CONTINUOUSLY VARIABLE TRANSMISSION

• US 20170159812A1
• Filed: 02/17/2017
• Published: 06/08/2017
• Est. Priority Date: 10/14/2008
• Status: Active Grant

• Current Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Original Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Inventors: Pohl, Brad P., McBroom, Scott T., Thomassy, Fernand A., Lohr, Charles B.
• Granted Patent: US 10,253,880 B2
• Time in Patent Office: Days
• CPC Class Codes: F02B 67/04 of mechanically-driven auxiliary apparatus
• CPC Class Codes: F16H 15/40 in which two members co-operative by means of balls, or rollers of uniform effective diameter, not mounted on shafts
• CPC Class Codes: F16H 15/42 in which two members co-operate by means of rings or by means of parts of endless flexible members pressed between the first mentioned members
• CPC Class Codes: F16H 15/50 Gearings providing a continuous range of gear ratios
• CPC Class Codes: F16H 15/503 in which two members co-operate by means of balls or rollers of uniform effective diameter, not mounted on shafts
• CPC Class Codes: F16H 15/52 in which a member of uniform effective diameter mounted on a shaft may co-operate with different parts of another member
• CPC Class Codes: F16H 2059/704 Monitoring gear ratio in CVT's
• CPC Class Codes: F16H 2061/6641 Control for modifying the ratio control characteristic
• CPC Class Codes: F16H 59/40 Output shaft speed
• CPC Class Codes: F16H 61/0021 Generation or control of line pressure
• CPC Class Codes: F16H 61/0204 for gearshift control, e.g. control functions for performing shifting or generation of shift signal
• CPC Class Codes: F16H 61/664 Friction gearings
• CPC Class Codes: F16H 61/6646 controlling shifting exclusively as a function of speed
• CPC Class Codes: F16H 63/065 hydraulic actuating means
• CPC Class Codes: F16H 63/067 mechanical actuating means
• CPC Class Codes: F16H 63/42 Ratio indicator devices
• CPC Class Codes: Y02T 10/60 Other road transportation technologies with climate change mitigation effect
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

Inventive embodiments are directed to components, subassemblies, systems, and/or methods for continuously variable accessory drives (CVAD). In one embodiment, a skew-based control system is adapted to facilitate a change in the ratio of a CVAD. In another embodiment, a skew-based control system includes a skew actuator coupled to a carrier member. In some embodiments, the skew actuator is configured to rotate a carrier member of a CVT. Various inventive traction planet assemblies can be used to facilitate shifting the ratio of a CVT. In some embodiments, the traction planet assemblies include legs configured to cooperate with the carrier members. In some embodiments, a traction planet assembly is operably coupled to the carrier members. Embodiments of a shift cam and traction sun are adapted to cooperate with other components of the CVT to support operation and/or functionality of the CVT. Among other things, shift control interfaces for a CVT are disclosed.

Claims

1. A method for controlling a continuously variable accessory drive (CVAD) with a continuously variable transmission (CVT) coupled to a prime mover and a load, the CVT having a plurality of traction planets, each traction planet adapted to rotate about a tiltable axis, the method comprising:

a) receiving a desired output speed for the CVT;

b) determining a command signal for a skew actuator, the skew actuator comprising a hydraulic piston coupled to the CVAD, the hydraulic piston operably coupled to a first carrier member of the CVAD, the first carrier member comprising a plurality of radially offset slots formed in the first carrier member and arranged angularly about a longitudinal axis of the CVAD;

c) applying the command signal to the skew actuator, wherein applying the command signal to the skew actuator causes the first carrier member to rotate about the longitudinal axis to apply a skew condition to tilt the axes of the plurality of traction planets, wherein the tilt angle determines an output speed of the CVT;

d) measuring the output speed of the CVT;

e) comparing the measured output speed to the desired output speed; and

f) repeating step b) through step e) until the measured output speed is substantially equal to the desired output speed.

2. The method of claim 1, wherein applying the command signal to the skew actuator applies a relative motion between the first carrier member and a second carrier member of the CVAD.

3. The method of claim 1, wherein a feedback signal is configured to represent an actual output speed.

4. The method of claim 1, wherein a feedback signal is an indication of an actual output speed.

5. A continuously variable transmission (CVT) system for use in a continuously variable accessory drive (CVAD), comprising:

an input driver for receiving power from an input shaft coupled to an external source;

a first traction ring coupled to the input driver for receiving power;

a variator assembly coupled to the first traction ring for receiving power from the first traction ring;

a second traction ring coupled to the variator assembly for receiving power from the variator assembly;

a planetary gear assembly coupled to the second traction ring and further coupled to an output shaft; and

a controller operable to;

a) receive a desired output speed for the CVT;

b) determine a command signal for a skew actuator, the skew actuator comprising a hydraulic piston coupled to the CVAD, the hydraulic piston operably coupled to a first carrier member of the CVAD, the first carrier member comprising a plurality of radially offset slots formed in the first carrier member and arranged angularly about a longitudinal axis of the CVAD;

c) apply the command signal to the skew actuator, wherein applying the command signal to the skew actuator causes the first carrier member to rotate about the longitudinal axis to apply a skew condition to tilt the axes of the plurality of traction planet assemblies, wherein the tilt angle determines an output speed of the CVT;

d) measure the output speed of the CVT;

e) compare the measured output speed to the desired output speed; and

f) repeat step b) through step e) until the measured output speed is substantially equal to the desired output speed.

6. The CVT system of claim 5, wherein the output shaft is coupled to a ring gear of the planetary gear assembly.

7. The CVT system of claim 5, wherein a planetary sun driver is coupled to a sun gear of the planetary gear assembly.

8. The CVT system of claim 7, wherein an axial force generator is coupled to the second traction ring and further coupled to the planetary sun driver.

9. The CVT system of claim 5, wherein the skew actuator comprises a servo motor.

10. The CVT system of claim 5, wherein the skew actuator comprises an electro-hydraulic actuator.