DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
A HYDRAULIC TORQUE CONVERTER WITH IMPROVED TORQUE ABSORPTION CAPACITY

Applicant:
BEML Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
BEML Soudha, 23/1, 4th Main,
Sampangirama Nagar, Bengaluru - 560 027,
Karnataka, India

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

CROSS REFERENCE TO RELATED APPLICATION AND PRIORITY
The present invention claims priority from Indian patent Provisional Application 202141021250 filed on 10th May, 2021.

TECHNICAL FIELD OF INVENTION
The present invention relates to a hydraulic torque converter with enhanced torque absorption capacity. More particularly, the present disclosure relates to a hydraulic torque converter with an impeller configured with an inverted impeller blade design for enhancing the torque absorption capacity.

BACKGROUND OF INVENTION
Conventionally, a hydraulic torque converter in an automotive equipment have been designed to transfer rotating power from prime mover (e.g., engine) to a load/ a transmission with the help of fluid. The hydraulic torque converter comprises an impeller, a turbine and a stator to ensure smooth circulation of fluid and efficient hydrodynamic torque transfer between impeller and turbine.
In a vehicle powertrain, any of a squash type hydraulic torque converter or a round type hydraulic torque converter is used. The sectional views of squash type hydraulic torque converter (201) and round type hydraulic torque converter (202) are shown in Figure 2 that illustrates the arrangement of turbine (210, 250), stator (230, 260) and impeller (220, 240) blades for squash and round type hydraulic torque converters.
An exemplary conventional impeller blade design is as shown in Figure 3A. The mean camber line (305) also referred as design path is the locus connecting the centres of the series of circles which are tangent to both surfaces of the twisting blade profile. The design path or the mean camber-line (305) is determined with the help of computational fluid dynamics with elimination of negative pressure from shell to core portion of impeller blade surface which is exactly equivalent to continuously varying double surface type of hydrofoil. In figure 3A, Q1 is an impeller entry angle measured from a zero-reference point on torque converter axis to the line (306) tangent to the mean camber-line (305) projected in the direction of flow from the entry point on the design path and Q2 is an impeller exit angle measured from a zero-reference point on torque converter axis to the line (307) tangent to the mean camber-line projected in the direction of flow from the exit point on the design path. In the exemplary conventional impeller blade design, the impeller entry angle (Q1) is maintained greater than 90 degrees (Obtuse Angle) and the impeller exit angle (Q2) is maintained lesser than 90 degrees (Acute Angle).
A conventional squash type hydraulic torque converter as shown in Figure 4A comprises an impeller (220), a turbine (210) and a stator (230). As illustrated in Figure 5A, in conventional impeller blade design (510), the impeller entry angle (Q1) is maintained always greater than 90 degrees (Obtuse Angle) and the impeller exit angle (Q2) is maintained always lesser than 90 degrees (Acute Angle).
A conventional round type hydraulic torque converter as shown in Figure 6A comprises an impeller (240), a turbine (250) and a stator (260). As illustrated in Figure 7A, in conventional impeller blade design (710), the impeller entry angle (Q1) and the impeller exit angle (Q2) are maintained always lesser than 90 degrees (Acute Angle).
However, it is observed that the hydraulic torque converter having conventional impeller blade designs as described above has a constraint of torque absorption capacity in-terms of torus envelope. There is a need of an improved impeller blade design for enhancing the torque absorption capacity and efficiency of the hydraulic torque converter without increasing the torus size.

OBJECTS OF THE INVENTION
The object of the invention is to provide a hydraulic torque converter with enhanced torque absorption capacity.
Another object of the invention is to provide a hydraulic torque converter having a modified impeller blade design for improving torque absorption capacity.
Yet another object of the invention is to provide a hydraulic torque converter having an inverted impeller blade design for improving torque absorption capacity.
Yet another object of the invention is to provide a hydraulic torque converter with enhanced torque absorption capacity without compromising the efficiency.
Yet another object of the invention is to provide a hydraulic torque converter with enhanced torque absorption capacity without increasing torus size.
SUMMARY OF INVENTION
Before the present hydraulic torque converter is described, it is to be understood that this application is not limited to the particular machine or an apparatus, and methodologies described, as there can be multiple possible embodiment that are not expressly illustrated in the present disclosure. It is also to be understood that the terminology used in the description is for the purpose of describing the particular version or embodiment only and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to a hydraulic torque converter and the aspects are further elaborated below in the detailed description. This summary is not intended to identify essential features of the proposed subject matter nor is it intended for use in determining or limiting the scope of the proposed subject matter.
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise. The expression ‘Torque ratio’ used hereinafter in the specification refers to the ratio between turbine torque to impeller torque. The expression ‘Speed Ratio’ used hereinafter in the specification refers to the ratio between turbine speed to impeller speed. The expression ‘Efficiency’ used hereinafter in the specification refers to the product of torque ratio and speed ratio. The expression ‘Torque Absorption Capacity’ used hereinafter in the specification refers to the absorption characteristics of torque converter in-terms of torque capacity.
In one implementation, the hydraulic torque converter comprises an impeller, a turbine and a stator. The impeller is configured with a modified blade design for improving the torque absorption capacity and efficiency of the hydraulic torque converter without increasing the torus size. The modified impeller blade design is configured to be an inverted blade design. Any of squash or round type hydraulic torque converter is used with the corresponding inverted impeller blade design to enhance torque absorption capacity for superior vehicle performance.

