Stellantis Granted Patent for Three-Speed Gearbox For EVs
New Gearbox Design Can Be Used For EVs and Hybrids...
Stellantis (FCA US, LLC) continues to push the boundaries of electric vehicle (EV) technology. Following the February 2024 grant of a patent for a two-speed gearbox designed for electric off-road SUVs, the company has now secured another patent—this time for a three-speed gearbox for electric and hybrid vehicles. The new gearbox design, initially filed in August 2023, was officially granted on September 17th, 2024.
Addressing Gearbox Challenges in EVs –
Most EVs today are equipped with single-speed gearboxes. While these systems excel in torque delivery, they can struggle to sustain high torque over long periods or provide a range of speeds, limiting performance, especially on highways. Stellantis’ new three-speed gearbox aims to overcome these challenges by delivering better torque control and a more flexible speed range.
Gearbox Assembly Details –
The patent describes a three-speed gearbox assembly for EVs featuring several advanced components:
- First Planetary Gear Set: This is directly connected to the electric motor output. A first clutch can couple the motor to a second portion of the gear set, while a second clutch can ground this portion to the housing.
- Second Planetary Gear Set: Connected to the output of the first gear set and linked to the vehicle’s first axle shaft, it transmits power through a carrier, further improving the system’s flexibility.
- Third Planetary Gear Set: This set connects the output of the second gear set to the vehicle’s second axle shaft. A third clutch grounds this gear set to the housing as necessary, while the fourth clutch provides a locked differential function by connecting the two axle shafts for additional traction control.
The system’s clutches operate in various combinations to enable different gears:
- First Gear: This gear engages the second and third clutches, providing maximum torque for low-speed operations such as off-road driving.
- Second Gear: Engages the first and third clutches for balanced power and efficiency in on-road driving.
- Third Gear: Engages the second and fourth clutches for high-speed efficiency.
Additionally, the fourth clutch allows for locking the first and second axle shafts, which is essential for scenarios requiring enhanced traction, such as off-road driving.
Detailed Gear System Breakdown –
The planetary gear sets in the assembly consist of a central “sun” gear, planet gears, and a ring gear. These components work together to manage power transmission efficiently:
- First Planetary Gear Set: This set comprises a sun gear that can be selectively coupled to the electric motor or grounded via clutches, with a ring gear transferring power to the second planetary gear set.
- Second Planetary Gear Set: The sun gear connects to the first set’s output, with its carrier linked to the first axle, distributing power to the wheels.
- Third Planetary Gear Set: This set features a sun gear connected to the output of the second set and a carrier that can be grounded via a clutch. The ring gear is linked to the second axle shaft, completing the power flow to both wheels.
The assembly also includes limited-slip clutches on both axle shafts, which ensure improved traction and handling in diverse driving conditions.
Advantages of the Three-Speed Gearbox –
This advanced gearbox offers several advantages over traditional single-speed EV gearboxes:
- Improved Torque Control: The multi-speed design allows for better torque management at low speeds while maintaining efficiency at higher speeds.
- Enhanced Performance: The gearbox’s locked differential function and flexible gear operation support both off-road and highway driving.
- Scalability: This design can be adapted to a wide range of electric and hybrid vehicles, providing Stellantis with flexibility in its future EV lineup.
Looking Ahead –
As the electrified market expands, innovations like Stellantis’ three-speed gearbox will be instrumental in advancing vehicle performance. This patent aims to address the limitations of current EV technology, positioning Stellantis as a leader in developing more versatile and capable electric drivetrains. The automaker can enhance efficiency and power across its evolving lineup by integrating this technology into its future electric and hybrid models.
Source: USPTO
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