Patent Application
20140274539
The present invention relates to methods and systems for continuously variable transmissions. More particularly, the present invention relates to methods and systems relating to fully geared single input adaptive continuously variable transmissions.
In general, in a transmission, speed change is done by selecting one of a number of predetermined gear ratios which creates inefficiencies. Conventional continuously variable transmissions use belts and cones, hydraulics, and ratchets which have a very complicated structures, are expensive to fabricate, and are limited due to their low load capacity and high wear potential.
The present invention addresses the drawbacks described above. The present invention for the first time provides an adaptable, fully geared, continuously variable transmission (CVT) which does not use complicated mechanisms, automatically responds to input or output load changes, transmits torque smoothly, and changes gear ratio steplessly. In the past, continuously variable transmissions that use compound planetary gear sets used two power inputs and/or elaborate split power controls systems to change gear ratio. In contrast, the present invention only has one power input and there are no control systems required. The transmission automatically adapts to changes in input power and/or changes in the power output requirements due to a novel integrated gearing configuration between three planetary gear sets.
The present invention provides an adaptive continuously variable transmission (CVT) constructed in such a way that it can automatically adjust gear ratio in response to changes in power to an input shaft, and to the load applied to the output shaft while still transmitting power to the output shaft. The transmission blends three compound planetary gear sets together so that the instantaneous difference in rotational speed between the input and output shafts sets the gear ratio and torque output of the transmission.
In one aspect, the transmission utilizes a one-way bearing clutch to prevent free-spinning of the internal gears of the transmission.
In another aspect, an adaptive continuously variable transmission utilizes three Planetary Gear Sets (PGS-1, PGS-2, and PGS-3), which have common Planet Carriers (PC), Ring Gears (RG), and Sun Gears (SG). The power inputted to PGS-1 (PC) transmits to the output shaft, which is PGS-2 (SG). A one-way clutch, which allows free-spin in one direction, is incorporated into PGS-2 (PC). Other benefits and advantages of the present invention will become apparent from the disclosure, claims and drawings herein.
While the novel features of the invention are set forth with particularity in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings, in which:
In the drawings, identical reference numbers identify similar elements or components. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not drawn to scale, and some of these elements are arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn, are not intended to convey any information regarding the actual shape of the particular elements, and have been solely selected for ease of recognition in the drawings.
The following disclosure describes several methods and systems for a fully geared single input adaptive continuously variable transmission. Several features of methods and systems in accordance with example embodiments are set forth and described in the Figures. It will be appreciated that methods and systems in accordance with other example embodiments can include additional procedures or features different than those shown in the Figures. Example embodiments are described herein. However, it will be understood that these examples are for the purpose of illustrating the principles, and that the invention is not so limited.
Additionally, methods and systems in accordance with several example embodiments may not include all of the features shown in these Figures. Throughout the Figures, identical reference numbers refer to similar or identical components or procedures.
Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
Reference throughout this specification to “one example” or “an example embodiment,” “one embodiment,” “an embodiment” or various combinations or variations of these terms means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
Generally, as used herein, the following terms have the following meanings when used within the context of continuously variable transmission apparatus and systems:
“CC” means the direction of clockwise rotation when viewed from the right side of the figures. Inversely, rotation in the opposite direction or counterclockwise is defined as “CCW”. Lack of rotation in either clockwise or counterclockwise is denoted as “NEG”.
“Operably linked” is understood as a connection, either physical, mechanical or electronic, between two components of the device, or a component of the device and a gear, linkage, remote sensor, data collector, controller, computer, or the like such that the components operate together as desired.
As used herein, “plurality” is understood to mean more than one. For example, a plurality refers to at least two, three, four, five, ten, 25, 50, 75, 100, or more.
Referring now to
A first planetary gear set PGS-1 is a differential that includes a first planet carrier (PC) 2 including a first ring gear (RG) 3 and a first sun gear (SG) 4. The first ring gear (RG) 3 meshes with a first idler gear 5. The first sun gear (SG) 4 meshes with a second idler gear 6, which meshes with a third idler gear 7. A first bearing 25 encompasses a portion of a first support arm 30 which is, in turn, connected to a stator at a first end. At a second end support arm 30 is connected to second idler gear 6. Support arm 30 has a second arm 31 connected to the third idler gear 7. In one useful example embodiment the first RG 3 and the first SG 4 comprise bevel gears having of the same size.
