FORM2
THE PATENTS ACT 1970
39 OF 1970
&
THE PATENT RULES 2003
COMPLETESPECIFICATION
(SEE SECTIONS 10 & RULE 13)
1. TITLEOF THE INVENTION
“SODIUM FILLED THERMOMETRIC VALVE AND AN OPTIMIZATION
METHOD THEREOF”
2. APPLICANTS (S)
(a) Name: Durovalves India Pvt. Ltd.
(b) Nationality: Indian
(c) Address: F-57/58, MIDC Waluj,
Aurangabad - 431136,
Maharashtra,
India
3. PREAMBLETOTHEDESCRIPTION
COMPLETESPECIFICATION
The following specification particularly describes the invention and the manner in which it is to be performed

FIELD OF THE INVENTION
The present disclosure relates to a sodium filled thermometric valve, and more particularly relates to determining at least one optimized parameter for a sodium filled thermometric valve by determining actual temperature reached on exhaust valve in an engine during operation of the sodium filled thermometric valve.
BACKGROUND
In an engine valve of an automobile, in order to respond to an increase in performance or to reduce the weight of engine valve train components, a hollow portion is provided in an elongated stem portion of the valve and its bore is partially filled with metallic sodium. The purpose of filling metallic sodium in the bore is to achieve fast dissipation of heat by transfer of heat from thermally highest loaded valve region of an internal combustion engine to a further away region. This is possible due to extraordinary superior heat conductivity of the metallic sodium. Use of this methodology reduces overall valve temperature by 80 to 120oC. This category of valve is used for high performance engines. However, an appropriate design of such a valve requires information as accurately as possible on how much temperature is attained on the engine valve sin an internal combustion engine in running condition.
Conventional methods for predicting engine valve temperature include software based Finite Element Analysis (FEA) method and direct thermocouple temperature measurement method. However, predicting engine valve temperature

using FEA and direct thermocouple measurement methods have their set of limitations/disadvantages. For instance, in case of analyzing the temperature using a design software, i.e., thermal – stress analysis by FEA method, accurate input parameters are required to be provided into the system. More specifically, the exhaust valve temperature is simulated in design software by considering engine boundary conditions. The temperature to which the hollow sodium filled valve shall be exposed as obtained using simulation is verified through testing the particular engine with thermometric valves. In some aspects, actual data is not available and assumed data needs to be fed in the software and this becomes a limiting factor for accurate prediction of the temperature. Thus, the FEA method is a method of “predicting” temperature and not actually “measuring” temperature in the engine. Further, the method of analyzing temperature with the help of thermocouple temperature sensor valves is a direct and most preferred method. However, this method of manufacturing these valves involves one of the most sophisticated advanced technology and is an extremely costly method. Further, the thermocouple method involves drilling the valve stem up to the valve radium portion. Since the diameter of engine valves is few mm in size, the drilling of valve stem up to the valve radius portion to accommodate the thermocouple of certain diameter is a challenging task considering strength of the valves at such loading condition. Hence, it is not possible to produce these valves with conventional manufacturing facilities. In addition to that, assembling of these categories of valves in the engine head is also a challenging task, as many rotating parts are already there in engine head gallery along with lubricant.

Consequently designing, manufacturing and testing of these conventional valves is not easy. Accordingly, there is a requirement of a method/process which shall be cost effective, simpler and gives determination of engine temperature which should be very close to what will be obtained by thermocouple temperature sensor valves, but far more accurate than the prediction provided by the FEA method. More specifically, to facilitate designing of an optimum hollow sodium filled valve, a process/method was needed since a very long time, since hollow sodium filled valves first came in use, for determination of exact temperature of the engine that shall be attained in continuous use.
SUMMARY
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the disclosure. This summary is neither intended to identify key or essential inventive concepts of the disclosure and nor is it intended for determining the scope of the disclosure.
In an embodiment of the present disclosure, a method for determining at least one optimized parameter for a sodium filled thermometric valve is disclosed. The method comprises exposing the sodium filled thermometric valve to an increasing temperature range by operating an engine with the sodium filled thermometric valve for a predefined time duration. Further, the method comprises determining a change in hardness of a material of the sodium filled thermometric valve after operating the engine with the sodium filled thermometric valve for the predefined time duration.

