System for attaching an inner air deflector to an air deflector cap for electrical machines

Abstract

A system for fastening an inner air deflector of an axial fan of a rotating electrical machine with a fan (2), comprising an inner air deflector (3) which is inserted into concentrically positioned elongated holes (1.1) formed on the deflector cap (1), characterized in that the inner air deflector (3) has a plurality of spaced-apart edges (3.2) around the motor shaft with elongated holes (3.1) through which an assembly of fastening elements (7) and (8) is inserted from the inside of the housing, one of the elements being prevented from rotating by barriers (1.2) positioned around each hole (1.1), the assembly preferably being tightened from the outside of the housing, thereby allowing adjustment of the size of the gap (6) between the outer end of the blades of the fan (2) and the inner part of the inner air deflector (3).

Description

FIELD OF APPLICATIONThe invention relates to a system for fixing an inner air deflector (3) to an air deflector cap (1) for a rotating electric machine, this air deflector being fixed to the air deflector cap (1) by a screw (7) and a nut (8) inserted through slots (3.1) at the edges (3.2) of the inner air deflector (3) and through slots (1.1) on the air deflector cap (1), so that the tightening of the nut-screw arrangement is performed from the outside of the casing and thus an adjustment of the gap (6) between the outer end of the blades of the inner fan (2) and the inner surface of the inner air deflector (3) is achieved in order to minimize the effects of the formation of countercurrently guided air currents in the vicinity of the gap (6).BACKGROUND OF THE INVENTIONElectric machines should keep the operating temperature controlled in order to avoid physical damage and to increase the efficiency during operation. Air cooling systems typically employ a fan positioned within an air deflector cap through which forced convection of air is performed on the machine frame. The greater the air volume flow that flows through the engine, the greater the efficiency of the cooling system. Therefore, all causes of flow resistance such as physical obstacles or generation of unnecessary turbulence should be avoided.At present, the fan is attached to a rear end of the motor shaft (4) already mounted on the engine in a subsequent step, and the inner air deflector is attached to the air deflector cap. Thus, the assembly of the air deflector-cap-fan assembly is performed in separate steps, with the air deflector-cap-inner air deflector assembly being assembled last.However, a gap must remain between the outer end of the inner fan blades and the inner surface of the air deflector to avoid entrainment of the fan blades on the inner surface of the air deflector. This gap must compensate for all assembly tolerances of the mentioned components. If this gap is too large, it may lead to air turbulence at the location; if it is small, physical contact may take place between the fan and the inner surface of the air deflector.In short, the present invention proposes a solution for assembling the system to allow the most suitable positioning of the inner baffle to the fan and thus to allow the assembly of the inner baffle last on the machine after the fan and the air baffle are already assembled on the machine.DESCRIPTION OF THE PRIOR ARTIn the prior art there are documents which provide possible solutions to the problem of positioning.Patent EP 1 462 657 A1 shows a generic system for mounting an axial fan in order to reduce turbulence and counter-current which are present in the gap between the fan blades and the protective element of the air deflector plate. In this invention, the ends of the wings are connected to an earring and then inserted into the air deflector. This reduces the gap and guides the air flow therein. This solution is similar to that described in GB 2 000 477 A for fans for motor vehicles.Document US 7 326 032 B2 shows a further possibility of reducing such a gap which provides a system for filling the inner surface of the air deflector. However, the system is not intended for electric machines, but only for switch fans. Similarly, document US 4 987 985 A describes a possibility to reduce the gap in an automobile fan.In turn, U.S. Patent 4,548,548 describes a ventilation system used to allow air to flow through a heat exchanger. In this system, the blades have a specific format that allows uniform airflow at the fan outlet. The air deflector is constructed in a format that reduces the formation of countercurrent air streams.A fan cover is disclosed in JP H05-29 263 U. JP 2009-153 323 A discloses a fan assembly in which a distance between a cover member and an impeller of a fan is adjustable.Prior to the above teachings, the documents presented provide solutions to minimize the formation of counter-current air streams into the gap between the ends of the fan blades around the inner surface of the air deflector.OBJECT OF THE INVENTIONThe prior art documents provide solutions for minimizing the gap by filling it or by reducing the vibration of the wings, notably by connecting their outer ends.It is therefore an object of the invention to eliminate the disadvantages of the prior art, thus providing a system for mounting the air deflector which enables mounting of the air deflector after installation of the air deflector cap and the axial fan in the engine. This system aligns the inner portion of the air deflector with the outer portion of the fan. The gap between the blades of the fan and the inner air deflector is adjusted so that the losses from air turbulence are minimized.The present invention relates to a new solution consisting in installing the inner baffle after the completion of the assembly of the other components of the electric machine, in particular the fan and its air deflector cap. Thus, flexibility is enabled for better adjustment of the position of the air deflector relative to the fan.Another advantage of this new system is installation and removal of the air deflector-air deflector cap assembly without requiring special tools or other internal bolts to lock nuts during fan or air deflector maintenance.In order to enable this, a system for fastening the fan baffle-cap assembly has been developed which allows tightening the fastening elements and adjusting their position from the outside of the machine. In this way, the position of the parts can be adjusted with the already mounted but not fully fastened mounting arrangement.DESCRIPTION OF THE INVENTIONThe present invention relates to a system for fixing an inner baffle (3) fixed to an air deflector cap (1) for electric motors provided with a fan (2) to allow adjustment of a gap (6) formed between the ends of the blades of the fan (2) and the inner surface of the inner baffle (3).The body of the inner air deflector (3) has, from one to a plurality of edges (3.2), offset slots (3.1) spaced equidistant from one another about the axis of the electric machine.The term elongated holes (1.1) is understood to mean holes which are formed at the edges (3.2) of the air baffle body (3), so that the cap (1) is fastened by fastening elements (7 and 8). The slots can be in various formats that allow this form of attachment.In a first variant, the slot (1.1) has a curved or non-curved rectangular format, one of its two ends allowing the passage of the body of the fastening elements, but not of the respective screw heads. FIG. 5 shows an unbent elongated hole 5 with one end, which allows the passage of a hexagonal nut (8) or a hexagonal screw head (7).In a second variant (FIG. 10 ), the slot has a rectangular format, the shorter sides of which are semicircular.In a third variant, the slot of the second variant is rotated through 90°.Other similar formats may be implemented with the same concept.Preferably, an air baffle body (3) with three wheels (3.2) offset by 120°, in which the slots (3.1) are located, which have different shapes according to the embodiment of the fastening system, is used.In the air deflector cap (1) there is at least one slot (1.1) or a plurality of them, equidistant or not offset around the axis of the electric machine of different shapes according to the embodiment of the fastening system. Preferably, air deflecting caps (1) are used with three slots offset by 120°, which correspond to the holes of the air deflecting plate (1.1) and thus form an "X".The system consists in fastening the inner air deflector (3) to the air deflector cap (1) by means of preferably hexagonal fastening elements (7) screwed onto hexagonal nuts (8). The fastener set may preferably be a nut and a bolt positioned through the elongated holes of the air deflector cap (3.1) and the holes of the inner air deflector plate (1.1).The tightening of the nut-bolt assembly is performed from the outside of the housing of the rotating electric machine.On the inside of the inner air deflector (3) close to the openings (1.1) are barriers (1.2) which support the fastening elements (7) so that they do not rotate when the nut (8) is tightened from the outside of the housing.In order to uniformly adjust the size (δ) of the gap (6), a spacer is used between the ends of the blades of the inner fan (2) and the inner part of the inner air deflector (3) before final tightening of the nut-bolt assembly (7-8). The spacer is used only in the assembly step.In a first mounting variant, the head of the fastening element (7) is arranged inside the housing, which is blocked by means of holders (1.2). Then, the nut (8) is assembled from the outside. The position of the air deflector is adjusted to be concentric with the inner fan (2) and then the final tightening of the entire assembly is performed.In a second mounting variant, the hexagonal nut ( 8) is introduced inside the air deflector plate. The fastening element (7) is then tightened from the outside of the housing of the machine so that the air deflector (3) can lie concentrically with respect to the inner fan (2).The difference between the two assembly variants is the positioning of the nut (8) and the fastening element (7). In the first variant, the head of the fastening element is arranged inside the housing; in the second variant, it faces the outside.In a third variant, the fastening is carried out by means of a fastening element (7) and a rectangular nut (9), wherein the nut is guided through the openings of the air deflector cap (1.1) and the openings of the inner air deflector plate (1.3). Inside the air deflector body is a barrier (1.2) which prevents the rotation of the nut when the fastener is tightened from the outside of the housing.It should be noted that the aforementioned term (i.e., "nut") is not intended to be limiting or limiting. Other variations are also possible that may include similar elements without departing from the scope of the present invention.It is to be understood that other modifications and variations may occur without departing from the scope of the present invention, which is not limited to the embodiments described hereinabove.BRIEF DESCRIPTION OF THE FIGURESFIG. 