STATEMENT OF INVENTION
Accordingly, present invention discloses a hydraulic torque converter with improved torque absorption capacity. The torque converter comprises an impeller coupled to an engine output, a turbine coupled to a transmission input and a stator located between the impeller and the turbine for re-directing the fluid momentum from the turbine towards the impeller. The impeller, the turbine and the stator form a torus of the torque converter. A mean camber line is formed by the locus connecting the centres of the series of circles which are tangent to both surfaces of blade profile of the impeller. An impeller entry angle is measured from a zero-reference point on torque converter axis to the line tangent to the mean camber-line projected in the direction of flow from the entry point on the mean camber line. An impeller exit angle is measured from a zero-reference point on torque converter axis to the line tangent to the mean camber-line projected in the direction of flow from the exit point on the mean camber line. An inverted impeller blade design is configured to have the impeller entry angle less than 90 degrees and the impeller exit angle greater than 90 degrees, for a squash type hydraulic torque converter. Further, an inverted impeller blade design is configured to have the impeller entry angle greater than 90 degrees and the impeller exit angle greater than 90 degrees, for a round type hydraulic torque converter. The inverted impeller blade design of the torque converter improves torque absorption capacity and efficiency of the torque converter without increasing the torus size. The inverted impeller blade design of the torque converter improves torque absorption capacity and efficiency from stall point to maximum speed conditions with-out increasing the torus size. The inverted impeller blade design of the torque converter improves torque absorption capacity at all the speed ratios. The hydraulic torque converter protects the transmission by absorbing rotational irregularities of the engine output and also to protect the engine by absorbing abrupt variation of load. The inverted impeller blade design of the torque converter enhances torque absorption capacity for superior vehicle performance.

BRIEF DESCRIPTION OF DRAWINGS
The foregoing summary, as well as the following detailed description of embodiment, is better understood when read in conjunction with the appended drawing. For the purpose of illustrating the disclosure, however, the disclosure is not limited to the specific methods and apparatus disclosed in the document and the drawing.
The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawing to refer like features and components.
Figure 1 illustrates the schematic diagram of vehicle power train flow arrangements (100) according to present invention.
Figure 2 illustrates the sectional views for a squash type hydraulic torque converter (201) and a round type hydraulic torque converter (202) (Prior Art).
Figure 3A illustrates an exemplary conventional impeller blade design (Prior Art).
Figure 3B illustrates an inverted impeller blade design according to present invention.
Figure 4A (Prior Art) & 4B illustrates elements of conventional squash type hydraulic torque converter and elements of squash type hydraulic torque converter according to present invention respectively.
Figure 5A (Prior Art) & 5B illustrates the impeller blade design (510) for conventional squash type hydraulic torque converter and the inverted impeller blade design (520) for squash type hydraulic torque converter according to present invention respectively.
Figure 6A (Prior Art) & 6B illustrates elements of conventional round type hydraulic torque converter and elements of round type hydraulic torque converter according to present invention respectively.
Figure 7A (Prior Art) & 7B illustrates the impeller blade design (710) for conventional round type hydraulic torque converter and the inverted impeller blade design (720) for round type hydraulic torque converter according to present invention respectively.
Figure 8 illustrates torque absorption capacity and efficiency improvement for the round type hydraulic torque converter (800).
Figure 9 illustrates torque absorption capacity and efficiency improvement for the squash type hydraulic torque converter (900).
Figure 10 illustrates the torque absorption curves with engine data at heavy and normal load conditions for the round type hydraulic torque converter (1000).
Figure 11 illustrates the torque absorption curves with engine data at heavy and normal load conditions for the squash type hydraulic torque converter (11000).
Figures depict various embodiments of the present disclosure for purpose of illustration only. Only skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF INVENTION
Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words “comprising”, “having”, and “including,” and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. Although any systems similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, hydraulic torque converter are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.
Various modification to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to another embodiment. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated but is to be accorded the widest scope consistent with the principles and features described herein.
Figures 1-11 are now described using the reference numbers stated in the below table.
Reference Numeral Description
10 Engine
20 Torque Converter
20A Inverted impeller blade design
40 Planetary transmission unit
50 Differential unit or steering & brake clutch assembly unit
60 Final drive unit
100 Vehicle power train flow arrangements
201 Conventional squash type hydraulic torque converter
202 Conventional round type hydraulic torque converter
210, 250 Turbine
220, 240, 220A, 240A Impeller
230, 260 Stator
305, 305A Mean camber line
306, 306A, 307, 307A Tangent to the mean camber-line
400 Squash type torque converter as per present disclosure
510, 710 Conventional impeller blade design
520 Inverted impeller blade design for the squash type hydraulic torque converter
600 Round type torque converter as per present disclosure
720 Inverted impeller blade design for the round type hydraulic torque converter
800, 1000 A graph showing the comparison of the round type torque converter having inverted impeller blade design according to present invention with the round type torque converter having conventional impeller blade design
900, 1100 A graph showing the comparison of the squash type torque converter having inverted impeller blade design according to present invention with the squash type torque converter having conventional impeller blade design
Q1 Impeller entry angle
Q2 Impeller exit angle

