DESC:FIELD
The present disclosure relates to the field of internal combustion engines.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
In an inline three-cylinder engine a power stroke is obtained every 240 degrees of crankshaft rotation. Since the firing of the three pistons is spaced apart at 240 degrees, the unbalanced inertia force, which is maximum when one piston reaches TDC (Top Dead Centre), cannot be balanced by the inertia forces of the other two pistons which are each 240 degrees away from TDC. As a result, an unbalanced primary couple acts along the length of the crankshaft which tends to rock the crankshaft end-to-end.
Conventionally, there are two prevailing methods to counter this unbalanced couple. One method is to employ an additional balancer shaft rotating with the same speed as the crankshaft but in an opposite direction of rotation, and balance weights attached at the ends of the crankshaft. However, the balance shaft has to be supported in the engine structure by suitable bearings and a gear drive from crankshaft has to be provided. This results in a greater number of parts, increased cost and increased engine width. In some configurations, the balance shaft is located below the crankshaft to prevent the increase in engine width, but it may result in less space available for the engine lubricating oil sump. Another method is to provide unbalanced masses on the flywheel and the crank pulley (which are placed at the opposite ends of the crankshaft) to counter the rocking couple. However, the angular positioning of these masses has to be accurately placed with respect to the crank pins. If this is not ensured during the assembly and/or machining process, the engine unbalance may increase. This is detrimental to the engine structure if positioning of the flywheel and the pulley is not accurate. As a result, mishaps occur and safety of the personnel surrounding the engine is in jeopardy.
There is therefore felt a need for a crankshaft of an internal combustion engine, which alleviates the aforementioned drawbacks.
OBJECT
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide a crankshaft of an internal combustion engine.
Another object of the present disclosure is to provide a crankshaft of an internal combustion engine, which reduces rotational and reciprocating imbalance of the crankshaft.
Yet another object of the present disclosure is to provide a crankshaft of an internal combustion engine, which eliminates the need of complicated modifications.
Still another object of the present disclosure is to provide a crankshaft of an internal combustion engine, which reduces complexity of construction of the engine.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure a crankshaft of an internal combustion engine. The crankshaft comprises a plurality of crankpins configured offset to the axis of the crankshaft, a plurality of counterweights configured opposite to the crankpins. The counterweights are configured such that the counterweight centerline of a counterweight is configured to be angularly offset from the crankpin centerline of the corresponding crankpin. The counterweights are configured to reduce rotational as well as reciprocating imbalance during crankshaft motion.
In a preferred embodiment, the crankshaft is configured for a three-cylinder internal combustion engine.
In a preferred embodiment, the positioning of the counterweights eliminates need of a separate balancing shaft.
In a preferred embodiment, the counterweights are configured in a way that eliminates need of modification of a flywheel and a pulley that are configured on the ends of the crankshaft.
In a preferred embodiment, the counterweight centerline of a counterweight and the crankpin centerline of the corresponding crankpin is separated by a predetermined angle.
In an embodiment, the predetermined angle A between the counterweight centerline of a counterweight and the crankpin centerline of the corresponding crankpin is 214 degrees.
In another embodiment, the predetermined angle is different for different counterweights.
In another embodiment, each of the counterweights has a different self-weight.
In an embodiment, the face profile of each of the counterweights has a different shape.
In another embodiment, the face profile of each of the counterweights has a similar shape.
In still another embodiment, the face profiles of the counterweights have different dimensions.
In another embodiment, the face profiles of the counterweights are congruent.
In an embodiment, the counterweights are integral to the crankpins.
In an embodiment, the counterweights are removably attached to the crankpins.
In yet another embodiment, the counterweights are configured on at least one of the crankpins.
In still another embodiment, the counterweights are configured on each of the crankpins.
In an alternate embodiment, a plurality of holes not shown in figures are configured on the counterweights at predetermined locations.
In a preferred embodiment, a crank sensor wheel not shown in the figures is provided near one of the counterweights to record crank angle data of the crankshaft.
