Electrical connector

Abstract: An electrical connector includes a plug connector having a plug shell formed with a flange and a receptacle connector having a receptacle shell provided on its outer circumference with a fitting device. The electrical connector further includes a coupling ring surrounding the plug shell and rotatable and holding the flange of the plug shell. The coupling ring has on its inner circumference a fitting device fitted with the first mentioned fitting device and a flange urging portion for urging the flange, and a key provided between the receptacle shell and the plug shell for preventing relative rotation therebetween. The electrical connector includes at least one wave-shaped annular spring interposed between the flange and the flange urging portion and rotatable together with the coupling ring. The wave-shaped annular ring and the flange are formed in their opposed surfaces with at least one protrusion and at least one recess, respectively, which are detachably fitted with each other, thereby forming a click lock device for causing the protrusion to fall into the recesses to produce click sound when the plug connector and the receptacle connector have been fitted.

Description: This invention relates to an electrical connector to be mounted mainly on a main body, control box or the like of a machine tool, servomotor, robot or the like. Figs. 1a and 1b illustrate a circular connector as one example of hitherto used electrical connectors in a sectional view and a side view seen from the fitting side (on the right side of Fig. 1a) of the connector, respectively. Referring to Fig. 1a, a plug shell 11 is cylindrical and provided on its outer circumferential surface with a key 111 extending in a longitudinal direction on the fitting side. The outer circumferential surface of the plug shell 11 provided with the key 111 is adapted to be fitted in an inner bore of the receptacle shell of a receptacle connector (not shown) mating with this plug shell 11. An insert block 142 having contacts 141 held and fixed thereto is mounted in and fixed to an inner bore 112 of the plug shell 11 by means of an annular anchoring spring 143. Fig. 1a illustrates only two contacts 141 on the sectional plane of the drawing and other contacts are not shown. These contacts 141 are adapted to contact mating contacts (usually socket contacts) provided in the receptacle connector (not shown) to establish an electric connection. Moreover, the plug shell 11 is provided on the outer circumferential surface with a flange 113. A cylindrical coupling ring 12 surrounds the plug shell 11 and is provided on the fitting side (on the right side of the drawing, Fig. la) with fitting means 121 (a single thread screw in this embodiment). This fitting means 121 is adapted to fit with fitting means provided on the receptacle shell of the receptacle connector (not shown). The coupling ring 12 is formed with a circumferential groove 122 in which a retainer ring 13 as a C-shaped washer is fitted. The retainer ring 13 is fixed snugly in the circumferential groove 122 so that the retainer ring 13 does not wobble with any external disturbance. When the coupling ring 12 is fitted in the mating receptacle connector and is being moved toward the receptacle connector, the retainer ring 13 abuts against the rear end of the flange 113 (on the left side of the flange 113 in the drawing) to transmit urging force (thrust) to the flange 113 as a flange urging portion. The flange 113 is accommodated between the retainer ring 13 and a shoulder 123 formed in the coupling ring 12 with some play or clearance. Therefore, the coupling ring 12 is rotatable relative to the plug shell 11 to facilitate the insertion of the plug shell 11 into the mating receptacle connector and the engagement of the fitting means 121 with the fitting means of the receptacle connector. With the coupling ring 12 rotatable when free from the mating receptacle connector in this manner, the threaded engagement of the fitting means can be started by manually rotating the coupling ring 12 relying upon the manual touch of an operator in order to connect the plug and receptacle connectors. Consequently, this arrangement is one advantage for the connectors which are frequently arranged in narrow spaces between appliances. A back shell 15 is a cylindrical cover for protecting connections (on the left ends of the contacts in Fig. la) of electric wires (not shown) connected to the contacts 141. The back shell 15 is integrally fixed to the plug shell 11 with the aid of pipe threads formed on the outer circumference of the rear end (on the left end) of the plug shell 11. In the prior art, a single thread screw having a relatively small pitch has often been used as the fitting means 121 because it is preferable for connectors requiring large thrust. In more detail, there is a relation f α T/P where f is thrust, T is torque to be applied to the coupling ring 12 and P is a pitch of screw. On the other hand, the torque T can be manually set at substantially constant values from 15 kg-cm to 20 kg-cm. Therefore, the smaller the pitch P of screw, the larger is the