Claims:WE CLAIM
1. An integrated motor assembly, characterized in that:
a removable fan (1) powered by an external power supply and is mounted on a fan shroud (2); and
an airflow diverter (3), the said diverter (3) is an individual component affixed to a non-drive end (NDE) bracket (4) of the motor,
wherein the air diverter (3) comprises a sealing arrangement with a sensor printed circuit board (7) with a sensor signal wire (8) and a cable gland (9) for fixing O-ring (6) on the motor assembly,
wherein the air diverter (3) focuses air flow towards a housing fin (5) of the motor.
2. The assembly as claimed in claim 1, wherein the sensor signal wire (8) attached with cable gland (9) is fetched out from the motor through the said sealing arrangement.
3. The assembly as claimed in claim 1, wherein a power board (11) is attached to an electronic control unit with a heat sink (12) through which air flow from the fan (1) cools the electronic control unit first and then cools the motor.
4. The assembly as claimed in claim 1, wherein the shroud (2) comprises of a single integrated arrangement that houses a steel guard (14) with screw inserts (13).
5. The assembly as claimed in claim 1, wherein the fan (1) operating condition is controlled by an electronic control unit (ECU) based on the specimen motor winding and casing temperature.
, Description:FIELD OF INVENTION
The present invention relates to motor systems. Specifically, the present invention relates to integrated motor unit assembly with removable fan and airflow diverter. Particularly the present invention relates to speed control of the fan with respect to winding temperature. The present invention further relates to airflow diverter for diverting air to ECU fin and housing fin of the Motor.
BACKGROUND
In conventional electrical machines, fans are commonly used to enhance cooling of the machine, allowing for increased power density over that which can be achieved by the machine without increasing the motor size. Normally cooling fans are shaft mounted and it runs always motor speed. Cooling fans can be shaft mounted or separately attached electric machine.
In general, a totally-sealed type is a commonly used arrangement in any kind of traction motor used in vehicles from the view point of reducing maintenance. With a totally enclosed traction motor having such a configuration which does not allow any water or solid particle entry to the motor inside; therefore, the motor cannot take in outside air for cooling, which means that a measure is needed to make the frame larger and thereby increase the convection/radiation area or the like in order to transfer inner heat to the outside. To avoid the disadvantage of becoming larger, a totally-enclosed traction motor has been proposed that uses a cooling fan as a component that reduces machine size and further helps to extract more power of the motor of the given size. The typical arrangement of shaft mounted fan wherein fan is mounted on the drive shaft which draws air from outside and forced towards the housing thereby the cooling of motor is realized. In this arrangement fan will always run at the motor speed and air flow rate is a function of motor. This kind of cooling arrangement may address some of the operating points, however the operating point such as low speed high torque operation demands more cooling effort which is not possible to realize using existing shaft mounted fan arrangements. Also, an operating point such as high speed, low torque region wherein excessive air flow would persist which would result in an additional drag losses leads to an inefficient system design . These limitations need to be addressed.
Various integrated motor unit with fan are disclosed in prior art, some of them are provided here:
US5763969 discloses a drive integrated type motor system comprising a substantially cylindrical electric motor including a rotor, fan connected to said rotor of the electric motor and generating an air flow, a motor drive and the said fan shroud and said baffle of fan shroud are adapted to divide said air flow from said fan into a plurality of component air flows each having a respective air flow rate.
US7362017 discloses fan that is mounted on the motor shaft and fan runs at the same speed of motor speed and the fan is non-separable. Fan cools the ECU first and then it flows through motor fins/housing.
US10418882 discloses a fan that is mounted inside the housing and some ventilation passages and inlet passages that are provided in the bracket.
US 20150349609 discloses a drive arrangement for fan such motor and drive control whereas the present invention discuss about the focusing of the air flow towards the housing fin with help of air diverter arrangement and housing (shroud).
In the disclosed and conventional arrangements, fan is mounted on the shaft, here air flow rate is the function of rotor speed and it is low at the lesser operating speed of the rotor and vice versa. Higher air flow rate is difficult to realise at the low operating speed and high torque operating condition of the rotor and hence the cooling may not be effective at that operating pointThe present invention addresses the above shortcomings and is very efficient and it discloses a removable fan with air flow diverter.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
OBJECT OF THE PRESENT INVENTION
The main object of the present invention is to provide an integrated motor assembly with removable fan and airflow diverter.
It is one object of the present invention, wherein external powered fan is mounted on the shroud and the said shroud acts as a mechanical mounting arrangement of the fan.
It is one object of the present invention, wherein fan operating condition is controlled by electronic control unit based on the specimen motor winding and casing temperature
It is one another object of the present invention, wherein airflow from the fan is diverted with help of an air diverter.
It is yet another object of the present invention, wherein rotor position sensor printed circuit board is placed inside the diverter with necessary sealing arrangement.
It is yet another object of the present invention, wherein electronic control unit (ECU) is placed in the NDE (non-drive end) of the motor, wherein the air coming from the cooling fan cools the ECU fins first and subsequently cools the motor fins.
