Patent Document

RELATED APPLICATIONS 
     The following co-pending and commonly assigned U.S. Patent Application has been filed on the same date as the present application. This application relates to and further describes other aspects of the embodiments disclosed in the present application and is herein incorporated by reference. 
     U.S. pat. application Ser. No. 09/791,419, “ASSEMBLY OF A COMPACT POWER DEVICE”, filed concurrently herewith. 
    
    
     BACKGROUND 
     Mounting surfaces, such as the mounting surface of a rail or molded clip, are commonly used to mount devices. Typically, rails of a common type define a common arrangement for the mounting surface. One type of mounting rail is the “DIN” type standard, also known as a “DIN rail,” as defined by the European Standards DIN EN 50022, “Specification for Low Voltage Switchgear and Control Gear for Industrial Use. Mounting Rails. Top Hat Rails 35 mm Wide for Snap-On Mounting Equipment”. Devices such as programmable logic controllers (“PLC&#39;s”), Remote Terminal Units (“RTU&#39;s”), protection relays, terminal blocks, fault recorders and meters are typically supplied with hardware, integrated or external, which allows the device to mount to DIN rails for installation and use. 
     Meters include watt-hour or revenue meters of the type used by energy suppliers to accurately measure electrical energy delivered to customers for the purposes of billing and/or collecting revenue, and power quality meters having power quality monitoring, detection and reporting capabilities. As mentioned above, these devices are often configured to mount or dismount to standard mounting devices, such as a DIN rail, by means of mounting hardware. This permits multiple devices to be conveniently located in a small area. 
     Known DIN rail hardware is either separately attached to the device or an integral part of the device. In either case, the hardware is typically complex and contains several pieces and moving parts and, as a result, the hardware is often costly to manufacture and, because of the multiple parts, more susceptible to breakage. Accordingly, there is a need for an improved, simplified mounting enclosure that allows the device to be mounted to a DIN rail or other suitable type of mounting surface without adding unnecessary complexity to the device design or manufacture. 
     Further, the tool used to injection mould plastic is typically split into two parts: the core and the cavity. The core and the cavity, when pressed together, have a space that reflects the shape of the part being injection molded. Molten plastic is injected into this space and, upon cooling, when the core and cavity separate the part is removed. It will be appreciated that a complex part having undercuts or blind cavities will require moving parts inside the core or cavity that must retract before the mold core and cavity can be separated. Further, because machine runtime is included in the manufacturing cost of the part, the step of opening and closing the mold can cause significant per-part cost increases if the mold is designed such that moving parts are required in the mold. 
     Molds that require moving parts are typically also more expensive to build and maintain and are further susceptible to breakage and reliability concerns. Other securing components utilized in the molding process known in the art include metallic securing parts incorporated into the mounting portion. These parts are added during the molding or assembly process, such as ultrasonically welding, heat staking or physically including them in the mold before plastic injection. This results in a number of operations that must be completed to produce a final mounting portion or device, thereby increasing the part cost. 
     Thus, there is a need for a reliable, simplified one part, low cost DIN rail mounting feature that can be integrated into a device. There is also a need for an integrated DIN rail mountable device manufactured with a process that contains no moving mold parts. 
     BRIEF SUMMARY 
     The preferred embodiments relate to an apparatus for mounting or dismounting a device on a mounting surface, for example, the mounting surface of a rail, a molded clip or the like. In a preferred embodiment the apparatus contains a retaining mechanism that mounts to standard sized surface such as a DIN rail or other mounting surface including the same dimensions of the DIN rail. However, other dimensions for the mounting surface could be used. The retaining mechanism is designed with a geometry such that the tool used to injection mold the plastic material has no moving parts. The acts involved in injection molding a part are as simply closing the mold, filling the mold, opening the mold and ejecting the part. 
     In particular, the retaining mechanism includes a body. At least a portion of the body is movably positioned adjacent to the mounting surface. The apparatus also includes a locating feature connected with the body. The locating feature includes a first position that maintains a position of the body during a manufacturing operation and a second position that allows the body to move, e.g., between an open position and a closed position after the manufacturing operation has been completed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  illustrates a perspective view of the device mounted to a DIN rail; 
     FIG. 1 b  illustrates a top view of the device mounted to a DIN rail; 
     FIG. 2 illustrates the back view of the base and mounting device; 
     FIG. 3 illustrates a back perspective view of the base and mounting device; 
     FIG. 4 a  illustrates the front view of the mounting device in its manufacturing position; 
     FIG. 4 b  illustrates a perspective view of the mounting device in its manufacturing position; 
     FIG. 4 c  illustrates a front view of the mounting device in its closed position; 
     FIG. 4 d  illustrates a front view of the mounting device in its open position; 
     FIG. 5 illustrates a cross-sectional view A—A of the base and DIN rail in FIG.  2 . 
