Electrical connector with locking ring

Abstract: An electrical connector, particularly for use with solar panels, has connector members which have male and female fitting parts containing electrical terminals. The fitting parts have respective locking elements which interengage to restrain disconnection. The female fitting part has a front portion which is elastically expanded on engagement with the relatively rigid male fitting part, and a second portion rearwardly of the portion which is less elastic than the front portion.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an electrical connector, particularly but not exclusively for an electric connection of wiring, such as a cable or the like, of a solar panel module. Description of the Prior Art A solar panel for use in a solar-energy power generation system is constructed of a plurality of modules connected one with another in series. A specific connector is used for an electric connection of the modules. A known connector of this kind and its defects will now be described. As shown in Fig. 7, a single pole connector of this kind is constructed of a plug-side connector member C1 having a cylindrical housing 1 accommodating a plug terminal 2 which is a male terminal, and a socket-side connector member C2 having a cylindrical housing 3 accommodating a socket terminal 4 which is a female terminal. A female fitting part 5 is provided at the front side of the housing 1 of the connector member C1, and a hollow sleeve-shaped male fitting part 6 is provided at the front side of the housing 3 of the connector member C2. As shown in Fig. 8, the plug terminal 2 and the socket terminal 4 are electrically connected with each other by fitting the male fitting part 6 in the female fitting part 5. Reference symbols W1 and W2 denote electric wires connected to the terminals and extending from the connector members C1 and C2, respectively. The peripheral surface 6a of the male fitting part 6 is tapered towards its front end to facilitate insertion into the female fitting part 5. In this known connector, the entire housing 1 of the plug-side connector member C1 including the female fitting part 5 and the entire housing 3 of the socket-side connector member C2 including the male fitting part 6 are formed of the same plastics material such as PVC which is comparatively hard and has a low degree of elasticity. Thus, the fitting parts 5 and 6 have mechanical properties such that they are hard and are difficult to elastically deform. Thus, it is difficult to obtain a mechanical effect that the fitting resistance of the fitting parts 5 and 6 is low when they are being fitted together, while their removal or disconnection resistance is high after they are fitted together. That is to say, when a construction in which the male fitting part 6 is tight in the female fitting part 5 is adopted, in consideration of the force for connecting them with each other, it is hard to disconnect the male fitting part 6 from the female fitting part 5 and hard to fit the former in the latter. That is, the operability in connecting the connector members C1 and C2 is poor. When a construction in which the male fitting part 6 fits loosely in the female fitting part 5 is adopted in consideration of operability, it is easy to fit the parts together but also easy to disconnect them. That is, the plug terminal 2 and the socket terminal 4 are not connected with each other stably. In this known connector, to prevent the fitting parts 5 and 6 from being disconnected, a locking rib 7 is formed on the peripheral surface of the male fitting part 6 and a locking groove 8 is formed on the inner peripheral surface of the female fitting part 5. The rib 7 and the groove 8 are engaged when the male fitting part 6 is fitted in the female fitting part 5. The connector alternatively has a plurality of the locking ribs 7 and a plurality of the locking grooves 8 formed axially continuously in the shape of wave in section on the fitting parts 5 and 6. The rib 7 and groove 8 allow the male fitting part 6 to be loosely fitted in the female fitting part 5, but because the parts 5 and 6 are hard to elastically deform, the locking rib 7 gives rise to a large fitting resistance. Thus, the fitting operation in this construction is not substantially different from the operation of press fitting the male fitting part 6 in the female fitting part 5 in the construction having neither locking rib 7 nor locking groove 8. US-A-4284312 shows a three-pole connector having mating housings containing the terminals. The male housing is of rigid plastics material, while the female housing is of PVC elastomeric material so as to elastically engage the male housing. In the engagement region the male housing has a smooth exterior. The female housing has an array of annular ribs which seal to the male housing and establish engagement and disengagement forces. EP 0 726 616, wich is considered as the closest prior art, shows a co-axial cable connector in which the body of the female terminal deforms on connection to allow engagement of an annular projection on the male terminal with an annular recess. SUMMARY OF THE INVENTION The present invention seeks to avoid or reduce the above-described problems. Therefore, it is an object of the present invention to provide an electrical connector in which a male fitting part can be fitted