Furthermore, the method comprises determining an actual temperature of the engine operated sodium filled thermometric valve based on correlation of the change in hardness of material with a predefined relationship between temperature and hardness of the material. In addition, the method comprises determining the at least one optimized parameter for the sodium filled thermometric valve based on the determined actual temperature.
In an embodiment of the present disclosure, a sodium filled thermometric valve is disclosed. The sodium filled thermometric valve comprises a valve head made of a first material; a hollow portion comprising a first end coupled to the valve head, wherein the hollow portion is adapted to be filled with metallic sodium; and a stem portion coupled to a second end of the hollow portion, wherein the stem portion is made of the first material. Further, a hardness of the first material of the sodium filled thermometric valve is adapted to be modified when the sodium filled thermometric valve is exposed to an increasing temperature within an engine.
To further clarify advantages and features of the present disclosure, a more particular description of the disclosure will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope. The disclosure will be described and explained with additional specificity and detail with the accompanying drawings.

BRIEF DESCIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Figures 1A and 1B illustrate a cut-sectional view of a sodium filled thermometric valve, in accordance with an embodiment of the present disclosure;
Figure 2 illustrates a process flow depicting a method 300 for determining at least one optimized parameter for a sodium filled thermometric valve, in accordance with an embodiment of the present disclosure;
Figures 3A and 3B illustrate an exemplary set of coordinates/points on an outer periphery of the sodium filled thermometric valve, according to an exemplary embodiment of the present disclosure;
Figures 4A and 4B illustrate an exemplary set of temperature values on the periphery and in the interiors of the sodium filled thermometric valve, according to an exemplary embodiment of the present disclosure; and
Figure 5 illustrates a process flow diagram for manufacturing of sodium filled thermometric valves, in accordance with an embodiment of the present disclosure.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present disclosure.

Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
DETAILED DESCRIPTION OF DRAWINGS
For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the disclosure relates. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
The term “some” as used herein is defined as “none, or one, or more than one, or all.” Accordingly, the terms “none,” “one,” “more than one,” “more than one, but not all” or “all” would all fall under the definition of “some.” The term “some

embodiments” may refer to no embodiments or to one embodiment or to several embodiments or to all embodiments. Accordingly, the term “some embodiments” is defined as meaning “no embodiment, or one embodiment, or more than one embodiment, or all embodiments.”
The terminology and structure employed herein is for describing, teaching and illuminating some embodiments and their specific features and elements and does not limit, restrict or reduce the spirit and scope of the claims or their equivalents.
More specifically, any terms used herein such as but not limited to “includes,” “comprises,” “has,” “consists,” and grammatical variants thereof do NOT specify an exact limitation or restriction and certainly do NOT exclude the possible addition of one or more features or elements, unless otherwise stated, and furthermore must NOT be taken to exclude the possible removal of one or more of the listed features and elements, unless otherwise stated with the limiting language “MUST comprise” or “NEEDS TO include.”
Whether or not a certain feature or element was limited to being used only once, either way it may still be referred to as “one or more features” or “one or more elements” or “at least one feature” or “at least one element.” Furthermore, the use of the terms “one or more” or “at least one” feature or element do NOT preclude there being none of that feature or element, unless otherwise specified by limiting language such as “there NEEDS to be one or more . . .” or “one or more element is REQUIRED.”