BRIEF DESCRIPTION OF DRAWING
A crankshaft of an internal combustion engine, of the present disclosure, for a three-cylinder engine will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates an isometric view of the crankshaft, in accordance with an embodiment of the prior art;
Figure 2 illustrates an isometric view of the crankshaft, in accordance with another embodiment of the prior art;
Figure 3 illustrates a side view of the crankshaft, in accordance with an embodiment of the present disclosure;
Figure 4 illustrates a front view of the crankshaft of Figure 3; and
Figure 5 illustrates a front view of a counterweight with a crankpin of the crankshaft of Figure 3.
LIST OF REFERENCE NUMERALS
100’,100’’ – crankshaft of the prior art
100 – crankshaft of the present disclosure
10 – first main journal
12 – second main journal
14 – third main journal
16 – fourth main journal
20’’, 24’’ – crank pin of the prior art
20 – first crank pin
22 – second crank pin
24 – third crank pin
30 – first crank arm
32 – second crank arm
34 – third crank arm
36 – fourth crank arm
38 – fifth crank arm
39 – sixth crank arm
40 – first counterweight
40’, 42’– additional counterweights of the prior art
40’’, 42’’ - unbalanced mass of the prior art
42 – second counterweight
44 – third counterweight
46 – fourth counterweight
X – counterweight axis
Y – crankpin axis
Z – axis of crankshaft
A – predetermined angle
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, elements, components, and/or groups thereof.
When an element is referred to as being "mounted on," “engaged to,” "connected to," or "coupled to" another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
Terms such as “inner,” “outer,” "beneath," "below," "lower," "above," "upper," and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
In an inline three-cylinder engine a power stroke is obtained every 240 degrees of crankshaft rotation. Since the firing of the three pistons is spaced apart at 240 degrees, the unbalanced inertia force, which is maximum when one piston reaches TDC (Top Dead Centre), cannot be balanced by the inertia forces of the other two pistons which are each 240 degrees away from TDC. As a result, an unbalanced primary couple acts along the length of the crankshaft 100’ which tends to rock the crankshaft 100’ end-to-end. Conventionally, there are two prevailing methods to counter this unbalanced couple.
As shown in the figure 1, a first method is to employ an additional balance shaft 110’ rotating with the same speed as the crankshaft 100’ but in an opposite direction of rotation, and additional balance weights 40’42’ attached at the ends of the additional balance shaft 110’. However, the additional balance shaft 110’ has to be supported in the engine structure by suitable bearings and a gear drive from the crankshaft 100‘ has to be provided. This results in a greater number of parts, increased cost and increased engine width. In some configurations, the additional balance shaft 110’ is located below the crankshaft 100’ to prevent the increase in engine width, but it results in less space available for the engine lubricating oil sump.
As shown in the figure 2, a second method is to provide an unbalanced mass 40’’ on the flywheel and another unbalanced mass 42’’ on the crank pulley (which are placed at the opposite ends of the crankshaft 100’’) to counter the rocking couple. However, the angular positioning of these unbalanced masses 40’’, 42’’ has to be accurately placed, with respect to the crank pins 20’’, 24’’. If this is not ensured during the assembly and/or machining process, the engine unbalance may increase.
A preferred embodiment of a crankshaft of an internal combustion engine of the present disclosure, will now be described with reference to Figure 3 through Figure 5. The embodiment does not limit the scope and ambit of the present disclosure.
As shown in the figure 3, the crankshaft 100 includes a first main journal 10, a second main journal 12, a third main journal 14 and a fourth main journal 16. The main journals 10, 12, 14, 16 are supported on main bearings (not shown in figures). The crankshaft 100 rotates inside the main bearings, which in turn support the crankshaft 100. In an embodiment, the main bearings are steel backed, with a layer of bearing material, so as to support the rotating crankshaft 100 on a film of lubricating oil under pressure. The main journals 10, 12, 14, 16 are secured into saddles (not shown in figures). Each saddle is provided with a replaceable bearing insert (not shown in figures) configured to absorb small amounts of contaminants to prevent damage to the crankshaft 100. The crankshaft 100 comprises a plurality of crankpins 20, 22, 24 are configured to support connecting rods (not shown in figures) which transfers gas pressure and inertia loads via the piston (not shown in figures). The gas pressure and inertia load from the piston result during the power stroke of the engine. Each of the crankpins 20, 22, 24 is connected to a connecting rod. The main journals 10, 12, 14, 16 and the crank pins 20, 22, 24 are connected by crank arms 30, 32, 34, 36, 38, 39. More specifically, the first crank arm 30, the second crank arm 32, the fifth crank arm 38 and the sixth crank arm 39, each have a corresponding counterweight 40, 42, 44, 46 attached thereto. Each of the crankpins 20, 22, 24 is configured offset to the axis Z of the crankshaft 100. A plurality of counterweights 40, 42, 44, 46 are configured to be attached to the crankpins 20, 22, 24. The counterweights 40, 42, 44, 46 are positioned on opposite side of the geometrical axis Z of the crankshaft 100.
