Patent Application
20060028075
This application claims benefit of priority to Japanese application No. JP 2004-223968 filed 30th Jul., 2004, the entire contents of which are incorporated by reference herein.
1. Field of the Invention
The present invention relates to a totally hermetically sealed motor for a vehicle that drives for example a railway vehicle, having a totally hermetically sealed construction whereby the atmosphere is not admitted to the interior of the motor.
2. Description of the Related Art
In a railway vehicle such as a train, a motor for vehicle drive is mounted on a chassis that is arranged below the vehicle body and the vehicle is driven by transmitting the torque (turning force or turning effort) of this motor to the wheels through a gear mechanism.
Conventionally, motors of this type are of the open, self-ventilating cooling type, in which cooling is performed by passing external air into the motor by rotation of a ventilation fan that is fixed to the rotor shaft within the motor.
In such an open self-ventilating cooling type motor, a ventilation filter device is provided at the air inlet port in order to prevent the interior of the motor being contaminated by dust mixed with the cooling external air, the dust in the inflowing external air being captured by a filter in the ventilation filter device.
In order to prevent blockage of the filter from causing increased rise in temperature of the motor due to diminution of the inflow of external air, cleaning of the filter must therefore be performed at comparatively short intervals.
However, it is difficult for a filter to capture all the dust, so dust penetrating into the motor gradually adheres and accumulates in the interior of the motor, causing a lowering of installation performance and/or cooling effect. It is therefore necessary to periodically disassemble the motor in order to carry out cleaning to remove the dust in the interior.
The adoption of a motor for vehicle drive of a totally hermetically sealed type has been studied with a view to effecting savings in regard to maintenance of this filter and savings in regard to maintenance by extending the intervals of cleaning of the motor by disassembly.
An example of the construction of a prior art motor for vehicle drive of the totally hermetically sealed type is shown in
A plurality of rotor ventilation holes 9a are provided on a circle at the inner periphery of the rotor core 9. A circulating fan 11 for circulating internal air is mounted in the interior of the motor on the rotor shaft 8.
Ventilation ports 1a, 1b are provided at both ends of the stator frame 1, coolers c of a construction described below being arranged so as to cover these ventilation ports 1a, 1b and mounted on the stator frame 1 by means of bolts, not shown.
In the coolers c, there are mounted connecting cooling air passages 12, 13 having internal spaces 12a, 13a; the coolers c are provided with pipes 14 so as to link the internal spaces 12a, 13a of the connecting cooling air passages 12, 13; and a large number of cooling fins 15 in the form of thin sheets of for example aluminum material are welded to the outer peripheral surface of the pipes 14.
In the motor construction described above, an arm 1c provided on the stator frame 1 is fixed to a chassis frame 16 by means of bolts and is connected with a gear mechanism (not shown) through a coupling at the end 8a of the rotor shaft that extends outside the motor and the gear mechanism is connected with a vehicle shaft 18 that is unitary with a vehicle wheel 17; in this way, the torque (turning force or turning effort) of the motor is transmitted to the vehicle wheel 17 that rolls along a rail 19.
Next, due to rotation of the circulating fan 11 during motor operation, the internal air within the motor enters the air inlet passage 12a of the cooler from the ventilation port 1a and furthermore flows through ventilation passages 14a, whence it enters an exhaust passage 13a and then flows into the interior of the motor from the ventilation port 1b. The internal air flowing into the interior of the motor returns in the radially inwards direction of the circulating fan 11 by flowing through ventilation holes 9a of the rotor core. In this way, the internal air is circulated within the coolers c and through the interior of the motor.
During motor operation, heat is generated by the stator coil 3 and rotor bars 10a and end ring 10b, thereby elevating the temperature of the various parts within the motor. However, the heated internal air is cooled by the cooling fins 15 when flowing through the ventilation passages 14a within the pipes 14. The internal air which is thus cooled is thereby able to cool all of the various parts within the motor by flowing through the interior of the motor and so can prevent the rise in temperature of the stator coil 3 and the rotor bars 10a exceeding the prescribed values.
The cooling effect of the internal air circulating through the ventilation passages 14a is increased by the fact that the cooling fins 15 are arranged orthogonal to the longitudinal direction of the motor in the same direction as the direction of movement of the vehicle, so the streamlines pass between the cooling fins 15, thereby improving the heat-radiating effect of the cooling fins 15.
Thus, with this construction, cooling of the motor is performed without passing external air into the motor, so the filter of the ventilation filter device becomes unnecessary and contamination of the interior of the motor is totally eliminated. The interval at which periodic disassembly of the motor must be performed can thereby be extended, resulting in laborsaving in regard to maintenance.
However, with a motor for vehicle drive of this totally hermetically sealed construction, there are the following three problems.
The first problem is that, since the cooling fins 15, constituting the coolers c, made of thin sheet such as for example aluminum material, must be joined by welding to the outer peripheral surface of the pipes 14, this large number of cooling fins 15 must be welded on one at a time: this adversely affects mass-production characteristics and involves a large number of manufacturing steps, resulting in increased costs.
The second problem is that a large number of ventilation passages 14a of the pipes 14 are arranged in a condition crowded together in the pipe structure and in addition the structure is partitioned by a large number of cooling fins 15, so dust or scraps of paper or fluff present in the atmosphere tend to adhere thereto, adversely affecting the cooling performance as dust gradually causes blockages between the pipes 14 with lapse of time of use. To avoid this it is therefore necessary to remove such dust or fluff by periodically blasting with compressed air. However, owing to the presence of the intersecting cooling fins 15, it is difficult to thoroughly remove dust etc that has become attached in cavities. For such reasons, in order to remove dust or fluff it is necessary to remove the main motor from the chassis, requiring a large-scale maintenance operation.
The third problem is that ventilation ports 1a, 1b are provided at both ends of the stator frame 1 and cooler comprising connecting cooling air passages and a plurality of pipes and a plurality of cooling fins 15 is mounted by means of bolts on the outer peripheral surface of the stator frame 1 so as to cover the ventilation ports 1a, 1b. In this case, there are slight gaps between the stator frame 1 and the coolers c, which therefore present contact heat resistance. Consequently, the rate of thermal conduction from the stator frame 1 to the coolers c is small. In other words, thermal conduction is poor. Consequently, the coolers c cannot be said to be effective.
Accordingly, one object of the present invention is to provide a novel totally hermetically sealed motor for a vehicle that is suitable for mass production and wherein the number of manufacturing steps can be reduced, saving of maintenance and inspection time can be achieved, and wherein cooling performance is improved.
According to the present invention, the above object can be achieved by the following construction. Specifically, in a totally hermetically sealed motor for a vehicle comprising: a ring-shaped stator core; a modified tubular stator frame that is fixed to the outer peripheral surface of said stator core; and a rotor comprising a circulating fan that is freely rotatably supported by bearing brackets arranged at both ends of the stator frame on the inner peripheral side of the stator core and that circulates air within the motor body that is formed by the stator frame and the bearing brackets formed at the ends in the axial direction thereof; the stator frame comprises: a housing wherein a modified tubular body that is mounted on the outer peripheral surface of the stator core is virtually recessed at a single location in the direction of the rotary axis of the rotor; and a cooling section of increased heat-radiating area compared with the housing and formed with a passage for the airflow generated by the circulating fan, by forming a prescribed gap with respect to the outer peripheral surface of the stator core that is integrally formed with the recess of this housing.
In addition, according to the present invention, the above object can be achieved by the following construction.
Specifically, in a totally hermetically sealed motor for a vehicle, the stator frame comprises: a housing wherein a modified tubular body that is mounted on the outer peripheral surface of the stator core is virtually recessed at two locations in the direction of the rotary axis of the rotor; a cooling section of increased heat-radiating area compared with the housing and formed with a passage for the airflow generated by the circulating fan, by forming a prescribed gap with respect to the outer peripheral surface of the stator core that is integrally formed with the recess of this housing; and a foot for placing on the installation surface and of increased heat-radiating area compared with the housing and formed with a passage for the airflow generated by the circulating fan, by forming a prescribed gap with respect to the outer peripheral surface of the stator core that is integrally formed with the other recess of the housing.
In addition, according to the present invention, the above object can be achieved by the following construction. In a totally hermetically sealed motor for a vehicle comprising: a ring-shaped stator core; a modified tubular stator frame that is fixed to the outer peripheral surface of the stator core; and a rotor comprising a circulating fan that is freely rotatably supported by bearing brackets arranged at both ends of the stator frame on the inner peripheral side of the stator core and that circulates air within the motor body that is formed by the stator frame and the bearing brackets formed at the ends in the axial direction thereof; the stator frame comprises: a housing wherein the modified tubular body that is mounted on the outer peripheral surface of the stator core is recessed at a single location in the direction of the rotary axis of the rotor; and a cooling section wherein a passage for the airflow generated by the circulating fan is formed by forming a prescribed gap with respect to the outer peripheral surface of the stator core and comprising, in this airflow passage, a plurality of heat-radiating fins in the direction coinciding with the direction of the rotary axis of the rotor, and whose two respective ends are joined with a recess of this housing.
In addition, according to the present invention, the above object can be achieved by the following construction.
