Planetary gear train of automatic transmission for vehicle

The present application claims priority to Korean Patent Application No. 10-2018-0072641 filed on Jun. 25, 2018, the entire contents of which is incorporated herein for all purposes by this reference.

The present invention relates to an automatic transmission for a vehicle.

In the field of an automatic transmission, more multiplicity of shifting stages is useful technology for enhancement of fuel consumption and drivability of a vehicle.

In this sense, research for an engine has been made to achieve weight reduction and to enhance fuel consumption by so-called downsizing and research on an automatic transmission has been performed to simultaneously provide better drivability and fuel consumption by achieving more shifting stages.

To achieve more shifting stages for an automatic transmission, the number of parts is typically increased, which may deteriorate installability, a production cost, weight and/or power flow efficiency.

Therefore, to maximally enhance fuel consumption of an automatic transmission having more shifting stages, it is important that better efficiency is derived by less number of parts.

In this background, an eight-speed automatic transmission has been introduced recently and a planetary gear train for an automatic transmission facilitating more shifting stages is under investigation.

Furthermore, a recent eight-speed automatic transmission typically shows a gear ratio span in a level of claims 6.5 to 7.5, which may require improvement for better fuel consumption.

In the case of a gear ratio span of an eight-speed automatic transmission having a level above 9.0, it is difficult to maintain step ratios between adjacent shifting stages to be linear, by which driving efficiency of an engine and drivability of a vehicle deteriorated. Thus, research studies are underway for developing a high efficiency automatic transmission having nine or more speeds.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and may not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Various aspects of the present invention are directed to providing a planetary gear train of an automatic transmission for a vehicle facilitating at least ten forward speeds, providing better performance and fuel efficiency of a vehicle.

A planetary gear train according to an exemplary embodiment of the present invention may include an input shaft receiving an engine torque, an output shaft outputting a shifted torque, a first planetary gear set having first, second, and third rotation elements, a second planetary gear set having fourth, fifth, and sixth rotation elements, a third planetary gear set having seventh, eighth, and ninth rotation elements, a fourth planetary gear set having tenth, eleventh, and twelfth rotation elements, a fifth planetary gear set having thirteenth, fourteenth, and fifteenth rotation elements, a first shaft fixedly connected to the first rotation element, the fifth rotation element, and the input shaft, a second shaft fixedly connected to the fourteenth rotation element and the output shaft, a third shaft fixedly connected to the sixth rotation element and the tenth rotation element, a fourth shaft fixedly connected to the eighth rotation element and the fifteenth rotation element, a fifth shaft fixedly connected to the eleventh rotation element and the thirteenth rotation element, a sixth shaft fixedly connected to the twelfth rotation element, a seventh shaft fixedly connected to the third rotation element and the seventh rotation element, an eighth shaft fixedly connected to the second rotation element and the fourth rotation element, and a ninth shaft fixedly connected to the ninth rotation element.

The planetary gear train may further include six engagement elements each selectively connecting a corresponding pair among the input shaft, the output shaft, the first to ninth shafts, and the transmission housing, wherein a plurality of shifting stages is realized by engaging three engagement elements for respective shifting stage.

The six engagement elements may include three clutches each selectively connecting a corresponding pair among the first to ninth shafts, and three brakes each selectively connecting a corresponding shaft to the transmission housing.

The three clutches may include a first clutch disposed between the first shaft and the sixth shaft, a second clutch disposed between the third shaft and the sixth shaft, and a third clutch disposed between the fourth shaft and the fifth shaft.

The three brakes may include a first brake disposed between the seventh shaft and the transmission housing, a second brake disposed between the eighth shaft and the transmission housing, and a third brake disposed between the ninth shaft and the transmission housing.

