Claims:WE CLAIM
1) An integrated two part knob (11), comprising of the inner knob component (12) and the upper knob cover (61), independently made in injection moulding of plastic material, wherein by assembling and integrating said two parts (12) and (61)together preferably throughirreversible mutually locking arrangement such as press-fit arrangementsthe integrated knob (11) is formed; wherein said integrated two part knob(11) is characterized in accepting and firmly accommodating the shaft of the electromechanical switches, fan regulators dimmers etc. into the socket of inner knob component (12)preferably throughmutually locking arrangement such as press-fit arrangements.
2) An integrated two part knob (11), as claimed in claim 1 wherein in one of the most preferred embodiment, Inner knob component (12), on its inner portion, comprises all such structural features which are responsible for engaging said knob assembly (11) onto the shaft (23) of the electromechanical switch/ fan-regulator/dimmer etc., preferably throughmutually locking arrangement such as press-fit arrangements.
3) An integrated two part knob (11), as claimed in claim 1 wherein,in one of the most preferred embodiment, the upper surface of said knob component (12) and the inner surface of the knob cover (61) are created with such mutually corresponding structural arrangements so that said knob component (12) accommodate and locks the upper knob cover (61) above itself, by mutually locking arrangement such as press-fit arrangements.
4) An integrated two part knob (11), as claimed in claim 1 wherein,in one of the most preferred embodiment, the inner knob component (12) includes an injection moulded plastic tubular body (13) with a peripheral wall with tapered surface at (19) for gripping purposes, with a central hub (21) having a shaft receiving socket (23) and having its opening extended out of the end of the said tubular body (13) opposite to the end wall (27) wherein annular outwardly opening groove (29) is formed in the annular end wall (27) and upstanding collar (31) is formed at the inner periphery of the said annular end wall (27).
5) An integrated two part knob (11), as claimed in claim 1 wherein,in one of the most preferred embodiment,an annular passage (35) around the hub (21)into the tubular body (13)of the inner knob component (12) is defined by the collar (31) of the said annular end wall (27) and the central hub (21)therein; and an undercut (37) is formed in the said annular end wall (27); andribs (33) are formed to connect the hub (21), peripheral wall (15) and the annular end wall (27) of the said tubular body (13).
6) An integrated two part knob (11), as claimed in claim 1 wherein,in one of the most preferred embodiment, the knob cover (61) is injection moulded of a suitable plastic and it comprises a head (63) whereina short tubular base (67) extends from the under surface (65) of the head (63) of the said knob cover (61) and also whereindiscrete elongated fingers (69), ending in a tip (71), are formed on the said tubular base (67) and arranged in a circle, wherein said elongated fingers (69) of said knob cover (61) is characterized in having inner walls (73) and locking lugs (75) on the exterior of each finger intermediate the tubular base (67) and the finger tips (71).
7) An integrated two part knob (11), as claimed in claim 1 whereinthe two parts of the said knob are assembled into one integrated part by an irreversible fitment process which does not require use of any third part like screws, dowels, pins or any other connecting member.
8) An integrated two part knob (11), as claimed in claim 1 whereintwo different partstwo parts, (12) and (61), of the knob assembly (11) are integrally manufactured, but stillthey are characterized in their optionally selected, preferably different sets of mechanical and structural properties, namely colour, texture, touch and feel, plastic material, strength and abrasion, and wherein the shape and dimension of the upper knob cover (61) is optionally selected for the outer part even though the geometry and shape of the shaft for switches / regulators / dimmers etc are standardized across the varieties of appliances and equipment.
9) An integrated two part knob (11), as claimed in claim 1 whereinthe two parts (12) and (61) are individually produced from metal or plastic or rubber or any other natural or synthetic material having necessary properties as required by the application.
, Description:FIELD OF INVENTION:
The present invention relates to an integrated two part knob to be used with electromechanical switches, fan regulators, dimmers and various appliances and equipments; wherein particularly said integrated two part knob relates to an inner knob which is fitted to the shaft of the said switches/regulators/dimmers, and, an outer part which is fitted to the inner part by irreversible mutually locking arrangement such that the two parts become an integrated single knob after their assembly.