It is yet another object of the invention to provide a fan shroud which comprises of a single integrated arrangement that houses a steel guard with screw inserts.
SUMMARY
The main aspect of the present invention is to provide integrated motor assembly characterized in that removable fan and airflow diverter, the said fan is powered by external power supply and is mounted on the shroud, the said diverter is an individual component affixed to non-drive end bracket, further the said diverter comprises sensor printed circuit board with sensor signal wire and cable gland is used for fixing O-ring.
It is one aspect of the present invention, wherein fan operating condition is controlled by electronic control unit based onthe specimenmotor winding and casing temperature.
It is another aspect of the present invention, wherein sensor signal wire attached with cable gland is fetched out from the motor through the said sealing arrangement.
It is even another aspect of the present invention, wherein power board is attached to the electronic control unit with heat sink in which air flow from the fan cools the electronic control unit first and then cools the motor.
Other features and advantages of embodiments will be apparent from the accompanying drawings and from the detailed description that follows.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 illustrates the side view of motor assembly with motor, engine control unit and fan, according to the present invention.
Figure 2a illustrates the front view of fan with shroud, according to the present invention.
Figure 2b illustrates the back view of fan with shroud, according to the present invention.
Figure 3a illustrates the front view of non-drive end bracket, according to the present invention.
Figure 3b illustrates the front view of airflow diverter, according to the present invention.
Figure 3c illustrates the side view of NDE bracket with diverter, according to the present invention.
Figure 4 illustrates the cross-sectional view of arrangement motor unit with fan, according to the present invention.
Figure 5a illustrates the cross-sectional view of arrangement of sensor signal wire and PCB, according to the present invention.
Figure 5b illustrates the front view of NDE bracket with sensor PCB, according to the present invention.
Figure 6a illustrates the cross-sectional view of arrangement of power board and control board of motor assembly arrangement, according to the present invention.
Figure 6b illustrates the side view of motor assembly arrangement with ECU heat sink, power board and control board, according to the present invention.
Figure 7a illustrates the fan cover without guard in the motor assembly arrangement.
Figure 7b illustrates the fan cover with nylon guard in the motor assembly arrangement.
Figure 7c illustrates the fan cover with steel mesh guard in the motor assembly arrangement.
Figure 7d illustrates the inner view of the fan cover in the motor assembly arrangement.
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concept of the term appropriately to describe its own invention in the best way. The present invention should be construed as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, it should be understood that equivalents and modifications are possible.
DETAILED DESCRIPTION OF INVENTION WITH REFERENCE TO ACCOMPANYING DRAWINGS
The present invention as embodied by “Integrated motor assembly with removable fan and airflow diverter" succinctly fulfils the above-mentioned need(s) in the art. The present invention has objective(s) arising as a result of the above-mentioned need(s), said objective(s) being enumerated below. In as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation(s)/ modification(s) applied to the structural alternative(s)/functional alternative(s) within its scope and purview. The present invention may be embodied in other specific form(s) without departing from the spirit or essential attributes thereof.
Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.
The present invention, with reference to figures 1 - 6, discloses an integrated motor assembly characterized in that is a removable fan 1 which is powered externally and is mounted on the shroud 2. The said shroud 2 acts as a mechanical mounting arrangement of the fan. Fan operating condition is controlled by motor based on the motor winding and casing temperature.
As seen in fig. 1, external powered fan 1 is mounted on the fan shroud 2 which is mounted with help of three studs/ screw inserts 13 in the motor NDE (non-drive end) bracket 4. Air flow from the fan 1 is diverted through a diverter 3 in one embodiment. Housing 5 is mounted on the NDE bracket 4. The air flow from the fan is focussed with help of diverter 3 and fan shroud 2. A sealing arrangement i.e O ring 6 (a rubber seal in shape of a torus) is provided on the NDE bracket 4 and the wire 8 sealing is ensured with a cable gland 9. The above sealing arrangement helps in realising IP67 (Ingress protection) sealing requirement. A steel guard 14 and screw insert are an integral part of the fan shroud 2 . The arrangement further comprises of ECU heat sink 12 that acts as an air diverter and supports metal clad power board 11. A Controller board 10 is mounted on the NDE bracket.
In One embodiment of the present invention, the airflow diverter 3 diverts the airflow from the fan. The said diverter 3 is an individual component affixed to non-drive end bracket 4 and it helps to focus air flow towards the housing fin 5 of the motor.
Another embodiment of the present invention is illustrated in PMSM (permanent magnet synchronous machine), wherein the rotor position is a very important factor in motor operation. In a typical arrangement, the position sensor is mounted on the NDE side of the bracket and sensing magnet placed on the NDE side of the shaft. Wherein with help of position sensing magnet and encoder IC (Integrated circuit) the rotor position is derived. The above information is used to run PMSM. Further, signal routing of PMSM is carried out, wherein the rotor position signal is obtained from the signal wire 8 for motor control, and at the same time IP67 protection also has to be ensured. The proposed arrangement addresses the same in a specific manner. This arrangement also acts as air diverter and also effectively implements sealing arrangement.