The first, second, and third rotation elements may be a first sun gear, a first planet carrier, and a first ring gear, respectively of the first planetary gear set. The fourth, fifth, and sixth rotation elements may be a second sun gear, a second planet carrier, and a second ring gear, respectively of the second planetary gear set. The seventh, eighth, and ninth rotation elements may be a third sun gear, a third planet carrier, and a third ring gear, respectively of the third planetary gear set. The tenth, eleventh, and twelfth rotation elements may be a fourth sun gear, a fourth planet carrier, and a fourth ring gear of the fourth planetary gear set, respectively. The thirteenth rotation element, the fourteenth rotation element, and the fifteenth rotation element may be a fifth sun gear, a fifth planet carrier, and a fifth ring gear of the fifth planetary gear set, respectively.

The first, second, third, fourth, and fifth planetary gear sets may be disposed in an order of the first, second, third, fourth, and fifth planetary gear sets from an engine side thereof.

A planetary gear train according to an exemplary embodiment of the present invention may realize at least ten forward speeds and at least one reverse speed formed by operating the five planetary gear sets of simple planetary gear sets by controlling six engagement elements.

Furthermore, a planetary gear train according to an exemplary embodiment of the present invention may realize a gear ratio span of more than 9.0, maximizing efficiency of driving an engine.

While employing five planetary gear sets for ten forward speeds and one reverse speed, engagement elements are minimally employed, reducing drag loss of clutches and brakes, and accordingly improving power delivery efficiency and fuel consumption.

Furthermore, a torque-in-parallel scheme is applied to an output-side planetary gear set, and thereby torque loads of planetary gear sets and engagement elements may become more uniform, such that torque delivery efficiency and durability may be enhanced.

While realizing ten forward speeds and one reverse speed, flexibility of output gear ratio is increased, enhancing linearity of step ratios of shifting stages.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which in combination serve to explain certain principles of the present invention.

FIG. 1 is a schematic diagram of a planetary gear train according to an exemplary embodiment of the present invention.

FIG. 2 is an operation chart for respective control elements at respective shifting stage applicable to a planetary gear train according to an exemplary embodiment of the present invention.

It may be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as included herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particularly intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments of the present invention, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments of the present invention, but various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to drawings.

The drawings and description are to be regarded as illustrative in nature and not restrictive, and like reference numerals designate like elements throughout the specification.

In the following description, dividing names of components into first, second, and the like is configured to divide the names because the names of the components are the same as each other and an order thereof is not particularly limited.

FIG. 1 is a schematic diagram of a planetary gear train according to an exemplary embodiment of the present invention.

Referring to FIG. 1 , a planetary gear train according to an exemplary embodiment of the present invention includes first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 disposed on a same axis, an input shaft IS, an output shaft OS, nine shafts TM 1 to TM 9 interconnecting rotation elements of the first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 , engagement elements of three clutches Cl to C 3 and three brakes B 1 to B 3 , and a transmission housing H.

A torque received from an engine through the input shaft IS is changed by cooperative operation of the first, second, third, fourth, and fifth planetary gear sets PGI, PG 2 , PG 3 , PG 4 , and PG 5 , and a shifted torque is output through the output shaft OS.

In an exemplary embodiment of the present invention, the planetary gear sets are disposed in the order of the first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 , from an engine side thereof, i.e., from an input side thereof.

The input shaft IS is an input member and the torque from a crankshaft of an engine is input into the input shaft IS, after being torque-converted through a torque converter.

The output shaft OS is an output element disposed on a same axis with the input shaft IS, and outputs a shifted driving torque to a driveshaft through a differential apparatus.

The first planetary gear set PG 1 is a single pinion planetary gear set, and includes a first sun gear S 1 , a first planet carrier PC 1 rotatably supporting a plurality of first pinion gears P 1 externally gear-meshed with the first sun gear S 1 , and a first ring gear R 1 internally gear-meshed with the plurality of first pinion gears P 1 . The first sun gear S 1 acts as a first rotation element N 1 , the first planet carrier PC 1 acts as a second rotation element N 2 , and the first ring gear R 1 acts as a third rotation element N 3 .

