AU726114B3

AU726114B3 - An electrical plug

Info

Publication number: AU726114B3
Application number: AU35303/00A
Authority: AU
Inventors: Philip Adare Egerton
Original assignee: Pa & Jt Const Pty Ltd
Current assignee: Pa & Jt Constructions Pty Ltd
Priority date: 2000-05-12
Filing date: 2000-05-12
Publication date: 2000-11-02
Anticipated expiration: 2006-05-12
Also published as: WO2001089040A1

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A PETTY PATENT Name of Applicant: Actual Inventor: Address for Service: PA JT CONSTRUCTIONS PTY LTD PHILLIP ADARE EGERTON CULLEN CO., Patent Trade Mark Attorneys, 239 George Street, Brisbane, QId. 4000, Australia.

Invention Title: AN ELECTRICAL PLUG The following statement is a full description of this invention including the best method of performing it known to us: The present invention relates to a connecting plug for an electrical cord and in particular relates to an electrical plug assembly.

Electrical extension cords are well known. The distance from which an electrical appliance or power tool may be used- from a power source is dependant upon the length of electrical cord. Extension cords are commonly used to increase this distance. Such extension cords are widely used in association with power tools and other appliances such as hedge trimmers, blowers and the like from a power source. In use an operator may inadvertently pull in the cord and/or reach the limit of the extension cord.

When this occurs the plugs connecting the tool or appliance and cord may easily be pulled part. Separation of the connecting plugs can also commonly happen in cases where an operator of a power tool is on or climbing a ladder and the cord is being pulled upwards.

Disconnection of an appliance or tool from a power cord is inconvenient for a user. Exposure of a disconnected plug may also present an electrical hazard. Still further, if the surface upon which the cord is being used is steel or the like, a disconnected plug contacting the steel may cause an electrical short.

Some operators have been known to try to overcome this problem by tying a knot in the cords about the plugs. However, this can causes undue stress and wear and tear in the cord which can itself cause an electrical hazard. Further, it is time consuming to tie and untie the cords.

It is therefore an object of the present invention to provide an electrical plug and plug assembly which may at least partially overcome the above disadvantages or provide the public with a useful choice.

According to a first broad form of the invention there is provided an electrical plug, the plug having a body with an aperture located in a rear section thereof through which an electrical cord may pass, a connecting face having at least one pin extending therefrom or at least one recess extending therein, and a resistance zone which, when the plug is electrically connected to a second plug and the plug is pulled in the direction of a cord extending therefrom the resistance zone contacts a section of the second plug and resists separation of the second plug.

The plug of the present invention can be attached to a conventional electrical cord. The cord may be an extension cord or which one which is attached to an electrical appliance or power tool. The plug may be either a male or female-plug. A typical male plug has two or three pins extending therefrom. A female plug typically has three recesses therein. The extension cord, appliance or tool may be manufactured with a plug of the invention fitted thereto. Typically the plug is adapted such that it can easily be fitted to an existing cord after the conventional plug has been removed.

The plug has resistance zone, which, when the plug is connected to a second plug resists separation of the plugs wen pulled in the direction of the cord. Typically the second plug is also a plug of the invention, although in some cases this may not be necessary. Typically the resistance zone forms or is part of the connecting face. In some forms of the invention, the resistance zone and connecting face may be located at different locations on the plug body. When two plugs are connected the resistance zone typically abuts a section of the second plug. Where both plugs are plugs of the present invention, the resistance zones of respective plugs may abut each other.

According to a further broad from of the invention, there is provided a plug assembly comprising a male plug of the first broad from of the invention and a female plug of the first broad form of the invention.

In the plug assembly of the present invention, typically the respective plugs have complimentary contact surfaces, the resistance zone forming part of the contact surface. The contacting surfaces are typically of a shape to provide an interlocking connection between the two plugs. For example, the contacting surface may be stepped.

