth terminal 134, and a housing base 160. The housing cover 105, support members 202, and the housing base 160 may be made of any suitable insulation materials, such as plastics. The housing cover 105 may be connected to the housing base 160 to form the housing 103 for supporting and receiving the prongs and other relevant components. The prongs and terminals may be made of any suitable electrically conductive materials, such as copper and brass. The prongs 106, 108, and 110 may be electrically coupled to the terminals 130, 132, and 134, respectively. The terminals 130, 132, and 134 may be fixed in the connector 104.

[0022] The live prong 106, the neutral prong 108, and the earth prong 110 can rotate within the support members 202 between their perpendicular working positions and their horizontal storage positions. As shown in FIG. 3 A, the prongs 106, 108, and 1 10 are in their working positions when they are perpendicular to the top surface of the housing cover 105. As shown in FIG. 3B, each of the prongs 106, 108, and 110 can rotate to fold down into a corresponding receptacle formed in the housing cover 105 for storage when they are not being used. [0023] As shown in FIGS. 3A and 3B, the housing cover 105 includes a first receptacle 107 for storing the live prong 106, a second receptacle 109 for storing the neutral prong 108, a third receptacle 111 for storing the earth prong 110. The housing cover 105 also includes a first side wall 123 and a second side wall 125. The first side wall 123 may be opposite to and parallel with the second side wall 125. The three receptacles 107, 109, and 111 may be positioned in parallel. The receptacles 107, 109, and 111 may be three narrow channels extending from the top surface of the housing cover 105 downwards to a certain depth so as to fully receive the corresponding prongs when they are in their horizontal storage positions. The receptacles 107, 109, and 111 include a first, second, and third side opening 112, 113, and 115, respectively, and a first, second, and third inner side surface 120, 121, and 122, respectively. The first side opening 112 of the first receptacle 107 and the second side opening 113 of the second receptacle 109 may be formed in the first side wall 123. The third side opening 115 of the third receptacle 111 may be formed in the second side wall 125. The first, second, and third inner side surface 120, 121, and 122 also form the receptacles 107, 109, and 111 and may work as stop block, for stopping the corresponding prong's rotation when it reaches the perpendicular working position.

[0024] As shown in FIGS. 4 and 5, a first shaft 114 may be electrically connected and attached to one end of the live prong 106 such that the live prong 106 may rotate about the first shaft 114. A second shaft 116 may be electrically connected and attached to one end of the neutral prong 108 such that the neutral prong 108 may rotate about the second shaft 116. The first shaft 114 and the second shaft 116 may be made of any suitable electrically conductive material, such as copper. The live prong 106 with the first shaft 114 and the neutral prong 108 with the second shaft 116 may be physically connected together by a prong bridge 118, as shown in FIG. 5. Each end of the prong bridge 118 may be coaxially coupled to the first shaft 114 or the second shaft 116. The prong bridge 118 may be made of any suitable insulation material so as to electrically isolate the first shaft 114 from the second shaft 116. A first cam 150 may be fixed approximately at the middle portion of the prong bridge 118. Detailed structure and function of the first cam 150 will be described below.

[0025] As shown in FIGS. 6 A, 6B, and 6C, a first connecting member 136 and a second connecting member 138 are provided for electrically connecting the live prong 106 to the live terminal 130 and for electrically connecting the neutral prong 108 to the neutral terminal 132, respectively. The connecting members 136 and 138 may be made of any suitable electrically conductive materials, such as copper or brass. Each connecting member 136 or 138 and the corresponding terminal 130 or 132 may be formed of one piece of electrical conductive material.

Optionally, each connecting member 136 or 138 may be formed separately and then be attached to the corresponding terminal 130 or 132 by any suitable methods, such as welding. The first connecting member 136 and the second connecting member 138 may have substantially the same shape and dimension. One of the connecting members, e.g., the first connecting member 136, is taken as an example to illustrate part of its detailed structure, as shown in FIG. 6C. The portion of the first connecting member 136 connecting to the first shaft 114 may be a U-shaped resilient piece formed by a pair of continuous engaging elements 137a and 137b which are capable of being engaged with the first shaft 114 so as to accomplish electrical connection between the live prong 106 and the live terminal 130. Preferably, the pair of continuous engaging elements 137a and 137b may be disposed at the middle-upper portion of the arms of the first connecting member 136.

