WO2007113313A1

WO2007113313A1 - Coupling system

Info

Publication number: WO2007113313A1
Application number: PCT/EP2007/053296
Authority: WO
Inventors: Matthew White
Original assignee: Kingfisher Plc
Priority date: 2006-04-06
Filing date: 2007-04-04
Publication date: 2007-10-11
Also published as: GB0606941D0; GB2436900A

Abstract

A latching mechanism for a plug and socket cable connector includes an arm (28) having a free end and extending parallel to the cable axis, a locking lug projecting radially outwards from the arm near its end, and an inclined surface (38) being formed on an outer part of the arm; a collar surface located substantially coaxially with the cable and latching mechanism; and a cam ring with a cam surface (44) formed on an inner surface located substantially coaxially with the cable and latching mechanism, the cam ring embracing the arm, wherein the free end of the arm is based outwardly such that when in its normal position when the latching mechanism is inserted into a sleeve opening (14), the arm holds the lug in a position that engages in a sleeve aperture (IS), and when the collar is moved axially relative to the arm, the cam surface is caused to act on the inclined surface and urge the arm against the bias so as to move the lug away from its normal position and out of the aperture.

Description

COUPLING SYSTEM Technical field [0001] This invention relates to coupling systems such as may be used for connecting a power cable to an electrical device such as a power tool or the like. Background art [0002] Electrical power tools such as drills, saws, and other domestic electrical devices such as hair driers and vacuum cleaners are provided with cables that are connected directly to the electrical system at the tool end and have a plug for connection to a domestic electrical supply at the other end.

The disadvantage with this approach is that the cable is often not long enough to reach from the closest supply point to the place where the tool is to be used. Alternatively, if the cable is very long, it can become tangled easily and cause inconvenience or danger for the user. [0003] There have been certain previous proposals for providing a removable power cable to such tools or devices. Simple push-fit connections are well-known but have the disadvantage that they can be easily disconnected in use. Therefore, different types of locking system have also been proposed. [0004] One form of lock is a twist-fit or threaded connector. Examples of these can be found in EP0124389, GB1445880, and GB2356496. [0005] Another form of lock uses resilient or spring-loaded latches to engage locking elements on one part in corresponding formations on another.

Examples of these can be found in DE3123825, DE3150424, and

EP0617482. [0006] While these previous systems do lock the cable into the tool and prevent accidental disconnection, they all have some problem in ease of use; either the need to use two hands for connection or disconnection, or difficult manipulation of the locking elements. [0007] It is an object of this invention to provide a cable connection system with a lock to prevent accidental disconnection that is easier to use than these previous systems. Disclosure of the invention

[0008] This invention provides a coupling device for a plug and socket cable connector including a sleeve with an opening and at least one aperture for receiving a locking lug, the coupling device comprising: a latching mechanism including an arm having a free end and extending parallel to the cable axis, a locking lug projecting radially outwards from the arm near its end, and an inclined surface being formed on an outer part of the arm; a collar surface located substantially coaxially with the cable and latching mechanism; and a cam ring with a cam surface formed on an inner surface located substantially coaxially with the cable and latching mechanism, the cam ring embracing the arm, wherein the free end of the arm is biased outwardly such that when in its normal position when the latching mechanism is inserted into the sleeve opening, the arm holds the lug in a position that engages in the sleeve aperture, and when the collar is moved axially relative to the arm, the cam surface is caused to act on the inclined surface and urge the arm against the bias so as to move the lug away from its normal position and out of the aperture.

[0009] In one embodiment, the collar and cam ring are formed as a single body. The inclined surface can be formed at the outer extremity of the arm which is particularly preferred in this case.

[0010] In another embodiment, the arm is attached to the collar and the cam ring is fixed. In this case it is preferred that the collar and arm are formed as a single body.

[0011] Preferably, the latching mechanism has a more than one arm, each having a lug and an inclined surface. A particularly preferred form has a pair of arms on opposite sides of the latching mechanism. In this case, a preferred form of biasing is a compression spring mounted between the extremities of the arms. Other forms of biasing could also be used, such as the use of resilient materials to form the arms. The inclined surface of the arm is typically inclined radially outwardly towards its outer extremity and the cam surface of the collar is correspondingly angled. [0012] The invention also provides a coupling system for a cable connector comprising a coupling device as defined above and a sleeve with an opening and an aperture for receiving the locking lug. [0013] The coupling device is preferably connected to a cable and the sleeve is preferably connected to an electrical device to which the cable is to be connected. [0014] The coupling device and sleeve typically each contain electrical contacts which are brought together when the latching mechanism is inserted into the sleeve. [0015] It is also preferred that the collar abuts against the sleeve when the latching mechanism is inserted and the lug is engaged in the aperture. [0016] These features and other aspects of the invention will be apparent from the description below. Brief description of the drawings [0017] Figure 1 shows a perspective view of a first embodiment of coupling system according to an embodiment of the invention;