Figure 4 shows a front view of the crankshaft 100 with the counterweights 40, 42, 44, 46 and the crankpins 20, 22, 24.
As shown in the figure 5, a counterweight centerline X and a crankpin centerline Y is shown. The counterweight centerline X is defined by a line passing through the centre of gravity of a counterweight 40, 42, 44, 46 and perpendicular to the geometrical axis Z of the crankshaft 100. The crankpin centerline Y is defined by a line passing through the centre of gravity of a crankpin 20, 22, 24 and perpendicular to the geometrical axis Z of the crankshaft 100. The counterweights 40, 42, 44, 46 are positioned such that the counterweight centerline X of a counterweight 40, 42, 44, 46 is configured to be angularly offset from the crankpin centerline Y of the corresponding crankpin 20, 22, 24. This facilitates reduction in rotational and reciprocating imbalance during the motion of the crankshaft 100. The rotational and reciprocating imbalance arises due to the gas pressure and the inertia loads transferred by the piston.
In a preferred embodiment, the crankshaft 100 is configured for a three-cylinder internal combustion engine, as shown in the figures 3-5.
The positioning of the counterweights 40, 42, 44, 46 eliminates need of a separate balancing shaft. Moreover, the construction of the counterweights 40, 42, 44, 46 eliminates the need of modification of a flywheel and a pulley. The flywheel and the pulley are configured on either ends of the crankshaft 100.
In one embodiment, the counterweight centerline X of a counterweight 40, 42, 44, 46 and the crankpin centerline Y of the corresponding crankpin 20, 22, 24 is separated by a predetermined angle A.
In another embodiment, the predetermined angle between the counterweight centerline X of a counterweight 40, 42, 44, 46 and the crankpin centerline Y of the corresponding crankpin 20, 22, 24 is 214 degrees.
In yet another embodiment, the predetermined angle A is different for different counterweights 40, 42, 44, 46. This is achieved by performing CAE simulation of the crankshaft 100 in an iterative manner that facilitates minimizing the rotational and reciprocating imbalance of the crankshaft 100.
In a preferred embodiment, each of the counterweights 40, 42, 44, 46 has a different self-weight so as to facilitate minimizing the rotational and reciprocating imbalance of the crankshaft 100 when the crankshaft 100 is set in motion.
In another embodiment, the face profile of each of the counterweights 40, 42, 44, 46 has a different shape. This further facilitates material distribution of the crankshaft which further facilitates in minimizing the rotational and reciprocating imbalance.
In another embodiment, the face profile of each of the counterweights 40, 42, 44, 46 has a similar shape.
In another embodiment, the face profiles of the counterweights 40, 42, 44, 46 have different dimensions. An extensive CAE analysis of the crankshaft 100 facilitates making decision regarding modification of the crankshaft 100.
In another embodiment, the face profiles of the counterweights 40, 42, 44, 46 are congruent.
In an embodiment, the counterweights 40, 42, 44, 46 are integral to the crankpins 20, 22, 24 to facilitate increased strength of the crankshaft 100.
In an embodiment, the counterweights 40, 42, 44, 46 are removably attached to the crankpins 20, 22, 24.
In an embodiment, the counterweights 40, 42, 44, 46 are configured on at least one of the crankpins 20, 22, 24.
In another embodiment, the counterweights 40, 42, 44, 46 are configured on each of the crankpins 20, 22, 24.
A plurality of holes (not shown in figures) are configured on the counterweights 40, 42, 44, 46 at predetermined locations.
Additionally, the oil retaining capacity of the crankshaft 100 increases due to relatively lesser amount of stress being applied on the bearings of the crankshaft 100.
