GB2271890A

GB2271890A - Three-pole electrical plug

Info

Publication number: GB2271890A
Application number: GB9219707A
Authority: GB
Inventors: Tun-Li Su
Original assignee: GEM MACHINERY INDUSTRY Co
Current assignee: GEM MACHINERY INDUSTRY Co
Priority date: 1992-09-17
Filing date: 1992-09-17
Publication date: 1994-04-27
Also published as: GB9219707D0

Abstract

A three-pole plug has a sleeve (14) and pin support (5) injection moulded in one piece. The pin support has three slide grooves (512) each having a spring leaf (511) and recess (50) defining a shoulder (513). The pins (61) are each provided with a notch and two lugs in front of the notch. The notch and the lugs cooperate with the spring leaf and the shoulder respectively, so that the pin shall be fixed in place. The sleeve and the pin support with inserted pins are then injection molded for the second time to form a finished plug. <IMAGE>

Description

TITLE : A THREE-POLE PLUG BACKGROUND OF THE INVENTION It is known that three-pole plugs and associated sockets are safe in use and therefore, they are now widely used in the computer connection. One of such plugs A is shown in Fig. 6 which is characterized by that the pins A' which are otherwise exposed to outside are now hidden in a sleeve B which constitutes a junction portion. A specially formed front part of the socket C is adapted to insertion into the sleeve B so that the plug is electrically connected.

A conventional three-pole plug, as shown in Fig. 7, usually includes two parts, namely, the sleeve 1 and the pin base 2.

The sleeve 1 is generally injection molded and is made of one single type of material. After a pin base 2 with pins 21 is adapted to the molded sleeve 1, they are integrally injection molded again to form a plug. In manufacturing the plug, the three pins 21 are firstly manually inserted into a mould for the pin base before the pin base 2 illustrated in Fig. 7 is injection molded. The molded pin base 2 is then adapted to the sleeve 1 by clipping an upper and a lower cotters 22 into holes formed on tongues 12 of the sleeve 1 with the three pins 21 separately passing through corresponding pin holes 11 on the sleeve 1. The associated pin base 2 and sleeve 1 is then molded to form an integral plug through a third time injection.

Such a plug has, however, following disadvantages: 1. the pins 21 must be manually inserted into the mould for pin base 2 before the pin base 2 is injection molded. Since the mould for the pin base 2 is not designed with any means to adequately fix the pins 21, the manually inserted pins 21 tend to deviate from correct position. Such deviation of pins from their position may very possibly have reverse effect on quality of the plug because the injection molded plug with deviated pins may have poor contact with the socket when it is pluged into the latter.

2. There are at least three times of injection molding required to complete the manufacture of a plug, i.e., the injection molding of the sleeve 1, of the pin base 2, and of the integral plug. The time and cost for such injection moldings is high.

As a result, there was attempt made to improve the position deviation of manually inserted pins 21. A bridge 3 as illustrated in Fig. 8 is provided. The bridge 3 has three grooves 31 for the disposition of pins 21. Lugs 32 are provided at proper positions near the front of the grooves 31 such that the lugs 32 are frictionally engaged with recesses 23 formed on the pins 21 and thereby fix the pins 21 in place without unwanted shifting. The bridge 3 with positioned pins 21 and the sleeve 1 are then together injection molded to form an integral plug.

It is to be noted the above described bridge 3 is designed mainly to solve the problem of poor contact of the pins with the socket caused by the position deviation of the pins 21 in the conventional pin base 2. The sleeve 1 and the bridge 3 still have to be individually and separately injection molded at first and then to be integrally injection molded again.

The time and cost needed to make plug so structured is not improved anyway.

SUMMARY OF THE INVENTION The plug according to the present invention has a junction sleeve and pin base that are integrally injection molded at the very beginning. The pin base part is provided with slide guides for pins and passages for pins; the slide guides each have a spring leaf which may engage with a notch formed on each pin, and the pin passages each have a vertically cut end surface at where the pin having two side lugs may be stopped from moving any further. By this way, the pins may be clipped into the pin base part and fixed in place before the plug is finally injection molded. In the manufacture of the plug according to the present invention, better conduction effect than conventional three-pole plugs can be achieved and the times of injection molding required are reduced to two that economically enhances the productivity thereof.

