Abstract:
A novel enclosure for power electrical components is presented. A generally parallelepiped enclosure has an access cover therefore and a substantially planar plate slidably inserted therein, with the plate mounting a heat generating power electrical component thereon. Top and bottom cable raceways are also provided in the enclosure.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an enclosure for electrical devices and connections. More specifically, the present invention relates to an enclosure for power electrical devices and connections, which are arranged in a modular manner on removable assemblies. 
     BACKGROUND OF THE INVENTION 
     Electrical enclosures and modular assemblies for use therein are known. Such enclosures range from simple closed volumes in which connections can be made to more advanced enclosures which can include backplanes to provide plug-in type connections to modular components active cooling components and/or signal distribution systems. Modular assemblies are also common and include units in programmable logic controllers (PLC&#39;s). I/O type cards, etc. An example of a more complex enclosure for use in the personal computer industry includes plug in modules active cooling and a signal distribution system and is shown in U.S. Pat. No. 5,289,363 to Ferchau, et al. 
     While the more complex enclosures are common for low power and/or signal-type connections electronics and electrical components such systems are less common for power electrical devices and connections. A relatively simple portable power distribution enclosure is shown in U.S. Pat. No. 5,070,429 to Skirpan. An example of a more complex power electrical enclosure is discussed in U.S. Pat. No. 3,949,277 to Yosset. which shows a power distribution cabinet which includes busses and frames to receive modular unfunctional power components. 
     However, none of the enclosures of which the present inventor is aware provide a desired set of features for use with power electrical components and connections. Specifically, power electrical components, such as poly-phase 460V or 575V components or the like, are generally quite large relative to electronic components and are connected by large gauge cabling which electrical codes require to be routed with defined minimum radius curves. This is space consuming within an enclosure and the routing process is typically quite labour intensive. Also, unlike electronic components, power electrical components can be subject to and/or develop strong magnetic fields and the components must be mounted in a mechanically sound manner to prevent undesired movement of the components. 
     Also, many power electrical components generate large amounts of waste heat, which must be transferred out of the enclosure. However, such enclosures are often located in “dirty environments” wherein air which is circulated into and out of the enclosure to cool components therein must be filtered to prevent ingress of undesired materials and these filters require periodic maintenance or replacement to prevent component failure and/or fires. Also, unlike electronic components, power electrical components and connections pose a safety hazard to users and/or service technicians unless unintentional contact is prevented by proper shields and/or insulation. Finally, enclosures for power electrical components and connections are generally quite large, as most commonly the components are mounted to the walls of the enclosure, as is the cabling, requiring large amounts of wall space but making inefficient use of the volume within the enclosure. 
     More specifically, for modular injection molding machines manufactured by the assignee of the present invention, major functional systems such as the injection unit mold clamp, hydraulics or electric motors, controls and/or robotic systems are available as preengineered modules of different capacities and/or sizes. These pre-engineered modules are assembled as necessary to meet a customer&#39;s specifications. Accordingly, the specific power electric and power electronics requirements of a particular configuration are often not known until the machine is assembled to meet a specific customer order. The power and electrical subsystems are custom designed and assembled, in a labour intensive, time consuming and costly fashion, for each new molding machine. As a result, if, for example, a component of the power system fails during testing of the machine, diagnosis of the problem may require the complete removal of the power enclosure cabinet. This can result in expensive delays and shutdowns of the main machinery, and can greatly increase the cost of developing and testing new machines. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a novel power electrical enclosure which obviates or mitigates at least one of the disadvantages of the prior art. It is a further object of the present invention to provide a novel injection molding machine with a power electrical enclosure. 
     According to a first aspect of the present invention, there is provided an enclosure for power electrical components and connections, comprising: 
     a generally parallelepiped enclosure having a front face, a back face, a top and a bottom; 
     at least one cover on said enclosure to allow access to a volume defined therein: 
     at least one substantially planar plate insertable into said enclosure when said cover is open, said plate extending from said front face to said back face and having a surface for the mounting of at least one power electrical component; 
     a cable raceway adjacent each of said top and bottom, each said cable raceway arranged to hold one of a set of power cables and a set of control and signal cables; and 
     a portion of said enclosure adjacent said at least one substantially planar plate having an exposed portion of a wall of said enclosure on which electrical components can be mounted. 
     According to another aspect of the present invention, there is provided an enclosure for power electrical components and connections, comprising: 
     a generally parallelepiped enclosure having a front face, a back face, a top and a bottom; 
     at least one cover on said enclosure to allow access to a volume defined therein; 
     at least one substantially planar plate insertable into said enclosure when said cover is open, said plate extending from said front face to said back face and having a surface for the mounting of at least one power electrical component; 
     a cable raceway adjacent one of said top and bottom, said cable raceway arranged to hold a set of set of control and signal cables; and 
     a portion of said enclosure adjacent said at least one substantially planar plate having an exposed portion of a wall of said enclosure on which electrical components can be mounted. 
     According to another aspect of the present invention, there is provided an enclosure for power electrical components and connections, comprising: 
     a generally parallelepiped enclosure having a front face, a back face, a top and a bottom; 
     at least one cover on said enclosure to allow access to a volume defined therein; 
     a cable raceway adjacent one of said top and bottom, said cable raceway arranged to hold a set of control and signal cables and an air plenum adjacent the other of said top and bottom, said air plenum operating to circulate cooling air within said enclosure and having at least one set of power bus bars enclosed therein; 
     at least one substantially planar plate insertable into said enclosure when said cover is open, said plate extending from said front face to said back face and having a surface for the mounting of at least one power electrical component and a power connection means to receive power from said at least one set of power bus bars in said plenum and said cooling air circulated by said plenum being directed onto said mounting surface when said plate is inserted into said enclosure; and 
     a portion of said enclosure adjacent said at least one substantially planar plate having an exposed portion of a wall of said enclosure on which electrical components can be mounted. 
     According to another aspect of the present invention, there is provided an injection molding machine comprising: 
     an injection unit; 
     a clamp unit for clamping molds; 
     a generally parallelepiped power electrical enclosure having a front face, a back face, a top and a bottom; 
     at least one cover on said enclosure to allow access to a volume defined therein; 
     at least one substantially planar plate insertable into said enclosure when said cover is open, said plate extending from said front face to said back face and having at least one power electrical component mounted to a surface thereof; 
     a cable raceway adjacent each of said top and bottom, each said cable raceway holding one of a set of power cables and a set of control and signal cables; and 
     a portion of said enclosure adjacent said at least one substantially planar plate having an exposed portion of a wall of said enclosure on which electrical components are mounted. 
     The present invention provides a high density enclosure for mounting, interconnecting and providing power and control signals to a plurality of control modules such as PLCs, circuit breakers, and hydraulic pump motors. The enclosure accommodates modular, pre-engineered machine function components, which can be independently pre-assembled and interchanged in a short period of time. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein: 
     FIG. 1 shows a perspective view of the front and top of a prior art power electrical enclosure for use with hydraulic or electric molding machines; 
     FIG. 2 shows a perspective view of the front and top of a power electrical enclosure in accordance with the present invention; 
     FIG. 3 shows a perspective view of the rear and top of the enclosure of FIG. 1; 
     FIG. 4 shows an elevational view of a plate used with the enclosure of FIG. 1 with two electrical power components shown in ghosted line and mounted thereon; 
     FIG. 5 shows an expanded view of the area of FIG. 1 within the circle labelled A; 
     FIG. 6 shows a perspective view of the front and top of a power electrical enclosure in accordance with another embodiment of the present invention; and 
     FIG. 7 shows an injection molding machine in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a prior art electrical enclosure, generally indicated at  2 . The enclosure  2  is comprised of multiple machine functions laid out on a planar surface  6 . Heating functions, for machine heats, can be integrated into doors  10  of enclosure  2  or installed on surface  6 . Power wiring  12  and control wiring  14  are, commonly, in close proximity creating a potential safety hazard. Mold heating functions, which are required when a mold machine is coupled to a hot runner mold, must, generally, be installed in a separate enclosure because of the lack of physical space in standard enclosures. Additional cabling is thus required between the separate cabinets. 
     Heat dissipation can be a problem with the prior art enclosure, where solid state relays generate significant heat. To dissipate the heat, a larger enclosure and/or active cooling systems, such as high volume cooling fans, must normally be provided within enclosure  2 . 
     A transformer, used to step down voltages for the controls and machine heats, is typically located outside the prior art enclosures. Generally, the transformer is of a “potted” type, meaning that it is surrounded in silica. The silica adds significantly to the weight of the transformer, and an overhead crane is generally needed to mount the transformer onto an injection molding machine. 
     A further disadvantage of prior art enclosures is that each component is custom designed for each new machine design. For example, the ultimate enclosure design can depend upon clamp tonnage, mold type and cavitation. 
     An enclosure in accordance with an embodiment of the present invention is indicated generally at  20  in FIGS. 2 and 3. As shown, enclosure  20  is generally of a parallelepiped shape and is divided into three principal portions, first portion  24 , central portion  28  and third portion  32 . Central portion  28  includes a pair of covers, which in a presently preferred embodiment, are doors  36   a ,  36   b , which can be opened and/or removed from central portion  28  to permit free access to the interior thereof. 
     First portion  24  and third portion  32  include access panels  40  and  44 , respectively, which are removably fastened to enclosure  20  by bolts or any other suitable means. First portion  24  is separated from central portion  28  by an interior wall  48  which serves to prevent unintentional or unauthorized access to first portion  24  from within central portion  28 . As illustrated, first portion  24  includes a series of ventilating apertures  30  to allow air from the exterior of enclosure  20  to circulate therein. It is contemplated that first portion  24  can contain un-potted or potted transformers, or other power components or the like to which regular access is not generally required, in a manner which inhibits unintentional or unauthorized access to the power components for safety reasons. Suitable cabling apertures (not shown) are provided through interior wall  48  such that connections can be made between the components within first area  24  and other portions of enclosure  20  as needed. 
     In addition to access panel  44 , third portion  32  includes an end access panel  52  and one or more cable apertures  56 . Third portion  32  can include one or more assemblies, referred to herein as plates  60 , as described in more detail below, upon which electrical components and/or connections are mounted. It is contemplated that third portion  32  will include a mains connection, to introduce an electrical power supply mains into enclosure  20  through cables run through apertures  56 , electrical disconnects and/or main fuses. 
     Central portion  28  is sub-divided into two volumes  64  and  68 . Volume  68  provides access to the interior surface of back wall  72  to allow components like PLC  76  to be mounted thereto. Volume  64  includes a series of upper and lower slide tracks (not shown)in which the upper  69  and lower  70  edges of plates  60  can be inserted allowing a service technician or user to slide plates  60  into or out of enclosure  20 . In a present embodiment, the slide tracks are U-shaped, with the lower slide track containing a series of regularly spaced protrusions of semi-circular cross-section. These protrusions reduce the surface area that plates  60  contact on the lower slide track and allow easier sliding movement. The upper slide track consists of a slot through which the top edge of the plate  60  travels. Both upper and lower slide tracks incorporate a notch near the front end to allow plates  60  to hinge away from enclosure  20  when they are pulled out for inspection or maintenance. In the embodiment of FIGS. 2 and 3 central portion  28  includes six plates  60  and third portion  32  includes one plate  60 . 
     As illustrated, in enclosure  20  power cables  74  are run along the top of the enclosure, over a series of supports  78  and signal, control or other low power cabling  80  is run along the bottom of enclosure  20 . The separation of power cable  74  from cabling  80  reduces the possibility of electronic noise being introduced to cables  80 . While in the illustrated embodiment power cables  74  are run along the top and cabling  80  along the bottom, as will be apparent to those of skill in the art this arrangement can be reversed, if desired. 
     Preferably, low power cabling is connected to plates  60  by suitable standard multi-pin connectors, such those manufactured by the AMP Company. In the embodiment of FIGS. 2 and 3 power cables  74  are directly connected to power electrical components on plates  60  as needed. 
     As shown in FIG. 4, plates  60  are essentially a planar rectangular surface  84  with cross bars  88  to which power electrical components  92  (shown ghosted in the Figure) and/or connectors can be mounted by conventional means. In the present embodiment of the invention, surface  84  and cross bars  88  are formed from mild steel, although it is contemplated that other materials, such as high density plastic or other insulating materials can be employed if desired. 
     Each plate  60  also includes a shield  96  which extends horizontally outward from the plane of surface  84  to prevent unintentional contact with components  92  mounted on plate  60  when it is installed in enclosure  20 . In a present embodiment of the invention. shield  96  is formed of transparent acrylic sheet material to allow a visual inspection of a plate  60  to be performed while plate  60  is installed within enclosure  20 . Shield  96  can also have mounted thereon test points, indicators or other electronic devices which service or maintenance personnel may wish to access without removing plate  60  from enclosure  20 . 
     To prevent unintentional contact between components and connections on different plates  60 , all components and connections are located on a single side of each plate  60  As mentioned above, electrical power cabling is generally of large gauge and there are minimum radii defined in electrical codes for curves in routing such cables. In order to permit the connection of multiple power components on a single plate  60  and to make the necessary connections thereto without undue waste of volume within enclosure  20 , electrical components  92  can be horizontally “staggered” to permit power cabling to be run between surface  84  and components  92  as desired. In FIG. 5, a conventional power electrical component  92   a  is shown mounted to extension plates  100  which are mounted in turn to cross bar  88 . Power cables  74  can thus be routed between crossbar  88  and component  92   a  to be connected to component  92   b.    
     As will be apparent, the arrangement of plates  60  within enclosure  20  makes efficient use of the volume within enclosure. Further, as components and/or connections are arranged in a relatively closely spaced, or “dense”, manner within enclosure  20 , the length of the cables and leads required to interconnect the components within enclosure  20  are often reduced. This can result in reduced manufacturing costs and reduced power losses due to shorter cable runs. 
     As mentioned above, power electrical components can generate significant amounts of heat that typically must be removed from within an enclosure. For example, solid state relays used to control heaters in injection molding machines can produce approximately one watt of waste heat for every ampere of electricity they switch. In the present invention, such components are mounted on plates  60  adjacent the edge  104  which is opposite the edge at which shield  96  is mounted, as best seen in FIG. 3. A heat sink  108  is provided on plate  60  and extends beyond the edge of plate  60  and the components which generate significant amounts of heat are thermally connected to heat sink  108  by any appropriate means. As shown in FIG. 2, rear wall  72  of enclosure  20  is provided with one or more slots  112  of complementary shape and size to heat sink  108  and which are positioned such that when a plate  60  with a heat sink  108  is inserted into enclosure  20 , heat sink  108  extends through slot  112 , filling slot  112  inhibiting ingress of foreign matter into enclosure  20  and preventing human contact with the contents of enclosure  20  through slot  112 . With heat sink  108  being located outside enclosure  20 , a potentially significant amount of waste heat is directly and passively radiated outside of enclosure  20 , reducing the cooling requirements within enclosure  20 . 
     While the above description has focused on the advantages of the present invention with respect to the use with power electrical components and connections, as will be apparent to those of skill in the art, enclosure  20  can, and often will also contain low power control electronics and/or signalling systems, etc. Such low power electronics can be mounted in volume  68  in a conventional manner or can be mounted onto a plate  60 , either in addition to or instead of power electrical components. 
     In a present embodiment of the invention, the cooling of the interior of central portion  28  and third portion  32  is accomplished entirely by two pancake fans  116  and  120  which merely circulate the air within enclosure  20  to average any hot spots. 
     While it is contemplated that in some hotter climates and/or environments additional cooling means may be required, the present embodiment is advantageous in that it does not require the circulation of cooling air between the interior and exterior of enclosure  20 . thus eliminating the requirement for filters, etc. which require maintenance and/or servicing. In fact, when doors  36   a  and  36   b  and access panel  44  are properly closed, central portion  28  and third portion  32  are substantially airtight, inhibiting the ingress of dirt or other undesired substances. 
     As will be apparent to those of skill in the art, the use of plates  60 , which are mounted in a front to back orientation in enclosure  20  allows efficient use of the volume within enclosure  20 . For example, the configuration and equipment illustrated in FIGS. 2 and 3 when mounted in a conventional manner to the interior walls of an enclosure require an enclosure 30% larger than the size of enclosure  20 . 
     It is contemplated that, in some circumstances, first portion  24  or third portion  32  can be omitted from enclosure  20 . For example, if a potted transformer is employed with enclosure  20 , it can be mounted to the exterior of enclosure  20  and its cabling led into the interior of enclosure  20  via one or more suitable cable apertures, thus allowing first portion  24  to be omitted. Similarly, if the mains disconnects and other main power connection equipment is located separately and mains power is supplied to enclosure  20  by one or more mains cables, third portion  32  can be omitted and apertures  56  provided elsewhere on enclosure  20  to receive the mains cables. 
     It is also contemplated that, for locations with reduced access space, sliding type doors can be employed instead of doors  36   a  and  36   b  which otherwise require space through which to swing. 
     FIG. 6 shows another embodiment of the present invention wherein like components to those shown in FIGS. 2 through 5 are indicated by like reference numbers. This enclosure, which is indicated generally at  150 , differs from that shown in FIGS. 2 and 3 as described below. 
     Instead of pancake fans  116  and  120 , fan  154  has been provided in a plenum  158  which runs along the top of center section  28 . Fan  154  draws air from within volume  68  and forces it along plenum  158  where it exits from slots  162  into volume  64 . Second, plates  60 ′ have a planar rectangular surface  84 ′ which is continuous, rather than the cross bar arrangement shown in FIG.  4 . Electrical and power components are mounted to surface  84 ′ in the same manner with plate  60  of FIG.  4 . However, the continuous arrangement of surface  84 ′ serves both as a larger heat sink for the components mounted thereto and as an airflow barrier to direct airflow from slots  162  over the components mounted to surface  84 ′ and to the bottom of volume  64  where it is drawn back to volume  68  by fan  154 . 
     As is also illustrated in FIG. 6, instead of power cables  74 , plenum  158  has a set of electrical bus bars  166  running along its length and into third portion  32  to supply power from a mains connection to plates  60 ′. Specifically, each plate  60 ′ includes a connector  170  which when inserted correctly into enclosure  150 , engages a complementary connector (not shown) which is located below plenum  158  and which is electrically connected to bus bars  166 . Components requiring connections to electrical power are connected to connector  170  and receive the required power from bus bars  166  via connector  170  and the complementary connector. In this manner, a “quick connect” facility is provided for making power connections between plates  60 ′, and components mounted thereon, and the mains supply. It is also contemplated that for configurations of components requiring larger amounts of power, two or more sets of bus bars  166  can be provided in plenum  158 . 
     A suitable connector and complementary connector which is presently employed in enclosure 150 comprise part numbers 109723 and 109719, as sold by NATUS Gmbh and Company, KB, Loebstrasse #12, D-54292, Trier, Germany,. although any other suitable connectors can be employed as will occur to those of skill in the art. 
     Enclosures  20  and  150  are believed to be particularly suitable for use with industrial manufacturing machinery. In particular, FIG. 7 shows an injection molding machine  200  with its power electrical components, connections and low power control electronics in enclosure  20 . In a typical large injection molding machine, such as a 825 ton Moduline™ machine manufactured by the assignee of the present invention, the machine can require a transformer, multiple power supplies for various components, a PLC, electromechanical hydraulic controls and related control circuitry, circuit breakers and interrupters, machine heaters, mold heaters (for a hot runner type machine), robotic and handling systems, a large hydraulic pump motor (100 HP or more) and mains disconnects. 
     In the above-mentioned Moduline™ machines, major functional systems such as the injection unit, mold clamp, hydraulics, controls and/or robotics systems are available as pre-engineered modules of different capacities and/or sizes, which are then assembled as necessary to meet a customer&#39;s specific needs. Accordingly, the specific power electric and electronics requirements of machine  200  are often not known until machine  200  is assembled to meet a specific customer order and the power and electrical subsystems are assembled at that time, in a very labour intensive manner. 
     In contrast, it is contemplated that with the present invention a plate  60  or  60 ′ for each specific electrical power/electronics control function can be pre-manufactured and placed in enclosure  20  or  150  as required for a specific machine  200 . For example a mold heat plate  60  can be pre-manufactured and used when machine  200  is matched with a hot runner type mold. If machine  200  is used with a cold runner type machine, then the mold heat plate can be omitted. Further, plates  60  can be pre-manufactured in different power capacities and/or configurations, for example to accommodate hydraulic pumps of different horsepower. It is also contemplated that a single power supply plate can be pre-manufactured which can provide necessary supply voltages to many components within enclosure  20  or  150 , thus reducing the number of separate components within enclosure  20 . 
     As will be apparent, in such a case once a machine  200  is specified, appropriate pre-manufactured plates  60  or  60 ′ can be selected and assembled with any other necessary components in enclosure  20  or  150  in a relatively cost and time effective manner. Further, as will also be apparent, servicing and/or trouble shooting a machine  200  is simplified as plates  60  or  60 ′, and hence corresponding functional subsystems, can be relatively easily changed. 
     As will be further apparent, the present invention can provide a high density enclosure for mounting, interconnecting and providing power and data to a plurality of control modules such as PLCs, circuit breakers, and hydraulic pump motors. The enclosure accommodates modular, pre-engineered machine function components, which can be independently pre-assembled and interchanged in a short period of time. 
     The present invention has the further advantage that standardized, modular power units, and other machine function components, can be tested outside the enclosure before they are mounted. 
     The standardized and modular nature of the components can also result in a simpler and less costly design, as well as increased ease and speed of assembly and disassembly. Repair of components, or upgrade of control functions, such as PLC&#39;s, can also be simplified since fall shutdown of the machine and rewiring of the components may not be necessary. In addition, by reducing the time that a molding machine is inactive, during upgrade or repair, the injection molding unit may not require purging when the machine is reactivated. This may be particularly important for high volume, precision molding applications such as the molding of information carrier plastic substrates, like compact discs or digital video discs. 
     The above-described embodiments of the invention are intended to be examples of the present invention and alterations and modifications may be effected thereto, by those of skill in the art, without departing from the scope of the invention which is defined solely by the claims appended hereto.