The second planetary gear set PG 2 is a single pinion planetary gear set, and includes a second sun gear S 2 , a second planet carrier PC 2 rotatably supporting a plurality of second pinion gears P 2 externally gear-meshed with the second sun gear S 2 , and a second ring gear R 2 internally gear-meshed with the plurality of second pinion gears P 2 . The second sun gear S 2 acts as a fourth rotation element N 4 , the second planet carrier PC 2 acts as a fifth rotation element N 5 , and the second ring gear R 2 acts as a sixth rotation element N 6 .

The third planetary gear set PG 3 is a single pinion planetary gear set, and includes a third sun gear S 3 , a third planet carrier PC 3 rotatably supporting a plurality of third pinion gears P 3 externally gear-meshed with the third sun gear S 3 , and a third ring gear R 3 internally gear-meshed with the plurality of third pinion gears P 3 . The third sun gear S 3 acts as a seventh rotation element N 7 , the third planet carrier PC 3 acts as an eighth rotation element N 8 , and the third ring gear R 3 acts as a ninth rotation element N 9 .

The fourth planetary gear set PG 4 is a single pinion planetary gear set, and includes a fourth sun gear S 4 , a fourth planet carrier PC 4 rotatably supporting a plurality of fourth pinion gears P 4 externally gear-meshed with the fourth sun gear S 4 , and a fourth ring gear R 4 internally gear-meshed with the plurality of fourth pinion gears P 4 . The fourth sun gear S 4 acts as a tenth rotation element N 10 , the fourth planet carrier PC 4 acts as an eleventh rotation element N 11 , and the fourth ring gear R 4 acts as a twelfth rotation element N 12 .

The fifth planetary gear set PG 5 is a single pinion planetary gear set, and includes a fifth sun gear S 5 , a fifth planet carrier PC 5 rotatably supporting a plurality of fifth pinion gears P 5 externally gear-meshed with the fifth sun gear S 5 , and a fifth ring gear R 5 internally gear-meshed with the plurality of fifth pinion gears P 5 . The fifth sun gear S 5 acts as a thirteenth rotation element N 13 , the fifth planet carrier PC 5 acts as a fourteenth rotation element N 14 , and the fifth ring gear R 5 acts as a fifteenth rotation element N 15 .

In the first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 , the first rotation element N 1 and the fifth rotation element N 5 are fixedly interconnected, the second rotation element N 2 and the fourth rotation element N 4 are fixedly interconnected, the third rotation element N 3 and the seventh rotation element N 7 are fixedly connected, the sixth rotation element N 6 and the tenth rotation element N 10 are fixedly connected, the eighth rotation element N 8 and the fifteenth rotation element N 15 are fixedly connected, the eleventh rotation element N 11 and the thirteenth rotation element N 13 are fixedly interconnected, and nine shafts TM 1 to TM 9 are formed.

The nine shafts TM 1 to TM 9 are hereinafter described in detail.

The first shaft TM 1 is fixedly connected to the first rotation element N 1 (first sun gear S 1 ) and the fifth rotation element N 5 (second planet carrier PC 2 ), and fixedly connected to the input shaft IS, always acting as an input element.

The second shaft TM 2 is fixedly connected to the fourteenth rotation element N 14 (fifth planet carrier PC 5 ), and fixedly connected to the output shaft OS thereby always acting as an output element.

The third shaft TM 3 is fixedly connected to the sixth rotation element N 6 (second ring gear R 2 ) and the tenth rotation element N 10 (fourth sun gear S 4 ).

The fourth shaft TM 4 is fixedly connected to the eighth rotation element N 8 (third planet carrier PC 3 ) and the fifteenth rotation element N 15 (fifth ring gear R 5 ).

