Locking device for connectors

Abstract: A locking device for a pair of connectors is disclosed which comprises a first connector having an outer wall provided with a protuberance having a rear engaging surface; a second connector having an outer wall provided with a cantilevered locking arm having a front inner surface engaging with the rear engaging surface of the protuberance; and a backlash preventing face for preventing any backlash from generating between the first and second components in engagement. The backlash preventing face is provided on the rear engaging surface and at least partially conforms with a rotational locus formed by the front inner surface of the locking arm when the locking arm pivotally moves.

Description: The present invention relates to a locking device for the locking of a pair of components to be releasably connected with each other, in particular a pair of connectors used for connecting two parts with each other, according to the preamble portion of claim 1. Such locking devices can be used for connectors connecting a wire harness and the like. A locking device of the type mentioned above is already known from US-A-3,933,406 wherein a protrusion having on its back an arcuate ramp surface for engagement with an inner surface of a locking arm is shown. Once the lower edge of the locking arm has passed the top of said protrusion the arcuate ramp and said locking arm are mutually cooperative to forcefully propel the male member into fully assembled relation with female connector member. When the lower edge of the locking arm abuts the top of said protrusion both components of the connector have not reached their final engagement position. For engagement the lower edge of said locking arm slips along the arcuate ramp surface whereby said components are shifted and pressed towards each other due to the energy stored by the elastic deformation of the locking arm. If the amount of energy stored in the locking arm is too little the components will not reach their final engagement position. Another locking device as shown in Fig. 1 is known from Japanese Patent Application Laid-open No. 53-49695. M and F stand for a male connector and a female connector, respectively. A cantilevered locking arm 3 having a locking hole 4 thereon is formed between two slits 2, 2 on a cylindrical outer surface 1 of the connector F. An engaging protuberance 6 is provided on an outer surface 5 of the connector M. A stop 7 is used for protecting the locking arm 3. When both connectors M and F are being fitted or connected together, the leading edge of the locking arm 3 comes in contact with a slant surface 6a at the front part of the protuberance 6, as shown in Fig. 2A. As the arm 3 moves forward, it bends increasingly upward about its fulcrum 3a (Fig. 1). Then, when the locking hole 4 advances past the apex 6b of the protuberance 6, the locking arm 3 is resiliently restored to its natural or unbent state, as shown in Fig. 2B and the inner surface 4a at the front portion of the hole 4 is positioned, facing a rear surface 6c of the protuberance 6. In this state, the two connectors M and F are locked. The letter P indicates the path described by the inner surface 4a at the leading portion of the hole 4 as the locking arm 3 rotates about the fulcrum 3a and is resiliently restored to its initial state. Fig. 3 is a graph showing the relationship between the locking load and the fitting depth (stroke) when the locking arm 3 is locked at the protuberance 6. The locking load f increases with stroke 1 being increased, and reaches a maximum level at a point ℓ₁ where the hole 4 rides over the apex 6b of the protuberance 6, after which it decreases sharply and reaches zero. Because of inertia arising from their locked state, both connectors F and M stop when the stroke reaches a value ℓ₂. In the said known locking device the inner surface 4a and the vertical rear surface 6c of the protuberance 6 come to face each other with the resilient restoration of the locking arm 3 as the hole 4 rides over the apex 6b of the protuberance 6. In this state the connectors are locked, but the existence of a flexion space or undesired idle overstroke for the hole 4 of the arm 3 as indicated by the path P inevitably arises. In other words, this gives rise to an interval or a backlash X (= ℓ₂ - ℓ₁) between the inner surface 4a and the rear surface 6c. Therefore, in the prior art, even if the two connectors F and M are connected together, the interval of X space remains. The connectors F and M are shifted due to vibration of the vehicle and the like, which in turn brings about the generation of undesired noise. In the case of connectors used as terminals, such movement causes wear of the connectors and impairs its conductive capabilities. To effect a smooth locking