WO2009059335A1

WO2009059335A1 - Detonator connector

Info

Publication number: WO2009059335A1
Application number: PCT/ZA2008/000096
Authority: WO
Inventors: Johannes Petrus Kruger
Original assignee: Detnet South Africa (Pty) Limited
Priority date: 2007-10-31
Filing date: 2008-10-22
Publication date: 2009-05-07
Also published as: PE20091148A1; CL2008003252A1; AR068931A1; ZA200905314B

Abstract

A detonator connector which includes a housing which is formed from at least first and second components which are interengageable to form an enclosure, at least one electrical terminal inside the enclosure to which at least a first electrical conductor can be connected, and at least a first, non-electrically conductive insert formed from a resiliently compressible material, within the enclosure which contacts, and which forms a watertight seal around the terminal and at least part of the first electrical conductor.

Description

DETONATOR CONNECTOR

BACKGROUND OF THE INVENTION

[0001] This invention relates to a connector which is suitable for use with a detonator of the kind used for explosive blasting.

[0002] In a blasting system a plurality of electrical or electronic detonators are interconnected in a desired configuration using electrical conductors. The number of connections which are made can be substantial. A need therefore exists for a connector which is of relatively low cost and which can be used, with ease, to interconnect conductors rapidly and efficiently.

[0003] Another factor which has an influence on the design of a connector is that in some applications a connector, once connected to electrical conductors, must be left in situ for an extended period before blasting takes place. The connector may, during this period, be exposed to the weather, harsh underground conditions or to explosive material which, in turn, may be an emulsion or gel-type explosive. It is important, in order to ensure the integrity of the electrical connections which are effected through the use of the connector, to prevent the ingress of moisture, other mining-related liquids, and other foreign material into the connector. To achieve this objective use is generally made of a grease-like paste which is water and oil-resistant and which fills an interior of the connector. This type of paste however is messy, and creates manufacturing and application difficulties. [0004] It is an object of the present invention to provide a detonator connector which, at least partly, addresses the aforementioned problems.

SUMMARY OF THE INVENTION

[0005] The invention provides a detonator connector which includes a housing which is formed from at least first and second components which are interengageable to form an enclosure, at least one electrical terminal inside the enclosure to which at least a first electrical conductor can be connected, and at least a first, non-electrically conductive insert formed from a resiliently compressible material, within the enclosure which contacts, and which forms a watertight seal around, the terminal and at least part of the first electrical conductor.

[0006] The first and second components may be interconnected in any appropriate way which permits movement of one component relative to the other component. Preferably, in this respect, use is made of a hinge joint between the two components.

[0007] The connector may include securing formations which act to retain the components in an interengaged configuration. Preferably the securing formations are in the nature of clips which keep the components interengaged. These clips may be actuable to release the components so that one component can then be moved relative to the other component.

[0008] The resiliently compressible material may be a foamed material which is water- resistant and oil-resistant and of a closed cell structure. A preferred material though is a wax or gel which, when heated to a critical temperature, is a liquid. This allows the wax or gel to be poured into a mould or into one or both components, whereafter the wax or gel can set into a water-resistant and electrically insulating body.

[0009] "Gel", as used herein, includes a semisolid, jelly-like material. An advantage of a gel is that, to some extent, it exhibits thixotropic properties which allow the gel to flow, at least to a limited degree, when under pressure. The characteristic helps to shape the gel around the electrical terminal. Also, the gel can be placed into the enclosure of the connector under factory conditions. The gel does not easily adhere in a permanent manner to other materials and thus does not soil or dirty the hands of a technician who uses the connector. Portions of a gel body which contact each other do, however, then adhere to one another - a feature which helps the gel to form a protective, liquid- and foreign material-proof shield around the electrical terminal and the electrical conductor or conductors which are connected to the terminal.

[0010] The electrical terminal may be of any appropriate kind and preferably is an electrical insulation displacement terminal. The nature and number of terminals which are employed are determined, at least, by the intended use of the connector and the number of conductors which are to be interconnected.