The fifth shaft TM 5 is fixedly connected to the eleventh rotation element N 11 (fourth planet carrier PC 4 ) and the thirteenth rotation element N 13 (fifth sun gear S 5 ).

The sixth shaft TM 6 is fixedly connected to the twelfth rotation element N 12 (fourth ring gear R 4 ).

The seventh shaft TM 7 is fixedly connected to the third rotation element N 3 (first ring gear) and the seventh rotation element N 7 (third sun gear S 3 ).

The eighth shaft TM 8 is fixedly connected to the second rotation element N 2 (first planet carrier PC 1 ) and the fourth rotation element N 4 (second sun gear S 2 ).

The ninth shaft TM 9 is fixedly connected to the ninth rotation element N 9 (third ring gear R 3 ).

Each of the nine shafts TM 1 to TM 9 may be a rotation member that fixedly interconnects the input and output shafts and rotation elements of the planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PGS, or may be a rotation member that selectively interconnects a rotation element to the transmission housing H, or may be a fixed member fixed to the transmission housing H.

In the disclosure, when two or more members are described to be “fixedly connected”, where the member may be any of a shaft, an input shaft, an output shaft, a rotation member, and a transmission housing, it means that the fixedly connected members always rotate at a same speed.

When two or more members are described to be “selectively connectable” by an engagement element, it means that the selectively connectable members rotate separately when the engagement element is not engaged, and rotates at a same speed when the engagement element is engaged. It may be understood that in the case that a member is “selectively connectable” with a transmission housing by an engagement element, the member may be stationary when the engagement element is engaged.

The first shaft TM 1 and the third shaft TM 3 are selectively connectable to the sixth shaft TM 6 , and the fourth shaft TM 4 is selectively connectable to the fifth shaft TM 5 .

Furthermore, the seventh shaft TM 7 , the eighth shaft TM 8 , and ninth shaft TM 9 are selectively connectable to the transmission housing H, selectively acting as a fixed element.

Three engagement elements of clutches C 1 , C 2 , and C 3 are disposed between the nine shafts TM 1 to TM 9 , the input shaft IS, and the output shaft OS, to form selective connections.

Three engagement elements of brakes B 1 , B 2 , and B 3 are disposed between the nine shafts TM 1 to TM 9 and the transmission housing H, to form selective connections.

The six engagement elements of the three clutches C 1 to C 3 and the three brakes B 1 to B 3 are disposed as follows.

The first clutch C 1 is disposed between the first shaft TM 1 and the sixth shaft TM 6 , and selectively connects the first shaft TM 1 and the sixth shaft TM 6 , controlling power delivery therebetween.

The second clutch C 2 is disposed between the third shaft TM 3 and the sixth shaft TM 6 , and selectively connects the third shaft TM 3 and the sixth shaft TM 6 , controlling power delivery therebetween.

The third clutch C 3 is disposed between the fourth shaft TM 4 and the fifth shaft TM 5 , and selectively connects the fourth shaft TM 4 and the fifth shaft TM 5 , controlling power delivery therebetween.

The first brake B 1 is disposed between the seventh shaft TM 7 and the transmission housing H, and selectively connects the seventh shaft TM 7 to the transmission housing H.

The second brake B 2 is disposed between the eighth shaft TM 8 and the transmission housing H, and selectively connects the eighth shaft TM 8 to the transmission housing H.

The third brake B 3 is disposed between the ninth shaft TM 9 and the transmission housing H, and selectively connects the ninth shaft TM 9 to the transmission housing H.

The engagement elements of the first, second, and third clutches C 1 , C 2 , and C 3 and the first, second, and third brakes B 1 , B 2 , and B 3 may be realized as multi-plate hydraulic pressure friction devices that are frictionally engaged by hydraulic pressure, however, it may not be understood to be limited thereto, since various other configuration that are electrically controllable may be available.

FIG. 2 is an operation chart for respective control elements at respective shifting stage applicable to a planetary gear train according to an exemplary embodiment of the present invention.