In an embodiment, a crank sensor wheel (not shown in figures) is provided near the sixth counterweight 46 to record crank angle data of the crankshaft 100.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a crankshaft of an internal combustion engine, which:
• reduces end-to-end rocking motion of the crankshaft;
• eliminates the need of a separate parallel balancing shaft; and
• simplifies the crankshaft construction.
The embodiments herein, the various features, and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure, as it existed anywhere before the priority date of this application.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

,CLAIMS:We Claim:
1. A crankshaft (100) of an internal combustion engine, said crankshaft (100) comprising:
• a plurality of crankpins (20, 22, 24) configured on one side and offset to the axis (Z) of the crankshaft (100);
• a plurality of counterweights (40, 42, 44, 46) configured to be attached to said crankpins (20, 22, 24); said counterweights (40, 42, 44, 46) positioned on opposite side of the axis (Z) of said crankshaft (100);
wherein said counterweights (40, 42, 44, 46) are configured such that the counterweight centerline (X) of a counterweight (40, 42, 44, 46) is configured to be angularly offset from the crankpin centerline (Y) of the corresponding crankpin (20, 22, 24), said counterweights (40, 42, 44, 46) configured to reduce rotational as well as reciprocating imbalance during crankshaft motion.
2. The crankshaft (100) as claimed in claim 1, wherein said crankshaft (100) is configured for a three-cylinder internal combustion engine.
3. The crankshaft (100) as claimed in claim 1, wherein the positioning of said counterweights (40, 42, 44, 46) eliminates need of a separate balancing shaft.
4. The crankshaft (100) as claimed in claim 1, wherein said counterweights (40, 42, 44, 46) are configured in a way that eliminates need of modification of a flywheel and a pulley that are configured on the ends of said crankshaft (100).
5. The crankshaft (100) as claimed in claim 1, wherein the counterweight centerline (X) of a counterweight (40, 42, 44, 46) and the crankpin centerline (Y) of the corresponding crankpin (20, 22, 24) is separated by a predetermined angle (A).
6. The crankshaft (100) as claimed in claim 1, wherein the predetermined angle (A) between the counterweight centerline (X) of a counterweight (40, 42, 44, 46) and the crankpin centerline (Y) of the corresponding crankpin (20, 22, 24) is 214 degrees.
7. The crankshaft (100) as claimed in claim 5, wherein the predetermined angle (A) is different for different counterweights (40, 42, 44, 46).
8. The crankshaft (100) as claimed in claim 1, wherein each of said counterweights (40, 42, 44, 46) has a different self-weight.
9. The crankshaft (100) as claimed in claim 1, wherein the face profile of each of said counterweights (40, 42, 44, 46) has a different shape.
10. The crankshaft (100) as claimed in claim 1, wherein the face profile of each of said counterweights (40, 42, 44, 46) has a similar shape.
11. The crankshaft (100) as claimed in claim 1, wherein the face profiles of said counterweights (40, 42, 44, 46) have different dimensions.
12. The crankshaft (100) as claimed in claim 1, wherein the face profiles of said counterweights (40, 42, 44, 46) are congruent.
13. The crankshaft (100) as claimed in claim 1, wherein said counterweights (40, 42, 44, 46) are integral to said crankpins (20, 22, 24).
14. The crankshaft (100) as claimed in claim 1, wherein said counterweights (40, 42, 44, 46) are removably attached to said crankpins (20, 22, 24).
15. The crankshaft (100) as claimed in claim 1, wherein said counterweights (40, 42, 44, 46) are configured on at least one of said crankpins (20, 22, 24).
16. The crankshaft (100) as claimed in claim 1, wherein said counterweights (40, 42, 44, 46) are configured on each of said crankpins (20, 22, 24).
17. The crankshaft (100) as claimed in claim 1, wherein a plurality of holes (not shown in figures) are configured on said counterweights (40, 42, 44, 46) at predetermined locations.
18. The crankshaft (100) as claimed in claim 1, wherein a crank sensor wheel (not shown in the figures) is provided near one of said counterweights (40, 42, 44, 46) to record crank angle data of the crankshaft 100.
Dated this 20th day of September, 2021

___________________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant