1. Method for establishing a preferred operating point for a preselected powertrain operating parameter in a powertrain system, comprising:
determining a feasible operating space for the preselected powertrain operating parameter;
searching the feasible operating space for a value corresponding to a substantially minimum system power loss; and,
establishing the preferred operating point as the value corresponding to the substantially minimum system power loss.
2. The method for establishing a preferred operating point for a preselected powertrain operating parameter as claimed in claim 1 wherein said preselected powertrain parameter comprises an input torque.
3. The method for establishing a preferred operating point for a preselected powertrain operating parameter as claimed in claim 1 wherein said powertrain system includes an internal combustion engine, a transmission, an electric machine and an energy storage device.
4. The method for establishing a preferred operating point for a preselected powertrain operating parameter as claimed in claim 3 wherein said substantially minimum system power loss is further determined by factoring in a subjective power loss not related to an actual sub-system power loss but effective to a bias said substantially minimum power loss toward values of the preselected powertrain operating parameter which require less energy storage device use.
5. The method for establishing a preferred operating point for a preselected powertrain operating parameter as claimed in claim 3 wherein said substantially minimum system power loss is further determined by factoring in a subjective power loss not related to an actual sub-system power loss but effective to a bias said substantially minimum power loss toward values of the preselected powertrain operating parameter which require more energy storage device use.
6. The method for establishing a preferred operating point for a preselected powertrain operating parameter as claimed in claim 1 wherein said preferred operating point is periodically updated, and further wherein such periodic update proceeds during quiescent powertrain operation only when the value for the most recent search corresponds to a respective minimum power loss that is at least a predetermined amount less than the respective minimum power loss corresponding to the previously established preferred operating point.
7. The method for establishing a preferred operating point for a preselected powertrain operating parameter as claimed in claim 1 wherein said substantially minimum system power loss is determined from a plurality of sub-system power losses.
8. The method for establishing a preferred operating point for a preselected powertrain operating parameter as claimed in claim 1 wherein searching the feasible operating space for a value comprises performing a section search.
9. The method for establishing a preferred operating point for a preselected powertrain operating parameter as claimed in claim 8 wherein said section search comprises a golden section ratio.
10. Method for determining a preferred input torque for efficiently operating an electrically variable transmission including an input, an output and an electric machine having known coupling relationships, and an energy storage system, comprising:
determining current EVT operating conditions including input, output and electric machine speeds;
determining system constraints in electric machine torque, battery power and input torque at current EVT operating conditions;
providing a target output torque producible within said system constraints;
calculating aggregate power losses corresponding to feasible input torques that can produce the target output torque within said system constraints;
converging upon a feasible input torque corresponding to a substantially minimum aggregate power loss; and,
selecting as the preferred input torque the feasible input torque corresponding to the substantially minimum aggregate power loss.
11. The method for determining a preferred input torque as claimed in claim 10 wherein calculating aggregate power losses comprises:
calculating individual sub-system power losses; and,
summing the individual sub-system power losses.
12. The method for determining a preferred input torque as claimed in claim 11 wherein individual sub-system power losses are selected from the group consisting of an input source power loss, an electric machine power loss, an energy storage system power loss, and an accessory power loss.
13. The method for determining a preferred input torque as claimed in claim 10 wherein calculating aggregate power losses includes biasing power losses higher as a predetermined function of energy storage system use.
14. The method for determining a preferred input torque as claimed in claim 10 wherein said preferred input torque is periodically updated, and further wherein such periodic update proceeds during quiescent powertrain operation only when the most recently selected feasible input torque corresponds to a respective substantially minimum aggregate power loss that is at least a predetermined amount less than the respective substantially minimum aggregate power loss corresponding to the previously selected feasible input torque.
15. The method for determining a preferred input torque as claimed in claim 10 wherein converging upon a feasible input torque comprises performing a section search in feasible input torques and corresponding aggregate power losses.
16. The method for determining a preferred input torque as claimed in claim 15 wherein said section search comprises a golden section ratio.
