Patent Application
20170167606
This disclosure relates generally to continuously variable transmissions (CVTs), and more particularly to off-road vehicle CVTs.
CVTs are generally known. The CVT has features including linking two shafts with a variable gear ratio, permitting a gradient, rather than a set of fixed gear ratios. However, in simplified systems as often seen on off-road vehicles, CVTs often need to be adjusted for different uses and desired behaviors, which often requires a partial disassembly of the drivetrain, and a stop in driving.
It would be useful to improve this shifting mechanism to facilitate a more versatile tuning adjustment system that does not require drivetrain disassembly, or even a stop of the engine.
One embodiment described herein is an apparatus that comprises a continuously variable transmission, in which an actual speed ratio is feedback-controlled to a target speed ratio, in addition to a communications system configured to enable wireless communication with an external computer, and a control system configured to allow the target speed ratio to be controlled via the aforementioned external device.
Another embodiment described herein is control method that includes gathering rotational speed data of a primary pulley in a vehicle transmission, retrieving target speed data from an external computer through a wireless connection, and feedback-controlling the primary pulley in the vehicle transmission based upon the ratio between target and measured rotational speeds.
The primary pulley of the CVT has an internal measurement system for measuring rotational speeds, a CVI control unit for interpreting these speeds and controlling the unit accordingly, and an extern& communication system for communicating with an external system in order to change the CVT Control. External to the system exists a computer system that relays information to the main CVI unit remotely.
Definitions:
As used herein, the term “communications system” means computer hardware and computer software that transmits data between the CVT control system and an external computer system in any wireless method, including but not limited to: Bluetooth, Wi-Fi, and radio transmission.
As used herein, the term “control system” means computer hardware and software that adjusts the speed ratio of the transmission in response to data received from the internal measurement system as well as data received from the external communication system.
As used herein, the term “computer” means any hardware and software capable of accepting, processing, and outputting data.
As used herein, the term “internal measurement system” means any hardware and software for measuring or recording rotational speed information.
The system includes a plurality of pulleys. The primary and secondary pulleys have grooves that are aligned so that a belt can pass between. The primary pulley is mounted coaxially with an engine, while the secondary pulley is mounted coaxially to a shaft of the final drive system.
The rotation of the primary pulley is transmitted to the secondary pulley via the belt, and the rotation of the secondary pulley is transmitted to a final drive system, comprising an output shaft, a gear set and a differential gear device.
To make a speed ratio between the primary pulley and the secondary pulley changeable during the above power transmission, one of the conical plates forming the groove of each of the primary pulley and the secondary pulley is a fixed conical plate, while the other conical plate is movable in an axial direction. This effectively controls both pulley diameters, thereby changing the ratio of their speeds.
By linking the CVT to an external communication system, it is therefore effectively possible to control the target speed of the primary CVT externally without stopping the CVT from spinning. In one embodiment, the computer system is linked to a GPS system that allows the drive unit to “shift” based upon vehicle location or speed, without necessitating a complete overhaul of an existing system.
The apparatus and method described herein is particularly useful for terrain vehicles, including but not limited to all-terrain vehicles and SAE Baja competition vehicles. Many automobiles facilitate the in-operation shifting of target speeds using onboard computers. The proposed invention avoids the complexities of mounting and programming these systems to interface with existing vehicular systems, and potentially allows for the simple swap of CVT pulleys in order to achieve similar aims. This would avow for increased transmission performance on a variety of vehicular platforms.