The disclosure herein provides a hydraulic torque converter comprising an impeller, a turbine and a stator; wherein the impeller is provided with an inverted blade design for improving the torque absorption capacity and efficiency without increasing the torus size. The inverted impeller blade design is incorporated in any of squash or round type hydraulic torque converter to enhance torque absorption capacity for superior vehicle performance.
Figure 1 shows the vehicle power train flow arrangements (100). The power from the engine (10) is transmitted through the hydraulic oil by torque converter (20) to the planetary transmission unit (40), differential unit or steering & brake clutch assembly unit (50) and final drive unit (60) thru’ wheel or crawler in agreement with change in load. The hydraulic torque converter (20) protects the planetary transmission unit (40) by absorbing rotational irregularities of the engine output. It also protects the engine (10) by absorbing abrupt variation of load. In an embodiment, the impeller of the hydraulic torque converter (20) of the vehicle powertrain as shown in Figure 1, has an inverted impeller blade design (20A) for improving the torque absorption capacity without increasing the torus size.
Figure 3B illustrates an exemplary inverted impeller blade design according to present invention. The mean camber line (305A) also referred as design path is the locus connecting the centres of the series of circles which are tangent to both surfaces of the twisting blade profile. The design path or the mean camber-line (305A) is determined with the help of computational fluid dynamics with elimination of negative pressure from shell to core portion of impeller blade surface which is exactly equivalent to continuously varying double surface type of hydrofoil. In figure 3B, Q1 is an impeller entry angle measured from a zero-reference point on torque converter axis to the line (306A) tangent to the mean camber-line (305A) projected in the direction of flow from the entry point on the design path and Q2 is an impeller exit angle measured from a zero-reference point on torque converter axis to the line (307A) tangent to the mean camber-line projected in the direction of flow from the exit point on the design path. In inverted impeller blade design according to present invention, the impeller entry angle (Q1) is maintained lesser than 90 degrees (Acute Angle) and the impeller exit angle (Q2) is maintained greater than 90 degrees (Obtuse Angle).
Figure 4B illustrates the squash type torque converter (400) comprising an impeller (220A), a turbine (210) and a stator (230) according to present invention. Further, Figure 5B illustrates the inverted impeller blade design (520) according to present invention for the squash type hydraulic torque converter. In the inverted impeller blade design (520) according to present invention, the impeller entry angle (Q1) is maintained always lesser than 90 degrees (Acute Angle: 55 to 58 degrees) and the impeller exit angle (Q2) is maintained always greater than 90 degrees (Obtuse Angle: 124 ~ 127 degrees). The concave blade surfaces along with mean design path is shifted to next adjacent quadrant according to the present invention.
Figure 6B illustrates the round type torque converter (600) comprising an impeller (240A), a turbine (250) and a stator (260) according to present invention. Figure 7B illustrates the inverted impeller blade design (720) according to present invention for the round type hydraulic torque converter. In the inverted impeller blade design (720) according to present invention, the impeller entry angle (Q1) is maintained always greater than 90 degrees (Obtuse Angle: 95 ~ 100 degrees) and the impeller exit angle (Q2) is maintained always greater than 90 degrees (Obtuse Angle: 100~ 105). The concave blade surfaces along with mean design path is shifted to next adjacent quadrant according to the present invention.
Figure 8 illustrates a graph (800) showing the comparison of the round type torque converter having inverted impeller blade design according to present invention with the round type torque converter having conventional impeller blade design based on the parameters - torque absorption capacity and efficiency as a function of speed ratio. So, it is observed that, from stall point to maximum speed conditions, torque absorption capacity and efficiency are improved without increasing the torus size with the help of inverted impeller blade design of present invention.
Figure 9 illustrates a graph (900) showing the comparison of the squash type torque converter having inverted impeller blade design according to present invention with the squash type torque converter having conventional impeller blade design based on the parameters - torque absorption capacity and efficiency as a function of speed ratio. So, it is observed that, from stall point to maximum speed conditions, torque absorption capacity and efficiency are improved without increasing the torus size with the help of inverted impeller blade design of present invention.
Figure 10 illustrates a graph (1000) showing the comparison of the round type torque converter having inverted impeller blade design according to present invention with the round type torque converter having conventional impeller blade design based on the torque absorption curves with engine data at heavy and normal load conditions.
Figure 11 illustrates a graph (1100) showing the comparison of the squash type torque converter having inverted impeller blade design according to present invention with the squash type torque converter having conventional impeller blade design based on the torque absorption curves with engine data at heavy and normal load conditions.
The speed of the prime mover/ engine (10) increases from low idle speed to high idle speed as per throttle position. At heavy load condition, the engine speed will be locked at stall point and the hydraulic torque converter (20) absorbs the maximum engine torque as per impeller absorption capacity. Further, as the load demand decreases, torque absorption will reduce as per requirement. By using the torque converter having the inverted impeller blade design according to present invention, the torque absorption capacity is improved in comparison to the torque converter having conventional impeller blade design for round and squash type torque converter as shown in figure 10 & figure 11.