1 shows an overview of the electric motor with the installed inner air deflector. FIG. 2 shows a rear view of the electric motor with the inner air deflector installed. FIG. 3 shows the structure of the inner air deflector. FIG. 4 shows a rear view of the electric motor without an inner air deflector. FIG. 5 shows the detail of a possible mounting of the system for fastening the inner air deflector in the electric motor housing, as seen from the inside of the motor. FIGS. 6 and 7 show an assembly of the system for attaching the inner air deflector in the electric motor housing. FIGS. 8 and 9 show a second variant of the assembly of the system for fixing the inner air deflector in the electric motor housing. FIG. 10 shows a third mounting variant of the system for fastening the inner air deflector in the electric motor housing. FIG. 11 is an exploded view of the fastening system detailed in FIG. 10.DETAILED DESCRIPTION OF THE FIGURESFIG. 1 shows an overview of the positioning of the inner air deflector in an electric motor. The inner air deflector (3) is attached to the air deflector cap (1) concentric to the fan (2) which are concentric to the axis of the machine (4). The cover grid of the air deflector cap (5) is positioned concentrically to the axis of the electric motor and is shown in a sectional view in FIG. 1 to mark the position of the fan (2).FIG. 2 is a rear view of the motor whose inner air deflector system installed therein includes the air deflector cap (1), the fan (2), and the inner air deflector (3) without the shroud (5). In this figure, the gap (6) having the thickness (δ) appears marked between the blades of the fan (2) and the inner air deflector (3) after the air deflector has been fastened.FIG. 3 shows the inner air deflector (3) and a possible assembly with three edges (3.2) provided with slots (3.1) which are offset by 120° about the axis of the electric machine.FIG. 4 shows an air deflector cap (1) used in the assembly proposed in FIG. 3 and having three tangential openings (1.1) offset by 120° about the axis of the electric machines, where the inner air deflector (3) shown in FIG. 3 is to be fastened.FIG. 5 shows, from the outside of the engine, the system for fastening the inner air deflector (3) comprising the preferably hexagonal fastening element (7) which is inserted from the inside of the machine housing into the slot (1.1) of the air deflector cap (1) and into the slot (3.1) of the edge (3.2) of the inner air deflector (3), such openings forming an "X". The fastening is carried out by tightening the preferably hexagonal nut (8), so that the size of the gap (6) between the inner air deflector (3) and the outer end of the blade of the inner fan (2) is adjusted after the components have been assembled.FIG. 6 shows the mounting variant shown in FIG. 5 from the inside of the electric machine in a detailed representation, wherein the head of the preferably hexagonal fastening element (7) is supported on the barriers (1.2) positioned in the inner part of the air deflector cap (1) around the elongated hole (1.1), namely in such a manner that the head of the hexagonal fastening element (7) does not rotate during the tightening of the nut (8) from the outside of the housing of the electric machine.Figure 7 shows the rim (3.2) of the inner air deflector (3) fastened by means of the nut-hex bolt arrangement and to the deflector cap (1), as shown in Figures 5 and 6, and viewed from the outside of the engine.FIG. 8 shows a second mounting variant of the system for fastening the inner air deflector (1), wherein the hexagonal nut (8) is inserted into the inner part of the elongated hole of the inner cap (1.1) and supported in the barriers (1.2) with the fastening element inserted from the outside of the housing of the machine. Thus, the difference between the first and second mounting variations is the position of the fastener and the nut.Figure 9 shows the inner air deflector (3) on the air deflector cap (1) fixed by the fixing element provided with hexagonal head (7) and nut (8), as shown in Figure 8, viewed from the outside of the machine.FIG. 10 shows a second mounting variant of the fastening system, wherein a rectangular nut (9) is dimensioned such that it allows passage through the slots of the inner air deflector (3.1) and through the slots of the deflector cap (1.1). Such elongated holes form an "X", so that the rectangular nut (9) is supported by the barrier (1.2) so as to prevent it from rotating from the outside of the electric machine upon the rotation of the fastening element.FIG. 11 shows the exploded view of the fastening element (7)-rectangular nut (9) arrangement, which is inserted into the elongated hole (3.1) of the inner air deflector plate (3) and into the elongated hole (1.1) of the deflector cap (1).