Figure 2 shows a perspective view of the coupling device of Figure 1

Figure 3 shows a cross-section through the coupling system of Figure 1 ;

Figure 4 shows the end fitting of the coupling device of Figures 1-3 with the top removed for clarity; and

Figure 5 shows a perspective view of a coupling device according to a second embodiment of the invention;

Figure 6 shows a cross section through the device of Figure 5; and

Figure 7 shows the same view as Figure 6 with parts omitted for clarity. Mode(s) for carrying out the invention [0018] The coupling system shown in Figures 1-4 is suitable for electrical devices such as power tools (electric drills, saws, etc.), garden tools (electric mowers, edging tools, trimmers, etc.) and any other tool or device requiring connection to an electrical supply. There are essentially two parts to the system: a sleeve 10 and a coupling device 12. The sleeve 10 is in the form of a cup-shaped moulding having an opening 14 at one end and opposing locking apertures 16 formed in the sidewall of the sleeve 10 near the opening 14. A pair of contact openings 18 is provided in the base of the sleeve 10. In use, the sleeve 10 is mounted in a tool, the opening 14 of the sleeve 10 typically being flush with the surface of the tool casing (not shown). The contact openings 18 are positioned such that electrical power contacts on the tool project into the sleeve so that corresponding contacts on a power lead (not shown) can make electrical contact via the connecting device 12 described in more detail below.

[0019] The coupling device 12 comprises a cable end fitting 20 formed from a moulded plastic structure that fits around the end of an electrical power cable (not shown). A flexible, tubular stress reliever 22 is located at the end of the fitting 20 where the cable enters. The two conductors of the cable are separated in the end fitting 20 and lead though channels 24 to openings 26 where grip contacts are located (not shown). The shape and spacing of the openings correspond to the contact openings 18 in the sleeve 10 so that blade contacts projecting through the contact openings 18 can enter the openings 26 and engage the grip contacts.

[0020] The end fitting 20 also includes a latching mechanism comprising a pair of latch arms 28 located in a central cavity 30 as is shown in Figure 4. The arms 28 are formed from a resilient plastic material and are fixed near the outer end of the end fitting and extend back along the cavity parallel to the end fitting axis. At the end of each arm 28 is an outward facing locking lug 32 which projects through a slot 34 in the side of the end fitting 20 such that the tip of the lug 32 projects from the surface of the fitting 20. The end of the lug 32 has a sloped surface 36 facing the outer end of the fitting. The end of each arm 30 has an outer inclined surface 38 formed thereon which also projects through the slot 34. A coil compression spring 40 is located between the arms 28 to bias them apart.

[0021] A collar 42 having an integrated cam ring is located around the outside of the end fitting 20 in the region such that the inclined surfaces 38 are embraced by the collar 42 while the lugs 32 are exposed. The inner surface of the collar 42 is formed with a cam surface 44 of corresponding slope to the inclined surface 38. By pulling on the collar 42 away from the outer end of the fitting 20, the cam surface 44 acts on the inclined surfaces 38 so as to force the ends of the arms 28 to flex inwards against the effect of the spring 40 so that the lugs 32 retract in the slot below the surface of the fitting. Releasing the collar allows the spring 40 to force the arms 28 apart such that the lugs 32 project from the slot 34 and the collar is advanced by the action of the inclined surfaces 38 on the cam surface 44.

[0022] In use, the coupling device 12 is engaged in the sleeve 12 merely by pushing the outer end of the fitting 20 into the sleeve opening 14. When the lugs 32 reach the edge of the sleeve 12, the sloped surface cause the arms 28 to be pushed in against the effect of the spring 40 until the lugs 32 will fit inside the sleeve 10. As the coupling device12 is pushed further into the sleeve 10, the lugs 32 reach the locking apertures 16 and are forced out under the effect of the spring 40 (alignment of the apertures 16 and lugs 32 can be ensured by making the end fitting 20 and sleeve opening 14 of a suitable corresponding shape). The spacing between the locking apertures 16 and the outer edge of the sleeve 10, and between the lugs 32 and inclined surfaces 38 are such that when the lugs 32 are engaged in the locking apertures 16, the outer edge of the collar 42 contacts the outer edge of the sleeve (this is the position shown in Figures 1 and 3.

[0023] When the coupling device 12 is locked into the sleeve 10 by the lugs 32, it is impossible to accidentally remove the coupling device merely by pulling on the cable. In order to remove the device 12, it is necessary to pull back on the collar 42 until the lugs 32 are withdrawn from the locking apertures 16. Thus, the pulling action necessary to unlock the device 12 is the same as that to remove the device 12 from the sleeve 10 making deliberate disconnection a relatively easy action. It may also be desirable to configure the device and sleeve such that unlocking for safety reasons or to safeguard against damage can be achieved merely by pulling with a very strong force. In the embodiment shown, this would be achieved by breaking the lugs.