of the locking arm 3 with the protuberance 6, and to prevent the two connectors F and M from being insufficiently locked, the apex of the protuberance 6 is rounded as indicated by R in Fig. 4. Nevertheless, an interval X' still remains as before, which could not solve the problem of backlash. Accordingly, the object of the present invention is to provide a locking device of the type mentioned at the beginning which allows reliable locking without the occurrence of backlash between the pair of components. In order to achieve this object, there is provided a locking device for a pair of components comprising the features of claim 1. According to the present invention, the locking arm and the engaging protuberance may lock together so that the surface of the locking arm facing towards the rear engagement surface is in contact with or in close proximity to the arcuate rear engagement surface of said protuberance. As a result, the occurence of backlash between the pair of components during lock is prevented, and the generation of unwanted noise, wear of the terminals, and the impairment of the conductive capabilities caused by the movement of the connectors can be eliminated. Preferred embodiments of the invention are set out in the subclaims. The invention and further features and advantages will become more apparent from the following description of preferred embodiment in conjunction with the drawings wherein: Fig. 1 is an exploded perspective view of male and female connectors according to a prior art; Figs. 2A and 2B are partially enlarged cross-sectional views showing a locking operation between a locking arm and an engaging protuberance in the connectors shown in Fig. 1; Fig. 3 is a graph showing a relationship between a fitting stroke and a locking load in the connectors shown in Fig. 1; Fig. 4 is a partially enlarged cross-sectional view showing a locking operation between a locking arm and an engaging protuberance according to the prior art; Fig. 5 is an exploded perspective view of female and male connectors according to an embodiment of the invention; Fig. 6 is a partially enlarged cross-sectional view showing the locked state of a locking arm and an engaging protuberance in the connectors shown in Fig. 1; Figs. 7A to 7B are cross-sectional views showing the pertinent parts of respective variations of the anti-backlash section of the engaging protuberance; Fig. 8 is a partially perspective view showing a cover and box structure with a locking device according to the invention. The invention will first be described with reference to Figs. 5 to 7 showing a preferred embodiment of the invention. Fig. 5 shows a male connector M and a female connector F. A locking arm 12 is provided on the outer wall 11 of a main body 10 of the male connector M. The locking arm 12 has a through hole 13 at its front end portion, and an operating knob 14 at is rear end portion. Both intermediate legs of the locking arm 12 are connected to the outer wall 11 through a base 15. The locking arm 12 is resiliently rotatable upward or downward about the base 15 which serves as a fulcrum. The female connector F has a hood 18 for receiving the main body 10 of the male connector M. A protuberance 19 for engagement with said locking arm 12 protrudes from the outer wall of the hood 18. As shown on an enlarged scale in Fig. 6, the protuberance 19 has a gentle slant front surface 19a and a rear engagement surface 19b integrally formed on its rear. This rear engagement surface 19b is shaped as an arcuate surface Q′ that corresponds to the path Q defined by the inner surface 13a at the front part of the through hole 13 when the locking arm 12 is rotated and displaced in vertical direction about the base 15. The male connector M and female connector F are further made to be waterproof. The front half portion of the locking arm 12 and the main body 10 are encased together in a waterproof hood 16 which also serves as a receptacle for the hood 18. A guide wall 16a and a guide groove 16b are formed on the waterproof hood 16 so as to mate with flanges 20 and 21 to prevent a reverse connector engagement, respectively. The connectors F and M are connected together through a gasket 17. A terminal chamber 10a of the male connector M and a terminal chamber 18a of the female connector F house the female terminal and male terminal, respectively. Each of the terminals is connected to a wire, which is not shown in the illustration. The connection between the male connector M and female connector F is effected in the same manner as shown in Fig. 2A. As the front end portion of the locking arm 12 gradually moves along the slant surface 19a on the front part of the protuberance 19, the arm 12 is bent upward, while rotating about the base 15. When the surface 13a of the through hole 13 