SHAFT PHASING MECHANISM FOR A VARIABLE COMPRESSION

RATIO ENGINE

CLAIM OF PRIORITY

[0001] This application claims priority to U.S. Provisional Application No. 63/035,301, filed June 5, 2020, the entire disclosure of which is incorporated by reference herein.

TECHNICAL FIELD

[0002] The presently-disclosed invention relates generally to variable compression ratio engines and, more specifically, to a shaft phasing mechanism for use therewith.

BACKGROUND

[0003] Variable compression ratio (VCR) is a technology to adjust the compression ratio of an internal combustion engine while the engine is in operation. This is done to increase fuel efficiency while under varying loads. Variable compression engines allow the volume above the piston at top dead center to be changed. Higher loads require lower ratios to increase power, while lower loads need higher ratios to increase efficiency, i.e. to lower fuel consumption. For automotive use this needs to be done as the engine is running in response to the load and driving demands.

[0004] Gasoline engines have a limit on the maximum pressure during the compression stroke, after which the fuel/air mixture detonates rather than burns. To achieve higher power outputs at the same speed, more fuel must be burned and therefore more air is needed. To achieve this, turbochargers or superchargers are used to increase the inlet pressure. This would result in detonation of the fuel/air mixture unless the compression ratio was decreased, i.e. the volume above the piston made greater. This can be done to a greater or lesser extent with massive increases in power being possible. The down side of this is that under light loading, the engine can lack power and torque. The solution is to be able to vary the inlet pressure and adjust the compression ratio to suit. This gives the best of both worlds, a small efficient engine capable of great power on demand. In addition, VCR allows free use of different fuels besides gasoline, such as, but not limited to, ethanol. Cylinder displacement is altered by using a hydraulic system connected to the crank shaft and adjusted according to the load and acceleration required.

[0005] There at least remains a need, therefore, for shaft phasing mechanisms, and processes for producing the same, that are suitable for use in variable compression ratio engines.

SUMMARY OF THE INVENTION

[0006] One embodiment of the present invention provides a shaft phasing mechanism for a variable compression ratio engine having an input shaft assembly including an input shaft with a first end and a second end, a twisted shaft portion, an input shaft gear, and an output shaft assembly including an output shaft with a first end and a second end, an output shaft gear, and a roller bearing complement, the output shaft assembly defining a central bore therethrough, wherein the input shaft assembly is rotatably received in the central bore of the output shaft assembly such that the roller bearing complement is in contact with the twisted shaft portion. [0007] Another embodiment of the present invention provides a shaft phasing mechanism having an input shaft assembly including an input shaft with a first end and a second end, a twisted shaft portion, an input shaft gear, and an output shaft assembly including an output shaft with a first end and a second end, an output shaft gear, and a roller bearing complement, the output shaft assembly defining a central bore therethrough, wherein the input shaft assembly is rotatably received in the central bore of the output shaft assembly such that the roller bearing complement is in contact with the twisted shaft portion.

[0008] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0009] The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not, all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

[0010] Figure 1 is a perspective view of an input shaft assembly of a shaft phasing mechanism constructed in accordance with an embodiment of the present invention as shown in Figure 3;

[0011] Figure 2 is a perspective view of an output shaft assembly of the shaft phasing mechanism shown in Figure 3;

[0012] Figures 3 and 4 are perspective views of a shaft phasing mechanism constructed in accordance with an embodiment of the present invention;

[0013] Figures 5 and 6 are cross-sectional views of the shaft phasing mechanism shown in Figures 3 and 4, taken along line 5-5;

[0014] Figure 7 is a cross-sectional view of the shaft phasing mechanism shown in

Figure 3, taken along line 7-7; and [0015] Figures 8 and 9 are cross-sectional views of the shaft phasing mechanism shown in Figure 3, taken along line 8-8.

[0016] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention according to the disclosure.

DETAILED DESCRIPTION

[0017] The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not, all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification, and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise.