Claims

A system for fastening an inner air deflector of an axial fan of a rotating electric machine with fan (2), comprising an inner air deflector (3) inserted into concentrically positioned slots (1.1) made on the deflector cap (1), characterized in that the inner air deflector (3) has a plurality of spaced apart edges (3.2) with slots (3.1) around the motor shaft, through which an assembly of fastening elements (7) and (8) is inserted from the inside of the casing, one of the elements being prevented from rotating by barriers (1.2) positioned around each hole (1.1), the assembly preferably being attracted to the outside of the casing, thereby, adjustment of the size of the gap (6) between the outer end of the blades of the fan (2) and the inner part of the inner air deflector (3) is made possible.Fastening system according to Claim 1, characterized in that the arrangement with fastening elements consists of preferably hexagonal nuts (8) and screws (7).Fastening system according to one of the preceding claims, characterized in that the hex nut (8) is preferably positioned in the inner part of the housing and the head of the hex screw (7) is mounted in the outer part.Fastening system according to claims 1 to 3, characterised in that the hexagonal nut (8) is preferably positioned in the outer part of the housing and the head of the hexagonal screw (7) is attached in the inner part.Fastening system according to any one of the preceding claims, characterized in that the slot (3.1) has a preferably rectangular shape with rectangular, bevelled or rounded corners, which lies in the tangential direction, one of its ends having a shape that allows the passage of the nut (8) or the head of the fastening element (7).Fastening system according to claim 1 or 2, characterised in that the arrangement of fastening elements preferably consists of a screw and a rectangular nut (8) which are inserted through the slot (1.1) of the deflection cap, wherein the slot mentioned has a barrier in the inner part which prevents the nut from co-rotating when the arrangement of fastening elements is tightened from the outside of the housing.Fastening system according to one of Claims 1, 2 and 6, characterized in that the slot (1.1) of the deflection cap and the slot of the air baffle body (3.1) have a rectangular format with rectangular, beveled or rounded corner points, and are not aligned in the direction of their respective larger regions.Fastening system according to one of Claims 1, 2, 6 and 7, characterized in that the slot (1.1) of the deflection cap (1) lies in the radial direction and the slot of the air baffle body (3.1) lies in the tangential direction.Fastening system according to one of Claims 1, 2, 6 and 7, characterized in that the slot (1.1) of the deflection cap (1) lies in the tangential direction and the slot of the air baffle body (3.1) lies in the radial direction.Fastening system according to one of the preceding claims, characterized in that the cap of the air deflector (3) has up to twelve equally spaced edges (3.2) lying around the motor shaft.Fastening system according to one of the preceding claims, characterized in that the deflection cap of the air deflector (3) has from one to twelve edges (3.2) which are situated around the motor shaft and are not equidistant from one another.

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