Abstract: A centrifugal blower in a cooling system of an electronic device having non-uniform blade spacing with acceptable balance. The non-uniform blade spacing is determined according to specific repeating sinusoidal patterns to obtain acoustic artifacts that are favorable and balance that is similar to that found with equal fan blade spacing. The fan impeller can include a prime number of fan blades to prevent higher harmonic interaction among noise sources. The perceived sound quality from the fan is improved with essentially no effect on the thermal performance of the fan.

Abstract: An insertion/extraction system and method for a compressor casing and a compressor bundle. The system includes a cradle extending from a first axial end of the compressor casing and configured to provide support for the compressor bundle during insertion, and an extension assembly coupled to a first axial end of the compressor bundle and extending therefrom into the compressor casing during insertion of the compressor bundle into the compressor casing, during extraction of the compressor bundle from the compressor casing, or both. The system further includes a support member that engages the extension assembly and the compressor casing to support the first axial end of the compressor bundle via the extension assembly, the support member configured to allow relative movement between the support member and the extension assembly during insertion of the compressor bundle into the compressor casing, extraction of the compressor bundle from the compressor casing, or both.

Abstract: A compressor includes a shaft assembly including a thrust disk disposed on a main shaft and a housing having a first portion and a second portion, the first and second portions adapted to receive the shaft assembly and enclose the shaft assembly therebetween, wherein the shaft assembly is rotatably disposed within the housing, and wherein at least one of the first portion and the second portion includes a shaft assembly retention feature for receiving the thrust disk to regulate a motion of the shaft assembly.

Abstract: A compressor for a turbocharger is supplied with crank case ventilation (CCV) gases from the engine which is turbocharged. The CCV gases are piped into an inlet of the compressor housing which supports an insert with an MWE structure. The MWE structure comprises an outer wall and an inner wall with a gas flow passage defined between them. At high r.p.m. of the compressor impeller air flows through the passage to provide more air volume to the impeller and at low r.p.m. excess air is bled out of the passage for recirculation. The CCV gases are directed to a position upstream of an inlet to the gas flow passage where they emerge through an outlet which may be defined in the insert. The CCV gases may be supplied to the outlet via a chamber defined between the insert and the compressor housing. The arrangement provides for improved mixing of CCV gases with the incoming air and does not compromise noise reduction.

Abstract: A ventilator includes a body casing having an opening formed in its lower portion and an exhaust port formed on one side; a fan that is provided in the body casing, for sucking indoor air from the opening and exhausting the indoor air from the exhaust port; a resin fan casing that has a suction port and forms an air passage of the fan; a protection frame formed outside the air passage to cover a terminal block provided outside the air passage; a resin terminal block cover that watertightly seals a protection frame opening of a lower portion of the protection frame and is opened and closed; a sheet-metal case that is provided in the protection frame and stores the terminal block; and a sheet-metal terminal block cover that opens and closes a lower opening of the sheet-metal case.

Abstract: A cover disk (1) for a closed rotor of a radial flow machine or diagonal flow machine for defining a flow channel has a wall thickness which has a local maximum along the profile mean line of the meridional cross section of the cover disk between a first front side (2) and a second front side (3) of the cover disk. An outer surface (1.2) of the cover disk remote of the flow channel has in the area of this local maximum a convex curvature with a radius (R2.2) whose ratio (R2.2/D2) to an outer diameter (D2) of the rotor is within a range of 0.05 to 0.5 (0.05<R2.2/D2<0.5).

Abstract: A centrifugal pump is proposed having a pump housing (2) which has an inlet (21) and an outlet (22), a rotor (3) having a front side (31) facing the inlet (21) and a rear side (32) remote from the inlet (21), and wherein the rotor (3) has a first pump wheel (4) having first vanes (41) for the generation of a main flow from the inlet (21) to the outlet (22), wherein a second pump wheel (5) having second vanes (52) and having at least one relief bore (6) is provided at the rotor (3) for the generation of a recirculation flow which is directed from the rear side (32) of the rotor (3) through the at least one relief bore (6) and wherein a partition element (7), which separates the recirculation flow at least partly from the main flow in the region of the second pump wheel (5), is provided between the two pump wheels (4, 5). A method for the compensation of the axial thrust in a centrifugal pump is furthermore proposed.