Background of the invention and prior art:
The knob of a switch, fan regulator or dimmer is usually a plastic or metal component, and, is fitted to the switch/dimmer/regulator shaft by press fitting or by screw on the cylindrical surface or directly on the switch axis.

Since such switches/ regulators/dimmers are to be installed in a limited space in appliances or equipment, hence, these switches/regulators/dimmers are preferably designed with smallest possible dimensions and thereby their operating shafts are generally very small in size, and, almost impossible to be operated by hand (finger and thumb). Hence, various types of knobs are used practically to connect to such shafts and thereby allowing users to operate the switches/regulators/dimmers. The knob diameters are generally larger and ergonomically suiting the hand movement (thumb and finger) to easily rotate the shaft and thereby operate the switches/ regulators/dimmers.

Most commonly used shaft for the switches/regulators/dimmers has ‘D’ shaped end, wherein the knob is fixed on said ‘D’ shaped region of said shaft by press fitting. In another embodiment of switches/regulators/dimmers, knob component is placed above the shaft and is fixed with the said shaft using a screw at its cylindrical side wall.

In yet another embodiment of switches/regulators/dimmers, knob inner body is fixed to the shaft end by screw and an upper body of the knob is then fixed suitably to the said inner body of the knob, preferably using mechanical means.

Problems associated with the prior arts:
Conventional knobs used for the movement of electromechanical switches used for control of various functions in the conventional air coolers are associated with at least one drawback, as indicated below:
i. If the single part knob is soft and with easy grip provisions, the same will not be rigid and strong enough to drive the shaft of an electro-mechanical switch;
ii. If the single part knob is rigid and strong to drive the shaft of an electro-mechanical switch, then it will not offer a good, soft and easy grip for manual operation.
iii. The entire single part knob is in single colour. Unless masked and painted, which would be expensive, the knob can’t be produced in dual colours. Hence, such dual colour aesthetics is not feasible unless making an expensive design.
iv. Injection moulded knob will have a constraint of the construction of the tool for injection moulding, and, hence, this restricts the possible geometry configurations for single part knob.
v. In case of knobs screwed to the shaft using a screw at its cylindrical side wall, such screw may come out from the shaft due to continuous abrasion and damage of threading inside shaft which holds said screw. Sometimes the shaft breaks at the section where screw is pointing and penetrating it. Also, such screw is easily visible and hence is not aesthetically pleasing.
vi. In case of knobs with inner part of knob screwed to the shaft along its axis, there are multiple problems: (a) Shaft becomes weak due to hole and threads for the axial screw, (b) there is always a possibility of over-tightening of such screws leading to breakage of shaft and / or screw and / or the knob, (c) in case the upper part of the knob comes out from its location (due to poor assembly or poor dimensional consistency or any other reasons), then, the screw of the inner part is directly visible, which is not aesthetically pleasing.
vii. In case of knobs with screws in either type (screws on shaft axis or screws on cylindrical side wall), there are always chances of screws getting rusted and further disturbing the aesthetic appeal and also loosing strength. At the same time chances of its threads getting loose over a period of time is always there, and thereby knob coming out from its position, leading to non-functioning of the switches/regulators/dimmers. Other problems of knobs using screw are: (a) It adds a part in form of screw, (b) Hence, the cost goes up, (c) Even the assembly time goes up, (d) Replacement of damaged knob requires a use of screw driver and hence not easily done by household person.

The present invention is intended to eliminate / substantially alleviates the disadvantages in the conventional knobs, as mentioned hereinabove.

OBJECTS OF THE INVENTION:
The object of the present invention is to provide an integral screw-less two partsknobfor movement of electromechanical switches/fan regulators/dimmers etc.,to be used invarious electrical appliances and equipment; wherein said two parts of the knob assembly are made in injection moulding and will get engaged with each other by irreversible mutually locking arrangement such as press-fit arrangements between them and wherein further said knob assembly is provisioned to be assembled firmly on the shaft of said electromechanical switches/fan regulators/dimmers etc., preferably through irreversible mutually locking arrangement such as press-fit arrangements between the socket of said knob assembly and the shaft.