[0024] In the embodiment described above, the arms are attached to the end fitting and the collar and cam ring are formed as an integral unit, movement of the collar moving the cam ring over the inclined surfaces of the arms to move the lugs out of the apertures. In the embodiment described below in relation to Figures 5-7, a different construction is used in which the arms are formed on the collar and the cam ring is fixed to the end fitting.

[0025] In the embodiment of Figures 5-7, the end fitting 50 has similar connection to the cable as described above. However, in this case, a pair of channels 52 are provided on opposite sides of the fitting 50. A cam ring 54 is integrally formed around the end fitting 50 with slots 56 formed over the channels 52 and cam surfaces 58 formed on the inner surface of the cam ring 54 in the slots 56 (see Figure 7).

[0026] The collar 60 has a shaped grip surface 62 and a pair of axially extending arms 64 formed integrally from a resilient plastics material. The arms 64 have lugs with sloped surfaces 66 and inclined surfaces 68 (similar to those of the embodiment described above. However, in this case the inclined surface 68 is between the lug 66 (positioned essentially at the free end of the arm 64) and the fixed part of the arm where it attaches to the collar 60. When the collar 60 is positioned on the end fitting 50, the arms 64 lie in the channels 52, projecting through the slots 56 in the cam ring 54. The sloped surfaces of the lugs 66 and the inclined surfaces 68 project above the surfaces of the grooves 52, the inclined surfaces 68 bearing on the cam surfaces 58 of the cam ring 54.

[0027] The sleeve is the same as described above in relation to the embodiment of Figures 1-4 and is omitted here for clarity.

[0028] In use, the collar 60 is pulled back using the grip surface 62. The cam surfaces 58 and inclined surfaces 68 inter engage, causing the arms 64 to be forced inwards away from their natural position to withdraw the lugs to withdraw from the locking apertures 16 and allowing the device to be disconnected from the sleeve. Insertion of the device into the sleeve is performed in the same way as for the previous embodiment: by push fitting, with the sloped surfaces depressing the arms until the lugs 66 can spring out into the locking apertures 16. It will be appreciated that various changes can be made while staying within the scope of the invention. For example, the number and arrangement of arms can be varied, as can the materials of construction and the spring structure used for biasing.

Claims

1. A coupling device for a plug and socket cable connector including a sleeve with an opening and at least one aperture for receiving a locking lug, the coupling device comprising: a latching mechanism including an arm having a free end and extending parallel to the cable axis, the locking lug projecting radially outwards from the arm near its end, and an inclined surface being formed on an outer part of the arm; a collar surface located substantially coaxially with the cable and latching mechanism; and a cam ring with a cam surface formed on an inner surface located substantially coaxially with the cable and latching mechanism, the cam ring embracing the arm, wherein the free end of the arm is biased outwardly such that when in its normal position when the latching mechanism is inserted into the sleeve opening, the arm holds the lug in a position that engages in the sleeve aperture, and when the collar is moved axially relative to the arm, the cam surface is caused to act on the inclined surface and urge the arm against the bias so as to move the lug away from its normal position and out of the aperture.

2. A coupling device as claimed in claim 1 , wherein the collar and cam ring are formed as a single body.

3. A coupling device as claimed in claim 1 or 2, wherein the inclined surface is formed at the outer extremity of the arm.

4. A coupling device as claimed in claim 1 , wherein the arm is attached to the collar and the cam ring is fixed.

5. A coupling device as claimed in claim 4, wherein the collar and arm are formed as a single body.

6. A coupling device as claimed in any preceding claim, wherein the latching mechanism has a pair of arms on opposite sides of the latching mechanism.

7. A coupling device as claimed in claim 6, wherein a compression spring is mounted between the extremities of the arms to cause the biasing.

8. A coupling device as claimed in any preceding claim, wherein in the inclined surface of each arm is inclined radially outwardly towards its outer extremity and the cam surface of the collar is correspondingly angled.

9. A coupling system for a cable connector comprising a coupling device as claimed in any preceding claim and a sleeve with an opening and one or more apertures for receiving respective locking lugs.

10. A coupling system as claimed in claim 9, wherein the coupling device is connected to a cable and the sleeve is connected to an electrical device to which the cable is to be connected.

11. A coupling system as claimed in claim 9 or 10, wherein the coupling device and sleeve each contain electrical contacts which are brought together when the latching mechanism is inserted into the sleeve.

12. A coupling system as claimed in claim 9, 10 or 11 , wherein the collar abuts against the sleeve when the latching mechanism is inserted and each lug is engaged in its repsective aperture.