A second planetary gear set PGS-2 includes a first planet gear 11 coupled to a shaft 32 which runs through a second bearing 27, connected to a second planet carrier PC 10, and is rigidly connected to a second planet gear 12. A fourth idler gear 13 meshes to the second planet gear 12 and a second sun gear 15. The first planet gear 11 is meshed with the combination gear 14. First and second planet gears 11, 12 rotate together to provide a gear reduction since the first planet gear 11 is larger than the second planet gear 12. A one-way clutch 9 is attached to the planet carrier PGS-2 10. When engaged to ground PC 10, the one-way clutch 9 allows free-spin in one direction and prevents rotation in the opposite direction. In one example the clutch may advantageously comprise a one-way bearing clutch.
A third planetary gear set PGS-3 is a differential that includes a third ring gear (RG) 8 coupled to an output shaft 16. The output shaft 16 is also coupled to the second sun gear PGS-3 (SG) 15. The third ring gear PGS-3 (RG) 8 also meshes with the combination gear 14. In one useful example embodiment the second RG 8 is a bevel gear. These types of components are well known in the art such that a more elaborate description is not believed necessary for those skilled in the art.
Referring now to
The continuously variable transmission can be used in any piece of equipment in which speed changes and output force varies. Fabrication of the CVT would be best accomplished through standard transmission assembly techniques since the CVT is fully geared, positive displacement, with no friction components. For this example motor vehicles will be used for describing the transmission operation. Also, for convenience, the direction of clockwise rotation when viewed from the right side of the figures, is taken as the direction of the input shaft “CC”. Inversely, rotation in the opposite direction or counterclockwise is defined as “CCW”. Lack of rotation in either clockwise or counterclockwise is denoted as “NEG”.
Referring again to
Referring now to
W5=W1*(E/(1+E))+W6*(1/(1+E)) Equation 1
W4=W5*(1/(1+D))+W6*(D/(1+D)) Equation 2
W3=W1*(1+A)−W2*A Equation 3
W2=−W4*(1/B) Equation 4
W3=W5*(1/C) Equation 5
Combining Equations 3, 4, and 5 yields:
W5*(1/C)=W1*(1+A)+W4*(1/B)A
W5*(1/C)=W1*(1+A)+[W5*(1/(1+D))+W6*(D/(1+D))]*(A/B)
(Insert Equation 4 for W4)
W5*(1/C)=W1*(1+A)+W5*(A/(B+BD))+W6*(AD/(B+BD))
W5*(1/C)−W5*(A/(B+BD))=W1*(1+A)+W6*(AD/(B+BD))
W5*[(−AC+B+BD)/(BC+BCD)]=W1*(1+A)+W6*(AD/(B+BD))
W5=[W1*(1+A)+W6*(AD/(B+BD))]/[(−AC+B+BD)/(BC+BCD)]
W5=W1*(1+A)*[(BC+BCD)/(−AC+B+BD)]+W6*(AD/(B+BD))*[(BC+BCD)/(−AC+B+BD)]
W5=W1*(E/(1+E))+W6*(1/(1+E)) Equation 1
Therefore:
(1/(1+E))=(AD/(B+BD)))*[(BC+BCD)/(−AC+B+BD)] Equation 6
E*(1/(1+E))=(1+A)*[(BC+BCD)/(−AC+B+BD)] Equation 7
E*(AD/(B+BD))*=(1+A)*
E*(AD/(B+BD))=(1+A)
E=(1+A)*((B+BD)/AD)
For the example, planetary gear sets PGS-1 and PGS-3 are differentials and therefore their gear ratios are 1 and the following gear ratios for B, C, and D can be used for the example and the gear train will not bind. Should PGS-1 and PGS-3 not be differentials as in
The invention has been described herein in considerable detail in order to comply with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles of the present invention, and to construct and use such exemplary and specialized components as are required. However, it is to be understood that the invention may be carried out by specifically different equipment, and devices, and that various modifications, both as to the equipment details and operating procedures, may be accomplished without departing from the true spirit and scope of the present invention.
