Claims:CLAIMS
We Claim :
1. A BLDC Hub motor assembly, comprising:
a shaft with a hexagonal profile in the middle of the shaft by eliminating the key slot with key;
a stator housing hub comprising a hexagonal slot in the middle to facilitate mounting of the shaft by eliminating the hexagonal steel sleeve in aluminium housing hub, said stator housing hub with five spokes in curve shaped designed to churn airflow;
multiple segments of laminates configured to interlock with one another and also to lock with the Stator housing hub, wherein the interlocked segments along with stator housing hub provides a tight and sturdy fit;
dual set of hall-effect sensors placed on both sides of the stator housing opposite / perpendicularly to each other, and configured to detect the change in magnetic flux which allows detection of misalignment of the shaft or bearing worn out /alignment, wherein a single hall-effect sensor is configured to detect the change in magnetic flux by reading the change in flux density at any given time to a pre-set magnetic flux intensity value and also to detect the damage of the magnets.
2. The BLDC Hub motor assembly as claimed in claim 1, wherein , out of the dual set of hall-effect sensors, even if one hall-effect sensor fails, then the other will be used without any need for a change in architecture or any physical effort.
3. The BLDC Hub motor assembly as claimed in claim 1, wherein thermal sensors are placed in the winding of the motor to monitor the temperature of the motor.
4. The BLDC Hub motor assembly as claimed in claim 1, wherein a Controller area network (CAN) is integrated into the motor to control the inter-changeability of the motors with the OEM assembled vehicle, said CAN CAN specify motor will work only in the specified vehicle, and wherein CAN is configured to identify any failure in the Hall-effect sensor or can identify if any hall sensor is not working without even removing the motor from the vehicle, and additionally to also detect shaft wear-out, bearing wear-out, magnet damage, and misalignment and wherein the CAN is connected to a temperature sensor to detect temperature rise and take preventive action.
5. The BLDC Hub motor assembly as claimed in claim 1, wherein motor cover plates are provided with fins on both internal and external side of motors and groove is provided to mount rubber cap which acts as labyrinth seal to prevent dust and water seepage.
Dated this the 05th February 2021

Senthil Kumar B
Agent for the applicant
IN/PA-1549
, Description:
FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
Complete Specification
(See section 10 and rule 13)

1.Title of the Invention :
Two-Wheeler Electrical Vehicle – BLDC Hub Motor Assembly

2. Applicants
Name Nationality Address
NDS ECO MOTORS PVT LTD

Indian

SREE BALAJI NILAYA, 9TH MAIN, CHOWDESHWARI LAYOUT, MARATHAHALLI, BANGALORE 560037, KARNATAKA

3. Preamble to the Description :
The following specification particularly describes the invention and the manner in which it is to be performed.

4. DESCRIPTION
Field of the Invention
The present invention is related to the field of Direct current motor and more particularly to an automobile brushless direct current motor.
Object of the invention
The object of this invention is to provide a permanent magnet brushless direct current (PMBLDC) motor with simple reasonable structure and having functions of saving energy and environmental protection.
PMBLDC motor: - A rotor of the motor is a hub of a wheel and the inner diameter of the hub is permanent magnets. A stator (armature winding) is connected to the shaft of the wheel.
Simple in structure: - As the rotor and stator are integrated within the hub of the wheel, thereof the structure is simple, compact, and reasonable.
Saving energy: - the speed regulation for the motor and direct drive for the wheel by the motor can be realized via electric control, so the weight can be reduced and no transmission loss thus that saves the power consumption.
Background of the Invention
A brushless DC electric motor (BLDC motor or BL motor), also known as an electronically commutated motor (ECM or EC motor) and synchronous DC motors, are synchronous motors powered by direct current (DC) electricity via an inverter or switching power supply which produces electricity in the form of alternating current (AC) to drive each phase of the motor via a closed-loop controller.
Hub motors are typically brushless motors (brushless direct current motors or BLDCs), which replace the commutator and brushes with separate coils and an electronic circuit. In a brushed DC motor, the rotor spins 180-degrees when an electric current is run to the armature.In brushless DC motors, the permanent magnets are on the rotor, and the electromagnets are on the stator. A computer then charges the electromagnets in the stator to rotate the rotor a full 360-degrees.
Like any other electric motor, a BLDC motor also has a stator and a rotor. Here we will consider Stator and Rotor each separately from a construction point of view. A stator consists of a shaft and a rotor hub with permanent magnets arranged to form between two to eight pole pairs that alternate between north and south poles.
Detailed Description of the invention
The Motor consists of two main parts {Fig 1}
1. Stator {fig 1.1}
2. Rotor {fig 1.2}

