Patent Application
20190323390
The present disclosure relates to variable compression ratio technologies in internal combustion engines, and relates to ways to carry out compression ratio variation.
Variable compression ratio (VCR) technologies are employed in internal combustion engines in order to make changes to compression ratios established in combustion chambers amid engine operation. The changes are generally made in response to loads encountered during operation. In automobiles, VCR technologies have been shown to improve fuel efficiency by, for instance, operating the engine with higher compression ratios at lower loads. The technologies can be used in four-stroke and two-stroke engine strategies. One type of VCR technology makes use of a multi-link construction linking an engine piston and engine crankshaft, and makes use of an eccentric shaft.
In an embodiment, an engine variable compression ratio arrangement may include a sun gear, multiple planet gears, a ring gear, a planet gear carrier, and an actuator. The sun gear receives rotational drive input from an engine crankshaft. The planet gears are engaged with the sun gear. The ring gear is engaged with the planet gears and transmits rotational drive output to an eccentric shaft. The planet gear carrier supports rotation of the planet gears. And the actuator is coupled to the planet gear carrier. Upon actuation of the actuator, the rotational position of the planet gear carrier is altered which, in turn, shifts the rotational position of the eccentric shaft relative to the rotational position of the engine crankshaft for carrying out compression ratio variation.
In an embodiment, the engine variable compression ratio arrangement further includes a first gear that is mounted to the engine crankshaft. The first gear rotates with the engine crankshaft and is engaged with the sun gear.
In an embodiment, the sun gear includes a first set of teeth and a second set of teeth. The first set of teeth resides radially outboard of the second set of teeth. The first set of teeth is engaged with a first gear that is mounted to the engine crankshaft, and the second set of teeth is engaged with the planet gears.
In an embodiment, the engine variable compression ratio arrangement further includes a second gear that is mounted to the eccentric shaft. The second gear rotates with the eccentric shaft and is engaged with the ring gear.
In an embodiment, when the rotational position of the planet gear carrier is not altered by the actuator, the rotational position of the planet gear carrier remains stationary.
In an embodiment, the sun gear, planet gears, ring gear, and planet gear carrier together constitute a planetary gear set. The planetary gear set is configured about a primary axis. The actuator is situated generally in axial alignment with the primary axis.
In an embodiment, a first total axial length defined along the primary axis by the planetary gear set and by the actuator is less than a second total axial length defined along an engine crankshaft axis of the engine crankshaft.
In an embodiment, the sun gear, planet gears, and ring gear effect a speed reduction from the engine crankshaft to the eccentric shaft. The sun gear, planet gears, and ring gear also effect a torque increase from the engine crankshaft to the eccentric shaft.
In an embodiment, the engine variable compression ratio arrangement further includes a first gear and a second gear. The first gear is mounted to the engine crankshaft, and the second gear is mounted to the eccentric shaft. The first and second gear do not directly engage with each other.
In an embodiment, the sun gear, planet gears, ring gear, and planet gear carrier together constitute a planetary gear set. The planetary gear set is configured about a primary axis. The engine crankshaft is configured about an engine crankshaft axis. And the eccentric shaft is configured about an eccentric shaft axis. The primary axis, engine crankshaft axis, and eccentric axis are non-concentric with respect to one another.
In an embodiment, the actuator is an electric motor.
In an embodiment, an internal combustion engine includes the engine variable compression ratio arrangement.
In an embodiment, an engine variable compression ratio arrangement may include a planetary gear set, a first gear, and a second gear. The first gear transmits rotational drive output to the planetary gear set. The first gear is mounted to an engine crankshaft and rotates with the engine crankshaft. The second gear receives rotational drive input from the planetary gear set. The second gear is mounted to an eccentric shaft and rotates with the eccentric shaft. The eccentric shaft carries a variable compression ratio multi-link assembly. The planetary gear set effects a speed reduction from the first gear of the engine crankshaft to the second gear of the eccentric shaft, and effects a torque increase from the first gear of the engine crankshaft to the second gear of the eccentric shaft.
In an embodiment, the planetary gear set effects shifting of the rotational position of the eccentric shaft relative to the rotational position of the engine crankshaft in order to vary the compression ratio by way of the variable compression ratio multi-link assembly.
In an embodiment, a primary axis of the planetary gear set, an engine crankshaft axis of the engine crankshaft, and an eccentric shaft axis of the eccentric shaft are non-concentric with respect to one another.
In an embodiment, the engine variable compression ratio arrangement further includes an actuator. The actuator is coupled to the planetary gear set. Actuation of the actuator causes the rotational position of the eccentric shaft to shift relative to the rotational position of the engine crankshaft. This shifting varies the compression ratio by way of the variable compression ratio multi-link assembly.
In an embodiment, the planetary gear set includes a sun gear, multiple planet gears, and a ring gear. The sun gear is engaged with the first gear. The planet gears are engaged with the sun gear. And the ring gear is engaged with the planet gears, and is engaged with the second gear.
In an embodiment, the planetary gear set is configured about a primary axis. An actuator is coupled to the planetary gear set and is configured about the primary axis. An engine oil pump is configured about the primary axis. A first total axial length is defined along the primary axis by the planetary gear set, by the actuator, and by the engine oil pump. A second total axial length is defined along an engine crankshaft axis of the engine crankshaft. The first total axial length is less than the second total axial length.
In an embodiment, an engine variable compression ratio arrangement may include a planetary gear set and an actuator. The planetary gear set includes a sun gear, planet gears, a ring gear, and a planet gear carrier. The sun gear receives rotational drive input from an engine crankshaft. The planet gears are engaged with the sun gear. The ring gear is engaged with the planet gears and transmit rotational drive output to an eccentric shaft. The planet gear carrier supports rotation of the planet gears. The actuator is coupled to the planet gear carrier. Actuation of the actuator alters the rotational position of the planet gear carrier which, in turn, shifts the rotational position of the eccentric shaft relative to the rotational position of the engine crankshaft for compression ratio variation. The planetary gear set effects a torque increase from the engine crankshaft to the eccentric shaft. The planetary gear set, engine crankshaft, and eccentric shaft are configured about different axes with respect to one another.
In an embodiment, the planetary gear set is configured about a primary axis. The actuator is configured about the primary axis. A first total axial length is defined along the primary axis by the planetary gear set and by the actuator. A second total axial length is defined along an engine crankshaft axis of the engine crankshaft. The first total axial length is less than the second total axial length.
One or more aspects of the disclosure will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and wherein:
Referring to the drawings, an engine variable compression ratio arrangement is designed and constructed to furnish high torque phasing for variable compression ratio (VCR) technologies, while satisfying packaging demands in internal combustion engine applications. In the embodiment presented, a planetary gear set is used to carry out the phasing functionality of VCR systems. The engine variable compression ratio arrangement effects a necessary speed reduction and torque increase, and has a relatively compact configuration that does not add to the overall package length of the associated internal combustion engine. By providing these advancements, as well as others set forth below, VCR technologies can be more effectively and efficiently employed in internal combustion engines. The engine variable compression ratio arrangement is described below in the context of an automotive application, yet could be equipped in non-automotive applications as well.
Referring now to
The engine oil pump 14 is situated below the engine crankshaft 12 in terms of the overall architecture of the internal combustion engine 10. Referring now particularly to
The internal combustion engine 10 further includes an engine variable compression ratio (VCR) arrangement 44. The engine VCR arrangement 44 is a multi-piece assembly with components that work together to provide the high torque phasing required to vary the compression ratio of the internal combustion engine 10 amid engine operation, and does so with a relatively compact configuration that does not enlarge the overall package length of the internal combustion engine 10. The engine VCR arrangement 44 can have different designs, constructions, and components in different embodiments depending upon, among other factors, the designs and constructions and components of the associated internal combustion engine in which the engine VCR arrangement 44 is equipped. In the embodiment of the figures, the engine VCR arrangement 44 is situated in-line with the engine oil pump 14 and is contained generally within a crankcase of the internal combustion engine 10. The engine VCR arrangement 44 includes a planetary gear set 46 and an actuator 48, and can also include the first and second gears 34, 42 described above.