[0026] As shown in FIG. 7, a third shaft 117 may be attached to one end of the earth prong 110 by any suitable methods, such as by molding. The earth prong 110 may rotate about the third shaft 117. The third shaft 117 includes a pair of rotating elements 119a and 119b, which are disposed at the opposite sides of the earth prong 110 and more particularly shown in FIG. 8B. The rotating elements 119a and 119b may work as the rotation axis of the earth prong 110. The third shaft 117 may be made of any suitable insulation materials. A second cam 152 may be fixed to the third shaft 117 and positioned between the two rotating elements 119a and 119b, more particularly shown in FIG.9. Preferably, the second cam 152 and the third shaft 117 may be formed of one piece of insulation material. Detailed structure and function of the second cam 152 will be described below.

[0027] As shown in FIGS. 8A and 8B, a third connecting member 139 may be provided for electrically connecting the earth prong 110 to the earth terminal 134 while the earth prong 110 is in its working position. The third connecting member 139 may be made of any suitable electrically conductive materials, such as copper or brass. The third connecting member 139 and the earth terminal 134 may be formed of one piece of electrical conductive material. Optionally, the third connecting member 139 may be formed separately and then be fixed to the earth terminal 134 by any suitable method, such as soldering or welding. The third connecting member 139 may be a U-shaped piece and includes a side opening 141. When the earth prong 110 is in its perpendicular working position, the bottom end of the earth prong 110 may be fully received in the U-shaped third connecting member 139 so as to accomplish electrical connection between the earth prong 110 and the earth terminal 134.

[0028] As shown in FIG. 9, in the process of the earth prong 110 rotating from its working position to its storage position, it may move out of the third connecting member 139 through the side opening 141. When the earth prong 110 rotates to a certain position, it may be completely disconnected from the third connecting member 139, thereby being disconnected from the earth terminal 134.

[0029] As first shown in FIG. 2 by support members 202, and more particularly in FIGS. 10A and 10B, a first holder 124 and a second holder 126 may be provided for supporting the prong bridge 118 so as to further support the live prong 106 and the neutral prong 108. A pair of third holders 128a and 128b may be provided to support the rotating elements 119a and 119b of the third shaft 117, thereby supporting the earth prong 110. The first holder 124, the second holder 126, and the third holders 128a and 128b may be disposed on the inner surface of the housing base 160. The first holder 124 and the second holder 126 may be positioned at the opposite sides of the first cam 150 (not shown in FIGS. 10A and 10B). The first holder 124 or the second holder 126 includes a U-shaped receptacle for receiving the prong bridge 118. They are arranged such that the prong bridge 118 may smoothly rotate within the receptacles of the first holder 124 and the second holder 126. The third holders 128a and 128b may be disposed at the opposite sides of the earth prong 110. The third holder 128a or 128b includes a U-shaped receptacle for receiving the corresponding rotating element 119a or 119b of the third shaft 117. They are arranged such that the rotating element 119a or 119b may smoothly rotate within the corresponding receptacle of the third holder 128a or 128b. The first holder 124, the second holder 126, and the third holders 128a and 128b may be made of any suitable insulation materials.