STATOR: -
The stator is a stationary device that consists of the following parts,
1. Shaft (Fig 2.1)
2. Stator housing hub (Fig 2.2)
3. Laminates (Fig 2.3)
4. Winding’s (Fig 2.4)
5. Hall effect sensor (Fig 2.5)
6. Temperature Sensor (Fig 2.6)
7. CAN-Bus (Fig 2.7)
8. Motor wiring harness
ROTOR: -
The rotor is a rotary device that consists of the following parts,
1. Motor rim with rotor ring (Fig 8.1)
2. Magnets (Fig 8.2)
3. Motor cover plate( Fig9)

STATOR
Shaft: -
In the BLDC Hub motor, the shaft is the stationary part that provides the fitment of the motor in the vehicle. It holds the stator hub firmly so it does not vary the position of the stator during high-speed running and vibration on road. It also acts as a load distributor from the motor to the vehicle swing arm. We have designed a Hexagonal shaft refer to Fig 3.1 for our application. In our design Hexagonal projection is given at the center of the shaft so the contact of the shaft and the stator hub is obsolete so that no slip between the shaft and center hub.
Performance: -
Usually in normal circular shafts key slot is provided for positioning and better stability but in the hexagonal shaft,a key is not required as it gives better fitment and slip-proof.
The induction hardening process is done at the bearing sitting area refer to Fig 3.2a & 3.2b to reduce the shaft wear out and to withstand more load on the motor.
Safety: -
EN19* grade material used to increase shaft breaking point which is more than 350Nm, so that the shaft life is increased by 50%.
EN19: - EN19 is high-quality alloy steel with tensile strength. It is a high-quality medium carbon, with a combination of good ductility and shock resistance. EN19 is suitable for applications with very high loading such as engine gearboxes. Popular in the automotive sector it is possible to machine the material extremely accurately, in recent years EN19 has become an established material in the Oil & Gas sector. The material lends itself well to any application where strength is a primary consideration. EN19 is a prime choice because of its high strength. EN19 Steel is one steel grade in BS 970-1955 standard, which is the specification for wrought steels. EN-19 Steel comes under the class of low alloy steel. EN-19 material has high fatigue strength, abrasion and impact resistance, toughness, and torsional strength. EN 19 material can be heat treated in several ways to give it a combination of properties. Oil Quenched & Tempered Hardness is 28-34 HRc. EN 19 Annealing delivery hardness is less than 250HB and has a high tensile strength of 850-1000 Mpa.
Maintenance: -
We have designed the Hexagonal shaft in such a way it's easy to replace than that of a key slot shaft because the key may get damaged or misplaced while removing or by fitting.

Details of the shaft and hub assembly with hexagon mounting with Zoomed view is provided in the annexed drawings.
Stator housing hub: -
Stator housing is made of diecast Aluminium refer to Fig 4. Stator housing hub connects both the shaft with the hexagonal slot refer to Fig 4.2 and armature firmly. First, the shaft is inserted to housing that is in hexagon slot, then the Armature laminates are staked and inserted in slots provided in the housing refer Fig 4.3, the slots in housing for laminations give firm fitment and it doesn’t allow it move for any vibration and the housing has threaded holes to mount the staked lamination for a firm fit as shown in Fig 4.4.