Typically the outer surface of the body which does not form the contacting surface, or which in use forms the exterior surface of the plug assembly, is curved or rounded. In this way the plug assembly has a rounded or curved shape. An advantage of such a shape is that it is less likely to catch on protrusions when being dragged along the surface of a work environment.

In practice such snagging has been observed to be a disadvantage with conventional plug assemblies.

When the two plugs are connected, they can typically only be separated by sliding the plugs relative to each other in the direction towards the cord of the opposite plug. The plugs may be provided with guide grooves and guide recesses to facilitate such sliding movement.

By way of example only, the present invention will now be described with reference to the following figures in which; Figure 1 is an inside view of a preferred female plug of the present invention; Figure 2 is a side view of the plug of Figure 1; Figure 3 is an end view of the plug of Figure 1; Figure 4 is an inside view of a preferred male plug of the present invention; Figure 5 is a plan view of the plug of Figure 4; Figure 6 is an end view of the plug of Figure 4; Figure 7 is a plan view of the plugs of Figure 1 and 4 when connected; Figure 8 is a side view of the connected plugs of Figure 7 and Figure 9 is an end view of the connected plugs of Figure 7.

Figures 1,2 and 3 illustrate respective inside, side and end views of a preferred female plug 11 of the present invention. The plug is shown with a cord 12 extending from a rear portion thereof. The outer sheath of the cord is clamped to the interior of the plug (this is not shown). In this way forces generated by pulling on the cord may at least partially be borne by the sheath of the cord. This should be compared to conventional plugs in which the cord is connected to the plug by means of the internal wires. Providing a clamp to the cord sheath can avoid or minimize damage to the wires if and when a cord is pulled with undue force (This can occur if the plug assembly becomes caught or snagged).

The plug 11 has a stepped contacting surface 13 which in use contacts a second plug. The contacting surface 13 has a forward 14 and a rear 15 portion. The forward portion 14 has a recess 16 extending along the length thereof and the rear portion 15 has a projection 17 extending along the length thereof. Intermediate the tow portions 14, 15 is a connecting face 18.

Three recesses 19, 20, 21 are located in the connecting face 18.

Figures 4,5, and 6 illustrate similar views of a preferred male plug of the present invention. The male plug is similar to the female plug and the same reference numerals have been used to indicate similar features. The male plug has three pins 22, 23, 24 extending from connecting face 18.

In use, the plugs are connected by engaging the corresponding grooves and projections in the respective forward and rear portions of the plugs and sliding the plugs relative to each other such that the pins and recesses engage. Figure 7 to 9 illustrate the connected plugs.

To disengage the plugs, the plugs are simply slid in the reverse direction.

It can be seen by reference to figure 8, that if either cord is pulled the force is borne by face 18. This prevents the plugs from being pulled apart.

Also, because the cords are securely clamped within the body, pulling is not likely to damage the wires or damage the electrical connections between the wires and the plug.

It will also be appreciated that due to the rounded shape of the connected plugs, there is less chance of snagging or catching when being pulled over objects such as roof battens. The plus are suitablle for connection with single or multi wired cords. Larger plugs may of course be used with larger cords or cables.

It will be appreciate that various changes and modificaitons may be made to the invention as described and claimed therein without departing from the spirit and scope of the invention.

Claims

1. An electrical plug, the plug having a body with an aperture located in a rear section thereof through which an electrical cord may pass, a connecting face having at least one pin extending therefrom or at least one recess extending therein, and a resistance zone which, when the plug is electrically connected to a second plug and the plug is pulled in the direction of a cord extending therefrom, the resistance zone contacts a section of the second plug and resists separation of the second plug and the plugs can be separated by sliding the plugs relative to each other in a direction towards the cord of the opposite plug.

2. The plug of claim 1, wherein the resistance zone is located on the contacting face.

3. The plug of claim 1, substantially as hereinbefore described with reference to Figures 1, 2 and 3 or Figures 4, 5 and 6. DATED this 2 9 th day of August 2000 PA JT CONSTRUCTIONS PTY LTD By their Patent Attorneys CULLEN CO.