[0030] As mentioned above and illustrated in FIGS. 11A and 1 IB, the first cam 150 may be fixed to the middle portion of the prong bridge 118; the second cam 152 may be fixed to the third shaft 117 and positioned between its two rotating elements 119a and 119b. As more particularly shown in FIGS. 11A, 1 IB, 12A, and 12B, the electrical connector 100 further includes a lifting member 151, a first resilient block 156, and a second resilient block 158. The lifting member 151 may be made of any suitable insulation material. The lifting member 151 is fixed to and substantially opposite the first cam 150. Preferably, the lifting member 151 and the first cam 150 may be formed of one piece of insulation material. The lifting member 151 may be configured and disposed such that it is capable of lifting the earth prong 110 up when the live prong 106 and the neutral prong 108 rotate towards the working positions. The lifting member

151 may be positioned below and adjacent to the earth prong 110 when the earth prong 110 is in its horizontal storage position. More particularly shown in FIG. 12B, a supporting member 153 may be provided to support the lifting member 151 so that the lifting member 151 may be in a horizontal position and substantially in parallel with the earth prong 110 when it is in its horizontal storage position. When the live prong 106 and the neutral prong 108 rotate towards their working positions, the lifting member 151 may accordingly rotate upward so as to lift the earth prong 110 up toward its working position as well.

[0031] The lifting member 151 performs a critical safety function to prevent the earth prong 110 from not being in its storage position while the live prong 106 and the neutral prong 108 are in their working positions. Once the live prong 106 and the neutral prong 108 rotate towards the working positions, rotating about the prong bridge, that rotation will also cause the lifting member 151 to move against and lift the earth prong 110 up towards its working position. This configuration also serves to prevent the live prong 106 and the neutral prong 108 from being inserted to a socket without the earth prong 110 in its working position. In reverse, the live prong 106 and the neutral prong 108 are pushed down to their storage positions, the earth prong 110 will likewise then be pushed down to its storage position.

[0032] The first resilient block 156 and the second resilient block 158 are

approximately perpendicularly fixed on the inner surface of the housing base 160. The first resilient block 156 and the second resilient block 158 may be made of any suitable resilient insulation material, such as plastic. Optionally, the first resilient block 156, the second resilient block 158, and the housing base 160 may be formed of one piece of insulation material by any suitable method, such as molding. The first resilient block 156 may be positioned between and away from the prong bridge 118 and the inner surface of the first side wall 123 of the housing cover 105, thereby allowing the first resilient block to bend to some extent away from the prong bridge when pushed by the first cam 150. The second resilient block 158 may be positioned between and away from the third shaft 117 and the inner surface of the second side wall 125 of the housing cover 105, thereby allowing the second resilient block 158 to bend to some extent away from the third shaft 117 when pushed by the second cam 152.

[0033] As noted, the first resilient block 156 may be engaged by the first cam 150 and exert a spring force against the first cam 150 that must be overcome to cause the live prong 106 and neutral prong 108 to their working positions. This spring force helps to ensure the live prong 106 and neutral prong 108 are not accidentally moved to the working position. When being moved back to their storage positions, the first resilient block 156 will exert a spring force that facilitates the live prong 106 and the neutral prong 108 rotating between the working positions and the storage positions. The second resilient block 158 may be engaged by the second cam 152 and exert a spring force on the second cam 152 when the earth prong 110 moves between the working position and the storage position. While the earth prong 110 may be moved to its working position without moving the live prong 106 or neutral prong 108, the live prong 106 and neutral prong 108 cannot be moved to their working position without also moving the earth prong 110 from its storage position.

[0034] FIGS. 11A and 1 IB illustrate the process of the foldable prongs 106 (not shown in FIGS. 11A and 1 IB), 108, and 110 rotating from their storage positions to working positions. While the prongs 106, 108, and 110 are folded down in their storage positions, the prongs are maintained in the storage positions by engagement with the resilient blocks 156 or 158 and the corresponding cams 150 or 152. In order to move the prongs 106, 108, and 110 from their storage positions to working positions, an external force is necessary to overcome the spring force exerted on the cam 150 or 152 by the corresponding resilient block 156 or 158. When the live prong 106 or the neutral prong 108 is lifted up by a user and rotated upwards along the corresponding shaft 114 or 116 towards the working position, the prong bridge 118 along with the first cam 150 may coaxially rotate. Accordingly, the lifting member 151 which is fixed to the prong bridge 118 may follow to rotate upwards in the same rotation direction as the live prong 106 and the neutral prong 108, thereby lifting the earth prong 110 up and causing the earth prong 110 to rotate along the third shaft 117 in the opposite rotation direction towards its working position.