Another object of the present invention is to provide such knob assembly which can be easily manufactured using known and easily accessible technologies, particularly the injection moulding of plastic material(s).

Another object of the present invention is to permit the knob to have two different characteristics, soft on finger / thumb touch, but rigidly connected to the switches.

Further another object of the present invention is also to permit dual colour aesthetics for the knob without the need for expensive masking and painting processes.

SUMMARY OF THE INVENTION:
The present invention relates to an improved knob for operating electromechanical switches, fan regulators, dimmers etc. and are made integrally out of two parts; wherein said two parts of the knob assembly are provisioned to be joined together without any screw and also the said integrated knob is provisioned for mounting to the shaft of the switch/dimmer/regulator without using any screw.
With this arrangement, the knobs with much improved aesthetics and enhanced structural strengthof knob as well as its components are achievedand also said knob assembly is easy to operate (better ergonomics).

The knob of the present invention is designed to be used for operating the electromechanical switches, fan regulators, dimmers etc. used in any kind of appliances or equipment.

There are two main knob components, the inner knob component and the upper knob cover, which are independently made in injection moulding, wherein each of these two components consists of suitable irreversible mutually locking arrangement such as press-fit arrangements so that they mutually get assembled together and at the same time the socket of inner knob component has press-fit provisions towards accepting and firmly accommodating the shaft of the electromechanical switches, fan regulators dimmers etc., made to be used for electrical appliances and equipments.

DETAILED DESCRIPTION OF THE INVENTION:
The invention will now be described and illustrated with reference to the accompanying schematic drawings wherein the same numerals are used to denote the same parts. However, it is made clear that the description and the drawings only illustrate the invention and in no way limit the same.

Figure 1: It represents a top plan schematic view of the assembled multi-piece knob of theinvention;
Figure 2: It represents a bottom schematic view of the assembled multi-piece knob as shown in Figure 1;
Figure 3: It represents schematic cross sectional view taken along line 2—2 of figure1;
Figure 4: It represents schematic enlarged top plan view of the top locking cap;
Figure 5:It represents schematic cross-sectional view taken through line 3—3 of figure 4;
Figure 6:It represents schematic enlarged top plan view of the knob;
Figure 7: It represents schematic cross-sectional view taken through line 4—4 of figure 6;
Figure 8 is an isometric view of the disassembled multi-piece knob of this invention;
Figure 9 is an isometric view of the assembled multi-piece knob of this invention.

Figures 1 to 9 of the drawings show a first embodiment of the invention in a multi-piece knob. There are two main knob components, the inner knob component (12) and the upper knob cover (61), which are independently made in injection moulding and by assembling and integrating them together to form the integrated knob (11).
Inner knob component (12), on its inner portion, comprises all such structural features which are responsible for engaging the knob assembly (11) onto the shaft(23) of the electromechanical switch/ fan-regulator/dimmer etc., preferably through irreversible mutually locking arrangement such as press-fit arrangements. The upper surface of said knob component (12)and the inner surface of the knob cover (61) are created with such mutually corresponding structural arrangements that said knob component (12) accommodate and locks the upper knob cover (61) above itself, mainly through irreversible mutually locking arrangement such as press-fit arrangements therein. Said knob assembly (11) is provided with such structural features so that none of the knob components, (12) and (61) require any screw or mechanical/chemical means to get assembled together and at the same time said inner knob component (12) does not require any screw or mechanical/chemical means for engaging with the shaft of the electromechanical switches.

