Description:FORM – 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See section 10, Rule 13]

A SHAFT AND BOSS ASSEMBLY

BLUE STAR LIMITED A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS BLUE STAR LIMITED, BLUE STAR INNOVATION CENTRE, NEXT TO VIHANG’S INN HOTEL, KAPURBAVDI, GHODBUNDER ROAD, THANE WEST – 400 607, MAHARASHTRA, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
A SHAFT AND BOSS ASSEMBLY
FIELD OF THE INVENTION
The present disclosure relates to a shaft and boss assembly.

BACKGROUND OF THE INVENTION
Generally, in a shaft and boss assembly, a shaft with a D-cut portion is attached to a boss with a D-shape receiving hole for the D-cut shaft portion. The shaft and boss assemblies used in an air conditioning unit have the boss of a plastic fan attached to the shaft of a motor. The fan is used for forced air movement and heat transfer in the air conditioning unit. Generally, sensor less motors are used in air conditioning units. The sensor less motors require synchronous control at start-up between the motor shaft and plastic fan. Sensor less motors need to detect the angle of a rotor of the motor by detecting a motor current. In the air conditioning unit with sensor less motors, it is necessary to rotate the motor once to detect the motor current. This operation is called an open-loop control.
As illustrated in FIGS. 1a, 1b and 1c, the shaft (102) in the shaft and boss (104) assembly (100), rotates from side to side in the open-loop control operation of the air conditioning unit. The shaft (102) and boss (104) have a minor tolerance variance. Due to this minor tolerance variance, a very small gap (106) is formed between the shaft (102) and the boss (104). When the shaft (102) rotates from side to side, the D-cut shaft (102) hits the D-shaped receiving hole of the boss (104), thereby causing vibration and noise. A rotational speed difference also gets created between the shaft (102) and boss (104). Circumferential vibration is caused due to the rotational speed difference. The collisions (108) between the shaft (102) and the boss (104) occur till the motor starts running in the desired direction.
The vibrations caused due to the collisions (108) between the shaft (102) and the boss (104) lead to loosening of a nut used to lock the fan and motor together. The vibrations also lead to damage to the fan in the long run. The vibration and noise also lead to abnormal noises at start-up time of the motor.
The alternative to the sensor less motors are motors with magnetic field spot sensors. The motors with magnetic field spot sensors are very costly. The alternative to plastic fans are fans with a metallic boss. The fans with the metallic boss are costly as well.
Therefore, there is a need for a cost-effective alternative to the present shaft boss assembly which can eliminate the vibrations, noises, and the relative motion between the shaft and the boss, while making use of the sensor less motor and the plastic fan.

SUMMARY OF THE INVENTION
In one aspect of the present invention, a shaft and boss assembly is provided. The shaft and boss assembly includes a shaft having a chamfered D-cut portion and an extended threaded portion at a free end. The shaft and boss assembly also includes a boss having a D-shaped receiving hole corresponding to the D-cut portion of the shaft, for receiving the D-cut portion of the shaft. The shaft and boss assembly further includes a nut removably fastened along with a washer on the threaded portion of the shaft. Further, the shaft and boss assembly includes a C-ring disposed below the washer between the chamfered surface of the shaft and the boss in such a manner that an axial force through the nut pushes the C-ring in downwards direction thereby allowing a rigid connection and eliminating a relative motion between the shaft and the boss.
According to the present invention, the C-ring has an arc shape.
According to the present invention, the shaft and boss assembly is used in an air conditioner unit.