The torque absorption capacity (Ti) of the hydraulic torque converter is directly dependent on impeller blade surface position, pressure and shear force induced in impeller blade surfaces due to centrifugal force generated by fluid momentum.
Torque Absorption Capacity (T_i )=?_s¦[ r_s*(F_s^p + F_s^s)] * c
Where,
F_s^p=Pressure force acting on the impeller blade surface by fluid momentum;
F_s^s=Shear force acting on the impeller blade surface by fluid momentum;
r_s=Impeller blade surface position with respect to torque converter axis;
c = Cartesian Vector which defining the torque converter axis;
?Pressure force (F?_s^(p ))= (p_s-p_ref )*a_s;
Where,
p_s=Static pressure acting on the impeller blade surface;
p_ref=Reference pressure which acting inside the torus;
a_s = Impeller surface area vector;
?Shear force (F?_s^(s ))= (-M_s )*a_s;
Where,
M_s=Stress tensor at impeller surface;
a_s = Impeller surface area vector.
The inverted impeller blade design of present invention improves the torque absorption capacity by modifying the impeller blade surface position dimension (r_s) thereby increasing the pressure (F_s^(p ))and shear ?(F?_s^s) forces acting on the impeller blade surface by fluid momentum at different load conditions. Impeller blade exit angle plays vital role to improve the torque absorption capacity. By considering the above, present invention introduces inverted blade design to improve the torque absorption capacity without changing the impeller blade entry and exit radius. The unsteady effects due to meridional velocity is totally eliminated by modified blade design in the entry side of impeller in present invention which directly improves the torque absorption capacity. In present invention, absolute total pressure distribution at shell and core portions increases from suction to delivery side of impeller flow path area by centrifugal force which directly aids to improve the torque absorption capacity.
Accordingly, present invention discloses a hydraulic torque converter (20) with improved torque absorption capacity. The torque converter (20) comprises an impeller (220A, 240A) coupled to an engine (10) output, a turbine (210, 250) coupled to a transmission (40) input and a stator (230, 260) located between the impeller (220, 240) and the turbine (210, 250) for re-directing the fluid momentum from the turbine (210, 250) towards the impeller (220, 240). The impeller (220A, 240A), the turbine (210, 250) and the stator (230, 260) form a torus of the torque converter (20). A mean camber line (305A) is formed by the locus connecting the centres of the series of circles which are tangent to both surfaces of blade profile of the impeller (220A, 240A). An impeller entry angle (Q1) is measured from a zero-reference point on torque converter axis to the line (306A) tangent to the mean camber-line (305A) projected in the direction of flow from the entry point on the mean camber line (305A). An impeller exit angle (Q2) is measured from a zero-reference point on torque converter axis to the line (307A) tangent to the mean camber-line (305A) projected in the direction of flow from the exit point on the mean camber line (305A). An inverted impeller blade design (520) is configured to have the impeller entry angle (Q1) less than 90 degrees and the impeller exit angle (Q2) greater than 90 degrees, for a squash type hydraulic torque converter (201). Further, an inverted impeller blade design (720) is configured to have the impeller entry angle (Q1) greater than 90 degrees and the impeller exit angle (Q2) greater than 90 degrees, for a round type hydraulic torque converter (202). The inverted impeller blade design (520, 720) of the torque converter (20) improves torque absorption capacity and efficiency of the torque converter (20) without increasing the torus size. The inverted impeller blade design (520, 720) of the torque converter (20) improves torque absorption capacity and efficiency from stall point to maximum speed conditions with-out increasing the torus size. The inverted impeller blade design (520, 720) of the torque converter (20) improves torque absorption capacity at all the speed ratios. The hydraulic torque converter (20) protects the transmission (40) by absorbing rotational irregularities of the engine output and also to protect the engine (10) by absorbing abrupt variation of load. The inverted impeller blade design (520, 720) of the torque converter (20) enhances torque absorption capacity for superior vehicle performance.
Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include the following:
Some embodiments of the present subject matter enhance torque absorption capacity of a hydraulic torque converter.
Some embodiments of the present subject matter improve torque absorption capacity of a hydraulic torque converter without compromising the efficiency.
Some embodiments of the present subject matter improve torque absorption capacity of a hydraulic torque converter without increasing torus size.
Although implementations for a hydraulic torque converter with improved torque absorption capacity have been described in language specific to structural features and/or system, it is to be understood that the appended claims are not necessarily limited to the specific features described. Rather, the specific features are disclosed as examples of implementations.
,CLAIMS:
1. A hydraulic torque converter (20) with improved torque absorption capacity, wherein the torque converter (20) comprises:
an impeller (220A, 240A) coupled to an engine (10) output;
a turbine (210, 250) coupled to a transmission (40) input; and
a stator (230, 260) located between the impeller (220A, 240A) and the turbine (210, 250) for re-directing the fluid momentum from the turbine (210, 250) towards the impeller (220, 240);
wherein, the impeller (220A, 240A), the turbine (210, 250) and the stator (230, 260) are configured to form a torus of the torque converter (20);
wherein, a mean camber line (305A) is configured to be formed by the locus connecting the centres of the series of circles which are tangent to both surfaces of blade profile of the impeller (220A, 240A);
wherein, an impeller entry angle (Q1) is configured to be measured from a zero-reference point on torque converter axis to the line (306A) tangent to the mean camber-line (305A) projected in the direction of flow from the entry point on the mean camber line (305A);
wherein, an impeller exit angle (Q2) is configured to be measured from a zero-reference point on torque converter axis to the line (307A) tangent to the mean camber-line (305A) projected in the direction of flow from the exit point on the mean camber line (305A).