The inner knob component (12)includes a plastic tubular body (13) which is conventionally injection moulded of a suitable plastic. The body is formed with a peripheral wall. The surface is tapered at (19) for gripping purposes. The tubular body (13) is also formed with a central hub (21) having a shaft receiving socket (23)and having its opening extended out of the end of the tubular body 13 opposite to the end wall (27). The socket (23)is shown herein as conventional D-shaped socket (figure 2) but other socket cross-sections may be provided. The socket has an entrance (25) for receiving the end of a shaft. An annular end wall (27) is formed integrally with the tubular body (13). An annular outwardly opening groove (29) is formed in the annular end wall (27). An upstanding collar (31) is formed at the inner periphery of the annular end wall (27). The collar (31) of the annular end wall (27) and the central hub (21) define an annular passage (35) into the tubular body (13)around the hub (21). An undercut (37) is formed in the annular end wall (27). Ribs (33) are formed to connect the hub (21), peripheral wall (15) and the annular end wall (27) of the tubular body (13). Whereas, for clarity of illustration, the peripheral wall (15), central hub (21), annular end wall (27) and ribs (33) are shown as moulded integrally as part of the plastic tubular body (13), it should be understood that all or some of these parts may be formed separately and assembled to form the tubular body (13).

The knob cover (61) is shown in its assembled position in figures 3 and 9 of the drawings and unassembled in figures 4, 5 and 8 of the drawings. As shown in figure 5,the knob cover (61) which is injection moulded of a suitable plastic in conventional manner. Theknob cover(61) includes a head (63) which is somewhat concave on its outer surface and somewhat convex on it'sunder surface(65). A short tubular base (67) extends from the under surface(65) of the head (63) of the knob cover(61). Discrete elongated fingers (69) are formed on the tubular base and arranged in a circle. Each of the elongated fingers (69) ends in a tip (71). While is it preferred that the press-fitting locking lugs be located intermediate the base and that tip of each finger, the lugs may be located at the tip of each finger. The elongated fingers have inner walls (73) and locking lugs (75) on the exterior of each finger intermediate the tubular base (67) and the finger tips (71).
The inner knob component (12) and, knob cover 61 may be individually produced prior to assembly. Upon assembly, the top knob cover 61 is placed over the annular end wall (27) of the inner knob body (12).

Towards creating the aesthetics, colouring effects and touch & feel features (such as soft and non-slippery effects), particularly on the upper surface of the top knob cover (61) which comes in contact with fingers and thumb of the operator, the plastic material of the said upper knob cover (61) can be optionally selected in such a manner that said plastic material supports effective injection moulding operation towards creating all structural features in the knob cover (61), as described hereinabove. Said plastic material of the upper knob cover (61) may or may not be same as the plastic material of the inner knob component (12). By a variation in the plastic material and their colour combinations for the said upper knob cover 61 and the said inner knob component (12), the complete assembly of the knob (11) can be produced as many optional embodiments, as described hereinabove.

A brief consideration of the above embodiment will indicate that the invention is simple.

In addition to the above mentioned most preferred embodiments, it is to be understood that various other modifications and alterations with regard to the types of the materials used, their method of joining together, and the attachments, and the shapes / dimensions / orientations of the components as described, the absence of certain optional components as described, and/or function may be made to the disclosed embodiments by one skilled in the art without departing from the invention as defined by the claims. Accordingly, the above disclosure is not to be considered as limiting and the appended claims are to be interpreted as encompassing the entire spirit and scope of the invention.

ADVANTAGES OF THE INVENTION:
This invention offers the following advantages:
• Knob has two different functional requirements. First of all, it fits on the shaft of the electromechanical switch / fan regulator / dimmer etc. and drives the same, and, hence, has to be strong/rigid enough to rotate the electro-mechanical switch. Secondly, it is manually operated (usually by a thumb and a finger), and, hence, should be soft and non-hurting and should have firm grip. If knob is constructed from two different parts, the inner part can be made from a rigid and strong material to drive the electromechanical switch, whereas the outer surface part can be soft and non-hurting and providing better hand grip.
• Two part knob offer an advantage of a possibility to offer different colours and textures of two parts and thereby a superior aesthetic appeal.
• Integral two part knob of the present invention is produced using an assembly technique of irreversible fit of second part on the first part. Hence, even though they give features and benefits of two parts, the knob still functions as one integral knob.
• Since the two parts are different, their mould construction could be different; hence, as a result, it is possible to obtain variety of combination of geometry.
• Since the integral knob does not use any screw, neither to connect the two parts together, nor to connect the inner part with switch shaft, hence, the problems associated with screws (as described in the problems associated with prior art) are all eliminated.