[0018] Referring now to the figures, this disclosure is for a variable compression ratio phaser 100 for an internal combustion engine. The phaser 100 allows a phase angle to be adjusted between an input gear 114 of an input gear assembly 110 and output gear 124 of an output gear assembly 120 of the phaser 100. The input gear 114 is engaged with an eccentric shaft (not shown) and the output gear 124 is engaged with a crankshaft (not shown), with the crankshaft and the eccentric shaft being connected by way of a linkage assembly. Adjustment of the phase angle allows for adjustment of the engine’s compression ratio. As shown in the figures, the present embodiment of the shaft phasing mechanism 100 includes an input gear 114 that is non-rotatably fixed to an elongated shaft of the input shaft assembly 110. As shown in Figure 5, the elongated portion of the input shaft assembly 110 is rotatably received within a central bore of the output shaft assembly 120. As best seen in Figures 3 and 4, a first end 113 of the elongated shaft of the input shaft assembly 110 includes a bearing seat 115. The bearing seat 115 allows the input shaft assembly 110 to be rotatably mounted at a first end to a mounting surface by a clamp assembly 117.

[0019] As shown, the input shaft assembly 110 includes a twisted shaft portion 112 formed of multiple bearing surfaces 109, four in the present example, and the input shaft gear 114 disposed along its length. The multiple bearing surfaces 109 of the twisted shaft portion 112 each serve as a bearing surface for a corresponding roller 123 of the shaft roller bearing complement 122 of the output shaft assembly 120, as discussed in greater detail below. A second end 111 of input shaft assembly 110 extends outwardly beyond a first end 121 of output shaft assembly 120, as best seen in Figure 5. The first end 121 of output shaft assembly 120 is also mounted to a mounting surface by a clamp assembly 123.

[0020] Referring now to Figure 2, the output shaft assembly 120 of the variable compression ratio phaser 100 includes an output shaft roller bearing complement 122 and an output shaft (helix) gear 124. As shown, the roller bearing complement 122 of the output shaft assembly 120 preferably includes four bearing rollers 123. As best seen in Figures 5 through 7, each bearing roller 123 of the roller bearing complement 122 of the output shaft assembly 120 is axially movable with respect to the twisted shaft portion 112 of the input shaft assembly 100 by way of a linear actuator 130.

[0021] The present design uses the combination of shifting the output shaft assembly 120 output helix gear 124 with respect to the input shaft assembly 110 input gear 114 and shifting the roller bearing complement 122 of the output shaft assembly 120 along the bearing surfaces 109 of the twisted shaft 112 of the input shaft assembly 110 to accomplish phasing. During operation, as torque from the engine (not shown) is increased or decreased through the input gear 114, a linear actuator 130 is utilized to move the output shaft assembly 120 either left or right, as viewed in Figure 5, axially along the input shaft assembly 110. Dependent upon whether an increased compression ratio, in which the position of the engine’s pistons are moved upwardly within the corresponding bores, or a decreased compression ratio, in which the position of the pistons are moved downwardly within the corresponding bores, is desired, the output shaft assembly 120 is moved to the left or right along the input shaft assembly 110. A portion of the phasing takes place as a result of the output shaft gear 124 shifting axially with respect to the input shaft gear 114. Another portion of the phasing takes place as a result of the output shaft roller bearing complement 122 following the bearing shaft surfaces 109 of the twisted shaft portion 112 of the input shaft assembly 110. As shown, the input gear 114 and the twisted shaft 112 have helix twists in opposite directions. Note, rather than a linear actuator 130, a hydraulic cylinder may be used to shift the output shaft assembly 120 of the phaser 100 with respect to the input shaft assembly 110.

[0022] These and other modifications and variations to the invention may be practiced by those of ordinary skill in the art without departing from the spirit and scope of the invention, which is more particularly set forth in the appended claims. For example, two bearings may be used to support the output shaft 120 and provide preload. Those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and it is not intended to limit the invention as further described in such appended claims. Therefore, the spirit and scope of the appended claims should not be limited to the exemplary description of the versions contained herein.