2. The hydraulic torque converter (20) as claimed in claim 1, wherein an inverted impeller blade design (520) is configured to have the impeller entry angle (Q1) less than 90 degrees and the impeller exit angle (Q2) greater than 90 degrees.

3. The hydraulic torque converter (20) as claimed in claim 1, wherein an inverted impeller blade design (720) is configured to have the impeller entry angle (Q1) greater than 90 degrees and the impeller exit angle (Q2) greater than 90 degrees.

4. The hydraulic torque converter (20) as claimed in claim 2, wherein the torque converter (20) is configured to be a squash type hydraulic torque converter (201).

5. The hydraulic torque converter (20) as claimed in claim 3, wherein the torque converter (20) is configured to be a round type hydraulic torque converter (202).

6. The hydraulic torque converter (20) as claimed in claim 1, wherein an inverted impeller blade design (520, 720) of the torque converter (20) is configured to improve torque absorption capacity and efficiency of the torque converter (20) without increasing the torus size.

7. The hydraulic torque converter (20) as claimed in claim 1, wherein an inverted impeller blade design (520, 720) of the torque converter (20) is configured to improve torque absorption capacity and efficiency from stall point to maximum speed conditions with-out increasing the torus size.

8. The hydraulic torque converter (20) as claimed in claim 1, wherein an inverted impeller blade design (520, 720) of the torque converter (20) is configured to improve torque absorption capacity at all the speed ratios.

9. The hydraulic torque converter (20) as claimed in claim 1, wherein the hydraulic torque converter (20) is configured to protect the transmission (40) by absorbing rotational irregularities of the engine output and also to protect the engine (10) by absorbing abrupt variation of load.

10. The hydraulic torque converter (20) as claimed in claim 1, wherein an inverted impeller blade design (520, 720) of the torque converter (20) is configured for enhancing torque absorption capacity for superior vehicle performance.