    
    
     DETAILED DESCRIPTION 
     Preferred embodiments relate to a mounting mechanism for mounting or dismounting a device on a mounting surface, for example, the mounting surface of a rail, molded clip or the like. Designers often are required to design mounting or retaining mechanisms while optimizing the overall combination of cost and reliability of the entire device. The mounting or retaining mechanism could be used to mount an electric meter for sensing electrical parameters from an electric circuit. 
     Referring now to the drawings, FIGS. 1 a  and  1   b  show perspective and top views respectively of a device  100  attached to a mounting surface such as rail  105  or a molded clip in the shape of the rail. In a preferred embodiment, the device  100  is an electric meter and includes a base  101  and a cover  102 , the base being attached to the rail  105 . The base  101  having terminals such as voltage connectors  106   107   108   109   110  and current connectors  120   121   122   123   124   125  inset into the base  101 . Circuitry is included with the base that operates to sense at least one electrical power parameter. An exemplary device  100  is the type 6200, manufactured by Power Measurement Ltd. located in Saanichton, B.C., Canada. In a preferred embodiment the rail is a DIN rail or similar type conforming to the European Standards DIN EN 50022, “Specification for Low Voltage Switchgear and Control Gear for Industrial Use. Mounting Rails. Top Hat Rails 35 mm Wide for Snap-On Mounting Equipment”. 
     FIG. 2 illustrates the back view of the base  101  attached to the DIN rail  105 . A retaining mechanism  210  aids in retaining the base to the DIN rail  105 . Referring now to FIG. 3, the retaining mechanism  210  is shown without the DIN rail in place. In the preferred embodiment the base is injection molded out of plastic, the retaining mechanism  210  being molded as an integral part of the base  101 . In an alternate embodiment the retaining mechanism  210  is manufactured separately from the base  101  and attached during the final assembly process. The base  101  also contains a depression  306  which is operable to receive and retain the DIN rail  105  (not shown) in place. In the preferred embodiment, the depression  306  also contains multiple retaining tabs  313  which aid in holding the DIN rail  105  in place. 
     FIGS. 4 a  and  4   b  show detailed views of the retaining mechanism  210  in the preferred embodiment. As shown in these figures the retaining mechanism  210  is in the manufacturing position. The manufacturing position is the position the retaining mechanism is in when first released from the injection molding machine. The closed position, as shown in FIG. 4 c , has the body  411  of the retaining mechanism  210  displaced away from the depression  306  into a position such that DIN rail may be securely fixed between the retaining mechanism  210  and the base  101 . The open position, as shown in FIG. 4 d , has the body  411  of the retaining mechanism  210  displaced away from the depression  306  into a position such that the tapered surface  414  can pass over the DIN rail. The retaining mechanism  210  is displaced further away from the depression  306  in the open position than the closed position. How the retaining mechanism travels between the positions is described in more detail below. 
     Referring back to FIG. 4 a , the retaining mechanism  210  is preferably a symmetrical part, thus allowing for even wear on the part. A symmetrical part also prohibits jamming by ensuring one-directional motion of the part. Having a symmetrical part is not necessary but excessive wear and fractures may occur due to uneven loading at a particular point on the part if it is not symmetrical or uniform. It can be appreciated that the invention may function in a similar fashion with the retaining mechanism  210  either symmetrical or non-symmetrical. 
     The retaining mechanism  210  comprises a body  411  connected to two flexible arms  416   a    416   b  which extend outwardly from either side of the body  411  and terminate on the base  101  at connection point  428   a    428   b . In the preferred embodiment the flexible arms  416   a    416   b  are “U” shaped in order to conserve space however it can be appreciated by those skilled in the art that an alternate geometry of arms, such as straight arms, can be utilized. Further, in the preferred embodiment the body  411  slides along its longitudinal axis in a plane parallel to the top surface  404 , towards or away from the DIN rail depression  306 . Hereafter, this sliding action will be described as moving vertically. 