Unless otherwise defined, all terms, and especially any technical and/or scientific terms, used herein may be taken to have the same meaning as commonly understood by one having an ordinary skill in the art.
Reference is made herein to some “embodiments.” It should be understood that an embodiment is an example of a possible implementation of any features and/or elements presented in the attached claims. Some embodiments have been described for the purpose of illuminating one or more of the potential ways in which the specific features and/or elements of the attached claims fulfil the requirements of uniqueness, utility and non-obviousness.
Use of the phrases and/or terms such as but not limited to “a first embodiment,” “a further embodiment,” “an alternate embodiment,” “one embodiment,” “an embodiment,” “multiple embodiments,” “some embodiments,” “other embodiments,” “further embodiment”, “furthermore embodiment”, “additional embodiment” or variants thereof do NOT necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and/or elements described in connection with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and/or elements may be described herein in the context of only a single embodiment, or alternatively in the context of more than one embodiment, or further alternatively in the context of all embodiments, the features and/or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and/or elements

described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.
Any particular and all details set forth herein are used in the context of some embodiments and therefore should NOT be necessarily taken as limiting factors to the attached claims. The attached claims and their legal equivalents can be realized in the context of embodiments other than the ones used as illustrative examples in the description below.
Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.
The present disclosure discloses a method for temperature determination required for designing a hollow sodium filled valve to ensure high performance of the valve as well as the turbo charged engine during early design stage. This disclosure also provides a method for optimizing design parameters of a hollow sodium filled valve with respect to various dimensions of hollow portion of the valve and quantity of sodium to be filled in it for optimum performance for heat dissipation/transmission from hot region of the engine to other parts for engine longevity, safety and more efficient performance.
Figures 1A and 1B illustrate a cut-sectional view of a sodium filled thermometric valve 100, in accordance with an embodiment of the present disclosure. Referring to Fig. 1A, the sodium filled thermometric valve 100 may comprise a valve head 102, a hollow portion 104, and a valve stem 108. Further, the hollow portion

104 may be filled with metallic sodium, as discussed throughout this disclosure. The valve head 102 and the valve stem 108 may be made up of a same material. Further, the hollow portion 104 may include a first end 110 and a second end 112. The first end 110 may be coupled to the valve head 102, while the second end 112 may be coupled to the valve’s stem portion 108.
Various embodiments of the present disclosure relate to determining one or more optimized parameters for designing of the sodium filled thermometric valve 100. The optimized parameters for the sodium filled thermometric valve 100 may include, but not limited to, a length of the hollow portion 104, a diameter of the hollow portion 104, and a volume of the hollow portion 104 which comprises the metallic sodium.
Specifically, in one embodiment of the present disclosure, the sodium filled thermometric valve 100 may be configured to be exposed to an increasing temperature range in an engine for a predefined duration of time, such as, but not limited to, 2 hours. The engine may include an internal combustion engine such as, but not limited to, a 4W 1200cc engine. Further, the engine may be operated for the predefined duration of time with full throttle condition. Subsequent to the predefined duration of time, a change in hardness of the material of the sodium filled thermometric valve 100 may be determined. In particular, a hardness of the material of the valve 100 before (e.g., default hardness of material) and after (i.e., a new hardness value) the exposure of the sodium filled thermometric valve 100 for the predefined duration of time may be determined. The hardness may be determined at

one or more points/coordinates on the periphery of the sodium filled thermometric valve 100.
Once the hardness of the sodium filled thermometric valve 100 is determined, an actual temperature of the engine operated sodium filled thermometric valve 100 may be determined. The actual temperature may be determined based on a predefined correlation of the change in hardness of material with a predefined relationship between temperature and hardness of the material. Further, based on the determined actual temperature, at least one optimized parameter may be determined. Furthermore, the at least one optimized parameter (e.g., diameter, length, and/or volume) of the sodium filled thermometric valve 100 may also depend on the type of engine and its capacity.
The sodium filled thermometric valve 100 may be made up of a material which responds to an operating condition of the engine. In an exemplary embodiment, the material may include, but not limited to, X50CrSi82, SUH-11, or X45CrSi93 grade material of Martensitic valve steel may be used to manufacture these valves, which is sensitive enough to respond to the temperature attained by the engine during testing. Additionally, the X45CrSi93 grade material of Martensitic valve steel shows drop in hardness proportionate with increasing tempering temperature for a given duration of soak time/time to which the sodium filled thermometric valve 100 is exposed in the test at high temperature. Thus, in the same embodiment of using X45CrSi93 grade material for the sodium filled thermometric valve 100, once the valve 100 is exposed to determine change in hardness attained by