thrust to be obtained. In connectors, however, a certain length of fitting between the connectors is needed so that the plug shell must be moved forward at least through the fitting length for proper fitting of the connectors. Accordingly, if the pitch of screw is small, the number of rotations of the coupling ring becomes large so that operation of the coupling becomes difficult. In electrical connectors, moreover, there are many cases where the required thrust is not very large depending upon number, configuration and construction of contacts. In such cases, it may be desirable to provide screws having large pitches. If the pitch of a screw is large, the rotating number of a coupling ring becomes advantageously less. However, the screws with large pitches are likely to unscrew due to vibration and the like. Therefore, they encounter a new difficulty of increased chance of disconnection of connectors mating. In connectors, furthermore, it is sufficient to advance a plug shell through a predetermined distance (more than a fitting length) as a design value of the connector and fix it thereat, whereas the completion of the advance of the plug shell through the predetermined distance with the aid of screw can be detected only by change in torque applied to the coupling ring. Therefore, it is not an easy matter to detect whether the coupling ring has been advanced to the fullest extent. Fig. 2 illustrates another example of hitherto used electrical connectors. This connector includes a receptacle connector 1B' having a pin contact a secured to an insulator b, and a plug connector 1A' having a socket contact c provided in an insert aperture e of a base insulator d. In this case, the receptacle connector 1B' is directly connected to the plug connector 1A'. The plug connector 1A' is called a front release connector, whose socket contact c can be disconnected from the pin contact a of the receptacle connector 1B' by operation on the fitting side with the receptacle 1B'. This disconnection will be explained referring to Fig. 2. A cylindrical removing jig (not shown) is inserted through the fitting portion of the receptacle connector 1B' into a clearance between the inner wall of the insert aperture e and the socket contact c so that an anchoring tongue f of the socket contact c is deformed inwardly to disengage from an anchoring step g formed on the inner wall of the insert aperture e. Under this condition, therefore, by pulling a cable h connected to the socket contact c rearward, the socket contact c is removed from the insert aperture e. With the plug connector 1A' of the front release connector, however, an opening of the insert aperture e on the fitting side is formed in a relatively large size for inserting the removing jig thereinto. If the receptacle connector 1B' is fitted in an inclined position with the plug connector 1A', the pin contact a of the receptacle connector 1B' abuts against a tip of the socket contact c to damage it or penetrates into a space between the socket contact c and the inner wall of the insert aperture e. These phenomena detrimentally affect the reliable connection between the receptacle connector 1B' and the plug connector 1A'. This results from the fact that the difference between the inner diameter of the insert aperture e and the outer diameter of the socket contact c is more than twice the thickness of the cylindrical portion of the jig. In order to form an earth circuit for a hitherto used plug connector mounted on a main body of a machine or a control box, one end of a ground connection lead wire is connected together with a protection circuit lead wire to a ground protection circuit terminal provided on the plug connector separately from a signal terminal, and the other end of the ground connection lead wire is connected to the control box or the like by means of connector set screws. In such a prior art, in order to form the earth circuit, the ground connection lead wire is particularly prepared and its end must be clamped to the control box together with a connector. This construction is complicated and difficult to operate. Moreover, as the earth circuit is provided only on the side of a receptacle connector, there is a risk of electric current inadvertently flowing through a worker or so-called electric shock occurring when he connects external contacts to the receptacle connector, while holding the plug connector. Therefore, this arrangement includes a problem concerning protection of human beings. Another locked connector is known from EP-A-0.237.423. It comprises receptacle means having a receptacle shell, coupling means engaging the receptacle means, plug shell means having a lug shell, and back up means and detent means for holding the receptacle means at the plug shell in their fitted position. The detent means comprises a detent ring and spring means for urging the detent ring toward the plug shell. The locked connector is brought into coupling condition by fitting the plug shell into the receptacle shell and subsequently rotating the coupling means in order to complete the movement of the plug shell. Thereby the coupling means of