Referring to FIG. 2 , a planetary gear train according to an exemplary embodiment of the present invention realizes ten forward speeds and one reverse speed by operating three engagements among the first, second, and third clutches C 1 , C 2 , and C 3 and first, second, third brake B 1 , B 2 , and B 3 .

In the first forward speed D 1 , the first clutch C 1 and the first and third brakes B 1 and B 3 are simultaneously operated.

As a result, the first shaft TM 1 and the sixth shaft TM 6 are connected by the operation of the first clutch C 1 . In the instant state, the input torque is input to the first shaft TM 1 and the sixth shaft TM 6 .

In such a state, the seventh and ninth shafts TM 7 and TM 9 act as fixed elements by the operation of the first and third brakes B 1 and B 3 , realizing the first forward speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

In the second forward speed D 2 , the second clutch C 2 and the first and third brakes B 1 and B 3 are simultaneously operated.

As a result, the third shaft TM 3 and the sixth shaft TM 6 are connected by the operation of the second clutch C 2 . In the instant state, the input torque is input to the first shaft TM 1 .

In such a state, the seventh and ninth shafts TM 7 and TM 9 act as fixed elements by the operation of the first and third brakes B 1 and B 3 , realizing the second forward speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

In the third forward speed D 3 , the second clutch C 2 and the second and third brakes B 2 and B 3 are simultaneously operated.

As a result, the third shaft TM 3 and the sixth shaft TM 6 are connected by the operation of the second clutch C 2 . In the instant state, the input torque is input to the first shaft TM 1 .

In such a state, the eighth and ninth shafts TM 8 and TM 9 act as fixed elements by the operation of the second and third brakes B 2 and B 3 , realizing the third forward speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

In the fourth forward speed D 4 , the first and second clutch C 1 and C 2 and the third brake B 3 are simultaneously operated.

As a result, the first shaft TM 1 and the sixth shaft TM 6 are connected by the operation of the first clutch Cl, and the third shaft TM 3 and the sixth shaft TM 6 are connected by the operation of the second clutch C 2 . In the instant state, the input torque is input to the first shaft TM 1 and the sixth shaft TM 6 .

Furthermore, the ninth shaft TM 9 acts as a fixed element by the operation of the third brake B 3 , realizing the fourth forward speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

In the fifth forward speed D 5 , the second and third clutches C 2 and C 3 and the third brake B 3 are simultaneously operated.

As a result, the third shaft TM 3 and the sixth shaft TM 6 are connected by the operation of the second clutch C 2 , and the fourth shaft TM 4 and the fifth shaft TM 5 are connected by the operation of the third clutch C 3 . In the instant state, the input torque is input to the first shaft TM 1 .

Furthermore, the ninth shaft TM 9 acts as a fixed element by the operation of the third brake B 3 , realizing the fifth forward speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

In the sixth forward speed D 6 , the first and third clutches Cl and C 3 and the third brake B 3 are simultaneously operated.

As a result, the first shaft TM 1 and the sixth shaft TM 6 are connected by the operation of the first clutch C 1 , and the fourth shaft TM 4 and the fifth shaft TM 5 are connected by the operation of the third clutch C 3 . In the instant state, the input torque is input to the first shaft TM 1 and the sixth shaft TM 6 .

Furthermore, the ninth shaft TM 9 acts as a fixed element by the operation of the third brake B 3 , realizing the sixth forward speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

In the seventh forward speed D 7 , the first, second, and third clutches C 1 , C 2 , and C 3 are simultaneously operated.

As a result, the first shaft TM 1 and the sixth shaft TM 6 are connected by the operation of the first clutch C 1 , the third shaft TM 3 and the sixth shaft TM 6 are connected by the operation of the second clutch C 2 , and the fourth shaft TM 4 and the fifth shaft TM 5 are connected by the operation of the third clutch C 3 .