the valve 100 during testing conditions, a temperature vs hardness plot of X45CrSi93 material may be used to determine the actual temperature physically attained by the engine during test conditions.
Referring to Fig. 1B, the sodium filled thermometric valve 100 is depicted. All the components depicted in Fig. 1A for the sodium filled thermometric valve 100 are not marked again in Fig. 1B. As depicted, the sodium filled thermometric valve 100 may be coupled to a valve guide 114, wherein the metallic sodium in the valve 100 transmits heat from the valve head 102 towards the stem portion 108 and the valve guide 114 present in the engine.
Figure 2 illustrates a process flow depicting a method 200 for determining at least one optimized parameter for a sodium filled thermometric valve, in accordance with an embodiment of the present disclosure.
At step 202, the method 200 comprises exposing the sodium filled thermometric valve to an increasing temperature range by operating an engine with the sodium filled thermometric valve for a predefined time duration. In one embodiment of the present disclosure, the sodium filled thermometric valve may include a valve head, a hollow portion comprising a first end coupled to the valve head, and a stem portion coupled to a second end of the hollow portion. The hollow portion is adapted to be filled with metallic sodium.

At step 204, the method 200 comprises determining a change in hardness of a material of the sodium filled thermometric valve after operating the engine with the sodium filled thermometric valve for the predefined time duration
At step 206, the method 200 comprises determining an actual temperature of the engine operated sodium filled thermometric valve based on a correlation of the change in hardness of material with a predefined relationship between temperature and hardness of the material.
At step 208, the method 200 comprises determining the at least one optimized parameter for the sodium filled thermometric valve based on the determined actual temperature. In one embodiment of the present disclosure, the at least one optimized parameter may include a diameter, a length of the hollow portion, and a volume of the metallic sodium to be filled within the hollow portion of the valve.
At step 210, the method 200 comprises manufacturing at least one other sodium filled thermometric valve for the engine based on the at least one optimized parameter.
Further, in an embodiment of the present disclosure, determining the at least one optimized parameter comprises determining an optimum amount of metallic sodium to be filled in a hollow portion of the sodium filled thermometric valve based on the determined actual temperature, and wherein the metallic sodium transmits heat from the valve head towards the stem portion and a valve guide present in the engine.

Figures 3A, 3B, and 3C illustrate an exemplary set of coordinates/points on an outer periphery of the sodium filled thermometric valve, according to an exemplary embodiment of the present disclosure.
As illustrated, for mapping the temperature, hardness is measured on a tested sodium filled thermometric valve cross section, as per the exemplary layout depicted in Figs. 3A, 3B, and 3C. In one embodiment, the hardness may be measured on the tested sodium filled thermometric valve cross section at 0.1mm from the outer periphery of the valve, as depicted in Fig. 3B.
The co-ordinates of the specific points are taken at specific intervals depending on a number of points required for measurement. In one embodiment, the hardness of the valve may be measured via standard techniques known in the domain of present disclosure, such as, but not limited to, Vickers micro-hardness measurement method. For the sake of brevity and since these techniques are well-known, these are not discussed here in detail.
Referring to Fig. 3B, an exploded view of an exemplary section 302 of the sodium filled thermometric valve part is provided. The section 302 is along the longitudinal axis of the valve and metallurgical specimen mounting and polishing is done as per ASTM E3. The section 302 may be used for hardness measurement. Once the specimen moulding and polishing is completed, the hardness measurement may be performed via, for example, Vickers micro-hardness tester. The various points for hardness measurement, such as section 302, may be located at 0.1mm from the