the known connector abuts against the spring means only at a final stage of the coupling movement. It is a primary object of the invention to provide an electrical connector composed of a plug connector and a receptacle connector and including fitting means, for example, screw means relatively rotatable and located between the plug and receptacle connectors, and having a mechanism for preventing the fitting means from loosening even when using screw means of a large pitch and enabling an operator to know completion of fitting of the plug and receptacle connectors. In order to accomplish this object, in an electrical connector including a plug connector and a receptacle connector receiving the plug connector fitted therewith, said receptacle connector including a cylindrical receptacle shell provided on its outer circumference with fitting means rotatable about a fitting axis, said plug connector including a cylindrical plug shell having a portion to be inserted into an inner aperture of said receptacle shell and a flange provided on an outer circumference of the plug shell, said electrical connector further including a cylindrical coupling ring surrounding the outer circumference of the plug shell and rotatable and holding said flange of the plug shell on its forward and rearward sides, said coupling ring having on its inner circumference fitting means fitted with said fitting means provided on the receptacle shell and a flange urging portion for urging said flange on the side opposite to said portion of the plug shell to be inserted with respect to the flange, and key means provided between the inner bore of said receptacle shell and the portion of the plug shell to be inserted into the inner aperture of said receptacle shell for preventing relative rotation between the plug and receptacle shells, the electrical connector according to the invention comprises at least one wave-shaped annular spring interposed between the flange and the flange urging portion, said wave-shaped annular spring being rotatable together with the coupling ring, and said wave-shaped annular ring and the flange being formed in their opposed surfaces with at least one protrusion and at least one recess, respectively, to form a click lock means, these protrusion and the recess being caused to be coincident in position with each other and detachably fitted with each other when said plug connector and said receptacle connector have been fitted, said flange being formed with an annular notch for receiving the wave-shaped annular spring, characterized in that the difference in height between tops and bottoms of wave portions of the wave-shaped annular spring before fitting is larger than the axial length of the annular notch of the flange. In the above arrangement, the term "cylindrical" may be any configuration, so long as they have the constitutions and functions above described. The "fitting means" used herein is intended to include screw threads, bayonet joint, and intermediate means between these means. For example, spiral anchoring steps and protrusions may also be used. The wave-shaped annular spring is generally preferably annular. The wave-shaped annular spring is arranged in the inner bore of the cylindrical coupling ring, and the rear portion of the plug shell extend through the center hole of the wave-shaped annular spring. This spring has wave portions along its circumference and whose amplitudes are in the axial direction of the ring. The larger the amplitude, the smaller is the force required to compress the spring. However, as the spring serves to transmit the thrust by abutting against the flange, it is preferable that the number of wave portions is at least two equally spaced. In many cases, the protrusions are provided on the tops of the wave portions which first abut against the flange. However, the protrusions may be provided at any portions which abut against the flange by the completion of the fitting of the connectors. In Fig. 5a, the protrusion is positioned slightly shifted from the top of the wave portion. These protrusions are detachably fitted in the recesses of the flange. In other word, after fitting, when the coupling ring is again subjected to torque, the protrusions can be removed from the recesses. In this case, the shapes and sizes of the protrusions and recesses and the urging force (compressive force) of the wave-shaped annular spring will determine the force for dislodging the protrusions from the recesses and the loudness and sharpness of the click sound. Moreover, the wave-shaped annular spring is not necessarily completely annular, but may be, for example, polygonal as hexagonal, octagonal or the like or C-shaped which is formed by removing a part from a circle. It is another object of the invention to provide a front release connector whose contacts are connected with a great reliability without wobbling of tip ends of the contacts during connecting operation. For this object, a preferred embodiment of the electrical connector includes a base insulator having at least one contact insert aperture and a contact inserted and anchored at the contact insert aperture, said