Modularized elongation ring for air outlet in self-ventilated traction motor

An elongation ring adapted for use in a self-ventilated traction motor and for fixed placement between the non-driving end of the motor housing and a motor end shield. The ring has radial air outlet openings placed along its circumference and is adapted to enclose a fan wheel fixed on a motor driving shaft. A traction motor having such an elongation ring is also contemplated. The elongation ring provides a possibility to easily adapt a motor housing to different motor types such as a self-ventilated motor with the ring, or one with forced ventilation without the ring.

FIELD OF THE INVENTION

The invention relates to self ventilated traction motors and more particular to a means to provide ventilation without casting motor housings or end shields with air outlet openings or machining such in the housing or shield after the casting procedure.

BACKGROUND OF THE INVENTION

Motor housings and end shields for self ventilated traction motors are usually cast in one piece. This means that ventilation openings for the airflow through the stator and rotor inside the housing are cast at the same time or have to be machined in the cast housing or end shields afterwards. Furthermore a special longer housing or deeper end shields for self ventilated traction motors has to be cast taking into account the fan wheel width.

The present invention aims to provide a way to flexibly adapt a motor housing to different motor types and configurations and also enable standardisation of end shield design as well as the motor housing.

U.S. Pat. No. 7,091,635 discloses a flywheel arrangement comprising an elongation ring and a motor end shield, the flywheel arrangement being rotatable in relation to a motor housing.

SUMMARY OF THE INVENTION

According to one aspect of the present invention an elongation ring is adapted for use in a self-ventilated traction motor and for fixed placement between the non-driving end of the motor housing and a motor end shield. The ring has radial air outlet openings placed along its circumference and is adapted to enclose a fan wheel fixed on a motor driving shaft.

According to a further embodiment of the present invention the air outlet openings are selectively coverable by cover plates to regulate the air outlet from the motor and protect the fan and the interior of the motor from water splash from the railway track.

According to yet another embodiment of the present invention the elongation ring has a radially inwards protruding ring-formed lip arranged axially inside of the fan wheel, which lip overlaps radially the fan wheel.

According to a further aspect of the present invention a traction motor of self ventilated type comprises a motor housing, a first motor end shield and an elongation ring according to the present invention, fixedly arranged between the non-driving end of said motor housing and said first motor end shield, where the elongation ring is enclosing a fan wheel fixed on a motor driving shaft.

According to yet another embodiment of the present invention the housing has a square, pentagonal, hexagonal or higher shape or irregular shape.

According to a further embodiment of the invention the housing comprises cast boxes arranged on the outer surface of the housing providing areas for machining through holes for letting air, power cables and/or signal wires into the motor.

According to a further embodiment of the invention the cast boxes are placed on the upper portion of the housing.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the invention is described below referring initially toFIG. 1. A self-ventilated traction motor is shown which comprises a cylindrical motor housing1. The motor housing1body is enveloping a rotor and a stator (not shown). Note that the invention also cover other than cylindrical housing geometries such the housing shape can be square, pentagon, hexagon or other shape, even irregular.

The rotor is arranged concentrically on an out-going rotor shaft (not shown) running through the housing1and to which a coupling connected to a gear box (not shown) may be attached, ultimately driving the driving wheels of the vehicle. At the opposite non-driving end of the motor the shaft is furnished with a fan2sucking air from the drive side of the motor through the motor interior and transporting it further to the surroundings through outlet openings4. The outlet openings4are radial openings placed along a circumference of an elongation ring3that is arranged as an elongation fixed to the above-mentioned end of the housing1and is thus enclosing the fan wheel2. On the opposite end of the elongation ring3a motor housing shield5is attached which also include axial outlet openings7used for other cooling arrangements. Thus the elongation ring3may be used with any housing length providing outlet openings4for the ventilation of the motor without making it necessary to cast the housing with such openings or further machining the housing to provide such openings.

The elongation ring is further depicted inFIG. 2showing a sectional view of a part of said elongation ring3, the fan wheel2and the end shield5. The air sucked by the fan wheel2is thus coming from inside the housing. To force the air stream to pass and cool the coil ends of the stator winding the elongation ring3has a radially inwards protruding ring-formed lip6arranged axially inside of the fan wheel2. The lip6overlaps radially the fan wheel2and thus guides the air stream away from the outer rim of the elongation ring3to cool the coil ends and then, because of this overlap, through the fan wheel2rather than to let the air slip out past the outer diameter of the fan wheel2and through the outlet openings of the elongation ring3without passing said coil ends.

On the motor housing1envelope surface are also cast boxes8arranged. Their purpose is to provide possibilities to arrange air intakes or power cable or signal wire entries to the inner of the housing for connecting cables to the stator. By arranging several boxes8on the surface in different positions it will be possible to adapt the housing1to several different motor types machining through holes in the boxes8suited for the particular chosen condition. By arranging such boxes on the upper portion of the housing it is possible to avoid splashing of water and dirt from the rails.

The opposite driving end of the motor housing1is covered by a second end shield9fastened to the housing1and having a central through hole through which the driving motor shaft is arranged. This second end shield may also be equipped with air inlet holes which are selectably covered by cover plates in case the air intake flow needs to be varied, i.e. equal axial holes as the shield inFIG. 1displays.

By using a elongation ring3in this manner to lengthen the motor space to house a fan, a standard motor housing may be used for both an open self ventilated motor (with an elongation ring and fan) and an open forced ventilated motor (without an elongation ring and fan). In a forced ventilated design the air is forced into the motor either via the housing or end shield by air duct channels by external fans or the air pressure caused by the train speed and therefore no fan is needed in the motor. In the latter case the end shield on the non-driving end of the motor is attached directly to the end of the motor housing. The motor housing length may also be scaleable with the same diameter to provide motors of different power capacity. In this case the same elongation ring3with fan may be used, which further displays the flexibility of this construction.

Adaptations that has to be made when using the elongation ring3is to have a longer shaft, longer bolts to fasten the end shield5to the housing1letting the bolts run through holes in the elongation ring3.

The elongation ring together with the end shields provides many possibilities to adapt the streaming of the air flow due to the openings4,7. Some openings may be covered by cover plates10to direct the flow in a desired direction. Generally it is not particularly practical to have openings in the bottom of the end shield or elongation ring since this part of the motor is close to the railway track and water and dirt present on the track can be splashed or sucked into the motor interior.

To the person skilled in the art further modifications and variations of the described embodiments are possible.