surface of the valve. The co-ordinates for various points of measurement are illustrated in Fig. 3A.
The hardness data may be collated for various coordinates/points as depicted in Figs. 3A and 3C and filled in below format provided in Table 1, to convert the measured hardness into a corresponding temperature. The coordinates/points may be categorized into multiple areas of the valve such as face (points O, A, B, C, D, E, F), seat (points 1, 2, and 3), radius (4, 5, and 6), and stem (7-18). Further, the coordinates/points may be associated with a relative distance among the points, from a starting point “O” on the face of the valve. The valve ID may indicate the specific valve corresponding to location of valve in engine, e.g., cylinder number.

Area Point Name Valve ID Valve ID

Distance (mm) HV Temp
Face O 0

A 2

B 4

C 6

D 8

E 10

F 12
Seat,
Radius &
Stem-1 1 0.5

2 1

3 2

4 4

5 6

6 8

7 10

8 12

9 14

10 16

11 18

12 20

13 22

14 24

15 26

16 28

17 30

18 32
Table 1 Once the hardness data is collated, the hardness (HV) may be converted to temperature based on below exemplary formula provided in Equation (1):
(1) wherein,
y = Temperature in °C ; and
x = Hardness in HV
Figures 4A and 4B illustrate an exemplary set of temperature values on the outer periphery and on the interior periphery of the sodium filled thermometric valve, respectively, according to an exemplary embodiment of the present disclosure. In an embodiment, once all the required temperature data is available based on the exemplary formula illustrated in Figs. 3A and 3B, the temperature values may be illustrated in a visual format (e.g., display interface of a computer) as given in Figs. 4A and 4B.

An exemplary set of temperature measurement along with corresponding hardness is provided below in Table 2:

Area Point Name Valve ID Valve No.1

Distance (mm) HV Temp
Face 1 O 0 344 699

A 2 362 673

B 4 366 667

C 6 407 615

D 8 431 587

E 10 426 593

F 12 456 561
Face 2 A 2 332 718

B 4 345 698

C 6 353 686

D 8 403 619

E 10 432 586

F 12 466 551
Seat, Radius & Stem-1 1 0.5 456 561

2 1 452 565

3 2 431 587

4 4 350 690

5 6 306 762

6 8 325 729

7 10 312 751

8 12 300 773

9 14 291 790

10 16 289 794

11 18 283 806

12 20 281 810

13 22 326 728

14 24 358 679

15 26 376 654

16 28 584 452

17 30 654 406

18 32 666 399
Figure 5 illustrates a process flow diagram 500 for manufacturing of sodium filled thermometric valves, in accordance with an embodiment of the present disclosure. In summary, following steps are followed for making a hollow sodium filled thermometric valve. The valve head material is hot forged as per the required drawing specification. Further, the valve head is hardened up to its hardening temperature (1050±10oC, 20-25 minutes soaking time) followed by oil quenching. Similar hardening process is carried out for the valve stems. As per the conventional manufacturing process, the valve head is drilled up to required length followed by sodium filling and friction welding process. According to one embodiment of the present disclosure, this dimension of drilling depends on engine design parameters such as, but not limited to, guide length and valve position. The friction weld length is kept such that drilled cavity stays in valve guide during valve operation to facilitate effective heat transfer. In one present exemplary embodiment, it may be approximately 57 – 61% of total length of valve. The friction welding is the process where heat affected zone is generated near welding zone, and it shall not affect the location of measurement on the valve surface. As valve head and valve stem are in hardened condition, it is necessary to relieve the stresses that might have developed during quenching of the material from its hardening temperature zone. Stress relief process is carried out after friction welding operation in a box furnace. Stress relief is