easily in a female fitting part while they are prevented from being easily disconnected from each other. This allows a connection operation to be performed with high efficiency, and allows the terminals to be connected stably with each other. According to the invention there is provided an electrical connector according to claim 1. In the construction of the invention, when the male fitting part fits in the female fitting part, the front portion of the female fitting part expands elastically, thus relieving the fitting resistance of the locking elements and allowing easy receipt of the male fitting part. Accordingly, the construction allows the fitting resistance to be small. After the male fitting part is fully received, the female fitting part returns, e.g. to its original shape, due to its elasticity. Thus, the fitting state can be reliably maintained by the locking operation of the locking elements. The disconnection force required can be greater than the connection force, due to the shape of the locking elements. Owing to the action of the construction, it is possible to satisfy the apparently opposite demands that it is easy to fit the male fitting part in the female fitting part and difficult to disconnect them from each other. Preferably the first locking element is a locking projection on the exterior surface of the male fitting part and the second locking element is a locking recess in the interior surface of the female fitting part, and the female fitting part has at its front end a contact surface located so as to be engaged by the locking projection when the male fitting part is inserted into the female fitting part so as to provide resistance to the insertion. In this case, in the fitting operation: (1) The locking projection portion collides with the front end of the female fitting part. As a result, an initial fitting resistance is generated. (2) When the locking projection portion is forced forward against the initial resistance, the front portion of the female fitting part expands outward elastically, with a small resistance being applied thereto. (3) When the locking projection portion is locked to the locking recess, the front portion of the female fitting part contracts, e.g. returns to the original shape. In a series of the above operations (1) to (3), an operator presses one connector member with a comparatively large force to advance the locking projection toward the locking recess after when the locking projection first contacts the front end of the female fitting part. As a result, the locking projection advances to the locking recess portion with an inertial effect and is locked thereto. At this time, preferably the construction is such that operator senses the completion of fitting, e.g. as a "click". The operator thus knows that the fitting operation is complete. The inertial effect minimizes risk of imperfect connection. As described above the front portion of the female Fitting part expands elastically and the second portion thereof rearward of the front portion is undeformable portion or relatively hard to deform. Thus, when an external force (in particular, bending load) is applied to the female fitting part after the connection between the connector members is completed, the second portion protects the terminal connection. Thus, there is no possibility that the terminal connection is placed out of position, deformed or connected defectively due to external force. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will now be described by way of non-limitative example with reference to the accompanying drawings, in which:- Fig. 1 is a front view half in section showing a connector embodying this invention in a state before a plug-side connector member and a socket-side connector member are connected with each other. Fig. 2 is a front view half in section of the connector members shown in Fig. 1 just before they are fully connected with each other. Fig. 3 is a front view half in section of the connector members shown in Fig. 1 connected with each other. Fig. 4 is a partial enlarged view showing a state immediately before the state shown in Fig. 2. Fig. 5 is a partial enlarged view showing the state shown in Fig. 2. Fig. 6 is a partial enlarged view showing the state shown in Fig. 3. Fig. 7 is a front view half in section showing a known connector described above in a state before a plug-side connector member and a socket-side connector member are connected with each other. Fig. 8 is a front view half in section showing the connector members shown in Fig. 7 connected with each other. Fig. 9 is a diagrammatic view of a building having an array of solar panels with which the connector of the invention may be employed. Fig. 10 is a view of a solar panel including connector members of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to Figs. 1 to 6. The connector for electric connection includes a plug-side connector member C3 having a housing 11 accommodating a plug terminal 13 and a socket-side connector member C4 having a housing 12 accommodating a socket terminal 14. The housing 11 of the plug-side connector member C3 has cylindrical first, second, and third molded parts 15, 16 and 17 formed separately and joined together, with the first part 15 at the side (rear side) where the electric wire (W1) projects, the third part 17 at the front side, and the second