[0035] As the prongs 106, 108, and 110 rotate towards the working positions, the first cam 150 and the second cam 152 rotate accordingly. When the first cam 150 or the second cam 152 passes a certain position, it may be pushed by the corresponding resilient block 156 or 158. The resilient blocks 156 and 158 may exert the spring force on the corresponding cams 150 and 152 to facilitate the prongs 106, 108, and 110 to rotate to the working positions. When the earth prong 110 reaches its perpendicular working position, the inner side surface 122 of the third receptacle 111 may stop the rotation of the earth prong 110. The earth prong 110 may maintain in its working position due to the engagement between the second cam 152 and the second resilient block 158. When the live prong 106 and the neutral prong 108 reach their perpendicular working positions, they may be stopped by the inner side surface 120 of the first receptacle 107 and the inner side surface 121 of the second receptacle, respectively. The live prong 106 and the neutral prong 108 may maintain in their working positions due to the engagement between the first cam 150 and the first resilient block 156.

[0036] FIGS. 12A and 12B illustrate the process of the foldable prongs 106, 108, and

110 rotating from their working positions to storage positions. In order to move the prongs 106,

108, and 110 from their working positions to their storage positions, an external force is necessary to overcome the spring force exerted on the cams 150 and 152 by the corresponding resilient blocks 156 and 158. When the prongs 106, 108, and 110 are pushed down by a user, the prongs along with the corresponding cams may begin to rotate towards the storage positions. The live prong 106 and the neutral prong 108 may rotate in the same direction; the earth prong 110 may rotate in the opposite direction, which enables the electrical connection 100 to require less physical space. When the first cam 150 or the second cam 152 passes a certain position, it may be pushed by the corresponding resilient blocks 156 or 158. The first resilient block 156 and the second resilient block 158 may provide a spring force to help the corresponding prongs to rotate to the storage positions. When the prongs 106, 108, and 110 reach the storage positions, the first cam 150 or the second cam 152 may be stopped by the bottom of the receptacles 107, 109, and 111, thereby the prongs 106, 108, and 110 are tucked away in their storage positions.

[0037] In addition to the embodiments discussed above, the present disclosure is likely to have various alterations, modifications, and improvements which will readily occur to those skilled in the art. For instance, the specific choice of materials with respect to the various components are within the ability of those skilled in the art according to the disclosure, based on the functional indications given above. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention.

Claims

What is claimed:

1. An electrical connector with foldable prongs, comprising:

a housing including a housing cover and a housing base, the housing supporting a connector for connection to an inlet and an electrical plug for connection to a main power supply, the connector including a live terminal, a neutral terminal, and an earth terminal, the electrical plug including:

a live prong configured to rotate between a first working position and a first storage position, the live prong being electrically connected to the live terminal,

a neutral prong configured to rotate between a second working position and a second storage position, the neutral prong being electrically connected to the neutral terminal,

an earth prong configured to rotate between a third working position and a third storage position, the earth prong being electrically connected to the earth terminal,

wherein the electrical connector further comprises a lifting member configured to engage and lift the earth prong up when the live prong and the neutral prong rotate toward the first working position and the second working position.

2. The electrical connector of claim 1, further comprising a first shaft electrically connected and fixedly attached to the live prong and a second shaft electrically connected and fixedly attached to the neutral prong, the live prong being configured to rotate about the first shaft and the neutral prong being configured to rotate about the second shaft.

3. The electrical connector of claim 2, wherein the first shaft is coaxially coupled to the second shaft by an insulated prong bridge such that the first shaft, the second shaft and the prong bridge rotate coaxially.

4. The electrical connector of claim 3, wherein a first cam is fixed to approximately a middle portion of the prong bridge.

5. The electrical connector of claim 4, wherein the lifting member is fixed to the prong bridge approximately opposite the first cam.