Abstract: To provide a centrifugal compressor having a high pressure ratio, which can achieve a large flow rate while suppressing a decrease in efficiency, the centrifugal compressor being adapted to compress and discharge a gas, which has been sucked in by rotation of an impeller (10) pivotally supported in a casing (11), mainly by centrifugal force, the inlet radius/outlet radius ratio (R1/R2) of the impeller (10) is set at 0.7?R1/R2?0.85, and the inclination angle (74 ) of a back board portion in a hub (10a) of the impeller (10) is set at 5°?0?15°.

Abstract: The present invention relates to a base design of cooling structure, which includes a base, and a shaft tube disposed on the base to support a spindle of an impeller to rotate therein. The base has at least a groove and the groove is located beyond an outer diameter; the groove design can be employed to effectively prevent the issue of contraction stress caused by difference of cooling time of temperature and to prevent a slanted shaft tube for supporting a stable operation of the spindle of the impeller, thereby avoiding the resulting run-out and noise, making vibration and noise test values of the product comply with a standard value range, reducing the defective rate of the product and prolonging the product lifespan.

Abstract: A flow outlet for a pump includes a pocket section which defines a pocket section diameter. A throat section downstream of the pocket section, the throat section defines a throat section diameter less than the pocket section diameter.

Abstract: A micropump structure including a main body, at least one water room partitioning board, at least one fan propeller and at least one drive unit. The main body has at least one water room, an inlet and an outlet. The inlet and the outlet are disposed on a circumference of the main body in communication with the water room. The water room partitioning board is disposed in the water room to divide the water room into at least one water incoming section and at least one water discharging section. The fan propeller is disposed in the water room. The drive unit is disposed in the main body. By means of the water room partitioning board, the flow guiding efficiency of the micropump is greatly enhanced and the axial height of the micropump is reduced so that the working efficiency is promoted and less room is occupied.

Abstract: A centrifugal compressor discharge or suction nozzle is provided. The centrifugal compressor discharge or suction nozzle includes a side resonator integrally formed in the centrifugal compressor discharge or suction nozzle. Further, a centrifugal compressor discharge or suction nozzle formed as a pipe section piece adapted to be mounted on a centrifugal compressor, includes a side resonator integrated into the pipe section piece. Furthermore, a centrifugal compressor includes the centrifugal compressor discharge or suction nozzle and/or the pipe section piece. Additionally, a centrifugal compressor arrangement includes the centrifugal compressor.

Abstract: A diaphragm assembly of a centrifugal compressor includes a return channel wall having a generally ring-like shape; a vane assembly having a plurality of vanes formed integrally with at least one ring-shaped track having a rail structure extending therefrom; and a diaphragm wall having a generally ring-like shape and at least one groove extending around a circumference thereof. The vane assembly is fixedly coupled to the return channel, thereby forming a return channel assembly. The return channel assembly is coupled to the diaphragm wall by sliding the rail structure into the at least one groove of the diaphragm wall.

Abstract: A vertical wind turbine rotatable on its vertical axis in order to capture the most direct vector of the wind, the vertical wind turbine having a horizontal inlet port in communication with a vertical air shaft within which mounted vertically, a shaft having a plurality of horizontally disposed wind turbine blades, the lower end magnetically floating to reduce friction, the lower portion of the vertical wind turbine shaft in intersecting communication with one or more horizontal shafts having a venturi design so as to draw a partial vacuum or low pressure, enhancing the downward flow of the air in the vertical wind turbine, the vertical wind turbine in communication with a generator for the production of electricity, the vertical wind turbine being rotatably but stationary mounted on a stationary object or fixedly mounted on a vehicle with the inlet port of the vertical wind turbine forwardly facing.

Abstract: A pump impeller for a centrifugal pump The impeller is defined by a shroud rotatable about an axis of rotation At least two pump vanes extend axially from the shroud, each of the vanes configured as a blunted tear drop shape and having an inside wall and an outside wall, the leading edges of which are interconnected by a blunt wall The trailing edges of the inside and outside walls merge together A substantially constant width flow channel is defined between the blunted wall of one vane and a confronting surface defined by an inside wall of the other vane The vanes are tapered in the axial directions by inclining the inside wall of each vane radially outwardly.