part 16 intermediately therebetween. The first and second parts 15, 16 are connected with each other non-removably by fitting them together, and the second and third parts 16, 17 are connected with each other non-removably by fitting them together to form the cylindrical plug-side connector member C3. The first part 15 located at the rear side of the housing 11 serves for sealing and is made of an elastic material (typically, rubber) and is in close contact with the peripheral surface of the electric wire (W1) to make the member C3 water-proof. The third part 17 is also made of a resiliently deformable (elastic) material such as rubber, preferably a rubber, such as silicone rubber, which does not suffer "creep" when subjected to stress. The second part 16 is formed of a relatively rigid synthetic plastics material such as modified PPE (polyphenylene ether), modified PPO (polyphenylene oxide), PPS (polyphenylene sulfide), UP (unsaturated polyester) which can be suitably used in a connector to constitute a component part of a solar-energy power generation system. These plastics materials are weather resistant, hydrolysis resistant, and fire-retardant, comparatively hard, and have a low degree of elasticity. In normal use, the part 17 is not deformed. The female fitting part 18 of the connector member C3 is formed of the third part 17 and the front half of the second part 16 which overlaps the third part 17. Thus the female fitting part 18 has an elastically expandable/contractible portion 18a formed of elastic material and located at its front side; and a less deformable or undeformable portion 18b formed of a material which is harder than the expandable/contractible portion 18a and difficult to elastically deform located at its rear side. In this female fitting part 18, the male terminal 13 is located. To simplify the drawings, the reference numerals 15, 16 and 17 of the first, second and third parts are not shown in Figs. 2 to 6. A circular locking groove 19 is formed around the entire inner peripheral surface of an intermediate portion of the expandable/contractible portion 18a. As shown enlarged in Figs. 4 to 6, the groove 19 is approximately V-shaped in section, but its surface at its front side is formed perpendicularly or at an angle close to perpendicular to the central axis of the connector. A resistance locking surface 20 (see Figs. 4 to 6) perpendicular or at an angle close to perpendicular to the central axis is formed on the inner peripheral surface of the front end of the expandable/contractible portion 18a. A guide surface 21 (again, see Figs. 4 to 6) tapering outward towards the front end is formed on the outer peripheral side of the resistance locking surface 20. The housing 12 of the socket-side connector member C4 is formed of a first part 22 serving for sealing located at the side where the electric wire (W2) projects (rear side) and a second part 23 at the front side. The first and second parts 22, 23 are non-separably connected with each other by fitting them together to form the cylindrical housing 12. A male fitting part 24 is formed in the front half of the second part 23, and houses the female terminal 14. The first part 22 is made of an elastic material such as rubber to cause the housing 12 to be waterproof. To allow the male fitting part 24 to be sufficiently rigid as to be smoothly inserted into the female fitting part 18 of the connector member C3, similarly to the second part 16 of the plug-side connector member C3 the second part 23 providing the male fitting part 24 is formed of a synthetic plastics material such as PVC or modified PPE which is suitable to allow the connector to constitute a component part of a solar-energy power generation system, is comparatively hard, and has a low degree of elasticity. In normal use of the connector, this part 24 is substantially not deformed. To simplify the drawings, the reference numerals 22 and 23 of the first and second parts are not shown in Figs. 2 to 6. A locking rib 25 which engages in the locking groove 19 of the female fitting part 18 is formed on the outer peripheral surface of the male fitting part 24 close to the rear end thereof. In correspondence to the shape of the groove 19, the rib 25 is V-shaped in section, and the surface at the rear side thereof is formed perpendicularly or at an angle close to perpendicular to the central axis, while the other surface slopes more gently. The outer diameter of the rib 25 is equal to or a little larger than the outer diameter of the groove 19 (diameter of base of the groove 19). A forward-facing stepped annular surface 26 (reference numeral 26 is shown in only Figs. 4 to 6) is formed on the second part 23 at the rear end of the male fitting part 24. When the male fitting part 24 is inserted fully in the female fitting part 18, the resistance locking surface 20 of the female fitting part 18 and the guide surface 21 thereof contact the stepped surface 26. The external peripheral surface 24a at the front end of the male fitting part 24 is formed tapering to its front end so that the male fitting part 24 can easily fit in the female fitting part 18. The outer diameter of the male fitting part 24 at its front end is set a little smaller than the inner diameter of the female fitting part 18. To allow the female fitting part 18 and the male fitting part 24 to contact closely when