[0011] At least one of the components may be formed with a first conductor guide which facilitates engagement of the housing with a first conductor from a first direction. The connector may include at least a second conductor guide which facilitates engagement of a second conductor with the housing from a second direction which may be transverse to the first direction. [0012] The housing may include conductor restraining structure which provides a degree of mechanical fixing of each conductor to the housing. This structure may be frictionally engageable with sides of a conductor which, preferably, is insulated at the point of engagement.

[0013] Conductors with which the connector is used may be embodied in any appropriate wire geometry e.g. single, duplex or multiplex, multistranded, round, ribbon etc. These are non-limiting examples.

[0014] The first insert may fit closely within the confines of the first component. The connector may include a second, non-electrically conductive insert which is similar to the first, non-electrically conductive insert and which is engaged in a similar manner with the second component.

[0015] Preferably each electrical terminal is surrounded by structure, of the respective component, which forms a compartment around the terminal and the compartment is filled with the resiliently compressible material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention is further described by way of examples with reference to the accompanying drawings in which :

Figure 1 is a plan view of a detonator connector according to a first form of the invention in an open configuration, Figure 2 is a perspective view of the connector of Figure 1 with electrical conductors connected to the connector, Figure 3 is a side view of the connector shown in Figure 1 ,

Figure 4 is a side view of the detonator connector, to which electrical conductors are connected, in a closed configuration, but inverted, Figure 5 is similar to Figure 4 but shows the connector in cross-section, Figure 6 shows the connector of Figure 4, in perspective,

Figure 7 shows the connector in an open configuration, in plan, and

Figure 8 schematically illustrates the use of a number of connectors each of the kind shown in Figure 1 , in a blasting system.

DESCRIPTION OF PREFERRED EMBODIMENT

[0017] Figures 1 to 6 of the accompanying drawings illustrate an electrical connector 10 according to the invention which includes a housing 12 which is moulded from a suitable material e.g. a plastics material.

[0018] The housing includes a first component 14 and a second component 16. The components have formations 18 and 20 respectively which are pivotally interconnected by means of a pin or shaft 22 so that one component is movable relatively to the other component.

[0019] The first component has a first substantially dished rectangular section 30 from which projects a first handle portion 32. Spaced walls 34A, 34B and 34C, and 34D and 34E, respectively extend upwardly from a base of the rectangular section and define respective compartments 36A and 36B. Two sets of relatively small and closely spaced walls 38A and 38B, and 40A and 4OB, respectively are in the compartments 36A and 36B respectively. [0020] The handle portion 32 is flanked by flexible, movable clip formations 46 and 48 respectively. A guide channel 50 extends longitudinally through the handle portion towards the rectangular section 30. The guide channel has at least one inwardly extending, retention formation 52.

[0021] The second component 16 has a dished rectangular section 60. Two electrical insulation displacement terminals 62 and 64 respectively extend upwardly from a base 66 of the section 60. The number of terminals used can be varied according to requirement. The construction of these terminals is not described in detail for this type of terminal is known in the art. In general terms though it can be said that each terminal includes a shaped slotted section into which an insulated electrical conductor can be pushed with a tight fit. This tight interengagement causes the terminal to displace insulation from the conductor and the inner core, which is metallic and conductive, is then electrically connected to the terminal. In this example the terminal 62 has two of these sections designated 68A and 68B, which are in line, and a third section 68C which is displaced at a right angle to the sections 68A and 68B. The terminal 64 is similarly constructed - see Figure 7. Each terminal is mounted with, and at least partly enclosed by, a corresponding relatively small compartment 70 and 72 respectively.