The planetary gear set 46 is situated between the first and second gears 34, 42 and transmits rotation therebetween. The first gear 34 transmits rotational drive output to the planetary gear set 46, and the second gear 42, in turn, receives rotational drive input from the planetary gear set 46—in this way, rotation of the engine crankshaft 12 translates into rotation of the eccentric shaft 38 via the planetary gear set 46. The planetary gear set 46 can have different designs, constructions, and components in different embodiments. In the embodiment presented in the figures, and referring now to
Referring now to
The ring gear 56 receives direct and immediate rotational drive input from the planet gears 54, and engages directly with the second gear 42 and transmits direct and immediate rotational drive output to the second gear 42. For engagement with the planet gears 54, the ring gear 56 has a first set of teeth 68 located internally thereon and that extend radially inward with respect to the annular components of the planetary gear set 46. And for engagement with the second gear 42, the ring gear has a second set of teeth 70 located externally thereon and that extend radially outward with respect to the annular components of the planetary gear set 46. The second set of teeth 70 makes teeth-to-teeth meshing with the set of external teeth of the second gear 42.
Still referring to
As described,
In an operating state in which the eccentric shaft 38 is not in the midst of shifting, the engine crankshaft 12 rotates and, as a consequence, the first gear 34 rotates as well. The first gear 34 drives rotation of the sun gear 52 via their intermeshing teeth. The sun gear 52 causes the planet gears 54 to revolve in place which, in turn, rotates the ring gear 56. Due to their intermeshing teeth, the second gear 42 is driven to rotate by the ring gear 56. The eccentric shaft 38, having the second gear 42 mounted to it, is hence driven to rotate. Under this operating state, the planet gear carrier 58 does not itself rotate about the primary axis 50 and rather remains rotationally static relative to the primary axis 50. Furthermore, the actuator 48 stays deactivated in this state. Amid these rotations and between the engine crankshaft 12 and the eccentric shaft 38, a rotational speed reduction and a torque increase is furnished—this is demanded in certain VCR systems. In an example, the rotational speed reduction from the engine crankshaft 12 to the eccentric shaft 38 is approximately halved (i.e., the engine crankshaft 12 rotates at twice the speed of the eccentric shaft 38), and the torque increase from the engine crankshaft 12 to the eccentric shaft 38 is approximately doubled (i.e., the engine crankshaft 12 exerts a torque which is one-half the torque exerted by the eccentric shaft 38). This rotational speed reduction and torque increase is established by way of various relationships among the gears of the engine VCR arrangement 44. Other magnitudes of rotational speed decrease and of torque increase can be furnished by other examples and other embodiments.
In order to make changes to the compression ratio of the internal combustion engine 10, the rotational position of the eccentric shaft 38 is shifted relative to the rotational position of the engine crankshaft 12. In other words, the eccentric shaft 38 is angularly displaced (clockwise or counterclockwise) with respect to the rotational position of the engine crankshaft 12. In an illustration of shifting, the eccentric shaft 38 moves from a first rotational position thereof to a second rotational position thereof relative to the same rotational position of the engine crankshaft 12. To initiate shifting, the actuator 48 is activated and—due to its coupling to the planet gear carrier 58—alters the rotational position of the planet gear carrier 58. Unlike the previous operating state described above, amid shifting the planet gear carrier 58 rotates about the primary axis 50 and is no longer static in this regard. Rotation of the planet gear carrier 58 in this operating state drives rotation of the ring gear 56. The ring gear 56 in turn drives rotation of the second gear 42, which shifts the rotational position of the eccentric shaft 38 relative to the rotational position of the engine crankshaft 12. The eccentric shaft's position can be shifted as desired to change the compression ratio of the internal combustion engine 10.
The engine VCR arrangement 44 is designed and constructed to satisfy—or at least not substantially enlarge—packaging demands in an automotive internal combustion engine which can oftentimes be exacting and inflexible. The planetary gear set 46 is configured about the primary axis 50, along with the engine oil pump 14 and the actuator 48; these three components thus share the common centerline of the primary axis 50. Still, in other embodiments the engine oil pump 14 need not be configured about the primary axis 50. Situating the planetary gear set 46 off-axis relative to the engine crankshaft axis 18 averts an addition to the overall package length of the internal combustion engine 10 which might otherwise occur. Furthermore, although parallel, the primary axis 50, engine crankshaft axis 18, and eccentric shaft axis 40 are all non-concentric with respect to one another (this is perhaps demonstrated best by
It is to be understood that the foregoing is a description of one or more aspects of the disclosure. The disclosure is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the disclosure or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.
As used in this specification and claims, the terms “e.g.,” “for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.