BRIEF DESCRIPTION OF THE DRAWING
FIGS. 1a, 1b and 1c illustrate a perspective view of a conventional shaft and boss assembly during an open-loop control;
FIG. 2 illustrates a perspective view of an outdoor unit of an air conditioning unit, according to the present disclosure;
FIG. 3 illustrates a perspective view of a shaft and boss assembly, according to the present disclosure;
FIG. 4 illustrates a perspective view of a fan, according to the present disclosure;
FIG. 5 illustrates an exploded view of the shaft boss assembly, according to the present disclosure;
FIG. 6a illustrates a sectional view of the shaft and boss assembly, according to the present disclosure;
FIG. 6b illustrates an enlarged sectional view of the shaft and boss assembly of FIG. 4a, according to the present disclosure; and
FIG. 7 illustrates a perspective view of the shaft and boss assembly along with a C-ring; according to the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION.
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawings.
Embodiments are provided to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth relating to specific components to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
References in the present disclosure to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in an embodiment” or “in an implementation” in various places in the specification are not necessarily all referring to the same embodiment or implementation.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises,” “comprising,” “consists,” “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated elements, modules, units and/or components, but do not forbid the presence or addition of one or more other elements, components, and/or groups thereof.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
FIG. 2 illustrates an outdoor unit (200) of an air conditioner unit (not shown). The outdoor unit (200) of the present embodiment includes a compressor (202), a condenser coil (204), a motor (206), and a fan (208). It should be noted that the outdoor unit can include other components without limiting the scope of what is disclosed. The outdoor unit (200) is connected to an indoor unit (not shown) of the air conditioner unit with the help of copper pipes (210). The connection between the outdoor unit (200) and indoor unit facilitates the flow of a refrigerant (not shown). The compressor (202) adds pressure to the refrigerant in order to increase the temperature of the refrigerant. The refrigerant flows through the condenser coils (204) after leaving the compressor (202). The fan (208) is used for forced air movement and heat transfer in the air conditioner unit. As the refrigerant flows through the condenser coils (204) the fan (208) blows air on the condenser coils (204) to cool down the condenser coils (204) and bring about a heat exchange. The temperature of the refrigerant reduces and the heat is released to the air outside. The refrigerant is pumped from the condenser coils (204) of the outdoor unit (200) to the indoor unit. The fan (208) that cools the condenser coils (204) is connected to the motor (206) with the help of a shaft and boss assembly (212). The shaft and boss assembly (212) of the present disclosure is used in an air conditioning unit.
FIG. 3 illustrates a perspective view of the shaft and boss assembly (212) according to the present disclosure. The shaft and boss assembly (212) includes a shaft (214). A free end (216) of the shaft (214) has a threaded portion (218). The threaded portion (218) of the disclosed embodiment has threads of M10 size. It should be noted that the threaded portion (218) of the shaft can be of any other specification without limiting the scope of what is disclosed. The shaft (214) also includes a D-cut portion (220) proximate the threaded portion (218). The D-cut portion (220) has a chamfered surface (222).
The shaft and boss assembly (212) also includes a boss (224) of the fan (208). The boss (224) of the disclosed embodiment is made of plastic. It should be noted that the boss (224) can be made of any other material without limiting the scope of what is disclosed.
As illustrated in FIG. 4 the boss (224) has a D-shaped receiving hole (226). The D-shaped receiving hole (226) corresponds to the D-cut portion (220) of the shaft (214). The D-shaped receiving hole (226) receives the D-cut portion (220) of the shaft (214). The D-cut portion (220) and the D-shaped receiving hole (226) enable the prevention of slippage as the shaft (214) turns.
The shaft and boss assembly (212) further includes a nut (228) with a washer (230) removably fastened on the threaded portion (218) of the shaft (214). The nut (228) of the disclosed embodiment has threads of size M10. It should be noted that nut (228) of any other thread size can be used without limiting the scope of what is disclosed. In the disclosed embodiment the nut (228) is a hexagonal nut. It should be noted any other nut (228) can be used without limiting the scope of what is disclosed.
The shaft and boss assembly (212) further includes a C-ring (232). The C-ring (232) of the present disclosure has an arc shape. More specifically the arc shape is an arc slightly smaller than a semi-circle. It should be noted that the arc of the c ring can be of any size without limiting the scope of what is disclosed.
As illustrated in FIG. 5, the C-ring (232) is disposed below the washer (230) and between the chamfered surface (222) of the shaft (214) and the boss (224).
As illustrated in FIGS. 6a and 6b, the C-ring (232) is disposed below the washer (230) in such a manner that an axial force through the nut (228) pushes the C-ring (232) in downwards direction thereby allowing a robust connection and eliminating a relative motion between the shaft (214) and the boss (224).
As illustrated in FIG. 7, when the nut (228) is fastened, a force is exerted on the C-ring (232) in a downward direction. The force acts upon the chamfered surface (222) and the boss (224). The force exerted on the chamfered surface (222) and the boss (224) by the C-ring (232) enables the elimination of slipping/relative motion between the shaft (214) and the boss (224). The force also holds the C-ring (232) in place between the chamfered surface (222) of the shaft (214) and the boss (224).
The C-ring (232) facilitates the elimination of collisions between the shaft (214) and boss (224) as disclosed in the prior art. The Force exerted by the C-ring (232) enables the elimination of the collisions by ensuring a firm fitment of the shaft (214) and the boss (224). The elimination of collisions between the shaft (214) and the boss (224) eliminates the vibrations in the air conditioning unit, during an open-loop control. The elimination of vibration eliminates abnormal noise at start up time. The elimination of vibration and noise reduces risk of damage to the fan (208).
The present disclosure eliminates slipping/relative motion between the shaft and the boss. The present invention eliminates vibrations and noise in the shaft and boss assembly. The present invention enables elimination of vibrational sound while using a low cost fan (fan without metal boss) and a brushless direct current (DC) motor (without magnetic field spot sensor).
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
Any discussion of devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

, Claims:
1. A shaft and boss assembly (212) comprising:
a shaft (214) having a chamfered D-cut portion (220) and an extended threaded portion (218) at a free end (216);
a boss (224) having a D-shaped receiving hole (226) corresponding to the D-cut portion (220) of the shaft (214) for receiving the D-cut portion (220) of the shaft (214);
a nut (228) removably fastened along with a washer (230) on the threaded portion (218) of the shaft (214); and
a C-ring (232) disposed below the washer (230) between the chamfered surface (222) of the shaft (214) and the boss (224) in such a manner that an axial force through the nut (228) pushes the C-ring (232) in downwards direction thereby allowing a rigid connection and eliminating a relative motion between the shaft (214) and the boss (224).
2. The shaft and boss assembly (212) as claimed in claim 1, wherein the C-ring (232) has an arc shape.
3. The shaft and boss assembly (212) as claimed in claim 1 or claim 2, wherein the shaft and boss assembly (212) is used in an air conditioner unit.