contact being removed from the contact insert aperture of the base insulator on a connector fitting side, said electrical connector includes a cover insulator detachably secured to the base insulator on the connector fitting side and having a through-hole communicating with said contact insert aperture of the base insulator and having a diameter smaller than than that of the contact insert aperture, thereby enabling said through-hole to guide insertion of the contact. With this arrangement, when the connector is connected to a mating connector, contacts of the mating connector are inserted through the through-apertures of the cover insulator into the piercing apertures of the base insulator. Therefore, the contacts of the mating connector are reliably introduced with their tip ends guided to contacted positions by the through-apertures of the cover insulator. Moreover, when the cover insulator has been removed from the base insulator, a relatively large bore opens through which the contacts can be released through this bore on the fitting side of the connectors. The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings. Figs. 1a and 1b illustrate one example of hitherto used plug connector; Fig. 2 is a sectional view illustrating another prior art connector; Figs. 3a and 3b illustrate a plug connector of one embodiment of the invention; Figs. 4a and 4b illustrate a receptacle connector to be connected to the plug connector shown in Figs. 3a and 3b; Figs. 5a and 5b are views illustrating the operation of the connector of the one embodiment of the invention; Figs. 6a and 6b and 7 illustrate parts used in the embodiment shown in Figs. 3a and 3b and 4a and 4b; Figs. 3a and 3b and 4a and 4b illustrate one embodiment of the connector according to the invention, wherein the like components are designated by the same reference numerals as those in Figs. 1a and 1b. A plug connector shown in Figs. 3a and 3b is similar to that shown in Figs. 1a and 1b with exception that a flange 113 is formed with an annular notch 22 in which a wave-shaped annular spring 21 is arranged. In this embodiment, the plug shell has a diameter slightly smaller than 30 mm and the flange has a diameter of about 38 mm and a thickness of about 4 mm. The flange 113 is formed with the annular notch 22 in its outer circumference on the rear side (on the left side of Fig. 3a). The annular notch 22 has a dimension of approximately 2 mm in radial and axial directions. The wave-shaped annular spring 21 shown in Figs. 6a and 6b is arranged in the annular notch 22. The flange 113 is further formed with recesses 114 (Fig. 5a) on its rear end surface, whose purpose will be explained later. The wave-shaped annular spring 21 is made of a stainless steel having a diameter of about 36 mm and a thickness of about 0.5 mm. The annular spring 21 is deformed to form three wave portions spaced 120° from each other along its circumference. Difference in height between tops and bottoms of the wave portions is about 4 mm. Each of the tops of the wave portions is formed with a protrusions 211 which is a semicircular protrusion having a radius of about 3 mm. Instead of the protrusions 211, recesses may be formed in the wave-shaped annular spring 21, while protrusions may be formed in the flange 113 instead of the recesses 114. The annular spring 21 is further formed at the bottoms of the wave portions with three pawls 212 projecting from the outer circumference of the annular spring 21 for rotating together with the coupling ring 12. Each of the pawls 212 has a width of about 3 mm and a height of about 1.5 mm. The coupling ring 12 is formed in its inner circumference with three longitudinal grooves circumferentially 120° spaced from each other and mating in size with pawls 212 for permitting the wave-shaped annular spring 21 to be inserted into the coupling ring 12. A retainer ring 13 serves as a flange urging portion and is made of a C-shaped stainless steel having a diameter of about 40 mm, a width of about 2 mm and a thickness of about 1 mm. Fig. 7 illustrates the shape of the retainer ring 13. Fitting means 121 is a multiple (three) thread screw and has a pitch of 6 mm which enables the connectors to fit with each other to the fullest extent only by a rotation of 120°. With unified threads (single threads) hitherto used in many cases, as much as three rotations (1080°) are needed to obtain an advanced distance of 6 mm of one connector relative to the mating connector. In this embodiment, when the coupling ring 12 is advanced, the wave-shaped annular spring 21 accommodated in the annular notch 22 of the flange is compressed between the retainer ring 13 and the radially outwardly extending wall of the annular notch 22. In this case, the difference about 4 mm in height between the tops and bottoms of the wave portions of the wave-shaped annular spring is larger than the axially notched distance about 2 mm of the annular notch 22 so that the retainer ring 13 first abuts against the wave-shaped annular spring 21. However, when the coupling ring is further advanced, at a certain instant the retainer ring 13 abuts against the flange 113 so that the advancing force of the coupling ring 12 is directly transmitted to the flange 113 without any action of the wave-shaped annular spring 21. This is the significant effect of this embodiment and makes easy the design of connectors without any risk of the wave-shaped annular spring yielding; in addition it exhibits stable click lock performance. When the coupling ring 12 has been rotated about 120° from the start of fitting of the fitting means, the plug shell 11 has just been inserted into the receptacle shell 31 through approximately 6 mm which is the required fitted length. In this case, it is so constructed that the positions of the protrusions 211 of the wave-shaped annular spring 21 are coincident with the positions of the recesses 114 formed in the radially outward wall of the annular notch 22 of the flange. Therefore, the protrusions 211 detachably fall into the recesses 114, with the result that the coupling ring 12 is slightly prevented from rotating in the loosening direction and the protrusions 211 produce click sound when falling into the recesses 114. Even with the fitting means 121 of the multiple (three) thread screw having the pitch accomplishing the 6 mm advancement only by the rotation of 120°, the coupling ring cannot be unintentionally loosened by the slight prevention of the rotation in the loosening direction. Although the operation of the connector of this embodiment has been clear from the above explanation, it will be explained in more detail hereinafter. In order to connect the coupling ring 12 and the receptacle shell 31, their fitting means are first fitted with each other. The fitting is then started by rotating the coupling ring 12 so that first the coupling ring 12 alone advances toward the receptacle connector 2B. As a result of this, the distance between the flange urging portion of the coupling ring 12 and the flange 113 progressively narrows so that at a certain instant the wave-shaped annular spring 21 interposed therebetween is started to be compressed. In this case, the wave-shaped annular spring 21 is formed with protrusions 211 (they may be recesses as an alternative) in opposition to the rear end surface of the flange, while the wave-shaped annular spring 21 is rotated together with the coupling ring 12. Therefore, the protrusions (or recesses) abut against the end surface of the flange 113 and slidingly move thereon. The coupling ring 12 is further rotated so that the wave-shaped annular spring 21 is further compressed, with the result that the thrust of the coupling ring 12 is directly transmitted to the flange 113. The plug shell 11 is inserted into the receptacle shell 31 in this manner, and at the same time electric contacts held and fixed to inner bores of the shells 11 and 31, respectively, are brought into contact with each other. Fig. 5a schematically illustrates a state of the wave-shaped annular spring 21 before fitting, and Fig. 5b illustrates a state of the spring 21, while the fitting progresses. Moreover, when the fitting of the connector has been completed, the protrusions (or recesses) 211 of the wave-shaped annular spring 21 and the recesses (or protrusions) 114 of the flange 113 are coincident in positions with each other, so that these protrusions and recesses are fitted with each other producing the click sound. In this case, these protrusions and recesses are detachably fitted with each other, and any of the protrusions and recesses are moved together with the coupling ring 12. As a result, the coupling ring 12 is slightly prevented from rotating in the loosening direction at the complete position of fitting. On the other hand, the coupling ring 12 in the plug connector 2A before fitting with the receptacle connector 2B is held by the flange 113 with certain play or clearance but rotatable relative to the flange 113. With this embodiment, as provision is made of the click lock means in which the protrusions fall into the recesses upon completion of the fitting, the following particular effects can be brought about according to the invention. (1) The coupling ring 12 is prevented slightly from rotating in the loosening direction. For example, even if screw threads of large pitch are used for the fitting means 121 and 312, there is no longer any risk of the coupling ring being loosened due to vibrations or the like. Pitches of the screw threads of the fitting means can be freely selected so as to obtain torque of a required value to be applied to the coupling ring 12. (2) An operator can detect the completion of connection of the connectors by the click sound and vibration occurring when the protrusions fall into the recesses with the aid of hand feeling, with consequent less chance of incomplete fitting and overtightening of the fitting means. (3) The click lock means does not detrimentally affect the rotatability of the coupling ring 12 before fitting, maintaining the effect that the fitting can be started relying upon hand feeling when manually rotating the coupling ring 12. While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details can be made therein without departing from the scope of the claims.

Claims: An electrical connector including a plug connector (2A) and a receptacle connector (2B) for receiving the plug connector fitted therewith, said receptacle connector (2B) including a cylindrical receptacle shell (31) provided on its outer circumference with fitting means extending circumferentially about a fitting axis, said plug connector (2A) including a cylindrical plug shell (11) having a portion (142) to be inserted into an inner aperture of said receptacle shell (31) and a flange (113) provided on an outer circumference of the plug shell (11), said electrical connector further including a cylindrical coupling ring (12) surrounding the outer circumference of the plug shell (11) and being rotatable and holding said flange (113) of the shell (11) on its forward and rearward sides, said coupling ring (12) having on its inner circumference fitting means fitted with said fitting means provided on the receptacle shell (31) and a flange urging portion (13) for urging said flange (113) on the side opposite to said portion of the plug shell (11) to be inserted with respect to the flange (113), and key means (111) provided between the inner bore of said receptacle shell (31) and the portion (142) of the plug shell (11) to be inserted into the inner aperture of said receptacle shell (31) for preventing relative rotation between the plug (11) and receptacle (31) shells, said electrical connector comprising at least one wave-shaped annular spring (21) interposed between the flange (113) and the flange urging portion (13), said wave-shaped annular spring (21) being rotatable together with the coupling ring (12), and said wave-shaped annular spring (21) and the flange (113) being formed in their opposed surfaces with at least one protrusion (211) and at least one recess (114), respectively, to form a click lock means, these protrusion (211) and recess (114) being caused to be coincident in position with each other and detachably fitted with each other when said plug connector (2A) and said receptacle connector (2B) have been fitted, said flange (113) being formed with an annular notch (22) in its outer circumference on the rear side for receiving the wave-shaped annular spring (21), characterized in that the difference in height between tops and bottoms of wave portions of the wave-shaped annular spring (21) before fitting is larger than the axial length of the annular notch of the flange (113). An electrical connector as set forth in claim 1, wherein said wave-shaped annular spring (21) comprises three wave portions circumferentially spaced about 120°. An electrical connector as set forth in claim 1, wherein said electrical connector includes a base insulator having at least one contact insert aperture and a contact inserted and anchored at the contact insert aperture, said contact being removed from the contact insert aperture of the base insulator on a connector fitting side, and wherein said electrical connector includes a cover insulator detachably secured to the base insulator on the connector fitting side and having a through-hole communicating with said contact insert aperture of the base insulator and having a diameter smaller than that of the contact insert aperture, thereby enabling said through-hole to guide insertion of the contact. An electrical connector as set forth in claim 3, wherein said cover insulator is provided with mounting protrusions for mounting the cover insulator on the base insulator, each of the mounting protrusions being composed of a small diameter pin formed at its end with beveling and a large diameter pin formed at the bottom of the mounting protrusion, thereby detachably securing the cover insulator to the forward surface of the base insulator by press-fitting the mounting protrusions into the base insulator. An electrical connector as set forth in claim 3, wherein said base insulator is formed in its forward surface with mounting portions for mounting the cover insulator, each of the mounting portions being composed of a fitting aperture and grooves formed on both sides of the fitting aperture.

Inventors: HONMA KAZUHIRO, MORITA TAKESHI, NANAO SHINGO, WATANABE KUNIO, HONMA, KAZUHIRO, MORITA, TAKESHI, NANAO, SHINGO, WATANABE, KUNIO, HONMA, KAZUHIRO, C/O DAIICHI DENSHI KOGYO K.K., MORITA, TAKESHI, C/O JAPAN AVIATION ELECT.IND.LTD., NANAO, SHINGO, C/O JAPAN AVIATION ELECT.IND.LTD., WATANABE, KUNIO, C/O DAIICHI DENSHI KOGYO K.K.
Applicants: DAIICHI DENSHI KOGYO, JAPAN AVIATION ELECTRON, DAIICHI DENSHI KOGYO KABUSHIKI KAISHA, JAPAN AVIATION ELECTRONICS INDUSTRY, LIMITED
Application year: 1991
Main classification: H01R13
IPC codes: H01R13