We have designed the stator with five spokes in curve design as shown in Fig 4.1 because of which the churning air will hit and flow directly to windings and magnet, heat dissipation happens fast and has high strength. In stator housing, the diecast aluminium spokes are provided for more strength when compared to sheet metal. The aluminium is corrosion resistant and is a very good conductor of heat.
Laminates: -
Laminates are made from electrical sheets (silicon steel sheet). Thin Laminates are made 84 turns then stacked and riveted rather than using a single metal sheet because of which the eddy current losses reduce. The overall length of the staked laminates increased to produce higher torque.
With the conventional design of the single-piece lamination for hub motor, the material wastage is as high as 84%. In one exemplary embodiment of the invention, to reduce the wastage of overall material used for the lamination, the lamination is split into 6 pieces as shown in Fig 5.1. The split pieces are provided with a proper interlocking mechanism to restrict the relative motion of laminates as shown in Fig 5.2.
Also, a groove in the hub is given to place the laminates for proper insertion into the assembly (refer Fig 5.3) and locked using bolts. This ensures the tight fit of the laminations on the hub. The laminate sheet is coated with non-corrosive spray. We have designed the laminates in such a way that if the motor power is increased in the future, we can go with the same laminates without any modifications.
Windings: -
Winding is made through the copper with a 120 degree phase angle. The winding sequence is made to achieve high speed (refer to Fig 2.4). The copper strands are coated with “Class H” insulation that can withstand high temperatures up to 180 Degree C and winded very tightly because one strand shouldn’t rub with the other. Winding enclosed around a coated flexible iron magnetic core to shape magnetic poles while strengthened with the current.
After the winding process, the Armature is coated with resin to avoid rub between winding and laminates. The resin used is “Class H” insulation that can withstand high temperatures up to 180 Degree C. The winding is made as a star connection for more efficiency and simple is construction. Insulation paper is used in between the laminates and winding. A thin piece of wood is used to separate two slots in laminates for better insulation and firm fit.
Hall-Effect Sensor: -
The hall-effect sensor is operated by the magnetic field from the permanent magnet or an electromagnet, which response to north and south poles to switch ON & OFF. The built-in regulator provides enhanced stability of operation from 4.5 Vdc to 24 Vdc supply voltage range, and the internal circuitry is designed to prevent sensor damage in case the supply voltage polarity is accidentally reversed. We use two different modules hall-effect sensor that Is one on LHs & other is RHs as shown in Fig 6.1a & 6.1b. We use a bipolar hall-effect sensor that has high magnetic gauss sensitivity.
Two modules of the hall-effect sensor to read the magnetic flux getting generated at different locations in the stator. The amount of magnetic flux difference between hall-effect sensor modules 1 and 2 is set to a pre-determined level in the microcontroller unit. If the magnetic flux difference exceeds the limiting value during the operation of the vehicle over time, it indicates the bearing is getting worn out or a misalignment issue is there as shown in Fig 7.1. The magnetic flux changes due to a change in the air gap between magnet and hall-effect sensor due to the bearing wear out or misalignment in the shaft. This changed air gap will affect the magnetic flux intensity. Any change in magnetic flux above or below a critical limit will be measured without dismantling the motor. This will allow the user to immediately take necessary action to get it corrected without causing any failure of the system.
The hall-effect sensor modules are coated with conformal coating to protect from ESD (Electrostatic discharge). It also acts as waterproof.
Temperature Sensor: -
The temperature sensor is used to detect temperature rise in the motor winding, as in BLDC motor winding is the place where a lot of heat is generated so the temperature sensor is mounted in winding (refer to Fig 2.6). As the temperature increases that communicates with the microcontroller unit to take preventive measures that’s like sending minimum power to the motor until it cools.
NTC (negative temperature coefficient) with high resistance is used so that the module will not go to overvoltage.
CAN: -
We have developed CAN (controller area network) that is integrated with the motor (refer Fig to 2.7) to make the motor intelligent and high safety. We designed CAN sink with the vehicle's unique identification number so that the specified motor will work only with the specified vehicle controller. The reason for this is the motor identification number will be registered in RTO and the motor number should not be changed without noticing the RTO. With CAN inbuilt we can control the inter-changeability of the motor with the OEM assembled vehicle.
The CAN architecture is designed in such a way that it is connected to both the hall-effect sensor modules. The CAN will detect if any one hall-effect sensor fails and it automatically tunes in such a way that the motor will work with only one hall-effect sensor, as we have two modules of hall-effect sensor one fails the other one will work. CAN also detect if there’s any shaft or bearing wear out and any misalignments in the motor by the change of the magnetic field which is sensed by the hall-effect sensor as shown in Fig 7.1.
The CAN will also be connected to the motor temperature sensor, by which the CAN will take preventive measures to make the motor cool down when the motor temperature rises beyond the set limit that is by pumping very little power into the motor.
Wiring Harness: -
We use a single core wiring harness, in which three wires are of phase wire to the motor and CAN input and output wires. The CAN wire will be sleeve with metal shielded wire for Electromagnetic susceptibility because the phase wire's noise level shouldn’t affect motor feedback wires. And entire wiring harness will be metal shielded for Electromagnetic interference protection. All the wires are Teflon sleeved for better stability and to withstand higher temperatures.