BRIEF DESCRIPTION OF THE DRAWINGS The structure of the present invention and the technical means used to achieve the objects thereof can be best understood through referring to the following detailed description of preferred embodiments and the accompanying drawings wherein Fig. 1 is a three-dimensional perspective showing the internal structure of the plug according to the present invention; Fig. 2 is a side sectional view of the plug shown in Fig. 1; Fig. 3 is a vertical sectional view of the plug with three pins inserted into the pin base; Fig. 4 is a cross sectional view of the plug in which one pin inserted into the pin base can be seen; Fig. 5 is a three-dimensional perspective showing a finally injection molded plug according to the present invention; Fig. 6 illustrates the manner in which a three-pole plug connects to an associated socket;; Fig. 7 is an analytical perspective showing a conventional three-pole plug; and Fig. 8 is also an analytical perspective showing another type of conventional three-pole plug.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Please refer to Figs. 1, 2, the present invention mainly consists of a front junction sleeve portion 4 and a pin base portion 5. The junction sleeve portion 4 is mainly a housing 41 which is suitable for engaging with the front junction portion of a three-pole socket. There are three bottom holes 42 formed at bottom wall of the housing part 41 and disposed at positions suitable for three corresponding pins 61 to pass through. The plug of the present invention is characterized by that the front junction sleeve portion 4 and the pin base portion 5 are integrally molded at the very beginning. In the pin base portion 5, there are three slide grooves 51 for separately guiding the pins 61 to slide into corresponding pin passages 512 provided at front part of the pin base portion 5.Each of the slide grooves 51 is provided with a recess 50 at adequate position. Over each of the recesses 50, a spring leaf 511 inclinedly extending outward from the rear end of the recess 50 toward the other end of the recess 50 near the junction sleeve portion 4. The pin passages 512 are separately disposed in front each of the spring leaves 511 and are communicable with the junction sleeve portion 4 via the bottom holes 42 and each has a vertically cut end surface 513 facing the spring leaf 511. The pins according to the present invention each has a notch 612 formed at rear end and two lugs 611 provided at two sides between the notch 612 and the rear end of the pin 61. The positions of the lugs 611 and the notch 612 shall permit the pin 61, when being inserted into the pin base portion 5 via the slide groove 51 and being pushed toward in the direction of the junction sleeve portion 4 as shown in Fig. 3, to be firmly stuck in the slide groove 51 with the spring leaf 511 engaging with the notch 612 and the lugs 611 bearing against the vertically cut end surface 513 of the pin passage 512. Since the elasticity of the spring leaf 511 facilitates the sliding of pin 61 toward the junction sleeve portion 4 and the pin 61 shall be fixed in place and can not be withdrawn when the spring leaf 511 extending into the notch 612 formed on the pin 61.On the other hand, the two lugs 611 bearing against the end surface 513 of the pin passage 512 shall prevent the pin 61 from moving further into the pin passage 512, and accordingly, the housing 41 of the front junction sleeve portion 4. By this way, the pin 61 can be well located, as shown in Fig. 4, without any unwanted shifting or deviation from desired position. At this point, a second time injection molding can be performed to integrally wrap the sleeve portion 4, pin base portion 5, and the pins 61 together to form a complete three-pole plug as shown in Fig. 5 which shall provide better conduction effect than the conventional three-pole plug does.

The major advantages of the plug according to the present invention are: 1. The sleeve and the pin base are two portions of an integrally injection molded piece, and no sleeve, bridge, or pin base requires individual and separate injection molding. That is, the times of injection molding can be reduced by one and the time and cost for such process is largely saved.

2. The spring leaf of the slide grooves and the vertically cut end surface of the pin passages on the pin base portion may together with the notch and lugs formed on the pins firmly fix the pins in place to get excellent conduction effect.

Claims

What is claimed is:

A three-pole plug comprising a front junction sleeve portion and a rear pin base portion which are integrally injection molded into one piece without the need to individually and separately injection molding any of said sleeve portion or said pin base portion; said front junction sleeve portion mainly consisting of a housing which is suitable for adapting to a junction part of a three-pole socket and has three bottom holes formed on its bottom surface generally disposed to correspond to the three pins of said plug; said pin base portion being provided with three slide grooves each of which is provided with a recess over which a spring leaf is inclinedly extended outward from rear end of said recess toward another end thereof near said sleeve portion, and a pin passage which is located in front of said recess and said spring leaf, communicable with said bottom holes formed on bottom surface of said sleeve portion and thereby allowing a pin to pass through there and extend into said sleeve portion, and has a vertically cut end surface facing said spring leaf; said pins each having a notch formed near its rear end thereof and two lugs provided at two sides thereof near positions in front of said notch such that when each of said pins is inserted into one of said slide grooves and is pushed toward said pin passage, said spring leaf in said slide groove engages with said notch on said pin and said two lugs bear against said vertically cut end surface of said pin passage to fix said pin in place with its front end passing through said pin passage and said bottom holes on bottom surface of said sleeve portion and extending into said housing of said sleeve portion without unwanted deviation from position or shifting and thereby provides better conduction effect.