Specifically, in a totally hermetically sealed motor for a vehicle the stator frame comprises: a housing wherein a modified tubular body that is mounted on the outer peripheral surface of the stator core is recessed at two locations in the direction of the rotary axis of the rotor; a cooling section wherein a passage for the airflow generated by the circulating fan is formed by forming a prescribed gap with respect to the outer peripheral surface of the stator core and comprising, in this airflow passage, a plurality of heat-radiating fins for cooling in the direction coinciding with the direction of the rotary axis of the rotor, and whose two respective ends are joined with one recess of this housing; and a foot wherein a passage for the airflow generated by the circulating fan is formed by forming a prescribed gap with respect to the outer peripheral surface of the stator core and comprising, in this airflow passage, a plurality of heat-radiating fins for cooling in the direction coinciding with the direction of the rotary axis of the rotor, and whose two respective ends are joined with another recess of the housing.
A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to
First of all, an application to which a totally hermetically sealed motor for a vehicle according to the present invention may be applied will be described. An electric motor m according to the present invention is removably mounted on a chassis frame 16 as shown in the side view to a larger scale of
Thus, for example as shown in
In a motor as proposed above, as will be described below, the housing and the cooling section are virtually integrally (or actually integrally) constructed with the stator frame 1.
This will be described below with reference to various embodiments, using the drawings.
A totally hermetically sealed motor according to a first embodiment of the present invention is described with reference to
As shown in
In this regard, for the cooling section in, as an arrangement in which the heat-radiating area is increased compared with that of the housing 1m, a construction could be adopted in which for example a plurality of heat-radiating fins 21 are formed in the direction coinciding with the direction of the rotary axis of the rotor. Also, for the feet 1o, as an arrangement in which the heat-radiating area is increased compared with that of the housing 1m, a construction could be adopted in which for example a plurality of heat-radiating fins 22 are formed in the direction coinciding with the direction of the rotary axis of the rotor.
The stator frame 1 comprising the housing 1m, cooling section in, feet lo and mounting section 1p as described above is integrally formed by casting or extrusion.
The operation of a totally hermetically sealed motor for a vehicle according to this embodiment constructed as above is described below.
As shown in
The internal air flowing within the motor circulates through the ventilation holes 9a of the rotor core in the axial direction through the gap between the outer peripheral surface of the rotor core 9 and the inner peripheral surface of the stator core 2 and returns in the radially inwards direction of the circulating fan.
In this way, during operation, the air within the motor is circulated through the path constituted within the cooler. When the air within the motor circulates through the ventilation passages 23a, the passages 23 absorb heat and furthermore this heat is released to the atmosphere by the heat-radiating fins 20, of which a large number are provided.
With the embodiment described above, the following beneficial effects are obtained.
1) Since, rather than adopting a construction in which a plurality of cooling fins made of thin sheet such as aluminum material or the like are joined by welding to the outer peripheral surface of pipes, as in a prior art motor, a construction is adopted in which a large number of cooling fins 21 are integrally formed by casting or extrusion without needing to employ any form of welding, benefits are obtained in regard to mass-production, the number of manufacturing steps can be reduced, and manufacturing costs can be lowered.
2) Also, during operation, the circulating fan 11 circulates cooling internal air through the passage 23 of the cooling section in and the airflow passages 24 of the feet 1o. Also, the streamlines that are generated while the vehicle is moving flow between the outer peripheral surface of the stator frame 1 and the heat-radiating fins 21, 22, but, since the heat-radiating fins 21, 22 extend in the axial direction, even in the case of operation for a long period, dust or fluff etc cannot easily adhere to the cooling air passages, so the cooling effect of the heat-radiating fins 21, 22 shows no decrease even over many years.
3) Even if, over a long period of use, dust adheres to the surface, since the heat-radiating fins 21, 22 are mounted in the axial direction, this can more easily be removed by cleaning using for example air blasting than in the case of the prior art pipe construction, so the need for a large scale maintenance operation in which cleaning is performed by removing the main motor from the chassis disappears.
4) Since there is no contact thermal resistance between the stator frame 1 and the cooling section and the ventilation ports are provided at both ends of the stator frame 1 so that the ventilation ports are covered, regarding the stator frame 1 and the cooling section there is easy conduction to the cooler, thanks to thermal conduction of the temperature of the stator frame 1; thus an effective cooling section may be said to be provided.
Next, in order to ascertain the cooling effect of the present embodiment, a test of elevation of temperature was conducted using a test motor. In the test of temperature elevation, the test was conducted at the various rated speeds of operation of the motor, an inverter power source being used as the power source and simulating the effect of running of the vehicle using simulated streamlines (about 2 m/s) flowing around the main motor.
The results of the test are shown in
The prior art example described above and an embodiment of the present invention will now be compared.
Firstly, in the prior art pipe construction, the material used for the cooling passages is typically thin sheet steel, but, in order to reduce weight and improve cooling performance, aluminum sheet is sometimes used. However, in the prior art type construction welding of the aluminum sheet is difficult, so in cases where a large number of heat-radiating fins are provided, mass-production characteristics are adversely affected and manufacturing costs were therefore increased.