fitted, the diameter of the male fitting part 24 at its rear end is set equal to or a little larger than the inner diameter of the female fitting part 18. This achieves a seal. In connecting the connector members C3 and C4 with each other, the following actions occur: (1) As shown in Fig. 4, the locking rib 25 engages the resistance locking surface 20. As a result, a resistance to fitting is generated. (2) When the rib 25 is pressed toward the female fitting part 18 against this fitting resistance, the expandable/contractible portion 18a of the female fitting part 18 expands outward elastically, thus receiving the rib 25. As a result, the rib 25 advances, with a small resistance being applied thereto. (3) When the rib 25 is locked into the groove 19, the expandable/contractible portion 18a returns to its original shape, or nearly so. In the operation of connecting the connector members C3 and C4 with each other, the operator presses the members together with a comparatively large force when the locking rib 25 collides with the resistance locking surface 20. As a result, the expandable/contractible portion 18a expands outward. At this time, the male fitting part 24 becomes fully fitted in the female fitting part 18 owing to the inertia generated. Consequently, the advance of the locking projection portion 25 is stopped at the correct position. That is, the male fitting part 24 is capable of fitting in the female fitting part 18 securely by applying a small force to the locking rib 25. There is very low possibility that the male fitting part 24 is not fitted correctly in the female fitting part 18. In a typical connection operation, the advance of the locking rib 25 is stopped, and then the locking rib 25 again advances and is locked to the locking groove 19, thus generating a "click". At this time, the advance of the rib 25 stops and the operator senses the "click", which allows the operator to know that the connection between the plug-side connector member C3 and the socket-side connector member C4 has been completed. Referring to Fig. 6, when the male fitting part 24 fits in the female fitting part 18, the resistance locking surface 20 and the fitting guide surface 21 contact the stepped surface 26, and the external peripheral surface of the male fitting part 24 and the internal surface of the female fitting part 18 become flush and in continuous contact with each other. This state allows the operator to recognize the completion of the connection between the plug-side connector member C3 and the socket side connector member C4. The guide surface 21 serves to guide the ribs 25 toward the inside of the female fitting part 18, during the fitting operation. The female fitting part 18 is not deformed entirely, but only the front portion (expandable/contractible portion 18a) thereof including the groove 19 is elastically deformed. The rear portion (undeformable portion 18b) thereof is hard to deform. Thus, when an external force is applied to the female fitting part 18 after the connection between the connector members C3 and C4 is completed, the non-deformable portion 18b protects the terminal connection region. Thus, there is low risk that the terminal connection region is placed out of position, deformed or connected defectively by the external force. Other embodiments:- (1) In the above-described embodiment, as the locking portion of the female fitting part 18, the locking recess 19 is formed thereon. As the locking portion of the male fitting part 24, the locking projection 25 is formed thereon. But the locking projection portion 25 may be formed on the inner peripheral surface of the female fitting part 18, and the locking recess 19 may be formed on the peripheral surface of the male fitting part 24. Further, a plurality of locking projections 25 and the locking recesses 19 may be formed at a plurality of positions by spacing them at appropriate axial intervals or continuously in the shape of a wave. (2) In the above-described embodiment, only the front portion (expandable/contractible portion 18a) of the female fitting part 18 is constructed as the elastically deformable part. But the entire female fitting part 18 may be formed as the elastically deformable part. The connector for electric connection of the present invention can be preferably used for the electric connection between modules of a solar battery panel and between solar battery panels. But the connector for electric connection of the present invention can be used widely for connections of other electric component parts. The illustrated connector is single-pole, but the invention is applicable to multi-pole connectors. Fig. 9 shows a building 30 having a roof 31 whose exterior face is partly composed of an array of solar ,panels 32. Such solar panels are electrically interconnected, e.g. in series, by connectors of the invention such as shown in Figs. 1 to 6. Fig. 10 shows one solar panel 32 having electrical wires 33 connected into connector members 34. These connector members 34 may both be plug-side members C3 of Figs. 1 to 6 or both socket-side members C4 or one may be a plug-side member C3 and the other a socket-side member C4. Such connectors may also be used for connecting solar panels to exterior circuits. The connector is compact, strong and easy to connect correctly in the confined spaces available in for example a roof.