[0022] A handle portion 80 extends from the rectangular section 60. A guide channel 82 extends longitudinally along the portion between two small ribs 84 and 86 respectively, towards the rectangular section 60. Small opposing slots 88A and frictional retaining formations 88B are formed in upper edges of the ribs. [0023] A rectangular wall 90 surrounds the terminals 62 and 64. Opposing wall segments 9OA and 9OB are formed with fairly deep conductor-locating slots 92A and 94A, and 92B and 94B respectively, which oppose each other.

[0024] An insert 90 formed from a non-electrically conductive resiliency compressible material fits snugly inside the rectangular section 30 surrounded by the walls 34A, 34C and 34D, 34E. The insert material fills each compartment, including the spaces between the walls 38A and 38B, and 4OA and 4OB.

[0025] Two electrical leads 96 and 98 respectively are engaged with the connector 10. The lead 96 includes an outer sheath 100 and two insulated electrical conductors 102 and 104 are enclosed within the sheath. The lead 98 comprises a pair of insulated electrical conductors 106 and 108 respectively which are shown spaced apart but which, away from the connector, form a twisted pair. This wire geometry is exemplary only, and non-limiting.

[0026] A portion of the sheath 100 is stripped from the lead to expose the conductors 102 and 104. The conductor 102 is engaged with the displacement sections 68A and 68B of the terminal 62 and the conductor 104 is similarly engaged with the displacement sections 68A and 68B of the terminal 64.

[0027] The conductor 106 is engaged with the displacement section 68C of the terminal

62 and the conductor 108 is similarly engaged with the corresponding displacement section 68C of the terminal 64. This conductor 106 is located in the aligned slots 92A and 92B, and the conductor 108 is located in the aligned slots 94A and 94B. In this way the conductors 102 and 106 are electrically interconnected, and the conductors 104 and 108 are electrically interconnected.

[0028] A length of the lead 96, adjacent the exposed conductors 102 and 104, is pushed into the guide channel 82, and is forced past the formations 88B.

[0029] The sheath is lightly deformed to allow this movement but expands again, once the lead is fully in the channel. The first component 14 is then moved so that it overlies the second component 16. The clip formations 46 and 48 have respective hooks 110 which are respectively engaged with undercut ledges 112 on sides of the portion 80. This keeps the two components securely fixed to each other. The formation 52 bears on the lead 96 inside the guide channel 82 and helps to keep the lead firmly mechanically locked to the connector. The conductors 106 and 108 extend transversely to the lead 96.

[0030] A wall 114 at a perimeter of the component 14, which opposes a perimeter wall 116 of the component 16, pushes the conductors 106 and 108 downwardly in the slots 92A, 92B, 94A and 94B and this action assists in mechanically locking the conductors to the component.

[0031] As the components are interengaged the insert 90 is placed under pressure at a number of locations. The insert is trapped inside the compartments 36A and 36B and particularly within the spaces between the walls 38A and 38B, and 4OA and 4OB, respectively. These spaces directly oppose corresponding upstanding portions of the terminals 92 and 94 to which the leads 106 and 108 are connected. Parts of these walls and parts of the walls 34A to 34E also surround lower portions of the terminals, and directly oppose upper surfaces of the walls of the compartments 70 and 72. The insert is resiliency distorted to some extent and is deformed in a manner which closely follows the outlines of the non-compressible portions of the components against which the insert abuts. The insert is thus formed into close engagement with outer surfaces of the electrical conductors and the corresponding terminals, and in each case is enclosed in the respective compartment around the terminal, and so forms a two-stage oil and water-resistant shield around each electrical connection.

[0032] It has been found through experimentation and testing that the inserts provide watertight seals which are effective for extended periods.

[0033] The insert 90 can be made from different materials. Suitable materials are: an appropriate wax which is poured in liquid form into the section 30 and then allowed to set; a closed cell foam material which is preformed and then placed into the section 30, and a gel.