In contrast, in the case of the embodiment of the present invention, the stator frame 1 is integrally constructed of a housing 1m, cooling section 1n, feet lo and mounting section 1p, so manufacture can be achieved using for example casting or extrusion molding, so production costs can be greatly reduced.
Secondly, in the case of the prior art pipe construction, eddy currents are generated at the pipe inlets, so there was the big problem of inlet loss. However, with the embodiment of the present invention shown in
Consequently, compared with the prior art pipe construction, inlet loss is small and, owing to the tubular shape, the airflow resistance of the passage 23 is small, so the rate of air circulation can be increased, thereby making it possible to improve the cooling performance of the main motor as a whole. Also, although during operation cooling air flows between the heat-radiating fins 20, due to their simple radial shape, even if, over a long period of operation, dust adheres to the surface, since the cooling fins are directed in the outwards direction of the wheels of the vehicle as shown in
Also, by drawing the heat-radiating fins 21, 22 in the axial direction, these can be manufactured in a straightforward fashion in a single step even when they are of complex cross-sectional shape, by a processing method involving extrusion (drawing).
Thirdly, since there is no contact thermal resistance between the stator frame and the cooler, since there is not even a minute gap therebetween, the ventilation ports being provided at both ends of the stator frame 1 so that said ventilation ports are covered, regarding the stator frame and the cooler, there is easy conduction of the temperature of the frame to the cooler by thermal conduction; thus an effective cooling section may be said to be provided.
In
Hereinbelow, when the vehicle shaft 18 is depicted, this configuration is shown.
Next, the construction of a totally hermetically sealed motor for vehicle drive according to a second embodiment of the present invention is described with reference to
In this embodiment, a plurality of heat-absorbing fins 25 are formed along the axial direction of the rotor in positions on the opposite side to the heat-radiating fins 21 within the airflow passage 23 in the interior of the cooling section 1n of the stator frame 1, seen from the axial direction of the motor. Other details are the same as in the case of the first embodiment.
In this case, since the plurality of heat-absorbing fins 25 extend in the axial direction in opposing positions (i.e. positions opposite the heat-radiating fins 21 on the opposite side thereto about the housing 1m as center) cooling performance is improved, due to conduction of heat to the heat-radiating fins 21 by the shortest distance. Further improvement in the cooling performance of the motor can be achieved, since heat can be emitted efficiently to the atmosphere.
Next, a totally hermetically sealed motor for vehicle drive according to a third embodiment of the present invention is described with reference to
In this case, since the plurality of heat-absorbing fins 26 extend in the axial direction of the rotor in the same way as the heat-radiating fins 22, cooling performance is improved, due to conduction of heat to the heat-radiating fins 22 by the shortest distance. Further improvement in the cooling performance of the motor can be achieved, since heat can be emitted efficiently to the atmosphere. In this construction, the airflow passages 23, 24 are arranged at three locations in the circumferential direction as seen from the axial direction of the motor.
Next, the construction of a totally hermetically sealed motor for vehicle drive according to a fourth embodiment of the present invention is described with reference to
By means of such a construction, the channel resistance of the passage can be reduced and cooling performance improved.
Next, a totally hermetically sealed motor for vehicle drive according to a fifth embodiment of the present invention is described with reference to
Next, a totally hermetically sealed motor for vehicle drive according to a sixth embodiment of the present invention is described with reference to
In this way, although there is some loss of the benefits of the embodiments described above, mass-production characteristics are better than in the prior art example and manufacturing costs can be lowered.
Although the embodiments described above were described taking as an example the application of the present invention to a railway vehicle, the invention could of course be applied to an automobile or to any independently mobile device.
Although in the embodiments described above, the case was described in which, in a motor body comprising a stator frame and bearing brackets, the stator frame was virtually or actually recessed in a direction coinciding with the direction of the rotary axis of the rotor, this could be implemented in the same way even if the stator frame were to be virtually or actually recessed in a direction coinciding with a direction orthogonal to the rotary axis of the rotor. Although, in the above embodiments, examples were described in which the stator frame 1 including the cooling section in and feet 1o was formed with three airflow passages 23, 24, depending on the application, four or more of these, or two, could be employed. Employing a minimum of three passages, as in the embodiments described above, has the merit that temperature uniformity of cooling is improved and satisfaction of space requirements can be guaranteed.
With the present invention, a totally hermetically sealed motor for a vehicle can be provided of improved cooling performance, that is suitable for mass production, wherein the number of manufacturing steps can be reduced, and whereby laborsaving in regard to maintenance and inspection can be achieved.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-223968 | Jul 2004 | JP | national |