Abstract: A centrifugal discharge pump (1) for electric household appliances, of unusual efficiency, comprising: a working chamber which has an intake opening and a delivery opening; an open impeller (10) arranged inside said working chamber and rotatable about a main axis (x) and motor means (5) designed to drive said impeller (10) by means of a transmission shaft (6). The impeller (10) comprises a planar support element (11) integral with the transmission shaft (6), and a plurality of blades (12) projecting from the planar extension of this element; a free space (13) of predefined volume is provided between the blades (12) in order to allow the removal of foreign solids present in the discharge stream.

Abstract: A centrifugal fan includes a plurality of blades, a housing for receiving the blades therein and an air guiding mechanism. The housing includes a top wall and a sidewall around the top wall. The sidewall defines a first air outlet and a second air outlet adjacent and perpendicular to the first air outlet. The air guiding mechanism is located between the first air outlet and the second air outlet. The air guiding mechanism includes an air guiding wall parallel to the second air outlet and an air partition wall extending inwardly from the air guiding wall towards the blades. The first air outlet is defined between the air partition wall and the sidewall. The second air outlet is defined between the air guiding wall and the sidewall of the housing.

Abstract: A radial turbomolecular pump comprising an electrostatically levitated rotor with a high compression ratio and pump speed at a chip-scale level. The levitated rotor can be sandwiched between a stator plate and a driver and multiple concentric rings of microblades can be fabricated on the rotor plate and the stator plate. The center portions of the driver and the base plate include concentric ring electrodes for rotor levitation by electrostatic forces. The space between two concentric rings of microblades forms a groove that is wide enough to receive the microblades from the opposing disk. The stator disk can be fixed and the rotor disk spins such that the rotor microblades move tangentially relative to the stator microblades. The microblades can be tilted at an angle from the tangent, facilitating momentum transfer to gas molecules in the radial direction.

Abstract: According to one embodiment, an electronic apparatus is provided with a housing, a circuit board in the housing, fan blades configured to rotate and blow air in a centrifugal direction, and a casing which contains the fan blades. The casing includes an exhaust port and a cut portion which opens in a centrifugal direction different from a direction in which the exhaust port opens, from a perspective of a rotation center of the fan blades, and into which a part of the circuit board is inserted.

Abstract: A pump apparatus comprising a series of stacked impellers rotating about a common axis, for pumping a viscous fluid mixture upwardly from an underground location. The pump apparatus comprises a generally cylindrical housing having an intake at or near its suction end. A plurality of impellers are mounted in the housing to rotate about a shaft, which each induce flow of the mixture toward the discharge end of the pump. Each impeller has a series of radially outwardly extending vanes, one or more of such vanes having a radially-extending horizontal slot and arranged to generate an upwardly moving column of fluid. Without being limited to the theory of operation, the horizontal slot in the vanes assists in creating laminar flow and reducing turbulent flow.

Abstract: A tangential turbine is adapted for receiving kinetic energy from a flowing fluid and comprises a supporting shroud, a rotating runner having a hub and a plurality of radial blades spaced apart on the hub, and a means for controlling the receiving. In first embodiment the controlling means comprises a plurality of springs each connected with its ends turningly about a connecting axis being between and within the hub and the blade and between limit stops to the hub and fixedly to the blade turnable about the axis to a non-working tangential position. In second embodiment the controlling means comprises the shroud shaped into a caisson and provided with turnable aprons and capable of accommodating the runner in the air and controlling the insertion of the blades into the flow below the shroud.

Abstract: A centrifugal compressor that includes an impeller, a diffuser and a shroud. One of the diffuser and shroud includes a plurality of recesses and the other of the diffuser and shroud includes a plurality of radial vanes. The shroud covers the impeller and diffuser such that each radial vane projects into a respective recess.

Abstract: A modular header body is described for distributing fluid to an individually pumped fluid circuit. The modular header body has a valve to selectively isolate the header body's suction chamber from its volute, which permits a pump motor to be disconnected from the header body while the valve is closed. Each modular header body is constructed so that adjacent header bodies can be connected to each other to form a common suction chamber. Each header body's isolation valve operates independently so that the volute of one header body can be isolated from the common suction chamber without affecting fluid supply to the other header bodies.

Abstract: A compressor casing includes a casing insert with a flexible element in the force flux between the insert wall contour and the outer compressor casing. The flexible element is assembled from a support ring and ribs, wherein the ribs axially in front of the support ring and the ribs axially behind the support ring are arranged in an offset manner in relation to each other. Due to the arrangement of the ribs in an offset manner, the axial force flux between the insert wall contour and the outer compressor casing is deflected twice, and an axially compliant flexible construction is achieved.