     The base  101  contains a body opening  430  which is slightly larger than the shape of the body  411 , and an arm opening  418   a    418   b  which extends on either side of the flexible arms  416   a    416   b  to the connection point  428   a    248   b . In an alternate embodiment the body opening  430  is not necessary, but is a result of the non-moving mold design as described earlier. Similarly the size of the body opening is a result of the non-moving mold design as described earlier. The arm openings  418   a    418   b  are also a result of the non-moving mold design described earlier. 
     The retaining mechanism  210  has a slot  412  at one end, which is utilized to aid in moving the retaining mechanism  210  by the use of a screwdriver or other similar tool. In the preferred embodiment when the retaining mechanism is in the closed position, as shown in FIG. 4 c , the slot  412  is aligned with a recess  403  on the base  101 , thereby allowing the mounting recess to be more easily accessible for movement when the device is mounted. The retaining mechanism  210  also has a tapered surface  414  which aids in the engagement and retaining of the retaining mechanism  210  to the DIN rail. 
     Further, the retaining mechanism includes a guidance projection  420 , e.g., a wall that protrudes outwardly from the edge of the body  411 . In an alternate embodiment, several smaller projections may be used. The guidance projection  420  contains locating features  422  which are shaped as a one way “snap” feature, that allows the body  411  to move vertically to a certain point, but not return the body  411  to its original position. More specifically, the locating features  422  allow the retaining mechanism  210  to move in one direction from the manufacturing position to the closed position, but not move back to the manufacturing position. A complete description of how the retaining mechanism  210  travels between the positions will be described in more detail below. 
     Referring to FIG. 4 c , the top surface  404  of the base  101  contains locating projections  406   a    406   b    408   a    408   b  which are adapted to aid in restricting the movement of the body  411  when the retaining mechanism  210  is in the closed position. FIG. 4 d , which shows the open position, also contains the same features. The two directions of movement that the locating projections  406   a    406   b    408   a    408   b  limit are in a vertical direction, the restriction dependent on the position of the retaining mechanism  210 , and in a direction towards the top surface  404 . 
     Because the body opening  430  is created during the manufacturing process, the retaining mechanism  210  is prevented from moving in the normal direction of pressing into the body opening  430  when the device is either in the closed position or the open position, or in transition between the two positions. The guidance projection, in conjunction with the locating projections, further limit movement in a horizontal direction. 
     In the manufacturing position (FIG. 4 a ) the locating features  422  are positioned vertically below their respective locating projections  406   a    406   b    408   a    408   b . In either the closed or open position (FIG. 4 c  and  4   d ) the locating features  422  are positioned vertically above their respective locating projections  406   a    406   b    408   a    408   b.    
     Referring now to FIG. 5 the base  101  of the device is attached to the DIN rail  105 . FIG. 5 illustrates the retaining mechanism in the closed position. In the preferred embodiment the DIN rail  105 , or other compatible rail, is in a “C” shape geometry with flanges  506   507  extending outwardly from each edge. In a typical installation the face  504  of the DIN rail is attached to a wall or other mounting surface. The base  101  contains a retaining tab  513  ( 313 FIG. 3) which retains the first flanges  507  of the DIN rail  105 . The retaining mechanism  210  also contains a second lip  515  which retains the second flange  506  of the DIN rail. 
     In the preferred embodiment the device is engaged to the DIN rail by locating the first flange  507  of the DIN rail into the retaining tab  513  located on the base  101 . Multiple retaining tabs may be utilized to increase the mechanical stability of the device while mounted on the DIN rail. In the preferred embodiment the retaining mechanism  210  is in the closed position prior to attaching the device to the DIN rail  105 . The base  101  is then pivoted towards the DIN rail  105  about the retaining tab  513 , the second flange  506  contacting the tapered surface  514  of the retaining mechanism and causing the retaining mechanism  210  to displace from the closed position to the open position, which is when the second flange  506  passes the tapered surface  514 . 
     Finally, the flex arms  416   a    416   b  urge the retaining mechanism to retract to the closed position where it retains the second flange  506  of the DIN rail with the second lip  515 . To disengage the device from the DIN rail the retaining mechanism is moved to the open position so the second flange  506  can be released past the tip of the tapered surface  514 . Once the device has been released the retaining mechanism  210  returns to the closed position, but is unable to return to the manufacturing position as the locating features  422  prevent this. 
     It is to be understood that other changes and modifications to the embodiments described above will be apparent to those skilled in the art, and are contemplated. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.

Technology Category: y