As such, the first, second, third, fourth, and fifth planetary gear sets PG 1 , PG 2 , PG 3 , PG 4 , and PG 5 integrally rotate, and when the input torque is input to the first shaft TM 1 and the sixth shaft TM 6 , the input torque is output as inputted, realizing the seventh forward speed and outputting a shifted torque through the output shaft OS connected to the second shaft TM 2 .

In the eighth forward speed D 8 , the first and third clutches Cl and C 3 and the second brake B 2 are simultaneously operated.

As a result, the first shaft TM 1 and the sixth shaft TM 6 are connected by the operation of the first clutch C 1 , and the fourth shaft TM 4 and the fifth shaft TM 5 are connected by the operation of the third clutch C 3 . In the instant state, the input torque is input to the first shaft TM 1 and the sixth shaft TM 6 .

Furthermore, the eighth shaft TM 8 acts as a fixed element by the operation of the second brake B 2 , realizing the eighth forward speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

In the ninth forward speed D 9 , the second and third clutches C 2 and C 3 and the second brake B 2 are simultaneously operated.

As a result, the third shaft TM 3 and the sixth shaft TM 6 are connected by the operation of the second clutch C 2 , and the fourth shaft TM 4 and the fifth shaft TM 5 are connected by the operation of the third clutch C 3 . In the instant state, the input torque is input to the first shaft TM 1 .

Furthermore, the eighth shaft TM 8 acts as a fixed element by the operation of the second brake B 2 , realizing the ninth forward speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

In the tenth forward speed D 10 , the second and third clutches C 2 and C 3 and the first brake B 1 are simultaneously operated.

As a result, the third shaft TM 3 and the sixth shaft TM 6 are connected by the operation of the second clutch C 2 , and the fourth shaft TM 4 and the fifth shaft TM 5 are connected by the operation of the third clutch C 3 . In the instant state, the input torque is input to the first shaft TM 1 .

Furthermore, the seventh shaft TM 7 acts as a fixed element by the operation of the first brake B 1 , realizing the tenth forward speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

In the reverse speed REV, the third clutch C 3 and the first and third brakes B 1 and B 3 are simultaneously operated.

As a result, the fourth shaft TM 4 and the fifth shaft TM 5 are connected by the operation of the third clutch C 3 . In the instant state, the input torque is input to the first shaft TM 1 .

In such a state, the seventh and ninth shafts TM 7 and TM 9 act as fixed elements by the operation of the first and third brakes B 1 and B 3 , realizing the reverse speed and outputting a shifted torque to the output shaft OS connected to the second shaft TM 2 .

As described above, a planetary gear train according to an exemplary embodiment of the present invention may realize at least ten forward speeds and at least one reverse speeds by controlling engagement elements of three clutches and three brakes to five planetary gear sets.

Furthermore, a planetary gear train according to an exemplary embodiment of the present invention may realize a gear ratio span of more than 9.0, maximizing efficiency of driving an engine.

While realizing ten forward speeds and one reverse speed, engagement elements are minimally employed, reducing drag loss of clutches and brakes, and accordingly improving power delivery efficiency and fuel consumption.

Furthermore, a torque-in-parallel scheme is applied to an output-side planetary gear set, and thereby torque loads of planetary gear sets and engagement elements may become more uniform, such that torque delivery efficiency and durability may be enhanced.

While employing five planetary gear sets for ten forward speeds and one reverse speed, flexibility of output gear ratio is increased, enhancing linearity of step ratios of shifting stages.

For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner”, “outer”, “up”, “down”, “upper”, “lower”, “upwards”, “downwards”, “front”, “rear”, “back”, “inside”, “outside”, “inwardly”, “outwardly”, “internal”, “external”, “inner”, “outer”, “forwards”, and “backwards” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described to explain certain principles of the present invention and their practical application, to enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the present invention be defined by the Claims appended hereto and their equivalents.