Abstract: Disclosed are components covered with a protective coating for use in a molten metal bath (or comparable environment) and devices including such components. The protective coating is preferably a ceramic sleeve adhered to a non-coated component by cement. A component with the protective coating is more resistant to degradation in molten metal than is the component without the coating, and may be manufactured by the process of: (a) placing a mold around a non-coated component, there being a space between the mold and the non-coated component; (b) directing uncured refractory into the space; (c) vibrating one or more of the non-coated component or the mold to assist in the movement of the refractory into the space; and (d) allowing the refractory to cure, thus forming a protected component having a refractory coating surrounding at least part of the non-coated component.

Abstract: An impeller for a fan, which impeller comprises a hub and one or more blades, wherein at least one blade has a radially inner portion which is aerofoil in section and a centrifugal accelerator portion which extends radially outwardly from the aerofoil portion. The aerofoil portion has a greater angle of attack than the accelerator portion.

Abstract: A turbocharger has a turbocharger housing with a bearing housing and at least one impeller housing. The bearing housing and the impeller housing are screwed together by way of a screw anchor connection, and at least one head of an anchor of the screw anchor connection is covered by a cover element.

Abstract: A radial compressor, in particular for a turbo-charger, has a spiral housing and a diffuser. The diffuser is constructed such that a low-pressure region in the area of the transition between the spiral housing and the tongue is at least reduced.

Abstract: A pump assembly that includes a pump housing defining an inlet for receiving fluid to be pumped and an outlet for discharging fluid. A rotatable impeller operatively coupled to a drive motor includes a plurality of vane structures integrally formed with a shroud. Each vane structure includes a curved, axial vane segment extending axially from the shroud. A compound, multi-step auxiliary vane extends transversely from each axial vane segment. The auxiliary vane or wing includes at least first and second sections, with the second section overlying the first section in a staggered configuration such that the trailing edges of the first and second sections are spaced apart to form a step. The second auxiliary vane section includes an axial surface that also forms a working vane surface for the auxiliary vane.

Abstract: A machine designed as a centrifugal compressor is applied as an organic rankine cycle turbine by operating the machine in reverse. In order to accommodate the higher pressures when operating as a turbine, a suitable refrigerant is chosen such that the pressures and temperatures are maintained within established limits. Such an adaptation of existing, relatively inexpensive equipment to an application that may be otherwise uneconomical, allows for the convenient and economical use of energy that would be otherwise lost by waste heat to the atmosphere.

Abstract: A centrifugal fan includes a housing and an impeller. The housing includes a base plate, a side plate extending upwardly from a periphery of the base plate and a concave portion depressed downwardly from a central portion of the base plate. The concave portion includes a bottom wall spaced from the base plate and a side wall interconnects with the base plate. An air inlet is defined in the bottom wall. The impeller includes a hub and a plurality of blades extending radially from the hub. The impeller is rotatably arranged on the bottom wall of the concave portion. A bottom face of each of the blades extends into the concave portion.

Abstract: There is provided a centrifugal compressor having a diffuser structure in which airflow is unlikely to separate from a hub side wall surface on a hub side wall surface downstream side within a diffuser passage. In a centrifugal compressor provided with a diffuser passage 15 for recovering static pressure by slowing down discharged air from an outer circumferential end of an impeller that rotates within a housing 11, a hub side wall surface 15b of the diffuser passage 15 is provided with an inclined plane 20 that approaches toward a shroud side, in a position on a downstream side of a portion parallel with a normal line direction of a section surface of an impeller exit.

Abstract: To obtain an air conditioner having a lower-noise centrifugal fan capable of improving product reliability during transportation and execution properties of installation, with reduced packaging materials in favor of environment. The shape of a blade is formed so that when a blade edge positioned on the downstream side of the blowing direction is designated as a blade rear-edge, the centrifugal fan has a relationship of the outer diameter of the side plate>the outer diameter of the blade rear-edge on the side of a side plate>the outer diameter of the blade rear-edge on the side of a main plate?the outer diameter of the main plate, and the blade rear-edge is located inside of a straight line connecting a connection point between the blade rear-edge and the main plate to a connection point between the blade rear-edge and the side plate relative to the rotation axis of the fan, and the distance between the blade rear edge and the rotation axis increases toward the side plate from the main plate.

Abstract: The present invention relates to a submersible centrifugal pump assembly comprising an impeller suspended in the end of a drive shaft, and driven in rotation relative to an impeller seat which is stationary in normal operation and which defines an axial intake for liquid to be transported by the impeller in rotation. The pump assembly is characterized in that the impeller seat is journalled in a pump housing for limited rotational movements in opposite directions of rotation relative to the pump housing, and in rotation controlled in guide means for limited linear displacements in opposite axial directions relative to the impeller.

Abstract: A method of fabricating a steam turbine nozzle box is provided, wherein the method includes forming an annular chamber defined by a radially outer wall and a radially inner wall and coupling a plurality of inlets in flow communication with the annular chamber such that steam is discharged from each of the plurality of inlets into the chamber at an oblique discharge angle with respect to an inlet axial centerline.

Abstract: A delivery pump for conveying a liquid between a pump inlet and a pump outlet, the pump being constructed as a single-stage centrifugal pump with a radial impeller (2) having a centrifugal construction arranged rotatably in an impeller chamber (6) of a pump casing (1); the impeller being connected to a variable-speed drive motor (5) variable in speed into the five-digit range of revolutions per minute, and the impeller receiving liquid flow centrally, and being provided with radially-extending delivery ducts (3), and at outside impeller diameters of up to 55 mm developing rotational speed-dependent delivery heads of up to 300 m. For use in a process engineering system, the delivery pump is designed for nominal operation in the form of continuous centrifugal pump part-load operation with delivery rates in the range of 0 ml/min to 7000 ml/min; the nominal operation is characterized by a centrifugal pump part-load-specific rotational speed nqTL?0.

Abstract: An air diffuser device suitable for use in an air diffuser system for a centrifugal pump the pump including a pump casing with a pumping chamber therein, an impeller mounted within the pumping chamber for rotation about a rotation axis, the impeller including a front side and a rear side. The air diffuser system comprises one or more passages extending through the impeller from the front side to the rear side, the or each passage having a first opening at the rear side and a second opening at the front side of the impeller.

Abstract: An electronic assembly includes an enclosure including a top cover and a bottom cover, and a thermal module arranged between the top cover and the bottom cover of the enclosure. The thermal module includes a centrifugal blower and a fin assembly arranged in an air outlet of the centrifugal blower. The centrifugal blower includes a top lid defining a first air inlet therein, a bottom plate defining a second air inlet therein, a sidewall disposed between the top lid and the bottom plate, with the air outlet defined in the sidewall, and a rotor disposed in an inner space formed between the top lid, the bottom plate and the sidewall. The bottom plate is separated by a distance from the bottom cover of the enclosure. The bottom plate defines an indent therein so as to widen the distance.

Abstract: A turbine housing of an exhaust gas turbocharger includes an outer casing and a rotor casing which is arranged in the outer casing and includes a tubular neck for engagement in an exhaust pipe to conduct exhaust gas from the neck in a direction of an exhaust flange. The exhaust pipe is hereby coupled to the rotor casing for relative movement there between. A sealing ring is arranged between the neck and the exhaust pipe, wherein the neck has one end provided with at least one outwardly directed projection defined by an outer diameter which is greater than an inner diameter of the sealing ring. Fabrication of the turbine housing is realized by pushing the sealing ring over the neck, and inserting an expanding mandrel into the neck to widen the neck.

Abstract: A modular pump assembly has a volute (16), having a suction chamber (120) and a pressure chamber (122), and a pump stack (14) having at least one stage (86), wherein a modular flange (44) is arranged between the volute (16) and the pump stack (14) and is removably coupled to both the pump stack (14) and the volute (16).

Abstract: A compressor section (100) of a turbocharger (501) or other air boost device is provided that can reduce stall noise. The compressor section has a housing (110) with a blind groove (175, 275) formed therein. The blind groove (175, 275) can be in proximity to a leading edge (155) of at least one of the blades (150) and can straddle the leading edges (155) of the splitter blades (150). The blind groove (175, 275) can be formed by machining and/or casting. The blind groove (175, 275) can have a substantially uniform width and depth, and can circumscribe the impeller (130) to form a continuous annular channel.

Abstract: A turbine includes a stack of substantially parallel disks, the rotation of which causes rotation of a shaft. The disks are separated by peripheral spacers, each peripheral spacer having the shape of an airfoil. Each peripheral spacer defines a chord which is angled radially inward, towards the axis of rotation of the disk. The peripheral spacers are located only in the vicinity of the periphery of the disk. Air, or other fluid, entering the turbine engages the airfoil shaped peripheral spacers, and the flow of air generates lift, and associated drag, causing the energy of the fluid to be more efficiently converted into mechanical, and ultimately, electrical power. The turbine is especially useful in harnessing wind energy for the generation of electric power.

Abstract: Blower housings and methods of manufacture include protrusions and openings in edges thereof providing an interlocking assembly. Reduced manufacturing steps and greater versatility to join different materials and materials of different thickness are provided, without requiring welds and fasteners common to conventional blower housing assemblies.

Abstract: A portable electronic device includes a casing, an electronic component disposed in the casing, and a thermal module for dissipating heat of the electronic component. The thermal module includes a heat pipe, a fin unit, and a transverse fan. The heat pipe includes an evaporating section thermally attached to the electronic component, and a condensing section thermally attached to the fin unit. The transverse fan is arranged in the casing for generating an airflow through the electronic component and the fin unit. The transverse fan includes a rotor, and a sidewall on a floor of the casing and surrounding the rotor. The sidewall defines an air inlet and an air outlet therein. The air outlet faces to the fin unit. The air inlet faces to the electronic component.

Abstract: A centrifugal fan includes a housing and a plurality of blades received in the housing. The housing includes a base wall and a sidewall surrounding the base wall. The sidewall defines a first air outlet and a second air outlet adjacent to the first air outlet. An elongated air guiding plate is located between the first air outlet and the second air outlet. The air guiding plate includes an outer end away from the blades and an inner end adjacent to the blades. A height of the inner end of the air guiding plate in an axial direction of the centrifugal fan is smaller than a height of the outer end of the air guiding plate.

Abstract: A lower end unit of a fuel cell system defines a volute of a pump. The volute may have a reinforcement that is disposed on a working area of the volute.

Abstract: A heat dissipating module includes a rotational member, a stationary member and a driving member. The rotational member meshes with the driving member and has an uneven surface at a side thereof to space to the stationary member. The stationary member has plural flow passages and each flow passage has an air inlet at an end thereof and an air outlet at another end thereof. When the driving member actuates the rotational member to rotate with the fluid, the fluid enters the stationary member via the inlet and gathers at the outlet before being guided outward for concentrating the air and cooling the heat dissipated object.

Abstract: A device for distributing a volatile fluid into a surrounding environment. In one exemplary embodiment, the distribution device includes a dual centrifugal blower having a first blower and a second blower, both of which are driven by a common motor. Additionally, in one exemplary embodiment, substantially identical components may be used to form both the first and second blowers of the dual centrifugal blower, which reduces manufacturing costs. The dual centrifugal blower may be incorporated into air freshener devices having replaceable canisters or cartridges.

Abstract: A casing 10 of a pump has first and second casing elements 20, 30. Each of the casing elements has a mating face and these mating faces are sealingly joined. An interior of the first casing element defines a portion of a chamber 50 in which the impeller is mounted. A first interior portion of the second casing element defines the remaining portion of the impeller chamber, and a second interior portion defines a diffusion chamber 60 that is in fluid communication with the impeller chamber. Fluid entering the casing at a fluid inlet 34 passes into the impeller chamber, where velocity is imparted to the fluid. The velocity-enhanced fluid passes axially into the diffusion chamber, which has an expanding cross-sectional area along its length, to convert the velocity into pressure head, which is achieved increasing by at least one of: the radially-inward width and the axial height.

Abstract: A centrifugal fan includes a casing and a fan cover located on the casing. The casing includes a sidewall defining at least one latching groove. A step is formed in the at least one latching groove. The fan cover includes at least one latching leg corresponding to the at least one latching groove. The at least one latching leg includes a locking portion. The locking portion includes a plurality of wedge-shaped hooks extending latarally and outwardly from the locking portion. The hook has a tapered outer surface for guiding the at least one latching leg to slide into the at least one latching groove and a locking shoulder formed at a topmost portion of the hook. The locking shoulder of the at least one latching leg abuts against the step of the at least one latching groove.