rides over the apex 19c of the protuberance 19, the locking arm 12 undergoes elastic restoration and snaps downward. This condition is shown in Fig. 6. The surface 13a comes into contact with the base Q₀' of the arcuate surface Q' of the rear engagement surface 19b, and the connectors F and M become locked. Since the base Q₀' of the arcuate surface Q′ is identified with the path Q, there is no existence of an interval between the locking hole 13 and the engaging protuberance 19, as shown. Therefore, any backlash between the connectors F and M does not occur. Also, a line tangent to the base Q₀' is perpendicular to the outer wall 11 and parallel to the inner surface 13a. As a result, the connectors F and M do not get unlocked even if a force that tends to draw the connectors apart is applied thereto. The connectors become unlocked only when the knob 14 of the arm 12 is pressed downward. Figs. 7A and B show respective variations of the rear engagement surface 19b of the protuberance 19. Fig. 7A shows a rear engagement surface 19b formed with a notch 19d on its lower half portion, while Fig. 7B shows the rear engagement surface 19b with a notch 19d' formed on the upper half portion. When the arcuate surface Q' of the rear engagement surface 19b is formed to match the aforementioned path Q, the same locking effect exhibited by the example shown in Fig. 2 is realized. As described above, in the present invention, the interval between the through hole of the locking arm and the protuberance is eliminated. Consequently, the problem of backlash when connecting and locking the pair of connectors is solved. In turn, the problems of wear of the terminals, impairment of the conductive capability, and generation of unwanted noise are also solved. Further, in waterproof connectors wherein a waterproof gasket is placed between the pair of connectors, the impairment of the water-resistant property due to vibration can also be prevented. Although the invention has been described in the case of connecting two connectors, it is apparent that the invention is not limited thereto or thereby. More specifically, as shown in Fig. 8, the similar locking device as described in conjunction with Figs. 5 to 7B may be applied to a box 31 with cover 30. The locking device similarly includes a locking arm 12' having a locking hole 13' and an associated protuberance 19' to be engaged with the locking hole 13'.

Claims: A locking device for the locking of a pair of components (F,M) to be releasably connected with each other, in particular a pair of connectors used for connecting two parts with each other, said pair of components comprising: a first component (F) having an outer wall provided with a protuberance (19) having a rear engagement surface (19b); a second component (M) having an outer wall (11) provided with a cantilever locking arm (12) having a surface (13a) facing towards said rear engagement surface (19b) for engagement therewith, said engagement surface (19b) facing away from the second component (M); and backlash preventing means for preventing any backlash from generating between said first and second components in engagement, including a substantially arcuate rear engagement surface (19b), characterised in that the rear engagement surface (19b) is shaped such that it coincides with a curved imaginary surface which corresponds to the motion path of the lower edge of said surface (13a) facing towards said rear engagement surface (19b) in an unrestricted pivotal motion of the cantilever locking arm (12) relative to the outer wall (11) of the second component at least at an apex (19c) of the protuberance (19) and at the base (Qo') of the engagement surface (19b) defining the locking position, and that in between the apex (19c) and the base (Qo') the engagement surface (19b) does not extend beyond said curved imaginary surface. Locking device according to claim 1, wherein said locking arm (12) has a through hole (13), on a wall of which said surface (13a) for engaging said rear engagement surface (19b) is formed. Locking device according to claim 1, wherein said rear engagement surface (19b) fully conforms with said curved imaginary surface along its entire length. Locking device according to claim 1, wherein said rear engagement surface (19b) is provided with a cutaway portion between said apex (19c) and said base (Qo').

Inventors: KATO TESTUO, MATSUMOTO MITSURU, TSUJI MASANORI, YAMAMOTO TAKAYUKI, KATO, TESTUO, MATSUMOTO, MITSURU, TSUJI, MASANORI, YAMAMOTO, TAKAYUKI, KATO, TESTUO, C/O YAZAKI PARTS CO., LTD., MATSUMOTO, MITSURU, C/O YAZAKI PARTS CO., LTD., TSUJI, MASANORI, C/O YAZAKI PARTS CO., LTD., YAMAMOTO, TAKAYUKI, C/O YAZAKI PARTS CO., LTD.
Applicants: YAZAKI CORP, YAZAKI CORPORATION
Application year: 1990
Main classification: H01R13
IPC codes: H01R13