ROTOR

Motor rim with rotor ring: -
The motor rim is a directly connected motor ring that is for no transmission losses. 12-inch wheel rim is used for better stability.
The rotor ring is magnetic metal as the magnets will be attached to this ring which will be facing the stator. The magnetic metal is used because it has very good properties of magnetic attraction. Both the side will be mounted to the rotor ring with fasteners.

Magnet: -
Magnets are placed in the rotor ring by facing the stator. 35H magnets are used for better torque and high speed. We’re going with Nickel-Chromium-Nickel (NiCrNi) plating for water-resistant. Magnets are placed, unlike wise alternating poles. The magnet working temperature is from -20 to 120 degree C.

Motor cover plates: -
Motor cover plates are made by pressure-cast aluminium alloy to make them lighter and stronger. There are two different covers used to cover the stator and rotor that is LHS (Left Hand Side) & RHS (Right Hand Side) with brake drum inbuilt as shown in fig 9.1 &9.2.

The plates are designed with fins on both sides i.e., Internal fins and External fins. Internal fins churn the air inside the motor that hits the stator and as the stator has curve shaped spokes, the air will directly hit windings and magnets and makes it cool faster and the inside motor becomes cool (refer to Fig 9.3 & 9.4).
External fins transfer all the heat from the inside to the outside air surroundings when the motor is running, because of fins heat dissipation happens sooner (refer to Fig 9.1 & 9.2).
The Motors cover plates IP68 protection we are providing a rubber cap with 1 or more labyrinth seal on top as shown in fig 10.2, the double lip seal (refer to fig 10.1) on the shaft as shown in fig and also the gasket is used on both sides of the cover plates with silica gel. We even use waterproof bearings (2RS Bearings) on both the covers which makes the motor dust and waterproof that is IP68.
In a preferred embodiment this invention is a BLDC Hub motor assembly. The main features include a shaft with a hexagonal profile in the middle of the shaft by eliminating the key slot with key. A stator housing hub comprising a hexagonal slot in the middle is used to facilitate mounting of the shaft by eliminating the hexagonal steel sleeve in aluminium housing hub. The stator housing hub is built with five spokes in curve shaped designed to churn airflow. Multiple segments of laminates are configured to interlock with one another and also to lock with the Stator housing hub, wherein the interlocked segments along with stator housing hub provides a tight and sturdy fit. A dual set of hall-effect sensors are placed on either sides of the stator housing opposite / perpendicularly to each other, and configured to detect the change in magnetic flux which allows detection of misalignment of the shaft or bearing worn out /alignment. The configuration is made in such a manner that wherein a single hall-effect sensor is enough to detect the change in magnetic flux by reading the change in flux density at any given time to a pre-set magnetic flux intensity value and also to detect the damage to the magnets.
Thermal sensors are placed in the winding of the motor to monitor the temperature of the motor. A Controller area network (CAN) is integrated into the motor to control the inter-changeability of the motors with the OEM assembled vehicle. This CAN specifies the particular motor which will work only in the specified vehicle. The CAN is configured to identify any failure in the Hall-effect sensor or can identify if any hall sensor is not working without even removing the motor from the vehicle, and additionally to also detect shaft wear-out, bearing wear-out, magnet damage, and misalignment. The CAN is connected to a temperature sensor to detect temperature rise and take preventive action. The BLDC Hub motor assembly also has motor cover plates which are provided with fins on both internal and external side of motors and a groove is provided to mount rubber cap which acts as labyrinth seal to prevent dust and water seepage.

Description of Drawings
Fig 1: Details of motor assembly segregated into two parts – Stator Fig 1.1 and Rotor Fig 1.2
Fig 2: Ilustration of constructional details of the motor stator with its child parts
Fig 3: Illustration of Constructional details of the motor shaft with the hexagonal profile in the center of the shaft.
Fig 4: Illustration of constructional details of the motor Stator housing hub with the hexagonal profile in the center and curve-shaped spokes with the Zoomed view
Fig 5: Illustration of constructional details of motor Stator laminations with segmented piece zoomed view and Interlocking mechanism
Fig 6 : Illustration of architecture of the dual Hall-effect sensor placed in Laminations
Fig 7 : Illustrated construction of stator misalignment with respect to magnet
Fig 8 : Illustration of constructional details of the motor Rotor split view
Fig 9 : Illustration of constructional details of motor cover plates with Fins on both sides and rubber cap with a labyrinth seal
Fig 10 : Illustration of constructional details of labyrinth seal assembled in motor with Zoomed view

Senthil Kumar B
(Agent for the applicant)
IN/PA-1549