Claims: An electrical connector comprising: a first and second connector members (C3,C4) each having a housing and a terminal (13,14) accommodated in said housing, one said housing having a female fitting part (18) having an interior fitting surface and an open front end and the other said housing having a male fitting part (24) having an exterior fitting surface and a front end, the male fitting part (24) being adapted to fit into the female fitting part (18) with contact between said interior and exterior fitting surfaces in a connected state of the connector in which the terminals are engaged to effect electrical connection, wherein said male fitting part has on said exterior fitting surface a first locking element (25) and said female fitting part has on said interior fitting surface a second locking element (19), which locking elements interengage, in said connected state, so as to restrain said male and female fitting parts from disconnection, said female fitting part has a front portion (18a) which includes said open front end and said second locking element (19) and is formed of elastic material so as to be resiliently expansible, and said male fitting part (24) is made of material of lower elasticity than said front portion (18a) of said female fitting part, whereby said male fitting part is less deformed than said female fitting part when they are fitted together, characterized in that : said female fitting part has a second portion (18b) made from plastics material, located rearwardly with respect to said front portion thereof and providing part of said interior surface, which second portion is of lower elasticity than said front portion (18a) thereof. An electrical connector according to claim 1, wherein said first locking element is a locking projection (25) on said exterior surface of said male fitting part and said second locking element is a locking recess (19) in said interior surface of said female fitting part, and said female fitting part has at its said front end a contact surface (20) located so as to be engaged by said locking projection when said male fitting part is inserted into said female fitting part so as to provide resistance to the insertion. An electrical connector according to claim 2, wherein said locking projection (25) has a first surface which faces forwardly in the direction of insertion of the male fitting part into the female fitting part and is inclined to said direction of insertion and a second rearwardly facing surface which is located rearwardly of said first surface and is inclined more closely than said first surface to a plane perpendicular to said direction of insertion. An electrical connector according to any one of claims 1 to 3, wherein said male fitting part tapers towards said front end thereof and said interior fitting surface of said female fitting part complementarily tapers away from said open front end thereof. An electrical connector according to any one of claims 1 to 4, in which one said terminal (13) is located in a recess bounded by said interior fitting surface, and the other said terminal (14) is located in a recess in said male fitting part which opens at said front end thereof. Use of an electrical connector according to claim 1, for electrically inter-connecting solar panels.

Inventors: HIGASHIKOZONO MAKOTO, KUWAHARA MASANORI, HIGASHIKOZONO, MAKOTO, KUWAHARA, MASANORI, Higashikozono, Makoto, Sumitomo Wiring Systems,Ltd, Kuwahara, Masanori, Sumitomo Wiring Systems, Ltd
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1999
Main classification: H01R13
IPC codes: H01R13