6. The electrical connector of claim 4, wherein the prong bridge, the first cam, and the lifting member are formed of one piece of material.

7. The electrical connector of claim 4, further comprising a first resilient block configured to exert a spring force against the first cam when the live prong and the neutral prong are rotated from the first storage position and the second storage position to the first working position and the second working position, and when the live prong and the neutral prong are rotated from the first working position and the second working position to the first storage position and the second storage position.

8. The electrical connector of claim 7, wherein the housing base is substantially

perpendicular to the live prong and the neutral prong when the live prong and the neutral prong are in the first working position and the second working position, and wherein the first resilient block is fixed substantially perpendicular to the housing base.

9. The electrical connector of claim 8, wherein the housing cover includes an inner surface, and wherein the first resilient block is positioned between the prong bridge and the inner surface so as to allow sufficient space for the first resilient block to bend toward the inner surface when contacted by the first cam.

10. The electrical connector of claim 2, further comprising a third shaft fixedly attached to the earth prong, the earth prong being configured to rotate about the third shaft.

11. The electrical connector of claim 10, further comprising a second cam configured to be fixed to the third shaft.

12. The electrical connector of claim 11, wherein the second cam and the third shaft are formed of one piece of material.

13. The electrical connector of claim 11, further comprising a second resilient block configured to exert a spring force against the second cam when the earth prong is rotated from the third storage position to the third working position and when the earth prong is rotated from the third working position to the third storage position.

14. The electrical connector of claim 13, wherein the housing base is substantially perpendicular to the earth prong when the earth prong is in the third working position, and wherein the second resilient block is fixed substantially perpendicular to the housing base.

15. The electrical connector of claim 14, wherein the housing cover includes an inner surface and wherein the second resilient block is positioned between the third shaft and the inner surface so as to allow sufficient space for the second resilient block to bend toward the inner surface when contacted by the second cam.

16. An electrical plug with foldable prongs, comprising:

a live prong configured to rotate between a first working position and a first storage position about a first shaft;

a neutral prong configured to rotate between a second working position and a second storage position about a second shaft;

an earth prong configured to rotate between a third working position and a third storage position about a third shaft;

a housing including a housing cover and a housing base, the housing cover comprising a first receptacle for storing the live prong in the first storage position, a second receptacle for storing the neutral prong in the second storage position, and a third receptacle for storing the earth prong in the third storage position;

a prong bridge for coaxially connecting the first shaft to the second shaft so that the first shaft, the second shaft, and the prong bridge rotate coaxially;

a first cam fixed to the prong bridge;

a lifting member fixed to the prong bridge and configured to engage and lift the earth prong up when the live prong rotates toward the first working position and the neutral prong rotates toward the second working position; and

a first resilient block configured to exert a spring force against the first cam when the live prong and the neutral prong are rotated from the first storage position and the second storage position to the first working position and the second working position, and when the live prong and the neutral prong are rotated from the first working position and the second working position to the first storage position and the second storage position.

17. The electrical plug of claim 16, wherein the housing base is substantially perpendicular to the earth prong when the live prong and the neutral prong are in the first working position and the second working position, wherein the first resilient block is fixed substantially perpendicular to the housing base, wherein the housing cover includes a first inner surface, and wherein the first resilient block is positioned between the prong bridge and the first inner surface so as to allow sufficient space for the first resilient block to bend toward the first inner surface when contacted by the first cam.

18. The electrical plug of claim 16, further comprising a second cam configured to be fixed to the third shaft and a second resilient block configured to exert a spring force against the second cam when the earth prong rotates between the third storage position and the third working position.

19. The electrical connector of claim 18, wherein the housing base is substantially perpendicular to the earth prong when the earth prong is in the third working position, wherein the second resilient block is fixed substantially perpendicular to the housing base.

20. The electrical connector of claim 19, wherein the housing cover includes a second inner surface, and wherein the second resilient block is positioned between the third shaft and the second inner surface so as to allow sufficient space for the second resilient block to bend toward the second inner surface when contacted by the second cam.