done at 250±10oC for 45 minutes followed by air cooling. The remaining valve manufacturing process is same as that of conventional method to manufacture the thermometric valves. In an exemplary embodiment, the valve is uniformly hardened, and hardness is maintained in the range of 57±1 HRC.
Further, in one exemplary embodiment, the length of the valve head may be in a range of 57mm to 63mm, and wherein a shaft diameter of the valve head is in a range of 5.1525mm to 5.1675mm. Furthermore, a length of the hollow portion (i.e., bore length) may be 54mm, and wherein a diameter of the hollow portion is in a range of 2.90mm to 3.10mm. Also, the length of the stem portion may be in a range of 38.3mm to 44.3mm. As it may be understood by a person skilled in the art, these dimensions are only illustrative and not limiting dimensions of valves as claimed in this disclosure. The dimensions of hollow sodium filled thermometric valves for different engines shall be different. Even for same engine, for different targets of drop in temperature, the depth of the hollow bore and the quantity of sodium filled will be different; and all such variations and equivalents are included within the scope of the disclosure disclosed herein.
An illustrative set of processes followed for manufacturing of valves as per an embodiment of the present disclosure are discussed herein below. Since most of these processes are conventionally known for manufacturing of thermometric valves, these are not discussed here in detail.
Head: Steps in making Head.
Bar shearing: Required length of head material is cut-off from long bars.

Bar grinding: Grinding process is done to get required diameter of the bar
and to achieve required straightness & roundness of bar.
Deburr: This operation is done to remove burrs at the edge of the bars.
Upset Forging: The bar is hot forged to get required profile of valve head
portion along with required process output parameters.
Straightening: Machine straightening is done to get required straightness &
radius run out of the valve head portion.
Stress relieve: This operation is done to relieve stress that might have
developed during machine straightening operation. It is done at 700±10⁰C, 60
minutes followed by air cooling.
Hardening: Heating of valve head portion in box furnace at 1050±10⁰C
temperature, 20-25 minutes soaking time followed by oil quenching.
Shot blast: It is done to remove scaling from valve head portion after oil
quenching.
Tip End grinding: It is done to maintain required length & end run out
before friction welding operation.
Deep hole drilling: Bore is created using gun drilling operation in valve head
portion as per design specification.
Washing and Drying: Bore is washed & dried to ensure absence of any
external particles inside the drilled portion of valve head.

Auto Sodium filling: In this operation, metallic sodium is filled inside the bore, and valve head portion is ready for friction welding process with valve stem portion. Stem: Steps in making Stem.
Bar shearing: Required length of stem material is cut-off from long bars. Hardening: Heating of the valve stems in box furnace at 1050±10⁰C temperature, 20-25 minutes soaking time followed by oil quenching. Shot blast: It is done to remove scaling from valve stem portion after oil quenching.
End touch: This operation is done to remove burr from end of valve stem bars and valve stem is ready for friction welding operation with valve head portion.
Friction welding & deflash: valve head and valve stem is friction welded to get required length and diameter at weld joint.
Stress relieve: It is carried out after friction welding operation in a box furnace. Stress relief is done at 250±10⁰C for 45 minutes followed by air cooling.
Auto Bend test: It is done to check required weld strength of the friction welded valve.
Rough Center less: It is grinding process and used to get required diameter, straightness, roundness of the part.

Pre-machining final inspection: It is done to check some of the critical
parameters at semi-finish stage to proceed further.
Rough Center less II: It is grinding process and used to get required
diameter, straightness, roundness of the part. The material is removed in
consequence processes to get required surface finish of the finish part.
Turn Head Dia (THD) Facing, Chamfer back of head: It is turning
process, where valve head dia, seat height, face run out, face finish all other
parameters are maintained as per designed process.
Profile turning Neck & radius: It is also turning process, where valve
radius, radius angle, neck angle neck dia is maintained as per designed
process.
Wet End I: It is grinding process, where valve end is ground to get required
overall length.
Intermediate center less grinding + Grind reduce stem (GRS I): It is done
to reduce stem diameter, grinding length, blending radius, GRS dia, GRS
length.etc.
Groove grinding & chamfer: It is grinding process to generate groove and
chamfer on valve stem.
Intermediate center less grinding + Grind reduce stem (GRS II): It is
done to reduce stem diameter, grinding length, blending radius, GRS dia,
GRS length.etc.