17. The method for determining a preferred input torque as claimed in claim 10 wherein converging upon a feasible input torque comprises performing an iterative derivative convergence.
18. The method for determining a preferred input torque as claimed in claim 10 wherein converging upon a feasible input torque comprises performing polynomial estimations.
19. A hybrid powertrain system comprising:
an engine;
an electric machine;
an energy storage system;
an output;
wherein the energy storage system and electric machine are electrically-operatively coupled for power flow therebetween, and wherein the engine, electric machine and output are mechanically-operatively coupled for power flow therebetween; and
a computer based controller including a storage medium having a computer program encoded therein for determining an engine torque at predetermined engine speed and output speed conditions that result in a substantially minimum powertrain power loss, said computer program including
code for determining a feasible operating space for engine torque; and,
code for searching the feasible operating space for a value of engine torque corresponding to a substantially minimum powertrain system power loss.
20. The hybrid powertrain as claimed in claim 19 wherein the code for determining a feasible operating space for engine torque comprises:
code for determining current powertrain system operating conditions including engine, output and electric machine speeds; and,
code for determining powertrain system constraints in electric machine torque, energy storage system power and engine torque at current powertrain system operating conditions.
21. The hybrid powertrain as claimed in claim 20 wherein the code for searching the feasible operating space for a value of engine torque corresponding to a substantially minimum powertrain system power loss comprises:
code for providing a target output torque producible within said powertrain system constraints;
code for calculating aggregate powertrain system power losses corresponding to engine torques that can produce the target output torque within said powertrain system constraints;
code for converging upon an engine torque corresponding to a substantially minimum calculated aggregate powertrain system power loss; and,
code for selecting as the value of engine torque corresponding to a substantially minimum powertrain system power loss the engine torque corresponding to the substantially minimum calculated aggregate powertrain system power loss.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A posterior-stabilized femoral component adapted to articulate with a tibial bearing component in a knee prosthesis, the tibial bearing component including a proximally extending spine, the femoral component comprising:
medial and lateral condyles shaped to articulate with the tibial bearing component through a range of motion, in which full extension corresponds to zero degrees flexion of the knee prosthesis and positive flexion corresponds to greater than zero degrees flexion of the knee prosthesis,
said medial and lateral condyles comprising inwardly facing condylar walls forming an intercondylar space therebetween, said intercondylar space having a mediallateral width; and
a femoral cam sized and positioned to engage the spine of the tibial bearing component in positive flexion through a portion of the range of motion, said femoral cam comprising a mediallateral cam length spanning said intercondylar space such that said femoral cam joins said medial and lateral condyles to one another,
said femoral cam having an articular surface comprising:
a central articular surface that is one of cylindrical and convex across a mediallateral extent of said central articular surface;
a convex medial transition surface flanking said central articular surface and disposed between said central articular surface and said medial condyle; and
a convex lateral transition surface flanking said central articular surface and disposed between said central articular surface and said lateral condyle,
said convex medial transition surface and said convex lateral transition surface each defining an arc extending in a mediallateral direction, said arc defining a radius equal to between 40% and 60% of said mediallateral cam length, whereby said femoral cam defines widely rounded, convex surfaces.
2. The posterior-stabilized femoral component of claim 1, wherein said central articular surface comprises up to 25% of said mediallateral cam length.
3. The posterior-stabilized femoral component of claim 1, wherein said convex medial transition surface and said convex lateral transition surface cooperate to comprise at least 60% of said mediallateral cam length.
4. The posterior-stabilized femoral component of claim 1, wherein said central articular surface comprises a cylindrical surface having an axial extent along the mediallateral direction.
5. The posterior-stabilized femoral component of claim 1, wherein said femoral cam defines a plurality of convex surfaces, said plurality of convex surfaces each defining a radius of at least 2.5 mm.
6. The posterior-stabilized femoral component of claim 1, wherein said articular surface of said femoral cam defines a minimum radius of 1 mm across the entirety of said mediallateral cam length.