[0034] The last mentioned material is particularly suitable for it exhibits the desirable properties which have been referred to in that it is water- and oil- resistant, it can distort and deform under pressure in a manner which then allows contacting portions of the gel to bond to each other, and it does not stick to a user nor does it smear onto surfaces. A gel insert tends to remain in an integral, non-messy body which can be shaped by forces exerted on the body to fill a surrounding enclosure substantially completely, while retaining desirable water- and oil- resistant properties.

[0035] The clips 46 and 48 which are resiliency mounted to the handle portion 32, can be urged slightly towards each other so that the hooks 110 are disengaged from the undercut ledges 114. This allows the connector to be opened, if necessary. The gel insert may then expand or distort slightly, as forces on the insert are changed, but when the connector is closed again the gel insert is compressed, as before, and once more takes up its previous shape and size.

[0036] Figure 7 illustrates how a plurality of the connectors designated 1OA, 1OB, 1OC etc are used in a blasting system 120. The system includes a number of detonators 122A, 122B etc which are placed in explosives 124 in respective boreholes 126A, 126B etc. Each detonator is connected to a respective lead 96A, 96B etc which corresponds to the lead 96 shown in Figure 2. A twisted wire pair of trunk lines 128 which corresponds to the lead 98 shown in Figure 2, extends between successive connectors. Electrical connections required in the blasting system are made with ease using the connectors of the invention.

[0037] In the preceding description the connector 10 is capable of being used to make electrical connections between a first pair of conductors and a second pair of conductors. The invention is not confined to this particular configuration, however, for the principles of the invention can be used with single conductor leads. Similarly, if required, the principles of the invention can be used with conductors with leads which have more than two conductors.

[0038] The gel body, as described, can be replaced by, or used in conjunction with, any other suitable material. For example use could be made of a resiliently compressible foam material with a closed cell structure, which is shaped to fit inside the connector housing and which is compressed into intimate sealing contact with the conductors upon closure of the housing components. A similar effect can be achieved through the use of an appropriate wax. These materials can be used alone, or in any desired combination. Depending on requirements it may be desirable to shape the insert, irrespective of the material from which it is made, with openings or other formations which take account of the size, position and number of the insulation displacement terminals incorporated in the connector. This however is by no means essential for it falls within the scope of the invention to provide a connector wherein an insert or inserts, of the kind described, cover an interior of the connector housing including the insulation displacement terminals. For example in one approach the insert, typically a gel or wax, is simply pushed over the terminals, on one housing component, to allow the terminals to protrude through the insert and the conductors are then connected to the terminals. An optional second insert on the other housing component could then be brought to bear on the conductors when the housing is closed. In a different approach the conductors are first connected to the terminals on one component housing. At least one insert, of any of the kinds mentioned, carried by the other connector housing is then brought into close sealing contact with the terminals and conductors when the housing is closed.

Claims

1. A detonator connector which includes a housing which is formed from at least first and second components which are interengageable to form an enclosure, at least one electrical terminal inside the enclosure to which at least a first electrical conductor can be connected, and at least a first, non-electrically conductive insert formed from a resiliently compressible material, within the enclosure which contacts, and which forms a watertight seal around, the terminal and at least part of the first electrical conductor.

2. A detonator connector according to claim 1 wherein the first and second components are interconnected in a way which permits movement of one component relative to the other component.

3. A detonator connector according to claim 1 or 2 which includes securing formations which act to retain the components in an interengaged configuration.

4. A detonator connector according to any one of claims 1 to 3 wherein the electrical terminal is an electrical insulation displacement terminal.

5. A detonator connector according to any one of claims 1 to 4 which includes a first conductor guide which facilitates engagement of the housing with a first conductor from a first direction and a second conductor guide which facilitates engagement of a second conductor with the housing from a second direction.

6. A detonator connector according to any one of claims 1 to 5 wherein the resiliently compressible material is selected from a gel, wax, and a foam material which has a closed cell structure.

7. A detonator connector according to any one of claims 1 to 6 wherein the housing includes structure which, within the enclosure, forms at least one compartment which surrounds a corresponding terminal and is filled with the resiliently compressible material.