Finish End: It is valve tip end grinding process, and required to get valve tip
end run out, surface roughness and overall length as per final drawing
requirement.
Grind seat: It is vale seat grinding process, where parameters related to valve
seat like seat angle, seat roundness, seat roughness, seat height, seat run out is
maintained as per final drawing specification.
Cleaning: Valve is cleaned, and all the dirt and dust are removed in this
operation.
Final Inspection: Visual inspection and major dimensional inspection done
to ensure product parameters as per product drawing specifications.
The metallic hollow sodium filled valve used conventionally in Internal Combustion engines is made by drilling the valve head portion up to required length with gun drilling machine. After filling of 50 to 60% metallic sodium into the bore, the open end is friction welded with valve stem material. In conventional hollow sodium filled valve, the valve head material is mainly austenitic steel and valve stem is of martensitic steel material. In general, the exhaust valve head material is austenitic steel due to its stability at higher operating temperature and facilitate the sodium filled valves to last longer during use.
On the contrary, however, thermometric valves are meant not for long use but for only one time use of measuring temperature that reaches in operating an engine in a cycle of maximum 2 hours based from the degree of hardness reached

during the test period from which the temperature reached during the test can be found out from the validated equation of temperature vs hardness for this grade of steel. Hence, for thermometric valves, Martensitic steel material X45CrSi93 is used for the head as well as stem material of thermometric valves. Thus, the Martensitic steel material can help in determining exhaust valve temperature. Thus, the thermometric valve made from Martensitic Steel material X45CrSi93 was being used in a full throttle test for 2 hours for verifying the estimate of temperature at which the hollow sodium filled conventional valve will likely be exposed to in an internal combustion engine; where the estimate was done by thermal-stress analysis by FEA mode or with the help of thermocouple temperature sensor valves.
However, in various embodiments of the present disclosure, instead of using a conventionally known thermometric valve for validating the temperature estimated by thermal-stress analysis by FEA mode or with the help of thermocouple temperature sensor valves, the hollow sodium filled thermometric valve was made. As discussed throughout this disclosure, this hollow sodium filled thermometric valve is used in the full throttle test for 2 hours and the temperature reached is determined from the validated equation of temperature vs hardness of Martensitic Steel material X45CrSi93 grade. The conventional mechanisms do not help in optimizing the sodium cavity parameters based on temperature analysis as carried out in present case.

In another embodiment of the present disclosure, an exposure method of the sodium filled thermometric valve is provided as discussed above, wherein with the help of thermometric hollow sodium filled valves, an actual exhaust valve temperature is determined in an actual engine. This method provides a highly accurate and actual information on the exhaust valve temperature for a certain internal combustion engine and for a certain design of a hollow sodium filled thermometric valve fitted in it, which shall be applicable to all conventional valves made on the same design for same engine, wherein valve head material is mainly austenitic steel and valve stem is of Martensitic steel material. Although not needed, optionally the determined temperature by the method of this disclosure can be corroborated with simulated results for the same engine boundaries condition. Examples of engine boundary conditions may include, but not limited to, peak combustion pressure, exhaust gas temperature, spring loads on intake and exhaust side, valve lift, maximum load on valve tip, valve seating velocity, engine configuration i.e., naturally aspirated or turbocharged, seat insert and valve guide dimensions along with assembly details.
Thus, advantageously, with the hollow sodium filled thermometric valve discussed herein, the exhaust valve temperature can be very accurately determined in a high performance and turbo-charged engine over conventional methods. In addition to that, an effectiveness of sodium filling can also be confirmed for particular engine condition compared to solid stem valve to decide best suitable design for the engine. Further, it is also possible to optimize the