Another embodiment of the present invention comprises of the sealing arrangement wherein a rotor position sensor printed circuit board (PCB) 7 is fixed inside the diverter 3 and the cable gland 9 is used to ensure the sealing, which in turn helps to realise IP67 with help of O-ring 6. Further, the said sealing arrangement is used to fetch the rotor position sensor signal wire from the PCB 7 through non-drive end (NDE) bracket 4. The said rotor position sensor signal wire 8 is attached with cable gland 9. This approach helps in reducing the complexity of the sealing arrangement as there is no modification or objection in the air flow path of the air diverter.
Yet another embodiment is electronic control unit (ECU) which is integrated to the motor. The controller board 10 is placed in NDE bracket and the power board 11 is placed in the ECU heat sink 12. Fan 1 mounted on the shroud, cools the ECU first and then the motor. The said heat sink also acts as air flow diverter and diverts the air to flow into the housing heat sink 12. The said shroud 2 also helps to focus the air into the housing with fins 5. Specific shape and size and arrangement of ECU heat sink 12 and housing fins 5 are determined based on the computational fluid dynamics (a process to study the airflow and cooling factor).
In another embodiment the cooling fan 1 is mounted in the fan shroud 2. This shroud 2 provides sufficient mechanical support to the fan 1 and acts as a guide for air flow. Fig 7a is an ideal arrangement where there is no guard in front of the fan 1. In this arrangement safety and protection of the fan 1 are the main concern though there is no air resistance for the air flow as there is no cover in front of the fan 1. In conventional arrangement, the same material of the fan guard i.e nylon material with sufficient thickness and width is used. This arrangement ensures the safety and protection of the fan 1, however the efficiency of air flow is reduced because of the nylon fan cover. There are some possible measures taken by reducing the bridge thickness (the gap between the slots in the nylon guard 15) to reduce the air resistance. But there is some minimum limit beyond which the thickness/size of the material of the cover cannot be reduced. To overcome this limitation, a steel guard 14 is used as a separate member placed in front of the fan. This solution provides safety and protection as well as it acts as least resistance for the air flow.
However, the main concern of this arrangement is number of sundry parts used such as fan, steel guard and four screws and nuts which needs additional care and mechanism. In the arrangement in the present invention, a steel guard 14 with screw inserts 13 are moulded with the fan cover/ shroud 2 with help of insert moulding concept wherein it involves molding the specific parts around other parts. This method of integration helps in realising, safety and protection, least air flow resistance and reduces number of sundry parts.
Experimental results:
Below are some experimental data pertaining to performance of external powered fan comprising of air diverter with the sealing arrangement.
Experimental results show that, for getting an efficient air delivery of 7.5m/s with the given fan shroud 2 and a nylon guard 15, it takes an input power of 12.5W. For obtaining the same air delivery with fan shroud 2 with steel guard 14 it consumes 8W only. The resultant of the proposed idea brings down the fan input power by 40% for same air delivery which is very efficient in electric traction where the reduction in energy consumption of electrical load is required. This system along with the air diverter 3 facilities better airflow in the housing fin along with steel guard 14, higher air flow is realised for the same electrical input power as compared to the nylon guard 15.
A fan guard is generally used to efficiently obtain the air delivery from the fan, thus preventing any external disturbance. The air flow data without fan guard, with nylon 15 and steel guard 14 are shown below. Air flow is measured at the front side of the air flow direction as per the arrangement in fig 7d. It is measured at 10mm distance from the fan and 80% of the fan blade diameter. It is observed that air flow without any guard is 11.5m/s, with nylon cover it is 7.5m/s and with steel guard is 10.5m/s. Also, noise test is done in standard noise testing room (anechoic chamber). It is noted that low noise is measured without any guard, and with steel guard it is 79dB and with nylon it is 81dB. It is observed that noise with nylon guard is more than steel guard.
Arrangement Airflow, m/s Noise dB
Without any guard 11.5 77
With nylon guard 15 7.5 81
With steel guard 14 10.5 79

Advantages of the present invention:
1. Cost effective, light weight, external powered fan helps to cool the motor or ECU effectively. Since the fan is powered by external source, it is possible to realise variable speed operations of the fan depending on motor parameters.
2. Ability to reduce the temperature rise due to the external powered fan in the motor which helps to increase the motor power with given frame size. This is not effective in the existing shaft mounted fan arrangement motor.
3. As the speed of the fan is controlled independently, effective motor cooling is done even at low speed and high torque condition, but the air flow cannot be controlled or modified in the existing shaft mounted fan.
4. Reduces the air drag loss, because fan can be turned on as and when required based on the specimen motor winding temperature or casing temperature (operating condition).
5. External powered fan enables the elimination of oil seal arrangement in the present sealing arrangement, that ensures IP67 protection in existing shaft mounted fans.
6. Feasibility of reducing the shaft length is possible in external powered fan when compared to existing shaft mounted fan arrangement.
7. Typically, ECU produces lesser heat than the motor. Hence in the proposed arrangement the fan cools the low temperature ECU first and then motor housing is cooled next.
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the scope of the invention may be made by a person skilled in the art.