design parameters of the hollow sodium filled valve by making varying designs of hollow sodium filled thermometric valves and selecting the best performing design. Further, it is an additional advantage of this disclosure that the sodium filled thermometric valves can be manufactured with the conventional sodium filling technology. No additional facility is required to manufacture these valves, as also illustrated in Fig. 5.
In addition, the present disclosure combines the use of thermometric valves for temperature determination and also design optimization (e.g., length, diameter, and volume of hollow portion) for hollow sodium filled valves into a single product – i.e., hollow sodium filled thermometric valves. Hence, this new technology helps in actually determining the sodium filled exhaust valve temperature for high-performance and turbo engines with high exhaust gas temperature. It could also help in assessing effectiveness of sodium filling for particular engine boundary condition.
While specific language has been used to describe the present subject matter, any limitations arising on account thereto, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein. The drawings and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements

may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment.

We Claim:
1. A method (200) for determining at least one optimized parameter for a sodium
filled thermometric valve (100), the method (200) comprising:
exposing (202) the sodium filled thermometric valve (100) to an increasing temperature range by operating an engine with the sodium filled thermometric valve (100) for a predefined time duration;
determining (204) a change in hardness of a material of the sodium filled thermometric valve (100) after operating the engine with the sodium filled thermometric valve (100) for the predefined time duration;
determining (206) an actual temperature of the engine operated sodium filled thermometric valve (100) based on a correlation of the change in hardness of material with a predefined relationship between temperature and hardness of the material; and
determining (208) the at least one optimized parameter for the sodium filled thermometric valve (100) based on the determined actual temperature.
2. The method (200) as claimed in claim 1, wherein the sodium filled
thermometric valve (100) comprises:
a valve head (102),
a hollow portion (104) comprising a first end coupled to the valve head (102), wherein the hollow portion (104) is adapted to be filled with metallic sodium, and
a stem portion (108) coupled to a second end of the hollow portion (104).

3. The method (200) as claimed in claim 2, wherein determining (208) the at least one optimized parameter comprises determining at least one of a length and diameter of the hollow portion based on the determined actual temperature.
4. The method (200) as claimed in claim 2, wherein determining (208) the at least one optimized parameter comprises determining an optimum amount of metallic sodium to be filled in a hollow portion of the sodium filled thermometric valve (100) based on the determined actual temperature, and wherein the metallic sodium transmits heat from the valve head (102) towards the stem portion (108) and a valve guide (114) present in the engine.
5. The method (200) as claimed in claim 1, wherein determining (208) the at least one optimized parameter for the sodium filled thermometric valve (100) comprises:
determining one or more temperature values along a periphery of the sodium filled thermometric valve (100) after operating the engine with the sodium filled thermometric valve (100) for the predefined time duration; and
determining (208) the at least one optimized parameter of the sodium filled thermometric valve (100) based on the determined one or more temperature values.
6. The method (200) as claimed in claim 1, comprising:
manufacturing (210) at least one other sodium filled thermometric valve (100) for the engine based on the at least one optimized parameter.
7. A sodium filled thermometric valve (100) comprising:
a valve head (102) made of a first material;

a hollow portion (104) comprising a first end coupled to the valve head (102), wherein the hollow portion (104) is adapted to be filled with metallic sodium; and
a stem portion (108) coupled to a second end of the hollow portion (104), wherein the stem portion (108) is made of the first material,
wherein a hardness of the first material of the sodium filled thermometric valve (100) is adapted to be modified when the sodium filled thermometric valve (100) is exposed to an increasing temperature within an engine.
8. The sodium filled thermometric valve (100) as claimed in claim 7, wherein the first material comprises X45CrSi93 grade material of Martensitic Valve steel.
9. The sodium filled thermometric valve (100) as claimed in claim 7, wherein the hardness of the first material, after exposure of the sodium filled thermometric valve (100) to the increasing temperature for a predefined duration, corresponds to an actual temperature of the engine valve.